TW202340682A - High-sensitivity light sensor and sensing method thereof - Google Patents

Abstract

A high-sensitivity light sensor includes a light sensing element, a first integrator, a comparator, and a second integrator. The light sensing element senses a light during a measurement time to generate a current. The first integrator integrates the current to generate a first integration signal. The comparator compares the first integration signal and a threshold, wherein when the first integration signal is greater than the threshold, the comparison signal has a first level. The light sensor of the present invention uses the second integrator to obtain the residual voltage between the last comparison signal and the end of the measurement time, to more accurately determine an intensity of the light, so that the light sensor of the present invention has a higher sensitivity.

Description

High-sensitivity light sensor and sensing method thereof

The present invention relates to a light sensor, and in particular to a light sensor for sensing ambient light and a sensing method thereof.

The light sensor can be used to sense ambient light to determine the intensity of ambient light. Traditional ambient light sensors use a photo diode to sense ambient light to generate a current, and use an analog-to-digital conversion circuit to convert the current into a digital value to determine light intensity. However, there may be an error between the ambient light intensity calculated by the existing ambient light sensor and the actual ambient light intensity. Recently, many electronic devices have increasingly higher requirements for the sensitivity of light sensors, and traditional ambient light sensors no longer meet the requirements. Therefore, a high-sensitivity light sensor is desired.

The purpose of the present invention is to provide a high-sensitivity light sensor and a sensing method thereof.

According to the present invention, a high-sensitivity light sensor includes a light sensing element, a first integrator, a first comparator, a first reset circuit, a first counter, a second integrator, and a a second comparator, a second reset circuit and a second counter. The light sensing element senses a light at a measurement time and generates a first current. The first integrator is coupled to the light sensing element and used to integrate the first current to generate a first integrated signal. The first comparator is coupled to the first integrator and used to compare the first integrated signal with a critical value to generate a first comparison signal. When the first integrated signal is greater than the critical value, the first comparison signal As a first level. The first reset circuit is coupled to the first integrator and the first comparator, and is used to reset the first integration signal when the first comparison signal is at the first level. The first counter is coupled to the first comparator and used to count the number of times the first comparison signal reaches the first level to generate a first sensing value. The second integrator is coupled to the first integrator and used to integrate the first integrated signal to generate a second integrated signal. The second comparator is coupled to the second integrator and used to compare the second integrated signal with the critical value to generate a second comparison signal. When the second integrated signal is greater than the critical value, the second comparison signal It is a second level. The second reset circuit is coupled to the second integrator and the second comparator, and is used to reset the second integration signal when the second comparison signal is at the second level. The second counter is coupled to the second comparator and used to count the number of times the second comparison signal reaches the second level to generate a second sensing value. Wherein, when the first comparison signal is at the first level, the second counter is reset. When the measurement time ends, the first sensing value and the second sensing value are used to determine the intensity of the light.

According to the present invention, a high-sensitivity light sensor includes a light sensing element, a first integrator, a first comparator, a timer, a first reset circuit, a second integrator, a first two comparators, a second reset circuit and a counter. The light sensing element senses a light at a measurement time and generates a first current. The first integrator is coupled to the light sensing element and used to integrate the first current to generate a first integrated signal. The first comparator is coupled to the first integrator and used to compare the first integrated signal with a critical value to generate a first comparison signal. When the first integrated signal is greater than the critical value, the first comparison signal As a first level. The timer is coupled to the first comparator and is used to calculate a first time length between two adjacent first levels of the first comparison signal after the measurement time starts, and calculate the third A second length of time between the last first level of a comparison signal and the end of the measurement time. The first reset circuit is coupled to the first integrator and the first comparator, and is used to reset the first integration signal when the first comparison signal is at the first level. The second integrator is coupled to the first integrator and used to integrate the first integrated signal to generate a second integrated signal. The second comparator is coupled to the second integrator and used to compare the second integrated signal with the critical value to generate a second comparison signal. When the second integrated signal is greater than the critical value, the second comparison signal It is a second level. The second reset circuit is coupled to the second integrator and the second comparator, and is used to reset the second integration signal when the second comparison signal is at the second level. The counter is coupled to the second comparator and used to count the number of times the second comparison signal is at the second level and generate a sensing value; wherein, when the first comparison signal is at the first level, the The light sensor stores the sensing value and resets the second counter; when the measurement time ends, all the stored sensing values and the current sensing value are used to determine the intensity of the light. intensity.

According to the present invention, a sensing method of a high-sensitivity light sensor includes the following steps: using a light sensing element to sense a light at a measurement time to generate a first current; integrating the first current to generate a first integrated signal; converting the first integrated signal into a first sensing value; integrating the first integrated signal to generate a second integrated signal; generating a second sensing value according to the second integrated signal; and The first sensing value and the second sensing value determine the intensity of the light.

According to the present invention, a sensing method of a high-sensitivity light sensor includes the following steps: using a light sensing element to sense a light at a measurement time to generate a first current; integrating the first current to generate A first integrated signal; integrating the first integrated signal to generate a second integrated signal; generating a sensing value based on the second integrated signal; and determining the intensity of the light based on the sensing value.

The light sensor and its sensing method of the present invention can obtain more accurate sensing results and have higher sensitivity.

Figure 1 shows a first embodiment of a high-sensitivity photo sensor of the present invention. FIG. 2 shows the waveforms of the integrated signal Pout and the comparison signal D1 in FIG. 1 at the measurement time Ts. The light sensor 30 of FIG. 1 includes a light sensing element (such as a photodiode 31), a reset circuit 32, an integrator 33, a comparator 34, a counter 35, a timer 36, and a reset circuit. Circuit 37, an integrator 38, a comparator 39, and a counter 40. The photodiode 31 is used to sense an ambient light or a light ray to generate a current Ip. The integrator 33 integrates the current Ip' to generate an integrated signal Pout. When the switch SW1 of the reset circuit 32 is not closed, the current Ip'=Ip. The integrator 33 includes an operational amplifier 331, a switch SW13 and a capacitor CF1. The inverting input terminal of the operational amplifier 331 is connected to the photodiode 31, and the non-inverting input terminal of the operational amplifier 331 is connected to a ground terminal GND. The operational amplifier 331 The output terminal is connected to the non-inverting input terminal of the comparator 34, the capacitor CF1 is connected between the inverting input terminal and the output terminal of the operational amplifier 331, the switch SW13 is connected in parallel with the capacitor CF1 and is controlled by the signal Pr. In one embodiment, the signal Pre is provided by a circuit control unit (not shown in the figure). During the measurement time Ts, the signal Pr controls the switch SW13 to turn off. When the signal Pr controls the switch SW13 to be closed (on), the integrator 33 enters the reset state. At this time, the integration signal Pout is reset back to a starting value, and the integrator 33 stops integrating the current Ip'. When the signal Pr controls the switch SW13 to turn off, the integrator 33 leaves the reset state and starts integrating the current Ip', causing the integrated signal Pout to rise. Comparator 34 is connected to integrator 33 . The comparator 34 is used to compare the integrated signal Pout output by the integrator 33 with a reference voltage Vref as a threshold value. When the integrated signal Pout is greater than the reference voltage Vref, the comparison signal D1 output by the comparator 34 becomes a high level (i.e., the first level) D1_H, but the present invention is not limited to this. The reset circuit 32 is connected to the integrator 33 and the comparator 34 . The reset circuit 32 resets the integration signal Pout back to the starting value when the comparison signal D1 is at the high level D1_H. The reset circuit 32 includes a voltage source (not shown in the figure) and a switched capacitor (switch-C) circuit, where the voltage source may be a voltage source that provides a reference voltage Vref. The switched capacitor circuit includes a capacitor C1 and four switches SW1, SW2, SW3 and SW4. The switch SW1 is connected between the first end of the capacitor C1 and the photodiode 31, and the switch SW2 is connected between the second end of the capacitor C1 and the photodiode 31. Between the voltage sources (Vref), the switch SW3 is connected between the second terminal of the capacitor C1 and the ground terminal GND, and the switch SW4 is connected between the first terminal of the capacitor C1 and the ground terminal GND. The switches SW1 and SW2 are controlled by the comparison signal D1, and the switches SW3 and SW4 are controlled by the signal, where the signal is the inverse signal of the comparison signal D1. When the comparison signal D1 is at the high level D1_H, as shown in FIG. 2 , the switches SW1 and SW2 are closed and the switches SW3 and SW4 are opened. At this time, the reset circuit 32 is activated to generate the reset current If1 , so that the integral signal Pout is reset back to the starting value, where t1 is the length of time that the switches SW1 and SW2 are closed. The counter 35 is used to count the number of times the comparison signal D1 appears at a high level within the measurement time Ts to generate a sensing value O1.

The reset circuit 32, the integrator 33, the comparator 34 and the counter 35 can be regarded as an analog-to-digital converter for converting the analog current Ip' into a digital sensing value O1. The timer 36 is connected to the output end of the comparator 34 and calculates the time length Ti between two adjacent high levels D1_H of the comparison signal D1 and the time between the last high level D1_H and the end of the measurement time Ts based on the clock signal CK. The time length T', where Ti refers to the time length between the i-1th high level D1_H and the i-th high level D1_H in the comparison signal D1. For example, as shown in Figure 2, the time length T1 refers to The time length between the 0th high level D1_H of the comparison signal (i.e., the starting point of the measurement time Ts) and the 1st high level D1_H, and the time length T2 refers to the 1st high level D1_H to the 1st high level D1_H. The length of time between two high levels D1_H. In the embodiment of FIG. 1, the timer 36 sends out the time length T' at the end of the measurement time Ts.

As shown in FIG. 1 , the integrator 38 is connected to the output end of the operational amplifier 331 in the integrator 33 to integrate the integration signal Pout to generate the integration signal Aout. The integrator 38 includes an impedance circuit 381, an operational amplifier 382, a switch SW14 and a capacitor CF2. The impedance circuit 381 is connected between the integrator 33 and the inverting input terminal of the operational amplifier 382 for converting the integrated signal Pout into a current signal I1. The impedance circuit 381 includes a capacitor C2 and four switches SW5, SW6, SW7 and SW8. The switch SW5 is connected between the first terminal of the capacitor C2 and the integrator 33, and the switch SW6 is connected between the second terminal of the capacitor C2 and the operational amplifier. Between the inverting input terminals of 382, switch SW7 is connected between the second terminal of capacitor C2 and ground terminal GND, and switch SW8 is connected between the first terminal of capacitor C2 and ground terminal GND. The switches SW5 and SW6 are controlled by the clock signal CK, and the switches SW7 and SW8 are controlled by a clock signal inverted with the clock signal CK. When the switches SW5 and SW6 are turned off and the switches SW7 and SW8 are turned on, the charge on the capacitor C2 is cleared. When switches SW5 and SW6 are closed and switches SW7 and SW8 are opened, capacitor C2 generates current signal I1 , where t2 is the closing time length of SW5 and SW6. The equivalent resistance R of the impedance circuit 381 is . In FIG. 1 , the impedance circuit 381 is a switched capacitor circuit, but the invention is not limited thereto. The non-inverting input terminal of the operational amplifier 382 is connected to the ground terminal GND, the output terminal of the operational amplifier 382 is connected to the non-inverting input terminal of the comparator 39, and the capacitor CF2 is connected between the inverting input terminal and the output terminal of the operational amplifier 382. The switch SW14 is connected in parallel with the capacitor CF2 and is controlled by the comparison signal D1. When the comparison signal D1 is at the high level D1_H, the switch SW14 is closed (on), and the integrator 38 enters the reset state. At this time, the integral signal Aout is reset to a starting value, and the integrator 38 stops processing the integral signal Pout. Points. When the comparison signal D1 is at the low level D1_L, the switch SW14 is turned off, the integrator 38 leaves the reset state and starts integrating the integration signal Pout, causing the integration signal Aout to rise.

The comparator 39 of Figure 1 is connected to the integrator 38. The comparator 39 is used to compare the integrated signal Aout output by the integrator 38 with the reference voltage Vref. When the integrated signal Aout is greater than the reference voltage Vref, the comparison signal D2 generated by the comparator 39 is a high level (ie, the second level) D2_H. (not shown in the figure), but the present invention is not limited to this. The reset circuit 37 connects the integrator 38 and the comparator 39 . The reset circuit 37 resets the integration signal Aout back to the starting value when the comparison signal D2 is at the high level D2_H. The reset circuit 37 includes a voltage source (not shown in the figure) and a switched capacitor circuit, where the voltage source may be a voltage source that provides a reference voltage Vref. The switched capacitor circuit includes a capacitor C3 and four switches SW9, SW10, SW11 and SW12. The switch SW9 is connected between the first terminal of the capacitor C3 and the voltage source, and the switch SW10 is connected between the second terminal of the capacitor C3 and the operational amplifier. Between the inverting input terminals of the 382, the switch SW11 is connected between the second terminal of the capacitor C3 and the ground terminal GND, and the switch SW12 is connected between the first terminal of the capacitor C3 and the ground terminal GND. The switches SW9 and SW10 are controlled by the comparison signal D2, and the switches SW11 and SW12 are controlled by the signal, where the signal is the inverse signal of the comparison signal D2. When the comparison signal D2 is at a high level, the switches SW9 and SW10 are closed and the switches SW11 and SW12 are opened. At this time, the reset circuit 37 generates a reset current. , so that the integral signal Aout is reset back to the starting value, where t3 is the length of time that the switches SW9 and SW10 are closed. The counter 40 is connected to the comparators 34 and 39 for counting the number of times of the high level D2_H of the comparison signal D2 to generate a sensing value O2. When the comparison signal D1 of the comparator 34 is the high level D1_H, the counter 40 will be reset so that the sensing value O2 returns to 0. The reset circuit 37, the integrator 38, the comparator 39 and the counter 40 can be regarded as an analog-to-digital converter.

At the end of the measurement time Ts, based on the sensing value O1 and the sensing value O2, the sensing value O=O1+h'=O1+ representing the ambient light (or light) intensity can be calculated . Since the light sensor 30 of the present invention can further calculate the remaining area 20, it can obtain more accurate sensing results with higher sensitivity.

From the above description, it can be understood that the sensing method of the light sensor 30 of the present invention includes the following steps: Use a light sensing element to sense a light at a measurement time to generate a first current; Integrate the first current to generate a first integrated signal; Convert the first integrated signal into a first sensing value; Integrate the first integrated signal to generate a second integrated signal; Generate a second sensing value according to the second integrated signal; and The intensity of the light is determined based on the first sensing value and the second sensing value.

In the sensing method of the invented light sensor 30, the step of integrating the first integrated signal to generate the second integrated signal includes: Convert the first integrated signal into a second current; and Integrating the second current generates the second integrated signal.

FIG. 3 shows a second embodiment of the high-sensitivity photo sensor of the present invention. The circuit architecture of the photo sensor 50 in FIG. 3 is almost the same as the circuit architecture of the photo sensor 30 in FIG. 1 . The difference is that the photo sensor 50 in FIG. 3 does not have the counter 35 . In FIG. 3 , the circuit structure and/or operation of the photodiode 31 , the reset circuit 32 , the integrator 33 , the comparator 34 , the timer 36 , the reset circuit 37 , the integrator 38 , the comparator 39 , and the counter 40 can be Refer to the description of Figure 1 and no further description will be given here. The difference between the light sensor 50 of FIG. 3 and the light sensor 30 of FIG. 1 is that the timer 36 of FIG. 3 except the time length T between sending the last high level D1_H of the comparison signal D1 and the end of the measurement time Ts. In addition to ', the time length Ti between two adjacent high-level bits D1_H of the comparison signal D1 is also sent, where i is an integer greater than or equal to 1. In addition, every time the comparator 34 sends the comparison signal D1, the timer 36 and the counter 40 respectively send the current time length Ti and the current sensing value O2i to a storage device (not shown) to store the current time length Ti. and the current sensing value O2i. The storage device can be a temporary register or a memory, where the sensing value O2i refers to the sensing value obtained at the i-th time length Ti. For example, as shown in Figure 2, in The sensing value obtained in the first time length T1 is O21, and the sensing value obtained in the fifth time length T5 is O25. After the storage of the current time length Ti and the current sensing value O2i is completed, the time length Ti of the timer 36 and the sensing value O2i of the counter are reset to count again. When the measurement time Ts ends, the timer 36 sends the time length T' between the last high-level D1_H comparison signal D1 and the end of the measurement time Ts to the storage device, and the counter 40 sends the current sensing value O2' to the storage device. storage device. Based on the stored sensing value O2i, sensing value O2', time length Ti and time length T', the sensing value O representing the ambient light (or light) can be calculated . For example, in the embodiment of Figure 2, n=5, so the sensed value .

The light sensor 50 of the present invention can calculate the remaining area 20, so it can obtain more accurate sensing results and has higher sensitivity.

From the above description, it can be understood that the sensing method of the light sensor 50 of the present invention includes the following steps: Use a light sensing element to sense a light at a measurement time to generate a first current; Integrate the first current to generate a first integrated signal; Integrate the first integrated signal to generate a second integrated signal; Generate a sensing value according to the second integrated signal; and The intensity of the light is determined based on the sensed value.

In FIG. 1 and FIG. 3 , the reset circuits 32 and 37 are implemented as switched capacitor circuits, but the present invention is not limited thereto. FIG. 4 shows another embodiment of the reset circuits 32 and 37 in FIG. 1 and FIG. 3 . In FIG. 4 , the reset circuit 32 includes a current source 321 and a reset switch SW15 . The reset switch SW15 is coupled between the current source 321 and the integrator 33 . Specifically, the reset switch SW15 is coupled between the current source 321 and the inverting input terminal of the operational amplifier 331 of the integrator 33 . The reset switch SW15 is controlled by the comparison signal D1. When the comparison signal D1 is at the high level D1_H, the reset switch SW15 is closed, so that the current source 321 provides a reset current If1 to reset the integration signal Pout. The reset circuit 37 of FIG. 4 includes a current source 371 and a reset switch SW16. The reset switch SW16 is coupled between the current source 371 and the integrator 38. Specifically, the reset switch SW16 is coupled between the current source 371 and the inverting input terminal of the operational amplifier 382 of the integrator 38 . Reset switch SW16 is controlled by comparison signal D2. When the comparison signal D2 is at the high level D2_H, the reset switch SW16 is closed, so that the current source 371 provides a reset current If2 to reset the integration signal Aout.

The above are only embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed in the embodiments above, they are not used to limit the present invention. Anyone with ordinary knowledge in the technical field, Without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

20: Survival area 30:Light sensor 31: Photodiode 32:Reset circuit 321:Current source 33: Integrator 331: Operational amplifier 34: Comparator 35: Counter 36: timer 37:Reset circuit 371:Current source 38:Integrator 381:Impedance circuit 382: Operational amplifier 39: Comparator 40: Counter 50:Light sensor

Figure 1 shows a first embodiment of a high-sensitivity photo sensor of the present invention. FIG. 2 shows the waveforms of the integrated signal Pout and the comparison signal D1 in FIG. 1 at the measurement time Ts. FIG. 3 shows a second embodiment of the high-sensitivity photo sensor of the present invention. FIG. 4 shows another embodiment of the reset circuit of FIG. 1 and FIG. 3 .

30:Light sensor

31: Photodiode

32:Reset circuit

33: Integrator

331: Operational amplifier

34: Comparator

35:Counter

36: timer

37:Reset circuit

38:Integrator

381:Impedance circuit

382: Operational amplifier

39: Comparator

40: Counter

Claims (21)

A high-sensitivity light sensor including: a light sensing element for sensing a light at a measurement time and generating a first current; a first integrator, coupled to the light sensing element, integrating the first current to generate a first integrated signal; a first comparator, coupled to the first integrator, for comparing the first integrated signal with a critical value to generate a first comparison signal. When the first integrated signal is greater than the critical value, the first comparison signal The signal is the first level; a first reset circuit coupled to the first integrator and the first comparator for resetting the first integration signal when the first comparison signal is at the first level; a first counter, coupled to the first comparator, used to count the number of times the comparison signal reaches the first level and generate a first sensing value; a second integrator, coupled to the first integrator, integrating the first integrated signal to generate a second integrated signal; A second comparator, coupled to the second integrator, is used to compare the second integrated signal with the critical value to generate a second comparison signal. When the second integrated signal is greater than the critical value, the second comparator The comparison signal is a second level; a second reset circuit coupled to the second integrator and the second comparator for resetting the second integration signal when the second comparison signal is at the second level; and a second counter, coupled to the second comparator, used to count the number of times the comparison signal reaches the second level and generate a second sensing value; Wherein, when the first comparison signal is at the first level, the second counter is reset; When the measurement time ends, the first sensing value and the second sensing value are used to determine the intensity of the light. The light sensor of claim 1, wherein the first integrator includes: An operational amplifier has an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the light sensing element, the non-inverting input terminal is coupled to a ground terminal, and the output terminal coupled to the first comparator; a capacitor coupled between the inverting input terminal and the output terminal; and A switch is connected in parallel with the capacitor; Wherein, when the measurement time starts, the switch is opened, and when the measurement time ends, the switch is closed. The light sensor of claim 1, wherein the second integrator includes: An operational amplifier having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the non-inverting input terminal is coupled to a ground terminal, and the output terminal is coupled to the second comparator; An impedance circuit coupled between the inverting input terminal and the first integrator for converting the first integrated signal into a current signal; a capacitor coupled between the inverting input terminal and the output terminal; and A switch is connected in parallel with the capacitor and is closed because the first comparison signal is at the first level. The light sensor of claim 3, wherein the impedance circuit is a switched capacitor circuit. The light sensor of claim 1 further includes a timer coupled to the first comparator for calculating the time between the last first level of the first comparison signal and the end of the measurement time. A length of time, wherein the length of time, the first sensing value and the second sensing value are used to calculate the intensity of the light. The light sensor as described in claim 5, wherein the intensity of the light is , where O1 is the first sensing value, O2 is the second sensing value, and T' is the time length. The light sensor of claim 1, wherein the first reset circuit includes: a current source; and A reset switch coupled between the current source and the first integrator is closed in response to the first comparison signal being at the first level; Wherein, when the reset switch is closed, the current source provides a reset current to reset the first integrated signal. The light sensor of claim 1, wherein the second reset circuit includes: a current source; and a reset switch coupled between the current source and the second integrator and closed in response to the second comparison signal being at the second level; Wherein, when the reset switch is closed, the current source provides a reset current to reset the second integrated signal. The light sensor of claim 1, wherein the first reset circuit includes: a voltage source; and A switched capacitor circuit is coupled between the voltage source and the first integrator, and provides a reset current to reset the first integration signal when the first comparison signal is at the first level. The light sensor of claim 1, wherein the second reset circuit includes: a voltage source; and A switched capacitor circuit is coupled between the voltage source and the second integrator, and provides a reset current to reset the second integration signal when the second comparison signal is at the second level. A high-sensitivity light sensor including: a light sensing element for sensing a light at a measurement time and generating a first current; a first integrator, coupled to the light sensing element, integrating the first current to generate a first integrated signal; a first comparator, coupled to the first integrator, for comparing the first integrated signal with a critical value to generate a first comparison signal. When the first integrated signal is greater than the critical value, the first comparison signal The signal is a first level; a timer, coupled to the first comparator, for calculating a first time length between two adjacent first levels of the first comparison signal after the measurement time starts, and calculating the a second length of time between the last first level of the first comparison signal and the end of the measurement time; a first reset circuit coupled to the first integrator and the first comparator for resetting the first integration signal when the first comparison signal is at the first level; a second integrator, coupled to the first integrator, integrating the first integrated signal to generate a second integrated signal; A second comparator, coupled to the second integrator, is used to compare the second integrated signal with the critical value to generate a second comparison signal. When the second integrated signal is greater than the critical value, the second comparator The comparison signal is a second level; a second reset circuit coupled to the second integrator and the second comparator for resetting the second integration signal when the second comparison signal is at the second level; and a counter, coupled to the second comparator, used to count the number of times the second comparison signal reaches the second level and generate a sensing value; Wherein, when the first comparison signal is the first level, the light sensor stores the sensing value and resets the second counter; When the measurement time ends, all the stored sensing values and the current sensing value are used to determine the intensity of the light. The light sensor of claim 11, wherein the first integrator includes: An operational amplifier has an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the light sensing element, the non-inverting input terminal is coupled to a ground terminal, and the output terminal coupled to the first comparator; a capacitor coupled between the inverting input terminal and the output terminal; and A switch is connected in parallel with the capacitor; Wherein, when the measurement time starts, the switch is opened, and when the measurement time ends, the switch is closed. The light sensor of claim 11, wherein the second integrator includes: An operational amplifier having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the non-inverting input terminal is coupled to a ground terminal, and the output terminal is coupled to the second comparator; An impedance circuit coupled between the inverting input terminal and the first integrator for converting the first integrated signal into a current signal; a capacitor coupled between the inverting input terminal and the output terminal; and A switch is connected in parallel with the capacitor and is closed because the first comparison signal is at the first level. The light sensor of claim 13, wherein the impedance circuit is a switched capacitor circuit. The light sensor as claimed in claim 11, wherein the intensity of the light is , where T' is the second time length, O2' is the sensing value obtained during the second time length T', n is a positive integer, and Ti is the i-1th first level to the i-th The first time length between the first levels, O2i is the sensing value obtained at the i-th first time length Ti, and i is an integer greater than or equal to 1. The light sensor of claim 11, wherein the first reset circuit includes: a current source; and A reset switch coupled between the current source and the first integrator is closed in response to the first comparison signal being at the first level; Wherein, when the reset switch is closed, the current source provides a reset current to reset the first integrated signal. The light sensor of claim 11, wherein the second reset circuit includes: a current source; and a reset switch coupled between the current source and the second integrator and closed in response to the second comparison signal being at the second level; Wherein, when the reset switch is closed, the current source provides a reset current to reset the second integrated signal. The light sensor of claim 11, wherein the first reset circuit includes: a voltage source; and A switched capacitor circuit is coupled between the voltage source and the first integrator, and provides a reset current to reset the first integration signal when the first comparison signal is at the first level. The light sensor of claim 11, wherein the second reset circuit includes: a voltage source; and A switched capacitor circuit is coupled between the voltage source and the second integrator, and provides a reset current to reset the second integration signal when the second comparison signal is at the second level. A high-sensitivity light sensor sensing method includes the following steps: Use a light sensing element to sense a light at a measurement time to generate a first current; Integrate the first current to generate a first integrated signal; Convert the first integrated signal into a first sensing value; Integrate the first integrated signal to generate a second integrated signal; Generate a second sensing value according to the second integrated signal; and The intensity of the light is determined based on the first sensing value and the second sensing value. A high-sensitivity light sensor sensing method includes the following steps: Use a light sensing element to sense a light at a measurement time to generate a first current; Integrate the first current to generate a first integrated signal; Integrate the first integrated signal to generate a second integrated signal; Generate a sensing value according to the second integrated signal; and The intensity of the light is determined based on the sensed value.