Temperature detection circuit, temperature sensor device and display device

The present disclosure relates to the field of display technology, and in particular to a temperature detection circuit, a temperature sensor device and a display device.

Since the screen integrated temperature sensor has the advantage of not requiring additional extra temperature sensor(s) and being capable of detecting the temperature of the screen as long as being in contact with the screen, and is convenient to use and thus has been widely applied.

In the prior art, the temperature sensor is generally constituted by a ring oscillator, and the temperature detection circuit generally comprises a comparator connected with the ring oscillator. The AC signal output by the ring oscillator is shaped into a square wave signal through the comparator, and the square wave signal is counted by a processor, so as to obtain a frequency of the ring oscillator, and obtain the current screen temperature based on the frequency.

However, since generally the master clock frequency of the processor is limited, when the output frequency of the oscillator is relatively high (reaching above MHZ), it is difficult for the processor to count correctly, causing the temperature detection circuit fail to detect the temperature accurately.

In an aspect, an embodiment of the present disclosure provides a temperature detection circuit, comprising:

a first comparator, the first comparator having a first negative input terminal, a first positive input terminal and a first output terminal, the first negative input terminal being connected with an output terminal of a temperature sensor, the first positive input terminal being connected with a first reference voltage terminal;

a monostable trigger, an input terminal of the monostable trigger being connected with the first output terminal of the first comparator; and

a low pass filter, an input terminal of the low pass filter being connected with an output terminal of the monostable trigger.

In one embodiment, the temperature detection circuit further comprises a differential circuit.

The first output terminal of the first comparator is connected with the input terminal of the monostable trigger through the differential circuit.

In one embodiment, the monostable trigger comprises a second comparator, a first capacitor, a first thin film transistor, a second thin film transistor and a Zener diode. The second comparator has a second negative input terminal, a second positive input terminal and a second output terminal.

The second negative input terminal is connected with an output terminal of the differential circuit. The second positive input terminal is connected with a second reference voltage terminal through a first resistor. The second positive input terminal is further connected with a drain of the first thin film transistor through a second resistor. The second positive input terminal is further connected with a ground terminal through the first capacitor. The second output terminal is connected with a gate of the first thin film transistor through a first voltage dividing circuit. The second output terminal is further connected with a gate of the second thin film transistor through a second voltage dividing circuit.

A source of the first thin film transistor is connected with the ground terminal.

A drain of the second thin film transistor is connected with the second reference voltage terminal through a third resistor. The drain of the second thin film transistor is further connected with the second negative input terminal through a third voltage dividing circuit. A source of the second thin film transistor is connected with the ground terminal.

A positive pole of the Zener diode is connected with the source of the second thin film transistor, and a negative pole of the Zener diode is connected with the drain of the second thin film transistor.

In one embodiment, the differential circuit further comprises a second capacitor and a fourth resistor.

A first terminal of the second capacitor is connected with the first output terminal of the first comparator, and a second terminal of the second capacitor is connected with the second negative input terminal of the second comparator.

The fourth resistor is connected between the second terminal of the second capacitor and the ground terminal.

In one embodiment, the second terminal of the second capacitor is connected with the second negative input terminal of the second comparator through a first diode.

The second output terminal of the second comparator is connected with the first voltage dividing circuit through a second diode, and the second output terminal is further connected with the second voltage dividing circuit through the second diode.

In one embodiment, the temperature detection circuit further comprises a amplitude limiter.

The first negative input terminal of the first comparator is connected with an output terminal of the amplitude limiter, and the first negative input terminal is connected with the output terminal of the temperature sensor through the amplitude limiter.

In one embodiment, the amplitude limiter comprises a third diode and a fourth diode.

A positive pole of the third diode is connected with the first negative input terminal of the first comparator, and a negative pole of the third diode is connected with a third reference voltage terminal.

A negative pole of the fourth diode is connected with the first negative input terminal of the first comparator, and a positive pole of the fourth diode is connected with a fourth reference voltage terminal.

In another aspect, an embodiment of the present disclosure further provides a temperature sensor device, comprising a temperature sensor and the temperature detection circuit as previously described.

The output terminal of the temperature sensor is connected with the first negative input terminal of the first comparator.

In one embodiment, the temperature sensor device further comprises a high pass filter circuit. The output terminal of the temperature sensor is connected with the high pass filter circuit.

The output terminal of the temperature sensor is connected with the first negative input terminal of the first comparator through the high pass filter circuit.

In another aspect, an embodiment of the present disclosure further provides a display device, comprising the temperature sensor device as previously described.

In the technical solution according to an embodiment of the present disclosure, the first negative input terminal of the first comparator is connected with the output terminal of the temperature sensor, and the first positive input terminal of the first comparator is connected with a reference voltage terminal. The first output terminal of the first comparator is connected with the input terminal of the monostable trigger, and the output terminal of the monostable trigger is connected with the input terminal of the low pass filter. In this way, the first comparator shapes the output signal of the temperature sensor into a square wave, and the monostable trigger generates a pulse signal that has the same frequency as the square wave, and has a fixed width which is smaller than the width of the square wave, the low pass filter converts the pulse signal with a fixed width into a frequency dependent DC voltage signal, and the processor performs collecting processing on the frequency dependent DC voltage signal, so as to obtain a current temperature of the screen. Compared with the prior art, the technical solution provided by the embodiment of the present disclosure discards the conventional way of detecting the temperature by counting, but obtains the temperature value by collecting the voltage signal. Thus, the master clock frequency of the processor is not required, which allows the temperature detection circuit to have a relatively wide frequency collecting range. Even if the output frequency of the temperature sensor is relatively high, the temperature detection circuit may also detect the temperature accurately.

FIG. 1 is a structure block diagram of a temperature detection circuit according to an embodiment of the present disclosure;

FIG. 2 is a structure block diagram of another temperature detection circuit according to an embodiment of the present disclosure;

FIG. 3 is a circuit diagram of a temperature detection circuit according to an embodiment of the present disclosure;

FIG. 4 is a circuit diagram of a temperature sensor device according to an embodiment of the present disclosure;

FIG. 5 is a circuit diagram of a high pass filter and a temperature sensor in FIG. 4 ;

FIG. 6 is a schematic structure diagram of a display device according to an embodiment of the present disclosure.

The specific implementations, structures, features and effects of the temperature detection circuit, the temperature sensor device and the display device will be explained in detail below with reference to the drawings and various embodiments. In the following, different “one embodiment” or “an embodiment” does not necessarily refer to an identical embodiment. In addition, particular features or structures in one or more embodiments may be combined in any appropriate form.

As shown in FIG. 1 and FIG. 3 , an embodiment of the present disclosure provides a temperature detection circuit, comprising a first comparator 1 (N 1 ), a monostable trigger 2 and a low pass filter 3 . The first comparator 1 has a first negative input terminal, a first positive input terminal and a first output terminal. The first negative input terminal is connected with an output terminal of a temperature sensor, and the first positive input terminal is connected with a first reference voltage terminal Vref 1 . An input terminal of the monostable trigger 2 is connected with the first output terminal of the first comparator 1 . An input terminal of the low pass filter 3 is connected with an output terminal of the monostable trigger 2 .

The first comparator 1 may use a hysteresis comparator to suppress ringing interference of the output signal of the temperature sensor, so as to ensure accuracy of the output frequency. The AC signal output by the temperature sensor is shaped into a square wave signal having a frequency equal thereto through the first comparator 1 . The monostable trigger 2 outputs a pulse signal having the same frequency as the square wave signal and having a fixed width which is smaller than the width of the square wave signal through delay of resistor and capacitor. The low pass filter 3 converts the pulse signal with a fixed width into a frequency dependent DC voltage signal and outputs it. The processor may perform data processing to the frequency dependent DC voltage signal so as to obtain a frequency value, and then obtain a current temperature value based on the frequency value. In this way, the temperature detection circuit may have a relatively wide frequency collecting range. The width of the pulse signal may be further reduced by adjusting the values of resistance and capacitance in the monostable trigger 2 , so that the detection circuit may have a wider frequency collecting range.

In the temperature detection circuit according to an embodiment of the present disclosure, the first negative input terminal of the first comparator is connected with the output terminal of the temperature sensor, and the first positive input terminal is connected with the first reference voltage. The first output terminal is connected with the input terminal of the monostable trigger, and the output terminal of the monostable trigger is connected with the input terminal of the low pass filter. In this way, the first comparator shapes the output signal of the temperature sensor into a square wave, and the monostable trigger generates a pulse signal having the same frequency as the square wave having a fixed width which is smaller than the width of the square wave. The low pass filter converts the pulse signal with a fixed width into a frequency dependent DC voltage signal, and the processor performs collecting processing on the frequency dependent DC voltage signal, so as to obtain a current temperature. Compared with the prior art, the technical solution provided by the embodiment of the present disclosure discards the conventional way of detecting the temperature by counting, but obtains the temperature value by collecting the voltage signal. Thus, the master clock frequency of the processor is not required, which allows the temperature detection circuit to have a relatively wide frequency collecting range. Even if the output frequency of the temperature sensor is relatively high, the temperature detection circuit may also detect the temperature accurately.

Referring to FIG. 2 and FIG. 3 , the temperature detection circuit further comprises a differential circuit 4 . The first output terminal of the first comparator 1 is connected with the input terminal of the monostable trigger 2 through the differential circuit 4 . The differential circuit 4 shapes the square wave signal output by the first comparator 1 into a pulse signal with a relatively small width. After the pulse signal with a relatively small width is inputted into the monostable trigger 2 , the charging time of the capacitor in the monostable trigger 2 may be shortened, so that the monostable trigger 2 may generate a pulse signal having the same frequency as the square wave signal and having a fixed width and a smaller width, thereby further increases the frequency collecting range of the temperature detection circuit.

Specifically, referring to FIG. 3 or FIG. 4 , the monostable trigger 2 comprises a second comparator N 2 , a first capacitor C 1 , a first thin film transistor T 1 , a second thin film transistor T 2 and a Zener diode D 1 . The second comparator N 2 has a second negative input terminal, a second positive input terminal and a second output terminal. The second negative input terminal is connected with the output terminal of the differential circuit 4 . The second positive input terminal is connected with a second reference voltage terminal Vref 2 through a first resistor R 1 . The second positive input terminal is further connected with a drain of the first thin film transistor T 1 through a second resistor R 2 . The second positive input terminal is further connected with the ground terminal through the first capacitor C 1 . The second output terminal is connected with a gate of the first thin film transistor T 1 through a first voltage dividing circuit 21 . The second output terminal is further connected with a gate of the second thin film transistor T 2 through a second voltage dividing circuit 22 . The source of the first thin film transistor T 1 is connected with the ground terminal. The drain of the second thin film transistor T 2 is connected with the second reference voltage terminal Vref 2 through a third resistor R 3 . The drain of the second thin film transistor T 2 is also connected with the second negative input terminal through the third voltage dividing circuit 23 . The source of the second thin film transistor T 2 is connected with the ground terminal. The positive pole of the Zener diode D 1 is connected with the source of the second thin film transistor T 2 . The negative pole of the Zener diode D 1 is connected with the drain of the second thin film transistor T 2 . The differential circuit 4 comprises a second capacitor C 2 and a fourth resistor R 4 . The first terminal of the second capacitor C 2 is connected with the first output terminal of the first comparator. The second terminal of the second capacitor C 2 is connected with the second negative input terminal of the second comparator. The fourth resistor R 4 is connected between the second terminal of the second capacitor C 2 and the ground terminal. The first voltage dividing circuit 21 may comprise two resistors R 5 and R 6 connected in series between the second output terminal of the second comparator and the ground terminal. The gate of the first thin film transistor T 1 is connected between the two resistors R 5 and R 6 . The second voltage dividing circuit 22 may comprise two resistors R 7 and R 8 connected in series between the second output terminal of the second comparator and the ground terminal. The gate of the second thin film transistor T 2 is connected between the two resistors R 7 and R 8 . The third voltage dividing circuit 23 may comprise two resistors R 9 and R 10 connected in series between the drain of the second thin film transistor T 2 and the ground terminal. The second negative input terminal of the second comparator is connected between the two resistors R 9 and R 10 .

The working process of the monostable trigger 2 is:

First stage: when the potential of the square wave signal U 1 output by the first output terminal of the first comparator 1 is at a low level, the potential of the pulse signal output from the differential circuit 4 is also at a low level. At this time, since the second positive input terminal U 22 of the second comparator N 2 is connected with the second reference voltage terminal Vref 2 , the potential of the second positive input terminal U 22 of the second comparator N 2 is greater than the potential of the second negative input terminal U 21 , such that the output signal of the second output terminal of the second comparator N 2 is at a high level. The high level meets the turn-on conditions of the first thin film transistor T 1 and the second thin film transistor T 2 , such that the first thin film transistor T 1 and the second thin film transistor T 2 are both turned on. At this time, the potential of the drain of the second thin film transistor T 2 , i.e., the output terminal U 2 of the monostable trigger 2 , is at a low level, and the frequency of the output signal is same as that of the input signal, the potential of the first positive input terminal U 22 of the second comparator N 2 is also at a low level.

Second stage: when the potential of the square wave signal U 1 output by the first output terminal of the first comparator 1 is at a high level, the potential of the pulse signal output from the differential circuit 4 becomes a high level. At this time, since the potential of the second positive input terminal U 22 of the second comparator N 2 is at a low level, the potential of the second positive input terminal U 22 of the second comparator N 2 is less than that of the second negative input terminal U 21 , such that the output signal of the second output terminal of the second comparator N 2 is at a low level. This low level could not meet the turn-on conditions of the first thin film transistor T 1 and the second thin film transistor T 2 , such that the first thin film transistor T 1 and the second thin film transistor T 2 are both turned off. At this time, the second thin film transistor T 2 is turned off, the second reference voltage terminal Vref 2 enables the Zener diode D 1 to turn on through the third resistor R 3 , so as to enable the output terminal U 2 of the monostable trigger 2 to be a stable voltage of the Zener diode D 1 . Meanwhile, the pulse signal output from the differential circuit 4 remains at a high potential due to the voltage division action of the third voltage dividing circuit 23 . The first thin film transistor T 1 is turned off, the second reference voltage terminal Vref 2 charges the first capacitor C 1 through the first resistor R 1 , so as to enable the potential of the second positive input terminal U 22 of the second comparator N 2 to rise gradually. Until the potential of the second positive input terminal U 22 of the second comparator N 2 is higher than the potential of the pulse signal output from the differential circuit 4 , the second output terminal of the second comparator N 2 outputs a high level again, the first thin film transistor T 1 and the second thin film transistor T 2 are turned on again. The first stage is repeated, and the potential of the output terminal U 2 of the monostable trigger 2 is at a low level, and thus the monostable process ends.

Specifically, referring to FIG. 3 or FIG. 4 , the second terminal of the second capacitor C 2 is connected with the second negative input terminal of the second comparator through the first diode D 2 . The second output terminal of the second comparator is connected with the first voltage dividing circuit 21 through the second diode D 3 . The second output terminal is further connected with the second voltage dividing circuit 22 through the second diode D 3 . The unidirectional conduction of the circuit is ensured by arranging the first diode D 2 and the second diode D 3 , so as to ensure normal operation of the circuit.

Since the output signal of the temperature sensor might form a spike due to instability, in order to prevent the spike from damaging the temperature detection circuit, the temperature detection circuit may further comprise an amplitude limiter 5 . The first negative input terminal of the first comparator is connected with the output terminal of the amplitude limiter 5 , and the first negative input terminal of the first comparator is connected with the output terminal of the temperature sensor through the amplitude limiter 5 . The output signal of the temperature sensor is inputted to the first comparator 1 again after being limited by the amplitude limiter 5 , thereby eliminating the spike that might occur in the output signal of the temperature sensor, and ensuring the normal operation of the temperature detection circuit.

Specifically, referring to FIG. 3 or FIG. 4 , the amplitude limiter 5 may comprise a third diode D 4 and a fourth diode D 5 . The positive pole of the third diode D 4 is connected with the first negative input terminal of the first comparator, and the negative pole of the third diode D 4 is connected with a third reference voltage terminal Vref 3 . The negative pole of the fourth diode D 5 is connected with the first negative input terminal of the first comparator, and the positive pole of the fourth diode D 5 is connected with a fourth reference voltage terminal Vref 4 . The voltage value of the input signal Uin (i.e., the output signal of the temperature sensor) that enters the amplitude limiter 5 may be kept between the third reference voltage Vref 3 output by the third reference voltage terminal and the fourth reference voltage Vref 4 output by the fourth reference voltage terminal. Therefore, the spike in the output signal of the temperature sensor is effectively prevented from entering the first comparator 1 , which ensures normal operation of the temperature detection circuit. The third reference voltage value output by the third reference voltage terminal Vref 3 may be equal to the second reference voltage value output by the second reference voltage terminal Vref 2 .

As shown in FIG. 4 , an embodiment of the present disclosure further provides a temperature sensor device, comprising a temperature sensor 6 and the temperature detection circuit as previously described. The output terminal of the temperature sensor 6 may be connected with the first negative input terminal of the first comparator 1 .

The temperature sensor device provided by the embodiment of the present disclosure comprises a temperature detection circuit. In the temperature detection circuit, the first negative input terminal of the first comparator is connected with the output terminal of the temperature sensor, the first positive input terminal is connected with the first reference voltage, the first output terminal is connected with the input terminal of the monostable trigger, and the output terminal of the monostable trigger is connected with the input terminal of the low pass filter. In this way, the first comparator shapes the output signal of the temperature sensor into a square wave, and the monostable trigger generates a pulse signal having the same frequency as the square wave having a fixed width which is smaller than the width of the square wave. The low pass filter converts the pulse signal with a fixed width into a frequency dependent DC voltage signal, and the processor performs collecting processing on the frequency dependent DC voltage signal, so as to obtain a current temperature. Compared with the prior art, the technical solution provided by the embodiment of the present disclosure discards the conventional way of detecting the temperature by counting, but obtains the temperature value by collecting the voltage signal. Thus, the master clock frequency of the processor is not required, which allows the temperature detection circuit to have a relatively wide frequency collecting range. Even if the output frequency of the temperature sensor is relatively high, the temperature detection circuit may also detect the temperature accurately.

At present, in addition to the AC component formed by oscillation, the signal output by the temperature sensor constituted by the ring oscillator may further contain DC components due to factors such as errors in the manufacturing process of the device per se. Moreover, part of the DC components may vary due to different temperature sensors, which requires the first reference voltage value output by the first reference voltage terminal connected with the first positive input terminal of the first comparator in the temperature detection circuit to be adjusted according to different DC components. In order to solve this problem, the output terminal of the temperature sensor 6 is connected with a high pass filter circuit 7 . The output terminal of the temperature sensor 6 may be connected with the first negative input terminal of the first comparator 1 through the high pass filter circuit 7 . The DC components in the output signal of the temperature sensor 6 may be filtered through the high pass filter 7 , so that the output signal only contains AC components, so that the first positive input terminal of the first comparator 1 only has to be connected with the ground. In this way, when detecting different temperature sensors, it is not necessary to adjust the temperature detection circuit, so that the efficiency is improved and reduce the cost. The high pass filter 7 may also be connected with the input terminal of the amplitude limiter 5 , and connected with the first negative input terminal of the first comparator through the amplitude limiter 5 . The high pass filter 7 may also be arranged in the temperature detection circuit, so as to implement the function of filtering the DC components in the output signal of the temperature sensor. If the high pass filter is arranged in the temperature detection circuit, the high pass filter will be relatively far away from the temperature sensor. Hence, the detection effect obtained from such a design might be different from the detection effect obtained by arranging the high pass filter on the temperature sensor directly.

FIG. 5 shows a specific implementation of mutual connection of the temperature sensor 6 and the high pass filter 7 . Each inverter in the temperature sensor 6 is constituted by a switch transistor T 3 and a switch transistor T 4 . The specific working principle thereof is the prior art, which will not be repeated herein.

As shown in FIG. 6 , an embodiment of the present disclosure further provides a display device, comprising the temperature sensor device as previously described. The display device may be a display screen. The capacitor of the high pass filter in the temperature sensor may be manufactured in the back plate of thin film transistor of the display screen. The specific manufacturing scheme may take the low temperature polysilicon process as an example, and take the pixel electrode layer, the insulating layer and the common electrode in the back plate as the capacitor. The temperature sensor may be manufactured in the non-display area, for example, the free area in the fan-out area below the display screen, and may also be integrated in the non-display area between the pixel areas. The numeral “ 10 ” in FIG. 6 represents the temperature sensor. It should be noted that in such a case, in order to reduce the amount of wirings, a thin film transistor may be added before the temperature sensor is elicited, and a column of temperature sensors may share one read line, so as to read the temperature signal in line by line scanning manner. Moreover, the temperature sensor detection mode in this case may share a read line with display and perform time multiplexing with the display.

The display device provided by the embodiment of the present disclosure comprises a temperature sensor device. The temperature sensor device comprises a temperature detection circuit. The first negative input terminal of the first comparator of this temperature detection circuit is connected with the output terminal of the temperature sensor, and the first positive input terminal is connected with the first reference voltage. The first output terminal is connected with the input terminal of the monostable trigger, and the output terminal of the monostable trigger is connected with the input terminal of the low pass filter. In this way, the first comparator shapes the output signal of the temperature sensor into a square wave, and the monostable trigger generates a pulse signal having the same frequency as the square wave having a fixed width which is smaller than the width of the square wave. The low pass filter converts the pulse signal with a fixed width into a frequency dependent DC voltage signal, and the processor performs collecting processing on the frequency dependent DC voltage signal, so as to obtain a current temperature. Compared with the prior art, the technical solution provided by the embodiment of the present disclosure discards the conventional way of detecting the temperature by counting, but obtains the temperature value by collecting the voltage signal. Thus, the master clock frequency of the processor is not required, which allows the temperature detection circuit to have a relatively wide frequency collecting range. Even if the output frequency of the temperature sensor is relatively high, the temperature detection circuit may also detect the temperature accurately.

What are described above are only specific implementations of the present disclosure. However, the protection scope of the present disclosure is not limited to this. Any modifications or replacements that may be easily conceived by the skilled person familiar with the present technical field within the technical scope disclosed by the present disclosure shall be encompassed within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scopes of the claims attached.