CN111508411A - light sensing circuit - Google Patents

Abstract

A photo sensing circuit includes first, second and third photo transistors, first and second capacitors and first and second switching elements. The first, second and third photo transistors are used for sensing the first, second and third color lights respectively. The first switch element is coupled to the first capacitor and is used for outputting a sampling signal. The second switch element is coupled between the first photo transistor and the first capacitor. The first photo transistor is coupled to the second photo transistor, the third photo transistor and the second capacitor. The first photo transistor, the second photo transistor and the third photo transistor are used for receiving a first sensing signal. The third photo transistor and the first capacitor are used for receiving the first voltage. The second capacitor is used for receiving a second sensing signal.

Description

light sensing circuit

technical field

The present disclosure relates to a sensing circuit, and in particular, to a light sensing circuit.

Background technique

With the rapid development of panel technology, the resolution of the panel also increases rapidly. Therefore, the area of each pixel in the panel is getting smaller and smaller, and in order to maintain the same function, the density of the electronic components in the pixel is also becoming more and more critical.

SUMMARY OF THE INVENTION

An embodiment of the present disclosure relates to a light-sensing circuit, which includes a first light-sensing transistor, a second light-sensing transistor, a third light-sensing transistor, a first capacitor, a second capacitor, a first switching element, and a second switching element. The first phototransistor includes a first terminal, a second terminal and a control terminal, and the first phototransistor is used for sensing the first color light. The second phototransistor includes a first end, a second end and a control end, and the second phototransistor is used for sensing the second color light. The third phototransistor includes a first terminal, a second terminal and a control terminal, and the third phototransistor is used for sensing the third color light. The first capacitor includes a first end and a second end. The second capacitor includes a first terminal and a second terminal. The first switch element is coupled to the first end of the first capacitor for outputting the sampling signal. The second switch element is coupled between the first end of the first phototransistor and the first end of the first capacitor. The second end of the first phototransistor is coupled to the first end of the second phototransistor, the first end of the third phototransistor and the second end of the second capacitor. The control terminal of the first phototransistor, the control terminal of the second phototransistor, the second terminal of the second phototransistor, and the control terminal of the third phototransistor are used for receiving the first sensing signal. The second terminal of the third phototransistor and the second terminal of the first capacitor are used for receiving the first voltage. The first end of the second capacitor is used for receiving the second sensing signal.

To sum up, the light sensing circuits provided by some embodiments of the present disclosure can sense different combinations of color light under the structure of the same sensing circuit. In this way, it is possible to avoid the problem of sensing different combinations of color light, requiring individual corresponding circuits, and greatly increasing the circuit area.

Description of drawings

A more complete understanding of the present disclosure can be obtained by reading the following detailed description of the embodiments, with reference to the accompanying drawings as follows:

FIG. 1 is a schematic diagram of a sensing system according to some embodiments of the present disclosure;

2 is a schematic diagram of a light sensing circuit according to some embodiments of the present disclosure;

FIG. 3 is a signal waveform diagram illustrating an operation mode of the light sensing circuit in FIG. 2 in one frame according to some embodiments of the present disclosure;

FIG. 4 is a schematic diagram of a light sensing circuit according to some embodiments of the present disclosure and a signal waveform diagram shown in FIG. 3;

FIGS. 5A and 5B are schematic diagrams of the light sensing circuit shown in accordance with some embodiments of the present disclosure and the signal waveform shown in FIG. 3 ;

FIG. 6 is a schematic diagram of the light sensing circuit shown in accordance with some embodiments of the present disclosure and the signal waveform shown in FIG. 3;

FIGS. 7A and 7B are schematic diagrams of the light sensing circuit shown in accordance with some embodiments of the present disclosure and the signal waveform shown in FIG. 3 ;

FIG. 8 is a schematic diagram of the light sensing circuit shown in accordance with some embodiments of the present disclosure and the signal waveform shown in FIG. 3;

FIG. 9 is a waveform diagram of a scan operation according to some embodiments of the present disclosure;

10 is a schematic diagram of a light sensing circuit according to other embodiments of the present disclosure;

FIG. 11 is a signal waveform diagram illustrating the operation of the light sensing circuit in FIG. 10 according to other embodiments of the present disclosure;

12 is a schematic diagram of a pixel layout according to some embodiments of the present disclosure;

13 is a schematic diagram of a light sensing circuit according to other embodiments of the present disclosure; and

FIG. 14 is a signal waveform diagram illustrating the operation mode of the light sensing circuit in FIG. 13 in one frame according to other embodiments of the present disclosure.

Description of reference numbers:

100 Sensing Systems

110 pixel array

120 timing control circuit

130 Processing Circuits

140 drive circuit

150 Driver circuit

160 drive circuit

200 light sensing circuit

M1 phototransistor

M2 phototransistor

M3 phototransistor

CF1 color filter

CF2 filter

CF3 filter

Tsw1 switching element

Tsw2 switching element

C1 Capacitor

C2 Capacitor

Sn1 sensing signal

Sn2 sensing signal

VSH voltage

Sout sampling signal

Gsw1 control signal

Gsw2 control signal

SF1 first subframe

SF2 second subframe

Iini1 first initialization operation

Iini2 second initialization operation

Isen1 first sensing operation

Isen2 second sensing operation

Isam1 first sampling operation

Isam2 second sampling operation

t time

P1 path

P2 path

P3 path

P4 path

P5 path

P6 path

P7 path

L light source

Gswn+1 control signal

Gswn+2 control signal

Gswn+3 control signal

Gswn+4 control signal

Gswn+x control signal

Tsw3 switching element

Tsw4 switching element

Gn control signal

VDD voltage

Ss output signal

210 Output circuit

1200A pixel layout

1200B pixel layout

1200C pixel layout

M1a phototransistor

M1b phototransistor

M2a phototransistor

M2b phototransistor

M3a phototransistor

M3b phototransistor

PI pixel

SPI Subpixel

300 Light Sensing Circuit

M4 phototransistor

M5 phototransistor

M6 phototransistor

M7 phototransistor

M8 phototransistor

M9 phototransistor

CF4 color filter

CF5 color filter

CF6 color filter

CF7 filter

CF8 filter

CF9 filter

Tsw5 switching element

Tsw6 switching element

Tsw7 switching element

Gsw5 control signal

Gsw6 control signal

Gsw7 control signal

C3 Capacitor

C4 Capacitor

Sn3 sensing signal

Sn4 sensing signal

VSL voltage

Detailed ways

The following is a detailed description of the embodiments in conjunction with the accompanying drawings, but the specific embodiments described are only used to explain the embodiments of the present disclosure, and are not used to limit the embodiments of the present disclosure, and the description of the structure and operation is not used to limit its implementation. Sequence, any structure recombined by elements, resulting in a device with equal technical effect, are all within the scope of the disclosure of the embodiments of the present disclosure.

As used herein, "coupling" or "connection" may refer to two or more elements in direct physical or electrical contact with each other, or in indirect physical or electrical contact with each other, and may also refer to two or more elements Elements interact or act on each other.

Refer to Figure 1. FIG. 1 is a schematic diagram of a sensing system 100 according to some embodiments of the present disclosure. As shown in FIG. 1 , the sensing system 100 includes a pixel array 110 , a timing control circuit 120 , a processing circuit 130 , a driving circuit 140 , a driving circuit 150 and a driving circuit 160 . The pixel array 110 is coupled to the timing control circuit 120 , the processing circuit 130 , the driving circuit 140 , the driving circuit 150 and the driving circuit 160 . The timing control circuit 120 is coupled to the processing circuit 130 , the driving circuit 140 , the driving circuit 150 and the driving circuit 160 . The processing circuit 130 is coupled to the driving circuit 150 .

In some embodiments, the pixel array 110 is composed of a plurality of pixels (not shown) for sensing light signals. In other embodiments, the pixel array 110 is further used for display.

Each pixel in the pixel array 110 includes a light sensing circuit 200 (shown in FIG. 2 ) for sensing light impinging on the pixel. Other contents of the light sensing circuit 200 will be discussed later in conjunction with FIGS. 2 to 14 .

In some embodiments, the pixel array 110 is controlled by the driving circuit 140 for transmitting the sensing signal Sn1 , the sensing signal Sn2 , the control signal Gsw1 , the control signal Gsw2 and the control signal Gn to the pixel array 110 . The pixel array 110 senses light according to the sensing signal Sn1 and the sensing signal Sn2 , and generates an output signal Ss to the processing circuit 130 according to the control signal Gsw1 , the control signal Gsw2 and the control signal Gn.

In some embodiments, the timing control circuit 120 is used to control the driving circuit 140 so that the driving circuit 140 can drive the pixel array 110 to sense light. The timing control circuit 120 is also used for transmitting the voltage VSH and the voltage VSL to the pixel array 110 . In some embodiments, the voltage VSH and the voltage VSL are voltage reference levels when the pixel array 110 operates, the voltage VSH is the system high level, and the voltage VSL is the system low level.

In some embodiments, the timing control circuit 120 is further configured to synchronize the processing circuit 130 so that the processing circuit 130 can process the received output signal Ss according to the timing.

In some other embodiments, the timing control circuit 120 is used to control the driving circuit 150 and the driving circuit 160 . The driving circuit 150 is used for transmitting the gate driving signal to the pixel array 100, and the driving circuit 160 is used for transmitting the data signal to the pixel array 110, so that the pixel array 110 can display an image on the pixel array according to the gate driving signal and the data signal. In some further embodiments, the pixel array 110 can display images on a display screen different from the pixel array according to the gate driving signal and the data signal.

The above-described settings of the sensing system 100 are for illustrative purposes only. A variety of different sensing systems 100 are within the contemplation and scope of this disclosure.

in reference to Figure 2. FIG. 2 is a schematic diagram of a light sensing circuit 200 shown in accordance with some embodiments of the present disclosure. As shown in FIG. 2 , the light sensing circuit 200 includes a light sensing transistor M1 , a light sensing transistor M2 , a light sensing transistor M3 , a capacitor C1 , a capacitor C2 , a switching element Tsw1 and a switching element Tsw2 .

The phototransistor M1 is covered by the color filter CF1. The color filter CF1 is used to pass the first color light. For example, the first color light is red light, and the light with a wavelength range of 620-750 nm (the wavelength range of red light) is easier to pass through the filter element than other color lights outside the range. . When the light containing the first color light is irradiated to the phototransistor M1, the first color light penetrates the color filter CF1 to the phototransistor M1, so that the phototransistor M1 can sense the first color light. The phototransistor M2 is covered by the color filter CF2. The phototransistor M3 is covered by the color filter CF3. The color filter CF2 and the color filter CF3 are respectively used for passing the second color light and the third color light, and their functions are similar to that of the color filter CF1, and are not repeated here.

In some embodiments, the first color light, the second color light and the third color light are different from each other. For example, the first color light is red, the second color light is blue, and the third color light is green. The above-mentioned first color light, second color light and third color light are for illustrative purposes only, and various arrangements of the first color light, second color light and third color light are all within the consideration and scope of the present disclosure.

As shown in FIG. 2 , the phototransistor M1, the phototransistor M2 and the phototransistor M3 respectively have a first end, a second end and a control end, the capacitor C1 and the capacitor C1 respectively have a first end and a second end, and the switching element Tsw1 and the switching element Tsw2 respectively have a first terminal, a second terminal and a control terminal. The control end of the phototransistor M1 , the control end of the phototransistor M2 , the second end of the phototransistor M2 and the control end of the phototransistor M3 are used for receiving the sensing signal Sn1 . The second end of the phototransistor M1 is coupled to the first end of the phototransistor M2 , the first end of the phototransistor M3 and the first end of the capacitor C2 . The first terminal of the phototransistor M1 is coupled to the second terminal of the switching element Tsw2. The second terminal of the phototransistor M3 and the second terminal of the capacitor C1 are used for receiving the voltage VSH. The first end of the switch element Tsw2 is coupled to the first end of the capacitor C1 and the second end of the switch element Tsw1. The first end of the capacitor C2 is used for receiving the sensing signal Sn2. The control terminal of the switching element Tsw2 is used for receiving the control signal Gsw2. The control terminal of the switching element Tsw1 is used for receiving the control signal Gsw1. The first end of the switching element Tsw1 is used for outputting the sampling signal Sout.

In some embodiments, the light sensing circuit 200 is configured to perform two sensings in the same frame, and one frame includes the first subframe SF1 and the second subframe SF2 (shown in FIG. 3 ). The light sensing circuit 200 is used to sense the light of the first color in the first subframe SF1 and the light of the second color in the second subframe SF2. In other words, the light sensing circuit 200 can sense light of two different colors using the same circuit. The operation of the light sensing circuit 200 is discussed later in conjunction with FIGS. 3-8.

Refer to Figure 3. FIG. 3 is a signal waveform diagram illustrating an operation mode of the light sensing circuit 200 of FIG. 2 in one frame according to some embodiments of the present disclosure. As shown in FIG. 3 , the signal waveform diagram shows the control signal Gsw1 , the control signal Gsw2 , the sensing signal Sn1 and the sensing signal Sn2 . The first subframe SF1 includes a first initialization operation Iini1, a first sensing operation Isen1 and a first sampling operation Isam1. The second subframe SF2 includes a second initialization operation Iini2, a second sensing operation Isen2 and a second sampling operation Isam2. In the operation mode, the first initialization operation Iini1 , the first sensing operation Isen1 , the first sampling operation Isam1 , the second initialization operation Iini2 , the second sensing operation Isen2 and the second sampling operation Isam2 are sequentially performed according to time t.

The first initialization operation Iini1 in the first subframe SF1 and the second initialization operation Iini2 in the second subframe SF2 are described with reference to FIG. 4 . The first sensing operation Isen1 in the first subframe SF1 is described with reference to FIGS. 5A to 5B . The first sampling operation Isam1 in the first subframe SF1 is described with reference to FIG. 6 . The second sensing operation Isen2 in the second subframe SF2 is described with reference to FIGS. 7A to 7B . The second sampling operation Isam2 in the second subframe SF2 is described with reference to FIG. 8 .

Refer to Figures 4 to 8. FIG. 4 is a schematic diagram of the light sensing circuit 200 shown in accordance with some embodiments of the present disclosure and the signal waveform diagram shown in FIG. 3 . FIGS. 5A and 5B are schematic diagrams of the light sensing circuit 200 according to some embodiments of the present disclosure and the signal waveforms shown in FIG. 3 . FIG. 6 is a schematic diagram of the light sensing circuit 200 shown in accordance with some embodiments of the present disclosure in combination with the signal waveform diagram shown in FIG. 3 . FIGS. 7A and 7B are schematic diagrams of the light sensing circuit 200 according to some embodiments of the present disclosure and the signal waveform diagram shown in FIG. 3 . FIG. 8 is a schematic diagram of the light sensing circuit 200 shown in accordance with some embodiments of the present disclosure and the signal waveform diagram shown in FIG. 3 .

In some embodiments, the first initialization operation Iini1 and the second initialization operation Iini2 are used to reset the potentials of the capacitors C1 and C2 so that the light sensing circuit 200 can be ready to start sensing light signals.

In the first initialization operation Iini1 , referring to FIGS. 3 to 4 , the sensing signal Sn1 has a potential capable of turning on the phototransistor M1 , the phototransistor M2 , and the phototransistor M3 , eg, about 15V. The sensing signal Sn2 has a low level, eg, about 0V. The control signal Gsw1 has a low potential capable of turning off the switching element Tsw1, eg, about -10V. The control signal Gsw2 has a high potential capable of turning on the switching element Tsw2, eg, about 25V. The photo-sensing transistor M1 , the photo-sensing transistor M2 , the photo-sensing transistor M3 and the switching element Tsw2 of the photo-sensing circuit 200 are turned on, and the switching element Tsw1 is turned off. Therefore, as shown in FIG. 4 , the capacitors C1 and C2 are charged by the voltage VSH and the sensing signal Sn1 through the path P1 . In the first initialization operation Iini1, the capacitors C1 and C2 are reset to a potential, which is close to the potential of the voltage VSH and the sensing signal Sn1, for example, about 15V. The second initialization operation Iini2 is similar to the first initialization operation Iini1, and details are not described herein again.

In some embodiments, the first sensing operation Isen1 is used for sensing the first color light, the second color light and the third color light, and for determining whether the light sensing circuit 200 senses the first color light and the second color light Mixed light. For example, if the first color light is blue light, the second color light is red light, and the mixed color light of red light and blue light is purple light, the light sensing circuit 200 is used for sensing whether there is purple light in the first sensing operation Isen1.

In the first sensing operation Isen1, referring to FIGS. 3, 5A, and 5B, the sensing signal Sn1 has a potential capable of turning off the phototransistor M1, the phototransistor M2, and the phototransistor M3, eg, about -10V. The sensing signal Sn2 has a low level, eg, about 0V. The control signal Gsw1 has a low potential capable of turning off the switching element Tsw1, eg, about -10V. The control signal Gsw2 has a high potential capable of turning on the switching element Tsw2, eg, about 25V.

In some embodiments, the light source L illuminates the light sensing circuit 200 , wherein the light source L includes the first color light and the second color light, and does not include the third color light. As shown in FIG. 5A , the phototransistor M1 and the phototransistor M2 conduct a leakage current because a leakage path is generated by sensing the first color light and the second color light. The switching element Tsw1 is turned off, the switching element Tsw2 is turned on, and the phototransistor M1 and the phototransistor M2 leak the charges stored in the capacitors C1 and C2 to the second end of the phototransistor M2 through the path P2. Therefore, the potential of the first terminal of the capacitor C1 and the potential of the second terminal of the capacitor C2 are reduced and are lower than a voltage threshold Vth1, for example, to about -10V.

In some embodiments, the light source L illuminates the light sensing circuit 200 , wherein the light source L includes the first color light, the second color light and the third color light. As shown in FIG. 5B , the phototransistor M1 , the phototransistor M2 and the phototransistor M3 generate leakage paths because they sense the first color light, the second color light and the third color light respectively. The phototransistor M2 and the phototransistor M3 leak electricity to the second end of the phototransistor M2 through the path P3. In some embodiments, since the leakage capability of the path P3 is stronger than that from the capacitors C1 and C2, the stored charges of the capacitors C1 and C2 are not easily leaked, and the potentials of the capacitors C1 and C2 do not change. In other words, when the light source L includes the first color light, the second color light and the third color light, for example, the light source L is strong white light (also called ambient light), because the phototransistor M3 generates a strong leakage path, the capacitor C1 and the capacitor C2 The stored charges do not leak, so that the light sensing circuit 200 can distinguish whether the light source L includes the first color light and the second color light, and does not include the third color light. In some embodiments, the phototransistor M3 is referred to as an ambient light compensation unit.

In other embodiments, the light source L illuminates the light sensing circuit 200 , wherein the light source L includes the second color light and the third color light, and does not include the first color light. The phototransistor M1 does not generate a leakage path. Therefore, the voltage of the capacitor C1 does not change.

In the first sensing operation Isen1, when the light source L only includes the first color light and the second color light, the potential of the first end of the capacitor C1 will decrease and be lower than the voltage threshold Vth1.

In some embodiments, the first sampling operation Isam1 is used to sample the potential on the first end of the capacitor C1 and output the sampling signal Sout.

In the first sampling operation Isam1 , referring to FIGS. 3 and 6 , the sensing signal Sn1 has a potential that can turn off the phototransistor M1 , the phototransistor M2 , and the phototransistor M3 , for example, about -10V. The sensing signal Sn2 has a low level, eg, 0V. The control signal Gsw1 has a high potential capable of turning on the switching element Tsw1, eg, about 25V. The photo-sensing transistor M1 , the photo-sensing transistor M2 and the photo-sensing transistor M3 of the photo-sensing circuit 200 are turned off, and the switching element Tsw1 is turned on. Regardless of whether the switching element Tsw2 is turned on or not, as shown in FIG. 6 , the potential of the first end of the capacitor C1 is transmitted to the first end of the switching element Tsw1 through the path P4 , and the sampling signal Sout is output.

As illustrated in FIGS. 5A and 5B , if the potential of the sampling signal Sout is lower than the voltage threshold Vth1 , it means that the light sensing circuit 200 senses the first color light and the second color light, and does not sense the third color light. If the potential of the sampling signal Sout is higher than the voltage threshold Vth1, it means that the sensing circuit 200 senses a combination of other light sources or no light source is sensed.

In some embodiments, the second sensing operation Isen2 is used to sense the first color light, the second color light and the third color light, and is used to determine whether the light sensing circuit 200 only senses the first color light.

In the second sensing operation Isen2, referring to FIGS. 3, 7A, and 7B, the sensing signal Sn1 has a potential that can turn off the phototransistor M1, the phototransistor M2, and the phototransistor M3, eg, about -10V. The sensing signal Sn2 has a higher potential, eg, about 15V, than in the second initialization operation. The control signal Gsw1 has a low potential capable of turning off the switching element Tsw1, eg, about -10V. The control signal Gsw2 has a high potential capable of turning on the switching element Tsw2, eg, about 25V.

In some embodiments, the light source L illuminates the light sensing circuit 200 , wherein the light source L only includes the first color light. As shown in FIG. 7A , the phototransistor M1 generates a leakage path due to sensing the first color light. The potential of the second end of the capacitor C2 is increased due to the increase of the sensing signal Sn2. Therefore, the potential of the second end of the capacitor C2 is higher than the potential of the first end of the capacitor C1. The charge stored on the second end of the capacitor C2 leaks to the capacitor C1 through the path P5. Therefore, the potential of the first terminal of the capacitor C1 is increased, and is higher than a voltage threshold Vth2, for example, to about 22V.

In some embodiments, the light source L illuminates the light sensing circuit 200 , wherein the light source L includes the first color light, the second color light and the third color light. As shown in FIG. 7B , the phototransistor M1 , the phototransistor M2 and the phototransistor M3 generate leakage paths because they sense the first color light, the second color light and the third color light respectively. The potential on the second end of the capacitor C2 raised by the increase of the sensing signal Sn2 leaks electricity to the second end of the phototransistor M2 and the second end of the phototransistor M3 through the path P6. Because the leakage capability of the path P6 is stronger than the capability of leakage to the capacitor C1, the electric charge stored in the capacitor C2 is not easily leaked to the capacitor C1, and the potential of the capacitor C1 does not change.

In the second sensing operation Isen2, when the light source L contains only the first color light, the potential of the first end of the capacitor C1 will be raised and higher than the voltage threshold Vth2.

In some embodiments, the second sampling operation Isam2 is used to sample the potential on the first end of the capacitor C1 and output the sampling signal Sout.

In the second sampling operation Isam2, referring to FIGS. 3 and 8, the sensing signal Sn1 has a potential that can turn off the phototransistor M1, the phototransistor M2, and the phototransistor M3, for example, about -10V. The control signal Gsw1 has a high potential capable of turning on the switching element Tsw1, eg, about 25V. The control signal Gsw2 has a low potential capable of turning off the switching element Tsw2, eg, about -10V. The photo-sensing transistor M1 , the photo-sensing transistor M2 , the photo-sensing transistor M3 and the switching element Tsw2 of the photo-sensing circuit 200 are turned off, and the switching element Tsw1 is turned on. As shown in FIG. 8 , the potential of the first end of the capacitor C1 is transmitted to the first end of the switching element Tsw1 through the path P7, and the output is the sampling signal Sout.

Based on the descriptions in Figs. 3 to 8, the voltage threshold Vth2 is greater than the voltage threshold Vth1. Therefore, the potential of the sampling signal Sout can be divided into three intervals by the voltage threshold Vth1 and the voltage threshold Vth2, that is, the interval less than the voltage threshold Vth1, the interval greater than or equal to the voltage threshold Vth1 The voltage threshold value Vth1 is equal to or smaller than the voltage threshold value Vth2, and the interval is greater than the voltage threshold value Vth2. In some embodiments, the interval less than the voltage threshold Vth1 is called the sampling low potential, the interval greater than or equal to the voltage threshold Vth1 and less than or equal to the voltage threshold Vth2 is called the sampling medium potential, and the interval greater than the voltage threshold Vth2 is called the sampling high potential. In the first sub-frame SF1, when the sampling signal Sout is at the sampling low level, it means that the light sensing circuit 200 senses the mixed color light of the first color light and the second color light, and when the sampling signal Sout is at the sampling medium level , it means that the light sensing circuit 200 does not sense the mixed color light of the first color light and the second color light. In the second subframe SF2, when the sampling signal Sout is in the sampling high potential range, it means that the light sensing circuit 200 senses the pure first color light, and when the sampling signal Sout is in the sampling mid potential range, it means the light The sensing circuit 200 does not sense the pure first color light.

The above operations and the combination of the first color light, the second color light and the third color light are for illustrative purposes only. Various combinations of manipulations and shades are within the contemplation and scope of this disclosure. For example, when the first color light is red light, the second color light is green light, and the third color light is blue light, the sensing circuit 200 is used to sense whether there is a mixed color light of red light and green light yellow in the first subframe SF1 light, and in the second subframe SF2 to sense whether there is pure red light.

Refer to Figure 9. FIG. 9 is a waveform diagram of a scan operation shown in accordance with some embodiments of the present disclosure. In some embodiments, the sensing signal Sn1 and the sensing signal Sn2 of the light sensing circuits 200 in the plurality of pixels in the pixel array 110 are the same, wherein the control signal Gsw1 in each light sensing circuit 200 is in a different Time enables the switching element Tsw1 in each light sensing circuit 200 to be turned on, so that the light sensing circuits 200 in a plurality of pixels in the pixel array 110 can sense simultaneously, and turn on the switching element Tsw1 time-divisionally to read the sampling signal Sout.

As shown in FIG. 9 , the control signal Gswn+1, the control signal Gswn+2, the control signal Gswn+3, the control signal Gswn+4 and the control signal Gswn+x respectively represent the control in the light sensing circuit 200 in different pixels Signal Gsw1. In FIG. 9 , the control signal Gsw1, the control signal Gswn+1, the control signal Gswn+2, the control signal Gswn+3, the control signal Gswn+4 and the control signal Gswn+x respectively have different time periods that enable the switching element Tsw1 to be turned on. potential. Therefore, the light sensing circuits 200 of the plurality of pixels in the pixel array 110 can realize the functions of sensing in the same period and reading the sampling signals in time division.

In some embodiments, the time length of the first subframe SF1 and the second subframe SF2 is about 8ms, the time length of the first initialization operation Iini1 and the second initialization operation Iini2 is about 1ms, the first sensing operation Isen1 and the first The time length of the second sensing operation Isen2 is about 4 ms, and the time length between the first sensing operation Isen1 and the second initialization operation Iini2 is about 3 ms. In other embodiments, in the second sensing operation Isen2, the control signal Gsw2 has a potential capable of turning off the switching element Tsw2 after about 0.5 ms of the sensing signal Sn2 increasing the potential.

In some embodiments, the control signal Gsw1, the control signal Gswn+1, the control signal Gswn+2, the control signal Gswn+3, the control signal Gswn+4 and the control signal Gswn+x are transmitted through different control lines and are transmitted through the same data line Each sampled signal Sout is transmitted to the processing circuit 130 . Therefore, the control signal Gsw1, the control signal Gswn+1, the control signal Gswn+2, the control signal Gswn+3, the control signal Gswn+4 and the control signal Gswn+x have potentials that can turn on the switching element Tsw1 at different time periods from each other, so that the The sampling signals Sout of each light sensing circuit 200 do not interfere with each other.

The lengths of time in Figure 9 above are for illustrative purposes only. Various lengths of time are within the contemplation and scope of this disclosure. For example, the time length of the first subframe SF1 is greater than 8ms.

Refer to Figure 10. FIG. 10 is a schematic diagram of a light sensing circuit 200 according to other embodiments of the present disclosure. Compared with FIG. 2 , as shown in FIG. 10 , the light sensing circuit 200 further includes an output circuit 210 , and the output circuit 210 includes a switching element Tsw3 and a switching element Tsw4 .

The switching element Tsw3 has a first terminal, a second terminal and a control terminal. The switching element Tsw4 has a first terminal, a second terminal and a control terminal. The control terminal of the switching element Tsw3 is used for receiving the sampling signal Sout. The first end of the switching element Tsw3 is used for receiving the supply voltage VDD. The second terminal of the switching element Tsw3 is coupled to the first terminal of the switching element Tsw4. The control end of the switching element Tsw4 is coupled to a control line, and receives the control signal Gn through the control line. The second end of the switching element Tsw4 is coupled to a data line, and outputs the output signal Ss through the data line. In some embodiments, the switching element Tsw3 and the switching element Tsw4 are used to amplify the sampling signal Sout to output the output signal Ss.

In some embodiments, the pixels in each row of the pixel array 110 are coupled to the same data line, and the pixels in each column are coupled to the same control lines. Therefore, the pixel array 110 includes a plurality of data lines and a plurality of control lines. By controlling the data line and the control line, the pixel array 110 can output the output signal Ss of a specific pixel in the array.

In some embodiments, the magnitude of the potential of the sampling signal Sout is related to the voltage of the second terminal of the switching element Tsw3. The supply voltage VDD is transmitted from the first end of the switching element Tsw3 to the second end of the switching element Tsw3, and the voltage drop therein is related to the magnitude of the potential of the sampling signal Sout.

Refer to Figure 11. FIG. 11 is a signal waveform diagram illustrating the operation of the light sensing circuit 200 in FIG. 10 according to other embodiments of the present disclosure. Compared with FIG. 3 , as shown in FIG. 11 , the signal waveform diagram also includes the waveform diagram of the control signal Gn.

In the first sampling operation Isam1 and the second sampling operation Isam2, the control signal Gn has a potential capable of turning on the switching element Tsw4, and at other times, the control signal Gn has a potential capable of turning off the switching element Tsw4. As shown in FIG. 11 , the time for the control signal Gn to have a potential capable of turning on the switching element Tsw4 in the first sampling operation Isam1 is shorter than the time for the first sampling operation Isam1, and the time for the control signal Gn to have the potential to enable the second sampling operation Isam2 The time for the potential of the switching element Tsw4 to be turned on is shorter than the time for the second sampling operation Isam2.

In the first sampling operation Isam1, the potential of the control signal Gsw1 is increased first, and the control signal Gn is increased after the potential of the control signal Gsw1 is increased. Before the end of the first sampling operation Isam1, the potential of the control signal Gn is lowered to turn off the switching element Tsw4.

In the second sampling operation Isam2, the potential of the control signal Gsw1 is increased first, and the control signal Gn is increased after the potential of the control signal Gsw1 is increased. Before the end of the second sampling operation Isam2, the potential of the control signal Gn is lowered to turn off the switching element Tsw4.

In some embodiments, in the first sampling operation Isam1, the switching element Tsw3 transmits the supply voltage VDD from the first terminal to the second terminal of the switching element Tsw3 according to the sampling signal Sout, wherein the voltage change is related to the sampling signal Sout. After the supply voltage VDD is transmitted to the second terminal of the switching element Tsw3, the switching element Tsw4 is turned on, as shown in the waveform diagram of the control signal Gn in FIG. 11, and the voltage at the second terminal of the switching element Tsw3 related to the sampling signal Sout The output is the output signal Ss.

Refer to Figure 12. 12 is a schematic diagram of pixel layouts 1200A, 1200B, 1200C shown in accordance with some embodiments of the present disclosure.

In some embodiments, the phototransistor M1 , the phototransistor M2 , the phototransistor M3 , the switching element Tsw1 and the switching element Tsw2 in the photo sensing circuit 200 are implemented by thin film transistors (TFTs).

As shown in FIG. 12, the pixel layout 1200A is a layout diagram of one pixel PI. The pixel layout 1200A includes three sub-pixels, the layout of the first sub-pixel SPI includes the phototransistor M1 and the switching element Tsw2, the layout of the second sub-pixel SPI includes the phototransistor M2, and the layout of the third sub-pixel SPI includes the phototransistor M2. Inductive transistor M3 and switching element Tsw1.

As shown in FIG. 12, the pixel layout 1200B is a layout diagram of two pixels PI. The pixel layout 1200B includes six sub-pixels, the layout of the first sub-pixel SPI includes a photo-sensing transistor M1, the layout of the second sub-pixel SPI includes a photo-sensing transistor M2 and a switching element Tsw1, and the layout of the third sub-pixel SPI includes a photo-sensing transistor M2. The transistor M3 and the switching element Tsw2.

In some embodiments, the phototransistor in the pixel is replaced by two smaller phototransistors in parallel because the opening area is too large. For example, the phototransistor M1 is replaced by the phototransistor M1a and the phototransistor M1b in parallel. , the phototransistor M2 is replaced by the phototransistor M2a and the phototransistor M2b in parallel, and the phototransistor M3 is replaced by the phototransistor M3a and the phototransistor M3b in parallel. The opening area of each of the phototransistor M1a and the phototransistor M1b is smaller than that of the phototransistor M1, and the opening area of each of the phototransistor M2a and the phototransistor M2b is smaller than that of the phototransistor M2. And the opening area of each of the phototransistor M3a and the phototransistor M3b is smaller than that of the phototransistor M3.

As shown in FIG. 12, the pixel layout 1200C is a layout diagram of two pixels PI. The pixel layout 1200C includes six sub-pixels, the layout of the first column of sub-pixels SPI includes a photo-transistor M1a and a photo-transistor M1b, the layout of the second column of sub-pixels SPI includes a photo-transistor M2a, a photo-transistor M2b and a switching element Tsw1, and The layout of the three-column sub-pixels SPI includes a phototransistor M3a, a phototransistor M3b, and a switching element Tsw2.

In some embodiments, in the pixel layout 1200A, the pixel layout 1200B, and the pixel layout 1200C, the area with the phototransistor and the switching element is a non-light-emitting area, and the rest is a light-emitting area, which is used for display.

The pixel layout 1200A, the pixel layout 1200B, and the pixel layout 1200C described above are for illustrative purposes only. Various different pixel layouts are within the contemplation and scope of this disclosure.

Refer to Figure 13. FIG. 13 is a schematic diagram of a light sensing circuit 300 according to other embodiments of the present disclosure. As shown in FIG. 13 , the light sensing circuit 300 includes a light sensing transistor M4, a light sensing transistor M5, a light sensing transistor M6, a light sensing transistor M7, a light sensing transistor M8, a light sensing transistor M9, a capacitor C3, a capacitor C4, and a switching element Tsw5, switching element Tsw6, and switching element Tsw7.

The phototransistor M4, the phototransistor M5, the phototransistor M6, the phototransistor M7, the phototransistor M8, the phototransistor M9, the switching element Tsw5, the switching element Tsw6 and the switching element Tsw7 all have a first end and a second end and the control side. Both the capacitor C3 and the capacitor C4 have a first terminal and a second terminal.

As shown in FIG. 13 , the first terminal and the control terminal of the phototransistor M4 are coupled to the second terminal of the switching element Tsw7 . The second end of the phototransistor M4 is coupled to the first end of the phototransistor M5 , the control end of the phototransistor M5 and the first end of the phototransistor M6 . The second end of the phototransistor M5 and the second end of the phototransistor M8 are used for receiving the sensing signal Sn3. The second terminal and the control terminal of the phototransistor M6, the second terminal and the control terminal of the phototransistor M9, and the second terminal of the capacitor C4 are used for receiving the voltage VSL. The control terminal of the switching element Tsw7 is used for receiving the control signal Gsw7. The first end of the switch element Tsw7 is coupled to the first end of the capacitor C3 and the second end of the switch element Tsw6. The second end of the capacitor C3 is used for receiving the sensing signal Sn4. The control terminal of the switching element Tsw6 is used for receiving the control signal Gsw6. The first end of the switch element Tsw6 is coupled to the first end of the phototransistor M7 , the first end of the capacitor C4 and the second end of the switch element Tsw5 . The control terminal and the second terminal of the phototransistor M7 are coupled to the first terminal of the phototransistor M8, the control terminal of the phototransistor M8 and the first terminal of the phototransistor M9. The control terminal of the switching element Tsw5 is used for receiving the control signal Gsw5. The second end of the switching element Tsw5 is used for outputting the sampling signal Sout.

In some embodiments, the phototransistor M7 and the phototransistor M8 are used for sensing the first color light, the phototransistor M4 and the phototransistor M5 are used for sensing the second color light, and the phototransistor M6 and the phototransistor are used for sensing the second color light. M9 is used for sensing the third color light. The phototransistor M4, the phototransistor M5, the phototransistor M6, the phototransistor M7, the phototransistor M8, and the phototransistor M9 are respectively composed of a color filter CF4, a color filter CF5, a color filter CF6, and a color filter CF7. , The color filter CF8 and the color filter CF9 are covered. The color filter CF7 and the color filter CF8 are used to pass the first color light. The color filter CF4 and the color filter CF5 are used for passing the second color light. The color filter CF6 and the color filter CF9 are used to pass the third color light.

The light sensing circuit 300 is used for performing two sensings in the same frame, and one frame includes the first subframe SF1 and the second subframe SF2 (shown in FIG. 14 ). The light sensing circuit 300 is used to sense the light of the first color in the first subframe SF1 and the light of the second color in the second subframe SF2. In other words, the light sensing circuit 300 can sense light of two different colors by using the same circuit. The operation of the light sensing circuit 300 is discussed later in conjunction with FIG. 14 .

Refer to Figure 14. FIG. 14 is a signal waveform diagram illustrating the operation mode of the light sensing circuit 300 in FIG. 13 in one frame according to other embodiments of the present disclosure. As shown in FIG. 14 , the signal waveform diagram shows the control signal Gsw5 , the control signal Gsw6 , the control signal Gsw7 , the sensing signal Sn3 and the sensing signal Sn4 . The first subframe SF1 includes a first initialization operation Iini1, a first sensing operation Isen1 and a first sampling operation Isam1. The second subframe SF2 includes a second initialization operation Iini2, a second sensing operation Isen2 and a second sampling operation Isam2. In the operation mode, the first initialization operation Iini1 , the first sensing operation Isen1 , the first sampling operation Isam1 , the second initialization operation Iini2 , the second sensing operation Isen2 and the second sampling operation Isam2 are sequentially performed according to time t.

In the first subframe SF1, the control signal Gsw6 has a potential to turn off the switching element Tsw6. In FIG. 13, in the first subframe SF1, the circuit on the left side of the switching element Tsw6 and the circuit on the right side of the switching element Tsw6 operate independently of each other,

In some embodiments, in the first sensing operation Isen1, the sensing signal Sn3 has a high potential. If the phototransistor M7 and the phototransistor M8 sense the first color light, the first end of the capacitor C4 will is charged and has a high potential, and if the phototransistor M4 and the phototransistor M5 sense the second color light, the first end of the capacitor C3 will be charged and have a high potential and the first end of the capacitor C4 will be charged and has a high potential. In other embodiments, if the light sensing circuit 300 is irradiated by strong white light, the light sensing transistor M6 and the light sensing transistor M9 generate a leakage path, so that the capacitor C3 and the capacitor C4 cannot be charged.

In some embodiments, in the first sampling operation Isam1, the switching element Tsw5 is turned on, and outputs the potential on the first end of the capacitor C4 as the sampling signal Sout. If the sampling signal Sout has a high level charged by the sensing signal Sn3, it means that the light sensing circuit 300 senses the first color light.

In some embodiments, in the second sensing operation Isen2, the sensing signal Sn4 increases, and if the light sensing circuit 300 senses the second color light in the first sensing operation Isen1, the second color light stored in the capacitor C3 The potential of one end increases as the sensing signal Sn4 increases. And, the switching element Tsw6 is turned on in the second sensing operation Isen2, and the electric charge generated by the electric potential raised by the capacitor C3 flows to the first end of the capacitor C4. Therefore, in the second sampling operation Isam2, if the sampling signal Sout has a potential that is charged by the sensing signal Sn3 and then charged by the sensing signal Sn4, it means that the light sensing circuit 300 senses the first color light and the second color light Color mixing light.

In some approaches, if a light-sensing circuit is to sense two different colors of light, two circuits with different structures are required for implementation. Therefore, the area of a single pixel is greatly increased and the resolution is decreased.

Compared with the above method, in the embodiment of the present disclosure, the light sensing circuit 200 and the light sensing circuit 300 are used to sense two different colors of light with one circuit structure, without greatly increasing the circuit area and maintaining the resolution , to increase the performance of the circuit.

Although the embodiments of the present disclosure have been disclosed above, they are not intended to limit the embodiments of the present disclosure. Any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, The protection scope of the embodiments of the present disclosure should be defined by the claims.

Claims (10)

1. A light sensing circuit, comprising: a first phototransistor, comprising a first end, a second end and a control end, the first phototransistor is used for sensing a first color light; a second phototransistor, comprising a first end, a second end and a control end, the second phototransistor is used for sensing a second color light; a third phototransistor, comprising a first end, a second end and a control end, the third phototransistor is used for sensing a third color light; a first capacitor, including a first end and a second end; a second capacitor, including a first end and a second end; a first switch element coupled to the first end of the first capacitor for outputting a sampling signal; and a second switch element coupled between the first end of the first phototransistor and the first end of the first capacitor, The second end of the first phototransistor is coupled to the first end of the second phototransistor, the first end of the third phototransistor and the second end of the second capacitor. The control end of a phototransistor, the control end of the second phototransistor, the second end of the second phototransistor, and the control end of the third phototransistor are used to receive a first sensing signal , the second end of the third phototransistor and the second end of the first capacitor are used to receive a first voltage, and the first end of the second capacitor is used to receive a second sensing signal. 2 . The light sensing circuit of claim 1 , wherein the first light sensing transistor is covered by a first color filter, the first color filter is used for passing the first color light, the second light sensing The transistor is covered by a second color filter for passing the second color light, the third phototransistor is covered by a third color filter, and the third color filter is used for passing the second color light Tertiary light. 3. The light sensing circuit of claim 1, wherein the light sensing circuit operates in an operation mode, the operation mode comprising a first sensing operation and a second sensing operation. 4. The light sensing circuit of claim 3, wherein the first sensing operation is used to turn off the first phototransistor, turn off the second phototransistor, turn off the third phototransistor, and turn off the first phototransistor a switch element and turn on the second switch element for sensing the first color light, the second color light and the third color light, and The second sensing operation is used for turning off the first phototransistor, turning off the second phototransistor, turning off the third phototransistor, turning off the first switch element, and turning on the second switch element, and used for sensing the first color light, the second color light and the third color light. 5. The light sensing circuit of claim 4, wherein in the first sensing operation, when the sampling signal is less than a first voltage threshold, the first phototransistor senses the first color light , the second phototransistor senses the second color light, and the third sensing element does not sense the third color light. 6. The light sensing circuit of claim 5, wherein in the second sensing operation, when the sampling signal is greater than a second voltage threshold, the first phototransistor senses the first color light , the second phototransistor does not sense the second color light, and the third sensing element does not sense the third color light. 7. The light sensing circuit of claim 6, wherein the second voltage threshold is greater than the first voltage threshold. 8. The light sensing circuit of claim 4, wherein in the first sensing operation, the second sensing signal has a second voltage, and in the second sensing operation, the second sensing The test signal has a third voltage, wherein the third voltage is greater than the second voltage. 9. The light sensing circuit of claim 3, wherein the operation mode further comprises a first sampling operation and a second sampling operation, Wherein the first sampling operation is used to turn on the first switch element, and output a voltage of the first end of the first capacitor as the sampling signal through the first switch element, and the second sampling operation is used to turn on the a first switch element, turning off the second switch element, and outputting the voltage of the first end of the first capacitor through the first switch element as the sampling signal, and The first sampling operation is performed after the first sensing operation and before the second sensing operation, and the second sampling operation is performed after the second sensing operation. 10. The light sensing circuit of claim 1, wherein When the first phototransistor is turned off and the first color light is sensed, the first phototransistor is used for conducting a first current, When the second phototransistor is turned off and the second color light is sensed, the second phototransistor is used for conducting a second current, and When the third phototransistor is turned off and the third color light is sensed, the third phototransistor is used for conducting a third current.

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