CN111243492B - Pixel circuit, pixel driving method and display device - Google Patents
Pixel circuit, pixel driving method and display device Download PDFInfo
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- CN111243492B CN111243492B CN202010052190.7A CN202010052190A CN111243492B CN 111243492 B CN111243492 B CN 111243492B CN 202010052190 A CN202010052190 A CN 202010052190A CN 111243492 B CN111243492 B CN 111243492B
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- 238000000034 method Methods 0.000 title claims abstract description 24
- 239000003990 capacitor Substances 0.000 claims abstract description 30
- 238000004146 energy storage Methods 0.000 claims abstract description 15
- 238000004891 communication Methods 0.000 claims description 20
- 238000010586 diagram Methods 0.000 description 8
- 101150037603 cst-1 gene Proteins 0.000 description 5
- 239000010409 thin film Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000005669 field effect Effects 0.000 description 2
- 230000001808 coupling effect Effects 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
- G09G3/3275—Details of drivers for data electrodes
- G09G3/3291—Details of drivers for data electrodes in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
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- Control Of El Displays (AREA)
Abstract
The invention provides a pixel circuit, a pixel driving method and a display device. The pixel circuit comprises a light-emitting element, a driving circuit, an initialization circuit, a data writing circuit, a first energy storage circuit, a second energy storage circuit, a light-emitting control circuit, a potential control circuit and a voltage control circuit, wherein the data writing circuit is used for controlling the data voltage on the data line to be written into the control end of the driving circuit under the control of a first control signal; the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal provided by a third control end; the potential control circuit controls the control end of the driving circuit to be communicated with the first node under the control of a fourth control signal provided by a fourth control end. The invention reduces the capacitor charging process, can improve the display brightness uniformity, and can improve the brightness attenuation caused by the drift of the threshold voltage of the light-emitting element.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a pixel circuit, a pixel driving method, and a display device.
Background
In the conventional pixel circuit, the charging process of the capacitor cannot be reduced, and the influence of IR-Drop (IR Drop, which is a phenomenon indicating that the voltage drops or rises on the power supply and ground networks in the integrated circuit) of the power supply voltage provided from the power supply voltage terminal on the uniformity of the display luminance cannot be eliminated, and the problem of luminance degradation caused by the shift of the threshold voltage of the light emitting element cannot be improved.
Disclosure of Invention
The main objective of the present invention is to provide a pixel circuit, a pixel driving method and a display device, which solve the problems that in the prior art, a data write circuit cannot directly write a data voltage into a control terminal of a driving circuit, a capacitor charging process cannot be reduced, and the influence of IR-Drop (IR Drop, which is a phenomenon indicating that a voltage drops or rises on a power supply and a ground network in an integrated circuit) of a power supply voltage provided by a power supply voltage terminal on the display luminance uniformity cannot be eliminated, and the luminance decay caused by the drift of a threshold voltage of a light emitting element cannot be improved.
In order to achieve the above object, the present invention provides a pixel circuit including a light emitting element, a driving circuit, an initialization circuit, a data writing circuit, a first tank circuit, a second tank circuit, a light emission control circuit, a potential control circuit, and a voltage control circuit, wherein,
the first end of the first energy storage circuit is electrically connected with a first node, and the second end of the first energy storage circuit is electrically connected with the first end of the driving circuit; the first energy storage circuit is used for storing voltage;
a first end of the second tank circuit is electrically connected to the first node, and a second end of the second tank circuit is electrically connected to the second node; the second energy storage circuit is used for storing voltage;
the light-emitting control circuit is used for controlling the communication between the first end of the driving circuit and a power supply voltage end under the control of a first control signal provided by a first control end, and controlling the communication between the second end of the driving circuit and the first pole of the light-emitting element under the control of a second control signal provided by a second control end; the first electrode of the light-emitting element is electrically connected with the first voltage end;
the data writing circuit is used for controlling to write the data voltage on the data line into the control end of the driving circuit under the control of the first control signal;
the initialization circuit is used for controlling the communication between the first pole and the second node of the light-emitting element and controlling the communication between the first node and the initialization voltage end under the control of a third control signal provided by a third control end;
the drive circuit is used for generating a drive current flowing from a first end of the drive circuit to a second end of the drive circuit under the control of the potential of a control end of the drive circuit;
the voltage control circuit is used for controlling the communication between the second node and the second voltage end under the control of a third control signal provided by a third control end;
the potential control circuit is used for controlling the communication between the control end of the driving circuit and the first node under the control of a fourth control signal provided by a fourth control end.
In practice, the data writing circuit includes a data writing transistor;
the control electrode of the data writing transistor is electrically connected with the first control end, the first electrode of the data writing transistor is electrically connected with the data line, and the second electrode of the data writing transistor is electrically connected with the control end of the driving circuit.
In practice, the potential control circuit includes a potential control transistor;
and the control electrode of the potential control transistor is electrically connected with the fourth control end, the first electrode of the potential control transistor is electrically connected with the control end of the driving circuit, and the second electrode of the potential control transistor is electrically connected with the first node.
In practice, the voltage control circuit includes a voltage control transistor;
the control electrode of the voltage control transistor is electrically connected with the third control end, the first electrode of the voltage control transistor is electrically connected with the second node, and the second electrode of the voltage control transistor is electrically connected with the second voltage end.
In practice, the initialization circuit includes a first initialization transistor and a second initialization transistor;
a control electrode of the first initialization transistor is connected with the third control end, a first electrode of the first initialization transistor is electrically connected with the initialization voltage end, and a second electrode of the first initialization transistor is electrically connected with the first node;
a control electrode of the second initialization transistor is electrically connected to the third control terminal, a first electrode of the second initialization transistor is electrically connected to the first electrode of the light emitting element, and a second electrode of the second initialization transistor is electrically connected to the second node.
In practice, the light emission control circuit includes a first light emission control transistor and a second light emission control transistor;
a control electrode of the first light-emitting control transistor is electrically connected with the first control end, a first electrode of the first light-emitting control transistor is electrically connected with the power supply voltage end, and a second electrode of the first light-emitting control transistor is electrically connected with the first end of the driving circuit;
the control electrode of the second light-emitting control transistor is electrically connected with the second control end, the first electrode of the second light-emitting control transistor is electrically connected with the second end of the driving circuit, and the second electrode of the second light-emitting control transistor is electrically connected with the first electrode of the light-emitting element.
In practice, the first tank circuit includes a first storage capacitor, and the second tank circuit includes a second storage capacitor;
a first end of the first storage capacitor is electrically connected with a first node, and a second end of the first storage capacitor is electrically connected with a first end of the driving circuit;
the first end of the second storage capacitor is electrically connected with the first node, and the second end of the second storage capacitor is electrically connected with the second node.
In practice, the driving circuit includes a driving transistor, a control electrode of the driving transistor is a control end of the driving circuit, a first electrode of the driving transistor is a first end of the driving circuit, and a second electrode of the driving transistor is a second end of the driving circuit.
The invention also provides a pixel driving method, which is applied to the pixel circuit, wherein the display period comprises a compensation stage, a voltage holding stage and a light-emitting stage which are sequentially arranged; the pixel driving method includes:
in the compensation stage, the initialization circuit controls the first pole and the second node of the light-emitting element to be communicated under the control of a third control signal and controls the initialization voltage end to write initialization voltage into the first node; the data writing circuit controls the data line to write data voltage to the control end of the driving circuit under the control of the first control signal; the light-emitting control circuit controls the communication between the second end of the driving circuit and the first pole of the light-emitting element under the control of a second control signal;
in the voltage holding stage, the light-emitting control circuit controls the power supply voltage end to be communicated with the second end of the first energy storage circuit under the control of a first control signal, and the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal so as to correspondingly change the potential of the first node;
in the light emitting stage, the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal, the potential control circuit controls the control end of the driving circuit to be communicated with the first node under the control of a fourth control signal, the light emitting control circuit controls the power supply voltage end to be communicated with the first end of the driving circuit under the control of the first control signal, the light emitting control circuit controls the second end of the driving circuit to be communicated with the first voltage end under the control of the second control signal, and the driving circuit generates driving current flowing from the first end of the driving circuit to the second end of the driving circuit under the control of the potential of the control end of the driving circuit.
In implementation, the display period further comprises an initialization stage arranged before the compensation stage; the pixel driving method further includes:
in the initialization stage, the initialization circuit controls the first pole of the light emitting element to be communicated with the second node under the control of the third control signal, and controls the initialization voltage end to write the initialization voltage into the first node.
The invention also provides a display device which comprises the pixel circuit.
Compared with the prior art, in the pixel circuit, the pixel driving method and the display device, the data writing circuit directly writes the data voltage into the control end of the driving circuit in the compensation stage, so that the capacitor charging process is reduced, the influence of the IR voltage drop of the power voltage provided by the power voltage end on the display brightness uniformity can be eliminated, the brightness attenuation caused by the drift of the threshold voltage of the light-emitting element EL can be improved, and the influence of the threshold voltage of the driving transistor in the driving circuit on the display brightness uniformity can be eliminated.
Drawings
Fig. 1 is a structural diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of one embodiment of a pixel circuit according to the present invention;
FIG. 3 is a timing diagram illustrating operation of the pixel circuit according to the present invention;
FIG. 4A is a diagram illustrating the operation of the embodiment of the pixel circuit according to the invention in the initialization phase t 1;
fig. 4B is a schematic diagram illustrating the operation state of the embodiment of the pixel circuit according to the invention during the compensation phase t 2;
fig. 4C is a schematic diagram illustrating an operation state of the embodiment of the pixel circuit according to the invention in the voltage holding period t 3;
fig. 4D is a schematic diagram illustrating an operation state of the embodiment of the pixel circuit according to the invention during a light-emitting period t 4;
fig. 5 is a diagram illustrating a relationship between the driving current Ioled and the time t of the pixel circuit according to the embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 making any creative effort, shall fall within the protection scope of the present invention.
The transistors used in all embodiments of the present invention may be transistors, thin film transistors, or field effect transistors or other devices with the same characteristics. In the embodiment of the present invention, in order to distinguish two poles of the transistor except the control pole, one pole is called a first pole, and the other pole is called a second pole.
In practical operation, when the transistor is a triode, the control electrode may be a base electrode, the first electrode may be a collector electrode, and the second electrode may be an emitter electrode; alternatively, the control electrode may be a base electrode, the first electrode may be an emitter electrode, and the second electrode may be a collector electrode.
In practical operation, when the transistor is a thin film transistor or a field effect transistor, the control electrode may be a gate electrode, the first electrode may be a drain electrode, and the second electrode may be a source electrode; alternatively, the control electrode may be a gate electrode, the first electrode may be a source electrode, and the second electrode may be a drain electrode.
As shown in fig. 1, the pixel circuit according to the embodiment of the present invention includes a light emitting element EL, a driving circuit 11, a data writing circuit 12, a first tank circuit 13, a second tank circuit 14, a light emission control circuit 15, a potential control circuit 16, an initialization circuit 17, and a voltage control circuit 18, wherein,
a first end of the first tank circuit 13 is electrically connected to a first node b, and a second end of the first tank circuit 13 is electrically connected to a first end of the driving circuit 11; the first energy storage circuit 13 is used for storing voltage;
a first end of the second tank circuit 14 is electrically connected to the first node b, and a second end of the second tank circuit 14 is electrically connected to the second node a; the second tank circuit 14 is used for storing voltage;
the light-emitting control circuit 15 is electrically connected to the first control terminal S1, the second control terminal S2, the first terminal of the driving circuit 11, the second terminal of the driving circuit 11, the power voltage terminal and the first electrode of the light-emitting element EL, respectively, for controlling the communication between the first terminal of the driving circuit 11 and the power voltage terminal under the control of a first control signal provided by the first control terminal S1, and controlling the communication between the second terminal of the driving circuit 11 and the first electrode of the light-emitting element EL under the control of a second control signal provided by the second control terminal S2; a first electrode of the light emitting element EL is electrically connected to a first voltage terminal; the power supply voltage terminal is used for providing a power supply voltage VDD, and the first voltage terminal is used for providing a first voltage V1;
the initialization circuit 17 is electrically connected to the third control terminal S3, the first electrode of the light emitting element EL, the second node a, the initialization voltage terminal and the first node b, respectively, and is configured to control the first electrode of the light emitting element EL to communicate with the second node a and control the first node b to be electrically connected to the initialization voltage terminal under the control of a third control signal provided by the third control terminal S3; the initialization voltage end is used for providing initialization voltage Vinit;
the Data writing circuit 12 is electrically connected to the first control terminal S1, the Data line Data, and the control terminal of the driving circuit 11, respectively, and is configured to control writing of the Data voltage on the Data line Data into the control terminal of the driving circuit 11 under the control of the first control signal;
the driving circuit 11 is configured to generate a driving current flowing from a first terminal of the driving circuit 11 to a second terminal of the driving circuit 11 under the control of the potential of the control terminal thereof;
the potential control circuit 16 is electrically connected to a fourth control terminal S4, the control terminal of the driving circuit 11 and the first node b, respectively, for controlling the control terminal of the driving circuit 11 to be electrically connected to the first node b under the control of a fourth control signal provided by a fourth control terminal S4;
the voltage control circuit 18 is electrically connected to a third control terminal S3, the second node a and a second voltage terminal, and is configured to control the second node a and the second voltage terminal to be communicated with each other under the control of the third control signal; the second voltage terminal is used for providing a second voltage V2.
In a specific implementation, the light emitting element EL may be an organic light emitting diode, the first pole of the light emitting element EL may be an anode, and the second pole of the light emitting element EL may be a cathode, but not limited thereto.
In specific implementation, the first voltage V1 may be zero voltage or low voltage, but is not limited thereto.
Optionally, the second voltage V2 may also be zero voltage or low voltage, but is not limited thereto.
Optionally, the initialization voltage Vinit may also be zero voltage or low voltage, but is not limited thereto.
When the embodiment of the pixel circuit shown in fig. 1 of the present invention is in operation, in the compensation stage, the data write circuit 12 can directly write the data voltage Vdata into the control terminal of the driving circuit 11, so as to reduce the capacitor charging process, and eliminate the effect of IR-Drop (IR Drop, which is a phenomenon indicating that the voltage drops or rises on the power supply and ground network in the integrated circuit) of the power supply voltage provided by the power supply voltage terminal on the display luminance uniformity, and improve the luminance degradation caused by the drift of the threshold voltage of the light emitting element EL, and eliminate the effect of the threshold voltage of the driving transistor in the driving circuit on the display luminance uniformity.
When the embodiment of the pixel circuit shown in fig. 1 of the present invention is in operation, the display period includes a compensation stage, a voltage holding stage and a light emitting stage which are sequentially arranged;
in the compensation phase, the light-emitting control circuit 15 controls the communication between the second terminal of the driving circuit 11 and the first pole of the light-emitting element EL under the control of the second control signal; the initialization circuit 17 controls the first pole of the light emitting element EL to be connected to the second node a under the control of the third control signal, and controls the initialization voltage end to write the initialization voltage Vinit to the first node b; the Data writing circuit 12 controls the Data line Data to write the Data voltage Vdata to the control end of the driving circuit 11 under the control of the first control signal; at the beginning of the compensation phase, the driving circuit 11, under the control of its control terminal, turns on the connection between the first terminal of the driving circuit 11 and the second terminal of the driving circuit 11 to change the voltage of the first terminal of the driving circuit 11 accordingly until the driving circuit 11 turns off the connection between the first terminal of the driving circuit 11 and the second terminal of the driving circuit 11, at this time, the voltage of the first terminal of the driving circuit 11 may be Vdata-Vth, where Vth is the threshold voltage of the driving transistor of the driving circuit 11, so that the gate-source voltage of the driving transistor is independent of the threshold voltage of the driving transistor in the light emitting phase;
when the light emitting element EL is an organic light emitting diode, in the compensation phase, since the initialization circuit 17 controls the connection between the first pole of the light emitting element EL and the second node a, the voltage of the second node a may become V1+ Voled, so that in the light emitting phase, the gate-source voltage of the driving transistor is related to Voled, thereby improving the brightness attenuation caused by the drift of the threshold voltage of the light emitting element EL; voled is the threshold voltage of the organic light emitting diode;
in the voltage holding phase, the light-emitting control circuit 15 controls the communication between the power supply voltage end and the second end of the first energy storage circuit 13 under the control of the first control signal, and the voltage control circuit 18 controls the communication between the second node a and the second voltage end under the control of the third control signal so as to correspondingly change the potential of the first node b;
in the light emitting stage, the voltage control circuit 18 controls the connection between the second node a and the second voltage terminal under the control of the third control signal, the potential control circuit 16 controls the connection between the control terminal of the driving circuit 11 and the first node b under the control of the fourth control signal, the light emitting control circuit 15 controls the connection between the power supply voltage terminal and the first terminal of the driving circuit 11 under the control of the first control signal, the light emitting control circuit 15 controls the connection between the second terminal of the driving circuit 11 and the first voltage terminal under the control of the second control signal, and the driving circuit 11 generates the driving current flowing from the first terminal of the driving circuit 11 to the second terminal of the driving circuit 11 under the control of the potential of the control terminal of the driving circuit 11.
In a practical implementation, the display period may include an initialization phase arranged before the compensation phase, and when the embodiment of the pixel circuit of the invention as shown in fig. 1 is in operation,
in the initialization phase, the initialization circuit 17 controls the first pole of the light emitting element EL to communicate with the second node a under the control of the third control signal, and controls the initialization voltage terminal to write the initialization voltage Vinit to the first node b.
Specifically, the data write circuit may include a data write transistor;
the control electrode of the data writing transistor is electrically connected with the first control end, the first electrode of the data writing transistor is electrically connected with the data line, and the second electrode of the data writing transistor is electrically connected with the control end of the driving circuit.
Specifically, the potential control circuit may include a potential control transistor;
and the control electrode of the potential control transistor is electrically connected with the fourth control end, the first electrode of the potential control transistor is electrically connected with the control end of the driving circuit, and the second electrode of the potential control transistor is electrically connected with the first node.
Optionally, the voltage control circuit may include a voltage control transistor;
the control electrode of the voltage control transistor is electrically connected with the third control end, the first electrode of the voltage control transistor is electrically connected with the second node, and the second electrode of the voltage control transistor is electrically connected with the second voltage end.
Optionally, the initialization circuit may include a first initialization transistor and a second initialization transistor;
a control electrode of the first initialization transistor is connected with the third control end, a first electrode of the first initialization transistor is electrically connected with the initialization voltage end, and a second electrode of the first initialization transistor is electrically connected with the first node;
a control electrode of the second initialization transistor is electrically connected to the third control terminal, a first electrode of the second initialization transistor is electrically connected to the first electrode of the light emitting element, and a second electrode of the second initialization transistor is electrically connected to the second node.
In particular implementation, the light emission control circuit may include a first light emission control transistor and a second light emission control transistor;
a control electrode of the first light-emitting control transistor is electrically connected with the first control end, a first electrode of the first light-emitting control transistor is electrically connected with the power supply voltage end, and a second electrode of the first light-emitting control transistor is electrically connected with the first end of the driving circuit;
the control electrode of the second light-emitting control transistor is electrically connected with the second control end, the first electrode of the second light-emitting control transistor is electrically connected with the second end of the driving circuit, and the second electrode of the second light-emitting control transistor is electrically connected with the first electrode of the light-emitting element.
Specifically, the first tank circuit may include a first storage capacitor, and the second tank circuit may include a second storage capacitor;
a first end of the first storage capacitor is electrically connected with a first node, and a second end of the first storage capacitor is electrically connected with a first end of the driving circuit;
the first end of the second storage capacitor is electrically connected with the first node, and the second end of the second storage capacitor is electrically connected with the second node.
In a specific implementation, the driving circuit includes a driving transistor, a control terminal of the driving transistor is a control terminal of the driving circuit, a first terminal of the driving transistor is a first terminal of the driving circuit, and a second terminal of the driving transistor is a second terminal of the driving circuit.
The pixel circuit according to the present invention is described below with reference to a specific embodiment.
As shown in fig. 2, the pixel circuit according to the embodiment of the present invention includes an organic light emitting diode OLED, a driving circuit, a data writing circuit, a first tank circuit, a second tank circuit, a light emission control circuit, a potential control circuit, an initialization circuit, and a voltage control circuit,
the first tank circuit includes a first storage capacitor Cst1, and the second tank circuit includes a second storage capacitor Cst 2; the driving circuit includes a driving transistor T2, the data writing circuit includes a data writing transistor T7, the light emission control circuit includes a first light emission control transistor T1 and a second light emission control transistor T3; the potential control circuit includes a potential control transistor T6; the initialization circuit includes a first initialization transistor T8 and a second initialization transistor T5; the voltage control circuit comprises a voltage control transistor T4;
the gate of the Data writing transistor T7 is electrically connected to the first control terminal S1, the drain of the Data writing transistor T7 is electrically connected to the Data line Data, and the source of the Data writing transistor T7 is electrically connected to the gate of the driving transistor T2;
the gate of the potential control transistor T6 is electrically connected to the fourth control terminal S4, the drain of the potential control transistor T6 is electrically connected to the gate of the driving transistor T2, and the source of the potential control transistor T6 is electrically connected to the first node b;
the gate of the voltage control transistor T4 is electrically connected to the third control terminal S3, the drain of the voltage control transistor T4 is electrically connected to the second node a, and the source of the voltage control transistor T4 is electrically connected to the low voltage terminal; the low voltage end is used for providing a low voltage VSS;
the gate of the first initialization transistor T8 is connected to the third control terminal S3, the source of the first initialization transistor T8 is electrically connected to the low voltage terminal, and the drain of the first initialization transistor T8 is electrically connected to the first node b;
the gate electrode of the second initializing transistor T5 is electrically connected to the third control terminal S3, the source electrode of the second initializing transistor T5 is electrically connected to the anode electrode of the organic light emitting diode OLED, and the drain electrode of the second initializing transistor T5 is electrically connected to the second node a;
the gate electrode of the first light emitting control transistor T1 is electrically connected to the first control terminal S1, the source electrode of the first light emitting control transistor T1 is electrically connected to the power voltage terminal, and the drain electrode of the first light emitting control transistor T1 is electrically connected to the source electrode of the driving transistor T2;
the gate electrode of the second light emission controlling transistor T3 is electrically connected to the second control terminal S2, the source electrode of the second light emission controlling transistor T3 is electrically connected to the drain electrode of the driving transistor T2, and the drain electrode of the second light emission controlling transistor T3 is electrically connected to the anode electrode of the organic light emitting diode OLED;
a first terminal of the first storage capacitor Cst1 is electrically connected to the first node b, and a second terminal of the first storage capacitor Cst1 is electrically connected to the source electrode of the driving transistor T2;
a first terminal of the second storage capacitor Cst2 is electrically connected to the first node b, and a second terminal of the second storage capacitor Cst2 is electrically connected to the second node a.
In fig. 2, the third node d is a node electrically connected to the source of T2.
In the embodiment of the pixel circuit shown in fig. 2, T1, T2, T3, T8 and T5 are p-type thin film transistors, and T4, T6 and T7 are n-type thin film transistors, but not limited thereto.
In the embodiment of the pixel circuit shown in fig. 2, T2 is a driving transistor and the other transistors are switching transistors.
In the embodiment of the pixel circuit shown in fig. 2, the initialization voltage, the first voltage and the second voltage are all the low voltage VSS, but not limited thereto.
As shown in fig. 3, when the embodiment of the pixel circuit shown in fig. 2 of the present invention is in operation, the display period may include an initialization phase t1, a compensation phase t2, a voltage holding phase t3 and a light emitting phase t4, which are sequentially arranged;
in the initialization phase T1, S1 provides a low level, S2 provides a high level, S3 provides a low level, S4 provides a high level, as shown in fig. 4A, T1, T5 and T8 are all turned on to reset Cst1 and Cst2, so that the potential of the second node a becomes VSS + Voled, the potential of the first node b becomes VSS, and the potential of the third node d becomes VDD, so that at the beginning of the compensation phase T2, T2 can be turned on and the influence of the display data of the previous frame on the potentials of the nodes is eliminated; voled is the threshold voltage of the organic light emitting diode OLED;
at the compensation phase T2, S1 provides a high level, S2 provides a low level, S3 provides a low level, S4 provides a low level, Data provides a Data voltage Vdata, as shown in fig. 4B, T5, T8, T3 and T7 are turned on to write Vdata to the gate of T2, and at the beginning of the compensation phase T2, T2 is turned on to discharge Cst1 (the potential across Cst2 is not changed) to change the potential of the third node d until the potential of the third node d becomes Vdata-Vth, and T2 is turned off; wherein Vth is a threshold voltage of T2;
in the voltage holding phase S3, S1 provides a low level, S2 provides a high level, S3 provides a high level, and S4 provides a low level, as shown in fig. 4C, T1 and T4 are turned on, other transistors are turned off, the potential of the third node d jumps to VDD, the potential of the second node a jumps to VSS, the potential of the first node b jumps to VSS- (Vdata-Vth) + (VSS- (VSS + Voled)), the voltage variation of the third node d is Δ Vd, the voltage variation of the second node a is Δ Va, and the voltage variation of the first node b is Δ Vd + Δ Va due to the coupling effect of the capacitor;
in the light emitting period T4, S1 provides a low level, S2 provides a low level, S3 provides a high level, and S4 provides a high level, as shown in fig. 4D, T1, T2, T3, T4 and T6 are turned on, other transistors are turned off, the gate potential Vg of T2 is the potential of the third node D, Vg is equal to VSS + VDD-Vdata + Vth-Voled, the gate-source voltage Vgs of T2 is as follows:
Vgs＝VSS+VDD-Vdata+Vth-Voled-VDD＝VSS-Vdata+Vth-Voled；
t2 provides a drive current Ioled for the OLED, Ioled is as follows:
Ioled＝K(Vgs-Vth) 2 ＝(VSS-Vdata-Voled) 2 ；
k is a constant related to the process design of T2, and Ioled is unrelated to the threshold voltage of T2 and VDD, so that the OLED display is stable, the problems of uneven and unstable brightness are solved, and the influence of the IR voltage drop of VDD on the display uniformity is avoided; furthermore, Ioled is related to Voled, which alleviates the problem of brightness decay caused by Voled change (when Voled increases, Ioled increases accordingly, so that sufficient driving current can be supplied to prevent brightness decay).
In fig. 4A-4D, the transistors corresponding to the circles are indicated as being turned on at this stage.
As shown in FIG. 5, L1 is a graph showing the relationship between Ioled and time t when Vdata is equal to 5V, Vth is equal to 2V, and Voled is equal to 1.2V; l2 is a graph showing the relationship between Ioled and time t when Vdata is equal to 5V, Vth is equal to 105V, and Voled is equal to 1.5V; as can be seen from FIG. 5, the current offset is 10nA, and the effect of Vth and Voled changes on Ioled can be ignored.
The pixel driving method provided by the embodiment of the invention is applied to the pixel circuit, and the display period comprises a compensation stage, a voltage holding stage and a light-emitting stage which are sequentially arranged; the pixel driving method includes:
in the compensation stage, the initialization circuit controls the first pole of the light-emitting element to be communicated with the second node under the control of a third control signal and controls the initialization voltage end to write initialization voltage into the first node; the data writing circuit controls the data line to write data voltage to the control end of the driving circuit under the control of the first control signal; the light-emitting control circuit controls the communication between the second end of the driving circuit and the first pole of the light-emitting element under the control of a second control signal;
in the voltage holding stage, the light-emitting control circuit controls the power supply voltage end to be communicated with the second end of the first energy storage circuit under the control of a first control signal, and the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal so as to correspondingly change the potential of the first node;
in the light-emitting stage, the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal, the potential control circuit controls the control end of the driving circuit to be communicated with the first node under the control of a fourth control signal, the light-emitting control circuit controls the power supply voltage end to be communicated with the first end of the driving circuit under the control of a first control signal, the light-emitting control circuit controls the second end of the driving circuit to be communicated with the first voltage end under the control of a second control signal, and the driving circuit generates driving current flowing from the first end of the driving circuit to the second end of the driving circuit under the control of the potential of the control end of the driving circuit.
In the pixel driving method of the invention, in the compensation stage, the data writing circuit can directly write the data voltage into the control end of the driving circuit, thereby reducing the capacitance charging process, eliminating the influence of IR-Drop (IR voltage Drop) of the power voltage provided by the power voltage end on the display brightness uniformity, improving the brightness attenuation caused by the drift of the threshold voltage of the light-emitting element, and eliminating the influence of the threshold voltage of the driving transistor in the driving circuit on the display brightness uniformity.
Specifically, the display period may further include an initialization stage arranged before the compensation stage; the pixel driving method may further include:
in the initialization stage, the initialization circuit controls the first pole of the light-emitting element to be communicated with the second node under the control of the third control signal, and controls the initialization voltage end to write the initialization voltage into the first node.
The display device provided by the embodiment of the invention comprises the pixel circuit.
The display device provided by the embodiment of the invention comprises the pixel circuit.
The display device provided by the embodiment of the invention can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (11)
1. A pixel circuit includes a light emitting element, a driving circuit, an initialization circuit, a data writing circuit, a first tank circuit, a second tank circuit, a light emission control circuit, a potential control circuit, and a voltage control circuit,
the first end of the first energy storage circuit is electrically connected with a first node, and the second end of the first energy storage circuit is electrically connected with the first end of the driving circuit; the first energy storage circuit is used for storing voltage;
a first end of the second tank circuit is electrically connected with the first node, and a second end of the second tank circuit is electrically connected with the second node; the second energy storage circuit is used for storing voltage;
the light-emitting control circuit is used for controlling the communication between the first end of the driving circuit and a power supply voltage end under the control of a first control signal provided by the first control end, and controlling the communication between the second end of the driving circuit and the first pole of the light-emitting element under the control of a second control signal provided by the second control end; the second pole of the light-emitting element is electrically connected with the first voltage end;
the data writing circuit is used for controlling to write the data voltage on the data line into the control end of the driving circuit under the control of the first control signal;
the initialization circuit is used for controlling the communication between the first pole and the second node of the light-emitting element and controlling the communication between the first node and the initialization voltage end under the control of a third control signal provided by a third control end;
the drive circuit is used for generating a drive current flowing from a first end of the drive circuit to a second end of the drive circuit under the control of the potential of a control end of the drive circuit;
the voltage control circuit is used for controlling the communication between the second node and the second voltage end under the control of a third control signal provided by a third control end;
the potential control circuit is used for controlling the communication between the control end of the driving circuit and the first node under the control of a fourth control signal provided by a fourth control end.
2. The pixel circuit according to claim 1, wherein the data writing circuit includes a data writing transistor;
the control electrode of the data writing transistor is electrically connected with the first control end, the first electrode of the data writing transistor is electrically connected with the data line, and the second electrode of the data writing transistor is electrically connected with the control end of the driving circuit.
3. The pixel circuit according to claim 1, wherein the potential control circuit includes a potential control transistor;
the control electrode of the potential control transistor is electrically connected with the fourth control end, the first electrode of the potential control transistor is electrically connected with the control end of the driving circuit, and the second electrode of the potential control transistor is electrically connected with the first node.
4. The pixel circuit according to claim 1, wherein the voltage control circuit comprises a voltage control transistor;
and the control electrode of the voltage control transistor is electrically connected with the third control end, the first electrode of the voltage control transistor is electrically connected with the second node, and the second electrode of the voltage control transistor is electrically connected with the second voltage end.
5. The pixel circuit according to claim 1, wherein the initialization circuit includes a first initialization transistor and a second initialization transistor;
a control electrode of the first initialization transistor is connected with the third control end, a first electrode of the first initialization transistor is electrically connected with the initialization voltage end, and a second electrode of the first initialization transistor is electrically connected with the first node;
a control electrode of the second initialization transistor is electrically connected to the third control terminal, a first electrode of the second initialization transistor is electrically connected to the first electrode of the light emitting element, and a second electrode of the second initialization transistor is electrically connected to the second node.
6. The pixel circuit according to claim 1, wherein the light emission control circuit includes a first light emission control transistor and a second light emission control transistor;
a control electrode of the first light-emitting control transistor is electrically connected with the first control end, a first electrode of the first light-emitting control transistor is electrically connected with the power supply voltage end, and a second electrode of the first light-emitting control transistor is electrically connected with a first end of the driving circuit;
the control electrode of the second light-emitting control transistor is electrically connected with the second control end, the first electrode of the second light-emitting control transistor is electrically connected with the second end of the driving circuit, and the second electrode of the second light-emitting control transistor is electrically connected with the first electrode of the light-emitting element.
7. The pixel circuit according to claim 1, wherein the first tank circuit comprises a first storage capacitor and the second tank circuit comprises a second storage capacitor;
a first end of the first storage capacitor is electrically connected with a first node, and a second end of the first storage capacitor is electrically connected with a first end of the driving circuit;
the first end of the second storage capacitor is electrically connected with the first node, and the second end of the second storage capacitor is electrically connected with the second node.
8. The pixel circuit according to claim 1, wherein the driving circuit comprises a driving transistor, a control terminal of the driving transistor is a control terminal of the driving circuit, a first terminal of the driving transistor is a first terminal of the driving circuit, and a second terminal of the driving transistor is a second terminal of the driving circuit.
9. A pixel driving method applied to the pixel circuit according to any one of claims 1 to 8, wherein the display period includes a compensation phase, a voltage holding phase and a light emitting phase which are sequentially arranged; the pixel driving method includes:
in the compensation stage, the initialization circuit controls the first pole and the second node of the light-emitting element to be communicated under the control of a third control signal and controls the initialization voltage end to write initialization voltage into the first node; the data writing circuit controls the data line to write data voltage into the control end of the driving circuit under the control of the first control signal; the light-emitting control circuit controls the communication between the second end of the driving circuit and the first pole of the light-emitting element under the control of a second control signal;
in the voltage holding stage, the light-emitting control circuit controls the power supply voltage end to be communicated with the second end of the first energy storage circuit under the control of a first control signal, and the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal so as to correspondingly change the potential of the first node;
in the light emitting stage, the voltage control circuit controls the second node to be communicated with the second voltage end under the control of a third control signal, the potential control circuit controls the control end of the driving circuit to be communicated with the first node under the control of a fourth control signal, the light emitting control circuit controls the power supply voltage end to be communicated with the first end of the driving circuit under the control of the first control signal, the light emitting control circuit controls the second end of the driving circuit to be communicated with the first voltage end under the control of the second control signal, and the driving circuit generates driving current flowing from the first end of the driving circuit to the second end of the driving circuit under the control of the potential of the control end of the driving circuit.
10. The pixel driving method according to claim 9, wherein the display period further includes an initialization phase disposed before the compensation phase; the pixel driving method further includes:
in the initialization stage, the initialization circuit controls the first pole of the light emitting element to be communicated with the second node under the control of the third control signal, and controls the initialization voltage end to write the initialization voltage into the first node.
11. A display device comprising the pixel circuit according to any one of claims 1 to 8.
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| CN119446037A (en) * | 2023-07-31 | 2025-02-14 | 京东方科技集团股份有限公司 | Pixel circuit, driving method and display device |
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