Power supply voltage control circuit, pixel circuit, drive circuit and display panel

Abstract

The present application provides a power supply voltage control circuit, a pixel circuit, a driving circuit and a display panel, wherein the power supply voltage control circuit includes a first voltage gating circuit, a second voltage gating circuit and a control unit. The first voltage gating circuit is used to select and output one of the first power supply voltage and the second power supply voltage to the driving voltage input terminal of the pixel unit. The second voltage gating circuit is used to select and output one of the first power supply voltage and the second power supply voltage to the reference voltage input terminal of the pixel unit. The control unit is used to control the first voltage gating circuit to output the second power supply voltage and control the second voltage gating circuit to output the first power supply voltage when the display panel performs a shutdown operation, so as to provide a reverse bias voltage for the pixel unit to weaken or eliminate the built-in electric field of the light-emitting element of the pixel unit. The power supply voltage control circuit provided in the present application can weaken or eliminate the built-in electric field of the light-emitting element and extend the service life of the display panel.

Description

Technical Field

[0001] The present application relates to the technical field of display panels, and in particular to a power supply voltage control circuit, a pixel circuit, a driving circuit and a display panel. Background Art

[0002] OLED (Organic Light-Emitting Diode), also known as organic electric laser display and organic light-emitting semiconductor. OLED is a current-type organic light-emitting device, which emits light through the injection and recombination of carriers. The luminous intensity is proportional to the injected current. OLED display panels have the advantages of no blue light hazards, soft light, flexible foldability, no flicker, and high color quality. They have gradually become one of the mainstream display panels on the market.

[0003] Most of the light-emitting elements in the existing OLED display panels use DC drive, which has the disadvantage of easy aging. Specifically, the reasons for the aging of the light-emitting elements in the DC-driven OLED display panel are as follows: the transmission direction of holes and electrons in the light-emitting element is fixed. They are injected from the positive and negative electrodes into the light-emitting layer respectively, forming excitons in the light-emitting layer, and radiating light. Among them, the excess holes (or electrons) that do not participate in the recombination, part of them accumulate at the hole transport layer / light-emitting layer (or light-emitting layer / electron transport layer) interface, and part of them cross the potential barrier and flow into the electrode. With the extension of the use time, many uncombined carriers accumulated at the internal interface of the light-emitting layer form a built-in electric field inside the light-emitting element, which causes the threshold voltage of the light-emitting element to continue to increase, and its luminous brightness will continue to decrease, and the energy utilization efficiency will also gradually decrease. Summary of the invention

[0004] In view of this, the main purpose of the present application is to propose a power supply voltage control circuit, a pixel circuit, a drive circuit and a display panel, aiming to solve the problem that the light-emitting elements in the existing DC-driven OLED display panel are prone to aging.

[0005] The present application proposes a power supply voltage control circuit, which is used to provide a first power supply voltage and a second power supply voltage for a pixel unit in a display panel. The pixel unit includes a driving voltage input terminal, a reference voltage input terminal and a light-emitting element, the anode of the light-emitting element is electrically connected to the driving voltage input terminal, the cathode of the light-emitting element is electrically connected to the reference voltage input terminal, and the first power supply voltage is higher than the second power supply voltage. The power supply voltage control circuit includes a first voltage gating circuit, a second voltage gating circuit and a control unit. The first voltage gating circuit is used to receive and select one of the first power supply voltage and the second power supply voltage to output to the driving voltage input terminal of the pixel unit. The second voltage gating circuit is used to receive and select one of the first power supply voltage and the second power supply voltage to output to the reference voltage input terminal of the pixel unit. The control unit is electrically connected to the first voltage gating circuit and the second voltage gating circuit respectively. The control unit is used to control the first voltage gating circuit to output the first power supply voltage and the second voltage gating circuit to output the second power supply voltage when the display panel is in the working state, thereby providing a forward bias voltage for the pixel unit, so that the light-emitting element of the pixel unit can emit light based on the forward bias voltage. The control unit is also used to control the first voltage gating circuit to output the second power supply voltage and the second voltage gating circuit to output the first power supply voltage when the display panel performs a shutdown operation, thereby providing a reverse bias voltage for the pixel unit to weaken or eliminate the built-in electric field of the light-emitting element of the pixel unit.

[0006] The power supply voltage control circuit provided in the present application controls the first voltage gating circuit to output the second power supply voltage and controls the second voltage gating circuit to output the first power supply voltage through the control unit when the display panel performs a shutdown operation, thereby providing a reverse bias voltage for the pixel unit, so that the uncombined excess holes or electrons in the light-emitting unit of each light-emitting element change their movement direction and move in the opposite direction, thereby relatively consuming the uncombined electrons and holes accumulated on the interface inside the light-emitting layer, thereby weakening or eliminating the built-in electric field formed inside the light-emitting element by the excess carriers in the working state, thereby improving the stability of the light-emitting brightness, improving the energy utilization efficiency, and extending the service life of the display panel.

[0007] Optionally, the control unit is used to detect whether the display panel is in an operating state, and output a first control signal when the display panel is in an operating state, and detect whether the display panel is performing a shutdown operation, and output a second control signal when the display panel performs a shutdown operation. The first voltage gating circuit outputs a first power supply voltage in response to the first control signal, and outputs a second power supply voltage in response to the second control signal. The second voltage gating circuit outputs a second power supply voltage in response to the first control signal, and outputs a first power supply voltage in response to the second control signal.

[0008] Optionally, the display panel further includes a power module, the power module is used to output a data power voltage when the display panel is in a working state, and stop outputting the data power voltage when the display panel performs a shutdown operation. The control unit includes a comparator, the comparator is electrically connected to the power module, the comparator is used to receive the data power voltage, and compare the data power voltage with a preset reference voltage, and determine that the display panel is in a working state and output the first control signal when the data power voltage is higher than the preset reference voltage, and determine that the display panel is performing a shutdown operation and output the second control signal when the data power voltage is lower than the preset reference voltage.

[0009] Optionally, the power supply voltage control circuit further includes a first voltage input terminal, a second voltage input terminal, a first voltage output terminal and a second voltage output terminal. The first voltage input terminal is used to receive the first power supply voltage. The second voltage input terminal is used to receive the second power supply voltage. The first voltage output terminal is electrically connected to the driving voltage input terminal of the pixel unit. The second voltage output terminal is electrically connected to the reference voltage input terminal of the pixel unit. The first voltage gating circuit includes a first switch tube and a second switch tube. The first switch tube is electrically connected between the first voltage input terminal and the first voltage output terminal. The second switch tube is electrically connected between the second voltage input terminal and the first voltage output terminal. The second voltage gating circuit includes a third switch tube and a fourth switch tube. The third switch tube is electrically connected between the first voltage input terminal and the second voltage output terminal. The fourth switch tube is electrically connected between the second voltage input terminal and the second voltage output terminal. The control terminals of the first switch tube and the fourth switch tube are both electrically connected to the control unit, and are both turned on in response to the first control signal. The second switch tube and the third switch tube are both electrically connected to the control unit, and are both turned on in response to the second control signal.

[0010] Optionally, the non-inverting input terminal of the comparator is used to receive the preset reference voltage, and the inverting input terminal of the comparator is used to receive the data power supply voltage.

[0011] Optionally, the control unit further includes a storage capacitor electrically connected between the non-inverting input terminal of the comparator and the ground terminal, and the storage capacitor is used to continue to output the preset reference voltage to the non-inverting input terminal of the comparator when the display panel performs a shutdown operation.

[0012] Optionally, the first control signal is a low-level signal, the second control signal is a high-level signal, the first switch tube and the fourth switch tube are switch tubes that are turned on at a low level, and the second switch tube and the third switch tube are switch tubes that are turned on at a high level.

[0013] The embodiment of the present application also provides a pixel circuit, which is applied to a display panel, and the pixel circuit includes a pixel unit and the above-mentioned power supply voltage control circuit. The pixel unit includes a driving voltage input terminal, a reference voltage input terminal and a light-emitting element, the anode of the light-emitting element is electrically connected to the driving voltage input terminal, and the cathode of the light-emitting element is electrically connected to the reference voltage input terminal. The power supply voltage control circuit is electrically connected to the driving voltage input terminal and the reference voltage input terminal, respectively, and the power supply voltage control circuit is used to output a first power supply voltage to the driving voltage input terminal and a second power supply voltage to the reference voltage input terminal when the display panel is in a working state. The power supply voltage control circuit is also used to output a second power supply voltage to the driving voltage input terminal and a first power supply voltage to the reference voltage input terminal when the display panel performs a shutdown operation.

[0014] The embodiment of the present application also provides a driving circuit, the driving circuit is used to provide a first power supply voltage and a second power supply voltage to drive a pixel unit in a display panel, and the driving circuit includes a power supply module and the above-mentioned power supply voltage control circuit. The power supply module is used to generate the first power supply voltage and the second power supply voltage. The power supply module is electrically connected to the power supply voltage control circuit, and the power supply voltage control circuit is used to output the first power supply voltage and the second power supply voltage to the pixel unit in the display panel.

[0015] An embodiment of the present application also provides a display panel, which includes a plurality of pixel units arranged in an array and the above-mentioned driving circuit, wherein the driving circuit is electrically connected to the plurality of pixel units respectively, and the driving circuit is used to drive the corresponding pixel units to emit light when the display panel is in a working state, and to weaken or eliminate the built-in electric field of the light-emitting elements of each pixel unit when the display panel performs a shutdown operation.

[0016] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the display panel provided in the embodiment of the present application.

[0018] Figure 2 It is a structural schematic diagram of a pixel unit provided in an embodiment of the present application.

[0019] Figure 3 It is a schematic diagram of the structure of the power supply voltage control circuit provided in the embodiment of the present application.

[0020] Figure 4 It is a schematic diagram of the structure of the pixel circuit provided in an embodiment of the present application.

[0021] Description of main component symbols:

[0022] Power supply voltage control circuit 10

[0023] Pixel unit 100

[0024] Driving circuit 200

[0025] Pixel circuit 100'

[0026] Display Panel 1

[0027] Scanning signal generating circuit 110

[0028] Scan line 111

[0029] Data signal generation circuit 120

[0030] Data line 121

[0031] Power module 30

[0032] The first switch tube T1

[0033] The second switch tube T2

[0034] The third switch tube T3

[0035] The fourth switch tube T4

[0036] The first voltage input terminal VDD

[0037] The second voltage input terminal VSS

[0038] The first voltage output terminal 1011

[0039] The second voltage output terminal 1021

[0040] Drive transistor M

[0041] Scan transistor T0

[0042] Light-emitting element OLED

[0043] First voltage gating circuit 101

[0044] Second voltage gating circuit 102

[0045] Control unit 103

[0046] Comparator U1

[0047] Storage capacitor C1, Cst

[0048] Driving voltage input terminal 201

[0049] Reference voltage input terminal 202

[0050] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] In the description of the present application, it should be noted that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0053] The light-emitting element OLED generally includes an anode, a light-emitting unit and a cathode formed on a substrate. Among them, the light-emitting unit may specifically include an electron transport layer, a light-emitting layer and a hole transport layer. When a forward bias voltage is applied to the anode and the cathode, electrons can migrate from the cathode to the light-emitting layer through the electron transport layer, and holes can migrate from the anode to the light-emitting layer through the hole transport layer. The electrons and holes can form excitons after meeting and recombining in the light-emitting layer. The excitons transfer energy to the light-emitting molecules in the electroluminescent layer under the action of the electric field, so that the light-emitting molecules emit visible light.

[0054] However, most of the light-emitting elements in the existing OLED display panels use DC drive, which has the disadvantage of easy aging. Specifically, the reasons for the aging of the light-emitting elements in the DC-driven OLED display panel are as follows: the transmission direction of holes and electrons in the light-emitting element is fixed. They are injected from the positive and negative electrodes into the light-emitting layer respectively, forming excitons in the light-emitting layer, and radiating light. Among them, the excess holes (or electrons) that do not participate in the recombination, part of them accumulate at the hole transport layer / light-emitting layer (or light-emitting layer / electron transport layer) interface, and part of them cross the potential barrier and flow into the electrode. With the extension of the use time, many uncombined carriers accumulated at the internal interface of the light-emitting layer form a built-in electric field inside the light-emitting element, which causes the threshold voltage of the light-emitting element to continue to increase, and its luminous brightness will continue to decrease, and the energy utilization efficiency will gradually decrease.

[0055] See also Figure 1 In order to solve the problem that the light-emitting elements in the existing DC-driven OLED display panel are prone to aging, the embodiment of the present application provides a display panel 1, which includes a plurality of pixel units 100 and a driving circuit 200. The plurality of pixel units 100 are arranged in an array in a display area in a substrate of the display panel 1. The driving circuit 200 is electrically connected to the plurality of pixel units 100, respectively, and the driving circuit 200 is used to drive the corresponding pixel units 100 to emit light when the display panel 1 is in a working state (that is, the display panel 1 is in a powered-on state and is used to display images), and to weaken or eliminate the built-in electric field in the light-emitting elements of each pixel unit 100 when the display panel 1 performs a shutdown operation (that is, when the display panel 1 is shut down and powered off), thereby solving the problem that the light-emitting elements in the DC-driven OLED display panel are prone to aging.

[0056] Specifically, the driving circuit 200 includes a scanning signal generating circuit 110, a data signal generating circuit 120, a power supply voltage control circuit 10, and a power supply module 30. The scanning signal generating circuit 110 is electrically connected to the pixel units 100 in each row through a plurality of scanning lines 111, and the scanning signal generating circuit 110 is used to generate a corresponding plurality of scanning signals for the pixel units 100 in each row. The data signal generating circuit 120 is electrically connected to the pixel units 100 in each row through a plurality of data lines 121, and the data signal generating circuit 120 is used to generate a corresponding data voltage Vdata for each column of pixel driving circuits, and output the data voltage Vdata to each pixel unit 100 in the pixel driving circuit in the column. The power supply module 30 is used to provide power supply voltages for various circuit modules in the display panel 1, for example, providing a first power supply voltage VDD, a second power supply voltage VSS and a data power supply voltage Vsd for the power supply module 30, and providing the data power supply voltage Vsd for the data signal generating circuit 120, so that the data signal generating circuit 120 generates the data voltage Vdata based on the data power supply voltage Vsd. The power supply voltage control circuit 10 is electrically connected to the driving voltage input terminal 201 of each pixel unit 100 through its first voltage output terminal 1011, and is electrically connected to the reference voltage input terminal 202 of each pixel unit 100 through its second voltage output terminal 1021. The power supply voltage control circuit 10 is used to provide the first power supply voltage VDD and the second power supply voltage VSS for the pixel unit 100 in the display panel 1. Specifically, when the display panel 1 is in the working state, the power supply voltage control circuit 10 outputs the first power supply voltage VDD to the driving voltage input terminal 201 of each pixel unit 100 through the first voltage output terminal 1011, and outputs the second power supply voltage VSS to the reference voltage input terminal 202 of each pixel unit 100 through the second voltage output terminal 1021. When the display panel 1 performs the shutdown operation state, the power supply voltage control circuit 10 outputs the second power supply voltage VSS to the driving voltage input terminal 201 of each pixel unit 100 through the first voltage output terminal 1011, and outputs the first power supply voltage VDD to the reference voltage input terminal 202 of each pixel unit 100 through the second voltage output terminal 1021.

[0057] See also Figure 2 , Figure 2It is an existing pixel unit 100 with a 2T1C structure. Of course, in other embodiments, the pixel unit 100 may also adopt other types of circuit structures, such as 5T1C, 6T1C, 7T1C, etc. The pixel unit 100 includes the driving voltage input terminal 201, the reference voltage input terminal 202, a scanning transistor T0, a driving transistor M, a storage capacitor Cst, and a light-emitting element OLED.

[0058] The anode of the light emitting element OLED is electrically connected to the driving voltage input terminal 201, the cathode of the light emitting element OLED is electrically connected to the reference voltage input terminal 202, and the first power supply voltage VDD is higher than the second power supply voltage VSS. The pixel unit 100 can drive the light emitting element OLED to emit light.

[0059] When the display panel 1 is in working state, the cathode of the light emitting element OLED receives the second power supply voltage VSS through the reference voltage input terminal 202, and the second connection terminal of the driving transistor M receives the first power supply voltage VDD through the driving voltage input terminal 201, that is, the pixel unit 100 receives a forward bias voltage. The first connection terminal of the driving transistor M is electrically connected to the anode of the light emitting element OLED, the gate of the driving transistor M is electrically connected to the second connection terminal of the scanning transistor T0, the first connection terminal of the scanning transistor T0 is electrically connected to the data line 121 to receive the data voltage Vdata, and the gate of the scanning transistor T0 is electrically connected to the scanning line 111 to receive the scanning signal SCAN. The first end of the energy storage capacitor Cst is electrically connected to the gate of the driving transistor M, and the second end of the energy storage capacitor Cst is electrically connected to the cathode of the light emitting element OLED. Exemplarily, when the scan signal is an on signal, the scan transistor T0 is turned on, and the data voltage Vdata on the data line 121 charges the energy storage capacitor Cst through the scan transistor T0 to adjust the voltage of the first end of the energy storage capacitor Cst to the data voltage Vdata, and the driving transistor M drives the light-emitting element OLED to emit light based on the data voltage Vdata received by its gate and the first power supply voltage VDD received by its first connection end. At this time, the light-emitting element OLED enters a forward biased state, and the hole transport layer in the light-emitting unit of the light-emitting element OLED transmits holes to the light-emitting layer, and the electron transport layer in the light-emitting unit of the light-emitting element OLED transmits electrons to the light-emitting layer. After the electrons and holes meet and recombine in the light-emitting layer of the light-emitting unit, the light-emitting molecules emit visible light.

[0060] When the display panel 1 performs a shutdown operation, the cathode of the light-emitting element OLED receives the first power supply voltage VDD through the reference voltage input terminal 202, and the second connection terminal of the driving transistor M receives the second power supply voltage VSS through the driving voltage input terminal 201, that is, the pixel unit 100 receives a reverse bias voltage. The driving transistor M is continuously turned on based on the electric energy stored in the energy storage capacitor Cst, so that the light-emitting element OLED enters a reverse bias state. At this time, the light-emitting element OLED enters a reverse bias state, so that the uncombined excess holes or electrons in the light-emitting unit of the light-emitting element OLED change their movement direction and move in the opposite direction, that is, the electrons move from the light-emitting layer to the electron transport layer, and the holes move from the light-emitting layer to the hole transport layer, thereby relatively consuming the uncombined electrons and holes accumulated on the interface inside the light-emitting layer, thereby weakening or eliminating the built-in electric field formed inside the light-emitting element OLED by the excess carriers in the working state, thereby improving the stability of the light-emitting brightness, improving the energy utilization efficiency, and extending the service life of the display panel 1.

[0061] Combine the following Figure 3 The circuit structure and working principle of the power supply voltage control circuit 10 are introduced in detail. The power supply voltage control circuit 10 includes a first voltage input terminal VDD, a second voltage input terminal VSS, a first voltage output terminal 1011, a second voltage output terminal 1021, a first voltage gating circuit 101, a second voltage gating circuit 102 and a control unit 103.

[0062] The first voltage input terminal VDD is electrically connected to the power module 30, and the first voltage input terminal VDD is used to receive the first power supply voltage VDD. The second voltage input terminal VSS is also electrically connected to the power module 30, and the second voltage input terminal VSS is used to receive the second power supply voltage VSS. The first voltage output terminal 1011 is electrically connected to the driving voltage input terminal 201 of each pixel unit 100. The second voltage output terminal 1021 is electrically connected to the reference voltage input terminal 202 of each pixel unit 100.

[0063] The first voltage gating circuit 101 is electrically connected to the first voltage input terminal VDD, the second voltage input terminal VSS and the first voltage output terminal 1011 respectively, and the first voltage gating circuit 101 is used to receive and select and output one of the first power supply voltage VDD and the second power supply voltage VSS to the driving voltage input terminal 201 of each of the pixel units 100.

[0064] The second voltage gating circuit 102 is electrically connected to the first voltage input terminal VDD, the second voltage input terminal VSS and the second voltage output terminal 1021 respectively, and the second voltage gating circuit 102 is used to receive and select and output one of the first power supply voltage VDD and the second power supply voltage VSS to the reference voltage input terminal 202 of each of the pixel units 100.

[0065] The control unit 103 is electrically connected to the first voltage gating circuit 101 and the second voltage gating circuit 102, respectively. The control unit 103 is used to control the first voltage gating circuit 101 to output the first power supply voltage VDD and the second voltage gating circuit 102 to output the second power supply voltage VSS when the display panel 1 is in the working state, so as to provide a forward bias voltage for the pixel unit 100, so that the light-emitting element OLED of the pixel unit 100 can emit light based on the forward bias voltage. The control unit 103 is also used to control the first voltage gating circuit 101 to output the second power supply voltage VSS and the second voltage gating circuit 102 to output the first power supply voltage VDD when the display panel 1 performs a shutdown operation, so as to provide a reverse bias voltage for the pixel unit 100, so as to weaken or eliminate the built-in electric field of the light-emitting element OLED of the pixel unit 100.

[0066] Further, the control unit 103 is used to detect whether the display panel 1 is in an operating state, and output a first control signal when the display panel 1 is in an operating state, and detect whether the display panel 1 is performing a shutdown operation, and output a second control signal when the display panel 1 performs a shutdown operation. The first voltage gating circuit 101 outputs a first power supply voltage VDD in response to the first control signal, and outputs a second power supply voltage VSS in response to the second control signal. The second voltage gating circuit 102 outputs a second power supply voltage VSS in response to the first control signal, and outputs a first power supply voltage VDD in response to the second control signal.

[0067] Specifically, the control unit 103 includes a comparator U1, which is electrically connected to the power module 30, and the comparator U1 is used to receive the data power supply voltage Vsd, and compare the data power supply voltage Vsd with a preset reference voltage Vref, and when the data power supply voltage Vsd is higher than the preset reference voltage Vref, determine that the display panel 1 is in a working state and output the first control signal, and when the data power supply voltage Vsd is lower than the preset reference voltage Vref, determine that the display panel 1 is performing a shutdown operation and output the second control signal. In the embodiment of the present application, the positive input terminal of the comparator U1 is used to receive the preset reference voltage Vref, and the negative input terminal of the comparator U1 is used to receive the data power supply voltage Vsd. Of course, in other embodiments, the control unit 103 can also be other circuits capable of realizing a comparison function, for example, a microprocessor MCU, a comparison circuit composed of transistors, etc. Wherein, when the display panel 1 is in a working state, the data power supply voltage Vsd is higher than the preset reference voltage Vref. When the display panel 1 performs a shutdown operation, the voltage value of the data power voltage Vsd will decrease, thereby being lower than the preset reference voltage Vref.

[0068] The first voltage gating circuit 101 includes a first switch tube T1 and a second switch tube T2, wherein the first switch tube T1 is electrically connected between the first voltage input terminal VDD and the first voltage output terminal 1011. The second switch tube T2 is electrically connected between the second voltage input terminal VSS and the first voltage output terminal 1011.

[0069] The second voltage gating circuit 102 includes a third switch tube T3 and a fourth switch tube T4, wherein the third switch tube T3 is electrically connected between the first voltage input terminal VDD and the second voltage output terminal 1021. The fourth switch tube T4 is electrically connected between the second voltage input terminal VSS and the second voltage output terminal 1021. The switch tubes T1 to T4 may be at least one of a triode or a MOS tube, and the switch tubes T1 to T4 may be amorphous silicon thin film transistors (a-SiTFT), or low temperature polycrystalline silicon thin film transistors (LTPS TFT), or oxide semiconductor thin film transistors (Oxide TFT). The active layer of the oxide semiconductor thin film transistor is oxide semiconductor (Oxide), such as Indium Gallium Zinc Oxide (IGZO). Of course, in other embodiments, the first voltage gating circuit 101 and the second voltage gating circuit 102 may also use other types of gating elements, for example, an electromagnetic relay with two pairs of contacts.

[0070] The control ends of the first switch tube T1 and the fourth switch tube T4 are both electrically connected to the output end of the comparator U1, and are both turned on in response to the first control signal, and are both turned off in response to the second control signal. The second switch tube T2 and the third switch tube T3 are both electrically connected to the output end of the comparator U1, and are both turned on in response to the second control signal, and are both turned off in response to the first control signal. In the embodiment of the present application, the first control signal is a low-level signal, the second control signal is a high-level signal, the first switch tube T1 and the fourth switch tube T4 are low-level turned-on switch tubes, and the second switch tube T2 and the third switch tube T3 are high-level turned-on switch tubes.

[0071] It should be noted that the power supply module 30 is used to output the data power supply voltage Vsd, the first power supply voltage VDD, and the second power supply voltage VSS when the display panel 1 is in a working state, and to stop outputting the data power supply voltage Vsd, the first power supply voltage VDD, and the second power supply voltage VSS when the display panel 1 performs a shutdown operation. Therefore, when the display panel 1 performs a shutdown operation, the voltage value of the data power supply voltage Vsd will drop, thereby being lower than the preset reference voltage Vref. In addition, since the power supply line for transmitting the power supply voltage (including the first power supply voltage VDD and the second power supply voltage VSS) in the display panel 1 is relatively long, there is an equivalent capacitance between the power supply lines and between the power supply lines and the ground terminal. Therefore, when the display panel 1 performs a shutdown operation, the first power supply voltage VDD and the second power supply voltage VSS received by each pixel unit 100 will slowly decrease due to the equivalent capacitance on the line, and will not drop to zero immediately. Therefore, even if the power module 30 stops outputting the first power supply voltage VDD and the second power supply voltage VSS when the display panel 1 performs a shutdown operation, the residual voltage on the power supply line can provide a reverse bias voltage for each pixel unit 100, thereby achieving the purpose of weakening or eliminating the built-in electric field of the light-emitting element OLED of the pixel unit 100.

[0072] Optionally, the preset reference voltage Vref may also be provided by the power module 30. To ensure that the voltage value of the preset reference voltage Vref is higher than the received data power voltage Vsd when the display panel 1 performs a shutdown operation, the control unit 103 further includes a storage capacitor C1 electrically connected between the non-inverting input terminal of the comparator U1 and the ground terminal. The storage capacitor C1 is used to store electrical energy when the display panel 1 is in a working state, and continues to output the preset reference voltage Vref to the non-inverting input terminal of the comparator U1 when the display panel 1 performs a shutdown operation. In this way, the reliability of the power supply voltage control circuit 10 can be improved.

[0073] The power supply voltage control circuit 10 provided in the present application controls the first voltage gating circuit 101 to output the second power supply voltage VSS and controls the second voltage gating circuit 102 to output the first power supply voltage VDD through the control unit 103 when the display panel 1 performs a shutdown operation, thereby providing a reverse bias voltage for the pixel unit 100, so that the uncombined excess holes or electrons in the light-emitting unit of each light-emitting element OLED change the direction of movement and move in the opposite direction, thereby relatively consuming the uncombined electrons and holes accumulated on the interface inside the light-emitting layer, thereby weakening or eliminating the built-in electric field formed by the excess carriers in the working state inside the light-emitting element OLED, thereby improving the stability of the light-emitting brightness, improving the energy utilization efficiency, and extending the service life of the display panel 1.

[0074] Based on the same inventive concept, please refer to Figure 4 The embodiment of the present application further provides a pixel circuit 100 ′, and the pixel circuit 100 ′ is applied to a display panel. Specifically, the pixel circuit 100 ′ includes a pixel unit 100 and the above-mentioned power supply voltage control circuit 10 .

[0075] The pixel unit 100 includes a driving voltage input terminal 201 , a reference voltage input terminal 202 and a light emitting element. The anode of the light emitting element OLED is electrically connected to the driving voltage input terminal 201 , and the cathode of the light emitting element OLED is electrically connected to the reference voltage input terminal 202 .

[0076] The power supply voltage control circuit 10 is electrically connected to the driving voltage input terminal 201 and the reference voltage input terminal 202, respectively. The power supply voltage control circuit 10 is used to output a first power supply voltage VDD to the driving voltage input terminal 201 and a second power supply voltage VSS to the reference voltage input terminal 202 when the display panel is in the working state, thereby providing a forward bias voltage for the pixel unit 100, so that the light-emitting element OLED can emit light based on the forward bias voltage. The power supply voltage control circuit 10 is also used to output the second power supply voltage VSS to the driving voltage input terminal 201 and the first power supply voltage VDD to the reference voltage input terminal 202 when the display panel performs a shutdown operation, thereby providing a reverse bias voltage for the pixel unit 100 to weaken or eliminate the built-in electric field of the light-emitting element OLED.

[0077] Based on the same inventive concept, the embodiment of the present application also provides another display panel, which includes a plurality of the above-mentioned pixel circuits 100' arranged in an array. It should be noted that the display panel in this embodiment is different from Figure 1 The difference of the display panel 1 shown is that: in the display panel of this embodiment, each pixel unit 100 is correspondingly configured with a power supply voltage control circuit 10, and together they constitute a pixel circuit 100'. Figure 1 In the display panel 1 shown, only one power supply voltage control circuit 10 is configured, that is, each pixel unit 100 shares one power supply voltage control circuit 10, so that the structure of the display panel can be simplified and the cost can be saved.

[0078] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A power supply voltage control circuit, used to provide a first power supply voltage and a second power supply voltage for a pixel unit in a display panel; wherein: The pixel unit comprises a driving voltage input terminal, a reference voltage input terminal and a light emitting element, wherein an anode of the light emitting element is electrically connected to the driving voltage input terminal, a cathode of the light emitting element is electrically connected to the reference voltage input terminal, and the first power supply voltage is higher than the second power supply voltage; wherein the power supply voltage control circuit comprises: A first voltage gating circuit, used for receiving and selecting to output one of the first power supply voltage and the second power supply voltage to a driving voltage input terminal of the pixel unit; a second voltage gating circuit, configured to receive and select one of the first power supply voltage and the second power supply voltage to output to a reference voltage input terminal of the pixel unit; and a control unit, electrically connected to the first voltage gating circuit and the second voltage gating circuit respectively; the control unit is used to control the first voltage gating circuit to output the first power supply voltage and the second voltage gating circuit to output the second power supply voltage when the display panel is in an operating state, thereby providing a forward bias voltage for the pixel unit, so that the light-emitting element of the pixel unit can emit light based on the forward bias voltage; the control unit is also used to control the first voltage gating circuit to output the second power supply voltage and the second voltage gating circuit to output the first power supply voltage when the display panel performs a shutdown operation, thereby providing a reverse bias voltage for the pixel unit, so as to weaken or eliminate the built-in electric field of the light-emitting element of the pixel unit; The control unit is used to detect whether the display panel is in an operating state, and output a first control signal when the display panel is in an operating state, and to detect whether the display panel is performing a shutdown operation, and output a second control signal when the display panel is performing a shutdown operation; The first voltage gating circuit outputs a first power supply voltage in response to the first control signal, and outputs a second power supply voltage in response to the second control signal; The second voltage gating circuit outputs a second power supply voltage in response to the first control signal, and outputs a first power supply voltage in response to the second control signal.

2. The power supply voltage control circuit according to claim 1, characterized in that: The display panel further comprises a power supply module, wherein the power supply module is used to output a data power supply voltage when the display panel is in an operating state, and to stop outputting the data power supply voltage when the display panel performs a shutdown operation; The control unit includes a comparator, which is electrically connected to the power module. The comparator is used to receive the data power supply voltage and compare the data power supply voltage with a preset reference voltage, and determine that the display panel is in a working state and output the first control signal when the data power supply voltage is higher than the preset reference voltage, and determine that the display panel is performing a shutdown operation and output the second control signal when the data power supply voltage is lower than the preset reference voltage.

3. The power supply voltage control circuit according to claim 1, characterized in that: The power supply voltage control circuit also includes: A first voltage input terminal, used for receiving the first power supply voltage; A second voltage input terminal, used for receiving the second power supply voltage; A first voltage output terminal electrically connected to a driving voltage input terminal of the pixel unit; and A second voltage output terminal, electrically connected to a reference voltage input terminal of the pixel unit; The first voltage gating circuit comprises: A first switch tube, electrically connected between the first voltage input terminal and the first voltage output terminal; A second switch tube, electrically connected between the second voltage input terminal and the first voltage output terminal; The second voltage gating circuit comprises: A third switch tube is electrically connected between the first voltage input terminal and the second voltage output terminal; and a fourth switch tube, electrically connected between the second voltage input terminal and the second voltage output terminal; The control ends of the first switch tube and the fourth switch tube are both electrically connected to the control unit, and are both turned on in response to the first control signal; the second switch tube and the third switch tube are both electrically connected to the control unit, and are both turned on in response to the second control signal.

4. The power supply voltage control circuit according to claim 2, characterized in that: The non-inverting input terminal of the comparator is used to receive the preset reference voltage, and the inverting input terminal of the comparator is used to receive the data power supply voltage.

5. The power supply voltage control circuit according to claim 4, characterized in that: The control unit also includes a storage capacitor electrically connected between the non-inverting input terminal of the comparator and the ground terminal, and the storage capacitor is used to continue to output the preset reference voltage to the non-inverting input terminal of the comparator when the display panel performs a shutdown operation.

6. The power supply voltage control circuit according to claim 3, characterized in that: The first control signal is a low-level signal, the second control signal is a high-level signal, the first switch tube and the fourth switch tube are switch tubes that are turned on at a low level, and the second switch tube and the third switch tube are switch tubes that are turned on at a high level.

7. A pixel circuit, applied to a display panel, characterized in that: The pixel circuit comprises: A pixel unit, comprising a driving voltage input terminal, a reference voltage input terminal and a light emitting element, wherein an anode of the light emitting element is electrically connected to the driving voltage input terminal, and a cathode of the light emitting element is electrically connected to the reference voltage input terminal; and The power supply voltage control circuit as described in any one of claims 1 to 6, wherein the power supply voltage control circuit is electrically connected to a driving voltage input terminal and a reference voltage input terminal respectively, and the power supply voltage control circuit is used to output a first power supply voltage to the driving voltage input terminal and a second power supply voltage to the reference voltage input terminal when the display panel is in a working state; the power supply voltage control circuit is also used to output the second power supply voltage to the driving voltage input terminal and the first power supply voltage to the reference voltage input terminal when the display panel performs a shutdown operation.

8. A driving circuit for providing a first power supply voltage and a second power supply voltage to drive a pixel unit in a display panel, characterized in that: The driving circuit comprises: a power supply module, configured to generate the first power supply voltage and the second power supply voltage; and The power supply voltage control circuit according to any one of claims 1 to 6, wherein the power supply module is electrically connected to the power supply voltage control circuit, and the power supply voltage control circuit is used to output the first power supply voltage and the second power supply voltage to the pixel unit in the display panel.

9. A display panel, characterized in that: include: A plurality of pixel units arranged in an array; as well as The driving circuit as described in claim 8, wherein the driving circuit is electrically connected to the plurality of pixel units respectively, and the driving circuit is used to drive the corresponding pixel units to emit light when the display panel is in an operating state, and to weaken or eliminate the built-in electric field of the light-emitting elements of each pixel unit when the display panel performs a shutdown operation.

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