A photoelectric detection circuit and a driving method thereof, and a photoelectric sensor

Abstract

The present disclosure provides a photoelectric detection circuit and a driving method thereof, and a photoelectric sensor, wherein the circuit includes: a photosensitive element, a source follower transistor, and a compensation circuit; wherein the compensation circuit is connected to the first electrode of the photosensitive element, the second electrode of the source follower transistor, the gate of the source follower transistor, the first control terminal, and the second control terminal, and the first electrode of the source follower transistor is connected to the working voltage; the compensation circuit is configured to: under the control of the first control terminal and the second control terminal, obtain the threshold voltage of the source follower transistor, and form a compensation voltage input to the gate of the source follower transistor according to the working voltage and the threshold voltage. The present disclosure sets a compensation circuit in the photoelectric detection circuit, and compensates the threshold voltage of the source follower transistor through the compensation circuit to eliminate the influence of the threshold voltage of the source follower transistor on the output current, thereby improving the detection uniformity and accuracy of the photoelectric electrical measurement circuit.

Description

Technical Field

[0001] The present disclosure relates to the field of photoelectric image sensor design and manufacturing, and in particular to a photoelectric detection circuit and a driving method thereof, and a photoelectric sensor. Background Art

[0002] Active Pixel Sensor (APS) is mainly used to convert optical signals into electrical signals. Figure 1 As shown, it mainly includes a photodiode (Pinned-Photodiode, PPD) transmission tube M TX , reset tube M RST , source follower M SF And the row gate tube M SEL The transmission tube can effectively reduce the thermal noise and dark current of the pixel, and the source follower plays an amplifying role, which can amplify the current generated by the photodiode and output it. Figure 2 for Figure 1 The working timing diagram of the pixel circuit shown in FIG. 1 is mainly divided into a reset phase, an integration phase and a transfer phase; Figure 1 Taking the transistors shown in the figure as N-type transistors as an example, in the reset stage, the reset signal RST=1, TX=1, the reset tube and the transmission tube are turned on, the FD point completes the reset, and the PPD is clamped to prepare for the photogenerated charge of the mobile phone; in the integration stage, RST=0, TX=0, the reset tube and the transmission tube are turned off, the photogenerated charge is collected by the PPD, SEL=1, that is, the row selection tube is turned on, and the reset signal of the FD point is output to the column line through the source follower, that is, the pixel output voltage in the reset stage; in the transfer stage, RST=0, TX=1, SEL=1, the transmission tube is turned on, the photogenerated charge accumulated by the PPD is transferred to the FD point, and the charge signal is converted into the output current and voltage. The voltage at the FD point (the voltage in the integration stage) is output to the column line again through the source follower, and can then be amplified and calculated by the signal amplification and calculation module outside the pixel structure. Therefore, the light intensity sensed by the photodiode can be obtained by measuring the current output by the source follower.

[0003] In actual use, the output current of the source follower changes with the change of the voltage at the FD point. However, due to the manufacturing process and long-term use, the body effect and in-plane uniformity between multiple transistor devices or TFTs are different, resulting in differences in the voltage or current output by different pixel structures. At the same time, the threshold voltage of the source follower will also drift. These phenomena will seriously affect the accuracy of the detection results. Summary of the invention

[0004] The purpose of the embodiments of the present disclosure is to provide a photoelectric detection circuit and a driving method thereof, and a photoelectric sensor, so as to solve the problem in the prior art that the different threshold voltages of multiple source followers lead to inaccurate detection results.

[0005] The embodiments of the present disclosure adopt the following technical solutions: a photodetection circuit, comprising: a photosensitive element, a source follower transistor and a compensation circuit; wherein the compensation circuit is connected to the first electrode of the photosensitive element, the first stage of the source follower transistor, the gate of the source follower transistor, the first control terminal and the second control terminal, and the first electrode of the source follower transistor is also connected to the operating voltage; the compensation circuit is configured to: under the control of the first control terminal and the second control terminal, obtain the threshold voltage of the source follower transistor, and form a compensation voltage according to the operating voltage and the threshold voltage to input to the gate of the source follower transistor.

[0006] In some embodiments, the compensation circuit includes at least: a first transistor, a second transistor, a fourth transistor and a first capacitor; wherein the first electrode of the first transistor is connected to the first electrode of the photosensitive element, the second electrode of the first transistor is connected to the second electrode of the fourth transistor and the first electrode of the first capacitor, the gate of the first transistor is connected to the first control terminal, the first electrode of the fourth transistor is connected to the operating voltage, the second electrode of the fourth transistor is connected to the second control terminal, the second electrode of the first capacitor is connected to the gate of the source follower transistor and the second electrode of the second transistor, the first electrode of the second transistor is connected to the second electrode of the source follower transistor, and the gate of the second transistor is connected to the first control terminal.

[0007] In some embodiments, when a valid level is input to the first control terminal and an invalid level is input to the second control terminal, the compensation circuit inputs the compensation voltage to the gate of the source follower transistor; when an invalid level is input to the first control terminal and a valid level is input to the second control terminal, the voltage applied to the first electrode of the first capacitor is adjusted from the photosensitivity voltage output by the photosensitive element to the working voltage, and the voltage applied to the gate of the source follower transistor is adjusted according to the voltage adjustment amplitude on the first electrode of the first capacitor, so that the induced current output by the second electrode of the source follower transistor is adjusted based on the magnitude of the photosensitivity voltage output by the photosensitive element.

[0008] In some embodiments, it also includes: a row selection tube, the first electrode of the row selection tube is connected to the second electrode of the source follower transistor, the gate of the row selection tube is connected to the second control terminal, and the second electrode of the row selection tube is used to output the detection current output by the source follower transistor.

[0009] In some embodiments, it also includes: a reset circuit; the reset circuit is connected to the photosensitive element, the compensation circuit, a first reset voltage terminal, a second reset voltage terminal and a third control terminal; the reset circuit is configured to reset the photosensitive element and the compensation circuit according to the control of the third control terminal, the first reset voltage terminal and the second reset voltage terminal.

[0010] In some embodiments, the reset circuit includes at least: a sixth transistor, a seventh transistor and an eighth transistor; wherein, the first electrode of the sixth transistor is connected to the first reset voltage terminal, the second electrode of the sixth transistor is connected to the first electrode of the first capacitor, the gate of the sixth transistor is connected to the third control terminal, the first electrode of the seventh transistor is connected to the first electrode of the photosensitive element, the second electrode of the seventh transistor is connected to the first reset voltage terminal, the gate of the seventh transistor is connected to the third control terminal, the first electrode of the eighth transistor is connected to the second reset voltage terminal, the second electrode of the eighth transistor is connected to the second electrode of the first capacitor, and the gate of the eighth transistor is connected to the third control terminal.

[0011] An embodiment of the present disclosure also provides a driving method for a photoelectric detection circuit as described above, comprising: a first stage: an invalid level is input to both the first control terminal and the second control terminal, and the photosensitive element collects photocharges; a second stage: a valid level is input to the first control terminal, an invalid level is input to the second control terminal, the photosensitive element outputs a photosensitive voltage, and the compensation circuit obtains the threshold voltage of the source follower transistor under the drive of the valid level, and forms a compensation voltage based on the operating voltage and the threshold voltage and inputs it to the gate of the source follower transistor; a third stage: an invalid level is input to the first control terminal, a valid level is input to the second control terminal, the voltage applied to the gate of the source follower transistor changes based on the size of the photosensitive voltage, and controls the second pole of the source follower transistor to output different detection currents.

[0012] In some embodiments, when the photoelectric detection circuit includes a reset circuit, before the first stage is executed, it also includes: a reset stage: the first control terminal and the second control terminal both input invalid levels, and the third control terminal inputs a valid level, and the reset circuit resets the photosensitive element and the compensation circuit based on the control of the first reset voltage terminal and the second reset voltage terminal.

[0013] An embodiment of the present disclosure further provides a photoelectric sensor, which at least includes the above-mentioned photoelectric detection circuit.

[0014] In some embodiments, the photosensor includes at least a plurality of the photosensor circuits arranged in an array.

[0015] In some embodiments, it also includes: a peripheral processing circuit, which is connected to the output end of the photoelectric detection circuit and is used to amplify and perform calculations on the induced current output by the photoelectric detection circuit.

[0016] The beneficial effect of the embodiments of the present disclosure is that a compensation circuit is provided in the photoelectric detection circuit, and the threshold voltage of the source follower transistor is compensated by the compensation circuit to eliminate the influence of the threshold voltage of the source follower transistor on the output current, thereby achieving improvement in the detection uniformity and accuracy of the photoelectric detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 is a structural schematic diagram of a pixel circuit in the related art;

[0019] Figure 2 It is a working timing diagram of a pixel circuit in the related art;

[0020] Figure 3 A schematic diagram of a photoelectric detection circuit in the first embodiment of the present disclosure;

[0021] Figure 4 A schematic diagram of a circuit structure of a photoelectric detection circuit in the first embodiment of the present disclosure;

[0022] Figure 5 In the first embodiment of the present disclosure Figure 4 The working timing diagram of the circuit structure shown;

[0023] Figure 6 is another schematic diagram of the photoelectric detection circuit in the first embodiment of the present disclosure;

[0024] Figure 7 is another circuit structure schematic diagram of the photoelectric detection circuit in the first embodiment of the present disclosure;

[0025] Figure 8 In the first embodiment of the present disclosure Figure 7 The working timing diagram of the circuit structure shown;

[0026] Fig. 9 FIG. 4 is a schematic diagram of an array of photosensors in a fourth embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] Various aspects and features of the present disclosure are described herein with reference to the drawings.

[0028] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but only as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0029] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0030] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the attached drawings.

[0031] It should also be understood that, although the present disclosure has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the features of the claims and are therefore within the scope of protection defined thereby.

[0032] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0033] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments claimed are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0034] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0035] In order to solve the technical problems existing in the photoelectric detection pixel circuit in the prior art, the first embodiment of the present disclosure provides a photoelectric detection circuit, which is mainly used for image recognition, for example, as a CMOS, CCD image sensor array, or as a detection sensor for fingerprint, palm print, facial recognition detection, etc. in smart devices. The photoelectric detection circuit provided in this embodiment is provided with a compensation circuit, and the compensation circuit is used to compensate the threshold voltage of the source follower transistor in the photoelectric detection circuit, thereby eliminating the influence of the threshold voltage of the source follower transistor on the output current. Figure 3 1 is a schematic diagram of a photoelectric detection circuit in this embodiment, which mainly includes a photosensitive element P, a source follower transistor M3 and a compensation circuit 10, wherein the compensation circuit 10 is connected to the first electrode of the photosensitive element P, the first stage of the source follower transistor M3, the gate of the source follower transistor M3, the first control terminal Scan1 and the second control terminal Scan2, and the first electrode of the source follower transistor M3 is also connected to the working voltage VDD. When actually performing photoelectric detection, the compensation circuit 10 will obtain the threshold voltage Vth of the source follower transistor M3 under the control of the first control terminal Scan1 and the second control terminal Scan2, and form a compensation voltage according to the threshold voltage Vth and the working voltage VDD and input it into the gate of the source follower transistor M3. The source follower transistor M3 can output a detection current corresponding to the voltage applied to its gate, and under the action of the compensation voltage, the output detection current will not be affected by the threshold voltage Vth, so as to achieve the purpose of accurately detecting the light intensity sensed by the photosensitive element P.

[0036] Figure 4 FIG. 1 shows a schematic diagram of a circuit structure of a photoelectric detection circuit. Figure 4 As shown, the compensation circuit 100 at least includes: a first transistor M1, a second transistor M2, a fourth transistor M4 and a first capacitor C, wherein two electrodes of the first capacitor C correspond to Figure 4 N1 and N2 in. Specifically, the first electrode of the first transistor M1 is connected to the first electrode of the photosensitive element P, the second electrode of the first transistor M1 is connected to the second electrode of the fourth transistor M4 and the first electrode N1 of the first capacitor C, the gate of the first transistor M1 is connected to the first control terminal Scan1, the first electrode of the fourth transistor M4 is connected to the operating voltage VDD, the second electrode of the fourth transistor M4 is connected to the second control terminal Scan2, the second electrode N2 of the first capacitor C is connected to the gate of the source follower transistor M3 and the second electrode of the second transistor M2, the first electrode of the second transistor M2 is connected to the second electrode of the source follower transistor M3, and the gate of the second transistor M2 is connected to the first control terminal Scan1.

[0037] Further, based on Figure 4The circuit structure shown in the figure can also include a row selection tube M5, a first electrode of which is connected to the second electrode of the source follower transistor M3, a gate of the row selection tube M5 is connected to the second control terminal Scan2, and the second electrode of the row selection tube M5 is used to output the detection current output by the source follower transistor M3. It can actually be connected to peripheral circuits such as an amplification unit and / or a processing unit according to needs to perform subsequent processing steps of the detection current.

[0038] exist Figure 4 When the photoelectric detection circuit shown in the figure is actually working, the components actually connected in the circuit are controlled according to the level values ​​inputted by the first control terminal Scan1 and the second control terminal Scan2, so as to complete the functions of collecting the photogenerated charge of the photosensitive element P, compensating the threshold voltage of the compensation circuit 10 or outputting the detection current of the source follower transistor M3, etc. The corresponding working timing diagram is shown in FIG. Figure 5 Specifically, Figure 5 In the stage t1 shown, both the first control terminal Scan1 and the second control terminal Scan2 input invalid levels, at which time M1 to M5 are all in the off state, and the photosensitive element P receives light to collect photogenerated charges; wherein, the magnitude of the photosensitive voltage Vpin output by the photosensitive element P and the light intensity received by the photosensitive element P follow a certain functional relationship, and the above functional relationship is usually a linear relationship, and its specific linear relationship or corresponding expression may change according to the parameters or properties of the photosensitive element P, which will not be described in detail in this embodiment.

[0039] Later, in Figure 5 In the stage t2 shown, the first control terminal Scan1 inputs a valid level, and the second control terminal Scan2 inputs an invalid level. At this time, M1 to M3 are turned on, the first electrode N1 writes the photosensitivity voltage Vpin output by the photosensitive element P, and the second electrode N2 writes the operating voltage VDD and the threshold voltage Vth of M3. Since the second electrode N2 is connected to the gate of the source follower transistor M3, the voltage value written on the second electrode N2 is the gate voltage of M3, that is, the voltage written on the gate of M3 is the compensation voltage formed by VDD and Vth, which ensures that M3 is always in the on state in the current stage.

[0040] Further, in Figure 5In the stage t3 shown, the first control terminal Scan1 is controlled to input an invalid level, and the second control terminal Scan2 is controlled to input a valid level. At this time, the voltage of the N1 node becomes VDD, and the adjustment range of its voltage is (VDD-Vpin). The N2 node is in a suspended state. Coupled by the voltage of the N1 node, the voltage change of the N2 node should be the same as the voltage change of the N1 node, that is, the voltage of the N2 node is increased by (VDD-Vpin) on the basis of the original compensation voltage. At this time, the voltage of the N2 node is (VDD+Vth+VDD-Vpin), that is to say, the voltage written on the gate of M3 at this time is (VDD+Vth+VDD-Vpin).

[0041] The detection current output by the source follower transistor M3 is determined based on its own transistor parameters and the voltage applied to its first electrode (source) and gate. The specific formula is as follows:

[0042]

[0043] Wherein, Vgs is the voltage difference between the gate voltage Vg and the source voltage Vs of M3, Vth is the threshold voltage of M3, W is the width of the channel in M3, L is the channel length of M3, μ is the carrier migration rate, and Cox is the unit area capacitance of the dielectric layer of M3. When M3 remains unchanged, the values ​​of the above parameters except Vgs are all constants, that is, the magnitude of the current value finally output by formula (1) is related to Vgs.

[0044] according to Figure 5 In the circuit structure shown, the first electrode of M3 is connected to the working voltage VDD, that is, Vs=VDD, and the gate of M3 is the same as the voltage of the N2 node, that is, Vg=VDD+Vth+VDD-Vpin. Substituting it into formula (1), the following formula is obtained:

[0045]

[0046] Right now,

[0047] Based on the above formula (3), it can be determined that the current value finally output by M3 has nothing to do with its own Vth value, but is only related to the value of the photosensitivity voltage Vpin output by the photosensitive element P. Therefore, the photoelectric detection circuit provided in this embodiment can realize Vth compensation for the source follower transistor M3, thereby improving the uniformity and accuracy of the circuit output result.

[0048] In some embodiments, the photoelectric detection circuit may also be provided with a reset circuit for resetting other components in the circuit to further improve the uniformity of circuit detection and avoid the situation where the accuracy is reduced due to the different initial states of each component when the photoelectric detection circuit is used for photoelectric detection. Specifically, Figure 6 As shown, the reset circuit 20 is mainly connected to the photosensitive element P and the compensation circuit 10 in the photoelectric detection circuit, and is also connected to the first reset voltage terminal Vint1, the second reset voltage terminal Vint2 and the third control terminal Scan3, so as to reset the photosensitive element P and each element in the compensation circuit 10 according to the reset voltage input by the first reset voltage terminal Vint1 and the second reset voltage terminal Vint2 under the control of the third control terminal Scan3.

[0049] Figure 7 A schematic diagram of the circuit structure of a photoelectric detection circuit is shown. Figure 4 On the basis of , a sixth transistor M6, a seventh transistor M7, and an eighth transistor M8 are added, a first electrode of the sixth transistor M6 is connected to the first reset voltage terminal Vint1, a second electrode of the sixth transistor M6 is connected to the first electrode N1 of the first capacitor C, a gate of the sixth transistor M6 is connected to the third control terminal Scan3, a first electrode of the seventh transistor M7 is connected to the first electrode of the photosensitive element P, a second electrode of the seventh transistor M7 is connected to the first reset voltage terminal Vint1, a gate of the seventh transistor M7 is connected to the third control terminal Scan3, a first electrode of the eighth transistor M8 is connected to the second reset voltage terminal Vint2, a second electrode of the eighth transistor M8 is connected to the second electrode N2 of the first capacitor C, and a gate of the eighth transistor M8 is connected to the third control terminal Scan3.

[0050] based on Figure 7 In the circuit structure shown, before the photosensitive element P collects the photogenerated charges, the third control terminal Scan3 is controlled to input a valid level, the first control terminal Scan1 and the second control terminal Scan2 are both input an invalid level, M6 to M8 are turned on, M1 to M5 are all in the off state, the N1 node and the photosensitive element P are reset based on the signal input by the first reset voltage terminal Vint1, and the N2 node is reset based on the signal input by the second reset voltage terminal Vint2. In actual implementation, the signals input by the first reset voltage terminal Vint1 and the second reset voltage terminal Vint2 can be the same signal or different signals, and both are DC signals. Figure 8 for Figure 7 The working timing diagram of the corresponding circuit is as follows: Figure 8 As shown, in Figure 5 The timing stages shown also include a reset stage t0 to achieve circuit reset.

[0051] It should be noted that all transistors in this embodiment can be thin film transistors (TFT), metal oxide semiconductor field effect transistors (MOSTET), or other triodes with the same function. The transistors can be N-type or P-type. The level values ​​input to each control terminal also vary according to the type of transistor, and are not specifically limited here. At the same time, the first electrode of the photosensitive element P is connected to the compensation circuit, and the second electrode thereof is connected to the DC bias voltage Vbias to drive the photosensitive element P. It can actually be used as follows Figures 3 to 7 The photosensitive diode shown in any of the figures may also be other organic or inorganic photosensitive devices, and this embodiment does not limit this. In addition, the implementation of the reset circuit 20 provided in this embodiment is only one implementation method that can be implemented. In actual implementation, an independent reset module or other circuit structure that can achieve the same reset effect may also be selected, and this embodiment does not specifically limit this.

[0052] The second embodiment of the present disclosure provides a driving method for a photoelectric detection circuit, which mainly includes: a first stage, a second stage and a third stage, referring to Figure 5 , when driving the photoelectric detection circuit, the following steps are mainly implemented in each stage:

[0053] Phase I (corresponding to Figure 5 Middle t1 stage):

[0054] Invalid levels are input to the first control terminal and the second control terminal, and the photosensitive element collects photoelectric charges; specifically, at this time, M1 to M5 are all in the off state, and the photosensitive element P receives light irradiation to collect photogenerated charges.

[0055] The second stage (corresponding to Figure 5 Middle t2 stage):

[0056] The first control terminal inputs a valid level, the second control terminal inputs an invalid level, the photosensitive element outputs a photosensitive voltage, and the compensation circuit, driven by the valid level, obtains the threshold voltage of the source follower transistor, and forms a compensation voltage based on the working voltage and the threshold voltage, which is input to the gate of the source follower transistor; specifically, at this time, M1 to M3 are turned on, the first electrode N1 writes the photosensitive voltage Vpin output by the photosensitive element P, and the second electrode N2 writes the working voltage VDD and the threshold voltage Vth of M3. Since the second electrode N2 is connected to the gate of the source follower transistor M3, the voltage value written on the second electrode N2 is the gate voltage of M3, that is, the voltage written on the gate of M3 is the compensation voltage formed by VDD and Vth, which ensures that M3 is always in the on state in the current stage.

[0057] The third stage (corresponding to Figure 5 Middle t3 stage):

[0058] An invalid level is input to the first control terminal, and a valid level is input to the second control terminal. The voltage applied to the gate of the source follower transistor changes based on the size of the light-sensitive voltage, and controls the second electrode of the source follower transistor to output different detection currents. Specifically, at this time, the voltage of the N1 node becomes VDD, and the adjustment amplitude of its voltage is (VDD-Vpin). The N2 node is in a suspended state. Coupled by the voltage of the N1 node, the voltage change of the N2 node should be the same as the voltage change of the N1 node, that is, the voltage of the N2 node is increased by (VDD-Vpin) on the basis of the original compensation voltage. At this time, the voltage of the N2 node is (VDD+Vth+VDD-Vpin), that is, the voltage written on the gate of M3 at this time is (VDD+Vth+VDD-Vpin). At this time, the Vth compensation of the source follower transistor M3 can be realized through the photoelectric detection circuit provided in the first embodiment, so that the input detection current value is not affected by the threshold voltage, thereby improving the uniformity and accuracy of the circuit output result.

[0059] In the case where a reset circuit is included in the photodetection circuit, such as Figure 8 As shown, before the execution of stage t1, a reset stage (t0) is also included. At this time, the first control terminal and the second control terminal both input invalid levels, and the third control terminal inputs a valid level. The reset circuit resets the photosensitive element and the compensation circuit based on the control of the first reset voltage terminal and the second reset voltage terminal.

[0060] This embodiment drives the photoelectric detection circuit provided by the first embodiment to compensate for the threshold voltage of the source follower transistor, thereby eliminating the influence of the threshold voltage of the source follower transistor on the output current during use, thereby improving the detection uniformity and accuracy of the photoelectric detection circuit.

[0061] The third embodiment of the present disclosure provides a photoelectric sensor, which at least includes the photoelectric detection circuit provided in the first embodiment of the present disclosure, and is mainly used for image recognition, for example, as a CMOS, CCD image sensor array, or as a detection sensor for fingerprint, palm print, facial recognition detection, etc. in smart devices. In particular, in image sensors for glass substrates, by setting the photoelectric sensor provided in this embodiment, accurate detection of light can be achieved, thereby improving the detection accuracy of the sensor.

[0062] In actual implementation, the number of photoelectric detection circuits included in the photoelectric sensor will be set to multiple according to the setting of pixels, and the multiple photoelectric detection circuits will be designed and implemented in an array arrangement. Fig. 9 A schematic diagram of a photoelectric sensor array is shown, in which the photoelectric detection circuit connected is Figure 7 The photoelectric detection circuit shown, Fig. 9A total of four photoelectric detection circuits arranged in a 2*2 array are shown. In actual implementation, array arrangements of different sizes can be set according to the size of the photoelectric sensor and actual needs to achieve accurate detection of the light intensity in the area corresponding to the photoelectric sensor.

[0063] In addition, if Fig. 9 As shown, the photoelectric sensor also includes a peripheral processing circuit, which is connected to the output end of each photoelectric detection circuit in the photoelectric sensor array to amplify and perform calculations on the induced current output by the photoelectric detection circuit. The specific model that can be selected or the function that can be achieved can be adjusted according to actual conditions, and this embodiment does not limit it.

[0064] Multiple embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications to the embodiments based on the concepts of the present disclosure, and these variations and modifications should all fall within the scope of protection required by the present disclosure.

Claims

1. A photoelectric detection circuit, characterized in that: include: A photosensitive element, a source follower transistor and a compensation circuit; wherein, The compensation circuit is connected to the first electrode of the photosensitive element, the first electrode of the source follower transistor, the gate of the source follower transistor, the first control terminal and the second control terminal, and the first electrode of the source follower transistor is also connected to the working voltage; The compensation circuit is configured to: obtain the threshold voltage of the source follower transistor under the control of the first control terminal and the second control terminal, and form a compensation voltage input to the gate of the source follower transistor according to the operating voltage and the threshold voltage.

2. The photoelectric detection circuit according to claim 1, characterized in that: The compensation circuit at least comprises: a first transistor, a second transistor, a fourth transistor and a first capacitor; wherein, The first electrode of the first transistor is connected to the first electrode of the photosensitive element, the second electrode of the first transistor is connected to the second electrode of the fourth transistor and the first electrode of the first capacitor, the gate of the first transistor is connected to the first control terminal, the first electrode of the fourth transistor is connected to the operating voltage, the second electrode of the fourth transistor is connected to the second control terminal, the second electrode of the first capacitor is connected to the gate of the source follower transistor and the second electrode of the second transistor, the first electrode of the second transistor is connected to the second electrode of the source follower transistor, and the gate of the second transistor is connected to the first control terminal.

3. The photoelectric detection circuit according to claim 2, characterized in that: When a valid level is input to the first control terminal and an invalid level is input to the second control terminal, the compensation circuit inputs the compensation voltage to the gate of the source follower transistor; When an invalid level is input to the first control terminal and a valid level is input to the second control terminal, the voltage applied to the first electrode of the first capacitor is adjusted to the working voltage by the photosensitivity voltage output by the photosensitive element, and the voltage applied to the gate of the source follower transistor is adjusted according to the voltage adjustment amplitude of the first electrode of the first capacitor, so that the induced current output by the second electrode of the source follower transistor is adjusted based on the size of the photosensitivity voltage output by the photosensitive element.

4. The photoelectric detection circuit according to claim 1, characterized in that: Also includes: A row gate tube, wherein the first electrode of the row gate tube is connected to the second electrode of the source follower transistor, the gate of the row gate tube is connected to the second control terminal, and the second electrode of the row gate tube is used to output the detection current output by the source follower transistor.

5. The photoelectric detection circuit according to claim 2, characterized in that: Also includes: Reset circuit; The reset circuit is connected to the photosensitive element, the compensation circuit, a first reset voltage terminal, a second reset voltage terminal and a third control terminal; The reset circuit is configured to reset the photosensitive element and the compensation circuit according to control of the third control terminal, the first reset voltage terminal, and the second reset voltage terminal.

6. The photoelectric detection circuit according to claim 5, characterized in that: The reset circuit at least comprises: a sixth transistor, a seventh transistor and an eighth transistor; wherein, The first electrode of the sixth transistor is connected to the first reset voltage terminal, the second electrode of the sixth transistor is connected to the first electrode of the first capacitor, the gate of the sixth transistor is connected to the third control terminal, the first electrode of the seventh transistor is connected to the first electrode of the photosensitive element, the second electrode of the seventh transistor is connected to the first reset voltage terminal, the gate of the seventh transistor is connected to the third control terminal, the first electrode of the eighth transistor is connected to the second reset voltage terminal, the second electrode of the eighth transistor is connected to the second electrode of the first capacitor, and the gate of the eighth transistor is connected to the third control terminal.

7. A driving method of a photoelectric detection circuit according to any one of claims 1 to 6, characterized in that: include: Phase 1: Invalid levels are input to the first control terminal and the second control terminal, and the photosensitive element collects photocharges; Phase 2: The first control terminal inputs a valid level, the second control terminal inputs an invalid level, the photosensitive element outputs a photosensitive voltage, and the compensation circuit obtains the threshold voltage of the source follower transistor under the drive of the valid level, and forms a compensation voltage according to the working voltage and the threshold voltage to input to the gate of the source follower transistor; Phase 3: The first control terminal inputs an invalid level, the second control terminal inputs a valid level, the voltage applied to the gate of the source follower transistor changes based on the magnitude of the light-sensing voltage, and controls the second electrode of the source follower transistor to output different detection currents.

8. The driving method according to claim 7, characterized in that: In the case where the photoelectric detection circuit includes a reset circuit, before the first stage is performed, the method further includes: Reset phase: The first control terminal and the second control terminal both input invalid levels, and the third control terminal inputs valid levels. The reset circuit resets the photosensitive element and the compensation circuit based on the control of the first reset voltage terminal and the second reset voltage terminal.

9. A photoelectric sensor, characterized in that: At least comprising the photoelectric detection circuit according to any one of claims 1 to 6.

10. The photoelectric sensor according to claim 9, characterized in that: The photoelectric sensor at least includes a plurality of the photoelectric detection circuits arranged in an array.

11. The photoelectric sensor according to claim 9 or 10, characterized in that: Also includes: A peripheral processing circuit is connected to the output end of the photoelectric detection circuit and is used to amplify and perform calculation processing on the induced current output by the photoelectric detection circuit.

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