CN111508420A - Pixel circuit and driving method thereof - Google Patents
Pixel circuit and driving method thereof Download PDFInfo
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- CN111508420A CN111508420A CN202010304374.8A CN202010304374A CN111508420A CN 111508420 A CN111508420 A CN 111508420A CN 202010304374 A CN202010304374 A CN 202010304374A CN 111508420 A CN111508420 A CN 111508420A
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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]
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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]
- G09G3/3225—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] using an active matrix
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- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
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- Electroluminescent Light Sources (AREA)
- Control Of El Displays (AREA)
Abstract
The application discloses a pixel circuit and a driving method thereof, comprising a light-emitting device, a driving transistor, a switch module, a compensation module and an initialization module; in a data signal writing phase, the data signal is written into the grid electrode of the driving transistor and the compensation module, and the compensation module maintains the grid electrode voltage of the driving transistor and compensates the drift of the threshold voltage in the driving transistor; the initialization module initializes the light emitting device; in a light emitting stage, a light emitting signal loaded by the light emitting signal line enables the switch module and the initialization module to work, the compensation module maintains the conduction of the driving transistor to drive the light emitting device to emit light, and the initialization module writes the initialization signal into the compensation module to ensure the light emitting stability of the light emitting device.
Description
Technical Field
The present disclosure relates to display technologies, and particularly to a pixel circuit and a driving method thereof.
Background
Organic light emitting devices are classified into a current driving type and a voltage driving type according to a method of driving an Electroluminescent (E L) element, but a voltage between a gate and a source of the organic light emitting device may drift with time, and a current flowing through the element may vary, so that a display device may have a problem of display unevenness.
Disclosure of Invention
The embodiment of the application provides a pixel circuit and a driving method thereof, which can compensate the threshold voltage of a driving transistor and ensure the light emitting stability of a light emitting device.
The present application provides a pixel circuit, including: the device comprises a light-emitting device, a driving transistor, a switch module, a compensation module and an initialization module;
one pole of the light-emitting device is connected to a first common voltage end, and the other pole of the light-emitting device is connected with the second pole of the driving transistor through the switch module;
the first pole of the driving transistor is connected with a second common voltage end and a data signal through the switch module, and the driving transistor is used for driving the light-emitting device to emit light in a light-emitting stage according to the data signal written in a data signal writing stage; the grid electrode and the second pole of the driving transistor are connected with the compensation module so as to compensate the threshold voltage of the driving transistor;
the switch module is connected with the scanning line, the light-emitting signal line, the data signal and the second common voltage end, and is used for writing the data signal into the first pole of the driving transistor in the data signal writing stage and compensating the threshold voltage of the driving transistor through the compensation module; writing an initialization signal into the compensation module through the initialization module in the light-emitting stage, and enabling the light-emitting device to emit light;
the compensation module is connected with the second common voltage end and the scanning line and is used for compensating the threshold voltage of the driving transistor;
the initialization module is connected with the scanning line and the light-emitting signal line, and is used for initializing the light-emitting device in the data signal writing stage and writing the initialization signal in the compensation module in the light-emitting stage.
In some embodiments, the compensation module comprises a first transistor, a second transistor, a first storage capacitor, and a second storage capacitor;
the grid electrode of the first transistor is connected with the scanning line, the first pole of the first transistor is connected with the second pole of the driving transistor, and the second pole of the first transistor is connected with the grid electrode of the driving transistor; the first transistor is used for compensating the threshold voltage of the driving transistor in the data signal writing phase;
a gate of the second transistor is connected to the scan line, a first pole of the second transistor is connected to a second pole of the first storage capacitor, and a second pole of the second transistor is connected to a gate of the driving transistor; the second transistor is used for controlling storage signals of the first storage capacitor and the second storage capacitor so as to maintain the grid voltage of the driving transistor;
the first pole of the first storage capacitor is connected to the second common voltage end;
and the first pole of the second storage capacitor is connected to the second common voltage end, and the second pole of the second storage capacitor is connected with the second pole of the second transistor.
In some embodiments, the initialization module includes a third transistor and a fourth transistor;
a gate of the third transistor is connected to the light emitting signal line, a first pole of the third transistor is connected to a first pole of the second transistor, and a second pole of the third transistor is connected to the initialization signal;
the grid electrode of the fourth transistor is connected with the scanning line, the first pole of the fourth transistor is connected with the initialization signal, and the second pole of the fourth transistor is connected with the first pole of the light-emitting device.
In some embodiments, the switch module includes a fifth transistor, a sixth transistor, a seventh transistor;
a gate of the fifth transistor is connected to the scan line, a first pole of the fifth transistor is connected to the data signal, and a second pole of the fifth transistor is connected to the first pole of the driving transistor;
a gate of the sixth transistor is connected to the light emitting signal line, a first pole of the sixth transistor is connected to the second common voltage terminal, and a second pole of the sixth transistor is connected to the first pole of the driving transistor;
a gate of the seventh transistor is connected to the light emitting signal line, a first pole of the seventh transistor is connected to the second pole of the driving transistor, and a second pole of the seventh transistor is connected to the first pole of the light emitting device.
In some embodiments, the first common voltage terminal is a dc low power supply, and the second common voltage terminal is a dc high power supply.
In some embodiments, the initialization signal is a dc low power supply.
In some embodiments, the light emitting device is a light emitting diode.
In some embodiments, the light emitting device includes sub-millimeter light emitting diodes, micro light emitting diodes, and organic light emitting diodes.
The present application further provides a pixel driving method for driving the pixel circuit, the pixel driving method including:
in a data signal writing stage, a scanning signal loaded by the scanning line enables the switch module, the compensation module and the initialization module to work so as to write the data signal into the grid electrode of the driving transistor and the compensation module, and the compensation module maintains the grid electrode voltage of the driving transistor and compensates the drift of the threshold voltage in the driving transistor; the initialization module initializes the light emitting device;
in a light emitting stage, a light emitting signal loaded by the light emitting signal line enables the switch module and the initialization module to work, the compensation module maintains the conduction of the driving transistor to drive the light emitting device to emit light, and the initialization module writes the initialization signal into the compensation module.
The present application also provides a pixel circuit, comprising:
a light emitting device, the cathode of which is connected to a common ground voltage terminal;
the upper pole plate of the first storage capacitor is connected to a power supply voltage end;
the upper pole plate of the second storage capacitor is connected to a power supply voltage end;
a grid electrode of the first transistor is connected with a scanning line, a source electrode of the first transistor is connected with a drain electrode of the eighth transistor, and the drain electrode of the first transistor is connected with a lower polar plate of the second storage capacitor;
a gate of the second transistor is connected with the scan line, a source of the second transistor is connected with a lower plate of the first storage capacitor, and a drain of the second transistor is connected with a lower plate of the second storage capacitor;
a third transistor, a gate of which is connected to a light emitting signal line, a source of which is connected to a source of the second transistor, and a drain of which is connected to an initialization voltage terminal;
a fourth transistor, a gate of which is connected to the scan line, a source of which is connected to the initialization voltage terminal, and a drain of which is connected to an anode of the light emitting device;
a gate of the fifth transistor is connected to the scan line, a source of the fifth transistor is connected to the data line, and a drain of the fifth transistor is connected to the source of the eighth transistor;
a sixth transistor, a gate of which is connected to the light emitting signal line, a source of which is connected to a power supply voltage terminal, and a drain of which is connected to a drain of the fifth transistor;
a seventh transistor, a gate of which is connected to the light emitting signal line, a source of which is connected to the source of the first transistor, and a drain of which is connected to an anode of the light emitting device;
and a gate of the eighth transistor is connected to the drain of the first transistor, a source of the eighth transistor is connected to the drain of the fifth transistor, and a drain of the eighth transistor is connected to the source of the seventh transistor.
The pixel circuit and the driving method thereof provided by the embodiment of the application comprise a light-emitting device, a driving transistor, a switch module, a compensation module and an initialization module; in a data signal writing phase, the data signal is written into the grid electrode of the driving transistor and the compensation module, and the compensation module maintains the grid electrode voltage of the driving transistor and compensates the drift of the threshold voltage in the driving transistor; the initialization module initializes the light emitting device; in a light emitting stage, a light emitting signal loaded by the light emitting signal line enables the switch module and the initialization module to work, the compensation module maintains the conduction of the driving transistor to drive the light emitting device to emit light, and the initialization module writes the initialization signal into the compensation module to ensure the light emitting stability of the light emitting device.
Drawings
The technical solution and other advantages of the present application will become apparent from the detailed description of the embodiments of the present application with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a pixel circuit provided by an embodiment of the present application;
fig. 2A is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure;
FIG. 2B is a timing diagram illustrating the operation of the pixel circuit shown in FIG. 2A;
fig. 3 is a schematic structural diagram of a pixel circuit according to an embodiment of the present application.
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. It is to be understood that the embodiments described are only a few embodiments of the present application and not all 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 application.
In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.
Specifically, please refer to fig. 1, which is a schematic diagram of a pixel circuit provided in the present embodiment, wherein the pixel circuit includes a light emitting device L ED, a driving transistor Td, a switch module 101, a compensation module 102, and an initialization module 103;
one electrode of the light emitting device L ED is connected to a first common voltage terminal VSS, and the other electrode of the light emitting device L ED is connected to the second electrode of the driving transistor Td through the switching module 101;
a first pole of the driving transistor Td is connected to a second common voltage terminal VDD and a data signal Vdata through the switch module 101, the driving transistor Td is used for driving the light emitting device L ED to emit light according to the data signal Vdata written in the data signal writing stage S1 in the light emitting stage S2;
the switch module 101 is connected to a scan line scan (n), a light emitting signal line em (n), the data signal Vdata, and the second common voltage terminal VDD, and the switch module 101 is configured to write the data signal Vdata into the first electrode of the driving transistor Td in a data signal writing phase S1 and compensate the threshold voltage Vth of the driving transistor Td through the compensation module 102, and write an initialization signal VI into the compensation module 102 through the initialization module 103 in the light emitting phase S2 and enable the light emitting device L ED to emit light;
the compensation module 102 is connected to the second common voltage terminal VDD and the scan line scan (n), and the compensation module 102 is configured to compensate for the threshold voltage Vth of the driving transistor Td;
the initialization module 103 is connected to the scan line scan (n) and the light emitting signal line em (n), the initialization module 103 is configured to initialize the light emitting device L ED during the data signal writing phase S1, and write the initialization signal VI for the compensation module 102 during the light emitting phase S2.
In the pixel circuit provided by the embodiment of the application, in the data signal writing stage S1, the gate voltage of the driving transistor Td is maintained through the switch module 101 and the compensation module 102, and the threshold voltage Vth of the driving transistor Td is compensated, in the light emitting stage S2, the initialization signal VI is written into the compensation module 102 through the switch module 101 and the initialization module 103, the driving transistor Td is maintained to be turned on through the compensation module 102, and the light emitting device L ED is driven to emit light, so that the stability of the light emission of the light emitting device is ensured.
In addition, since only the scan lines scan (n) and the light emitting signal lines em (n) are involved in the pixel circuit, the density of the flat cables can be reduced, defects of dot lines due to film residues can be reduced, the response speed and the refresh rate can be improved, and the production cost can be reduced.
The first common voltage terminal VSS is a dc low power supply, and the second common voltage terminal VDD is a dc high power supply. Specifically, the first common voltage terminal VSS is-1V to-5V; further, the first common voltage terminal VSS is-2.55V.
The initialization signal VI is a direct-current low power supply; specifically, the initialization signal VI is-3V to-5V.
The light emitting device L ED is a light emitting diode, and specifically, the light emitting device L ED includes a submillimeter light emitting diode (Mini-L ED), a Micro light emitting diode (Micro-L ED), and an organic light emitting diode (O L ED).
In this embodiment, the light emitting devices L ED are connected to the common cathode, specifically, referring to fig. 1, one of the light emitting devices L ED connected to the first common voltage terminal VSS is a cathode, and one of the light emitting devices L ED connected to the second electrode of the driving transistor Td through the switch module 101 is an anode.
The transistor adopted in the embodiment of the application comprises a thin film transistor and a field effect transistor; to distinguish between a source and a drain in a transistor, except for a gate, a first pole of the present application may be one of the drain or the source, and correspondingly, a second pole may be the other of the source or the drain.
The present application further provides a pixel driving method for driving the pixel circuit, the pixel driving method including:
in a data signal writing stage S1, the scan signal loaded by the scan line scan (n) causes the switch module 101, the compensation module 102, and the initialization module 103 to operate to write the data signal Vdata to the gate of the driving transistor Td and the compensation module 102, the compensation module 102 maintains the gate voltage of the driving transistor Td and compensates for the shift of the threshold voltage Vth in the driving transistor Td;
in the light emitting period S2, the light emitting signal loaded by the light emitting signal line em (n) makes the switch module 101 and the initialization module 103 operate, the compensation module 101 maintains the driving transistor Td turned on, the light emitting device L ED is driven to emit light, and the initialization module 103 writes the initialization signal VI into the compensation module 102.
Referring to fig. 2A, which is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure, the compensation module 102 includes a first transistor T1, a second transistor T2, a first storage capacitor C1, and a second storage capacitor C2;
the gate electrode of the first transistor T1 is connected to the scan line scan (n), the first pole of the first transistor T1 is connected to the second pole of the driving transistor Td, and the second pole of the first transistor T1 is connected to the gate electrode of the driving transistor Td; the first transistor T1 for compensating a threshold voltage Vth of the driving transistor Td during the data signal writing phase S1;
a gate electrode of the second transistor T2 is connected to the scan line scan (n), a first electrode of the second transistor T2 is connected to the second electrode of the first storage capacitor C1, and a second electrode of the second transistor T2 is connected to the gate electrode of the driving transistor Td; the second transistor T2 is used to control the storage signals of the first and second storage capacitors C1 and C2 to maintain the gate voltage of the driving transistor Td;
a first pole of the first storage capacitor C1 is connected to the second common voltage terminal VDD;
a first pole of the second storage capacitor C2 is connected to the second common voltage terminal VDD, and a second pole of the second storage capacitor C2 is connected to a second pole of the second transistor T2.
With continued reference to fig. 2A, the initialization module 102 includes a third transistor T3 and a fourth transistor T4;
a gate of the third transistor T3 is connected to the light emitting signal line em (n), a first pole of the third transistor T3 is connected to a first pole of the second transistor T2, and a second pole of the third transistor T3 is connected to the initialization signal VI;
a gate of the fourth transistor T4 is connected to the scan line scan (n), a first electrode of the fourth transistor T4 is connected to the initialization signal VI, and a second electrode of the fourth transistor T4 is connected to a first electrode of the light emitting device L ED.
With continued reference to fig. 2A, the switch module 101 includes a fifth transistor T5, a sixth transistor T6, and a seventh transistor T7;
a gate of the fifth transistor T5 is connected to the scan line scan (n), a first pole of the fifth transistor T5 is connected to the data signal Vdata, and a second pole of the fifth transistor T5 is connected to a first pole of the driving transistor Td;
a gate of the sixth transistor T6 is connected to the light emitting signal line em (n), a first pole of the sixth transistor T6 is connected to the second common voltage terminal VDD, and a second pole of the sixth transistor T6 is connected to the first pole of the driving transistor Td;
a gate of the seventh transistor T7 is connected to the light emitting signal line em (n), a first pole of the seventh transistor T7 is connected to the second pole of the driving transistor Td, and a second pole of the seventh transistor T7 is connected to the first pole of the light emitting device L ED.
Please refer to fig. 2B, which is a timing diagram illustrating the operation of the pixel circuit shown in fig. 2A; where Vgate denotes the gate voltage. In each refresh period (1frame), two phases are included, namely a data signal writing phase S1 and a light emitting phase S2.
At the data signal writing stage S1: when the scan signal loaded on the scan line scan (n) is at a low level, the fifth transistor T5 in the switch module 101 is turned on, the first transistor T1 and the second transistor T2 in the compensation module 102 are turned on, and the fourth transistor T4 in the initialization module 103 is turned on; the data signal Vdata is written into the first pole of the driving transistor Td and charges the first storage capacitor C1 and the second storage capacitor C2 in the compensation module 102, when the difference Vgs between the gate potential Vg and the first pole Vs of the driving transistor Td is smaller than the threshold voltage Vth of the driving transistor Td, the driving transistor Td is turned on, and the compensation module 102 maintains the gate voltage of the driving transistor Td to compensate for the threshold voltage Vth of the driving transistor Td.
Specifically, since the second pole of the first storage capacitor C1 writes the initialization signal VI in the previous stage (i.e., the light emitting stage S2), when the second transistor T2 is turned on, the first storage capacitor C1 releases the initialization signal VI stored in the previous stage (i.e., the light emitting stage S2), the second transistor T2 is charged by the initialization signal VI released by the first storage capacitor C1, the gate potential Vg of the driving transistor Td continuously decreases until the driving transistor Td is turned on, that is, Vgs Vg-Vs < Vth, when the difference Vgs between the gate potential Vg and the first electrode potential Vs of the driving transistor Td is less than the threshold voltage Vth of the driving transistor Td, and the driving transistor Td is turned on. The driving transistor Td is turned on, the data signal Vdata charges the first and second storage capacitors C1 and C2, and the data signal Vdata neutralizes the signals stored in the first and second storage capacitors C1 and C2, so that the gate potential Vg of the driving transistor Td is maintained, thereby compensating for the threshold voltage Vth of the driving transistor Td.
Ideally, when the difference Vgs between the gate potential Vg and the first electrode potential Vs of the driving transistor Td is equal to the threshold voltage Vth of the driving transistor Td, the driving transistor Td is turned on, i.e., Vgs is Vg-Vs is Vth, and the driving transistor Td is turned on. When the fifth transistor T5 is turned on, the data signals Vdata and Vg-Vs written into the first electrode of the driving transistor Td are obtained as Vth: Vg-Vdata is Vth.
The fourth transistor T4 is turned on, and can reset the light emitting device L ED, so as to prevent the first electrode of the light emitting device from remaining the signal written in the previous stage (i.e., the light emitting stage S2) in the data signal writing stage S1, which causes the light emitting device L ED to emit weak light in the data signal writing stage S1, thereby affecting the contrast.
In this case, the light emitting signal line em (n) is loaded to be at a high level in the data signal writing stage S1, the sixth transistor T6 and the seventh transistor T7 of the switch module 101 are turned off, and the third transistor T3 of the initialization module 103 is turned off.
In the light emitting stage S2, when a light emitting signal loaded on the light emitting signal line em (n) is at a low level, the sixth transistor T6 and the seventh transistor T7 of the switch module 101 are turned on, the third transistor T3 of the initialization module 103 is turned on, the initialization signal VI is written into the first electrode of the second transistor T2 of the compensation module 102, the first storage capacitor C1 stores the initialization signal VI, the second storage capacitor C2 keeps the driving transistor Td turned on through the sixth transistor T6, and the seventh transistor T7 is turned on, so that the driving transistor Td generates a driving current I to drive the light emitting device L ED to emit light.
Wherein, the scan signal loaded on the scan signal line scan (n) is at a high level in the light emitting period S2, the fifth transistor T5 in the switch module 101 is turned off, the first transistor T1 and the second transistor T2 in the compensation module 102 are turned off, and the fourth transistor T4 in the initialization module 103 is turned off.
When the sixth transistor T6 is turned on, the first common voltage signal VDD is written into the first pole of the driving transistor Td, and the difference Vgs between the gate potential Vg and the first pole potential Vs of the driving transistor Td is equal to Vg-VDD; therefore, the drive current I is (C) defined by Vg-Vdata Vth, Vgs Vg-VDD, and Vg-VdataoxμmW/L)*(Vgs-Vth)2/2 (wherein, Cox、μmW, L are the channel capacitance per unit area, channel mobility, channel width, and channel length of the transistor, respectively, and the drive current I ═ C (C)oxμmW/L)*(Vg-VDD-Vg+Vdata)2/2＝(CoxμmW/L)*(Vdata-VDD)2And/2, so that the driving current I is not affected by the variation of the threshold voltage Vth, the light emitting device L ED can ensure the stability of light emission.
Please refer to fig. 3, which is a schematic structural diagram of a pixel circuit according to an embodiment of the present disclosure; the present application also provides a pixel circuit, comprising:
a light emitting device L ED, a cathode of the light emitting device L ED being connected to a common ground voltage terminal VSS;
the upper plate of the first storage capacitor C1 is connected to a power supply voltage end VDD;
the upper plate of the second storage capacitor C2 is connected to a power supply voltage end VDD;
a first transistor T1, a gate of the first transistor T1 being connected to a scan line scan (n), a source S1 of the first transistor T1 being connected to a drain D8 of an eighth transistor T8, a drain D1 of the first transistor T1 being connected to a lower plate of the second storage capacitor C2;
a second transistor T2, a gate of the second transistor T2 being connected to the scan line scan (n), a source S2 of the second transistor T2 being connected to a lower plate of the first storage capacitor C1, and a drain D2 of the second transistor T2 being connected to a lower plate of the second storage capacitor C2;
a third transistor T3, a gate of the third transistor T3 is connected to the light emitting signal line em (n), a source S3 of the third transistor T3 is connected to a source S2 of the second transistor T2, and a drain D3 of the third transistor T3 is connected to the initialization voltage terminal VI;
a fourth transistor T4, a gate of the fourth transistor T4 being connected to the scan line scan (n), a source S4 of the fourth transistor T4 being connected to the initialization voltage terminal VI, a drain D4 of the fourth transistor T4 being connected to an anode of the light emitting device L ED;
a fifth transistor T5, a gate of the fifth transistor T5 being connected to the scan line scan (n), a source S5 of the fifth transistor T5 being connected to the data line Vdata, and a drain D5 of the fifth transistor T5 being connected to a source S8 of the eighth transistor T8;
a sixth transistor T6, a gate of the sixth transistor T6 being connected to the light emitting signal line em (n), a source S6 of the sixth transistor T6 being connected to the power supply voltage terminal VDD, a drain D6 of the sixth transistor T6 being connected to a drain D5 of the fifth transistor T5;
a seventh transistor T7, a gate of the seventh transistor T7 being connected to the light emitting signal line em (n), a source S7 of the seventh transistor T7 being connected to the source S1 of the first transistor T1, a drain D7 of the seventh transistor T7 being connected to an anode of the light emitting device L ED;
and an eighth transistor T8, a gate of the eighth transistor T8 being connected to the drain D1 of the first transistor T1, a source S8 of the eighth transistor T8 being connected to the drain D5 of the fifth transistor T5, and a drain D8 of the eighth transistor T8 being connected to the source S7 of the seventh transistor T7.
In the pixel circuits in the embodiments of the present application, P-type transistors are used for illustration, and those skilled in the art can replace P-type transistors with N-type transistors, and accordingly, the phase of the signal is inverted to obtain the analysis result. Therefore, the pixel circuit using the N-type transistor and the driving method thereof are not described in detail herein in the embodiments of the present application.
The pixel circuit and the driving method thereof provided by the embodiment of the application comprise a light emitting device L ED, a driving transistor Td, a switch module 101, a compensation module 102 and an initialization module 103, wherein in a data signal writing phase S1, a data signal Vdata is written into a gate of the driving transistor Td and the compensation module 102, the compensation module 102 maintains a gate voltage of the driving transistor Td and compensates for a drift of a threshold voltage Vth in the driving transistor Td, the initialization module 103 initializes the light emitting device L ED, in a light emitting phase S2, a light emitting signal loaded by a light emitting signal line EM (n) enables the switch module 101 and the initialization module 103 to work, the compensation module 103 maintains the driving transistor Td to be turned on to drive the light emitting device L ED to emit light, and the initialization module 103 writes the initialization signal VI into the compensation module 103 to ensure stability of light emission of the light emitting device L ED.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The pixel circuit and the driving method thereof provided by the embodiments of the present application are described in detail above, and a specific example is applied in the description to explain the principle and the implementation of the present application, and the description of the embodiments above is only used to help understanding the technical solution and the core idea of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.
Claims (10)
1. A pixel circuit, comprising: the device comprises a light-emitting device, a driving transistor, a switch module, a compensation module and an initialization module;
one pole of the light-emitting device is connected to a first common voltage end, and the other pole of the light-emitting device is connected with the second pole of the driving transistor through the switch module;
the first pole of the driving transistor is connected with a second common voltage end and a data signal through the switch module, and the driving transistor is used for driving the light-emitting device to emit light in a light-emitting stage according to the data signal written in a data signal writing stage; the grid electrode and the second pole of the driving transistor are connected with the compensation module so as to compensate the threshold voltage of the driving transistor;
the switch module is connected with the scanning line, the light-emitting signal line, the data signal and the second common voltage end, and is used for writing the data signal into the first pole of the driving transistor in the data signal writing stage and compensating the threshold voltage of the driving transistor through the compensation module; enabling the light-emitting device to emit light in the light-emitting stage, and writing an initialization signal into the compensation module through the initialization module;
the compensation module is connected with the second common voltage end and the scanning line and is used for compensating the threshold voltage of the driving transistor;
the initialization module is connected with the scanning line and the light-emitting signal line, and is used for initializing the light-emitting device in the data signal writing stage and writing the initialization signal in the compensation module in the light-emitting stage.
2. The pixel circuit according to claim 1, wherein the compensation module comprises a first transistor, a second transistor, a first storage capacitor and a second storage capacitor;
the grid electrode of the first transistor is connected with the scanning line, the first pole of the first transistor is connected with the second pole of the driving transistor, and the second pole of the first transistor is connected with the grid electrode of the driving transistor; the first transistor is used for compensating the threshold voltage of the driving transistor in the data signal writing phase;
a gate of the second transistor is connected to the scan line, a first pole of the second transistor is connected to a second pole of the first storage capacitor, and a second pole of the second transistor is connected to a gate of the driving transistor; the second transistor is used for controlling storage signals of the first storage capacitor and the second storage capacitor so as to maintain the grid voltage of the driving transistor;
the first pole of the first storage capacitor is connected to the second common voltage end;
and the first pole of the second storage capacitor is connected to the second common voltage end, and the second pole of the second storage capacitor is connected with the second pole of the second transistor.
3. The pixel circuit according to claim 2, wherein the initialization module comprises a third transistor and a fourth transistor;
a gate of the third transistor is connected to the light emitting signal line, a first pole of the third transistor is connected to a first pole of the second transistor, and a second pole of the third transistor is connected to the initialization signal;
the grid electrode of the fourth transistor is connected with the scanning line, the first pole of the fourth transistor is connected with the initialization signal, and the second pole of the fourth transistor is connected with the first pole of the light-emitting device.
4. The pixel circuit according to claim 1, wherein the switching module comprises a fifth transistor, a sixth transistor, a seventh transistor;
a gate of the fifth transistor is connected to the scan line, a first pole of the fifth transistor is connected to the data signal, and a second pole of the fifth transistor is connected to the first pole of the driving transistor;
a gate of the sixth transistor is connected to the light emitting signal line, a first pole of the sixth transistor is connected to the second common voltage terminal, and a second pole of the sixth transistor is connected to the first pole of the driving transistor;
a gate of the seventh transistor is connected to the light emitting signal line, a first pole of the seventh transistor is connected to the second pole of the driving transistor, and a second pole of the seventh transistor is connected to the first pole of the light emitting device.
5. The pixel circuit of claim 1, wherein the first common voltage terminal is a dc low power supply and the second common voltage terminal is a dc high power supply.
6. The pixel circuit according to claim 1, wherein the initialization signal is a dc low power supply.
7. The pixel circuit according to claim 1, wherein the light emitting device is a light emitting diode.
8. The pixel circuit according to claim 7, wherein the light emitting device comprises sub-millimeter light emitting diodes, micro light emitting diodes, and organic light emitting diodes.
9. A pixel circuit, comprising:
a light emitting device, the cathode of which is connected to a common ground voltage terminal;
the upper pole plate of the first storage capacitor is connected to a power supply voltage end;
the upper pole plate of the second storage capacitor is connected to a power supply voltage end;
a grid electrode of the first transistor is connected with a scanning line, a source electrode of the first transistor is connected with a drain electrode of the eighth transistor, and the drain electrode of the first transistor is connected with a lower polar plate of the second storage capacitor;
a gate of the second transistor is connected with the scan line, a source of the second transistor is connected with a lower plate of the first storage capacitor, and a drain of the second transistor is connected with a lower plate of the second storage capacitor;
a third transistor, a gate of which is connected to a light emitting signal line, a source of which is connected to a source of the second transistor, and a drain of which is connected to an initialization voltage terminal;
a fourth transistor, a gate of which is connected to the scan line, a source of which is connected to the initialization voltage terminal, and a drain of which is connected to an anode of the light emitting device;
a gate of the fifth transistor is connected to the scan line, a source of the fifth transistor is connected to the data line, and a drain of the fifth transistor is connected to the source of the eighth transistor;
a sixth transistor, a gate of which is connected to the light emitting signal line, a source of which is connected to a power supply voltage terminal, and a drain of which is connected to a drain of the fifth transistor;
a seventh transistor, a gate of which is connected to the light emitting signal line, a source of which is connected to the source of the first transistor, and a drain of which is connected to an anode of the light emitting device;
and a gate of the eighth transistor is connected to the drain of the first transistor, a source of the eighth transistor is connected to the drain of the fifth transistor, and a drain of the eighth transistor is connected to the source of the seventh transistor.
10. A pixel driving method for driving the pixel circuit according to any one of claims 1 to 8, wherein the pixel driving method comprises:
in a data signal writing stage, a scanning signal loaded by the scanning line enables the switch module, the compensation module and the initialization module to work so as to write the data signal into the grid electrode of the driving transistor and the compensation module, and the compensation module maintains the grid electrode voltage of the driving transistor and compensates the threshold voltage in the driving transistor; the initialization module initializes the light emitting device;
in a light emitting stage, a light emitting signal loaded by the light emitting signal line enables the switch module and the initialization module to work, the compensation module maintains the conduction of the driving transistor to drive the light emitting device to emit light, and the initialization module writes the initialization signal into the compensation module.
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| CN202010304374.8A CN111508420A (en) | 2020-04-17 | 2020-04-17 | Pixel circuit and driving method thereof |
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