Light adjusting device with switching element

This application claims the benefit of Taiwan application Serial No. 102131376, filed Aug. 30, 2013, the subject matter of which is incorporated herein by reference.

1. Field of the Invention

The invention relates in general to a light adjusting device, and more particularly to a light adjusting device incorporating a switch element to simplify circuit complexity.

2. Description of the Related Art

Conventional light source of lighting apparatus provides a steady light output at all times. However, the user can only control the light source to be either in a light state or a dark state by turning on or turning off the power, and cannot adjust the luminance of a lighting apparatus according to the scenarios of use. Most of the currently available light adjusting technologies require the use of a complicated circuit structure, not only increasing production cost but also making the installation of circuit more difficult.

Therefore, how to simplify circuit complexity and reduce production cost for light adjusting device has become a prominent task for the industries.

The invention is directed to a light adjusting device incorporating a switch element to simplify the complexity of circuit structure.

According to one embodiment of the present invention, a light adjusting device for adjusting the luminance of a light source is provided. The light adjusting device comprises a rectifier module, a first switch element, a second switch element and a control module. The rectifier module receives an AC signal from a first power node and a second power node, and rectifies the AC signal to output a driving signal to the light source. The first switch element is coupled to the first power node. The second switch element is coupled to the second power node. The control module outputs a control signal to the first and second switch elements to control the conduction states of the first and second switch elements. When the first and second switch elements are turned on, the driving signal provided to the light source is interrupted.

According to another embodiment of the present invention, a light adjusting device for rectifying the luminance of a light source is provided. The light adjusting device comprises a rectifier module, a first switch element and a second switch element. The rectifier module comprises a first diode, a second diode, a third diode and a fourth diode. The first diode is coupled between the first power node and the first node and forward biased towards the first node. One terminal of the light source is coupled to the first node. The second diode is coupled between a second power node and the first node and forward biased towards the first node. The third diode is coupled between the second power node and a second node and forward biased towards the second power node. The other terminal of the light source is coupled to the second node. The fourth diode is coupled between the first power node and the second node and forward biased towards the first power node. The first switch element is coupled between the first power node and the second node. The second switch element is coupled between the second power node and the second node. Each of the first and second switch elements has a control terminal for receiving a control signal which controls the conduction states of the first and second switch elements, and determines whether to provide a driving signal to the light source.

The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s).The following description is made with reference to the accompanying drawings.

FIG. 1 is a block diagram of a light adjusting device according to an embodiment of the present invention.

FIG. 2A is an example of a circuit diagram of a light adjusting device when first and second switch elements are turned off and the AC signal is in a positive half-cycle.

FIG. 2B is an example of a circuit diagram of a light adjusting device when first and second switch elements are turned off and the AC signal is in a negative half-cycle.

FIG. 2C is an example of a circuit diagram of a light adjusting device when first and second switch elements are turned on and the AC signal is in a positive half-cycle.

FIG. 2D is an example of a circuit diagram of a light adjusting device when first and second switch elements are turned on and the AC signal is in a negative half-cycle.

FIG. 3A is a measurement chart of output current of a light source when the duty cycle of a control signal is at 0%.

FIG. 3B is a measurement chart of output current of a light source when the duty cycle of a control signal is at 90%.

Referring to FIG. 1 , a block diagram of a light adjusting device 100 according to an embodiment of the present invention is shown. The light adjusting device 100 adjusts the luminance of a light source 102 . As indicated in FIG. 1 , the light adjusting device 100 comprises a rectifier module 106 , a first switch element S 1 , a second switch element S 2 and a control module 108 . The rectifier module 106 receives an AC signal I A from a first power node N P1 and a second power node N P2 , and further rectifies the AC signal to output a driving signal I D to the light source 102 . The first switch element S 1 is coupled to the first power node N P1 . The second switch element S 2 is coupled to the second power node N P2 . The control module 108 outputs a control signal CS to the first and second switch elements S 1 and S 2 to control the conduction states of the first and second switch elements S 1 and S 2 . When the first and second switch elements S 1 and S 2 are turned on, the driving signal I D provided to the light source 102 is interrupted.

The light source 102 can be realized by a light emitting diode (LED), an organic light emitting diode (OLED) or other solid-state light source. The first power node N P1 and the second power node N P2 are respectively coupled to a live line terminal T L and a neutral line terminal T N of a power 104 for receiving an AC signal I A from the power 104 . The power 104 can be realized by an AC voltage source, a supply main, or other energy source capable of generating an AC output for a lighting apparatus. The rectifier module 106 can be realized by a full-wave rectifier capable of rectifying the AC signal I A into a DC driving signal I D . The control module 108 can be realized by a pulse width modulation (PWM) signal generator capable of generating a PWM signal used as a control signal CS. However, the present invention is not limited to the above exemplifications.

As indicated in FIG. 1 , one terminal of the rectifier module 106 and one terminal of the light source 102 are coupled to the first node N 1 ; the other terminal of the rectifier module 106 and the other terminal of the light source 102 are coupled to the second node N 2 . The driving signal I D flows to the second node N 2 from the first node N 1 for enabling the light source 102 to emit a light having particular luminance and/or color temperature.

In an example, the light adjusting device 100 further comprises a filter module 110 coupled between the first node N 1 and the second node N 2 for filtering the driving signal I D to output a filtered driving signal I D . The filter module 110 can be realized by a capacitor capable of low-pass filtering the driving signal I D to smooth the wave pattern of the driving signal I D (that is, the filtered driving signal I D ). However, the present invention is not limited to the above exemplification, and the filter module 110 can also be realized by other low-pass filters.

In the present embodiment, each of the first and second switch elements S 1 and S 2 has a control terminal for receiving a control signal CS from the control module 100 . For instance, each of the first and second switch elements S 1 and S 2 can be realized by a silicon controlled rectifier (SCR) which determines whether to turn on the current in a one way manner based on the control signal CS received at the control terminal. Taking the control signal CS being a PWM signal for example, when the control signal CS is at a low level, the first and second switch elements S 1 and S 2 are turned off. Conversely, when the control signal CS is at a high level, the first and second switch elements S 1 and S 2 are turned on, and the current can flow from one terminal of the first switch element S 1 or the second element S 2 (such as the first power node NP 1 or the second power node NP 2 ) to the other terminal of the first switch element S 1 or the second element S 2 (such as the ground terminal). However, the present invention is not limited to the above exemplification, and any three-terminal elements capable of determining whether to turn on the current in a one way manner based on the received control signal can be used as the first switch element S 1 or the second element S 2 of the present invention embodiment.

FIG. 2A to FIG. 2D are disclosed below for elaborating the operation of the light adjusting device 100 of an embodiment of the present invention. However, the circuit structure of each module is for detailed descriptions only, not for limiting the scope of protection of the invention.

Referring to FIG. 2A , an example of a circuit diagram of a light adjusting device 100 when first and second switch elements S 1 and S 2 are turned off and the AC signal I A is in a positive half-cycle is shown. As indicated in FIG. 2A , the rectifier module 106 comprises a first diode D 1 , a second diode D 2 , a third diode D 3 and a fourth diode D 4 . The first diode D 1 is coupled between the first power node N P1 and the first node N 1 and forward biased towards the first node N 1 . The second diode D 2 is coupled between the second power node N P2 and the first node N 1 and forward biased towards the first node N 1 . The third diode D 3 is coupled between the second power node N P2 and the second node N 2 and forward biased towards the second power node N P2 . The fourth diode D 4 is coupled between the first power node N P1 and the second node N 2 and forward biased towards the first power node N P1 . In the present example, the filter module 110 is realized by a capacitor Cf coupled between the first node N 1 and the second node N 2 . Each of the first and second switch elements S 1 and S 2 is realized by a silicon controlled rectifier (SCR).

In the present example, the control module 108 outputs a low-level control signal CS (indicating a turn-off state) to the control terminals of the first and second switch elements S 1 and S 2 for turning off the first and second switch elements S 1 and S 2 . Meanwhile, the AC signal I A at a positive half-cycle forms a power supply loop (indicated by arrows in dotted lines) along the first power node N P1 →the first diode D 1 of the rectifier module 106 →the light source 102 →the third diode D 3 →the second power node N P2 , such that the light source 102 receives a full-load power supply and illuminates.

Referring to FIG. 2B , an example of a circuit diagram of a light adjusting device 100 when first and second switch elements S 1 and S 2 are turned off and the AC signal I A is in a negative half-cycle is shown. Like FIG. 2A , the control module 108 outputs a low-level control signal CS (indicating a turn-off state) to the control terminals of the first and second switch elements S 1 and S 2 for turning off the first and second switch elements S 1 and S 2 . Meanwhile, the AC signal I A at a negative half-cycle forms a power supply loop (indicated by arrows in dotted lines) along the second power node N P2 →the second diode D 2 of the rectifier module 106 →the light source 102 →the fourth diode D 4 →the first power node N P1 , such that the light source 102 receives a full-load power supply and illuminates.

Referring to FIG. 2C , an example of a circuit diagram of a light adjusting device 100 when first and second switch elements S 1 and S 2 are turned on and the AC signal I A is in a positive half-cycle is shown. In the present example, the control module 108 outputs a high-level control signal CS (indicating a turn-on state) to the control terminals of the first and second switch elements S 1 and S 2 for turning on the first and second switch elements S 1 and S 2 . Meanwhile, the AC signal I A at a positive half-cycle forms a loop current (indicated by arrows in dotted lines) along the first power node N P1 →the first switch element S 1 →the third diode D 3 of the rectifier module 106 →the second power node N P2 . Since the loop current does not flow through the light source 102 , the power supply of the light source 102 will be terminated during the positive half-cycle.

Referring to FIG. 2D , an example of a circuit diagram of a light adjusting device 100 when first and second switch elements S 1 and S 2 are turned on and the AC signal I A is in a negative half-cycle is shown. Like FIG. 2C , the control module 108 outputs a high-level control signal CS (indicating a turn-on state) to the control terminals of the first and second switch elements S 1 and S 2 for turning of the first and second switch elements S 1 and S 2 . Meanwhile, the AC signal I A at a negative half-cycle forms a loop current (indicated by arrows in dotted lines) along the second power node N P2 →the second switch element S 2 →the fourth diode D 4 of the rectifier module 106 →the first power node N P1 . Since the loop current does not flow through the light source 102 , the power supply of the light source 102 will be terminated during the negative half-cycle.

Referring to FIG. 3A and FIG. 3B , measurement charts of output current of a light source 102 (exemplified by an LED string) when duty cycle of control signal CS is at 0% and 90% respectively are shown. As indicated in FIG. 3A , when the duty cycle of the control signal CS is equal to 0%, this indicates that the first and second switch elements S 1 and S 2 are turned off (or not operating). Meanwhile, when the output current of the light source 102 is about 0.8 ampere, this indicates that the light source 102 is operated at full load. Conversely, as indicated in FIG. 3B , when the duty cycle of the control signal CS is equal to 90%, this indicates that the first and second switch elements S 1 and S 2 are turned on (or are operating). Meanwhile, the output current of the light source 102 is about 0.24 ampere, which deteriorates the luminance of the light source 102 . The working conditions and measurement results are for verifying the effect of the light adjusting device 100 of disclosed embodiments of the present invention, not for limiting the scope of protection of the present invention.

The light adjusting device of disclosed embodiments of the present invention achieves the effect of adjusting the light source by controlling the conduction states of the first and second switch elements coupled to the power, not only largely simplifying circuit complexity but also reducing production cost and manufacturing labor.

While the invention has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.