A rotation detection circuit detects an induced current flowing through a drive coil of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not the induced current exceeds a predetermined reference value in each of the sections. A control unit selects a drive pulse corresponding to the rotation state detected by the rotation detection unit, and supplies a drive current to a drive coil to rotatably drive the stepping motor. The rotation detection unit carries out detection by selecting a detection direction of the induced current in the sections after the first section on the basis of whether or not the induced current exceeding each of a plurality of reference values is detected plural times in the first section.

Description

31 parts

›BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stepping motor control circuit, a movement provided with the stepping motor control circuit, and an analog electronic timepiece using the movement.

2. Background Art

In the related art, a stepping motor, which is provided with a stator having a rotor accommodation through-hole and a plurality of positioning units that determine a stable stationary position of a rotor, the rotor being disposed inside the rotor accommodation through-hole, and a drive coil being wound around the stator, has been used in an analog electronic timepiece and the like. To allow the stepping motor to rotate in a relatively reliable manner, rotation detection thereof is carried out to allow the stepping motor to operate according to rotation detection results (for example, refer to Japanese Patent Nos. 3302804 and 4165092, International Publication No. 2005/119377, and JP-A-2010-166798).

A rotation detection method described in Japanese Patent Nos. 3302804 and 4165092 is configured to have a first detection section in which a rotor movement state after blocking a drive pulse is detected, and a second detection section in which an induced signal in a direction opposite to that of the first detection section is detected to carry out the final rotation determination based on the result. According to this configuration, rotation detection of the stepping motor is carried out, and the stepping motor is allowed to rotatably drive by the drive pulse according to rotation detection results.

The rotation detection is possible by the configuration. However, there is a problem in that in a case where a load variation (a calendar load, or a load of a moment of the long hand) is large, an induced signal varies, and thus accurate rotation detection is difficult.

On the other hand, a rotation detection method described in International Publication No. 2005/119377 is configured as follows. After rotating a rotor with a main drive pulse P 11 , when a detection voltage of an induced signal is less than a reference voltage Vcomp, the rotor is driven with a correction drive pulse P 2 , and the rotor is driven after changing (pulse-up) a next main drive pulse P 1 to a main drive pulse P 12 having energy larger than that of the main drive pulse P 11 . In addition, when it is detected that a detection time during rotation with the main drive pulse P 12 is faster than a reference time, the main drive pulse P 12 is pulsed down to the main drive pulse P 11 to allow the rotor to drive with an appropriate main drive pulse P 1 .

However, the detection method is a rotation detection method using a phenomenon in which a detection time of the induced signal is delayed along with a relative load increase with respect to the drive energy, and a level of the induced signal decreases. Accordingly, when a load variation (a calendar load, or a load of a moment of the long hand) which is equal to or more than a certain load variation occurs, an angular velocity of the rotor decreases, and thus the induced signal is apt to decrease regardless of rotation. Therefore, there is a problem in that rotation is falsely detected as non-rotation, and thus the rotor is driven with the correction drive pulse. As a result, there is a problem in that a consumption current increases, and the lifetime of a battery decreases.

In addition, the rotation detection method described in JP-A-2010-166798 is a rotation detection method using a phenomenon in which the detection time of the induced signal is delayed along with an increase in a load, and a pattern of an induced signal VRs in sections obtained by dividing a detection section into a plurality of sections is different depending on a rotation state of the stepping motor. However, similarly to the invention described in International Publication No. 2005/119377, there is a problem in that false rotation detection may be conducted due to an effect of a load variation, and power consumption may increase.

›SUMMARY OF THE INVENTION

It is an aspect of the present application to conduct accurate rotation detection by reducing an effect due to a load variation.

According to the application, there is provided a stepping motor control circuit including: a rotation detection unit that detects an induced current flowing through a drive coil due to free vibration of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not an induced current exceeding a predetermined reference value is detected in each of the sections by using a phenomenon in which a detection time of the induced current is delayed along with a relative load increase with respect to drive energy, and a level of the induced current decreases; and a control unit that selects a drive pulse corresponding to the rotation state that is detected by the rotation detection unit among a plurality of kinds of drive pulses, each having different energy, and supplies a drive current to the drive coil by the selected drive pulse to rotatably drive the stepping motor. The rotation detection unit carries out the detection by selecting a detection direction of the induced current in sections after a first section on the basis of whether or not the induced current exceeding a predetermined reference value is detected in the first section that is an initial section of the detection section, and detects the rotation state of the stepping motor by a pattern based on the induced current detected in each of the sections.

According to the application, there is provided a stepping motor control circuit including: a rotation detection unit that detects an induced current flowing through a drive coil due to free vibration of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not an induced current exceeding a predetermined reference value is detected in each of the sections by using a phenomenon in which a detection time of the induced current is delayed along with a relative load increase with respect to drive energy, and a level of the induced current decreases; and a control unit that selects a drive pulse corresponding to the rotation state that is detected by the rotation detection unit among a plurality of kinds of drive pulses, each having different energy, and supplies a drive current to the drive coil by the selected drive pulse to rotatably drive the stepping motor. The rotation detection unit includes first and second detection elements that detect induced currents flowing through the drive coil due to free vibration of the stepping motor in directions opposite to each other, and is configured to detect the induced current in the detection section by alternately repeating a first closed circuit including the drive coil of the stepping motor and the detection elements, and a second closed circuit constituted by the drive coil and a low-impedance element. In a first section that is an initial section of the detection section, the rotation detection unit carries out the detection by selecting a detection element to be used in sections after the first section on the basis of detection results of the induced current using the first and second detection elements, and detects the rotation state of the stepping motor by a pattern based on the induced current detected in each of the sections.

In addition, according to the application, there is provided a movement including the stepping motor control circuit.

In addition, according to the application, there is provided an analog electronic timepiece including the movement.

According to the stepping motor control circuit according to the application, accurate rotation detection may be carried out by reducing an effect of a load variation.

According to the movement according to the application, an analog electronic timepiece, which is capable of carrying out accurate rotation detection by reducing the effect of the load variation, may be constituted.

According to the analog electronic timepiece according to the application, accurate rotation detection may be carried out by reducing the effect of the load variation, and thus accurate hand movement or low power consumption may be realized.

›BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that is common to a stepping motor control circuit, a movement, and an analog electronic timepiece according to each embodiment of the invention;

FIG. 2 is a configuration diagram of the stepping motor that is used in the analog electronic timepiece according to each embodiment of the invention;

FIG. 3 is a timing diagram of the stepping motor control circuit, the movement, and the analog electronic timepiece according to a first embodiment of the invention;

FIG. 4 is a determination chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first embodiment of the invention;

FIG. 5 is a partially detailed circuit diagram of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first and third embodiments of the invention;

FIG. 6 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first embodiment of the invention;

FIG. 7 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first embodiment of the invention;

FIG. 8 is a flowchart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first embodiment of the invention;

FIG. 9 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to a second embodiment of the invention;

FIG. 10 is a determination chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention;

FIG. 11 is a partially detailed circuit diagram of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention;

FIG. 12 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention;

FIG. 13 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention;

FIG. 14 is a flowchart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention;

FIG. 15 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to a third embodiment of the invention;

FIG. 16 is a determination chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the third embodiment of the invention;

FIG. 17 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the third embodiment of the invention;

FIG. 18 is a timing chart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the third embodiment of the invention; and

FIG. 19 is a flowchart of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the third embodiment of the invention.

›DETAILED DESCRIPTION OF THE INVENTION · 1 of 28

Hereinafter, embodiments of the invention will be described. In addition, in the drawings of respective embodiments, the same reference numerals will be given to parts having the same functions.

FIG. 1 shows a block diagram common to a stepping motor control circuit according to each embodiment of the invention, a movement provided with the stepping motor control circuit, and an analog electronic timepiece provided with the movement. FIG. 1 illustrates an example of an analog electronic watch.

In FIG. 1 , the analog electronic timepiece includes an oscillation circuit 101 that generates a signal of a predetermined frequency, a frequency dividing circuit 102 that frequency-divides the signal generated in the oscillation circuit 101 to generate a timepiece signal serving as a reference of time counting, and a control circuit 103 that carries out various kinds of control such as control of respective electronic circuit elements constituting an electronic timepiece, and change control of a drive pulse (pulse control) starting from a time counting operation by counting the timepiece signal.

In addition, the analog electronic timepiece includes a main drive pulse generation circuit 104 that selects any of a plurality of kinds of main drive pulses P 1 , each having different energy, on the basis of a main drive pulse control signal transmitted from the control circuit 103 , and that outputs the selected main drive pulse P 1 , and a correction drive pulse generation circuit 105 that outputs a correction drive pulse P 2 having energy larger than that of the respective main drive pulses P 1 on the basis of a correction drive pulse control signal transmitted from the control circuit 103 .

In addition, the analog electronic timepiece includes a motor driver circuit 106 that drives a stepping motor 107 on the basis of the main drive pulse P 1 transmitted from the main drive pulse generation circuit 104 , and the correction drive pulse P 2 transmitted from the correction drive pulse generation circuit 105 , and the stepping motor 107 .

In addition, the analog electronic timepiece includes a timepiece case 111 , an analog display portion 112 that is disposed on an outer surface side of the timepiece case 111 , and has time indicating hands (an hour hand 114 , a minute hand 115 , and a second hand 116 ) that are driven by the stepping motor 107 or a calendar display portion (not shown), and a movement 113 that is disposed inside the timepiece case 111 .

In addition, the analog electronic timepiece includes a rotation detection circuit 108 that detects an induced current Ik that is generated due to free vibration of the stepping motor 107 and exceeds each of a plurality of predetermined reference values (two kinds including a first reference value and a second reference value) in a detection section T immediately after driving the stepping motor 107 by the main drive pulses P 1 , and a detection section determination circuit 109 that determines whether or not the rotation detection circuit 108 detects the induced current Ik exceeding the reference values in which section within the detection section T.

In addition, the details will be described later, but the rotation detection circuit 108 is configured to detect the induced current Ik exceeding the reference values by converting the induced current Ik to a voltage by a detection element. A case in which an induced voltage signal VRs exceeding a predetermined first reference voltage Vinv is detected is equivalent to a case in which the induced current Ik exceeding the first reference value is detected. In addition, a case in which an induced voltage signal VRs exceeding a predetermined second reference voltage Vcomp is detected is equivalent to a case in which an induced current Ik exceeding the second reference value is detected. The second reference value is larger than the first reference value, and the second reference voltage Vcomp is set to a value larger than that of the first reference voltage Vinv. The first reference voltage Vinv is a reference of determining a degree of margin of drive energy, and is a reference voltage at the time of carrying out rotation detection at the other polarity. The second reference voltage Vcomp is a reference voltage at the time of carrying out rotation detection at one polarity. As the first reference voltage Vinv and the second reference voltage Vcomp, a voltage having the same one polarity is used.

In addition, the detection section determination circuit 109 is configured to determine in which section within the detection section T the induced current Ik exceeding the first reference value or the second reference value is detected by determining in which section within the detection section T the induced voltage signal VRs exceeding the first reference voltage Vinv or the second reference voltage Vcomp is detected by the rotation detection circuit 108 .

The detection section T for detecting a rotation state of the stepping motor 107 is provided immediately after blocking the main drive pulses P 1 , and is divided into a plurality of sections (in this embodiment, three sections of sections T 1 to T 3 ).

The detection section determination circuit 109 determines whether or not the induced voltage signal VRs detected by the rotation detection circuit 108 exceeds the reference voltage Vinv or Vcomp in each section of the detection section T (a determination value), and outputs a detection signal indicating rotation states such as the degree of margin of drive energy and non-rotation by a combination pattern of the determination value in the respective sections (a pattern of the induced voltage signal VRs) to the control circuit 103 .

The oscillation circuit 101 , the frequency dividing circuit 102 , the control circuit 103 , the main drive pulse generation circuit 104 , the correction drive pulse generation circuit 105 , the motor driver circuit 106 , the stepping motor 107 , the rotation detection circuit 108 , and the detection section determination circuit 109 are constituent elements of the movement 113 .

›DETAILED DESCRIPTION OF THE INVENTION · 2 of 28

In general, a mechanical body of a timepiece, which is constituted by a power source of a timepiece, and devices of time reference and the like, is referred to as a movement. An electronic type mechanical body is sometimes referred to as a module. In a completed state as a timepiece, a dial plate and hands are mounted on the movement, and the movement is accommodated in the timepiece case.

The control circuit 103 also has a function of determining the rotation state of the stepping motor 107 (whether or not the stepping motor 107 rotates, the degree of margin of energy of the main drive pulse P 1 , and the like) by a pattern of determination value indicating whether or not the induced voltage signal VRs exceeds the reference voltage Vinv or Vcomp in each of the sections within the detection section T, and the like.

The rotation detection circuit 108 determines a level of the induced voltage signal VRs that is generated due to free vibration immediately after rotation driving of the stepping motor 107 , and detects a point of time at which the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is generated. The reference voltages Vinv and Vcomp are set to values with which determination of the rotation states such as rotation and non-rotation, and change control of the drive pulse (pulse control) may be carried out by a combination pattern of sections in which the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected.

In a case where the rotor of the stepping motor 107 moves at a speed exceeding a constant speed like a case in which the stepping motor 107 rotates, the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the second reference voltage Vcomp. In a case where the rotor of the stepping motor 107 does not move at a speed exceeding a constant speed like a case in which the stepping motor 107 does not rotate, the rotation detection circuit 108 does not detect the induced voltage signal VRs exceeding the second reference voltage Vcomp. The first reference voltage Vinv is set to a value lower than the second reference voltage Vcomp. For example, the second reference voltage Vcomp is set as a power supply voltage. In addition, the rotation detection circuit 108 may be configured in such a manner that the first reference voltage is set to be ½ times the power supply voltage by using a threshold voltage of an inverter as the first reference voltage Vinv when the stepping motor control circuit is made into an integrated circuit (IC).

Here, the oscillation circuit 101 and the frequency dividing circuit 102 constitute a signal generation unit, and the analog display portion 112 constitutes a display portion. The control circuit 103 , the rotation detection circuit 108 , and the detection section determination circuit 109 constitute a rotation detection unit. The main drive pulse generation circuit 104 , and the correction drive pulse generation circuit 105 constitute a drive pulse generation unit. The motor driver circuit 106 constitutes a motor drive unit. The oscillation circuit 101 , the frequency dividing circuit 102 , the control circuit 103 , the main drive pulse generation circuit 104 , the correction drive pulse generation circuit 105 , and the motor driver circuit 106 constitute a control unit. In addition, the oscillation circuit 101 , the frequency dividing circuit 102 , the control circuit 103 , the main drive pulse generation circuit 104 , the correction drive pulse generation circuit 105 , the motor driver circuit 106 , the rotation detection circuit 108 , and the detection section determination circuit 109 constitute a stepping motor control circuit.

The rotation detection unit detects the induced current Ik flowing through the drive coil 209 due to free vibration of the stepping motor 107 in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor 107 on the basis of a pattern indicating whether or not an induced current exceeding a predetermined reference value is detected in each of the sections by using a phenomenon in which a detection time of the induced current Ik is delayed along with a relative load increase with respect to drive energy of the stepping motor 107 , and a level of the induced current Ik decreases.

A hand movement operation of the respective hands (the hour hand 114 , the minute hand 115 , and the second hand 116 ) in a common operation will be schematically described below. In FIG. 1 , the oscillation circuit 101 generates a signal of a predetermined frequency, and the frequency dividing circuit 102 frequency-divides the signal generated in the oscillation circuit 101 to generate a timepiece signal (for example, a signal with a cycle of one second) serving as a reference of time counting, and outputs the resultant timepiece signal to the control circuit 103 .

The control circuit 103 counts the timepiece signal, and outputs a main drive pulse control signal to the main drive pulse generation circuit 104 in order for the stepping motor 107 to be rotatably driven with the main drive pulse P 1 having energy corresponding to the magnitude of the power supply voltage with respect to a load (that is, the degree of margin of the drive energy) at a predetermined cycle.

In each embodiment of the invention, as a drive pulse for rotatably driving the stepping motor 107 , a plurality of kinds of drive pulses are prepared. As the drive pulse, a plurality of kinds (that is, a plurality of ranks) of main drive pulses P 1 , each having different energy, and correction drive pulses P 2 having energy larger than that of the main drive pulses P 1 are used.

Each of the main drive pulses P 1 is a drive pulse that moves the time indicating hands 114 to 116 by normally rotating the stepping motor 107 during a common operation. In addition, each of the correction drive pulses P 2 is a drive pulse that forcibly rotates the stepping motor 107 in a case where the stepping motor 107 may not be rotated (normal rotation) through driving with the main drive pulse P 1 during a common operation.

›DETAILED DESCRIPTION OF THE INVENTION · 3 of 28

The main drive pulse generation circuit 104 outputs a main drive pulse P 1 with an energy rank corresponding to a main drive pulse control signal transmitted from the control circuit 103 to the motor driver circuit 106 . The motor driver circuit 106 rotatably drives the stepping motor 107 by the main drive pulse P 1 . The stepping motor 107 is rotatably driven by the main drive pulse P 1 , and rotatably drives the time indicating hands 114 to 116 . According to this, when the stepping motor 107 is normally rotated, current time display by the time indicating hands 114 to 116 is carried out in the analog display portion 112 .

The operation of the rotation detection circuit 108 is different depending on respective embodiments, and thus the details thereof will be described later. However, when schematically describing the operation, in a first embodiment of the invention, the rotation detection circuit 108 uses two kinds of reference threshold voltages Vinv and Vcomp, converts an induced current Ik generated in the drive coil 209 due to rotational free vibration of the stepping motor 107 to an induced voltage signal VRs using a detection element in a predetermined detection section T, and detects an induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp on the assumption that the induced voltage VRs is equivalent to an induced current Ik exceeding a predetermined reference value (first reference value or second reference value). That is, the rotation detection circuit 108 equivalently detects the induced current Ik exceeding the predetermined reference value (first reference value or second reference value) by detecting the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp in the detection section T.

In a second embodiment of the invention, the rotation detection circuit 108 uses one kind of reference threshold voltage Vcomp, converts an induced current Ik generated in the drive coil 209 due to rotational free vibration of the stepping motor 107 to an induced voltage signal VRs using a detection element in a predetermined detection section T, and detects an induced voltage signal VRs exceeding the reference voltage Vcomp on the assumption that the induced voltage signal VRs is equivalent to an induced current Ik exceeding a predetermined reference value. That is, the rotation detection circuit 108 equivalently detects the induced current Ik exceeding the predetermined reference value by detecting the induced voltage signal VRs exceeding the reference voltage Vcomp in the detection section T.

In addition, in a third embodiment of the invention, the rotation detection circuit 108 uses two kinds of reference threshold voltages Vinv and Vcomp similarly to the first embodiment, converts an induced current Ik generated in the drive coil 209 due to rotational free vibration of the stepping motor 107 to an induced voltage signal VRs using a detection element in a predetermined detection section T, and detects an induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp on the assumption that the induced voltage signal VRs is equivalent to an induced current Ik exceeding a predetermined reference value (first reference value or second reference value). That is, the rotation detection circuit 108 equivalently detects the induced current Ik exceeding the predetermined reference value (first reference value or second reference value) by detecting the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp in the detection section T.

In each embodiment of the invention, the reference voltages Vinv and Vcomp are set as follows. In a case where the rotor of the stepping motor 107 moves at a constant fast speed similarly to a case where the stepping motor 107 rotates, and the like, the reference voltages Vinv and Vcomp are set in order for the induced voltage signal VRs to exceed the reference voltages Vinv and Vcomp. In addition, in a case where the rotor of the stepping motor 107 does not move at a constant fast speed similarly to a case where the stepping motor 107 does not rotate, the reference voltages Vinv and Vcomp are set in order for the induced voltage signal VRs not to exceed the reference voltages Vinv and Vcomp.

The detection section determination circuit 109 compares detection times and sections of induced voltage signals VRs which are detected by the rotation detection circuit 108 and exceed the reference voltage Vinv or Vcomp to generate a pattern of the induced voltage signals VRs, and determines the degree of margin of the drive energy.

In this manner, the rotation detection circuit 108 detects the induced voltage signal VRs which is generated by the stepping motor 107 and exceeds the reference voltage Vinv or Vcomp (in other words, the induced current Ik exceeding a reference value). The detection section determination circuit 109 determines to which section in the detection section T the induced voltage signal VRs belongs, and determines the degree of drive margin of a drive pulse operated at that time on the basis of a pattern indicating the section to which the induced voltage signal VRs belongs.

The control circuit 103 carries out pulse control by outputting a main drive pulse control signal to the main drive pulse generation circuit 104 in order for the main drive pulse generation circuit 104 to carry out an operation of raising energy of the main drive pulse P 1 by one rank (pulse-up), an operation of lowering the energy of the main drive pulse P 1 by one rank (pulse-down), or retention of the main drive pulse P 1 without change on the basis of the pattern of the induced voltage signal VRs which is transmitted from the detection section determination circuit 109 . In addition, the control circuit 103 carries out pulse control in order for the correction drive pulse generation circuit 105 to output a correction drive pulse control signal for driving with the correction drive pulse P 2 .

The main drive pulse generation circuit 104 or the correction drive pulse generation circuit 105 outputs a drive pulse corresponding to the control signal to the motor driver circuit 106 , and the motor driver circuit 106 rotatably drives the stepping motor 107 by the drive pulse.

›DETAILED DESCRIPTION OF THE INVENTION · 4 of 28

FIG. 2 shows a configuration diagram of the stepping motor 107 that is used in each embodiment of the invention, and illustrates an example of a stepping motor for a timepiece that is generally used in an analog electronic timepiece.

In FIG. 2 , the stepping motor 107 includes a stator 201 having a rotor accommodation through-hole 203 , a rotor 202 that is rotatably disposed in the rotor accommodation through-hole 203 , a magnetic core 208 that is joined to the stator 201 , and a drive coil 209 wound around a magnetic core 208 . In a case where the stepping motor 107 is used in the analog electronic timepiece, the stator 201 and the magnetic core 208 are fixed and joined to a base plate (not shown) by a screw (not shown). The drive coil 209 has a first terminal OUT 1 , and a second terminal OUT 2 .

The rotor 202 is magnetized to two poles (S-pole and N-pole). A plurality of (two in this embodiment) notched portions (outer notches) 206 and 207 are provided to an outer end of the stator 201 formed from a magnetic material at positions opposite to each other with the rotor accommodation through-hole 203 interposed therebetween. Saturable portions 210 and 211 are provided between the respective notches 206 and 207 , and the rotor accommodation through-hole 203 .

The saturable portions 210 and 211 are configured in such a manner that the saturable portions 210 and 211 are not magnetically saturated by a magnetic flux of the rotor 202 , and are magnetically saturated when the drive coil 209 is excited, and thus magnetic resistance thereof increases. The rotor accommodation through-hole 203 is formed to have a circular hole shape in which a plurality of (two in this embodiment) semicircular notched portions (inner notches) 204 and 205 are integrally formed in a through-hole having a circular profile at positions opposite to each other.

The notched portions 204 and 205 constitute a positioning portion that determines a stop position of the rotor 202 . In a state in which the drive coil 209 is not excited, the rotor 202 stably stops at a position corresponding to the positioning portion as shown in FIG. 2 , in other words, at a position (position of an angle θ 0 ) at which a magnetic pole axis A of the rotor 202 is perpendicular to a line segment obtained by connecting the notched portions 204 and 205 . An XY coordinate space centering around a rotational axis (rotational center) of the rotor 202 is divided into four quadrants (a first quadrant I to a fourth quadrant IV).

When rectangular wave drive pulses are supplied from the motor driver circuit 106 to the terminals OUT 1 and OUT 2 of the drive coil 209 (for example, the first terminal OUT 1 is set as a positive electrode, and the second terminal OUT 2 is set as a negative electrode), and a drive current i is allowed to flow in an arrow direction of FIG. 2 , the magnetic flux is generated in the stator 201 in a dashed arrow direction. Accordingly, the saturable portions 210 and 211 are saturated, and thus the magnetic resistance increases. Then, the rotor 202 is rotated by 180° in the arrow direction of FIG. 2 by the interaction between the magnetic pole generated in the stator 201 and the magnetic pole generated in the rotor 202 , and thus the magnetic pole axis of the rotor 202 is stably stopped at a position of an angle θ 1 . In addition, a rotation direction (the counterclockwise direction in FIG. 2 ) to carry out a common operation (a hand movement operation of the analog electronic timepiece in this embodiment) by rotatably driving the stepping motor 107 is set as a forward direction, and the opposite direction (clockwise direction) of the rotation direction is set as a backward direction.

Next, when reversed-polarity rectangular wave drive pulses are supplied from the motor driver circuit 106 to the terminals OUT 1 and OUT 2 of the drive coil 209 (the first terminal OUT 1 is set as a negative electrode and the second terminal OUT 2 is set as a positive electrode to realize a polarity reversed to that of the above-described driving), and a drive current i is allowed to flow in the opposite direction of the arrow direction of FIG. 2 , a magnetic flux is generated in the stator 201 in a direction opposite to that of a dashed arrow. Accordingly, the saturable portions 210 and 211 are first saturated. Thereafter, the rotor 202 is rotated by 180° in the same direction (forward direction) as described above by the interaction between the magnetic pole generated in the stator 201 and the magnetic pole generated in the rotor 202 , and thus the magnetic pole axis of the rotor 202 is stably stopped at a position of an angle θ 0 .

In this manner, it is configured that the above-described operations are repetitively carried out to continuously rotate the rotor 202 by 180° in the arrow direction by supplying signals (alternating signals) having different polarity with respect to the drive coil 209 as described above.

The control circuit 103 rotatably drives the stepping motor 107 by alternately driving the stepping motor 107 by main drive pulses P 1 having different polarity, and in a case where rotation by each of the main drive pulses P 1 is impossible, the stepping motor 107 is rotatably driven by a correction drive pulse P 2 having the same polarity as the main drive pulse P 1 .

FIG. 3 shows a timing chart in a case where the stepping motor 107 is driven by the main drive pulse P 1 in a first embodiment of the invention. FIG. 3 collectively illustrates a degree of margin of energy of the main drive pulse P 1 with respect to a load, a rotation position of the rotor 202 of the stepping motor 107 , a pattern of the induced voltage signal VRs which represents a rotation state, and a pulse control operation.

FIG. 3 illustrates a state during normal driving (during a hand movement operation of time indicating hands 114 to 116 by the main drive pulse P 1 in a state in which a power supply voltage of the analog electronic timepiece is a rated voltage). In addition, in FIG. 3 , P 1 represents the main drive pulse P 1 , and a drive section in which the rotor 202 is rotatably driven by the main drive pulse P 1 . In addition, a to e are regions indicating rotation positions of the magnetic axis A of the rotor 202 during the driving with the main drive pulse P 1 .

›DETAILED DESCRIPTION OF THE INVENTION · 5 of 28

A predetermined time immediately after termination of the driving with the main drive pulse P 1 is set as a detection section T in which a rotation state is detected, and the detection section T is divided into a plurality of continuous sections (in the first embodiment, three sections T 1 to T 3 ). In this embodiment, a first predetermined time immediately after termination of the driving with the main drive pulse P 1 is set as a first section T 1 , a predetermined time subsequent to the first section T 1 is set as a second section T 2 , and a predetermined time subsequent to the second section T 2 is set as a third section T 3 .

When the XY coordinate space centering around the rotor 202 , in which the magnetic pole axis A of the rotor 202 is located by the rotation of the rotor 202 , is divided into a first quadrant I to a fourth quadrant IV, the section T 1 to the section T 3 may be expressed as follows.

For example, in a large-load-increment driving (small-margin rotation) state in which the rank of the main drive pulse P 1 is retained without being changed, the first section T 1 is a section in which a rotation state of the rotor 202 in a first forward region a in the second quadrant II is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II, and a rotation state of the rotor 202 in a first forward region b in the third quadrant III are determined, and the third section T 3 is a section in which a rotation state of the rotor 202 in a first backward region c in the third quadrant III is determined.

In addition, in an intermediate-load-increment driving (intermediate-margin rotation) state in which the main drive pulse P 1 is pulse-down controlled, the first section T 1 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II, and the rotation state of the rotor 202 in the first forward region b in the third quadrant III are determined, and the third section T 3 is a section in which the rotation state of the rotor 202 in the first backward region c in the third quadrant III is determined. The intermediate-load-increment driving (intermediate-margin rotation) state is a state in which energy of the main drive pulse P 1 with respect to a load is larger compared to the large-load-increment driving (small-margin rotation) state.

In addition, in a small-load-increment driving (large-margin rotation) state in which the main drive pulse P 1 is pulse-down controlled, the first section T 1 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III, and the rotation state of the rotor 202 in the first backward region c in the third quadrant III are determined, and the third section T 3 is a section in which the rotation state of the rotor 202 in the first backward region c in the third quadrant III is determined. The small-load-increment driving (large-margin rotation) state is a state in which energy of the main drive pulse P 1 with respect to a load is larger compared to the intermediate-load-increment driving (intermediate-margin rotation) state.

In addition, in a minimum-load-increment driving (maximum-margin rotation) state in which the main drive pulse P 1 is pulse-down controlled, the first section T 1 is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III, and the rotation state of the rotor 202 in the first backward region c in the third quadrant III are determined, and the third section T 3 is a section in which a state of the rotor 202 after the first backward region c in the third quadrant III is determined. The minimum-load-increment driving (maximum-margin rotation) state is a state in which energy of the main drive pulse P 1 with respect to a load is larger compared to the small-load-increment driving (large-margin rotation) state.

In addition, in a large-load-increment driving (limited rotation) state in which the main drive pulse P 1 is pulse-up controlled, the first section T 1 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II, and the rotation state of the rotor 202 in the first forward region b in the third quadrant III are determined, and the third section T 3 is a section in which the rotation state of the rotor 202 in the first backward region c in the third quadrant III is determined. The large-load-increment driving (limited rotation) state is a state in which energy of the main drive pulse P 1 with respect to a load is smaller compared to the large-load-increment driving (small-margin rotation) state.

In addition, in a state in which rotation does not occur by the driving with the main drive pulse P 1 (driving with a correction drive pulse P 2 and a maximum-load-increment driving (non-rotation) state in which the main drive pulse P 1 is pulse-up controlled), the first section T 1 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II is determined, the second section T 2 is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II, and a rotation state of the rotor 202 in a first backward region d in the second quadrant II and the first quadrant I are determined, and the third section T 3 is a section in which the rotation state of the rotor 202 in the first backward region d in the first quadrant I, and a rotation state of the rotor 202 in a second forward region e in the first quadrant I are determined. The maximum-load-increment driving (non-rotation) state is a state in which energy of the main drive pulse P 1 with respect to a load is smaller compared to the large-load-increment driving (limited rotation) state.

›DETAILED DESCRIPTION OF THE INVENTION · 6 of 28

A plurality of reference voltages (in the first embodiment, two kinds including the first reference voltage Vinv and the second reference voltage Vcomp) which detect the induced voltage signal VRs are prepared.

In the section T 1 , the induced voltage signal VRs, which corresponds to the induced current Ik flowing through the drive coil 209 in the same direction as the drive current i, is detected.

The section T 1 is a region in which the drive current i and the induced current Ik flow in the same direction as each other. When a load with respect to energy of the main drive pulse P 1 increases, rotation of the rotor 202 becomes slow, and thus a time at which the induced current is generated is delayed. A detection time of the induced current Ik generated before the section T 1 is delayed, and the induced current Ik is detected in the section T 1 .

That is, in a case where the load with respect to the energy of the main drive pulse P 1 is smaller than a predetermined value, in the section T 1 , the rotor 202 rotates at a speed higher than a constant speed, and thus an induced current Ik exceeding a predetermined value is not detected. When a load with respect to the energy of the main drive pulse increases more than the predetermined value, the rotation of the rotor 202 becomes slow in the section T 1 , and thus the induced current Ik exceeding the predetermined value is detected.

The first embodiment utilizes the phenomenon as described above, and is configured in such a manner that selection of a reference voltage to be used in the sections T 2 and T 3 is carried out on the basis of whether or not the induced voltage signals VRs exceeding a predetermined reference voltage are detected plural times (in this embodiment, two values including T 1 and T 1 next) in the section T 1 , and detection is carried out by changing the selection of the induced current Ik flowing in the same direction as the drive current i or a direction opposite to that of the drive current i, thereby carrying out determination of a rotation state, or pulse control.

In this manner, detection is carried out by changing polarity (detection direction) for detecting the induced current Ik in the sections T 2 and T 3 after the section T 1 on the basis of whether or not the induced current Ik exceeding a predetermined reference value is detected plural times in the first section T 1 , and the rotation state of the stepping motor 107 is detected on the basis of the induced current Ik in each of the sections T 1 to T 3 (actually, an induced voltage signal VRs equivalent to the induced current Ik). Accordingly, even when a load is large and the rotation of the rotor 202 is slow, rotation detection may be carried out at a stage in which the rotation of the rotor 202 is fast, and thus accurate rotation detection may be carried out by reducing an effect due to a load variation.

In addition, in a case where the rotation is slow, the rotation state may be accurately detected by setting the reference value to be small. In addition, in a case where the rotor 202 is rotated at a speed higher than a constant speed at which the induced current Ik exceeding a predetermined reference value may not be detected plural times in the first section T 1 , a sufficiently large induced voltage signal VRs may be detected even when the direction of the induced current Ik is not changed. Accordingly, a detection process is configured to be simple by carrying out the rotation detection on the basis of the induced signal VRs corresponding to the induced current Ik that flows in the same direction as the main drive pulse P 1 without changing the direction of the induced current Ik.

For example, in FIG. 3 , in the minimum-load-increment driving (maximum-margin rotation) state, the small-load-increment driving (large-margin rotation) state, and maximum-load-increment driving (non-rotation) state, only one induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 1 , and thus rotation detection in the subsequent sections T 2 and T 3 is carried out using the second reference voltage Vcomp.

On the other hand, in the intermediate-load-increment driving (intermediate-margin rotation) state, the large-load-increment driving (small-margin rotation) state, and the large-load-increment driving (limited rotation) state, an induced current exceeding each of a plurality of reference values is detected plural times (in this embodiment, two induced voltage signals VRs exceeding the first reference voltage Vinv, and one induced voltage signal VRs exceeding the second reference voltage Vcomp) in the section T 1 , and thus the subsequent rotation detection is configured to be carried out in sections T 2 R and T 3 R using the second reference voltage Vcomp. In addition, in FIG. 3 , a case of using the sections T 1 to T 3 is indicated by out 1 , and a case of using the sections T 2 R and T 3 R is indicated by out 2 .

As described above, a case in which the induced current Ik exceeding each of a plurality of reference values cannot be detected plural times in the section T 1 corresponds to either a case in which energy of the main drive pulse P 1 is sufficiently large and thus rotation is carried out without a problem, or a case in which the energy is insufficient and thus rotation is not carried out. Accordingly, rotation or non-rotation may be accurately detected without changing a subsequent rotation detection operation.

Conversely, a case in which the induced current Ik exceeding each of a plurality of reference values can be detected plural times in the section T 1 corresponds to a state in which it cannot be said that the energy of the main drive pulse P 1 is really insufficient, but it cannot be said that the energy is sufficiently large, and thus there is a concern that rotation becomes slow, and accurate determination of rotation may be difficult. However, the rotation detection in the subsequent sections T 2 and T 3 is configured in such a manner that rotation detection in the region c in a case where the drive current i and the induced current Ik flow in the same direction is changed to rotation detection in the region b in a case where the drive current i and the induced current Ik flow in directions opposite to each other by changing the detection direction of the induced current Ik as described above, thereby increasing rotation detection accuracy.

›DETAILED DESCRIPTION OF THE INVENTION · 7 of 28

FIG. 4 shows a determination chart in which pulse control operations in the first embodiment of the invention are arranged.

In FIG. 4 , T 1 represents the section T 1 and a determination value indicating whether or not a first induced voltage signal VRs exceeding the reference voltages Vinv or Vcomp is detected in the section T 1 . In addition, T 1 next represents a determination value indicating whether or not a second induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected in the section T 1 .

The sections T 1 , T 2 , and T 3 are sections in which detection is carried out when the drive current i and the induced current Ik flow in the same direction, and the sections T 2 R and T 3 R are sections in which the induced current Ik is detected by setting the detection direction to a direction opposite to that of the sections T 2 and T 3 . The sections T 2 and the section T 2 R have the same width and position, respectively, and the section T 3 and the section T 3 R have the same time width and position, respectively. That is, the sections T 2 and T 3 , and the sections T 2 R and T 3 R are different only in that the detection direction of the induced current Ik is reversed.

As described above, a case in which the induced voltage signal VRs exceeding the first reference voltage Vinv or the second reference voltage Vcomp is detected is expressed by a determination value “1”, and a case in which the induced voltage signal VRs exceeding the first reference voltage Vinv or the second reference voltage Vcomp is not detected is expressed by a determination value “0”, respectively. In addition, “1/0” represents that the determination value may be either “1” or “0”. In addition, “-” represents that the determination value is not considered as a pattern of the induced voltage signal VRs.

In a case of a pattern using the sections T 1 , T 2 , and T 3 , the pattern of the induced voltage signal VRs is expressed by a determination value (T 1 ) indicating whether or not the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected for the first time in the section T 1 , a determination value (T 1 next) indicating whether or not the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected for the second time in the section T 1 , a determination value (T 2 ) indicating whether or not the induced voltage signal VRs exceeding the second reference voltage Vcomp is detected in the section T 2 , and a determination value (T 3 ) indicating whether or not the induced voltage signal VRs exceeding the second reference voltage Vcomp is detected in the section T 3 .

In a case of a pattern using the section T 1 , T 2 R, and T 3 R, the pattern of the induced voltage signal VRs is expressed by a determination value (T 1 ) indicating whether or not the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected for the first time in the section T 1 , a determination value (T 1 next) indicating whether or not the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is detected for the second time in the section T 1 , a determination value (T 2 R) indicating whether or not the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 2 R, and a determination value (T 3 R) indicating whether or not the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 3 R.

The rotation detection circuit 108 detects whether or not the induced voltage signal VRs exceeding the reference voltage Vinv or Vcomp is present, the detection section determination circuit 109 determines the pattern (representing the degree of margin of the energy of the main drive pulse P 1 ) of the induced voltage signal VRs, and the control circuit 103 carries out the following pulse control such as pulse-up or pulse-down of the main drive pulse P 1 , and driving with the correction drive pulse P 2 on the basis of the pattern with reference to the determination chart of FIG. 4 which is stored inside the control circuit 103 , thereby rotatably controlling the stepping motor 107 .

FIG. 5 shows a partially detailed circuit diagram used in the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first and third embodiments of the invention. FIG. 5 shows a partially detailed circuit diagram of the motor driver circuit 106 and the rotation detection circuit 108 .

A detailed operation will be described later, but a switch control circuit 303 allows the transistors Q 2 and Q 3 , or the transistors Q 1 and Q 4 to simultaneously enter an On-state in response to a control signal Vi supplied from the main drive pulse generation circuit 104 or the correction drive pulse generation circuit 105 during rotation driving to supply a drive current to the drive coil 209 in a normal direction or a reverse direction, thereby rotatably driving the stepping motor 107 .

In addition, in each embodiment of the invention, as the main drive pulse P 1 and the correction drive pulse P 2 , drive pulses having a waveform (comb-like shape) in which a supply state of supplying drive energy and a supply stop state of stopping supply of the drive energy are alternately repeated at a predetermined cycle are used.

In addition, the switch control circuit 303 controls transistors Q 3 to Q 6 to have any one of an ON-state, an OFF-state, and a switching state during rotation detection in order for an induced voltage signal VRs to be generated in a first detection resistor 301 or a second detection resistor 302 .

The transistors Q 1 and Q 2 are constituent elements of the motor driver circuit 106 , and the transistors Q 5 and Q 6 , and detection resistors 301 and 302 are constituent elements of the rotation detection circuit 108 . The transistors Q 3 and Q 4 , and the switch control circuit 303 are constituent elements that are commonly used in both of the motor driver circuit 106 and the rotation detection circuit 108 . In addition, the detection resistors 301 and 302 , a comparator 304 , inverters 305 and 306 , and a NAND circuit 307 are constituent elements of the rotation detection circuit 108 . The detection resistors 301 and 302 are elements having the same resistance value, and constitute a detection element. In addition, the transistors Q 1 to Q 6 have small on-resistance in an ON-state, respectively, and constitute a low-impedance element. The detection resistors 301 and 302 have on-resistance larger than that of the transistors Q 1 to Q 6 , and constitute a high-impedance element.

›DETAILED DESCRIPTION OF THE INVENTION · 8 of 28

The second reference voltage Vcomp is configured to be input to a reference signal input portion of the comparator 304 , and induced voltage signals VRs detected by the detection resistors 301 and 302 are configured to be input to first and second input portions of the comparator 304 , respectively. In a case where the induced voltage signal VRs exceeding the second reference voltage Vcomp is generated in the detection resistor 301 or 302 , a detection signal Vs of a high-level signal “1” is output to detection section determination circuit 109 from the comparator 304 .

In addition, threshold values of the inverters 305 and 306 are set to the first reference voltage Vinv, respectively. In a case where the induced voltage signal VRs exceeding the first reference voltage Vinv is generated in the detection resistor 301 , a low-level signal “0” is output from the inverter 306 to the detection section determination circuit 109 , and a detection signal Vs of a high level “1” is output from the NAND circuit 307 to the detection section determination circuit 109 . In a case where the induced voltage signal VRs exceeding the first reference voltage Vinv is generated in the detection resistor 302 , the low-level signal “0” is output from the inverter 305 to the detection section determination circuit 109 , and the detection signal Vs of the high level “1” is output from the NAND circuit 307 to the detection section determination circuit 109 .

The detection section determination circuit 109 selects the detection signal Vs transmitted from the comparator 304 or the NAND circuit 307 in response to a detection direction of the induced current Ik or the reference voltages Vinv and Vcomp that are used, and determines to which one of the sections T 1 to T 3 , T 2 R, and T 3 R the induced voltage signal VRs belongs.

FIG. 6 shows a timing chart of the first embodiment of the invention in a case where detection is carried out without changing a detection direction of the induced current Ik. FIG. 6 shows a timing chart of the small-load-increment driving (large-margin rotation) state, and illustrates a timing during detection in a state (sections T 1 , T 2 , and T 3 ) in which the induced current Ik flows in the same direction as the drive current i.

In a case where the stepping motor 107 is rotatably driven, in a drive period P 1 between times ta and tb, the switch control circuit 303 repetitively switches the transistor Q 2 between an ON-state (supply state) and an OFF-state (supply stop state) at a predetermined cycle while maintaining the transistor Q 3 in an ON-state to generate a comb-like main drive pulse P 1 , and supplies the drive current i in an arrow direction of FIG. 6 to the drive coil 209 of the stepping motor 107 . According to this, in a case where the stepping motor 107 rotates, the rotor 202 rotates in a forward direction by 180°.

On the other hand, detection of a rotation state is carried out in a detection section T from the termination time tb of the drive period P 1 of the main drive pulse P 1 to time tc.

That is, in the section T 1 starting from the time tb, the switch control circuit 303 switches the transistor Q 4 between an ON-state and an OFF-state at a predetermined cycle while maintaining the transistors Q 3 and Q 6 in an ON-state to allow the induced current Ik to flow to the detection resistor 302 in the same direction as the drive current i. According to this, the induced voltage signal VRs is generated in the detection resistor 302 .

The comparator 304 compares the induced voltage signal VRs and the second reference voltage Vcomp. When the induced voltage signal VRs exceeds the second reference voltage Vcomp, the comparator 304 outputs “1” to detection section determination circuit 109 as the detection signal Vs. When the induced voltage signal VRs does not exceed the second reference voltage Vcomp, the comparator 304 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

In addition, when the induced voltage signal VRs exceeds the first reference voltage Vinv, the inverter 305 outputs “0”, and when the induced voltage signal VRs does not exceed the first reference voltage Vinv, the inverter 305 outputs “1”. The NAND circuit 307 outputs an inverted signal “1” or “0” to the detection section determination circuit 109 as the detection signal Vs.

The detection section determination circuit 109 determines whether or not a plurality of induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, two induced voltage signals VRs exceeding at least the first reference voltage Vinv) are detected in the section T 1 on the basis of detection signals Vs transmitted from the comparator 304 and the NAND circuit 307 .

In an example of FIG. 6 , since a plurality of the induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 , even in the sections T 2 and T 3 , the switch control circuit 303 of the rotation detection circuit 108 carries out the detection operation without changing a flow direction of the induced current Ik. Accordingly, even in the sections T 2 and T 3 , each transistor is drive-controlled to carryout the same operation as described above.

In this case, in the sections T 2 and T 3 , a determination value of the induced voltage signal VRs, which is obtained by carrying out determination using the second reference voltage Vcomp without using the first reference voltage Vinv, is only used. That is, although the detection signal Vs is input to the detection section determination circuit 109 from both of the NAND circuit 307 and the comparator 304 , in the sections T 2 and T 3 , the detection section determination circuit 109 carries out determination only on whether or not the detection signal Vs input from the comparator 304 belongs to the section T 2 or T 3 . According to this, even in a non-rotation state in which a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 , determination is carried out using the second reference voltage Vcomp with a high level, and thus determination of the rotation state may be carried out more accurately. In addition, since the detection direction of the induced current Ik is not changed, the detection operation becomes simple.

›DETAILED DESCRIPTION OF THE INVENTION · 9 of 28

As a determination result, the detection section determination circuit 109 outputs a pattern (a first determination value in the section T 1 , a next determination value (T 1 next) in the section T 1 , a determination value in the section T 2 , and a determination value in the section T 3 ) of the induced voltage signal VRs to the control circuit 103 .

The control circuit 103 determines the rotation state of the stepping motor 107 with reference to the determination chart of FIG. 4 on the basis of the pattern output from the detection section determination circuit 109 , and carries out pulse control such as pulse-down, and pulse-up+driving with the correction drive pulse P 2 .

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 even in a next cycle after the cycle shown in FIG. 6 is terminated, each of the transistors Q 1 to Q 6 is drive-controlled to carry out the same operation. That is, the transistor Q 4 enters an ON-state in place of the transistor Q 3 , and the transistor Q 1 is switched in place of the transistor Q 2 at the same cycle as the transistor Q 2 , and thus driving with a comb-like main drive pulse P 1 having polarity reversed to the previous cycle is carried out. In addition, in the detection section T, the transistor Q 3 is switched in place of the transistor Q 4 at the same cycle as the transistor Q 4 , and the transistors Q 4 and Q 5 are driven to an ON-state in place of the transistors Q 3 and Q 6 . According to this, rotation detection based on the induced current Ik is carried out.

The induced voltage signal VRs, which is generated due to rotation of the stepping motor 107 , is generated in the detection resistor 301 , and the comparator 304 outputs a result obtained by comparing the induced voltage signal VRs and the second reference voltage Vcomp to the detection section determination circuit 109 as the detection signal Vs. In addition, the inverter 306 compares the induced voltage signal VRs and the first reference voltage Vinv, and outputs “1” or “0” in response to the comparison result. The NAND circuit 307 outputs an inverted signal “0” or “1” to the detection section determination circuit 109 as the detection signal Vs.

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 , the same operation as described above is carried out, and in the sections T 2 and T 3 , similarly to the previous cycle, the detection section determination circuit 109 carries out section determination only with respect to the detection signal Vs transmitted from the comparator 304 .

The detection section determination circuit 109 outputs a pattern (a first determination value in the section T 1 , a next determination value (T 1 next) in the section T 1 , a determination value in the section T 2 , and a determination value in the section T 3 ) of the induced voltage signal VRs to the control circuit 103 .

The control circuit 103 determines the rotation state of the stepping motor 107 on the basis of the pattern output from the detection section determination circuit 109 , and carries out pulse control such as pulse-down, and pulse-up+driving with the correction drive pulse P 2 .

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 , rotation control of the stepping motor 107 is carried out by alternately repeating the above-described two cycles.

FIG. 7 shows a timing chart of the first embodiment of the invention in a case where detection is carried out by changing the detection direction of the induced current Ik. FIG. 7 illustrates a timing in a large-load-increment driving (small-margin rotation) state. In FIG. 7 , to carry out detection by changing the detection direction of the induced current Ik to an opposite direction in the sections T 2 R and T 3 R, detection is carried out by inverting the polarity of the induced voltage signal VRs. According to this, the detection of the induced voltage signal VRs is configured to be carried out in the region b earlier in time instead of the region c later in time as shown in FIG. 6 so as to carryout the rotation detection with relatively high accuracy even when rotation is slow.

In a case where the stepping motor 107 is rotatably driven, in a drive period P 1 between times ta and tb, the switch control circuit 303 repetitively switches the transistor Q 2 between an ON-state (supply state) and an OFF-state (supply stop state) at a predetermined cycle while maintaining the transistor Q 3 in an ON-state to supply the drive current i in an arrow direction of FIG. 5 to the drive coil 209 of the stepping motor 107 with the comb-like main drive pulse P 1 . According to this, in a case where the stepping motor 107 rotates, the rotor 202 rotates in a forward direction by 180°.

On the other hand, detection of a rotation state is carried out in a detection section T from the termination time tb of the drive period P 1 of the main drive pulse P 1 to time tc.

›DETAILED DESCRIPTION OF THE INVENTION · 10 of 28

The detection section determination circuit 109 determines whether or not a plurality of induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 on the basis of detection signals Vs transmitted from the comparator 304 and the NAND circuit 307 . That is, the detection section determination circuit 109 determines whether or not rotation of the rotor 202 is slower than a predetermined speed in the section T 1 .

In an example of FIG. 7 , since a plurality of the induced voltage signals VRs exceeding the predetermined reference voltage (in this embodiment, two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 (in a state in which the rotation of the rotor 202 is slow), the switch control circuit 303 operates so that the detection is carried out by changing the detection direction of the induced current Ik to an opposite direction in sections (section T 2 R and section T 3 R) that are continuous with the section T 1 .

In the sections T 2 R and T 3 R, the switch control circuit 303 switches the transistor Q 3 between an ON-state and an OFF-state at a predetermined cycle while maintaining the transistors Q 4 and Q 5 in an ON-state, and the transistor Q 6 in an OFF-state in order for the induced current Ik to flow to the detection resistor 301 . In the detection resistor 301 , the induced voltage signal VRs in which the detection direction is opposite to that of the sections T 2 and T 3 is generated, and thus detection of the induced current Ik in which the detection direction is changed to the opposite direction is carried out. According to this, the detection of the induced voltage signal VRs generated in the region b is carried out.

In addition, when the induced voltage signal VRs exceeds the first reference voltage Vinv, the inverter 306 outputs “0”, and when the induced voltage signal VRs does not exceed the first reference voltage Vinv, the inverter 306 outputs “1”. The NAND circuit 307 outputs an inverted signal “1” or “0” to the detection section determination circuit 109 as the detection signal Vs.

In the sections T 2 R and T 3 R, rotation is slow and the level of the induced signal VRs is low, and thus a determination value of the induced voltage signal VRs, which is obtained by carrying out determination using the first reference value Vinv without using the second reference voltage Vcomp is only used so as to increase detection sensitivity. That is, although the detection signal Vs is input to the detection section determination circuit 109 from both of the NAND circuit 307 and the comparator 304 , in the sections T 2 R and T 3 R, the detection section determination circuit 109 carries out determination only on whether or not the detection signal Vs input from the NAND circuit 307 belongs to the section T 2 R or T 3 R.

The control circuit 103 determines the rotation state of the stepping motor 107 on the basis of the pattern transmitted from the detection section determination circuit 109 , and carries out pulse control such as pulse-down, retention, and pulse-up.

As described above, in a case where it is determined that the energy of the main drive pulse P 1 with respect to a load is small, and the rotation of the rotor 202 is slow in the section T 1 , in sections after the section T 1 , detection is carried out after changing the detection direction of the induced current Ik to an opposite direction, and determination of the rotation state is carried out, whereby rotation detection in a stage in which the rotation of the rotor is fast (the rotation region b of the rotor 202 ) is possible, and thus the rotation state may be detected more accurately. In addition, even in a case where the rotation of the rotor 202 is slow, and the level of the induced voltage signal VRs is low, since a plurality of the induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 , stable stopping at a position perpendicular to a line segment connecting the notched portion 204 and 205 is possible in a reliable manner, and the first reference voltage Vinv that is a relatively low reference voltage is used, and thus determination of the rotation state may be carried out in a relatively accurate manner.

In a case where a plurality of induced voltage signals VRs exceeding a plurality of predetermined reference voltages Vinv and Vcomp are detected in the section T 1 even in a next cycle after the cycle shown in FIG. 7 is terminated, each of the transistors Q 1 to Q 6 is drive-controlled to carry out the same operation as described above. That is, the transistor Q 4 enters an ON-state in place of the transistor Q 3 , and the transistor Q 1 is switched in place of the transistor Q 2 at the same cycle as the transistor Q 2 , and thus driving with a comb-like main drive pulse P 1 having polarity reversed to the previous cycle is carried out.

›DETAILED DESCRIPTION OF THE INVENTION · 11 of 28

In the section T 1 of the detection section T, the transistor Q 3 is switched in place of the transistor Q 4 at the same cycle as the transistor Q 4 , and the transistors Q 4 and Q 5 are driven to an ON-state in place of the transistors Q 3 and Q 6 . According to this, the induced current Ik flows to the detection resistor 301 in the same direction as the drive current i, and thus the induced voltage signal VRs is generated in the detection resistor 301 . According to this, rotation detection based on the induced current Ik flowing in the same direction as the drive current i is carried out.

In addition, in the sections T 2 R and T 3 R, the transistor Q 4 is switched between an ON-state and an OFF-state in place of the transistor Q 3 at a predetermined cycle while maintaining the transistors Q 3 and Q 6 in an ON-state in place of the transistors Q 4 and Q 5 , and the induced current Ik is allowed to flow to the detection resistor 302 . The induced voltage signal VRs is generated in the detection resistor 302 . According to this, detection of the induced current Ik in which the detection direction is changed to an opposite direction is carried out.

Similarly to the previous cycle, with regard to the induced voltage signal VRs generated due to rotation of the stepping motor 107 , in the section T 1 , a determination value may be obtained on the basis of the first reference voltage Vinv and the second reference voltage Vcomp, and in the sections T 2 R and T 3 R, the determination value may be obtained only on the basis of the first reference voltage Vinv.

In a case where a plurality of induced voltage signals VRs exceeding a predetermined reference voltage Vinv are detected in the section T 1 , rotation control of the stepping motor 107 is carried out by alternately repeating the above-described two cycles.

The rotation driving operation, the rotation detection operation, and the pulse control operation which correspond to the magnitude of energy of the main drive pulse P 1 with respect to a load are carried out by a combination of the above-described four cycles.

FIG. 8 shows a flowchart illustrating the operation of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the first embodiment of the invention. The flowchart mainly illustrates a process of the control circuit 103 .

Hereinafter, an operation of the first embodiment of the invention will be described in detail with reference to FIGS. 1 to 8 .

In FIG. 1 , the oscillation circuit 101 generates a reference clock signal of a predetermined frequency, and the frequency dividing circuit 102 frequency-divides the signal generated in the oscillation circuit 101 to generate a timepiece signal serving as a reference of time counting, and outputs the resultant timepiece signal to the control circuit 103 .

The control circuit 103 carries out a time counting operation by counting the timepiece signal, and first of all, resets an energy rank n of the main drive pulse P 1 n , and a counted value N indicating the number of times of continuous driving with the same main drive pulse P 1 to 0 (step S 501 in FIG. 8 ).

The control circuit 103 carries out initial setting to allow the rotation detection circuit 108 to carryout rotation detection on the basis of the induced current Ik (in other words, the induced voltage signal VRs) flowing in the same direction as the drive current i (setting to Rs-N) (step S 502 ).

Next, the control circuit 103 outputs a main drive pulse control signal so as to rotatably drive the stepping motor 107 with a main drive pulse P 10 having the minimum energy which is set in process step S 501 (steps S 503 and S 504 ).

The main drive pulse generation circuit 104 outputs the main drive pulse P 10 corresponding to the control signal to the motor driver circuit 106 in response to the control signal output from the control circuit 103 . The motor driver circuit 106 rotatably drives the stepping motor 107 with the main drive pulse P 10 . The motor driver circuit 106 rotatably drives the stepping motor 107 with the main drive pulse P 10 . The stepping motor 107 is rotatably driven with main drive pulse P 10 , and rotatably drives the time indicating hands 114 to 116 of the analog display portion 112 . According to this, in a case where the stepping motor 107 is normally rotated, a current time is displayed at any time in the analog display portion 112 by the time indicating hands 114 to 116 . In addition, in a case where a calendar display portion (not shown) is rotatably driven by the stepping motor 107 , calendar display is changed to display of the next day.

The rotation detection circuit 108 detects whether or not the induced current Ik that flows in the same direction as the drive current i and exceeds a predetermined reference value is present. In other words, the rotation detection circuit 108 determines whether or not a plurality of induced voltage signals VRs exceeding a plurality of predetermined reference voltages Vinv and Vcomp are detected in the section T 1 . That is, first, as described with reference to FIGS. 6 and 7 , the rotation detection circuit 108 detects the induced voltage signal VRs while allowing the induced current Ik to flow in the same direction as the drive current i. The control circuit 103 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the first reference voltage Vinv (step S 505 ).

›DETAILED DESCRIPTION OF THE INVENTION · 12 of 28

In process step S 505 , in a case where it is determined that the induced signal exceeding the first reference voltage Vinv is not detected, in subsequent sections, as shown in FIG. 6 , the control circuit 103 controls the rotation detection circuit 108 to determine whether or not an induced voltage signal VRs exceeding the second reference voltage Vcomp is detected while retaining the detection direction of the induced current Ik without change. The detection section determination circuit 109 determines to which one of the sections T 2 and T 3 the induced voltage signal VRs exceeding the second reference voltage Vcomp, which is detected by the rotation detection circuit 108 , belongs.

The control circuit 103 determines whether or not the induced voltage signal VRs exceeding the second reference voltage Vcomp is detected in the section T 2 (step S 506 ). In a case where it is determined that the induced voltage signal VRs exceeding the second reference voltage Vcomp is not detected in the section T 2 , the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the second reference voltage Vcomp is detected in the section T 3 (step S 507 ).

In process step S 507 , in a case where it is determined that the induced voltage signal VRs exceeding the second reference voltage Vcomp is not detected in the section T 3 (this corresponds to a case of maximum-load-increment driving (not-rotation)), the control circuit 103 outputs a control signal to the correction drive pulse generation circuit 105 for driving with the correction drive pulse P 2 (step S 508 ). The correction drive pulse generation circuit 105 outputs the correction drive pulse P 2 to the motor driver circuit 106 in response to the control signal output from the control circuit 103 . The motor driver circuit 106 forcibly rotates the stepping motor 107 with the correction drive pulse P 2 .

Next, in a case where the rank n of the energy of the main drive pulse P 1 driven at this time (the main drive pulse of process step S 504 ) is not the maximum rank m (step S 509 ), the control circuit 103 carries out pulse-up of the rank n of the main drive pulse P 1 to be driven next time by one rank, and returns to process step S 502 (step S 510 ). In process step S 504 of next time, the main drive pulse generation circuit 104 carries out rotation driving with the main drive pulse P 1 (n+1) pulsed-up by one rank pulse.

In process step S 509 , in a case where the rank n of the main drive pulse P 1 is determined as the maximum rank m, since the rank n of the main drive pulse P 1 may not be raised and rotation may not be carried out, the control circuit 103 sets the rank of the main drive pulse P 1 to a main drive pulse P 1 (n−a) by lowering the rank by a predetermined rank a for electric power saving, and then returns to process step S 502 . (step S 511 ).

In a case where it is determined that the induced voltage signal VRs exceeding the second reference voltage Vcomp is detected in the section T 2 in process step S 506 (this corresponds to a case of minimum-load-increment (maximum-margin rotation)), the control circuit 103 determines whether or not the main drive pulse P 1 has the lowest rank 0 (step S 530 ).

In process step S 530 , in a case where it is determined that the rank n of the main drive pulse P 1 is not the lowest rank 0, the control circuit 103 adds 1 to a count number N of the number of times of continuous driving (step S 532 ), and determines whether or not the counted value N reaches a predetermined number of times (in the first embodiment, 80 times) (step S 533 ).

In process step S 533 , in a case where it is determined that the predetermined number of times is not reached, the control circuit 103 returns to process step S 502 without changing the rank n of the main drive pulse P 1 (step S 531 ). In a case where it is determined that the predetermined number of times is reached, the control circuit 103 carries out pulse-down of the rank n of the main drive pulse P 1 by one rank, and resets the counted value N to 0, and returns to process step S 502 (step S 534 ).

In process step S 530 , in a case where it is determined that the main drive pulse P 1 is the lowest rank 0, the control circuit 103 transitions to process step S 531 , and returns to process step S 502 without changing the rank n of the main drive pulse P 1 .

On the other hand, in process step S 505 , in a case where the rotation detection circuit 108 determines that the induced voltage signal VRs exceeding the first reference voltage Vinv is detected, the control circuit 103 determines whether or not the induced voltage signal VRs exceeds the second reference voltage Vcomp (step S 520 ).

In a case where it is determined that the induced voltage signal VRs does not exceed the second reference voltage Vcomp in process step S 520 , the control circuit 103 transitions to process step S 506 .

In process step S 520 , when it is determined that the induced voltage signal VRs exceeds the second reference voltage Vcomp, the control circuit 103 determines whether of not an induced voltage signal VRs (T 1 next) subsequently detected by the rotation detection circuit 108 exceeds the first reference voltage Vinv in the section T 1 (step S 521 ).

In process step S 521 , when it is determined that the induced voltage signal VRs (T 1 next) subsequently detected does not exceed the first reference voltage Vinv in the section T 1 , the control circuit 103 transitions to process step S 506 .

In process step S 521 , in a case where it is determined that the induced voltage signal VRs (T 1 next) subsequently detected exceeds the first reference voltage Vinv in the section T 1 (this corresponds to a case in which a plurality of induced voltage signals VRs exceeding a plurality of reference voltages are detected), as described with reference to FIG. 7 , the control circuit 103 carries out control in order for the rotation detection circuit 108 to carry out rotation detection after changing the detection direction of the induced current Ik (in other words, induced voltage signal VRs) to the opposite direction (setting to Rs-R) (step S 522 ).

›DETAILED DESCRIPTION OF THE INVENTION · 13 of 28

As described with reference to FIG. 7 , in the sections T 2 R and T 3 R, the rotation detection circuit 108 detects whether or not the induced voltage signal VRs exceeding the first reference voltage Vinv is present after changing the detection direction of the induced current Ik to the opposite direction by changing the detection resistors 301 and 302 . The detection section determination circuit 109 determines whether or not the induced voltage signal VRs, which is detected by the rotation detection circuit 108 and exceeds the first reference voltage Vinv, belongs to the sections T 2 R or T 3 R, and outputs a pattern of the induced voltage signal VRs to the control circuit 103 .

That is, the control circuit 103 determines whether or not the induced voltage signal VRs subsequently detected exceeds the second reference voltage Vcomp in the section T 1 (step S 523 ). In a case where it is determined that the induced voltage signal VRs subsequently detected exceeds the second reference voltage Vcomp, the control circuit 103 determines whether or not another induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 2 R (step S 525 ).

In process step S 525 , when it is determined that another induced voltage signal VRs exceeding the first reference voltage Vinv is not detected in the section T 2 R, the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 3 R (step S 526 ).

In process step S 526 , in a case where it is determined that the induced voltage signal VRs exceeding the first reference voltage Vinv is not detected in the section T 3 R (this corresponds to a case of maximum-load-increment driving (non-rotation), the control circuit 103 transitions to process step S 508 . In a case where it is determined that the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 3 R (this corresponds to a case of maximum-load-increment driving (limited rotation), the control circuit 103 transitions to process step S 509 .

In process step S 525 , it is determined that the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 2 R (this corresponds to a case of large-load-increment driving (small-margin rotation)), the control circuit 103 transitions to process step S 531 .

In process step S 523 , in a case where it is determined that the induced voltage signal VRs subsequently detected does not exceed the second reference voltage Vcomp, the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 2 R (step S 524 ).

In process step S 524 , in a case where it is determined that the induced voltage signal VRs exceeding the first reference voltage Vinv is not detected in the section T 2 R, the control circuit 103 transitions to process step S 526 . In a case where it is determined that the induced voltage signal VRs exceeding the first reference voltage Vinv is detected in the section T 2 R (this corresponds to a case of intermediate-load-increment driving (intermediate-margin rotation)), the control circuit 103 transitions to process step S 530 .

The rotation driving of the stepping motor 107 is carried out by selecting the drive pulse P 1 or P 2 with energy corresponding to the rotation state of the stepping motor 107 by repetitively carrying out the above-described process.

As described above, the stepping motor control circuit according to the first embodiment of the invention includes: a rotation detection unit that detects an induced current Ik flowing through a drive coil 209 due to free vibration of a stepping motor 107 in a detection section T divided into a plurality of sections T 1 to T 3 , and detects a rotation state of the stepping motor 107 on the basis of a pattern indicating whether or not an induced current Ik exceeding a predetermined reference value Vinv is detected in each of the sections T 1 to T 3 by using a phenomenon in which a detection time of the induced current Ik is delayed along with a relative load increase with respect to drive energy, and a level of the induced current Ik decreases; and a control unit that selects a drive pulse corresponding to the rotation state that is detected by the rotation detection unit among a plurality of kinds of drive pulses, each having different energy, and supplies a drive current i to the drive coil 209 by the selected drive pulse to rotatably drive the stepping motor 107 . The rotation detection unit carries out the detection by selecting a detection direction of the induced current Ik in sections T 2 and T 3 after a first section T 1 on the basis of whether or not the induced current Ik exceeding a predetermined reference value Vinv is detected in the first section T 1 that is an initial section of the detection section T, and detects the rotation state of the stepping motor 107 by a pattern based on the induced current Ik detected in each of the sections T 1 to T 3 .

Here, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the predetermined reference value Vinv is detected in the first section T 1 , in sections T 2 and T 3 after the first section T 1 , the rotation detection unit carries out the detection by selecting a first direction as the detection direction of the induced current Ik in the sections T 2 and T 3 after the first section T 1 , and in a case where the induced current Ik exceeding the predetermined reference value Vinv is not detected in the first section T 1 , in the sections T 2 and T 3 after the first section T 1 , the rotation detection unit carries out the detection by selecting a second direction opposite to the first direction as the detection direction of the induced current Ik, and detects the rotation state of the stepping motor 107 by a pattern based on the induced current Ik detected in each of the sections T 1 to T 3 .

›DETAILED DESCRIPTION OF THE INVENTION · 14 of 28

In addition, the rotation detection unit may be configured as follows. The rotation detection unit carries out the detection by selecting the detection direction of the induced current Ik in the sections T 2 and T 3 after the first section T 1 on the basis of whether or not the induced current Ik exceeding the predetermined reference value Vinv is detected plural times in the first section T 1 that is an initial section of the detection section T, and detects the rotation state of the stepping motor 107 by a pattern based on the induced current Ik detected in each of the sections T 1 to T 3 .

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding a predetermined reference value Vinv is detected plural times in the first section T 1 that is an initial section of the detection section T, in sections T 2 and T 3 after the first section T 1 , the rotation detection unit carries out the detection by changing the detection direction of the induced current Ik to a direction opposite to the direction of the first section T 1 , and detects the rotation state of the stepping motor 107 by a pattern based on the induced current Ik detected in each of the sections T 1 to T 3 .

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the predetermined reference value Vinv is not detected plural times in the first section T 1 that is an initial section of the detection section T, in the sections T 2 and T 3 after the first section T 1 , the rotation detection unit detects the induced current Ik by setting the detection direction to the same direction as the first section T 1 , and detects the rotation state of the stepping motor 107 by a pattern based on the induced current Ik detected in each of the sections T 1 to T 3 .

In addition, the rotation detection unit may be configured to carry out the detection in the first section T 1 by allowing the drive current i and the induced current Ik flow in the same direction.

In addition, the rotation detection unit may be configured in such a manner that as the plurality of reference values, a first reference value Vinv and a second reference value Vcomp larger than the first reference value Vinv are set.

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the first reference value is detected plural times in the first section T 1 that is an initial section of the detection section T, in the sections T 2 and T 3 after the first section T 1 , the rotation detection unit detects the induced current Ik on the basis of the first reference value.

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the first reference value is not detected plural times in the first section T 1 that is an initial section of the detection section T, in the sections T 2 and T 3 after the first section T 1 , the rotation detection unit detects the induced current Ik on the basis of the second reference value.

In addition, the detection section T is divided into the first section T 1 immediately after driving with the main drive pulse P 1 , a second section T 2 after the first section T 1 , and a third section T 3 after the second section T 2 . In a state in which the stepping motor 107 is driven while retaining a rank n of the drive pulse, the first section T 1 is a section in which a first forward rotation state of the rotor 202 in a second quadrant II of a space centering around the rotor 202 of the stepping motor 107 is determined, the second section T 2 is a section in which the first forward rotation state of the rotor 202 in the second quadrant II, and a first forward rotation state of the rotor 202 in a third quadrant III are determined, and the third section T 3 is a section in which a first backward rotation state of the rotor 202 in the third quadrant III is determined. In a case where the induced current Ik exceeding the first reference value in the first section T 1 is detected plural times, the rotation detection unit may be configured to detect the induced current Ik using the first reference value in the second section T 2 and the third section T 3 .

In addition, the detection section T is divided into a first section T 1 immediately after driving with the main drive pulse P 1 , a second section T 2 after the first section T 1 , and a third section T 3 after the second section T 2 . In a state in which the stepping motor 107 is driven while retaining a rank n of the main drive pulse P 1 , the first section T 1 is a section in which a first forward rotation state of the rotor 202 in a second quadrant II of a space centering around the rotor 202 of the stepping motor 107 is determined, the second section T 2 is a section in which the first forward rotation state of the rotor 202 in the second quadrant II, and a first forward rotation state of the rotor 202 in a third quadrant III are determined, and the third section T 3 is a section in which a first backward rotation state of the rotor 202 in the third quadrant III is determined. In a case where the induced current Ik exceeding the first reference value is not detected plural times in the first section T 1 , the rotation detection unit may be configured to detect the induced current Ik using the second reference value in the second section T 2 and the third section T 3 .

In addition, the rotation detection unit may be configured as follows. The rotation detection unit includes first and second detection resistors 301 and 302 that detect induced currents Ik flowing through the drive coil 209 due to free vibration of the stepping motor 107 in directions opposite to each other, and detects the induced current Ik in the detection section T by alternately repeating a first closed circuit including the drive coil 209 of the stepping motor 107 and the detection resistor 301 or 302 , and a second closed circuit constituted by the drive coil 209 and a low-impedance element. In addition, the rotation detection unit carries out the detection by changing the detection resistor constituting the first closed circuit to the first detection resistor 301 or the second detection resistor 302 in response to the direction of the induced current Ik that is detected.

›DETAILED DESCRIPTION OF THE INVENTION · 15 of 28

Accordingly, according to the stepping motor control circuit according to the embodiment of the invention, an effect of a load variation is reduced, and thus accurate rotation detection may be carried out.

In addition, in a case where rotation is slow, rotation is detected in a section (b region) in which the speed of the rotor 202 becomes the maximum after blocking the main drive pulse P 1 , and thus a stable induced current Ik with a high level (in other words, an induced voltage signal VRs) may be obtained, and thus it is not likely to be affected by the load variation. Accordingly, stable detection performance may be provided.

In addition, the rotation detection immediately after blocking the main drive pulse P 1 is carried out, and thus it is not likely to be affected by the load variation, and improvement in accuracy of a drive control operation on the basis of time at which the induced voltage signal VRs is generated may be realized. Accordingly, there is an effect of reducing useless power consumption.

In addition, since rotation detection accuracy is improved, it is possible to reduce driving with the correction drive pulse P 2 due to false detection as non-rotation in spite of rotation, and thus waste of power consumption may be suppressed.

In addition, when the rotation state is detected using a phenomenon in which a rotation detection time is delayed along with an increase in a load, occurrence of a problem, in which an angular velocity of the rotor 202 decreases at a load variation (a calendar load, or a load of a moment of the long hand) over a certain degree, the induced voltage signal VRs decreases, and driving with the correction drive pulse P 2 is carried out although rotation continues, may be reduced. Accordingly, power consumption may be reduced, and lifespan of a battery that is used as a power source may be lengthened.

In addition, in the stepping motor control circuit using a phenomenon in which the detection time of the induced voltage signal VRs is delayed along with an increase in a load, it is not likely to be affected by a load variation, and thus stable detection becomes possible.

Next, a second embodiment of the invention will be described.

In the first embodiment, the rotation state is determined by detecting the induced signal VRs of one polarity, and a direction of the induced current Ik is selected on the basis of the determination result to carry out rotation detection. However, in the second embodiment of the invention, the rotation state is determined by detecting an induced signal VRs of each of both polarities, and the direction of the induced current Ik is selected on the basis of the determination result to carry out rotation detection. According to this, even when drive energy with respect to a load is relatively decreased, rotation detection in the region b not the region c is reliably carried out by selecting an appropriate induced current Ik, whereby accurate rotation detection may be realized. In addition, in the first embodiment, two kinds of reference voltages Vinv and Vcomp are used as a reference voltage, but in the second embodiment, one kind of reference threshold voltage Vcomp is used as a reference voltage.

FIG. 9 shows a timing chart of a case where the stepping motor 107 is driven with the main drive pulse P 1 in the second embodiment of the invention.

FIG. 9 illustrates a state during normal driving (during a hand movement operation of time indicating hands 114 to 116 by the main drive pulse P 1 in a state in which a power supply voltage of the analog electronic timepiece is a rated voltage). In addition, in FIG. 9 , P 1 represents the main drive pulse P 1 , and a drive section in which the rotor 202 is rotatably driven by the main drive pulse P 1 . In addition, a to e are regions indicating rotation positions of the magnetic axis A of the rotor 202 during driving with the main drive pulse P 1 .

A predetermined period after termination of driving with the main drive pulse P 1 is set as a detection section T in which a rotation state is detected, and the detection section T is divided into a plurality of continuous sections. In a case of detecting an induced current Ik flowing in the same direction as the drive current flowing through the drive coil 209 during driving with the main drive pulse P 1 , two sections including a first section T 1 b and a fourth section T 2 are used. In addition, in a case of detecting an induced current Ik flowing in a direction opposite to that of the drive current flowing through the drive coil 209 during driving with the main drive pulse P 1 , three sections including the first section T 1 b , a second section T 2 R, and a third section T 3 R are used. The sum of a time width of the section T 2 R and a time width of the section T 3 R is equal to a time width of the section T 2 . In addition, the section T 1 a is a mask section provided immediately after the driving with the main drive pulse, and the induced current Ik generated in the section T 1 a is not used for determination of a rotation state.

When the XY coordinate space centering around the rotor 202 , in which the magnetic pole axis A of the rotor 202 is located by the rotation of the rotor 202 , is divided into a first quadrant I to a fourth quadrant IV, the sections T 1 b , T 2 , T 2 R, and T 3 R may be expressed as follows.

For example, in a large-load-increment driving (small-margin rotation) state in which the rank of the main drive pulse P 1 is retained without being changed, in a case of detecting the induced current Ik flowing in a direction (different direction) opposite to that of the drive current i, the section T 2 R is a section in which the rotation state of the rotor 202 in a first forward region b in the third quadrant III is determined, and the section T 3 R is a section in which the rotation state of the rotor 202 in a first backward region c in the third quadrant III is determined.

In a large-margin rotation state in which the main drive pulse P 1 is pulsed down, in a case of detecting the induced current Ik flowing in the same direction (one direction) as the drive current i, the section T 1 b is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III is determined, and the section T 2 is a section in which the rotation state of the rotor 202 after the first backward region c in the third quadrant III is determined.

›DETAILED DESCRIPTION OF THE INVENTION · 16 of 28

As the reference voltage that detects the induced voltage signal VRs, one kind of reference voltage Vcomp is used.

In the section T 1 b , both an induced voltage signal VRs which corresponds to an induced current Ik flowing through the drive coil 209 in the same direction as the drive current i, and an induced voltage signal VRs which corresponds to an induced current Ik flowing through the drive coil 209 in a direction opposite to that of the drive current i are detected.

When a load with respect to energy of the main drive pulse P 1 increases, rotation of the rotor 202 becomes slow, and thus a time at which the induced current Ik is generated is delayed. In this case, the induced current Ik which is generated before the section T 1 b is delayed, and is detected in the section T 1 b.

That is, in a case where the load with respect to the energy of the main drive pulse P 1 is smaller than a predetermined value, the rotor 202 rotates at a speed higher than a constant speed in the section T 1 b , and thus an induced current Ik which flows in the same direction as the drive current i and exceeds a predetermined value is not detected, and an induced current Ik which flows in a direction opposite to the direction of the drive current i and exceeds a predetermined value is detected.

Conversely, in a case where the load with respect to the energy of the main drive pulse P 1 is larger than a predetermined value, the rotation speed of the rotor 202 is slower than a constant speed in the section T 1 b , and thus the induced current Ik which flows in the same direction as the drive current i and exceeds a predetermined value is detected, and the induced current Ik which flows in a direction opposite to that of the drive current i and exceeds a predetermined value is not detected.

The second embodiment utilizes the phenomenon as described above, and is configured in such a manner that the detection is carried out by selecting a direction of the induced current Ik to be detected in subsequent sections on the basis of whether or not the induced voltage signal VRs exceeding a predetermined reference voltage is detected in the section T 1 b of each polarity, and determination of the rotation state or pulse control is carried out.

As described above, detection is carried out by changing polarity (detection direction) for detecting the induced current Ik in the sections T 2 , T 2 R, and T 3 R after the section T 1 b on the basis of whether or not the induced current Ik exceeding a predetermined reference value is detected in the first section T 1 b of both polarities, the rotation state of the stepping motor 107 is detected on the basis of the induced current Ik in each of the sections T 1 b , T 2 , T 2 R, and T 3 R (actually, an induced voltage signal VRs equivalent to the induced current Ik). Accordingly, even when a load is large and the rotation of the rotor 202 is slow, rotation detection may be carried out at a stage in which the rotation of the rotor 202 is fast, and thus accurate rotation detection may be carried out by reducing an effect due to a load variation.

In addition, in a case where the rotor 202 is rotated at a speed higher than a constant speed at which the induced current Ik exceeding a predetermined reference value may not be detected at one polarity in the first section T 1 b , a sufficiently large induced voltage signal VRs may be detected even when the direction of the induced current Ik is not changed. Accordingly, a detection process is configured to be simple by carrying out the rotation detection on the basis of the induced voltage signal VRs corresponding to the induced current Ik that flows in the same direction as the main drive pulse P 1 without changing the direction of the induced current Ik.

As described above, in the section T 1 b , the induced current Ik exceeding a reference value is detected at both polarities, and a detection target in subsequent sections is changed, thereby increasing rotation detection accuracy.

FIG. 10 shows a determination chart in which pulse control operations in the second embodiment of the invention are arranged.

The sections T 1 b and T 2 are sections in which detection is carried out when the drive current i and the induced current Ik flow in the same direction, and the sections T 2 R, T 3 R, and T 2 are sections in which the induced current Ik is detected by setting the detection direction to a direction opposite to that of the section T 2 . A width of the section T 2 is equal to the sum of a width of the section T 2 R and a width of the section T 3 R.

As described above, a case in which the induced voltage signal VRs exceeding the reference voltage Vcomp is detected is expressed by a determination value “1”, and a case in which the induced voltage signal VRs exceeding the reference voltage Vcomp is not detected is expressed by a determination value “0”, respectively. In addition, “1/0” represents that the determination value may be either “1” or “0”. In addition, “-” represents that the determination value is not considered as a pattern of the induced voltage signal VRs.

The rotation detection circuit 108 detects whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is present, the detection section determination circuit 109 determines the pattern (representing the degree of margin of the energy of the main drive pulse P 1 ) of the induced voltage signal VRs, and the control circuit 103 carries out the following pulse control such as pulse-up or pulse-down of the main drive pulse P 1 , and driving with the correction drive pulse P 2 on the basis of the pattern with reference to the determination chart of FIG. 10 which is stored inside the control circuit 103 , thereby rotatably controlling the stepping motor 107 .

FIG. 11 shows a partially detailed circuit diagram used in the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention. FIG. 5 shows a partially detailed circuit diagram of the motor driver circuit 106 and the rotation detection circuit 108 . The same reference numerals are given to the same parts as FIG. 5 .

›DETAILED DESCRIPTION OF THE INVENTION · 17 of 28

A comparator 310 that detects the induced signal VRs generated in a detection resistor 301 , and a comparator 311 that detects the induced signal VRs generated in a detection resistor 302 are provided. The comparators 310 and 311 are constituent elements of the rotation detection circuit 108 .

As a reference voltage of the comparators 310 and 311 , the same reference threshold voltage Vcomp is input. In a case where the induced voltage signal VRs detected by each of the corresponding detection resistors 301 and 302 exceeds the reference threshold voltage Vcomp, each of the comparators 310 and 311 outputs a determination value “1” as a detection signal, and in a case where the induced voltage signal VRs does not exceed the reference threshold voltage Vcomp, each of the comparators 310 and 311 outputs a determination value “0” as a detection signal Vs. The detection section determination circuit 109 selects the output of each of the comparators 310 and 311 , each corresponding to a direction of the induced current Ik that is detected, and outputs a determination value of each section.

FIG. 12 shows a timing chart according to the second embodiment of the invention in a case where detection is carried out without changing a detection direction of the induced current Ik. FIG. 12 shows a timing chart of the small-load-increment driving (large-margin rotation) state, and illustrates a timing during detection in a state in which the induced current Ik flows in the same direction as the drive current i. In this case, the rotation state is determined according to a pattern of the determination value of the induced signal VRs in the first section T 1 b and the fourth section T 2 .

In a case where the stepping motor 107 is rotatably driven, in a drive period P 1 between times ta and tb, the switch control circuit 303 repetitively switches the transistor Q 2 between an ON-state (supply state) and an OFF-state (supply stop state) at a predetermined cycle while maintaining the transistor Q 3 in an ON-state to generate a comb-like main drive pulse P 1 , and supplies the drive current i in an arrow direction of FIG. 11 to the drive coil 209 of the stepping motor 107 . According to this, in a case where the stepping motor 107 rotates, the rotor 202 rotates in a forward direction by 180°.

On the other hand, detection of a rotation state is carried out in a detection section T from the termination time tb of the drive period P 1 of the main drive pulse P 1 to time tc.

With regard to the detection of the rotation state, first, in the section T 1 starting from the time tb (a section in which the mask section T 1 a is added to the section T 1 b ), the switch control circuit 303 detects the induced signal VRs of both polarities. In this case, the switch control circuit 303 controls respective transistors Q 1 to Q 6 in such a manner that a first detection state (1) and a second detection state (2) to be described below are alternately repeated while maintaining transistors Q 1 and Q 2 in an OFF-state. The first detection state (1) is a detection state in which detection is carried out by switching the transistor Q 4 between an ON-state and an OFF-state at a predetermined cycle to allow the induced current Ik to flow through the detection resistor 302 in the same direction as the drive current i at a predetermined cycle while maintaining the transistors Q 3 and Q 6 in an ON-state. The second detection state (2) is a detection state in which detection is carried out by switching the transistor Q 3 between an ON-state and an OFF-state to allow the induced current Ik to flow through the detection resistor 301 in a direction opposite to that of the drive current i while maintaining the transistors Q 4 and Q 5 in an ON-state.

According to this, in the first detection state, the induced voltage signal VRs is generated in the detection resistor 302 , and in the second detection state, the induced voltage signal VRs is generated in the detection resistor 301 .

The comparator 311 compares the induced voltage signal VRs generated in the detection resistor 302 and the reference voltage Vcomp. When the induced voltage signal VRs exceeds the reference voltage Vcomp, the comparator 311 outputs “1” to the detection section determination circuit 109 as the detection signal Vs, and when the induced voltage signal VRs does not exceed the reference voltage Vcomp, the comparator 311 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

In addition, the comparator 311 compares the induced voltage signal VRs generated in the detection resistor 301 and the reference voltage Vcomp. When the induced voltage signal VRs exceeds the reference voltage Vcomp, the comparator 311 outputs “1” to the detection section determination circuit 109 as the detection signal Vs, and when the induced voltage signal VRs does not exceed the reference voltage Vcomp, the comparator 311 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

The detection section determination circuit 109 ignores the induced voltage signal VRs in the mask section T 1 a and does not carry out the determination of this signal VRs, and carries out the determination of the induced voltage signal VRs in the section T 1 b.

Since a determination value in an OUT 1 of one polarity is “0”, and a determination value in an OUT 2 of the other polarity is “1”, in a subsequent section, the detection section determination circuit 109 detects the induced current Ik flowing in the same direction as the drive current i. That is, the detection section determination circuit 109 determines whether or not the induced voltage signal VRs exceeding the reference threshold voltage Vcomp is detected in the section T 2 .

In this case, the detection signal Vs is input to the detection section determination circuit 109 from both of the comparators 310 and 311 . However, in the section T 2 , the detection section determination circuit 109 carries out determination with respect to only the detection signal Vs transmitted from the comparator 311 whether or not the detection signal Vs belongs to the section T 2 . According to this, determination of the rotation state may be carried out more accurately. In addition, since the detection direction of the induced current Ik is not changed, the detection operation becomes simple.

›DETAILED DESCRIPTION OF THE INVENTION · 18 of 28

As a determination result, the detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 b and a determination value in the section T 2 ) of the induced voltage signal VRs to the control circuit 103 .

The control circuit 103 determines the rotation state of the stepping motor 107 with reference to the determination chart of FIG. 10 on the basis of the pattern output from the detection section determination circuit 109 , and carries out pulse control such as pulse-down, and pulse-up+driving with the correction drive pulse P 2 .

Even in a next cycle after termination of the cycle shown in FIG. 12 , polarity of the induced voltage signal VRs to be detected in a section after the section T 1 is determined in the section T 1 b on the basis of the induced voltage signal VRs of both polarities, and a rotation detection operation is carried out.

FIG. 13 shows a timing chart of the second embodiment of the invention in a case where detection is carried out by changing the detection direction of the induced current Ik. FIG. 13 illustrates a timing in a large-load-increment driving (small-margin rotation) state. In FIG. 13 , to carry out detection by changing the detection direction of the induced current Ik to an opposite direction in the sections T 2 R and T 3 R, detection is carried out by inverting the polarity of the induced voltage signal VRs. According to this, the detection of the induced voltage signal VRs is configured to be carried out in the region b earlier in time instead of the region c later in time as shown in FIG. 12 so as to carry out the rotation detection with relatively high accuracy even when rotation is slow.

That is, in FIG. 13 , similarly to FIG. 12 , the stepping motor 107 is rotatably driven between times ta and tb, and in a section T 1 (section T 1 a +section T 1 b ) starting from the time tb, the induced signal VRs of both polarities is detected.

Since a determination value in the OUT 1 of one polarity is “1”, and a determination value in the OUT 2 of the other polarity is “0”, in a subsequent section, the detection section determination circuit 109 detects the induced current Ik flowing in a direction opposite to that of the drive current i. That is, the detection section determination circuit 109 determines whether or not the induced voltage signal VRs exceeding the reference threshold voltage Vcomp is detected in the sections T 2 R and T 3 R.

In this case, the detection signal Vs is input to the detection section determination circuit 109 from both of the comparators 310 and 311 . However, in the sections T 2 R and T 3 R, the detection section determination circuit 109 carries out determination with respect to only the detection signal Vs transmitted from the comparator 310 whether or not the detection signal Vs belongs to the section T 2 R or the section T 3 R. According to this, the rotation state is detected early, and thus determination of the rotation state may be carried out more accurately.

As a determination result, the detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 b , a determination value in the section T 2 R, and a determination value in the section T 3 R) of the induced voltage signal VRs to the control circuit 103 .

In FIG. 13 , the switch control circuit 303 operates so that the detection is carried out by changing the detection direction of the induced current Ik to an opposite direction in sections (the third section T 2 R and the fourth section T 3 R) that are continuous with the section T 1 b . The sum of a time width of the section T 2 R and a time width of the section T 3 R is configured to be equal to the time width of the section T 2 .

In the sections T 2 R and T 3 R, the switch control circuit 303 switches the transistor Q 3 between an ON-state and an OFF-state at a predetermined cycle while maintaining the transistors Q 4 and Q 5 in an ON-state and the transistor Q 6 in an OFF-state so as to allow the induced current Ik to flow through the detection resistor 301 . In the detection resistor 301 , the induced voltage signal VRs in which the detection direction is opposite to that of the sections T 1 b is generated, and thus detection of the induced current Ik in which the detection direction is changed to the opposite direction is carried out. According to this, the detection of the induced voltage signal VRs generated in the region b is carried out.

The comparator 310 compares the induced voltage signal VRs and the reference voltage Vcomp. In a case where the induced voltage signal VRs exceeds the reference voltage Vcomp, the comparator 310 outputs “1” to the detection section determination circuit 109 as a detection signal Vs, and in a case where the induced voltage signal VRs does not exceed the reference voltage Vcomp, the comparator 310 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

In addition, the comparator 311 compares the induced voltage signal VRs and the reference voltage Vcomp. In a case where the induced voltage signal VRs exceeds the reference voltage Vcomp, the comparator 310 outputs “1” to the detection section determination circuit 109 as the detection signal Vs, and in a case where the induced voltage signal VRs does not exceed the reference voltage Vcomp, the comparator 310 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

›DETAILED DESCRIPTION OF THE INVENTION · 19 of 28

As described above, in a case where it is determined that energy of the main drive pulse P 1 with respect to a load is small and rotation of the rotor 202 is slow in section T 1 b on the basis of induced currents Ik from the OUT 1 and OUT 2 , each having different polarity, since in sections after the section T 1 , detection is carried out by changing the detection direction of the induced current Ik to an opposite direction, and determination of the rotation state is carried out, the rotation detection is possible at a stage (the rotation region b of the rotor 202 ) in which rotation of the rotor is fast. Accordingly, the rotation state may be detected more accurately.

Even in a next cycle after termination of the cycle shown in FIG. 13 , the respective transistors Q 1 to Q 6 are drive-controlled so that polarity of the induced voltage signal VRs to be detected in a section after the section T 1 is determined in the section T 1 b on the basis of the induced voltage signal VRs of both polarities, and a rotation detection operation is carried out.

FIG. 14 shows a flowchart illustrating the operation of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the second embodiment of the invention. The flowchart mainly illustrates a process of the control circuit 103 . The same reference numerals are given to portions in which a process of the same content as FIG. 8 is carried out.

Hereinafter, an operation of the second embodiment of the invention will be described in detail with reference to FIGS. 1 , 2 , and 9 to 14 .

The control circuit 103 carries out a time counting operation by counting the timepiece signal transmitted from the frequency dividing circuit 102 , and first of all, resets an energy rank n of the main drive pulse P 1 n , and a counted value N indicating the number of times of continuous driving with the same main drive pulse P 1 to 0 (step S 501 in FIG. 14 ).

The control circuit 103 carries out initial setting to allow the rotation detection circuit 108 to carry out rotation detection on the basis of the induced current Ik (in other words, the induced voltage signal VRs) flowing in the same direction as the drive current i (setting to Rs-N) (step S 502 ).

The main drive pulse generation circuit 104 outputs the main drive pulse P 10 corresponding to the control signal to the motor driver circuit 106 in response to the control signal output from the control circuit 103 . The motor driver circuit 106 rotatably drives the stepping motor 107 with the main drive pulse P 10 . The stepping motor 107 is rotatably driven with main drive pulse P 10 , and rotatably drives the time indicating hands 114 to 116 of the analog display portion 112 . According to this, in a case where the stepping motor 107 is normally rotated, a current time is displayed at any time in the analog display portion 112 by the time indicating hands 114 to 116 . In addition, in a case where a calendar display portion (not shown) is rotatably driven by the stepping motor 107 , calendar display is changed to display of the next day.

The rotation detection circuit 108 detects whether or not the induced current Ik that flows in the same direction as the drive current i and exceeds a predetermined reference value is present. In other words, the rotation detection circuit 108 determines whether or not the induced voltage signal VRs exceeding a predetermined reference voltage Vcomp is detected in the section T 1 b . That is, first, as described with reference to FIGS. 12 and 13 , the rotation detection circuit 108 detects the induced voltage signal VRs while allowing the induced current Ik to flow in the same direction as the drive current i. The control circuit 103 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vcomp (step S 505 ).

In process step S 505 , in a case where it is determined that the induced signal VRs exceeding the reference voltage Vcomp is not detected, in subsequent sections, as shown in FIG. 12 , the control circuit 103 controls the rotation detection circuit 108 to determine whether or not an induced voltage signal VRs exceeding the reference voltage Vcomp is detected while retaining the detection direction of the induced current Ik without change. The detection section determination circuit 109 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vcomp in the section T 2 .

The control circuit 103 determines whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 2 (step S 506 ). In a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is not detected in the section T 2 , the control circuit 103 carries out the process of process steps S 508 to S 511 , and returns to process step S 502 .

In process step S 506 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 2 , the control circuit 103 carries out the process of process step S 530 to S 534 , and returns to process step S 502 .

On the other hand, in process step S 505 , in a case where it is determined that the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vcomp, as described with reference to FIG. 13 , the control circuit 103 carries out control in order for the rotation detection circuit 108 to carry out rotation detection after changing the detection direction of the induced current Ik (in other words, induced voltage signal VRs) to the opposite direction (setting to Rs-R) (step S 522 ).

›DETAILED DESCRIPTION OF THE INVENTION · 20 of 28

As described with reference to FIG. 13 , in the sections T 2 R and T 3 R, the rotation detection circuit 108 detects whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is present after changing the detection direction of the induced current Ik to the opposite direction by changing the detection resistors 301 and 302 . The detection section determination circuit 109 determines whether or not the induced voltage signal VRs, which is detected by the rotation detection circuit 108 and exceeds the reference voltage Vcomp, belongs to the sections T 2 R or T 3 R, and outputs a pattern of the induced voltage signal VRs to the control circuit 103 .

That is, in a case where it is determined that the induced voltage signal VRs detected in the section T 1 b exceeds the reference voltage Vcomp, the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 2 R (step S 525 ).

In process step S 525 , when it is determined that another induced voltage signal VRs exceeding the reference voltage Vcomp is not detected in the section T 2 R, the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 3 R (step S 526 ).

In process step S 526 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is not detected in the section T 3 R, the control circuit 103 carries out the process of process steps S 508 to S 511 , and then returns to process step S 502 . In a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 3 R, the control circuit 103 carries out the process of process step S 509 to S 511 , and then returns to process step S 502 .

In process step S 525 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 2 R, the control circuit 103 transitions to process step S 531 .

As described above, the stepping motor control circuit according to the second embodiment of the invention includes; a rotation detection unit that detects an induced current flowing through a drive coil due to free vibration of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not an induced current exceeding a predetermined reference value is detected in each of the sections by using a phenomenon in which a detection time of the induced current is delayed along with a relative load increase with respect to drive energy, and a level of the induced current decreases; and a control unit that selects a drive pulse corresponding to the rotation state that is detected by the rotation detection unit among a plurality of kinds of drive pulses, each having different energy, and supplies a drive current to the drive coil by the selected drive pulse to rotatably drive the stepping motor. The rotation detection unit includes first and second detection elements that detect induced currents flowing through the drive coil due to free vibration of the stepping motor in directions opposite to each other, and is configured to detect the induced current in the detection section by alternately repeating a first closed circuit including the drive coil of the stepping motor and the detection elements, and a second closed circuit constituted by the drive coil and a low-impedance element. In a first section T 1 b that is an initial section of the detection section, the rotation detection unit carries out the detection by selecting a detection element to be used in sections after the first section on the basis of detection results of the induced current using the first and second detection elements, and detects the rotation state of the stepping motor by a pattern based on the induced current detected in each of the sections.

Here, the detection section is divided into the first section T 1 b after driving with the drive pulse, a second section T 2 R after the first section T 1 b , and a third section T 3 R after the second section T 2 R, and in a state in which the stepping motor 107 is driven while retaining a rank of the main drive pulse P 1 , the first section T 1 b is a section in which a first forward rotation state of the rotor 202 in a second quadrant II of a space centering around the rotor 202 of the stepping motor 107 is determined, the second section T 2 R is a section in which a first forward rotation state of the rotor 202 in a third quadrant III is determined, and the third section T 3 R is a section in which a first backward rotation state of the rotor 202 in the third quadrant III is determined. The rotation detection unit may be configured as follows. In a case where an induced current Ik, which exceeds a predetermined value, in a direction opposite to the direction of the drive current i is detected, the rotation detection unit carries out the detection of an induced current Ik in the same direction as the drive current i after the second section T 2 R, and carries out determination of a rotation state.

In addition, the rotation detection unit may be configured as follows. In a case where an induced current Ik, which exceeds a predetermined value, in a direction opposite to the direction of the drive current i is detected, the rotation detection unit carries out the detection of the induced current Ik in a fourth section T 2 obtained by unifying the second section T 2 R and the third section T 3 R, and carries out determination of the rotation state on the basis of a pattern of induced currents Ik detected in the first section T 1 b and the fourth section T 2 .

In addition, the detection section T is divided into the first section T 1 b after driving with the drive pulse, a second section T 2 R after the first section T 1 b , and a third section T 3 R after the second section T 2 R, and in a state in which the stepping motor is driven while retaining a rank of the drive pulse, the first section T 1 b is a section in which a first forward rotation state of the rotor 202 in a second quadrant II of a space centering around the rotor 202 of the stepping motor 107 is determined, the second section T 2 R is a section in which a first forward rotation state of the rotor 202 in a third quadrant III is determined, and the third section T 3 R is a section in which a first backward rotation state of the rotor 202 in the third quadrant III is determined. The rotation detection unit may be configured as follows. In a case where an induced current Ik, which exceeds a predetermined value, in the same direction as the drive current i is detected, the rotation detection unit carries out the detection of an induced current Ik in a direction opposite to the direction of the drive current i after the second section T 2 R to determine a rotation state.

›DETAILED DESCRIPTION OF THE INVENTION · 21 of 28

In addition, the rotation detection unit may be configured as follows. In a case where an induced current Ik, which exceeds a predetermined value, in the same direction as the drive current i is detected, the rotation detection unit carries out determination of the rotation state on the basis of a pattern of induced currents Ik detected in the first to third sections T 1 b to T 3 R.

As described above, in the second embodiment of the invention, an appropriate direction of a rotation detection current is selected using the induced signals VRs from the OUT 1 and OUT 2 , each having different polarity, in the section T 1 b to reduce a variation in drive remaining power (magnitude of a load with respect to drive energy), thereby realizing rotation determination with high accuracy.

Accordingly, the same effect as the first embodiment may be obtained. In addition, since detection is carried out in the region b at which the speed of the rotor becomes the maximum after blocking the drive pulse P 1 , a stable induced signal VRs may be obtained in a level higher than the case of carrying out detection in the region c, and it is not likely to be affected by the load variation. Accordingly, stable detection performance may be obtained.

In addition, the rotation detection immediately after blocking the drive pulse P 1 is carried out, and thus it is not likely to be affected by the load variation, and it is possible to realize improvement in accuracy of a control operation of determining a drive margin on the basis of time at which the induced signal VRs exceeding a predetermined level is generated. Accordingly, there is an effect of reducing useless power consumption.

Next, a third embodiment of the invention will be described.

In the first embodiment of the invention, the rotation state is determined by detecting the induced signal VRs of one polarity in the first section T 1 with a fixed time width, and the direction of the induced current Ik is selected on the basis of the determination result to carry out rotation detection. However, in the third embodiment of the invention, the rotation state is determined by detecting the induced signal VRs of one polarity in the first section with a variable time width, and the direction of the induced current Ik is selected on the basis of the determination result to carry out the rotation detection. In addition, similarly to the first embodiment, as the reference voltage, two kinds of reference voltages Vinv and Vcomp are used.

According to this, even when drive energy with respect to a load is relatively decreased, rotation detection in the region b not the region c is reliably carried out by accurately grasping a rotation state, whereby accurate rotation detection may be realized.

FIG. 15 shows a timing chart in a case of driving the stepping motor 107 with the main drive pulse P 1 in the third embodiment of the invention. FIG. 15 illustrates a state during normal driving (during a hand movement operation of time indicating hands 114 to 116 by the main drive pulse P 1 in a state in which a power supply voltage of the analog electronic timepiece is a rated voltage).

A predetermined period after termination of driving with the main drive pulse P 1 is set as a detection section T in which a rotation state is detected, and the detection section T is divided into a plurality of continuous sections. In a case of detecting an induced current Ik flowing in the same direction as the drive current i flowing through the drive coil 209 during driving with the main drive pulse P 1 , three sections including a fifth section T 1 a , a sixth section T 1 b , and a fourth section T 2 are used. In addition, in a case of detecting an induced current Ik flowing in a direction opposite to that of the drive current i flowing through the drive coil 209 during driving with the main drive pulse P 1 , four sections including the fifth section T 1 a , the sixth section T 1 b , and a second section T 2 R, and a third section T 3 R are used.

The time width of the section T 1 a is fixed to a constant value. The time width of the section T 1 b varies in response to the induced signal VRs that is detected, but the longest time width is set to a predetermined value. The time width of the section T 3 R is fixed to a predetermined width. In addition, the sum of the time width of the section T 1 b , the time width of the section T 2 R, and the time width of the third section T 3 R is configured to be equal to the time width of the section T 2 . The section T 1 a and the section T 1 b constitute the section T 1 . The time width of the detection section T is configured not to vary. In addition, in the third embodiment, the mask section is not provided.

When the XY coordinate space centering around the rotor 202 , in which the magnetic pole axis A of the rotor 202 is located by the rotation of the rotor 202 , is divided into a first quadrant I to a fourth quadrant IV, the sections T 1 , T 1 a , T 1 b , T 2 , T 2 R, and T 3 R may be expressed as follows.

For example, in a large-load-increment driving (small-margin rotation) state in which the rank of the main drive pulse P 1 is retained without being changed, the sections T 1 a and T 1 b are sections in which a rotation state of the rotor 202 in a first forward region a in the second quadrant II is determined, the section T 2 R is a section in which the rotation state of the rotor 202 in the first forward region a in the second quadrant II, and a rotation state of the rotor 202 in a first forward region b in the third quadrant III are determined, and the section T 3 R is a section in which the rotation state of the rotor 202 in a first forward region b in the third quadrant III, and a rotation state of the rotor 202 in a first backward region c in the third quadrant III are determined.

In addition, in a small-load-increment driving (represents maximum-margin rotation, and the section T 1 b is not used in the driving) in which the rank of the main drive pulse P 1 is pulsed down, the section T 1 a is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III is determined, and the section T 2 is a section in which the rotation state of the rotor 202 in the first forward region b in the third quadrant III, and a rotation state of the rotor 202 in a section after the first backward region c in the third quadrant III are determined.

›DETAILED DESCRIPTION OF THE INVENTION · 22 of 28

Similarly to the first embodiment, as the reference voltage for detecting the induced voltage signal VRs, two kinds of predetermined reference voltages Vinv and Vcomp are used. A case in which an induced voltage signal VRs exceeding a first reference voltage Vinv is detected is equivalent to a case in which the induced current Ik exceeding the first reference value is detected. In addition, a case in which an induced voltage signal VRs exceeding a second reference voltage Vcomp is detected is equivalent to a case in which an induced current Ik exceeding the second reference value is detected. The second reference value is larger than the first reference value, and the second reference voltage Vcomp is set to a value larger than that of the first reference voltage Vinv. The first reference voltage Vinv is a reference of determining a degree of margin of drive energy, and is a reference voltage at the time of carrying out rotation detection on the basis of an induced current Ik of polarity opposite to that of the drive current i. The second reference voltage Vcomp is a reference voltage at the time of carrying out the rotation detection on the basis of the induced current Ik of the same polarity as the drive current i.

In the sections T 1 a and T 1 b , rotation determination is carried out by the reference voltage Vinv, and the detection direction and the reference voltage are selected in response to the detection result to carry out rotation detection.

For example, in a case where a plurality of induced signals VRs do not exceed the reference voltage Vinv in the section T 1 a , an induced signal VRs corresponding to the induced current Ik in the same current direction as the drive current i of the main drive pulse P 1 is detected, and determination is carried out using high reference voltage Vcomp to reliably carry out the determination of non-rotation. That is, rotation detection in the section T 2 is carried out. In this case, in the example of FIG. 15 , it enters a maximum-margin rotation state, the main drive pulse P 1 is pulsed down.

In a case where a plurality of induced signals VRs exceeding the reference voltage Vinv are detected in the section T 1 a , detection continues until an induced signal VRs less than the reference voltage Vinv is generated. In a case where a plurality of induced signals VRs exceed the reference voltage Vinv in the section T 1 a , and then an induced signal VRs do not exceed the reference voltage Vinv in the section T 1 a , or in a case where an induced signal VRs does not exceed the reference voltage Vinv in the section T 1 b , at a point of time at which the section T 1 a is terminated or a point of time at which the induced signal VRs does not exceed the reference voltage Vinv, rotation detection is changed to rotation detection by the induced current Ik in a direction opposite to that of the drive current i of the main drive pulse P 1 , and rotation detection is carried out using the reference voltage Vinv. That is, rotation detection in the sections T 2 R and T 3 R is carried out. In this case, in the example of FIG. 15 , it enters an intermediate-margin rotation state, and the main drive pulse P 1 is pulsed down.

In the case where a plurality of induced signals VRs exceeding the reference voltage Vinv are detected in the section T 1 a , when an induced signals VRs exceeds the reference voltage Vinv in the entire region of the section T 1 a , and an induced signal VRs exceeds the reference voltage Vinv even in the section T 1 b , detection is carried out until an induced signal VRs less than the reference voltage Vinv is generated in the section T 1 b . In a case where the induced signal VRs less than the reference voltage Vinv is generated in the section T 1 b , at that point of time, rotation detection may be changed to rotation detection by the induced current Ik in a direction opposite to that of the drive current i of the main drive pulse P 1 by using the reference voltage Vinv. That is, rotation detection in the section T 2 R and the section T 3 R is carried out. In this case, in the example of FIG. 15 , it enters a small-margin rotation state, and the main drive pulse P 1 is retained.

In a case where a plurality of induced signals VRs exceeding the reference voltage Vinv are detected in the section T 1 a , when an induced signals VRs exceeds the reference voltage Vinv in the entire region of the section T 1 a , and an induced signal VRs exceeds the reference voltage Vinv in the entire region of the section T 1 b , at a point of time at which the maximum width of the section T 1 b is terminated, rotation detection may be changed to rotation detection by the induced current Ik in a direction opposite to that of the drive current i of the main drive pulse P 1 by using the voltage Vinv. That is, rotation detection in the section T 2 R and the section T 3 R is carried out. In this case, in the example of FIG. 15 , it enters a small-margin rotation state, and the main drive pulse P 1 is pulsed up. In addition, the maximum width of the section T 1 b is set to a predetermined width as a seventh section. In addition, the maximum length of the sum of the time width of the section T 1 a and the time width of the section T 1 b is set to be ½ or less times the detection section T.

FIG. 16 shows a determination chart in which pulse control operations in the third embodiment of the invention are arranged.

The sections T 1 a , T 1 b , and T 2 are sections in which detection is carried out when the drive current i and the induced current Ik flow in the same direction, and the section T 2 R and T 3 R are sections in which the induced current Ik is detected by setting the detection direction to a direction opposite to that of the section T 2 .

The rotation detection circuit 108 detects whether or not the induced voltage signal VRs exceeding the reference voltage Vcomp is present, and the detection section determination circuit 109 determines the pattern (representing the degree of margin of the energy of the main drive pulse P 1 ) of the induced voltage signal VRs, and the control circuit 103 carries out the following pulse control such as pulse-up or pulse-down of the main drive pulse P 1 , and driving with the correction drive pulse P 2 on the basis of the pattern with reference to the determination chart of FIG. 16 which is stored inside the control circuit 103 , thereby rotatably controlling the stepping motor 107 .

›DETAILED DESCRIPTION OF THE INVENTION · 23 of 28

FIG. 17 shows a timing chart of the third embodiment of the invention in a case where detection is carried out without changing the detection direction of the induced current Ik. FIG. 17 shows a timing chart in a small-load-increment driving (maximum-margin rotation) state, and illustrates a timing when detection is carried out in a state in which the induced current Ik flows in the same direction as the drive current i. In this case, the rotation state is determined by a pattern of a determination value of the induced signal VRs in the section T 1 a and the section T 2 .

In a case where the stepping motor 107 is rotatably driven, in a drive period P 1 between times ta and tb, the switch control circuit 303 repetitively switches the transistor Q 2 between an ON-state (supply state) and an OFF-state (supply stop state) at a predetermined cycle while maintaining the transistor Q 3 in an ON-state to generate a comb-like main drive pulse P 1 , and supplies the drive current i in an arrow direction of FIG. 5 to the drive coil 209 of the stepping motor 107 . According to this, in a case where the stepping motor 107 rotates, the rotor 202 rotates in a forward direction by 180°.

On the other hand, detection of a rotation state is carried out in a detection section T from the termination time tb of the drive period P 1 of the main drive pulse P 1 to time tc.

That is, in the section T 1 a starting from the time tb, the switch control circuit 303 switches the transistor Q 4 between an ON-state and an OFF-state at a predetermined cycle while maintaining the transistors Q 3 and Q 6 in an ON-state to allow the induced current Ik to flow to the detection resistor 302 in the same direction as the drive current i. According to this, the induced voltage signal VRs is generated in the detection resistor 302 .

The detection section determination circuit 109 determines whether or not a plurality of induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, at least two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 a on the basis of detection signals Vs transmitted from the comparator 304 and the NAND circuit 307 .

In an example of FIG. 17 , since a plurality of the induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 a , the switch control circuit 303 of the rotation detection circuit 108 carries out a detection operation without changing a flow direction of the induced current Ik even in the section T 2 . Accordingly, even in the section T 2 , each transistor is drive-controlled to carry out the same operation as described above.

In this case, in the section T 2 , a determination value of the induced voltage signal VRs, which is obtained by carrying out determination using the second reference voltage Vcomp without using the first reference voltage Vinv, is only used. That is, although the detection signal Vs is input to the detection section determination circuit 109 from both of the NAND circuit 307 and the comparator 304 , in the section T 2 , the detection section determination circuit 109 carries out determination only on whether or not the detection signal Vs input from the comparator 304 belongs to the section T 2 . According to this, even in a non-rotation state in which a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 a , determination is carried out using the second reference voltage Vcomp with a high level, and thus there is no concern of false determination between the non-rotation and rotation, and determination of the rotation state may be carried out more accurately. In addition, since the detection direction of the induced current Ik is not changed, the detection operation becomes simple.

As a determination result, the detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 a , a determination value in the section T 1 b , and a determination value in the section T 2 ) of the induced voltage signal VRs to the control circuit 103 .

The control circuit 103 determines the rotation state of the stepping motor 107 with reference to the determination chart of FIG. 16 on the basis of the pattern output from the detection section determination circuit 109 , and carries out pulse control such as pulse-up.

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 a even in a next cycle after the cycle shown in FIG. 17 is terminated, each of the transistors Q 1 to Q 6 is drive-controlled to carry out the same operation. That is, the transistor Q 4 enters an ON-state in place of the transistor Q 3 , and the transistor Q 1 is switched in place of the transistor Q 2 at the same cycle as the transistor Q 2 , and thus driving with a comb-like main drive pulse P 1 having polarity reversed to the previous cycle is carried out. In addition, in the detection section T, the transistor Q 3 is switched in place of the transistor Q 4 at the same cycle as the transistor Q 4 , and the transistors Q 4 and Q 5 are driven to an ON-state in place of the transistors Q 3 and Q 6 . According to this, rotation detection based on the induced current Ik is carried out.

›DETAILED DESCRIPTION OF THE INVENTION · 24 of 28

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 a , the same operation as described above is carried out, and in the section T 2 , similarly to the previous cycle, the detection section determination circuit 109 carries out section determination only with respect to the detection signal Vs transmitted from the comparator 304 .

The detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 a , a determination value in the section T 1 b , and a determination value in the section T 2 ) of the induced voltage signal VRs to the control circuit 103 .

In a case where a plurality of induced voltage signals VRs exceeding the predetermined reference voltage Vinv are not detected in the section T 1 a , rotation control of the stepping motor 107 is carried out by alternately repeating the above-described two cycles. In addition, in the case of non-rotation, driving with the correction drive pulse P 2 is carried out, but in this case, the rotation detection operation is not carried out.

FIG. 18 shows a timing chart of the third embodiment of the invention in a case where detection is carried out by changing the detection direction of the induced current Ik. FIG. 18 illustrates a timing in a large-load-increment driving (small-margin rotation) state. In FIG. 18 , to carry out detection by changing the detection direction of the induced current Ik to an opposite direction in the sections T 2 R and T 3 R, detection is carried out by inverting the polarity of the induced voltage signal VRs. According to this, the detection of the induced voltage signal VRs is configured to be carried out in the region b earlier in time instead of the region c later in time as shown in FIG. 17 so as to carry out the rotation detection with relatively high accuracy even when rotation is slow.

In a case where the stepping motor 107 is rotatably driven, in a drive period P 1 between times ta and tb, the switch control circuit 303 repetitively switches the transistor Q 2 between an ON-state (supply state) and an OFF-state (supply stop state) at a predetermined cycle while maintaining the transistor Q 3 in an ON-state to supply the drive current i in an arrow direction of FIG. 5 to the drive coil 209 of the stepping motor 107 with the comb-like main drive pulse P 1 . According to this, in a case where the stepping motor 107 rotates, the rotor 202 rotates in a forward direction by 180°.

On the other hand, detection of a rotation state is carried out in a detection section T from the termination time tb of the drive period P 1 of the main drive pulse P 1 to time tc.

The comparator 304 compares the induced voltage signal VRs and the second reference voltage Vcomp. When the induced voltage signal VRs exceeds the second reference voltage Vcomp, the comparator 304 outputs “1” to the detection section determination circuit 109 as the detection signal Vs. When the induced voltage signal VRs does not exceed the second reference voltage Vcomp, the comparator 304 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

The detection section determination circuit 109 determines whether or not a plurality of induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, at least two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 a on the basis of detection signals Vs transmitted from the comparator 304 and the NAND circuit 307 . That is, the detection section determination circuit 109 determines whether or not rotation of the rotor 202 is slower than a predetermined speed in the section T 1 a.

In an example of FIG. 18 , since a plurality of induced voltage signals VRs exceeding the first reference voltage Vinv is detected in the entire region of the section T 1 a (in a state in which the rotation of the rotor 202 is slow), even in the section T 1 b that is continuous with the section T 1 a , the switch control circuit 303 operates to detect the induced current Ik without changing the detection direction of the induced current Ik by using the first reference voltage Vinv. According to this, an induced signal exceeding the reference voltage Vinv is detected in the section T 1 b.

›DETAILED DESCRIPTION OF THE INVENTION · 25 of 28

In the section T 1 b , when the level of the induced signal VRs becomes equal to or less than the first reference voltage Vinv, from that point of time, in the section T 2 R and the section T 3 R, the switch control circuit 303 operates to carry out detection by changing the detection direction of the induced current Ik to a direction opposite to that of the section T 1 b . In this case, as the reference voltage, the first reference voltage Vinv is used to raise detection sensitivity so as to carry out accurate rotation detection even in a case where rotation is slow.

In the sections T 2 R and T 3 R, the switch control circuit 303 switches the transistor Q 3 between an ON-state and an OFF-state at a predetermined cycle while maintaining the transistors Q 4 and Q 5 in an ON-state and the transistor Q 6 in an OFF-state so as to allow the induced current Ik to flow through the detection resistor 301 . In the detection resistor 301 , the induced voltage signal VRs in which the detection direction is opposite to that of the sections T 2 and T 3 is generated, and thus detection of the induced current Ik in which the detection direction is changed to the opposite direction is carried out. According to this, the detection of the induced voltage signal VRs generated in the region b is carried out.

The comparator 304 compares the induced voltage signal VRs and the second reference voltage Vcomp. In a case where the induced voltage signal VRs exceeds the second reference voltage Vcomp, the comparator 304 outputs “1” to the detection section determination circuit 109 as a detection signal Vs, and in a case where the induced voltage signal VRs does not exceed the second reference voltage Vcomp, the comparator 304 outputs “0” to the detection section determination circuit 109 as the detection signal Vs.

In addition, in a case where the induced voltage signal VRs exceeds the first reference voltage Vinv, the inverter 306 outputs “0”, and in a case where the induced voltage signal VRs does not exceed the first reference voltage Vinv, the inverter 306 outputs “1”. The NAND circuit 307 outputs an inverted signal “1” or “0” to the detection section determination circuit 109 as the detection signal Vs.

In the sections T 2 R and T 3 R, rotation is slow and the level of the induced signal VRs is low, and thus a determination value of the induced voltage signal VRs, which is obtained by carrying out determination using the first reference voltage Vinv without using the second reference voltage Vcomp is only used so as to increase detection sensitivity. That is, although the detection signal Vs is input to the detection section determination circuit 109 from both of the NAND circuit 307 and the comparator 304 , in the sections T 2 R and T 3 R, the detection section determination circuit 109 carries out determination only on whether or not the detection signal Vs input from the NAND circuit 307 belongs to the section T 2 R or T 3 R.

As a determination result, the detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 a , a determination value in the section T 1 b , a determination value in the section T 2 R, and a determination value in the section T 3 R) of the induced voltage signal VRs to the control circuit 103 .

As described above, in a case where it is determined that the energy of the main drive pulse P 1 with respect to a load is small, and the rotation of the rotor 202 is slow in the section T 1 a (also including the section T 1 b in a case of using the section T 1 b ), in sections after the section T 1 a , detection is carried out after changing the detection direction of the induced current Ik to an opposite direction, and determination of the rotation state is carried out, whereby rotation detection in a stage in which the rotation of the rotor is fast (the rotation region b of the rotor 202 ) is possible, and thus the rotation state may be detected in a relatively accurate manner. In addition, even in a case where the rotation of the rotor 202 is slow, and the level of the induced voltage signal VRs is low, since a plurality of the induced voltage signals VRs exceeding a predetermined reference voltage (in this embodiment, two induced voltage signals VRs exceeding the first reference voltage Vinv) are detected in the section T 1 a , stable stopping at a position perpendicular to a line segment connecting the notched portions 204 and 205 is possible in a reliable manner, and the first reference voltage Vinv that is a relatively low reference voltage is used, and thus determination of the rotation state may be carried out in a relatively accurate manner.

In a case where a plurality of induced voltage signals VRs exceeding a plurality of predetermined reference voltages Vinv and Vcomp are detected in the section T 1 a even in a next cycle after the cycle shown in FIG. 18 is terminated, each of the transistors Q 1 to Q 6 is drive-controlled to carry out the same operation as described above. That is, the transistor Q 4 enters an ON-state in place of the transistor Q 3 , and the transistor Q 1 is switched in place of the transistor Q 2 at the same cycle as the transistor Q 2 , and thus driving with a comb-like main drive pulse P 1 having polarity reversed to the previous cycle is carried out.

In the section T 1 a of the detection section T, the transistor Q 3 is switched in place of the transistor Q 4 at the same cycle as the transistor Q 4 , and the transistors Q 4 and Q 5 are driven to an ON-state in place of the transistors Q 3 and Q 6 . According to this, the induced current Ik flows to the detection resistor 301 in the same direction as the drive current i, and thus the induced voltage signal VRs is generated in the detection resistor 301 . According to this, rotation detection based on the induced current Ik flowing in the same direction as the drive current i is carried out.

›DETAILED DESCRIPTION OF THE INVENTION · 26 of 28

In addition, in the sections T 2 R and T 3 R, the transistor Q 4 is switched between an ON-state and an OFF-state in place of the transistor Q 3 at a predetermined cycle while maintaining the transistors Q 3 and Q 6 in an ON-state in place of the transistors Q 4 and Q 5 , the induced current Ik is allowed to flow to the detection resistor 302 . The induced voltage signal VRs is generated in the detection resistor 302 . According to this, detection of the induced current Ik in which the detection direction is changed to an opposite direction is carried out.

Similarly to the previous cycle, with regard to the induced voltage signal VRs generated due to rotation of the stepping motor 107 , in the section T 1 a , a determination value may be obtained on the basis of the first reference voltage Vinv, and in the sections T 2 R and T 3 R, the determination value may be obtained only on the basis of the first reference voltage Vinv.

As a determination result, the detection section determination circuit 109 outputs a pattern (a determination value in the section T 1 a , a determination value in the section T 1 b , a determination value in the section T 2 , and a determination value in the section T 3 ) of the induced voltage signal VRs to the control circuit 103 .

FIG. 19 shows a flowchart illustrating the operation of the stepping motor control circuit, the movement, and the analog electronic timepiece according to the third embodiment of the invention. The flowchart mainly illustrates a process of the control circuit 103 . The same reference numerals are given to portions in which a process of the same content as FIG. 8 is carried out.

Hereinafter, an operation of the third embodiment of the invention will be described in detail with reference to FIGS. 1 , 2 , 5 , and 15 to 19 .

The control circuit 103 carries out initial setting to allow the rotation detection circuit 108 to carry out rotation detection on the basis of the induced current Ik (in other words, the induced voltage signal VRs) flowing in the same direction as the drive current i (setting to Rs-N) (step S 502 ).

The rotation detection circuit 108 detects whether or not the induced current Ik that flows in the same direction as the drive current i and exceeds a predetermined reference value is present. In other words, the rotation detection circuit 108 determines whether or not a plurality of induced voltage signals VRs exceeding a predetermined reference voltage Vinv is detected in the section T 1 a . That is, first, as described with reference to FIGS. 17 and 18 , the rotation detection circuit 108 detects the induced voltage signal VRs while allowing the induced current Ik to flow in the same direction as the drive current i. The control circuit 103 determines whether or not the rotation detection circuit 108 detects the plurality of induced voltage signals VRs exceeding the reference voltage Vinv (step S 505 ).

In process step S 505 , in a case where it is determined that the plurality of induced signals VRs exceeding the reference voltage Vinv are not detected, in the subsequent section T 2 , as shown in FIG. 17 , the control circuit 103 controls the rotation detection circuit 108 to determine whether or not an induced voltage signal VRs exceeding the reference voltage Vcomp is detected while retaining the detection direction of the induced current Ik without change. In addition, the detection section determination circuit 109 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vcomp in the section T 2 .

In process step S 506 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vcomp is detected in the section T 2 , the control circuit 103 carries out the process of process steps S 530 to S 534 , and returns to process step S 502 .

On the other hand, in process step S 505 , in a case where it is determined that the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vinv, as described with reference to FIG. 18 , the control circuit 103 carries out control in order for the rotation detection circuit 108 to carryout rotation detection in the sections T 2 R and T 3 R after changing the detection direction of the induced current Ik (in other words, induced voltage signal VRs) to the opposite direction (setting to Rs-R) (step S 522 ).

In the section T 1 b , the rotation detection circuit 108 detects whether or not the induced current Ik flowing in the same direction as the drive current i is present, that is, whether or not the induced voltage signal VRs exceeding the reference voltage Vinv is present, and the detection section determination circuit 109 determines whether or not the induced voltage signal VRs, which is detected by the rotation detection circuit 108 and exceeds the reference voltage Vinv, is included in the section T 1 b.

›DETAILED DESCRIPTION OF THE INVENTION · 27 of 28

The control circuit 103 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vinv (step S 191 ).

In process step S 191 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is not detected in the section T 1 b (step S 191 ), the control circuit 103 determines whether or not the rotation detection circuit 108 detects the induced voltage signal VRs exceeding the reference voltage Vinv in the section T 2 R (step S 192 ).

In process step S 192 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is not detected by the rotation detection circuit 108 in the section T 2 R, the control circuit 103 transitions to process step S 530 .

In process step S 192 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is detected by the detection circuit 108 in the section T 2 R, the control circuit 103 transitions to process step S 531 .

In process step S 191 , in a case where it is determined that the induced voltage signal VRs, exceeding the reference voltage Vinv is detected in the section T 1 b , the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the reference voltage Vinv is detected in the section T 2 R (step S 193 ).

In process step S 193 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is detected in the section T 1 b , the control circuit 103 transitions to process step S 531 .

In process step S 193 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is not detected in the section T 1 b , in process step S 194 , the control circuit 103 determines whether or not the induced voltage signal VRs exceeding the reference voltage Vinv is detected in the section T 3 R (step S 194 ).

In process step S 194 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is not detected in the section T 3 R, the control circuit 103 transitions to the process step S 508 (step S 194 ).

In process step S 194 , in a case where it is determined that the induced voltage signal VRs exceeding the reference voltage Vinv is detected in the section T 3 R, the control circuit 103 transitions to the process step S 509 .

As described above, the stepping motor control circuit according to the third embodiment of the invention includes: a rotation detection unit that detects an induced current flowing through a drive coil due to free vibration of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not an induced current exceeding a predetermined reference value is detected in each of the sections by using a phenomenon in which a detection time of the induced current is delayed along with a relative load increase with respect to drive energy, and a level of the induced current decreases; and a control unit that selects a drive pulse corresponding to the rotation state that is detected by the rotation detection unit among a plurality of kinds of drive pulses, each having different energy, and supplies a drive current to the drive coil by the selected drive pulse to rotatably drive the stepping motor.

The rotation detection unit is configured to carry out the detection by selecting a detection direction of the induced current in sections after a first section on the basis of whether or not an induced current exceeding a predetermined reference value is detected in the first section that is an initial section of the detection section, and to detect the rotation state of the stepping motor by a pattern based on the induced current detected in each of the sections.

A fifth section T 1 a having a predetermined time width from the beginning of the first section T 1 is set in the first section T 1 .

The rotation detection unit carries out the detection by selecting a detection direction of an induced current Ik in sections after the fifth section T 1 a on the basis of whether or not an induced current Ik exceeding a predetermined reference value is detected plural times in the fifth section T 1 a , and detects the rotation state of the stepping motor 107 by a pattern based on induced currents Ik detected in the fifth section T 1 a and the sections after the fifth section T 1 a.

Here, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the reference value is not detected plural times in the fifth section T 1 a , the rotation detection unit detects the induced current Ik by setting the fifth section T 1 a as the first section T 1 , and setting the detection direction to the same direction as the first section T 1 in sections after the first section T 1 , and detects the rotation state of the stepping motor 107 by a pattern based on induced currents Ik detected in the first section T 1 and the sections after the first section T 1 .

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the predetermined reference value is detected plural times in the fifth section T 1 a , the rotation detection unit detects the induced current Ik by setting a section until an induced current Ik lower than the reference value is detected after termination of the fifth section T 1 a as a sixth section T 1 b , and setting a detection direction in sections after the sixth section T 1 b to a direction opposite to the direction of the fifth section T 1 a , and detects the rotation state of the stepping motor 107 by a pattern based on induced currents Ik detected in the fifth section T 1 a , the sixth section T 1 b , and other sections.

In addition, the rotation detection unit may be configured as follows. In a case where the induced current Ik exceeding the reference value is detected plural times in the fifth section T 1 a , when a seventh section (the maximum width of the section T 1 b ) until an induced current lower than the reference value is detected after termination of the fifth section T 1 a exceeds a predetermined time width, the rotation detection unit detects the induced current by setting a detection direction in sections after the seventh section to a direction opposite to the direction of the fifth section T 1 a , and detects the rotation state of the stepping motor 107 by a pattern based on induced currents Ik detected in the fifth section T 1 a , the seventh section, and other sections T 2 R and T 3 R.

›DETAILED DESCRIPTION OF THE INVENTION · 28 of 28

In addition, in a state in which the stepping motor 107 is driven while retaining a rank of a main drive pulse P 1 , it may be configured that the fifth section T 1 a and the seventh section become sections in which a first forward rotation state of the rotor 202 in a second quadrant II of a space centering around the rotor 202 of the stepping motor 107 is determined.

In addition, the rotation detection unit may be configured as follows. The rotation detection unit includes first and second detection resistors 301 and 302 that detect induced currents Ik flowing through the drive coil 209 due to free vibration of the stepping motor 107 in directions opposite to each other, and detects the induced current Ik in the detection section T by alternately repeating a first closed circuit including the drive coil 209 of the stepping motor 107 and the detection resistors 301 and 302 , and a second closed circuit constituted by the drive coil 209 and a low-impedance element. The rotation detection unit carries out the detection by changing the detection element constituting the first closed circuit to the first detection resistor 301 or the second detection resistor 302 in correspondence with the direction of the induced current Ik that is detected.

In the first embodiment, since the section T 1 in which whether or not to change the current direction of the induced current Ik that is detected is determined is set to have a constant time width, there is a concern that an appropriate change timing may not be obtained, and it may be falsely determined as non-rotation in spite of rotation. However, in the third embodiment, the detection section (T 1 a +T 1 b ) in which whether or not to change the current direction of the induced current Ik that is detected is determined varies in order for the position of the rotor 202 when the section T 2 R is initiated to be the horizontal magnetic pole axis X, accurate rotation detection may be carried out at an early time. In addition, since it transitions to rotation detection at an appropriate timing after determining the current direction of the induced current Ik, stable rotation detection may be carried out. In addition, false rotation determination may be avoided, and useless power consumption may be suppressed.

In addition, the movement according to each embodiment of the invention is provided with the stepping motor control circuit, and thus an analog electronic timepiece, which is capable of carrying out accurate rotation detection by reducing an effect of a load variation, may be constituted.

In addition, the analog electronic timepiece according to each embodiment of the invention is provided with each movement described above, and thus the analog electronic timepiece may carry out accurate rotation detection by reducing the effect due to the load variation, and thus an accurate hand movement operation or low power consumption may be realized.

In addition, in each embodiment of the invention, an example in which the detection section T is basically divided into three sections T 1 to T 3 has been described, but any application is possible as long as the sections are plural in number.

In addition, in a case where the induced current Ik exceeding each of a plurality of reference values is detected plural times in the first section T 1 , each embodiment of the invention is configured to carry out rotation detection by allowing the induced current Ik to flow through the drive coil 209 in a direction opposite to that of the section T 1 in all sections after the section T 1 . However, it may be configured to carry out the rotation detection by allowing the induced current Ik to flow through the drive coil 209 in a direction opposite to that of the section T 1 only in partial sections after the section T 1 .

In addition, the stepping motor control circuit according to each embodiment of the invention is also applicable to a stepping motor that drives components other than the time indicating hands or calendar.

In addition, as an application example of the stepping motor, the electronic timepiece has been described as an example, but the stepping motor is applicable to electronic apparatuses using a motor.

The stepping motor control circuit according to the invention is applicable to various kinds of electronic apparatuses using a stepping motor.

In addition, the movement and the analog electronic timepiece according to the invention are applicable to various kinds of analog electronic timepieces starting from various kinds of analog electronic timepiece with a calendar function such as an analog electronic watch with the calendar function and an analog electronic clock with the calendar function.

Claims as granted

22 claims

Classifications

5 codes

IPC · International Patent Classification

Section G — Physics

G04C3/14

Section H — Electricity

H02P8/02
H02P8/34
H02P8/16
H02P8/38

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