High-sensitivity light sensor and sensing method thereof

Abstract

The present invention discloses a highly sensitive light sensor and a sensing method thereof, wherein the light sensor includes a light sensing element, a first integrator, a comparator, and a second integrator. The light sensing element senses light during a measurement period and generates a current. The first integrator integrates the current to generate a first integrated signal. The comparator compares the first integrated signal with a threshold value to generate a comparison signal. When the first integrated signal is greater than the threshold value, the comparison signal is at a first level. The second integrator is coupled to the first integrator and integrates the first integrated signal to generate a second integrated signal. The light sensor of the present invention uses two integrators to perform a second integration of the sensed current, resulting in higher sensitivity.

Description

Technical Field

[0001] The present invention relates to a light sensor, and more particularly to a light sensor for sensing ambient light and a sensing method thereof. Background Art

[0002] Light sensors can be used to sense ambient light and determine its intensity. Traditional ambient light sensors use a photodiode to sense ambient light, generating a current. This current is then converted to a digital value by an analog-to-digital converter to determine light intensity. However, the ambient light intensity calculated by conventional ambient light sensors may differ from the actual ambient light intensity. Recently, many electronic devices have increasingly demanded higher sensitivity from light sensors, and traditional ambient light sensors no longer meet these requirements. Therefore, a highly sensitive light sensor is desired. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-sensitivity light sensor and a sensing method thereof.

[0004] The present invention provides a high-sensitivity photosensor, comprising a photosensor element, a first integrator, a first comparator, a first reset circuit, a first counter, a second integrator, a second comparator, a second reset circuit, and a second counter. The photosensor element senses light during a measurement period and generates a first current. The first integrator is coupled to the photosensor element and integrates the first current to generate a first integrated signal. The first comparator is coupled to the first integrator and compares the first integrated signal with a threshold value to generate a first comparison signal. When the first integrated signal is greater than the threshold value, the first comparison signal is at a first level. The first reset circuit is coupled to the first integrator and the first comparator and resets the first integrated signal when the first comparison signal is at the first level. The first counter is coupled to the first comparator and counts the number of times the first comparison signal is at the first level to generate a first sensing value. The second integrator is coupled to the first integrator and integrates the first integrated signal to generate a second integrated signal. The second comparator is coupled to the second integrator and is configured 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 is at a second level. The second reset circuit is coupled to the second integrator and the second comparator and is configured to reset the second integrated signal when the second comparison signal is at the second level. The second counter is coupled to the second comparator and is configured to count the number of times the second comparison signal is at the second level to generate a second sensing value. The second counter is reset when the first comparison signal is at the first level. When the measurement time expires, the first sensing value and the second sensing value are used to determine the intensity of the light.

[0005] The present invention also provides a high-sensitivity photosensor, comprising a photosensor element, a first integrator, a first comparator, a timer, a first reset circuit, a second integrator, a second comparator, a second reset circuit, and a counter. The photosensor element senses light during a measurement period and generates a first current. The first integrator is coupled to the photosensor element and is configured to integrate the first current to generate a first integrated signal. The first comparator is coupled to the first integrator and is configured to compare the first integrated signal with a threshold value to generate a first comparison signal. When the first integrated signal is greater than the threshold value, the first comparison signal is at a first level. The timer is coupled to the first comparator and is configured to calculate a first time length between two adjacent first levels of the first comparison signal after the measurement period begins, and to calculate a second time length between the last first level of the first comparison signal and the end of the measurement period. The first reset circuit is coupled to the first integrator and the first comparator and is configured to reset the first integrated signal when the first comparison signal is at the first level. The second integrator is coupled to the first integrator and is configured to integrate the first integrated signal to generate a second integrated signal. The second comparator is coupled to the second integrator and is configured to compare the second integrated signal with the threshold value to generate a second comparison signal. When the second integrated signal is greater than the threshold value, the second comparison signal is at a second level. The second reset circuit is coupled to the second integrator and the second comparator and is configured to reset the second integrated signal when the second comparison signal is at the second level. The counter is coupled to the second comparator and is configured to count the number of times the second comparison signal is at the second level to generate a sensing value. When the first comparison signal is at the first level, the light sensor stores the sensing value and resets the second counter. When the measurement time expires, all stored sensing values ​​and the current sensing value are used to determine the intensity of the light.

[0006] The present invention also provides a sensing method for a high-sensitivity light sensor, comprising the following steps: using a light sensing element to sense 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 based on the second integrated signal; and determining the intensity of the light based on the first and second sensing values.

[0007] The present invention also provides a sensing method for a high-sensitivity light sensor, comprising the following steps: using a light sensing element to sense 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.

[0008] The optical sensor and sensing method thereof of the present invention can obtain more accurate sensing results and have higher sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A first embodiment of the high-sensitivity photosensor of the present invention is shown.

[0010] Figure 2 show Figure 1 FIG. 4 is a waveform diagram of the integrated signal Pout and the comparison signal D1 at the measurement time Ts.

[0011] Figure 3 A second embodiment of the high-sensitivity photosensor of the present invention is shown.

[0012] Figure 4 show Figure 1 and Figure 3 Another embodiment of the reset circuit.

[0013] Explanation of the reference numerals: 20-residual 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. DETAILED DESCRIPTION

[0014] Figure 1 A first embodiment of the high-sensitivity photosensor of the present invention is shown. Figure 2 show Figure 1 FIG. 4 is a waveform diagram of the integrated signal Pout and the comparison signal D1 at the measurement time Ts. Figure 1The light sensor 30 includes a light sensing element (e.g., a photodiode 31), a reset circuit 32, an integrator 33, a comparator 34, a counter 35, a timer 36, a reset circuit 37, an integrator 38, a comparator 39, and a counter 40. The photodiode 31 senses ambient light or a light source 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 of the operational amplifier 331 is connected to the photodiode 31, the non-inverting input of the operational amplifier 331 is connected to ground GND, and the output of the operational amplifier 331 is connected to the non-inverting input of the comparator 34. The capacitor CF1 is connected between the inverting input and output 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, signal Pr is provided by a circuit control unit (not shown). During measurement time Ts, signal Pr controls switch SW13 to be turned on (off). When signal Pr controls switch SW13 to be closed (on), integrator 33 enters a reset state, at which point integrated signal Pout is reset to a starting value, and integrator 33 stops integrating current Ip'. When signal Pr controls switch SW13 to be turned off (off), integrator 33 exits the reset state and begins integrating current Ip', causing integrated signal Pout to rise. Comparator 34 is connected to integrator 33. Comparator 34 compares integrated signal Pout output by integrator 33 with a reference voltage Vref serving as a threshold. When integrated signal Pout is greater than reference voltage Vref, comparison signal D1 output by comparator 34 becomes a high level (i.e., a first level) D1_H, but the present invention is not limited thereto. Reset circuit 32 is connected to integrator 33 and comparator 34. The reset circuit 32 resets the integrated signal Pout back to the starting value when the comparison signal D1 is at a high level D1_H. The reset circuit 32 includes a voltage source (not shown) and a switched capacitor (switch-C) circuit, wherein the voltage source can 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, wherein the switch SW1 is connected between the first end of the capacitor C1 and the photodiode 31, the switch SW2 is connected between the second end of the capacitor C1 and the voltage source (Vref), the switch SW3 is connected between the second end of the capacitor C1 and the ground terminal GND, and the switch SW4 is connected between the first end 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 The signal is the inverted signal of the comparison signal D1. When the comparison signal D1 is at a high level D1_H, Figure 2 As shown, switches SW1 and SW2 are closed and switches SW3 and SW4 are opened. At this time, the reset circuit 32 is activated to generate a reset current. The integrated signal Pout is reset to the initial value, where t1 is the duration of the closing of switches SW1 and SW2. The counter 35 counts the number of times the comparison signal D1 is at a high level within the measurement time Ts to generate a sensing value O1.

[0015] The reset circuit 32, integrator 33, comparator 34, and counter 35 can be considered an analog-to-digital converter for converting the analog current Ip' into a digital sensed value O1. The timer 36 is connected to the output 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 length T' between the last high level D1_H and the end of the measurement time Ts according to the clock signal CK. Ti refers to the time length between the i-1th high level D1_H and the i-th high level D1_H of the comparison signal D1. For example, Figure 2 As shown, 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 time length between the 1st high level D1_H and the 2nd high level D1_H. Figure 1 In the embodiment of the present invention, the timer 36 outputs the time length T' at the end of the measured time Ts.

[0016] like Figure 1 As shown, the integrator 38 is connected to the output terminal of the operational amplifier 331 in the integrator 33, and is used to integrate the integrated signal Pout to generate the integrated 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, ​​and is used to convert 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, wherein the switch SW5 is connected between the first end of the capacitor C2 and the integrator 33, the switch SW6 is connected between the second end of the capacitor C2 and the inverting input terminal of the operational amplifier 382, ​​the switch SW7 is connected between the second end of the capacitor C2 and the ground terminal GND, and the switch SW8 is connected between the first end of the capacitor C2 and the ground terminal GND. The switches SW5 and SW6 are controlled by the clock signal CK, while the switches SW7 and SW8 are controlled by the clock signal that is inverse to the clock signal CK. When switches SW5 and SW6 are open (off) and switches SW7 and SW8 are closed (on), the charge on capacitor C2 is cleared. When switches SW5 and SW6 are closed and switches SW7 and SW8 are open, capacitor C2 generates a current signal. Where t2 is the time length of SW5 and SW6 being closed. The equivalent resistance R of the impedance circuit 381 is exist Figure 1 In the embodiment, impedance circuit 381 is a switched capacitor circuit, but the present invention is not limited thereto. The non-inverting input of operational amplifier 382 is connected to ground GND, and the output of operational amplifier 382 is connected to the non-inverting input of comparator 39. Capacitor CF2 is connected between the inverting input and output of operational amplifier 382. Switch SW14 is connected in parallel with capacitor CF2 and is controlled by comparison signal D1. When comparison signal D1 is at a high level D1_H, switch SW14 is closed (on), integrator 38 enters a reset state, at which point integrated signal Aout is reset to a starting value, and integrator 38 stops integrating integrated signal Pout. When comparison signal D1 is at a low level D1_L, switch SW14 is opened (off), integrator 38 exits the reset state and begins integrating integrated signal Pout, causing integrated signal Aout to rise.

[0017] Figure 1 Comparator 39 is connected to integrator 38. Comparator 39 is used to compare the integrated signal Aout output by integrator 38 with a reference voltage Vref. When the integrated signal Aout is greater than the reference voltage Vref, the comparison signal D2 generated by comparator 39 is at a high level (i.e., a second level) D2_H (not shown), but the present invention is not limited to this. Reset circuit 37 is connected to integrator 38 and comparator 39. When the comparison signal D2 is at a high level D2_H, reset circuit 37 resets integrated signal Aout to an initial value. Reset circuit 37 includes a voltage source (not shown) and a switched capacitor circuit, wherein the voltage source can be a voltage source that provides reference voltage Vref. The switched capacitor circuit includes a capacitor C3 and four switches SW9, SW10, SW11, and SW12, wherein switch SW9 is connected between the first end of capacitor C3 and the voltage source, switch SW10 is connected between the second end of capacitor C3 and the inverting input of operational amplifier 382, ​​switch SW11 is connected between the second end of capacitor C3 and ground GND, and switch SW12 is connected between the first end of capacitor C3 and ground GND. Switches SW9 and SW10 are controlled by comparison signal D2, and switches SW11 and SW12 are controlled by signal D2, wherein signal D2 is an inverted signal of comparison signal D2. When comparison signal D2 is at a high level, switches SW9 and SW10 are closed and switches SW11 and SW12 are opened, at which time reset circuit 37 generates a reset current. The integrated signal Aout is reset to its initial value, where t3 is the duration of time that switches SW9 and SW10 are closed. Counter 40 is connected to comparators 34 and 39 and counts the number of times comparison signal D2 reaches a high level D2_H to generate a sensed value O2. When comparison signal D1 from comparator 34 reaches a high level D1_H, counter 40 is reset, returning sensed value O2 to 0. Reset circuit 37, integrator 38, comparator 39, and counter 40 can be considered an analog-to-digital converter.

[0018] At the end of the measurement time Ts, the sensing value representing the ambient light (or light intensity) can be calculated based on the sensing value O1 and the sensing value O2. Since the optical sensor 30 of the present invention can further calculate the residual area 20 , a more accurate sensing result can be obtained with higher sensitivity.

[0019] From the above description, it can be understood that the sensing method of the optical sensor 30 of the present invention includes the following steps:

[0020] Using a light sensing element to sense light during a measurement time to generate a first current;

[0021] integrating the first current to generate a first integrated signal;

[0022] converting the first integrated signal into a first sensing value;

[0023] integrating the first integrated signal to generate a second integrated signal;

[0024] Generate a second sensing value according to the second integrated signal; and

[0025] The intensity of the light is determined according to the first sensing value and the second sensing value.

[0026] In the sensing method of the invented optical sensor 30, the step of integrating the first integrated signal to generate the second integrated signal includes:

[0027] converting the first integrated signal into a second current; and

[0028] Integrating the second current generates the second integrated signal.

[0029] Figure 3 A second embodiment of the high-sensitivity photosensor of the present invention is shown. Figure 3 The circuit architecture of the light sensor 50 is Figure 1 The circuit architecture of the optical sensor 30 is almost the same, the difference is that Figure 3 The light sensor 50 does not have a counter 35. Figure 3The 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 referred to. Figure 1 The description is not repeated here. Figure 3 The light sensor 50 and Figure 1 The difference of the light sensor 30 is that, Figure 3 In addition to sending out the time length T' between the last high level D1_H of the comparison signal D1 and the end of the measurement time Ts, the timer 36 also sends out the time length Ti between two adjacent high level D1_H of the comparison signal D1, where i is an integer greater than or equal to 1. In addition, each time the comparator 34 sends out the comparison signal D1, the timer 36 and the counter 40 respectively send out 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 register or a memory, where the sensing value O2i refers to the sensing value obtained during the i-th time length Ti. For example, Figure 2 As shown, the sensing value obtained at the first time length T1 is O21, and the sensing value obtained at the fifth time length T5 is O25. After the current time length Ti and the current sensing value O2i are stored, the time length Ti of the timer 36 and the sensing value O2i of the counter are reset to restart the counting. 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. Based on the stored sensing value O2i, sensing value O2', time length Ti and time length T', the sensing value representing the ambient light (or light) can be calculated. For example, in Figure 2 In the embodiment, n=5, so the sensing value

[0030]

[0031] The optical sensor 50 of the present invention can calculate the residual area 20, thereby obtaining a more accurate sensing result and having a higher sensitivity.

[0032] From the above description, it can be understood that the sensing method of the optical sensor 50 of the present invention includes the following steps:

[0033] Using a light sensing element to sense light during a measurement time to generate a first current;

[0034] integrating the first current to generate a first integrated signal;

[0035] integrating the first integrated signal to generate a second integrated signal;

[0036] Generating a sensing value according to the second integrated signal; and

[0037] The intensity of the light is determined according to the sensed value.

[0038] exist Figure 1 and Figure 3 In the embodiment, the reset circuits 32 and 37 are implemented by switched capacitor circuits, but the present invention is not limited thereto. Figure 4 show Figure 1 and Figure 3 Another embodiment of the reset circuits 32 and 37. Figure 4 In the embodiment, 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 a high level D1_H, the reset switch SW15 is closed, causing the current source 321 to provide a reset current If1 to reset the integrated signal Pout. Figure 4 The reset circuit 37 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. The reset switch SW16 is controlled by the comparison signal D2. When the comparison signal D2 is at a high level D2_H, the reset switch SW16 is closed, causing the current source 371 to provide a reset current If2 to reset the integrated signal Aout.

[0039] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been provided as an embodiment, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-sensitivity optical sensor, characterized in that: include: a light sensing element for sensing light during a measurement period to generate 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 threshold value to generate a first comparison signal, wherein when the first integrated signal is greater than the threshold value, the first comparison signal is at a first level; a first reset circuit coupled to the first integrator and the first comparator, for resetting the first integrated signal when the first comparison signal is at the first level; a first counter coupled to the first comparator, for counting the number of times the comparison signal is at the first level to 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 and configured to compare the second integrated signal with the threshold value to generate a second comparison signal. When the second integrated signal is greater than the threshold value, the second comparison signal is at a second level; a second reset circuit coupled to the second integrator and the second comparator, for resetting the second integrated signal when the second comparison signal is at the second level; as well as a second counter coupled to the second comparator, for counting the number of times the comparison signal is at the second level to generate a second sensing value; When the first comparison signal is at the first level, the second counter is reset; When the measuring time ends, the first sensing value and the second sensing value are used to determine the intensity of the light.

2. The optical sensor according to claim 1, wherein The first integrator comprises: an operational amplifier having 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 is coupled to the first comparator; a capacitor coupled between the inverting input terminal and the output terminal; and a switch connected in parallel with the capacitor; When the measurement time starts, the switch is opened, and when the measurement time ends, the switch is closed.

3. The optical sensor according to claim 1, wherein The second integrator comprises: 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 in response to the first comparison signal being at the first level.

4. The optical sensor according to claim 3, wherein The impedance circuit is a switched capacitor circuit.

5. The optical sensor according to claim 1, wherein A timer is also included, coupled to the first comparator, for calculating the time length from the last first level of the first comparison signal to the end of the measurement time, wherein the time length, the first sensing value, and the second sensing value are used to calculate the intensity of the light.

6. The optical sensor according to claim 5, wherein The intensity of this light is Wherein O1 is the first sensing value, O2 is the second sensing value, and T' is the time length.

7. The optical sensor according to claim 1, wherein The first reset circuit includes: a current source; and a reset switch coupled between the current source and the first integrator, and closed in response to the first comparison signal being at the first level; When the reset switch is closed, the current source provides a reset current to reset the first integrated signal.

8. The optical sensor according to 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; When the reset switch is closed, the current source provides a reset current to reset the second integrated signal.

9. The optical sensor according to 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 integrated signal when the first comparison signal is at the first level.

10. The optical sensor according to 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 integrated signal when the second comparison signal is at the second level.

11. A high-sensitivity optical sensor, characterized in that: include: a light sensing element for sensing light during a measurement period to generate 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 and configured to compare the first integrated signal with a threshold value to generate a first comparison signal. When the first integrated signal is greater than the threshold value, the first comparison signal is at a first level; a timer coupled to the first comparator, configured to calculate, after the measurement time begins, a first time length between two adjacent first levels of the first comparison signal, and a second time length 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 integrated 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 and configured to compare the second integrated signal with the threshold value to generate a second comparison signal. When the second integrated signal is greater than the threshold value, the second comparison signal is at a second level; a second reset circuit coupled to the second integrator and the second comparator, for resetting the second integrated signal when the second comparison signal is at the second level; as well as a counter coupled to the second comparator, for counting the number of times the second comparison signal is at the second level to generate a sensing value; When the first comparison signal is at the first level, the light sensor stores the sensed value and resets the counter; When the measuring time ends, all the stored sensing values ​​and the current sensing value are used to determine the intensity of the light.

12. The optical sensor according to claim 11, wherein The first integrator comprises: an operational amplifier having 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 is coupled to the first comparator; a capacitor coupled between the inverting input terminal and the output terminal; and a switch connected in parallel with the capacitor; When the measurement time starts, the switch is opened, and when the measurement time ends, the switch is closed.

13. The optical sensor according to claim 11, wherein The second integrator comprises: 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 in response to the first comparison signal being at the first level.

14. The optical sensor according to claim 13, wherein The impedance circuit is a switched capacitor circuit.

15. The optical sensor according to claim 11, wherein The intensity of this light is Wherein T' is the second time length, O2' is the sensing value obtained in the second time length T', n is a positive integer, Ti is the first time length between the i-1th first level and the i-th first level, O2i is the sensing value obtained in the i-th first time length Ti, and i is an integer greater than or equal to 1.

16. The optical sensor according to claim 11, wherein The first reset circuit includes: a current source; and a reset switch coupled between the current source and the first integrator, and closed in response to the first comparison signal being at the first level; When the reset switch is closed, the current source provides a reset current to reset the first integrated signal.

17. The light sensor according to 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; When the reset switch is closed, the current source provides a reset current to reset the second integrated signal.

18. The light sensor according to 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 integrated signal when the first comparison signal is at the first level.

19. The light sensor according to 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 integrated signal when the second comparison signal is at the second level.

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