CN115662350A - Power supply voltage control circuit, pixel circuit, drive circuit and display panel - Google Patents
Power supply voltage control circuit, pixel circuit, drive circuit and display panel Download PDFInfo
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- CN115662350A CN115662350A CN202211343001.7A CN202211343001A CN115662350A CN 115662350 A CN115662350 A CN 115662350A CN 202211343001 A CN202211343001 A CN 202211343001A CN 115662350 A CN115662350 A CN 115662350A
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Abstract
The application provides a power supply voltage control circuit, a pixel circuit, a driving circuit and a display panel. The first voltage gating circuit is used for selectively outputting one of the first power supply voltage and the second power supply voltage to the driving voltage input end of the pixel unit. The second voltage gating circuit is used for selectively outputting one of the first power supply voltage and the second power supply voltage to the reference voltage input end of the pixel unit. The control unit is used for controlling the first voltage gating circuit to output the second power voltage and controlling the second voltage gating circuit to output the first power voltage when the display panel executes shutdown operation, and provides reverse bias voltage for the pixel unit to weaken or eliminate a built-in electric field of the light-emitting element of the pixel unit. The power supply voltage control circuit provided by the application can weaken or eliminate the built-in electric field of the light-emitting element and prolong the service life of the display panel.
Description
Technical Field
The application relates to the technical field of display panels, in particular to a power supply voltage control circuit, a pixel circuit, a driving circuit and a display panel.
Background
An OLED (Organic Light-Emitting Diode) is also called an Organic electroluminescent display or an Organic Light-Emitting semiconductor. The OLED is a current-type organic light emitting device, and emits light by injection and recombination of carriers, and the intensity of light emission is proportional to the injected current. The OLED display panel has the advantages of no blue light hazard, soft light, flexibility, foldability, no stroboflash, high color rendering quality and the like, and has gradually become one of mainstream display panels in the market.
The light emitting elements in the existing OLED display panel are mostly driven by direct current, and have the defect of easy aging. Specifically, the reason why the light emitting element in the direct current driving type OLED display panel is aged is as follows: the transport direction of holes and electrons in the light-emitting element is fixed, and they are injected into the light-emitting layer from the positive and negative electrodes, respectively, to form excitons in the light-emitting layer, which emit light by radiation. In which excess holes (or electrons) not involved in recombination are partly accumulated at the hole transport layer/light-emitting layer (or light-emitting layer/electron transport layer) interface, and partly flow into the electrode over the potential barrier. With the increase of the usage time, many non-recombined carriers accumulated at the internal interface of the light emitting layer form a built-in electric field inside the light emitting element, so that the threshold voltage of the light emitting element is increased continuously, the light emitting brightness of the light emitting element is reduced continuously, and the energy utilization efficiency is reduced gradually.
Disclosure of Invention
In view of the above, the present invention provides a power supply voltage control circuit, a pixel circuit, a driving circuit and a display panel, and aims to solve the problem that a light emitting element in a conventional dc-driven OLED display panel is prone to aging.
The application provides a power supply voltage control circuit, power supply voltage control circuit is used for providing first power supply voltage and second power supply voltage for the pixel unit in display panel. The pixel unit comprises a driving voltage input end, a reference voltage input end and a light-emitting element, wherein the anode of the light-emitting element is electrically connected with the driving voltage input end, the cathode of the light-emitting element is electrically connected with the reference voltage input end, and the first power supply voltage is higher than the second power supply voltage. The power supply voltage control circuit includes a first voltage gate circuit, a second voltage gate circuit, and a control unit. The first voltage gating circuit is used for receiving and selectively outputting one of the first power supply voltage and the second power supply voltage to a driving voltage input end of the pixel unit. The second voltage gating circuit is used for receiving and selectively outputting one of the first power supply voltage and the second power supply voltage to a reference voltage input end of the pixel unit. The control unit is electrically connected with the first voltage gating circuit and the second voltage gating circuit respectively. The control unit is used for controlling the first voltage gating circuit to output the first power supply voltage and controlling the second voltage gating circuit to output the second power supply voltage when the display panel is in a working state, so that a forward bias voltage is provided for the pixel unit, and the light-emitting element of the pixel unit can emit light based on the forward bias voltage. The control unit is further configured to control the first voltage gating circuit to output the second power voltage and control the second voltage gating circuit to output the first power voltage when the display panel performs a shutdown operation, so as to provide a reverse bias voltage for the pixel unit, thereby weakening or eliminating a built-in electric field of a light emitting element of the pixel unit.
The application provides a power supply voltage control circuit, when the display panel carries out shutdown operation through the control unit, control first voltage gate circuit and export second supply voltage, and control second voltage gate circuit and export first supply voltage, thereby for the pixel unit provides reverse bias voltage, make in each light-emitting component surplus hole or electron that do not compound in the light-emitting unit change the direction of motion, move towards opposite direction, thereby consumed the electron and the hole that do not compound that luminescent layer internal interface accumulated relatively, thereby can weaken or eliminate the surplus carrier under operating condition and be in the inside built-in electric field that forms of light-emitting component, and then can improve the stability of luminance, the utilization efficiency of improvement energy, extension display panel's life.
Optionally, the control unit is configured to detect whether the display panel is in a working state, output a first control signal when the display panel is in the working state, detect whether the display panel is performing a shutdown operation, and output a second control signal when the display panel is performing the shutdown operation. The first voltage gating circuit outputs a first supply voltage in response to the first control signal and a second supply voltage in response to the second control signal. The second voltage gating circuit outputs a second supply voltage in response to the first control signal and outputs a first supply voltage in response to the second control signal.
Optionally, the display panel further includes a power supply module, where the power supply module is configured to output a data power supply voltage when the display panel is in a working state, and stop outputting the data power supply voltage when the display panel executes a shutdown operation. The control unit comprises a comparator, the comparator is electrically connected with the power supply module, the comparator is used for receiving the data power supply voltage, comparing the data power supply voltage with a preset reference voltage, determining that the display panel is in a working state and outputs the first control signal when the data power supply voltage is higher than the preset reference voltage, and determining that the display panel executes shutdown operation and outputs the second control signal when the data power supply voltage is lower than the preset reference voltage.
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 for receiving the first power supply voltage. The second voltage input terminal is used for receiving the second power supply voltage. The first voltage output end is electrically connected with the driving voltage input end of the pixel unit. The second voltage output end is electrically connected with the reference voltage input end of the pixel unit. The first voltage gating circuit comprises a first switching tube and a second switching tube. The first switch tube is electrically connected between a first voltage input end and the first voltage output end. The second switch tube is electrically connected between a second voltage input end and the first voltage output end. The second voltage gating circuit comprises a third switching tube and a fourth switching tube. The third switching tube is electrically connected between the first voltage input end and the second voltage output end. The fourth switch tube is electrically connected between a second voltage input end and the second voltage output end. The control ends of the first switch tube and the fourth switch tube are electrically connected with the control unit and are conducted in response to the first control signal. The second switching tube and the third switching tube are both electrically connected with the control unit and are both turned on in response to the second control signal.
Optionally, a non-inverting input of the comparator is configured to receive the preset reference voltage, and an inverting input of the comparator is configured to receive the data power supply voltage.
Optionally, the control unit further includes a storage capacitor electrically connected between the positive input terminal of the comparator and a ground terminal, and the storage capacitor is configured to continue to output the preset reference voltage to the positive input terminal of the comparator when the display panel performs a shutdown operation.
Optionally, the first control signal is a low-level signal, the second control signal is a high-level signal, the first switching tube and the fourth switching tube are switching tubes that are switched on at a low level, and the second switching tube and the third switching tube are switching tubes that are switched on at a high level.
The embodiment of the application also provides a pixel circuit, which is applied to a display panel and comprises a pixel unit and the power supply voltage control circuit. The pixel unit comprises a driving voltage input end, a reference voltage input end and a light-emitting element, wherein the anode of the light-emitting element is electrically connected with the driving voltage input end, and the cathode of the light-emitting element is electrically connected with the reference voltage input end. The power supply voltage control circuit is electrically connected with the driving voltage input end and the reference voltage input end respectively, and is used for outputting a first power supply voltage to the driving voltage input end and outputting a second power supply voltage to the reference voltage input end when the display panel is in a working state. The power supply voltage control circuit is further configured to output a second power supply voltage to the driving voltage input terminal and output a first power supply voltage to the reference voltage input terminal when the display panel performs a shutdown operation.
The embodiment of the application further provides a driving circuit, wherein the driving circuit is used for providing a first power voltage and a second power voltage to drive a pixel unit in a display panel, and the driving circuit comprises a power module and the power voltage control circuit. Wherein the power module is configured to generate the first power voltage and the second power voltage. The power supply module is electrically connected with the power supply voltage control circuit, and the power supply voltage control circuit is used for outputting the first power supply voltage and the second power supply voltage to the pixel units in the display panel.
The embodiment of the application further provides a display panel, the display panel includes a plurality of pixel units arranged in an array and the above-mentioned drive circuit, the drive circuit is electrically connected with the plurality of pixel units respectively, the drive circuit is used for driving the corresponding pixel units to emit light when the display panel is in a working state, and the built-in electric field of the light-emitting element of each pixel unit is weakened or eliminated when the display panel executes shutdown operation.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
Fig. 1 is a schematic structural diagram of a display panel provided in an embodiment of the present application.
Fig. 2 is a schematic structural diagram of a pixel unit according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of a power supply voltage control circuit according to an embodiment of the present application.
Fig. 4 is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure.
Description of the main element symbols:
power supply voltage control circuit 10
Pixel circuit 100'
Scanning signal generating circuit 110
Data signal generating circuit 120
First switch tube T1
Second switch tube T2
Third switch tube T3
Fourth switch tube T4
First voltage input terminal VDD
Second voltage input terminal VSS
A first voltage output terminal 1011
Second voltage output end 1021
Drive transistor M
Scanning transistor T0
Light-emitting element OLED
First voltage gating circuit 101
Second voltage gating circuit 102
Comparator U1
Storage capacitors C1, cst
Drive voltage input terminal 201
The following detailed description will further illustrate the present application in conjunction with the above-described figures.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present disclosure.
In the description of the present application, it is noted that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The light emitting element OLED generally includes an anode, a light emitting unit, and a cathode formed on a substrate base plate. 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 the holes meet and are combined in the light-emitting layer to form excitons, and the excitons transfer energy to light-emitting molecules in the electroluminescent layer under the action of an electric field, so that the light-emitting molecules emit visible light.
However, the light emitting elements in the conventional OLED display panel are often driven by direct current, and thus have a disadvantage of being susceptible to aging. Specifically, the reason why the light emitting element in the direct current driving type OLED display panel is aged is as follows: the transport direction of holes and electrons in the light-emitting element is fixed, and they are injected into the light-emitting layer from the positive and negative electrodes, respectively, to form excitons in the light-emitting layer, which emit light by radiation. In which excess holes (or electrons) not involved in recombination are partly accumulated at the hole transport layer/light-emitting layer (or light-emitting layer/electron transport layer) interface, and partly flow into the electrode over the potential barrier. With the increase of the usage time, many non-recombined carriers accumulated at the internal interface of the light emitting layer form a built-in electric field inside the light emitting element, so that the threshold voltage of the light emitting element is increased continuously, the light emitting brightness of the light emitting element is reduced continuously, and the energy utilization efficiency is reduced gradually.
Referring to fig. 1, in order to solve the problem that the light emitting elements in the conventional dc driving type OLED display panel are prone to aging, an embodiment of the present invention provides a display panel 1, where the display panel 1 includes a plurality of pixel units 100 and a driving circuit 200. The pixel units 100 are arranged in an array in a display area of the substrate of the display panel 1. The driving circuit 200 is electrically connected to the plurality of pixel units 100, and the driving circuit 200 is configured to drive the corresponding pixel units 100 to emit light when the display panel 1 is in an operating state (that is, the display panel 1 is in a power-on and power-on state, and is used for displaying a picture), and weaken or eliminate a built-in electric field in a light emitting element of each pixel unit 100 when the display panel 1 performs a power-off operation (that is, the display panel 1 is powered off and power-off), so as to solve a problem that the light emitting element in the dc-driven OLED display panel is prone to aging.
Specifically, the driving circuit 200 includes a scan signal generating circuit 110, a data signal generating circuit 120, a power supply voltage control circuit 10, and a power supply module 30. The scan signal generating circuit 110 is electrically connected to the pixel units 100 in each row through a plurality of scan lines 111, and the scan signal generating circuit 110 is configured to generate a plurality of scan signals for each row of the pixel units 100. 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 configured 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 column of pixel driving circuits. The power supply module 30 is configured to provide a power supply voltage for each circuit module in the display panel 1, for example, provide 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, provide the data power supply voltage Vsd for the data signal generating circuit 120, and enable the data signal generating circuit 120 to generate the data voltage Vdata based on the data power supply voltage Vsd. The power voltage control circuit 10 is electrically connected to the driving voltage input terminal 201 of each pixel unit 100 through a first voltage output terminal 1011 thereof, and is electrically connected to the reference voltage input terminal 202 of each pixel unit 100 through a second voltage output terminal 1021 thereof, and the power voltage control circuit 10 is configured to provide a first power voltage VDD and a second power voltage VSS for the pixel units 100 in the display panel 1. Specifically, when the display panel 1 is in the operating state, the power voltage control circuit 10 outputs the first power 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 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 a shutdown operation, the power voltage control circuit 10 outputs the second power voltage VSS to the driving voltage input terminal 201 of each of the pixel units 100 through the first voltage output terminal 1011, and outputs the first power voltage VDD to the reference voltage input terminal 202 of each of the pixel units 100 through the second voltage output terminal 1021.
Referring to fig. 2, fig. 2 shows a pixel unit 100 with a 2T1C structure in the prior art, but in other embodiments, the pixel unit 100 may also adopt other types of circuit structures, such as 5T1C, 6T1C, 7T1C, and the like. The pixel unit 100 includes the driving voltage input terminal 201, the reference voltage input terminal 202, a scan transistor T0, a driving transistor M, an energy storage capacitor Cst, and a light emitting element OLED.
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 voltage VDD is higher than the second power voltage VSS. The pixel unit 100 can drive the light emitting element OLED to emit light.
When the display panel 1 is in an operating state, the cathode of the light emitting element OLED receives the second power voltage VSS through the reference voltage input terminal 202, and the second connection terminal of the driving transistor M receives the first power voltage VDD through the driving voltage input terminal 201, that is, the pixel unit 100 receives a forward bias voltage. The first connection end 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 end of the SCAN transistor T0, the first connection end of the SCAN transistor T0 is electrically connected to the data line 121 to receive the data voltage Vdata, and the gate of the SCAN transistor T0 is electrically connected to the SCAN line 111 to receive the SCAN signal SCAN. A first end of the storage capacitor Cst is electrically connected to the gate of the driving transistor M, and a second end of the storage capacitor Cst is electrically connected to the cathode of the light emitting element OLED. Illustratively, when the scanning signal is an on signal, the scanning transistor T0 is turned on, the data voltage Vdata on the data line 121 charges the energy storage capacitor Cst through the scanning transistor T0 to adjust the voltage at the first end of the energy storage capacitor Cst to the data voltage Vdata, the driving transistor M drives the light emitting element OLED to emit light based on the data voltage Vdata received by the gate thereof and the first power voltage VDD received by the first connection end thereof, at this time, the light emitting element OLED enters a forward bias state, the hole transport layer in the light emitting unit of the light emitting element OLED transports holes to the light emitting layer, the electron transport layer in the light emitting unit of the light emitting element OLED transports electrons to the light emitting layer, and the electrons and the holes meet and recombine at the light emitting layer of the light emitting unit to make the light emitting molecules emit visible light.
When the display panel 1 performs a shutdown operation, the cathode of the light emitting element OLED receives the first power voltage VDD through the reference voltage input terminal 202, and the second connection terminal of the driving transistor M receives the second power 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 by the energy storage capacitor Cst, so that the light emitting element OLED enters a reverse bias state, and at this time, the light emitting element OLED enters a reverse bias state, so that the non-recombined excess holes or electrons in the light emitting unit of the light emitting element OLED change the 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, so that the non-recombined electrons and holes accumulated on the internal interface of the light emitting layer are relatively consumed, and thus the built-in electric field formed by the excess carriers in the light emitting element OLED in the working state can be weakened or eliminated, the stability of the light emitting brightness can be improved, the utilization efficiency of energy can be improved, and the service life of the display panel 1 can be prolonged.
The circuit structure and operation principle of the power voltage control circuit 10 will be described in detail with reference to fig. 3, and the power 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.
The first voltage input terminal VDD is electrically connected to the power supply module 30, and the first voltage input terminal VDD is configured 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 for receiving the second power 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 end 1021 is electrically connected to the reference voltage input end 202 of each pixel unit 100.
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 configured to receive and selectively output one of the first power voltage VDD and the second power voltage VSS to the driving voltage input terminal 201 of each pixel unit 100.
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 configured to receive and selectively output one of the first power voltage VDD and the second power voltage VSS to the reference voltage input terminal 202 of each of the pixel units 100.
The control unit 103 is electrically connected to the first voltage gate circuit 101 and the second voltage gate circuit 102, respectively. The control unit 103 is configured to control the first voltage gate circuit 101 to output the first power voltage VDD and control the second voltage gate circuit 102 to output the second power voltage VSS when the display panel 1 is in an operating state, so as to provide a forward bias voltage for the pixel unit 100, and enable the light emitting element OLED of the pixel unit 100 to emit light based on the forward bias voltage. The control unit 103 is further configured to control the first voltage gating circuit 101 to output the second power voltage VSS and control the second voltage gating circuit 102 to output the first power 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 a built-in electric field of the light emitting element OLED of the pixel unit 100.
Further, the control unit 103 is configured 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 the 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 is performing the shutdown operation. The first voltage gate circuit 101 outputs a first power voltage VDD in response to the first control signal and outputs a second power voltage VSS in response to the second control signal. The second voltage gate circuit 102 outputs the second power supply voltage VSS in response to the first control signal and outputs the first power supply voltage VDD in response to the second control signal.
Specifically, the control unit 103 includes a comparator U1, the comparator U1 is electrically connected to the power module 30, and the comparator U1 is configured to receive the data power voltage Vsd, compare the data power voltage Vsd with a preset reference voltage Vref, determine that the display panel 1 is in an operating state and output the first control signal when the data power voltage Vsd is higher than the preset reference voltage Vref, and determine that the display panel 1 is performing a shutdown operation and output the second control signal when the data power voltage Vsd is lower than the preset reference voltage Vref. In the embodiment of the present application, a non-inverting input terminal of the comparator U1 is configured to receive the preset reference voltage Vref, and an inverting input terminal of the comparator U1 is configured to receive the data power voltage Vsd. Of course, in other embodiments, the control unit 103 may also be other circuits capable of implementing the comparison function, for example, a microprocessor MCU, a comparison circuit composed of transistors, and the like. When the display panel 1 is in an operating state, the data power 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 is decreased to be lower than the preset reference voltage Vref.
The first voltage gating circuit 101 includes a first switch transistor T1 and a second switch transistor T2, wherein the first switch transistor T1 is electrically connected between a first voltage input terminal VDD and the first voltage output terminal 1011. The second switch tube T2 is electrically connected between a second voltage input terminal VSS and the first voltage output terminal 1011.
The second voltage gating circuit 102 includes a third switch transistor T3 and a fourth switch transistor T4, wherein the third switch transistor T3 is electrically connected between the first voltage input terminal VDD and the second voltage output terminal 1021. The fourth switch transistor T4 is electrically connected between the second voltage input terminal VSS and the second voltage output terminal 1021. The switching tubes T1-T4 can adopt at least one of a triode or an MOS tube, and the switching tubes T1-T4 can adopt amorphous silicon thin film transistors (a-Si TFT), or low-temperature polycrystalline silicon thin film transistors (LTPS TFT), or Oxide semiconductor thin film transistors (Oxide TFT). An Oxide semiconductor (Oxide), such as Indium Gallium Zinc Oxide (IGZO), is used as an active layer of the Oxide semiconductor thin film transistor. Of course, in other embodiments, the first voltage gating circuit 101 and the second voltage gating circuit 102 may also adopt other types of gating elements, for example, an electromagnetic relay having two pairs of contacts.
The control terminals of the first switch tube T1 and the fourth switch tube T4 are both electrically connected with the output terminal of the comparator U1, 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 switching tube T2 and the third switching tube T3 are both electrically connected to an output terminal of the comparator U1, are both turned on in response to the second control signal, and are both turned off in response to the first control signal. In this embodiment, 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 switch tubes turned on at a low level, and the second switch tube T2 and the third switch tube T3 are switch tubes turned on at a high level.
It should be noted that the power module 30 is configured to output the data power voltage Vsd, the first power voltage VDD and the second power voltage VSS when the display panel 1 is in the operating state, and stop outputting the data power voltage Vsd, the first power voltage VDD and the second power voltage VSS when the display panel 1 performs a shutdown operation, so that when the display panel 1 performs the shutdown operation, the voltage value of the data power voltage Vsd will decrease and be lower than the preset reference voltage Vref. In addition, since the power lines for transmitting the power voltages (including the first power voltage VDD and the second power voltage VSS) in the display panel 1 are long, and therefore equivalent capacitances exist between the power lines and a ground terminal, when the display panel 1 performs a shutdown operation, the first power voltage VDD and the second power voltage VSS received by each pixel unit 100 may slowly decrease due to the equivalent capacitance on the lines without immediately decreasing to zero, and therefore, even if the power module 30 stops outputting the first power voltage VDD and the second power voltage VSS when the display panel 1 performs the shutdown operation, the voltage remaining on the power lines may provide an inverted bias voltage for each pixel unit 100, so as to achieve the purpose of reducing or eliminating the built-in electric field of the light emitting element OLED of the pixel unit 100.
Optionally, the preset reference voltage Vref may also be provided by the power module 30, and in order 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 a positive input terminal and a ground terminal of the comparator U1, where the storage capacitor C1 is configured to store electric energy when the display panel 1 is in an operating state, and continue to output the preset reference voltage Vref to the positive input terminal of the comparator U1 when the display panel 1 performs the shutdown operation. In this way, the reliability of the power supply voltage control circuit 10 can be improved.
The power supply voltage control circuit 10 provided by the present application, when the display panel 1 performs a shutdown operation through the control unit 103, controls the first voltage gate circuit 101 to output the second power supply voltage VSS, and controls the second voltage gate circuit 102 to output the first power supply voltage VDD, so as to provide a reverse bias voltage for the pixel unit 100, so that the non-recombined excess holes or electrons in the light emitting units in the light emitting elements OLED change the moving direction and move toward the opposite direction, thereby relatively consuming the non-recombined electrons and holes accumulated on the internal interface of the light emitting layer, and thus weakening or eliminating the built-in electric field formed inside the light emitting elements OLED by the excess carriers in the operating state, further improving the stability of the light emitting elements OLED, improving the utilization efficiency of the energy, and prolonging the service life of the display panel 1.
Based on the same inventive concept, referring to fig. 4, an embodiment of the present application further provides a pixel circuit 100', where the pixel circuit 100' is applied in a display panel, and specifically, the pixel circuit 100' includes a pixel unit 100 and the power supply voltage control circuit 10.
The pixel unit 100 includes a driving voltage input terminal 201, a reference voltage input terminal 202, and a light emitting element, an anode of the light emitting element OLED is electrically connected to the driving voltage input terminal 201, and a cathode of the light emitting element OLED is electrically connected to the reference voltage input terminal 202.
The power voltage control circuit 10 is electrically connected to the driving voltage input terminal 201 and the reference voltage input terminal 202, respectively, and the power voltage control circuit 10 is configured to output a first power voltage VDD to the driving voltage input terminal 201 and a second power voltage VSS to the reference voltage input terminal 202 when the display panel is in an operating state, so as to provide a forward bias voltage for the pixel unit 100, and enable the light emitting element OLED to emit light based on the forward bias voltage. The power voltage control circuit 10 is further configured to output a second power voltage VSS to the driving voltage input terminal 201 and output a first power voltage VDD to the reference voltage input terminal 202 when the display panel performs a shutdown operation, so as to provide a reverse bias voltage for the pixel unit 100, so as to weaken or eliminate a built-in electric field of the light emitting element OLED.
Based on the same inventive concept, the present application provides another display panel, which includes a plurality of pixel circuits 100' arranged in an array. Note that the display panel in this embodiment is different from the display panel 1 shown in fig. 1 in that: in the display panel of the present embodiment, each pixel unit 100 is provided with one of the power supply voltage control circuits 10, and together form one pixel circuit 100'. However, in the display panel 1 shown in fig. 1, only one power voltage control circuit 10 is configured, that is, each pixel unit 100 shares one power voltage control circuit 10, so that the structure of the display panel can be simplified and the cost can be saved.
While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A power supply voltage control circuit is used for providing a first power supply voltage and a second power supply voltage for a pixel unit in a display panel; the pixel unit comprises a driving voltage input end, a reference voltage input end and a light-emitting element, wherein the anode of the light-emitting element is electrically connected with the driving voltage input end, the cathode of the light-emitting element is electrically connected with the reference voltage input end, and the first power supply voltage is higher than the second power supply voltage; characterized in that the supply voltage control circuit comprises:
a first voltage gating circuit for receiving and selectively outputting 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 for receiving and selectively outputting one of the first power supply voltage and the second power supply voltage to a reference voltage input terminal of the pixel unit; and
the control unit is electrically connected with the first voltage gating circuit and the second voltage gating circuit respectively; the control unit is used for controlling the first voltage gating circuit to output the first power supply voltage and controlling the second voltage gating circuit to output the second power supply voltage when the display panel is in a working state, so that a forward bias voltage is provided for the pixel unit, and the light-emitting element of the pixel unit can emit light based on the forward bias voltage; the control unit is further configured to control the first voltage gating circuit to output the second power voltage and control the second voltage gating circuit to output the first power voltage when the display panel performs a shutdown operation, so as to provide a reverse bias voltage for the pixel unit, thereby weakening or eliminating a built-in electric field of a light emitting element of the pixel unit.
2. The power supply voltage control circuit of claim 1, wherein the control unit is configured to detect whether the display panel is in an operating state and output a first control signal when the display panel is in the operating state, and detect whether the display panel is performing a shutdown operation and output a second control signal when the display panel is performing the shutdown operation;
the first voltage gating circuit outputs a first supply voltage in response to the first control signal and a second supply voltage in response to the second control signal;
the second voltage gating circuit outputs a second supply voltage in response to the first control signal and outputs a first supply voltage in response to the second control signal.
3. The power supply voltage control circuit according to claim 2, wherein the display panel further comprises a power supply module for outputting a data power supply voltage when the display panel is in an operating state and stopping outputting the data power supply voltage when the display panel performs a shutdown operation;
the control unit comprises a comparator, the comparator is electrically connected with the power supply module, the comparator is used for receiving the data power supply voltage, comparing the data power supply voltage with a preset reference voltage, determining that the display panel is in a working state and outputs the first control signal when the data power supply voltage is higher than the preset reference voltage, and determining that the display panel executes shutdown operation and outputs the second control signal when the data power supply voltage is lower than the preset reference voltage.
4. The supply voltage control circuit of claim 2,
the power supply voltage control circuit further includes:
a first voltage input for receiving the first supply voltage;
a second voltage input for receiving the second supply voltage;
the first voltage output end is electrically connected with the driving voltage input end of the pixel unit; and
the second voltage output end is electrically connected with the reference voltage input end of the pixel unit;
the first voltage gating circuit includes:
the first switch tube is electrically connected between a first voltage input end and the first voltage output end;
the second switch tube is electrically connected between a second voltage input end and the first voltage output end;
the second voltage gating circuit includes:
the third switching tube is electrically connected between the first voltage input end and the second voltage output end; and
the fourth switching tube is electrically connected between the second voltage input end and the second voltage output end;
the control ends of the first switch tube and the fourth switch tube are electrically connected with the control unit and are conducted in response to the first control signal; the second switching tube and the third switching tube are both electrically connected with the control unit and are both turned on in response to the second control signal.
5. The power supply voltage control circuit of claim 3, wherein a non-inverting input of the comparator is configured to receive the predetermined reference voltage, and an inverting input of the comparator is configured to receive the data supply voltage.
6. The power supply voltage control circuit of claim 5, wherein the control unit further comprises a storage capacitor electrically connected between the positive input terminal and a ground terminal of the comparator, the storage capacitor being configured to continue outputting the predetermined reference voltage to the positive input terminal of the comparator when the display panel performs a power-off operation.
7. The power supply voltage control circuit of claim 4, wherein 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 low level conducting switch tubes, and the second switch tube and the third switch tube are high level conducting switch tubes.
8. A pixel circuit applied to a display panel, the pixel circuit comprising:
the pixel unit comprises a driving voltage input end, a reference voltage input end and a light-emitting element, wherein the anode of the light-emitting element is electrically connected with the driving voltage input end, and the cathode of the light-emitting element is electrically connected with the reference voltage input end; and
the power supply voltage control circuit according to any one of claims 1 to 7, the power supply voltage control circuit being electrically connected to a driving voltage input terminal and a reference voltage input terminal, respectively, the power supply voltage control circuit being configured 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 an operating state; the power supply voltage control circuit is further configured to output a second power supply voltage to the driving voltage input terminal and output a first power supply voltage to the reference voltage input terminal when the display panel performs a shutdown operation.
9. A driving circuit for providing a first power supply voltage and a second power supply voltage to drive a pixel cell in a display panel, the driving circuit comprising:
a power supply module for generating the first power supply voltage and the second power supply voltage; and
the power supply voltage control circuit of any one of claims 1-7, wherein the power supply module is electrically connected to the power supply voltage control circuit, the power supply voltage control circuit to output the first power supply voltage and the second power supply voltage to a pixel cell in the display panel.
10. A display panel, comprising:
a plurality of pixel units arranged in an array; and
the driving circuit according to claim 9, wherein the driving circuit is electrically connected to the plurality of pixel units, and the driving circuit is configured to drive the corresponding pixel units to emit light when the display panel is in an operating state, and to weaken or eliminate a built-in electric field of the light emitting elements of the pixel units when the display panel performs a shutdown operation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211343001.7A CN115662350A (en) | 2022-10-31 | 2022-10-31 | Power supply voltage control circuit, pixel circuit, drive circuit and display panel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211343001.7A CN115662350A (en) | 2022-10-31 | 2022-10-31 | Power supply voltage control circuit, pixel circuit, drive circuit and display panel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115662350A true CN115662350A (en) | 2023-01-31 |
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ID=84993450
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211343001.7A Pending CN115662350A (en) | 2022-10-31 | 2022-10-31 | Power supply voltage control circuit, pixel circuit, drive circuit and display panel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115662350A (en) |
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2022
- 2022-10-31 CN CN202211343001.7A patent/CN115662350A/en active Pending
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