Photoelectric sensor pixel compensation circuit, driving method and display device

Abstract

The present invention discloses a photoelectric sensor pixel compensation circuit, a driving method and a display device. The photoelectric sensor pixel compensation circuit includes a first switch control module, a driving module, a second switch control module, an energy storage module and a photoelectric conversion module; the first switch control module is configured to reset the potential of the first node in the reset phase and write the threshold voltage of the driving transistor into the first node; the driving module is configured to generate a current signal in response to the voltage signal of the first node; the second switch control module is configured to output the current signal generated by the driving module to the signal reading end in the data reading phase; the energy storage module is configured to store the voltage difference information between the first node and the third node; the photoelectric conversion module is configured to receive the light signal and convert the light signal into an electrical signal. The output current of the photoelectric sensor pixel compensation circuit provided in this article is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the field of display technology, and in particular to a photoelectric sensor pixel compensation circuit, a driving method and a display device. Background Art

[0002] APS (Active Pixel Sensor) circuits are commonly found in the design of CMOS (Complementary Metal Oxide Semiconductor) image sensors and can also be used in the design of detection circuits for photoelectric sensors. APS circuits have higher signal amplification capabilities than PPS (Passive Pixel Sensor) circuits and therefore have higher noise immunity.

[0003] APS circuits generally include a photodetector and multiple transistors, one of which is a driving transistor and the other transistors are switching transistors. Under the action of light, the photodetector (such as a photodiode) generates a photocurrent, and one end of the photodetector is connected to the control electrode (gate electrode) of the driving transistor, causing a change in the voltage of the control electrode (gate electrode) of the driving transistor. The driving transistor stably converts the voltage of the control electrode into a current flowing through the driving transistor, thereby amplifying the current generated by the photodetector.

[0004] For a substrate including a plurality of APS circuits, since the threshold voltages of the driving transistors of different APS circuits are different, the currents flowing through the driving transistors are different, thereby causing uneven pixel brightness. Summary of the invention

[0005] In a first aspect, the present disclosure provides a photoelectric sensor pixel compensation circuit, comprising: a first switch control module, a driving module, a second switch control module, an energy storage module and a photoelectric conversion module; the driving module comprises a driving transistor;

[0006] A first switch control module, connected to the first control signal terminal, the first node and the second node respectively, configured to reset the potential of the first node in a reset phase in response to a first control signal provided by the first control signal terminal, and write the threshold voltage of the driving transistor into the first node;

[0007] A driving module, connected to the first node, the second node and the third node respectively, configured to generate a current signal in response to a voltage signal of the first node; the third node is also connected to the first power signal terminal;

[0008] A second switch control module, connected to the second control signal terminal, the second node and the signal reading terminal respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a second control signal provided by the second control signal terminal;

[0009] an energy storage module, connected to the first node and the third node respectively, and configured to store voltage difference information between the first node and the third node;

[0010] The photoelectric conversion module is connected to the first reference signal terminal and the first node respectively, and is configured to receive an optical signal and convert the optical signal into an electrical signal.

[0011] In a second aspect, the present disclosure provides a photoelectric sensor pixel compensation circuit, including: a first switch control module, a second switch control module, a third switch control module, a fourth switch control module, a driving module, an energy storage module and a photoelectric conversion module; the driving module includes a driving transistor;

[0012] A first switch control module, connected to the first control signal terminal, the first reference signal terminal and the first node, respectively, and configured to provide a first reference signal provided by the first reference signal terminal to the first node in a reset phase and an exposure phase in response to a first control signal provided by the first control signal terminal;

[0013] A second switch control module, connected to the second control signal terminal, the second reference signal terminal and the second node, respectively, and configured to provide a second reference signal provided by the second reference signal terminal to the second node in a reset phase in response to a second control signal provided by the second control signal terminal;

[0014] A third switch control module, connected to the third control signal terminal, the second node and the signal reading terminal respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a third control signal provided by the third control signal terminal;

[0015] a fourth switch control module, connected to the third control signal terminal, the third node and the first power signal terminal respectively, and configured to provide the first power signal provided by the first power signal terminal to the third node in response to a third control signal provided by the third control signal terminal during a data reading phase;

[0016] A driving module, connected to the first node, the second node and the third node respectively, configured to generate a current signal in response to a voltage difference signal between the first node and the third node;

[0017] an energy storage module, connected to the first node and the third node respectively, configured to store information of the threshold voltage of the driving transistor in a reset phase, store information of a voltage variation of the third node in an exposure phase, and write the information of the threshold voltage and the information of the voltage variation of the third node into the first node in a data reading phase;

[0018] The photoelectric conversion module is connected to the third reference signal terminal and the third node respectively, and is configured to receive the optical signal and convert the optical signal into an electrical signal.

[0019] In a third aspect, the present disclosure provides a method for driving a photoelectric sensor pixel compensation circuit, comprising the following steps:

[0020] In the reset stage, the first switch control module resets the potential of the first node under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node;

[0021] In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal, and stores the generated charge in the energy storage module to change the potential of the first node;

[0022] In the data reading stage, the driving module generates a current signal according to the voltage signal of the first node; and the second switch control module outputs the current signal to the signal reading end under the control of the second control signal.

[0023] In a fourth aspect, the present disclosure provides a driving method of a photoelectric sensor pixel compensation circuit, comprising the following steps:

[0024] In the reset stage, the first switch control module resets the potentials of the first node and the third node under the control of the first control signal, the second switch control module resets the potential of the second node under the control of the second control signal, and the energy storage module stores information on the threshold voltage of the driving transistor;

[0025] In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal to change the potential of the third node, and the energy storage module stores information on the voltage change of the third node;

[0026] In the data reading stage, the energy storage module writes the information of the threshold voltage of the driving transistor and the voltage change of the third node into the first node, and the driving module generates a current signal according to the voltage difference signal between the first node and the third node; the third switch control module outputs the current signal to the signal reading end under the control of the third control signal.

[0027] In a fifth aspect, the present disclosure provides a display device comprising the above-mentioned photoelectric sensing pixel compensation circuit.

[0028] The photoelectric sensor pixel compensation circuit, driving method and display device provided by the embodiments of the present disclosure include a first switch control module, a driving module, a second switch control module, an energy storage module and a photoelectric conversion module. The first switch control module resets the potential of the first node in a reset phase under the control of a first control signal, and writes the threshold voltage of the driving transistor into the first node. The photoelectric conversion module changes the potential of the first node after generating a photocurrent through photoelectric conversion. The driving module generates a current signal according to the voltage signal of the first node. Since the threshold voltage of the driving transistor has been pre-written into the first node, the magnitude of the current generated by the driving module is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensor pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure.

[0030] Figure 1 It is a schematic diagram of the APS circuit structure in the prior art;

[0031] Figure 2 A schematic diagram of the structure of a photoelectric sensor pixel compensation circuit provided in an embodiment of the present disclosure;

[0032] Figure 3 A schematic diagram of an equivalent circuit of a photoelectric sensor pixel compensation circuit provided in an embodiment of the present disclosure;

[0033] Figure 4 A signal timing diagram of a photoelectric sensor pixel compensation circuit provided by an embodiment of the present disclosure;

[0034] Figure 5 A schematic diagram of a driving method of a photoelectric sensor pixel compensation circuit provided by an embodiment of the present disclosure;

[0035] Figure 6 A schematic diagram of the structure of another photoelectric sensor pixel compensation circuit provided by an embodiment of the present disclosure;

[0036] Figure 7 A schematic diagram of an equivalent circuit of another photoelectric sensor pixel compensation circuit provided by an embodiment of the present disclosure;

[0037] Figure 8 A signal timing diagram of another photoelectric sensor pixel compensation circuit provided by an embodiment of the present disclosure;

[0038] Fig. 9A schematic diagram of another driving method of a photoelectric sensor pixel compensation circuit provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in detail in conjunction with the accompanying drawings below. Note that the embodiments can be implemented in multiple different forms. A person of ordinary skill in the art can easily understand the fact that the methods and contents can be transformed into various forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the contents described in the following embodiments. In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other.

[0040] In the drawings, the size of each component, the thickness of a layer, or the area is sometimes exaggerated for the sake of clarity. Therefore, one embodiment of the present disclosure is not necessarily limited to this size, and the shape and size of each component in the drawings do not reflect the true proportion. In addition, the drawings schematically show ideal examples, and one embodiment of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0041] In the present specification, ordinal numbers such as “first”, “second” and “third” are provided to avoid confusion among constituent elements, and are not intended to limit the number.

[0042] In this specification, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate, or the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this disclosure can be understood according to specific circumstances.

[0043] In this specification, a transistor refers to an element including at least three terminals: a gate electrode, a drain electrode, and a source electrode. The transistor has a channel region between a drain electrode (drain electrode terminal, drain region, or drain electrode) and a source electrode (source electrode terminal, source region, or source electrode), and current can flow through the drain electrode, the channel region, and the source electrode. Note that in this specification, the channel region refers to a region where current mainly flows.

[0044] In this specification, the first electrode may be a drain electrode and the second electrode may be a source electrode, or the first electrode may be a source electrode and the second electrode may be a drain electrode. In the case of using transistors with opposite polarities or when the direction of current changes during circuit operation, the functions of the "source electrode" and the "drain electrode" are sometimes interchanged. Therefore, in this specification, the "source electrode" and the "drain electrode" may be interchanged.

[0045] In this specification, "electrical connection" includes the case where components are connected together through an element having some electrical function. There is no particular limitation on the "element having some electrical function" as long as it can transmit and receive electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having various functions.

[0046] In this specification, "film" and "layer" may be interchanged. For example, "conductive layer" may be replaced by "conductive film". Similarly, "insulating film" may be replaced by "insulating layer".

[0047] The term "about" in the present disclosure refers to a numerical value that is not strictly limited to allow for process and measurement errors.

[0048] The transistors used in the embodiments of the present disclosure may be thin film transistors or field effect transistors or other devices with the same characteristics. In the embodiments of the present disclosure, one of the source and the drain is called the first electrode, and the other of the source and the drain is called the second electrode.

[0049] In addition, in the description of the embodiments of the present disclosure, the terms "first level" and "second level" are only used to distinguish the difference in amplitude between the two levels. When the transistor is exemplified as a P-type thin film transistor, the signal level that triggers the transistor to turn on is a low level, and when the transistor is exemplified as an N-type thin film transistor, the signal level that triggers the transistor to turn on is a high level.

[0050] In the following example, description is made on the case where the driving transistor is an N-type thin film transistor.

[0051] Figure 1 A conventional APS circuit is shown. Figure 1 As shown, the APS circuit includes three transistors, a photodetector (such as a photodiode) and a storage capacitor (optional). Transistor T1 is a reset transistor. The control electrode of transistor T1 is connected to the first control signal terminal Reset, the first electrode of T1 is connected to the first reference signal terminal Vrst, and the second electrode of T1 is connected to the first node A. Transistor T1 works in a switching state. After each photocurrent generated by the photodiode is read out, transistor T1 is turned on to reset the potential of the first node A to the voltage U of the first reference signal provided by the first reference signal terminal Vrst. Vrst, thus preparing for the next round of data reading. Transistor T2 is an amplifying transistor. The control electrode of transistor T2 is connected to the first node, the first electrode of T2 is connected to the first power signal terminal VDD, and the second electrode of T2 is connected to the first electrode of the third transistor T3. Transistor T2 works in an amplifying state. In the process of the photodiode receiving light, photoelectrons are continuously accumulated on the photodiode, causing the potential of the first node to continuously decrease. Transistor T2 stably converts the voltage of the first node into a current flowing through transistor T2. Transistor T3 works in a switching state. The control electrode of T3 is connected to the second control signal terminal Gate, the first electrode of T3 is connected to the second electrode of transistor T2, and the second electrode of T3 is used as the output end of the APS circuit to output the current Io amplified by transistor T2 to the back-end data acquisition module.

[0052] In the above conventional APS circuit, the current I output by the amplifying transistor T2 is o = k(V gs -Vth) 2 It is related to the threshold voltage Vth of the amplifier transistor. Due to the device differences of the amplifier transistors used in different APS circuits, the threshold voltages Vth of the amplifier transistors in different APS circuits are different, causing uneven pixel brightness.

[0053] The present disclosure provides a photoelectric sensor pixel compensation circuit. Figure 2 As shown, the embodiment of the present disclosure provides a photoelectric sensor pixel compensation circuit, including: a first switch control module 1, a driving module 2, a second switch control module 3, an energy storage module 4 and a photoelectric conversion module 5; the driving module 2 includes a driving transistor;

[0054] a first switch control module, connected to the first control signal terminal G1, the first node N1 and the second node N2, respectively, and configured to reset the potential of the first node in a reset phase in response to a first control signal provided by the first control signal terminal, and write the threshold voltage of the driving transistor into the first node;

[0055] A driving module, connected to the first node, the second node and the third node N3 respectively, configured to generate a current signal in response to a voltage signal of the first node; the third node is also connected to the first power signal terminal VSS;

[0056] A second switch control module, connected to the second control signal terminal G2, the second node and the signal reading terminal RD, respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a second control signal provided by the second control signal terminal;

[0057] an energy storage module, connected to the first node and the third node respectively, and configured to store voltage difference information between the first node and the third node;

[0058] The photoelectric conversion module is connected to the first reference signal terminal V1 and the first node respectively, and is configured to receive an optical signal and convert the optical signal into an electrical signal.

[0059] In the photoelectric sensing pixel compensation circuit provided by the above embodiment, the first switch control module resets the potential of the first node in the reset phase under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node. The photoelectric conversion module changes the potential of the first node after generating a photocurrent through photoelectric conversion. The driving module generates a current signal according to the voltage signal of the first node. Since the threshold voltage of the driving transistor has been pre-written into the first node, the magnitude of the current generated by the driving module is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensing pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0060] In some exemplary embodiments, the photoelectric conversion module includes a photodetector, one end of the photodetector is connected to the first node, and the other end of the photodetector is connected to the first reference signal terminal;

[0061] Wherein, the photodetector includes: a photodiode or an MSM (Metal-Semiconductor-Metal) photodetector;

[0062] Photodiodes include: PN type or PIN type photodiodes, avalanche photodiodes, etc.

[0063] In some exemplary embodiments, the photoelectric conversion module includes a photodiode D1, an anode of the photodiode is connected to the first node, and a cathode of the photodiode is connected to the first reference signal terminal;

[0064] In some exemplary embodiments, the first switch control module includes a first transistor T1; a control electrode of the first transistor T1 is connected to a first control signal terminal, a first electrode of T1 is connected to a first node, and a second electrode of T1 is connected to a second node;

[0065] In some exemplary embodiments, the driving module includes a second transistor T2; a control electrode of the second transistor T2 is connected to the first node, a first electrode of T2 is connected to the second node, and a second electrode of T2 is connected to the third node;

[0066] In some exemplary embodiments, the second switch control module includes a third transistor T3; the control electrode of the third transistor T3 is connected to the second control signal terminal, the first electrode of T3 is connected to the second node, and the second electrode of T3 is connected to the signal reading terminal;

[0067] In some exemplary embodiments, the energy storage module includes a capacitor C1; a first electrode of the capacitor C1 is connected to the first node, and a second electrode of C1 is connected to the third node.

[0068] Figure 3 An equivalent circuit diagram of a photoelectric sensor pixel compensation circuit is provided. Figure 3 As shown, the photoelectric sensing pixel compensation circuit includes: a photodiode D1, a first transistor T1, a second transistor T2, a third transistor T3 and a capacitor C1; wherein the second transistor T2 is a driving transistor, and the first transistor T1 and the second transistor T2 are switch transistors;

[0069] The anode of the photodiode D1 is connected to the first node N1, and the cathode of D1 is connected to the first reference signal terminal V1;

[0070] The control electrode of the first transistor T1 is connected to the first control signal terminal G1, the first electrode of T1 is connected to the first node N1, and the second electrode of T1 is connected to the second node N2;

[0071] The control electrode of the second transistor T2 is connected to the first node N1, the first electrode of T2 is connected to the second node N2, and the second electrode of T2 is connected to the third node N3; the third node N3 is also connected to the first power signal terminal VSS;

[0072] A first electrode of the capacitor C1 is connected to a first node N1 , and a second electrode of the capacitor C1 is connected to a third node N3 .

[0073] The following is combined with the signal timing diagram Figure 3 The working process of one working cycle of the photoelectric sensing pixel compensation circuit is described.

[0074] exist Figure 3 In the embodiment shown, transistors T1, T2 and T3 may be N-type thin film transistors. In addition, considering that the leakage current of low temperature polysilicon thin film transistors is small, all transistors may be low temperature polysilicon thin film transistors, and the thin film transistors may be bottom gate thin film transistors or top gate thin film transistors.

[0075] Figure 4 The signal timing diagram of the photoelectric sensor pixel compensation circuit when it is working is provided. Figure 4 As shown, the working process of the photoelectric sensor pixel compensation circuit can be divided into three stages. The first reference signal provided by the first reference signal terminal V1 and the first power signal provided by the first power signal terminal VSS are both DC signals, and the voltage of the first reference signal is higher than the voltage of the first power signal. The first control signal provided by the first control signal terminal G1 and the second control signal provided by the second control signal terminal G2 are both pulse signals.

[0076] (1) Phase I Figure 4 t1 phase)

[0077] The first control signal is a high level signal in the first stage, and the second control signal is a low level signal in the first stage.

[0078] In the first stage, the first control signal is a high level signal, the first transistor is turned on, the second transistor works in the diode mode, the potential of the first node is equal to the potential of the second node, and U N1 =U N2 =U VSS +V th , where V th is the threshold voltage of the driving transistor (the second transistor), U VSS is the voltage of the first power signal. The first stage can be regarded as a node (first node) reset stage, that is, the potential of the first node is reset, and the threshold voltage of the driving transistor is written into the first node.

[0079] In the first stage, the second control signal is a low level signal, the third transistor is in a cut-off state, and the signal reading terminal RD does not output a current signal.

[0080] (2) Second stage Figure 4 t2 phase)

[0081] The first control signal is a low level signal in the second stage, and the second control signal is a low level signal in the second stage.

[0082] In the second stage, the first transistor and the third transistor are both turned off. The voltage of the first reference signal is higher than the voltage of the first node, so the photodiode is in a reverse bias state. The photodiode receives the optical signal and converts the optical signal into an electrical signal. The potential of the first node is raised by ΔU in the second stage, U N1 =U VSS +V th +ΔU. The second stage can be regarded as the photoelectric conversion stage of the photodiode, that is, the exposure stage.

[0083] In the second stage, the third transistor is in a cut-off state, and the signal reading terminal RD does not output a current signal.

[0084] (3) The third stage Figure 4 t3 stage)

[0085] The first control signal is a low level signal in the third stage, and the second control signal is a high level signal in the third stage.

[0086] In the third stage, the driving transistor generates a current I according to the voltage signal of the first node. o, I o = k(V gs -Vth) 2 ; k is a parameter related to the process parameters and feature size of the driving transistor;

[0087] V gs =U N1 -U N3 ;

[0088] Among them, U N1 =U VSS +V th +ΔU;U N3 =U VSS ;

[0089] Therefore, V gs =(U VSS +V th +ΔU)-U VSS =V th +ΔU;

[0090] I o = k(V gs -Vth) 2 = k(V th +ΔU-V th ) 2 =k(ΔU) 2 ;

[0091] In the third stage, the third transistor is turned on, and the signal reading terminal RD outputs a current signal I o The current magnitude of the current signal has nothing to do with the threshold voltage of the driving transistor. The third stage can be regarded as a stage for reading current data.

[0092] The working process of the photoelectric sensor pixel compensation circuit can be divided into three stages: the first stage is the reset stage of the node (first node) potential, in which the threshold voltage of the driving transistor is written into the first node. The second stage is the exposure stage of the photoelectric conversion element, and the third stage is the stage of reading current data.

[0093] In the photoelectric sensing pixel compensation circuit of the disclosed embodiment, in the reset stage, the first transistor resets the potential of the first node under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node. In the exposure stage, the photoelectric conversion element generates an electrical signal through photoelectric conversion and raises the potential of the first node. In the data reading stage, the driving transistor generates a current signal according to the voltage signal of the first node. Since the threshold voltage of the driving transistor has been pre-written into the first node, the magnitude of the current generated by the driving transistor is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensing pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0094] The embodiment of the present disclosure provides a driving method of a photoelectric sensor pixel compensation circuit, which may include the following steps:

[0095] In the reset stage, the first switch control module resets the potential of the first node under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node;

[0096] In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal, and stores the generated charge in the energy storage module to change the potential of the first node;

[0097] In the data reading stage, the driving module generates a current signal according to the voltage signal of the first node; and the second switch control module outputs the current signal to the signal reading end under the control of the second control signal.

[0098] The driving method of the photoelectric sensing pixel compensation circuit of the embodiment of the present disclosure is that in the reset stage, the first switch control module resets the potential of the first node under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node. In the exposure stage, the photoelectric conversion module receives the light signal and converts the light signal into an electrical signal, and stores the generated charge in the energy storage module to raise the potential of the first node. In the data reading stage, the driving module generates a current signal according to the voltage signal of the first node; the second switch control module outputs the current signal to the signal reading end under the control of the second control signal. Since the threshold voltage of the driving transistor has been pre-written to the first node, the magnitude of the current generated by the driving module is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensing pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0099] In some exemplary embodiments, the driving module generates a current signal according to a voltage signal of the first node, including:

[0100] The current value I of the current signal generated by the driving module according to the voltage signal of the first node o for:

[0101] I o =k(ΔU) 2 ;

[0102] Wherein, k is a parameter related to the process parameters and feature size of the driving transistor; ΔU is the voltage change of the first node caused by the photoelectric conversion effect of the photoelectric conversion module during the exposure stage.

[0103] The present disclosure provides a photoelectric sensor pixel compensation circuit. Figure 6 As shown, the embodiment of the present disclosure provides a photoelectric sensor pixel compensation circuit, including: a first switch control module 1, a second switch control module 2, a third switch control module 3, a fourth switch control module 4, a driving module 5, an energy storage module 6 and a photoelectric conversion module 7; the driving module 5 includes a driving transistor;

[0104] A first switch control module, connected to the first control signal terminal G1, the first reference signal terminal V1 and the first node N1, respectively, and configured to provide a first reference signal provided by the first reference signal terminal to the first node in a reset phase and an exposure phase in response to a first control signal provided by the first control signal terminal;

[0105] A second switch control module, connected to the second control signal terminal G2, the second reference signal terminal V2 and the second node N2 respectively, configured to provide a second reference signal provided by the second reference signal terminal to the second node in a reset phase in response to a second control signal provided by the second control signal terminal;

[0106] A third switch control module, connected to the third control signal terminal G3, the second node and the signal reading terminal RD, respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a third control signal provided by the third control signal terminal;

[0107] a fourth switch control module, connected to the third control signal terminal G3, the third node N3 and the first power signal terminal VSS respectively, and configured to provide the first power signal provided by the first power signal terminal to the third node in response to a third control signal provided by the third control signal terminal during a data reading phase;

[0108] A driving module, connected to the first node, the second node and the third node N3 respectively, configured to generate a current signal in response to a voltage difference signal between the first node and the third node;

[0109] an energy storage module, connected to the first node and the third node respectively, configured to store information of the threshold voltage of the driving transistor in a reset phase, store information of a voltage variation of the third node in an exposure phase, and write the information of the threshold voltage and the information of the voltage variation of the third node into the first node in a data reading phase;

[0110] The photoelectric conversion module is connected to the third reference signal terminal V3 and the third node respectively, and is configured to receive the optical signal and convert the optical signal into an electrical signal.

[0111] In the photoelectric sensor pixel compensation circuit provided in the above embodiment, the first switch control module provides the first reference signal to the first node in the reset stage and the exposure stage under the control of the first control signal, the second switch control module provides the second reference signal to the second node in the reset stage under the control of the second control signal, the fourth switch control module provides the first power supply signal to the third node in the data reading stage under the control of the third control signal, the photoelectric conversion module generates an electrical signal to change the potential of the third node through photoelectric conversion, the energy storage module stores the threshold voltage information of the driving transistor in the reset stage, stores the voltage change amount information of the third node in the exposure stage, writes the threshold voltage information and the voltage change amount information of the third node into the first node in the data reading stage, the driving module generates a current signal according to the voltage difference signal between the first node and the third node, and the third switch control module outputs the current signal generated by the driving module to the signal reading end in the data reading stage under the control of the third control signal. Since the threshold voltage of the driving transistor is pre-stored in the energy storage module and written into the first node in the data reading stage, the magnitude of the current generated by the driving module is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensor pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0112] In some exemplary embodiments, the photoelectric conversion module includes a photodetector, one end of the photodetector is connected to the first node, and the other end of the photodetector is connected to the first reference signal terminal;

[0113] The photodetector comprises: a photodiode or a metal-semiconductor-metal MSM photodetector;

[0114] Photodiodes include: PN type or PIN type photodiodes, avalanche photodiodes, etc.

[0115] In some exemplary embodiments, the photoelectric conversion module includes a photodiode D1, an anode of the photodiode is connected to the third reference signal terminal, and a cathode of the photodiode is connected to the third node;

[0116] In some exemplary embodiments, the first switch control module includes a first transistor T1; a control electrode of the first transistor T1 is connected to a first control signal terminal, a first electrode of T1 is connected to a first reference signal terminal, and a second electrode of T1 is connected to a first node;

[0117] In some exemplary embodiments, the second switch control module includes a second transistor T2; the control electrode of the second transistor T2 is connected to the second control signal terminal, the first electrode of T2 is connected to the second reference signal terminal, and the second electrode of T2 is connected to the second node;

[0118] In some exemplary embodiments, the third switch control module includes a third transistor T3; a control electrode of the third transistor T3 is connected to a third control signal terminal, a first electrode of T3 is connected to a second node, and a second electrode of T3 is connected to a signal reading terminal;

[0119] In some exemplary embodiments, the fourth switch control module includes a fourth transistor T4; a control electrode of the fourth transistor T4 is connected to the third control signal terminal, a first electrode of T4 is connected to the third node, and a second electrode of T4 is connected to the first power signal terminal;

[0120] In some exemplary embodiments, the driving module includes a fifth transistor T5; a control electrode of the fifth transistor T5 is connected to the first node, a first electrode of T5 is connected to the second node, and a second electrode of T5 is connected to the third node;

[0121] In some exemplary embodiments, the energy storage module includes a capacitor C1; a first electrode of the capacitor C1 is connected to the first node, and a second electrode of C1 is connected to the third node.

[0122] Figure 7 An equivalent circuit diagram of a photoelectric sensor pixel compensation circuit is provided. Figure 7 As shown, the photoelectric sensing pixel compensation circuit includes: a photodiode D1, a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5 and a capacitor C1; wherein the fifth transistor T5 is a driving transistor, and the first transistor T1, the second transistor T2, the third transistor T3 and the fourth transistor T4 are all switch transistors;

[0123] The anode of the photodiode is connected to the third reference signal terminal, and the cathode of the photodiode is connected to the third node;

[0124] The control electrode of the first transistor T1 is connected to the first control signal terminal, the first electrode of T1 is connected to the first reference signal terminal, and the second electrode of T1 is connected to the first node;

[0125] The control electrode of the second transistor T2 is connected to the second control signal terminal, the first electrode of T2 is connected to the second reference signal terminal, and the second electrode of T2 is connected to the second node;

[0126] The control electrode of the third transistor T3 is connected to the third control signal terminal, the first electrode of T3 is connected to the second node, and the second electrode of T3 is connected to the signal reading terminal;

[0127] The control electrode of the fourth transistor T4 is connected to the third control signal terminal, the first electrode of T4 is connected to the third node, and the second electrode of T4 is connected to the first power signal terminal;

[0128] The control electrode of the fifth transistor T5 is connected to the first node, the first electrode of T5 is connected to the second node, and the second electrode of T5 is connected to the third node;

[0129] A first electrode of the capacitor C1 is connected to the first node, and a second electrode of C1 is connected to the third node.

[0130] The following is combined with the signal timing diagram Figure 7 The working process of one working cycle of the photoelectric sensing pixel compensation circuit is described.

[0131] exist Figure 7 In the embodiment shown, transistors T1, T2, T3, T4 and T5 may be N-type thin film transistors. In addition, considering that the leakage current of low temperature polysilicon thin film transistors is small, all transistors may be low temperature polysilicon thin film transistors, and the thin film transistors may be bottom gate thin film transistors or top gate thin film transistors.

[0132] Figure 8 The signal timing diagram of the photoelectric sensor pixel compensation circuit when it is working is provided. Figure 8 As shown, the working process of the photoelectric sensor pixel compensation circuit can be divided into three stages. The first reference signal provided by the first reference signal terminal V1, the second reference signal provided by the second reference signal terminal V2, the third reference signal provided by the third reference signal terminal V3, and the first power signal provided by the first power signal terminal VSS are all DC signals. The first control signal provided by the first control signal terminal G1, the second control signal provided by the second control signal terminal G2, and the third control signal provided by the third control signal terminal G3 are all pulse signals.

[0133] (1) Phase I Figure 8 t1 phase)

[0134] The first control signal is a high level signal in the first stage, the second control signal is a high level signal in the first stage, and the third control signal is a low level signal in the first stage.

[0135] In the first stage, the first control signal and the second control signal are high level signals, and the first transistor and the second transistor are turned on. N1 For: U N1 =U V1 Among them, U V1 is the voltage of the first reference signal. The potential of the second node U N3 For: U N2 =U V2 Among them, U V2 is the voltage of the second reference signal. The driving transistor (fifth transistor) is turned on, and the potential U of the third node N3 For: U N3 =U V1 -V th ; Among them, V th is the threshold voltage of the driver transistor.

[0136] The first electrode of the capacitor C1 is connected to the first node, the second electrode of the capacitor C1 is connected to the third node N3, and the voltage difference U between the first node and the third node is GS =U N1 -U N3 =V th , that is, the capacitor C1 stores the threshold voltage information of the driving transistor.

[0137] The first stage can be regarded as a node (first node and third node) reset stage, that is, the potentials of the first node and the third node are reset, and the threshold voltage information of the driving transistor (second transistor) is stored in the capacitor C1.

[0138] In the first stage, the third control signal is a low level signal, the third transistor is in a cut-off state, and the signal reading terminal RD does not output a current signal.

[0139] (2) Second stage Figure 8 t2 phase)

[0140] The first control signal is a high level signal in the second stage, the second control signal is a low level signal in the second stage, and the third control signal is a low level signal in the second stage.

[0141] In the second stage, the first control signal is a high level signal, and the first transistor is turned on. N1 For: U N1 =U V1 The second control signal is a low level signal, and the second transistor is turned off. The potential of the third node is higher than the voltage value of the third reference signal, so the photodiode is in a reverse bias state. The photodiode receives the optical signal and converts the optical signal into an electrical signal. The potential of the third node decreases by ΔU in the second stage, U N3 =UV1 -V th -ΔU. The second stage can be regarded as the photoelectric conversion stage of the photodiode, that is, the exposure stage.

[0142] In the second stage, the third control signal is a low level signal, the third transistor is in a cut-off state, and the signal reading terminal RD does not output a current signal.

[0143] (3) The third stage Figure 8 t3 stage)

[0144] The first control signal is a low level signal in the second stage, the second control signal is a low level signal in the second stage, and the third control signal is a high level signal in the second stage.

[0145] In the third stage, the first control signal and the second control signal are low level signals, the first transistor and the second transistor are turned off, and the third control signal is a high level signal, the third transistor and the fourth transistor are turned on.

[0146] The fourth transistor is turned on, and the potential of the third node jumps. N3 =U VSS Among them, U VSS The first electrode of capacitor C1 is connected to the first node, and the second electrode of capacitor C1 is connected to the third node N3. When the potential of the third node jumps, the potential of the other electrode (first node) of capacitor C1 also jumps. Therefore, the potential of the first node becomes: U N1 =U VSS +V th +ΔU.

[0147] The driving transistor generates a current I according to the voltage difference signal between the first node and the third node. o , I o = k(V gs -Vth) 2 ; k is a parameter related to the process parameters and feature size of the driving transistor;

[0148] V gs =U N1 -U N3 ;

[0149] Among them, U N1 =U VSS +V th +ΔU;U N3 =U VSS ;

[0150] Therefore, V gs =(U VSS +V th +ΔU)-UVSS =V th +ΔU;

[0151] I o = k(V gs -Vth) 2 = k(V th +ΔU-V th ) 2 =k(ΔU) 2 ;

[0152] In the third stage, the third transistor is turned on, and the signal reading terminal RD outputs a current signal I o The current magnitude of the current signal has nothing to do with the threshold voltage of the driving transistor. The third stage can be regarded as a stage for reading current data.

[0153] The working process of the photoelectric sensing pixel compensation circuit can be divided into three stages: the first stage is the node potential reset stage, the potentials of the first node and the third node are reset, and in the reset stage, the threshold voltage of the driving transistor is stored in the capacitor. The second stage is the exposure stage of the photoelectric conversion element, the photoelectric conversion element generates an electrical signal through photoelectric conversion and lowers the potential of the third node, and the information of the voltage change amount of the third node is stored in the capacitor. The third stage is the stage of reading current data, the information of the threshold voltage and the information of the voltage change amount of the third node are written into the first node, so the magnitude of the current generated by the driving transistor is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensing pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0154] The embodiment of the present disclosure provides a driving method of a photoelectric sensor pixel compensation circuit, which may include the following steps:

[0155] In the reset stage, the first switch control module resets the potentials of the first node and the third node under the control of the first control signal, the second switch control module resets the potential of the second node under the control of the second control signal, and the energy storage module stores information on the threshold voltage of the driving transistor;

[0156] In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal to change the potential of the third node, and the energy storage module stores information on the voltage change of the third node;

[0157] In the data reading stage, the energy storage module writes the information of the threshold voltage of the driving transistor and the voltage change of the third node into the first node, and the driving module generates a current signal according to the voltage difference signal between the first node and the third node; the third switch control module outputs the current signal to the signal reading end under the control of the third control signal.

[0158] The driving method of the photoelectric sensor pixel compensation circuit of the embodiment of the present disclosure, in the reset stage, the first switch control module resets the potential of the first node and the third node under the control of the first control signal, the second switch control module resets the potential of the second node under the control of the second control signal, and the energy storage module stores the threshold voltage information of the driving transistor. In the exposure stage, the photoelectric conversion module receives the light signal and converts the light signal into an electrical signal to change the potential of the third node, and the energy storage module stores the information of the voltage change amount of the third node. In the data reading stage, the energy storage module writes the information of the threshold voltage of the driving transistor and the information of the voltage change amount of the third node into the first node, and the driving module generates a current signal according to the voltage difference signal between the first node and the third node; the third switch control module outputs the current signal to the signal reading end under the control of the third control signal. Since the threshold voltage of the driving transistor has been pre-written into the first node, the magnitude of the current generated by the driving module is independent of the threshold voltage of the driving transistor, so that the output current of the photoelectric sensor pixel compensation circuit is not affected by the threshold voltage of the driving transistor, thereby avoiding uneven brightness when multiple pixels are imaged.

[0159] In some exemplary embodiments, the driving module generates a current signal according to a voltage difference signal between the first node and the third node, including:

[0160] The current value I of the current signal generated by the driving module according to the voltage difference signal between the first node and the third node o for:

[0161] I o =k(ΔU) 2 ;

[0162] Wherein, k is a parameter related to the process parameters and feature size of the driving transistor; ΔU is the voltage change of the third node caused by the photoelectric conversion effect of the photoelectric conversion module during the exposure stage.

[0163] The embodiment of the present disclosure also provides a display device, including the above-mentioned photoelectric sensor pixel compensation circuit.

[0164] The display device may be an organic light-emitting display device. The display device may be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, etc. Other essential components of the display device should be understood by a person skilled in the art, and will not be described in detail here, nor should they be used as a limitation to the present disclosure.

[0165] Although the embodiments disclosed in the present disclosure are as above, the contents described are only embodiments adopted to facilitate understanding of the present disclosure and are not intended to limit the present disclosure. Any technician in the field to which the present disclosure belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present disclosure, but the scope of patent protection of the present disclosure shall still be subject to the scope defined in the attached claims.

Claims

1. A photoelectric sensor pixel compensation circuit, comprising: A first switch control module, a drive module, a second switch control module, an energy storage module and a photoelectric conversion module; The driving module includes a driving transistor; A first switch control module, connected to the first control signal terminal, the first node and the second node respectively, configured to reset the potential of the first node in a reset phase in response to a first control signal provided by the first control signal terminal, and write the threshold voltage of the driving transistor into the first node; a driving module, connected to the first node, the second node and the third node respectively, and configured to generate a current signal in response to a voltage signal of the first node; The third node is also connected to the first power signal terminal; A second switch control module, connected to the second control signal terminal, the second node and the signal reading terminal respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a second control signal provided by the second control signal terminal; an energy storage module, connected to the first node and the third node respectively, and configured to store voltage difference information between the first node and the third node; an optical-to-electrical conversion module, connected to the first reference signal terminal and the first node, respectively, and configured to receive an optical signal and convert the optical signal into an electrical signal; The driving module includes a second transistor T2; the control electrode of the second transistor T2 is connected to the first node, the first electrode of T2 is connected to the second node, and the second electrode of T2 is connected to the third node; The photoelectric conversion module includes a photodiode, an anode of the photodiode is connected to the first node, and a cathode of the photodiode is connected to the first reference signal terminal.

2. The photoelectric sensor pixel compensation circuit according to claim 1, characterized in that: The first switch control module includes a first transistor; the control electrode of the first transistor T1 is connected to the first control signal terminal, the first electrode of T1 is connected to the first node, and the second electrode of T1 is connected to the second node; The second switch control module includes a third transistor T3; a control electrode of the third transistor T3 is connected to the second control signal terminal, a first electrode of T3 is connected to the second node, and a second electrode of T3 is connected to the signal reading terminal.

3. The photoelectric sensor pixel compensation circuit according to claim 1, wherein: The energy storage module includes a capacitor C1; a first electrode of the capacitor C1 is connected to a first node, and a second electrode of C1 is connected to a third node.

4. The photoelectric sensor pixel compensation circuit according to claim 1, wherein: The first control signal provided by the first control signal terminal is a pulse signal; the second control signal provided by the second control signal terminal is a pulse signal.

5. A photoelectric sensor pixel compensation circuit, comprising: A first switch control module, a second switch control module, a third switch control module, a fourth switch control module, a drive module, an energy storage module and a photoelectric conversion module; the drive module includes a drive transistor; A first switch control module, connected to the first control signal terminal, the first reference signal terminal and the first node, respectively, and configured to provide a first reference signal provided by the first reference signal terminal to the first node in a reset phase and an exposure phase in response to a first control signal provided by the first control signal terminal; A second switch control module, connected to the second control signal terminal, the second reference signal terminal and the second node, respectively, and configured to provide a second reference signal provided by the second reference signal terminal to the second node in a reset phase in response to a second control signal provided by the second control signal terminal; A third switch control module, connected to the third control signal terminal, the second node and the signal reading terminal respectively, and configured to output the current signal generated by the driving module to the signal reading terminal in a data reading phase in response to a third control signal provided by the third control signal terminal; a fourth switch control module, connected to the third control signal terminal, the third node and the first power signal terminal respectively, and configured to provide the first power signal provided by the first power signal terminal to the third node in response to a third control signal provided by the third control signal terminal during a data reading phase; A driving module, connected to the first node, the second node and the third node respectively, and configured to generate a current signal in response to a voltage difference signal between the first node and the third node; an energy storage module, connected to the first node and the third node respectively, configured to store information of the threshold voltage of the driving transistor in a reset phase, store information of a voltage variation of the third node in an exposure phase, and write the information of the threshold voltage and the information of the voltage variation of the third node into the first node in a data reading phase; The photoelectric conversion module is connected to the third reference signal terminal and the third node respectively, and is configured to receive the optical signal and convert the optical signal into an electrical signal.

6. The photoelectric sensor pixel compensation circuit according to claim 5, characterized in that: The first switch control module includes a first transistor T1; the control electrode of the first transistor T1 is connected to the first control signal terminal, the first electrode of T1 is connected to the first reference signal terminal, and the second electrode of T1 is connected to the first node; The second switch control module includes a second transistor T2; the control electrode of the second transistor T2 is connected to the second control signal terminal, the first electrode of T2 is connected to the second reference signal terminal, and the second electrode of T2 is connected to the second node; The third switch control module comprises a third transistor T3; the control electrode of the third transistor T3 is connected to the third control signal terminal, the first electrode of T3 is connected to the second node, and the second electrode of T3 is connected to the signal reading terminal; The fourth switch control module includes a fourth transistor T4; the control electrode of the fourth transistor T4 is connected to the third control signal terminal, the first electrode of T4 is connected to the third node, and the second electrode of T4 is connected to the first power signal terminal; The driving module includes a fifth transistor T5; the control electrode of the fifth transistor T5 is connected to the first node, the first electrode of T5 is connected to the second node, and the second electrode of T5 is connected to the third node; The energy storage module includes a capacitor C1; a first electrode of the capacitor C1 is connected to a first node, and a second electrode of C1 is connected to a third node.

7. The photoelectric sensor pixel compensation circuit according to claim 5, characterized in that: The photoelectric conversion module comprises a photodetector, one end of the photodetector is connected to the third node, and the other end of the photodetector is connected to the third reference signal end; The photodetector includes: a photodiode or a metal-semiconductor-metal MSM photodetector.

8. A method for driving the photoelectric sensor pixel compensation circuit according to any one of claims 1 to 4, comprising the following steps: In the reset stage, the first switch control module resets the potential of the first node under the control of the first control signal, and writes the threshold voltage of the driving transistor into the first node; In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal, and stores the generated charge in the energy storage module to change the potential of the first node; In the data reading phase, the driving module generates a current signal according to the voltage signal of the first node; The second switch control module outputs the current signal to the signal reading end under the control of the second control signal; The driving module generates a current signal according to the voltage signal of the first node, including: The current value I of the current signal generated by the driving module according to the voltage signal of the first node o for: AND o =k(ΔU) 2 ; Wherein, k is a parameter related to the process parameters and feature size of the driving transistor; ΔU is the voltage change of the first node caused by the photoelectric conversion effect of the photoelectric conversion module during the exposure stage.

9. A method for driving the photoelectric sensor pixel compensation circuit according to any one of claims 5 to 7, comprising the following steps: In the reset stage, the first switch control module resets the potentials of the first node and the third node under the control of the first control signal, the second switch control module resets the potential of the second node under the control of the second control signal, and the energy storage module stores information on the threshold voltage of the driving transistor; In the exposure phase, the photoelectric conversion module receives the optical signal and converts the optical signal into an electrical signal to change the potential of the third node, and the energy storage module stores information on the voltage change of the third node; In the data reading stage, the energy storage module writes information about the threshold voltage of the driving transistor and information about the voltage change of the third node into the first node, and the driving module generates a current signal according to a voltage difference signal between the first node and the third node; The third switch control module outputs the current signal to the signal reading end under the control of the third control signal.

10. The driving method according to claim 9, characterized in that: The driving module generates a current signal according to a voltage difference signal between the first node and the third node, including: The current value I of the current signal generated by the driving module according to the voltage difference signal between the first node and the third node o for: AND o =k(ΔU) 2 ; Wherein, k is a parameter related to the process parameters and feature size of the driving transistor; ΔU is the voltage change of the third node caused by the photoelectric conversion effect of the photoelectric conversion module during the exposure stage.

11. A display device, comprising the photoelectric sensor pixel compensation circuit according to any one of claims 1 to 4, or comprising the photoelectric sensor pixel compensation circuit according to any one of claims 5 to 7.

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