CN114708838A - Pixel circuit, driving method thereof and display panel - Google Patents

Pixel circuit, driving method thereof and display panel Download PDF

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Publication number
CN114708838A
CN114708838A CN202210457554.9A CN202210457554A CN114708838A CN 114708838 A CN114708838 A CN 114708838A CN 202210457554 A CN202210457554 A CN 202210457554A CN 114708838 A CN114708838 A CN 114708838A
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Prior art keywords
module
driving
voltage
transistor
terminal
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Chinese (zh)
Inventor
盖翠丽
郭恩卿
李俊峰
邢汝博
郭双
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Yungu Guan Technology Co Ltd
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Yungu Guan Technology Co Ltd
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Priority to CN202210457554.9A priority Critical patent/CN114708838A/en
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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
    • G09G3/3258—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 with pixel circuitry controlling the voltage across the light-emitting element
    • 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]
    • 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]
    • 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]
    • G09G3/3266—Details of drivers for scan electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of El Displays (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The embodiment of the invention discloses a pixel circuit, a driving method thereof and a display panel. Wherein the pixel circuit includes: the device comprises a first compensation module, a data writing module, a storage module, a driving module and a light emitting module; the first compensation module is used for writing the voltage of the first power supply voltage end into the control end of the driving module in an initialization stage and compensating the threshold voltage of the driving module in a compensation stage; the data writing module is used for coupling the data voltage to the control end of the driving module in a data writing stage; one end of the storage module is coupled to the control end of the driving module, the other end of the storage module is connected with the second end of the driving module, and the storage module is used for storing the voltage between the control end and the second end of the driving module. The technical scheme of the embodiment of the invention is beneficial to improving the problems of uneven threshold voltage of the driving module, voltage drop of the second power supply voltage and uneven display caused by aging of the light emitting module, thereby improving the display effect.

Description

Pixel circuit, driving method thereof and display panel
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a pixel circuit, a driving method thereof and a display panel.
Background
With the continuous development of display technology, people have higher and higher performance requirements on display panels. The display panel includes a plurality of pixel circuits including a driving transistor for driving the light emitting device to emit light. Since the driving current generated by the driving transistor is easily affected by factors such as threshold voltage, the display panel has the problem of display non-uniformity, thereby affecting the display effect.
Disclosure of Invention
The embodiment of the invention provides a pixel circuit, a driving method thereof and a display panel, which are used for improving the problem of uneven display and further improving the display effect.
In a first aspect, an embodiment of the present invention provides a pixel circuit, including: the device comprises a first compensation module, a data writing module, a storage module, a driving module and a light emitting module;
the driving module and the light-emitting module are sequentially connected between a first power supply voltage end and a second power supply voltage end, a first end of the first compensation module is connected with a control end of the driving module, a second end of the first compensation module is respectively connected with the first power supply voltage end and the first end of the driving module, and the first compensation module is used for writing the voltage of the first power supply voltage end into the control end of the driving module in an initialization stage and compensating the threshold voltage of the driving module in a compensation stage;
the data writing module is connected with the control end of the driving module and is used for coupling data voltage to the control end of the driving module in a data writing stage;
one end of the storage module is coupled to the control end of the driving module, the other end of the storage module is connected with the second end of the driving module, and the storage module is used for storing the voltage between the control end and the second end of the driving module;
the driving module is used for responding to the voltage between the control end and the second end of the driving module to generate driving current in the light-emitting stage so as to drive the light-emitting module to emit light.
Optionally, the lighting device further includes a first initialization module, a control terminal of the first initialization module is connected to a first scan signal, a first terminal of the first initialization module is connected to a first initialization voltage, a second terminal of the first initialization module is connected to a second terminal of the driving module, and the first initialization module is configured to respond to the first scan signal and write the first initialization voltage into the second terminal of the driving module before a lighting phase;
preferably, the first initialization module includes a first transistor, a gate of the first transistor is connected to the first scan signal, a first pole of the first transistor is connected to the first initialization voltage, and a second pole of the first transistor is connected to the second end of the driving module;
preferably, the first initialization voltage is less than a lighting voltage of the light emitting module.
Optionally, the pixel circuit further includes a light-emitting control module, a first end of the light-emitting control module is connected to the first power voltage terminal, a second end of the light-emitting control module is respectively connected to a second end of the first compensation module and a first end of the driving module, a second end of the first compensation module is connected to the first power voltage terminal through the light-emitting control module, and a control terminal of the light-emitting control module receives a light-emitting control signal;
the light-emitting control module is used for responding to the light-emitting control signal and conducting in an initialization stage, so that the first compensation module writes the voltage of the first power supply voltage end into the control end of the driving module;
preferably, the light emission control module includes a second transistor, the first compensation module includes a third transistor, a gate of the second transistor is connected to the light emission control signal, a first pole of the second transistor is connected to the first power voltage terminal, a second pole of the second transistor is connected to the first terminal of the driving module, a gate of the third transistor is connected to the second scan signal, a first pole of the third transistor is connected to the control terminal of the driving module, and a second pole of the third transistor is connected to the first terminal of the driving module.
Optionally, the data writing module includes a data writing unit and a coupling unit, a control end of the data writing unit is connected to the third scanning signal, a first end of the data writing unit is connected to the data voltage, a second end of the data writing unit is connected to the first end of the coupling unit, and a second end of the coupling unit is connected to the control end of the driving module;
the data writing unit is used for responding to the third scanning signal and writing the data voltage into the first end of the coupling unit in a data writing stage, and the coupling unit is used for coupling the voltage of the second end of the coupling unit according to the voltage change of the first end of the coupling unit;
preferably, the data writing unit includes a fourth transistor, the coupling unit includes a first capacitor, a gate of the fourth transistor is connected to the third scan signal, a first pole of the fourth transistor is connected to the data voltage, a second pole of the fourth transistor is connected to the first pole of the first capacitor, and a second pole of the first capacitor is connected to the control terminal of the driving module;
preferably, the pixel circuit further includes a second initialization module, a control terminal of the second initialization module is connected to a second scan signal, a first terminal of the second initialization module is connected to a second initialization voltage, a second terminal of the second initialization module is connected to the first terminal of the coupling unit, and the second initialization module is configured to write the second initialization voltage to the first terminal of the coupling unit in an initialization stage in response to the second scan signal;
preferably, the second initialization module includes a fifth transistor, a gate of the fifth transistor is connected to the second scan signal, a first pole of the fifth transistor is connected to the second initialization voltage, and a second pole of the fifth transistor is connected to the first end of the coupling unit.
Optionally, the first end of the storage module is connected to the second end of the driving module, and the second end of the storage module is coupled to the control end of the driving module through the data writing module, or the second end of the storage module is connected to the control end of the driving module;
preferably, the memory module comprises a second capacitor.
Optionally, the driving module includes a driving transistor, the driving transistor is a vertical double-gate transistor, the driving transistor includes a first gate and a second gate, and the first gate is used as a control terminal of the driving module;
the pixel circuit further comprises a second compensation module, the second compensation module is connected with the second grid electrode and the second pole of the driving transistor, and the second compensation module is used for fixing the voltage difference between the second grid electrode and the second pole of the driving transistor so as to stabilize the threshold voltage of the driving transistor.
Optionally, the second compensation module includes a switch unit and a storage unit, a control terminal of the switch unit is connected to a first scan signal, a first terminal of the switch unit is connected to a preset voltage signal, a second terminal of the switch unit is connected to the second gate of the driving transistor and the first terminal of the storage unit, and a second terminal of the storage unit is connected to the second pole of the driving transistor;
the switch unit is used for responding to the first scanning signal and conducting before a light-emitting stage so as to write the preset voltage signal into the second grid electrode of the driving transistor and the first end of the storage unit, and the storage unit stores the voltage of the second grid electrode and the second pole of the driving transistor;
the switch unit is also used for responding to the first scanning signal and switching off in a light-emitting stage so that the storage unit couples the voltage of the first end of the storage unit according to the voltage change of the second end of the storage unit in the light-emitting stage;
preferably, the switching unit includes a sixth transistor, the storage unit includes a third capacitor, a gate of the sixth transistor is connected to the first scan signal, a first pole of the sixth transistor is connected to the preset voltage signal, a second pole of the sixth transistor is connected to the first pole of the third capacitor, and a second pole of the third capacitor is connected to the second pole of the driving transistor.
In a second aspect, an embodiment of the present invention further provides a driving method of a pixel circuit, where the pixel circuit includes: the device comprises a first compensation module, a data writing module, a storage module, a driving module and a light emitting module; the driving module and the light-emitting module are sequentially connected between a first power supply voltage end and a second power supply voltage end, a first end of the first compensation module is connected with a control end of the driving module, a second end of the first compensation module is respectively connected with the first power supply voltage end and the first end of the driving module, the data writing module is connected with the control end of the driving module, one end of the storage module is coupled to the control end of the driving module, the other end of the storage module is connected with the second end of the driving module, and the storage module is used for storing voltage between the control end and the second end of the driving module;
the driving method of the pixel circuit includes:
in an initialization stage, writing the voltage of the first power supply voltage end into the control end of the driving module through the first compensation module;
in a compensation stage, compensating the threshold voltage of the driving module through the first compensation module;
in a data writing stage, coupling a data voltage to a control end of the driving module through the data writing module;
and in the light-emitting stage, the driving module responds to the voltage between the control end and the second end of the driving module to generate a driving current so as to drive the light-emitting module to emit light.
Optionally, the driving module includes a driving transistor, the driving transistor is a vertical double-gate transistor, the driving transistor includes a first gate and a second gate, and the first gate is used as a control terminal of the driving module; the pixel circuit further comprises a second compensation module, wherein the second compensation module is connected with the second grid electrode and the second pole of the driving transistor;
the driving method of the pixel circuit further includes:
and fixing the voltage difference between the second grid electrode and the second pole of the driving transistor through the second compensation module so as to stabilize the threshold voltage of the driving transistor.
In a third aspect, an embodiment of the present invention further provides a display panel, including the pixel circuit described in the first aspect.
According to the pixel circuit, the driving method thereof and the display panel provided by the embodiment of the invention, the voltage of the first power supply voltage end is written into the control end of the driving module by controlling the first compensation module in the initialization stage, so that the driving module is conducted, the first compensation module is controlled to compensate the threshold voltage of the driving module in the compensation stage, and the driving current generated by the driving module is unrelated to the threshold voltage of the driving module. The data voltage is coupled to the control end of the driving module in the data writing stage through controlling the data writing module, so that the driving current generated by the driving module is related to the data voltage. One end of the storage module is coupled to the control end of the driving module, and the other end of the storage module is connected with the second end of the driving module, so that the voltage change of the second end of the driving module can be coupled to the control end of the driving module in a light-emitting stage, and the driving current generated by the driving module is unrelated to the second power voltage and the lighting voltage of the light-emitting module. The current generated by the driving module in the light-emitting stage is related to the data voltage and is unrelated to the threshold voltage of the driving module, the second power voltage and the lighting voltage of the light-emitting module, so that the problems of uneven threshold voltage of the driving module, uneven voltage drop of the second power voltage and uneven display caused by aging of the light-emitting module are improved, and the display effect is improved. In addition, threshold voltage compensation and data voltage writing of the driving module are achieved through different paths, so that threshold voltage compensation time is adjustable, compensation for the condition that the fluctuation range of the threshold voltage is large is facilitated, and display uniformity is further improved.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present invention, nor do they necessarily limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a functional block diagram of a pixel circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another pixel circuit according to an embodiment of the invention;
fig. 4 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a driving timing sequence of a pixel circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention;
fig. 9 is a flowchart illustrating a driving method of a pixel circuit according to an embodiment of the invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, 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.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As described in the background art, the conventional display panel has a problem of display unevenness, thereby affecting the display effect. The inventors found that the above problems occur due to the following reasons:
the driving transistor in the pixel circuit has a threshold voltage shifted due to its characteristics, and the like, thereby affecting the driving current generated by the driving transistor. If the threshold voltage of the driving transistors in different pixel circuits are shifted to different levels, display non-uniformity may result. The light emitting device is aged after being used for a long time, which causes problems such as increase of lighting voltage and decrease of light emitting efficiency of the light emitting device. The display panel may have different aging degrees of different light emitting devices, which may also cause uneven display. In addition, the light emitting device needs to be connected with a power supply voltage, a signal line for transmitting the power supply voltage is arranged in the display panel, and due to the fact that a load exists in the signal line, the power supply voltage on the signal line has a voltage Drop (IR-Drop), so that the light emitting devices in different areas in the display panel are connected with different power supply voltages, display unevenness is caused, and the display effect is influenced.
In view of the above problems, embodiments of the present invention provide a pixel circuit. Fig. 1 is a schematic diagram of functional modules of a pixel circuit according to an embodiment of the present invention. Referring to fig. 1, the pixel circuit includes: the device comprises a first compensation module 10, a data writing module 20, a storage module 30, a driving module 40 and a light emitting module 50.
The driving module 40 and the light emitting module 50 are sequentially connected between a first power voltage terminal and a second power voltage terminal, the first power voltage terminal is connected to a first power voltage VDD, and the second power voltage terminal is connected to a second power voltage VSS. The first end of the first compensation module 10 is connected to the control end of the driving module 40, the second end of the first compensation module 10 is connected to the first power voltage end and the first end of the driving module 40, respectively, and the first compensation module 10 is configured to write the voltage of the first power voltage end into the control end of the driving module 40 in the initialization stage, and compensate the threshold voltage of the driving module 40 in the compensation stage.
The data writing module 20 is connected to the control terminal of the driving module 40, and the data writing module 20 is configured to couple the data voltage Vdata to the control terminal of the driving module 40 during a data writing phase.
One end of the memory module 30 is coupled to the control end of the driving module 40, and the other end is connected to the second end of the driving module 40, and the memory module 30 is used for storing the voltage between the control end and the second end of the driving module 40.
The driving module 40 is configured to generate a driving current in response to a voltage between the control terminal and the second terminal during the light emitting period to drive the light emitting module 50 to emit light.
Specifically, in the initialization phase, the first compensation module 10 is controlled to be turned on, so that the first power voltage VDD is written into the control terminal of the driving module 40 through the first compensation module 10, and the driving module 40 can be turned on by the first power voltage VDD.
In the compensation phase, the first compensation module 10 is controlled to connect the control end and the first end of the driving module 40, so as to generate a current path from the point G, the point D to the point S, so that the driving module 40 is continuously turned on, and the driving module 40 is turned off until the voltage difference between the point G and the point S is the threshold voltage Vth of the driving module 40. Taking the initial voltage at the point S as V0 as an example, the driving module 40 is turned off when the voltage at the point G reaches V0+ Vth. The storage module 30 can store a voltage between the control terminal and the second terminal of the driving module 40, i.e., store a voltage between the G point and the S point.
In the data writing phase, the data writing module 20 is controlled to be turned on to couple the data voltage Vdata to the control terminal of the driving module 40 through the data writing module 20, so that the voltage at the point G is related to the data voltage Vdata. The voltage at point G may be represented as V0+ Vth +. DELTA.Vdata, where DELTA.Vdata represents the voltage at which data write module 20 is coupled to the control terminal of drive module 40, i.e., the voltage related to data voltage Vdata. The memory module 30 can store the voltage between the G point and the S point.
In the light emitting stage, the first compensation module 10 is controlled to write the first power voltage VDD into the first terminal of the driving module 40, write the second power voltage VSS into the second terminal of the light emitting module, and the driving module 40 generates a driving current in response to a voltage between the control terminal and the second terminal thereof, that is, generates a driving current in response to a voltage difference between the G point and the S point, so as to drive the light emitting module 50 to emit light. In the light emitting period, the voltage at the point S is raised from V0 to VSS + Voled, where Voled is the turn-on voltage of the light emitting module 50. Since one end of the memory module 30 is coupled to the control end of the driving module 40, and the other end is connected to the second end of the driving module 40, the memory module 30 can couple the voltage variation at the point S to the point G, so that the voltage at the point G becomes V0+ Vth +. DELTA.Vdata + VSS + Voled-V0. Then, in the light emitting phase, the driving current I generated by the driving module 40 can be expressed as: i ℃ (VGS-Vth)2Where VGS represents the differential pressure between the control end and the second end of the drive module 40, i.e., the differential pressure between points G and S.
VGS-Vth＝V0+Vth+△Vdata+VSS+Voled-V0-VSS-Voled-Vth＝△Vdata；
Thus, I. varies (. DELTA.Vdata)2. Since Δ Vdata is a voltage related to the data voltage Vdata, it can be seen that the driving current I generated by the driving module 40 is ultimately related to the data voltage Vdata, regardless of the threshold voltage Vth of the driving module 40, the second power voltage VSS, and the lighting voltage Voled of the light emitting module 50. The brightness of each light emitting module 50 in the display panel is related to the corresponding data voltage VdataThe threshold voltage deviation degree of the driving module 40, the voltage drop of the second power voltage VSS, and the variation of the lighting voltage Voled caused by the aging of the light emitting module 50 are not related, so that the problems of the non-uniform threshold voltage of the driving module 40, the voltage drop of the second power voltage VSS, and the non-uniform display caused by the aging of the light emitting module 50 can be improved.
According to the technical scheme of the embodiment of the invention, the voltage of the first power supply voltage end is written into the control end of the driving module by controlling the first compensation module in the initialization stage, so that the driving module is conducted, the first compensation module is controlled to compensate the threshold voltage of the driving module in the compensation stage, and the driving current generated by the driving module is irrelevant to the threshold voltage of the driving module. The data voltage is coupled to the control end of the driving module in the data writing stage through controlling the data writing module, so that the driving current generated by the driving module is related to the data voltage. One end of the storage module is coupled to the control end of the driving module, and the other end of the storage module is connected with the second end of the driving module, so that the voltage change of the second end of the driving module can be coupled to the control end of the driving module in a light-emitting stage, and the driving current generated by the driving module is unrelated to the second power voltage and the lighting voltage of the light-emitting module. The current generated by the driving module in the light-emitting stage is related to the data voltage and is unrelated to the threshold voltage of the driving module, the second power voltage and the lighting voltage of the light-emitting module, so that the problems of uneven threshold voltage of the driving module, uneven voltage drop of the second power voltage and uneven display caused by aging of the light-emitting module are improved, and the display effect is improved. In addition, threshold voltage compensation and data voltage writing of the driving module are achieved through different paths, so that threshold voltage compensation time is adjustable, compensation for the condition that the fluctuation range of the threshold voltage is large is facilitated, and display uniformity is further improved.
With continued reference to fig. 1, on the basis of the above embodiment, optionally, the pixel circuit further comprises a first initialization module 60. The control terminal of the first initialization module 60 is connected to the first scan signal S1, the first terminal of the first initialization module 60 is connected to the first initialization voltage Vref, and the second terminal of the first initialization module 60 is connected to the second terminal of the driving module 40. The first initialization module 60 is configured to write the first initialization voltage Vref to the second terminal of the driving module 40 before the light emitting period in response to the first scan signal S1.
The first initialization voltage Vref is less than the lighting voltage Voled of the light emitting module 50. The lighting phase is preceded by an initialization phase, a compensation phase and a data writing phase. By controlling the first initialization module 60 to respond to the first scan signal S1 and writing the first initialization voltage Vref to the second terminal of the driving module 40 before the light emitting period, the light emitting module 50 can be prevented from emitting light before the light emitting period, so that the problem that the display panel is not dark enough in the black state is avoided, and the display contrast is improved. Exemplarily, in the initialization phase and the compensation phase, since the driving module 40 is turned on, the driving module 40 can be prevented from driving the light emitting module 50 to emit light in the initialization phase and the compensation phase by writing the first initialization voltage Vref to the second terminal of the driving module 40 before the light emitting phase by the first initialization module 60.
In addition, in the initialization stage, the first initialization voltage Vref is written to the second terminal of the driving module 40 by the first initialization module 60, so that the voltage at the point S is Vref, and the voltage initialization for the first terminal of the light emitting module 50 is realized. In this way, in the compensation phase, the first compensation module 10 is controlled to connect the control terminal and the first terminal of the driving module 40, so as to generate a current path from the point G and the point D to the point S, the driving module 40 is continuously turned on, and the driving module 40 is turned off until the voltage difference between the point G and the point S is the threshold voltage Vth of the driving module 40. When the driving module 40 is turned off, the voltage at the point S is still Vref, and the voltage at the point G is Vref + Vth, so that the first initialization voltage Vref is written into the point G while the threshold voltage compensation of the driving module 40 is realized, and the initialization of the control terminal voltage of the driving module 40 is realized. Therefore, the first initialization module 60 is configured to initialize the voltage of the first terminal of the light emitting module 50 and the voltage of the control terminal of the driving module 40, so that a transistor for initializing the voltage of the control terminal of the driving module 40 does not need to be additionally disposed in the pixel circuit, which helps to reduce the number of transistors in the pixel circuit and improve the aperture ratio of the display panel.
Fig. 2 is a schematic structural diagram of another pixel circuit according to an embodiment of the invention. Referring to fig. 2, the pixel circuit optionally further includes a light emission control module 110. The first end of the light emitting control module 110 is connected to the first power voltage end, the second end of the light emitting control module 110 is connected to the second end of the first compensation module 10 and the first end of the driving module 40, the second end of the first compensation module 10 is connected to the first power voltage end through the light emitting control module 110, and the control end of the light emitting control module 110 receives the light emitting control signal EM. The light emitting control module 110 is configured to be turned on in response to the light emitting control signal EM in an initialization phase, so that the first compensation module 10 writes the voltage of the first power voltage terminal into the control terminal of the driving module 40.
In the initialization phase, by controlling the light emission control module 110 to be turned on in response to the light emission control signal EM and controlling the first compensation module 10 to be turned on in response to the second scan signal S2, the first power voltage VDD can be written into the control terminal of the driving module 40 sequentially through the light emission control module 110 and the first compensation module 10, so that the driving module 40 is turned on. In the compensation phase, the light emission control module 110 is controlled to respond to the light emission control signal EM to be turned off, the first compensation module 10 is turned on in response to the second scan signal S2, a current path from the first compensation module 10, the driving module 40, and the first initialization module 60 to the first initialization signal terminal can be generated, and the driving module 40 is continuously turned on until the voltage difference between the point G and the point S is the threshold voltage Vth of the driving module 40, and the driving module 40 is turned off. When the driving module 40 is turned off, the voltage at the point S is still Vref, and the voltage at the point G is Vref + Vth, so that the threshold voltage compensation of the driving module 40 is realized.
With continued reference to fig. 2, optionally, the data writing module includes a data writing unit 210 and a coupling unit 220. The control terminal of the data writing unit 210 is connected to the third scan signal S3, the first terminal of the data writing unit 210 is connected to the data voltage Vdata, the second terminal of the data writing unit 210 is connected to the first terminal of the coupling unit 220, and the second terminal of the coupling unit 220 is connected to the control terminal of the driving module 40.
In the data writing phase, the data writing unit 210 is controlled to write the data voltage Vdata into the first end of the coupling unit 220 in response to the third scan signal S3, and if the voltage at the point N is Vdata, the coupling unit 220 may couple the voltage at the second end of the coupling unit according to the voltage change at the first end of the coupling unit, that is, couple the voltage at the point G according to the voltage change at the point N, so that the voltage at the point G can be related to the data voltage Vdata, that is, the voltage at the control end of the driving module 40 is related to the data voltage Vdata, and the data voltage writing to the control end of the driving module 40 is implemented.
With continued reference to fig. 2, based on the above embodiment, the pixel circuit optionally further includes a second initialization module 70. The control terminal of the second initializing module 70 is connected to the second scan signal S2, the first terminal of the second initializing module 70 is connected to the second initializing voltage Vint, and the second terminal of the second initializing module 70 is connected to the first terminal of the coupling unit 220. The second initializing module 70 may write a second initializing voltage Vint to the first terminal of the coupling unit 220 in the initializing stage in response to the second scan signal S2, so as to initialize the voltage of the first terminal of the coupling unit 220.
With continued reference to fig. 2, optionally, in one embodiment, a first end of the memory module 30 is configured to be connected to a second end of the driving module 40, and the second end of the memory module 30 is coupled to the control end of the driving module 40 through the data writing module. For example, the second terminal of the memory module 30 may be connected to the first terminal of the coupling unit 220, so that the memory module 30 is coupled to the control terminal of the driving module 40 through the coupling unit 220.
Fig. 3 is a schematic structural diagram of another pixel circuit according to an embodiment of the invention. Referring to fig. 3, in another embodiment, a first end of the memory module 30 is connected to a second end of the driving module 40, and the second end of the memory module 30 is directly connected to a control end of the driving module 40. When the coupling unit 220 and the storage module 30 both include capacitors, the control terminal and the second terminal of the driving module 40 in fig. 2, that is, the capacitance between the point G and the point S is the capacitance of the coupling unit 220 and the storage module 30 connected in series, and the capacitance between the point G and the point S in fig. 3 is the capacitance of the storage module 30, and under the condition that the capacitances between the point G and the point S are the same, the second terminal of the storage module 30 is directly connected to the control terminal of the driving module 40, so that the capacitance of the storage module 30 can be smaller, thereby saving the layout area of the pixel circuit occupied by the capacitors in the storage module 30, which is helpful for saving cost, and also helpful for reducing the area occupied by the pixel circuit in the display panel.
Fig. 4 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention. Referring to fig. 4, on the basis of the above embodiments, optionally, the driving module 40 includes the driving transistor DT, and the light emitting module 50 includes the light emitting device D1.
The first initialization module 60 includes a first transistor T1, a gate of the first transistor T1 is connected to the first scan signal S1, a first pole of the first transistor T1 is connected to the first initialization voltage Vref, and a second pole of the first transistor T1 is connected to the second terminal of the driving module 40 and the first terminal of the light emitting module 50, that is, the second pole of the driving transistor DT and the first pole of the light emitting device D1.
The light emission control module 110 includes a second transistor T2, and the first compensation module 10 includes a third transistor T3. The gate of the second transistor T2 is connected to the emission control signal EM, the first pole of the second transistor T2 is connected to the first power voltage VDD, and the second pole of the second transistor T2 is connected to the first terminal of the driving module 40, i.e., the first pole of the driving transistor DT. The gate of the third transistor T3 is connected to the second scan signal S2, the first pole of the third transistor T3 is connected to the control terminal of the driving module 40, i.e., the gate of the driving transistor DT, and the second pole of the third transistor T3 is connected to the first terminal of the driving module 40, i.e., the first pole of the driving transistor DT.
The data writing unit 210 includes a fourth transistor T4, and the coupling unit 220 includes a first capacitor C1. A gate of the fourth transistor T4 is connected to the third scan signal S3, a first pole of the fourth transistor T4 is connected to the data voltage Vdata, a second pole of the fourth transistor T4 is connected to the first pole of the first capacitor C1, and a second pole of the first capacitor C1 is connected to the control terminal of the driving module 40, i.e., the gate of the driving transistor DT.
The second initialization block 70 includes a fifth transistor T5, a gate of the fifth transistor T5 is connected to the second scan signal S2, a first pole of the fifth transistor T5 is connected to the second initialization voltage Vint, and a second pole of the fifth transistor T5 is connected to the first terminal of the coupling unit 220, i.e., the first pole of the first capacitor C1.
The memory module 30 includes a second capacitor C2, a first pole of the second capacitor C2 is connected to the second terminal of the driving module 40, i.e., the second pole of the driving transistor DT, and a second pole of the second capacitor C2 is coupled to the control terminal of the driving module 40, e.g., the second pole of the second capacitor C2 is connected to the first pole of the first capacitor C1, so that the second capacitor C2 is coupled to the gate of the driving transistor DT through the first capacitor C1.
Fig. 5 is a schematic diagram of a driving timing sequence of a pixel circuit according to an embodiment of the invention. The driving sequence shown in fig. 5 is suitable for driving the pixel circuits shown in fig. 1 to 4 to operate. The operation principle of the pixel circuit provided by the embodiment of the present invention is described below with reference to fig. 4 and 5. Fig. 4 schematically illustrates a case where all transistors in the pixel circuit are N-type transistors, and in practical applications, each transistor in the pixel circuit may be a P-type transistor or an N-type transistor as required, which is not limited in this embodiment. When each transistor in the pixel circuit is an N-type transistor, a signal for controlling each transistor to be turned on is a high-level signal, and a signal for controlling each transistor to be turned off is a low-level signal.
Exemplarily, in the initialization phase t1, the light emission control signal EM, the first scan signal S1, and the second scan signal S2 are high level signals, and the third scan signal S3 is a low level signal. The first transistor T1, the second transistor T2, the third transistor T3, and the fifth transistor T5 are turned on, and the fourth transistor T4 is turned off. The first initialization voltage Vref is written to the point S by the first transistor T1, and the voltage at the point S is set to Vref, so that the first electrode of the light emitting device D1 is initialized. The second initialization voltage Vint is written to point N through the fifth transistor T5, and the voltage at point N is Vint, so as to initialize the first pole of the first capacitor C1. The first power voltage VDD is written to the G point through the second transistor T2 and the third transistor T3, so that the voltage of the G point is VDD. The first power voltage VDD is a high voltage, the first initialization voltage Vref is a low voltage less than the turn-on voltage Voled of the light emitting device D1, a voltage difference between the gate and the second pole of the driving transistor DT is greater than the threshold voltage Vth of the driving transistor DT, the driving transistor DT is turned on, and the light emitting device D1 does not emit light.
In the compensation period t2, the emission control signal EM becomes a low level signal, and the levels of the other signals coincide with the previous period. The second transistor T2 is turned off and the other transistors are in the same state as in the previous stage. The third transistor T3, the driving transistor DT, and the first transistor T1 form a current path to the first initialization voltage terminal, and the driving transistor DT is continuously turned on until a voltage difference between the G point and the S point is equal to a threshold voltage Vth of the driving transistor DT. When the driving transistor DT is turned off, the voltage at the point S is still Vref, the light emitting device D1 does not emit light, and the voltage at the point G becomes Vref + Vth, so that the threshold voltage compensation of the driving module 40 and the gate voltage initialization of the driving transistor DT are realized. The voltage at point N remains unchanged.
In the data writing period t3, the light emission control signal EM and the second scan signal S2 are low level signals, and the first scan signal S1 and the third scan signal S3 are high level signals. The first transistor T1 and the fourth transistor T4 are turned on, and the other transistors are turned off. The data voltage Vdata is written to the N point through the fourth transistor T4, and the voltage of the N point is changed from Vint to Vdata. Due to the coupling effect of the first capacitor C1, the voltage at point G can be coupled to Vref + Vth + Vdata-Vint. The voltage at the point S is still Vref, and the light emitting device D1 does not emit light.
In the light emission period t4, the light emission control signal EM changes to a high level signal, and the other signals are all low level signals. The second transistor T2 and the driving transistor DT are turned on, and the other transistors are turned off. The first power voltage VDD is written to the first pole of the driving transistor DT, the second power voltage VSS is written to the second pole of the light emitting device D1, and the driving transistor DT generates a driving current to drive the light emitting device D1 to emit light. The voltage at the point S is raised to VSS + Voled from Vref, and the voltage at the point G can be coupled to Vref + Vth + Vdata-Vint + VSS + Voled-Vref due to the coupling effect of the first capacitor C1 and the second capacitor C2. The driving transistor DT operates in a saturation region, and the driving current I generated by the driving transistor DT can be expressed as:
I＝K*(VGS-Vth)2
＝K*(Vref+Vth+Vdata-Vint+VSS+Voled-Vref-VSS-Voled-Vth)2
＝K*(Vdata-Vint)2
where K is 1/2 μ Cox W/L, μ is the mobility of the driving transistor DT, Cox is the gate insulating layer capacitance, W/L is the channel width-to-length ratio of the driving transistor DT, and VGS indicates the gate-source voltage difference of the driving transistor DT.
It can be seen that the driving current I is not related to the threshold voltage of the driving transistor DT, the second power voltage VSS, and the turn-on voltage Voled of the light emitting device D1, that is, the pixel circuit can compensate for the non-uniformity of the threshold voltage of the driving transistor DT, the voltage drop of the second power voltage VSS, and the non-uniformity of the display caused by the aging of the light emitting device D1, thereby improving the display effect.
Fig. 6 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention. The driving sequence shown in fig. 5 is also applicable to driving the pixel circuit to operate, and the specific principle can be understood with reference to the above embodiments, which are not described herein again. The pixel circuit is different from the pixel circuit shown in fig. 4 only in that the second pole of the second capacitor C2 is directly connected to the gate of the driving transistor DT. During the light emitting period, when the voltage at the point S rises, the second capacitor C2 can couple the voltage change at the point S to the point G, so that the voltage rises at the point S and the point G are equal. In fig. 4, the capacitance between the gate and the second pole of the driving transistor DT, that is, the G point and the S point, is the capacitance of the first capacitor C1 and the second capacitor C2 connected in series, the capacitance between the G point and the S point in this embodiment is the capacitance of the second capacitor C2, and under the condition that the capacitances between the G point and the S point are the same, the capacitance of the second capacitor C2 in this embodiment may be smaller, so that the layout area of the pixel circuit occupied by the second capacitor C2 is saved, which not only helps to save cost, but also helps to reduce the area occupied by the pixel circuit in the display panel.
Fig. 7 is a schematic structural diagram of another pixel circuit according to an embodiment of the disclosure. Referring to fig. 7, optionally, in another embodiment, the driving transistor DT may also be a vertical double-gate transistor, and the driving transistor DT includes a first gate and a second gate, and the first gate is used as a control terminal of the driving module 40. Correspondingly, the pixel circuit further includes a second compensation module 80, the second compensation module 80 is connected to the second gate and the second pole of the driving transistor DT, and the second compensation module 80 is configured to fix a voltage difference between the second gate and the second pole of the driving transistor DT to stabilize the threshold voltage of the driving transistor DT.
Wherein the first gate may be a top gate and the second gate may be a bottom gate. It is known from the characteristics of the vertical double-gate transistor that the threshold voltage of the driving transistor DT is affected by the voltage difference between the second gate and the second pole, and the larger the voltage difference between the second gate and the second pole, the more negative the threshold voltage of the driving transistor DT, and the smaller the voltage difference between the second gate and the second pole, the more positive the threshold voltage of the driving transistor DT, and when the voltage difference between the second gate and the second pole is maintained, the threshold voltage of the driving transistor DT is maintained.
Before the light emitting period, the threshold voltage of the driving transistor DT can be maintained constant by controlling the second compensation module 80 to fix the voltage difference between the second gate and the second pole of the driving transistor DT. In the light emitting stage, the voltage at the point S rises, and the second compensation module 80 is controlled to fix the voltage difference between the second gate and the second pole of the driving transistor DT, that is, fix the voltage difference between the point B and the point S, so that it can be avoided that the threshold voltage of the driving transistor DT changes in the light emitting stage due to the change of the voltage difference between the second gate and the second pole of the driving transistor DT, and the threshold voltage of the driving transistor DT cannot be sufficiently compensated, which is helpful for making the threshold voltage compensation of the driving transistor DT more sufficient and accurate.
With continued reference to fig. 7, on the basis of the above-described embodiment, optionally, the second compensation module 80 includes a switch unit 810 and a storage unit 820. The control terminal of the switching unit 810 is connected to the first scan signal S1, the first terminal of the switching unit 810 is connected to the preset voltage signal VBG, the second terminal of the switching unit 810 is connected to the second gate of the driving transistor DT and the first terminal of the memory unit 820, and the second terminal of the memory unit 820 is connected to the second pole of the driving transistor DT. The preset voltage signal VBG is a fixed voltage signal, and a specific voltage value of the preset voltage signal VBG can be set according to requirements.
Before the light emitting period, the control switch unit 810 is turned on in response to the first scan signal S1 to write a preset voltage signal VBG into the second gate of the driving transistor DT and the first terminal of the memory unit 820, the voltage at the point B is VBG, the voltage at the point S is Vref, and the memory unit 820 may store the voltages of the second gate and the second pole of the driving transistor DT, that is, the voltages at the points B and S, to fix the voltage difference between the second gate and the second pole of the driving transistor DT, so that the threshold voltage of the driving transistor DT is maintained constant.
In the light emitting stage, the control switch unit 810 is turned off in response to the first scan signal S1, and the point B floats, so that the memory unit 820 couples the voltage of the first terminal thereof according to the voltage variation of the second terminal thereof. In the light emitting phase, the voltage at the point S rises, and the memory unit 820 has a coupling effect, so that the point B can generate the same voltage change, and thus the voltage difference between the point B and the point S, that is, the voltage difference between the second gate and the second pole of the driving transistor DT is fixed, and the threshold voltage of the driving transistor DT is kept unchanged, so that the threshold voltage of the driving transistor DT is prevented from changing in the light emitting phase, and thus the threshold voltage of the driving transistor DT cannot be fully compensated, which is beneficial to making the threshold voltage compensation of the driving transistor DT more fully accurate.
Fig. 8 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention. Referring to fig. 8, on the basis of the above embodiment, optionally, the switch unit 810 includes a sixth transistor T6, and the memory unit 820 includes a third capacitor C3. A gate of the sixth transistor T6 is connected to the first scan signal S1, a first pole of the sixth transistor T6 is connected to the preset voltage signal VBG, a second pole of the sixth transistor T6 is connected to the first pole of the third capacitor C3, and a second pole of the third capacitor C3 is connected to the second pole of the driving transistor DT.
The driving sequence shown in fig. 5 is also applicable to driving the pixel circuit in fig. 8 to operate. Referring to fig. 5 and 8, for example, in the initialization period T1, the compensation period T2 and the data writing period T3, the first scan signal S1 is a high level signal, and the sixth transistor T6 is turned on. The predetermined voltage VBG is written into the point B through the sixth transistor T6, the voltage at the point S is Vref, and the third capacitor C3 stores the voltages at the points B and S to fix the voltage difference between the second gate and the second pole of the driving transistor DT, so that the threshold voltage of the driving transistor DT is maintained constant.
In the light emitting period T4, the first scan signal S1 is a low level signal, and the sixth transistor T6 is turned off. Because the third capacitor C3 has a coupling effect, in the light emitting phase, as the voltage at the point S rises, the third capacitor C3 can couple the voltage at the point B, so that the point B changes with the same voltage, thereby fixing the voltage difference between the point B and the point S, i.e. fixing the voltage difference between the second gate and the second pole of the driving transistor DT, and maintaining the threshold voltage of the driving transistor DT unchanged, so as to avoid the threshold voltage of the driving transistor DT from changing in the light emitting phase, thereby causing the threshold voltage of the driving transistor DT not to be fully compensated, and facilitating the threshold voltage compensation of the driving transistor DT to be more fully and accurately.
Embodiments of the present invention further provide a display panel, which may be a Light-Emitting Diode (LED) display panel, an Organic Light-Emitting Diode (OLED) display panel, an Active-Matrix Organic Light-Emitting Diode (AMOLED) display panel, a Micro LED display panel, and the like. The display panel provided by the embodiment of the invention comprises the pixel circuit in any embodiment, so that the display panel has the structure in the pixel circuit and the corresponding beneficial effects, and the description is omitted.
The embodiment of the invention further provides a driving method of the pixel circuit, and fig. 9 is a flow diagram of the driving method of the pixel circuit provided by the embodiment of the invention. The driving method of the pixel circuit provided by the embodiment of the invention is suitable for driving the pixel circuit in any embodiment to work. Referring to fig. 9, the method specifically includes the following steps:
and S110, writing the voltage of the first power supply voltage end into the control end of the driving module through the first compensation module in an initialization stage.
And S120, in the compensation stage, compensating the threshold voltage of the driving module through the first compensation module.
And S130, coupling the data voltage to the control end of the driving module through the data writing module in the data writing stage.
And S140, in the light emitting stage, the driving module responds to the voltage between the control end and the second end of the driving module to generate driving current so as to drive the light emitting module to emit light.
According to the technical scheme of the embodiment of the invention, the voltage of the first power supply voltage end is written into the control end of the driving module by controlling the first compensation module in the initialization stage, so that the driving module is conducted, the first compensation module is controlled to compensate the threshold voltage of the driving module in the compensation stage, and the driving current generated by the driving module is irrelevant to the threshold voltage of the driving module. The data voltage is coupled to the control end of the driving module in the data writing stage through controlling the data writing module, so that the driving current generated by the driving module is related to the data voltage. One end of the storage module is coupled to the control end of the driving module, and the other end of the storage module is connected with the second end of the driving module, so that the voltage change of the second end of the driving module can be coupled to the control end of the driving module in a light-emitting stage, and the driving current generated by the driving module is unrelated to the second power voltage and the lighting voltage of the light-emitting module. The current generated by the driving module in the light-emitting stage is related to the data voltage and is unrelated to the threshold voltage of the driving module, the second power voltage and the lighting voltage of the light-emitting module, so that the problems of uneven threshold voltage of the driving module, uneven voltage drop of the second power voltage and uneven display caused by aging of the light-emitting module are improved, and the display effect is improved. In addition, threshold voltage compensation and data voltage writing of the driving module are achieved through different paths, so that threshold voltage compensation time is adjustable, compensation for the condition that the fluctuation range of the threshold voltage is large is facilitated, and display uniformity is further improved.
On the basis of the foregoing embodiment, optionally, the driving method of the pixel circuit further includes: and fixing the voltage difference between the second grid electrode and the second pole of the driving transistor through the second compensation module so as to stabilize the threshold voltage of the driving transistor.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A pixel circuit, comprising: the device comprises a first compensation module, a data writing module, a storage module, a driving module and a light emitting module;
the driving module and the light-emitting module are sequentially connected between a first power supply voltage end and a second power supply voltage end, a first end of the first compensation module is connected with a control end of the driving module, a second end of the first compensation module is respectively connected with the first power supply voltage end and the first end of the driving module, and the first compensation module is used for writing the voltage of the first power supply voltage end into the control end of the driving module in an initialization stage and compensating the threshold voltage of the driving module in a compensation stage;
the data writing module is connected with the control end of the driving module and is used for coupling data voltage to the control end of the driving module in a data writing stage;
one end of the storage module is coupled to the control end of the driving module, the other end of the storage module is connected with the second end of the driving module, and the storage module is used for storing the voltage between the control end and the second end of the driving module;
the driving module is used for responding to the voltage between the control end and the second end of the driving module to generate driving current in the light-emitting stage so as to drive the light-emitting module to emit light.
2. The pixel circuit according to claim 1, further comprising a first initialization module, wherein a control terminal of the first initialization module is connected to a first scan signal, a first terminal of the first initialization module is connected to a first initialization voltage, a second terminal of the first initialization module is connected to a second terminal of the driving module, and the first initialization module is configured to write the first initialization voltage to the second terminal of the driving module before a light emitting period in response to the first scan signal;
preferably, the first initialization module includes a first transistor, a gate of the first transistor is connected to the first scan signal, a first pole of the first transistor is connected to the first initialization voltage, and a second pole of the first transistor is connected to the second end of the driving module;
preferably, the first initialization voltage is less than a lighting voltage of the light emitting module.
3. The pixel circuit according to claim 1, further comprising a light emission control module, wherein a first end of the light emission control module is connected to the first power voltage terminal, a second end of the light emission control module is respectively connected to a second end of the first compensation module and a first end of the driving module, a second end of the first compensation module is connected to the first power voltage terminal through the light emission control module, and a control terminal of the light emission control module receives a light emission control signal;
the light-emitting control module is used for responding to the light-emitting control signal and conducting in an initialization stage so that the first compensation module writes the voltage of the first power supply voltage end into the control end of the driving module;
preferably, the light emission control module includes a second transistor, the first compensation module includes a third transistor, a gate of the second transistor is connected to the light emission control signal, a first pole of the second transistor is connected to the first power voltage terminal, a second pole of the second transistor is connected to the first terminal of the driving module, a gate of the third transistor is connected to the second scan signal, a first pole of the third transistor is connected to the control terminal of the driving module, and a second pole of the third transistor is connected to the first terminal of the driving module.
4. The pixel circuit according to claim 1, wherein the data writing module includes a data writing unit and a coupling unit, a control terminal of the data writing unit is connected to a third scanning signal, a first terminal of the data writing unit is connected to the data voltage, a second terminal of the data writing unit is connected to the first terminal of the coupling unit, and a second terminal of the coupling unit is connected to the control terminal of the driving module;
the data writing unit is used for responding to the third scanning signal and writing the data voltage into the first end of the coupling unit in a data writing stage, and the coupling unit is used for coupling the voltage of the second end of the coupling unit according to the voltage change of the first end of the coupling unit;
preferably, the data writing unit includes a fourth transistor, the coupling unit includes a first capacitor, a gate of the fourth transistor is connected to the third scan signal, a first pole of the fourth transistor is connected to the data voltage, a second pole of the fourth transistor is connected to the first pole of the first capacitor, and a second pole of the first capacitor is connected to the control terminal of the driving module;
preferably, the pixel circuit further includes a second initialization module, a control terminal of the second initialization module is connected to a second scan signal, a first terminal of the second initialization module is connected to a second initialization voltage, a second terminal of the second initialization module is connected to the first terminal of the coupling unit, and the second initialization module is configured to write the second initialization voltage to the first terminal of the coupling unit in an initialization stage in response to the second scan signal;
preferably, the second initialization module includes a fifth transistor, a gate of the fifth transistor is connected to the second scan signal, a first pole of the fifth transistor is connected to the second initialization voltage, and a second pole of the fifth transistor is connected to the first end of the coupling unit.
5. The pixel circuit according to claim 1, wherein the first terminal of the memory module is connected to the second terminal of the driving module, and the second terminal of the memory module is coupled to the control terminal of the driving module through the data writing module, or the second terminal of the memory module is connected to the control terminal of the driving module;
preferably, the memory module comprises a second capacitor.
6. The pixel circuit according to claim 1, wherein the driving module comprises a driving transistor, the driving transistor is a vertical double-gate transistor, the driving transistor comprises a first gate and a second gate, and the first gate is used as a control terminal of the driving module;
the pixel circuit further comprises a second compensation module, the second compensation module is connected with the second grid electrode and the second pole of the driving transistor, and the second compensation module is used for fixing the voltage difference between the second grid electrode and the second pole of the driving transistor so as to stabilize the threshold voltage of the driving transistor.
7. The pixel circuit according to claim 6, wherein the second compensation module comprises a switch unit and a memory unit, a control terminal of the switch unit is connected to a first scan signal, a first terminal of the switch unit is connected to a preset voltage signal, a second terminal of the switch unit is connected to the second gate of the driving transistor and the first terminal of the memory unit, and a second terminal of the memory unit is connected to the second pole of the driving transistor;
the switch unit is used for responding to the first scanning signal and conducting before a light-emitting stage so as to write the preset voltage signal into the second grid electrode of the driving transistor and the first end of the storage unit, and the storage unit stores the voltage of the second grid electrode and the second pole of the driving transistor;
the switch unit is also used for responding to the first scanning signal and switching off in a light-emitting stage so that the storage unit couples the voltage of the first end of the storage unit according to the voltage change of the second end of the storage unit in the light-emitting stage;
preferably, the switching unit includes a sixth transistor, the storage unit includes a third capacitor, a gate of the sixth transistor is connected to the first scan signal, a first pole of the sixth transistor is connected to the preset voltage signal, a second pole of the sixth transistor is connected to the first pole of the third capacitor, and a second pole of the third capacitor is connected to the second pole of the driving transistor.
8. A driving method of a pixel circuit, the pixel circuit comprising: the device comprises a first compensation module, a data writing module, a storage module, a driving module and a light emitting module; the driving module and the light-emitting module are sequentially connected between a first power supply voltage end and a second power supply voltage end, a first end of the first compensation module is connected with a control end of the driving module, a second end of the first compensation module is respectively connected with the first power supply voltage end and the first end of the driving module, the data writing module is connected with the control end of the driving module, one end of the storage module is coupled to the control end of the driving module, the other end of the storage module is connected with the second end of the driving module, and the storage module is used for storing voltage between the control end and the second end of the driving module;
the driving method of the pixel circuit includes:
in an initialization stage, writing the voltage of the first power supply voltage end into the control end of the driving module through the first compensation module;
in a compensation stage, compensating the threshold voltage of the driving module through the first compensation module;
in a data writing stage, coupling a data voltage to a control end of the driving module through the data writing module;
and in the light-emitting stage, the driving module responds to the voltage between the control end and the second end of the driving module to generate a driving current so as to drive the light-emitting module to emit light.
9. The driving method of the pixel circuit according to claim 8, wherein the driving module comprises a driving transistor, the driving transistor is a vertical double-gate transistor, the driving transistor comprises a first gate and a second gate, and the first gate is used as a control terminal of the driving module; the pixel circuit further comprises a second compensation module, wherein the second compensation module is connected with the second grid electrode and the second pole of the driving transistor;
the driving method of the pixel circuit further includes:
and fixing the voltage difference between the second grid electrode and the second pole of the driving transistor through the second compensation module so as to stabilize the threshold voltage of the driving transistor.
10. A display panel comprising the pixel circuit according to any one of claims 1 to 7.
CN202210457554.9A 2022-04-27 2022-04-27 Pixel circuit, driving method thereof and display panel Pending CN114708838A (en)

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