CN111354314A - Pixel circuit, driving method of pixel circuit and display panel - Google Patents
Pixel circuit, driving method of pixel circuit and display panel Download PDFInfo
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- CN111354314A CN111354314A CN202010183703.8A CN202010183703A CN111354314A CN 111354314 A CN111354314 A CN 111354314A CN 202010183703 A CN202010183703 A CN 202010183703A CN 111354314 A CN111354314 A CN 111354314A
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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
- G09G3/3233—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 current through the light-emitting element
Abstract
The invention discloses a pixel circuit and a display panel. The pixel circuit includes a driving transistor for supplying a driving current to the light emitting device in a light emitting stage, the light emitting device emitting light in response to the driving current; the first initialization module is connected between the grid of the driving transistor and a first initialization power supply end and used for supplying the voltage of the first initialization power supply end to the grid of the driving transistor in a first initialization stage; a second initialization module connected between the gate of the driving transistor and a second initialization power supply terminal, for supplying the voltage of the second initialization power supply terminal to the gate of the driving transistor before the first initialization stage; the voltage of the first initialization power supply terminal is smaller than the voltage of the second initialization power supply terminal. The invention can weaken the hysteresis effect of the driving transistor, further improve the afterimage phenomenon of the display panel where the pixel circuit is positioned, and improve the display effect of the display panel.
Description
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a pixel circuit, a driving method of the pixel circuit and a display panel.
Background
The Organic Light Emitting Diode (OLED) display panel has the advantages of low energy consumption, low production cost, self-luminescence, wide viewing angle, fast response speed, and the like, and is widely applied to the display field. When the OLED display panel switches gray scale pictures, the phenomenon of ghost shadow can occur, and the display effect of the OLED display panel is reduced.
Disclosure of Invention
The invention provides a pixel circuit, a driving method of the pixel circuit and a display panel, which are used for improving the afterimage phenomenon of the display panel.
In a first aspect, an embodiment of the present invention provides a pixel circuit, including:
a driving transistor for supplying a driving current to a light emitting device in a light emitting period, the light emitting device emitting light in response to the driving current;
the data writing module is used for writing a data signal into the grid electrode of the driving transistor in a data writing stage;
the storage module is used for maintaining the electric potential of the grid electrode of the driving transistor;
a first initialization module connected between the gate of the driving transistor and a first initialization power supply terminal, the first initialization module being configured to supply a voltage of the first initialization power supply terminal to the gate of the driving transistor in a first initialization stage;
a second initialization module connected between the gate of the driving transistor and a second initialization power supply terminal, for supplying the voltage of the second initialization power supply terminal to the gate of the driving transistor before the first initialization stage;
the voltage of the first initialization power supply terminal is less than the voltage of the second initialization power supply terminal;
and the light emitting control module, the driving transistor and the light emitting device are connected between the first driving source and the second driving source and are used for controlling connection and disconnection of the driving current path according to the light emitting control signal.
Alternatively, the voltage of the second initialization power source terminal is greater than or equal to the voltage of the first driving source.
Optionally, the second initialization power supply terminal is a light-emitting control signal input terminal.
Optionally, the second initialization module comprises a first transistor;
the gate of the first transistor is electrically connected to a first scan signal input terminal, the first pole of the first transistor is electrically connected to the second initialization power supply terminal, and the second pole of the first transistor is electrically connected to the gate of the driving transistor.
Optionally, the light emitting control module comprises a second transistor and a third transistor;
a gate of the second transistor and a gate of the third transistor are electrically connected to a light emission control signal input terminal, a first pole of the second transistor is electrically connected to the first driving source, and a second pole of the second transistor is electrically connected to the first pole of the driving transistor; a first pole of the third transistor is electrically connected to the second pole of the driving transistor, and a second pole of the third transistor is electrically connected to the anode of the light emitting device.
Optionally, the data writing module includes a fourth transistor, and the storage module includes a storage capacitor;
a gate of the fourth transistor is electrically connected to the second scan signal input terminal, a first pole of the fourth transistor is electrically connected to the first pole of the driving transistor, and a second pole of the fourth transistor is electrically connected to the data signal input terminal;
the first pole of the storage capacitor is electrically connected with the grid electrode of the driving transistor, and the second pole of the storage capacitor is electrically connected with the first driving source.
Optionally, the first initialization module includes a fifth transistor and a sixth transistor;
a gate of the fifth transistor is electrically connected to a third scan signal input terminal, a first pole of the fifth transistor is electrically connected to the first initialization power supply terminal, and a second pole of the fifth transistor is electrically connected to the gate of the driving transistor; a gate of the sixth transistor is electrically connected to the second scan signal input terminal, a first pole of the sixth transistor is electrically connected to the gate of the driving transistor, and a second pole of the sixth transistor is electrically connected to the second pole of the driving transistor.
Optionally, the pixel circuit further includes a seventh transistor; a gate of the seventh transistor is electrically connected to the first scan signal input terminal or the third scan signal input terminal, a first electrode of the seventh transistor is electrically connected to the first initialization power source terminal, and a second electrode of the seventh transistor is electrically connected to an anode of the light emitting device.
In a second aspect, an embodiment of the present invention provides a driving method for a pixel circuit, for driving the pixel circuit provided in any embodiment of the present invention, including:
a first initialization stage, wherein the voltage of a second initialization power supply end is provided to the grid of the driving transistor, and the grid of the driving transistor is initialized;
a second initialization stage, wherein the voltage of the first initialization power supply end is provided to the grid electrode of the driving transistor, and the grid electrode of the driving transistor is initialized again; wherein the voltage of the first initialization power supply terminal is less than the voltage of the second initialization power supply terminal;
a data writing stage, writing a data signal into the grid electrode of the driving transistor and maintaining the data signal;
and a light emitting stage in which the driving transistor supplies a driving current to the light emitting device, and the light emitting device emits light in response to the driving current.
In a third aspect, an embodiment of the present invention further provides a display panel including the pixel circuit provided in any embodiment of the present invention.
According to the technical scheme of the embodiment of the invention, the pixel circuit comprises a second initialization module, and in the first initialization stage, the second initialization module supplies the voltage of a second initialization power supply end to the grid electrode of the driving transistor. And the voltage of the first initialization power supply terminal is smaller than the voltage of the second initialization power supply terminal, i.e., the voltage of the second initialization power supply terminal is larger. Before the pixel circuit enters a light-emitting stage, the grid voltage of the driving transistor is increased, so that the voltage difference between the grid voltage of the driving transistor and the first electrode voltage of the driving transistor can be reduced, the grid source voltage of the driving transistor tends to zero, the hysteresis effect of the driving transistor can be weakened, the afterimage phenomenon of a display panel where the pixel circuit is located can be improved, and the display effect of the display panel is improved.
Drawings
FIG. 1 is a schematic diagram illustrating a hysteresis effect of a conventional driving transistor;
fig. 2 is a schematic structural diagram of a 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 present invention;
FIG. 4 is a timing diagram of the pixel circuit of FIG. 3;
fig. 5 is a schematic structural diagram of another 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 flowchart illustrating a driving method of a pixel circuit according to an embodiment of the invention;
fig. 9 is a schematic structural diagram of a display panel according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
In the prior art, when an OLED display panel switches pictures, one picture before switching does not disappear immediately, but gradually disappears along with the next picture, so that a short-term afterimage phenomenon exists on the OLED display panel. For example, the OLED display panel displays a black-and-white grid image, the luminance of the pixel unit corresponding to the black grid image is low, and the gate-source voltage of the driving transistor in the pixel unit corresponding to the black grid image is low. The luminance of the pixel unit corresponding to the white chess grids is high, and the grid-source voltage of the driving transistor in the pixel unit corresponding to the white chess grids is high. When the OLED display panel is switched from a picture of a black and white chess grid to a gray picture, the same data voltage is written into all the pixel circuits in the display panel, and the grid source voltage of the driving transistor of the pixel unit corresponding to the gray picture is lower than the grid source voltage of the driving transistor of the pixel unit corresponding to the white chess grid and is simultaneously higher than the grid source voltage of the driving transistor of the pixel unit corresponding to the black chess grid. At this time, the gate-source voltage of the driving transistor of the pixel cell corresponding to the black checkered grid is changed from low to high, and the light emission luminance is changed from dark to bright, and the gate-source voltage of the driving transistor of the pixel cell corresponding to the white checkered grid is changed from high to low, and the light emission luminance is changed from bright to dark. Fig. 1 is a schematic diagram illustrating a hysteresis effect of a conventional driving transistor, wherein an abscissa Vgs is a gate-source voltage of the driving transistor, and an ordinate | Id | is a current of a drain of the driving transistor. As shown in fig. 1, when the gate-source voltage Vgs of the driving transistor is decreased from large to small, the drain current curve of the driving transistor is curve 1. When the gate-source voltage Vgs of the driving transistor is increased from small to large, the drain current curve of the driving transistor is curve 2. Therefore, when the gate-source voltage of the driving transistor of the pixel unit corresponding to the black checkered grid is changed from low to high due to the hysteresis effect of the driving transistor, the gate-source voltage of the driving transistor is smaller than the gate-source voltage of the driving transistor corresponding to the gray picture in a short time, and after the picture of the pixel unit corresponding to the black checkered grid is changed into the gray picture, the light-emitting luminance is darker than the light-emitting luminance corresponding to the gray picture. When the grid-source voltage of the driving transistor of the pixel unit corresponding to the white chess grids is changed from high to low, the grid-source voltage of the driving transistor is larger than that of the driving transistor corresponding to the gray picture in a short time, and after the picture of the pixel unit corresponding to the white chess grids is changed into the gray picture, the luminous brightness is brighter than that corresponding to the gray picture, so that a short-term ghost phenomenon on the OLED display panel is caused, and the display effect of the display panel is seriously influenced.
In view of the above technical problems, embodiments of the present invention provide a pixel circuit. Fig. 2 is a schematic structural diagram of a pixel circuit according to an embodiment of the present invention. As shown in fig. 2, the pixel circuit includes:
a driving transistor Tdr for supplying a driving current to the light emitting device in a light emitting period, the light emitting device emitting light in response to the driving current;
a data writing module 10, configured to write a data signal into the gate of the driving transistor Tdr in a data writing phase;
a memory module 20 for maintaining the potential of the gate of the driving transistor Tdr;
a first initializing module 30 connected between the gate of the driving transistor Tdr and a first initializing power source terminal VREF1, the first initializing module 30 being configured to provide a voltage of a first initializing power source terminal VREF1 to the gate of the driving transistor Tdr in a first initializing stage;
a second initializing module 40 connected between the gate of the driving transistor Tdr and the second initializing power source terminal VREF2, for supplying the voltage of the second initializing power source terminal VREF2 to the gate of the driving transistor Tdr before the first initializing stage; the voltage of the first initialization power source terminal VREF1 is less than the voltage of the second initialization power source terminal VREF 2;
the light emission control module 50, the driving transistor Tdr and the light emitting device OLED are connected between the first driving source VDD and the second driving source VSS, and are configured to control connection and disconnection of the driving current path according to the light emission control signal.
In particular, the light emitting device OLED may be an organic light emitting diode. The control terminal of the data writing module 10 is electrically connected to the second scan signal input terminal S2, the first terminal of the data writing module 10 is electrically connected to the data signal input terminal Vdata, the second terminal of the data writing module 10 is electrically connected to the first pole of the driving transistor Tdr, the first terminal of the memory module 20 is electrically connected to the gate of the driving transistor Tdr, the second terminal of the first initialization module 30 and the second terminal of the second initialization module 40, the second terminal of the memory module 20 is electrically connected to the first driving source VDD of the pixel circuit, the control terminal of the first initialization module 30 is electrically connected to the third scan signal input terminal S3, the first terminal of the first initialization module 30 is electrically connected to the first initialization power terminal VREF1, the control terminal of the second initialization module 40 is electrically connected to the first scan signal input terminal S1, the first terminal of the second initialization module 40 is electrically connected to the second initialization power terminal VREF2, the light emission control module 50 includes a first light emission control module 51 and a second light emission control module 52, the control ends of the first light emitting control module 51 and the second light emitting control module 52 are electrically connected to the light emitting control signal input end EM, the first end of the first light emitting control module 51 is electrically connected to the first driving source VDD, the second end of the first light emitting control module 51 is electrically connected to the first pole of the driving transistor Tdr, the first end of the second light emitting control module 52 is electrically connected to the second pole of the driving transistor Tdr, the second end of the second light emitting control module 52 is electrically connected to the anode of the organic light emitting diode OLED, and the cathode of the organic light emitting diode OLED is electrically connected to the second driving source VSS. Illustratively, the first pole of the driving transistor Tdr is a source of the driving transistor Tdr, and the second pole of the driving transistor Tdr is a drain of the driving transistor Tdr.
The operation process of the pixel circuit may include a first initialization phase, a second initialization phase, a data write compensation phase, and a light emitting phase.
Before the display panel picture is switched, at the end of one frame, the pixel circuit is in a light-emitting stage, and the voltage of the first driving source VDD is supplied to the first pole of the driving transistor Tdr. The parasitic capacitance exists between the first electrode and the gate of the driving transistor Tdr, so that the first electrode of the driving transistor Tdr keeps the voltage of the first driving source VDD after the display panel picture is switched and in the first initialization stage of the next frame, that is, the source voltage of the driving transistor Tdr is higher. Meanwhile, in the first initialization stage of the first frame after the picture switching of the display panel, the second initialization module 40 supplies the voltage of the second initialization power source terminal VREF2 to the gate of the driving transistor Tdr. The voltage of the first initialization power supply terminal VREF1 is smaller than the voltage of the second initialization power supply terminal VREF2, that is, the voltage of the second initialization power supply terminal VREF2 is larger, and before the pixel circuit enters a light-emitting stage, the gate voltage of the driving transistor Tdr is increased, so that the voltage difference between the gate voltage of the driving transistor Tdr and the voltage of the first pole of the driving transistor Tdr can be reduced, the gate-source voltage of the driving transistor Tdr tends to zero, a hole trapped on the channel interface of the driving transistor Tdr can be released, the hysteresis effect of the driving transistor Tdr can be weakened, the afterimage phenomenon of a display panel where the pixel circuit is located can be improved, and the display effect of the display panel can be improved.
Alternatively, the voltage of the second initialization power source terminal is greater than or equal to the voltage of the first driving source.
Specifically, in the first initialization phase, the first voltage of the driving transistor is the first driving source voltage, and the gate voltage of the driving transistor is the voltage of the second initialization power supply terminal. By setting the voltage of the second initialization power supply end to be greater than or equal to the voltage of the first driving source, the gate source voltage value of the driving transistor can be greater than zero, and as can be seen from fig. 1, the hysteresis effect of the driving transistor can be further weakened at the moment, so that the image sticking phenomenon of the display panel where the pixel circuit is located can be better improved, and the display effect of the display panel is improved.
Fig. 3 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention. As shown in fig. 3, the second initialization block 40 includes a first transistor T1, a gate of the first transistor T1 is electrically connected to the first scan signal input terminal S1, a first pole of the first transistor T1 is electrically connected to the second initialization power source terminal VREF2, and a second pole of the first transistor T1 is electrically connected to the gate of the driving transistor Tdr.
Specifically, the first transistor T1 is exemplarily illustrated in fig. 3 as a P-type transistor. In the first initialization phase, the voltage inputted from the first scan signal input terminal S1 is at a low level, the first transistor T1 is turned on, and the voltage of the second initialization power source terminal VREF2 is supplied to the gate of the driving transistor Tdr.
With continued reference to fig. 3, the light emitting control module 50 includes a second transistor T2 and a third transistor T3; a gate of the second transistor T2 and a gate of the third transistor T3 are electrically connected to the emission control signal input terminal EM, a first pole of the second transistor T2 is electrically connected to the first driving source VDD, and a second pole of the second transistor T2 is electrically connected to the first pole of the driving transistor Tdr; a first pole of the third transistor T3 is electrically connected to the second pole of the driving transistor Tdr, and a second pole of the third transistor T3 is electrically connected to the anode of the light emitting device OLED.
Specifically, it is exemplarily shown in fig. 3 that the second transistor T2 and the third transistor T3 are P-type transistors. In the light emitting stage, when the voltage input by the light emitting control signal input end EM is a low level, the second transistor T2 and the third transistor T3 are turned on, and the path where the driving current provided by the driving transistor Tdr is located is communicated, so that the driving current can be provided for the organic light emitting diode OLED, and the organic light emitting diode OLED emits light.
With continued reference to fig. 3, the data writing module includes a fourth transistor T4, and the storage module includes a storage capacitor Cst; a gate electrode of the fourth transistor T4 is electrically connected to the second scan signal input terminal S2, a first electrode of the fourth transistor T4 is electrically connected to a first electrode of the driving transistor Tdr, and a second electrode of the fourth transistor T4 is electrically connected to the data signal input terminal Vdata; a first electrode of the storage capacitor Cst is electrically connected to the gate electrode of the driving transistor Tdr, and a second electrode of the storage capacitor Cst is electrically connected to the first driving source VDD. Meanwhile, the pixel circuit further includes a sixth transistor T6; a gate of the sixth transistor T6 is electrically connected to the second scan signal input terminal S2, a first pole of the sixth transistor T6 is electrically connected to the gate of the driving transistor Tdr, and a second pole of the sixth transistor T6 is electrically connected to the second pole of the driving transistor Tdr.
Specifically, the sixth transistor T6 is a compensation module. The fourth transistor T4 and the sixth transistor T6 are exemplarily shown in fig. 3 as P-type transistors. In the data writing phase, the voltage inputted from the second scan signal input terminal S2 is at a low level, the fourth transistor T4 and the sixth transistor T6 are turned on, the voltage of the data signal input terminal Vdata is provided to the first electrode of the driving transistor Tdr and is written to the gate of the driving transistor Tdr through the sixth transistor T6, and the storage capacitor Cst maintains the gate potential of the driving transistor Tdr.
With continued reference to fig. 3, the first initialization module 30 includes a fifth transistor T5; a gate of the fifth transistor T5 is electrically connected to the third scan signal input terminal S3, a first pole of the fifth transistor T5 is electrically connected to the first initialization power source terminal VREF1, and a second pole of the fifth transistor T5 is electrically connected to the gate of the driving transistor Tdr.
Specifically, it is exemplarily shown in fig. 3 that the fifth transistor T5 is a P-type transistor. In the second initialization stage, the voltage inputted from the third scan signal input terminal S3 is at a low level, the fifth transistor T5 is turned on, and the voltage of the first initialization power source terminal VREF1 is supplied to the gate of the driving transistor Tdr.
Fig. 4 is a timing diagram of the pixel circuit of fig. 3. Where S1 is a timing chart of a signal output from the first scan signal input terminal S1, S2 is a timing chart of a signal output from the second scan signal input terminal S2, S3 is a timing chart of a signal output from the third scan signal input terminal S3, EM is a timing chart of a signal output from the emission control signal input terminal EM, and Vdata is a timing chart of a signal output from the data signal input terminal Vdata. Taking P-type transistors as an example, the operation of the pixel circuit will be described with reference to fig. 3 and 4.
In the first initialization stage T1, s1 is low, s2, s3, em and vdata are high, and the first transistor T1 is turned on, and the second transistor T2, the third transistor T3, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6 and the driving transistor Tdr are turned off. The first transistor T1 supplies the voltage of the second initialization power source terminal VREF2 to the gate of the driving transistor Tdr, and the gate voltage of the driving transistor Tdr is raised. Because the first voltage of the driving transistor Tdr is the voltage of the first driving source VDD, the voltage difference between the voltage of the gate of the driving transistor Tdr and the voltage of the first pole of the driving transistor Tdr can be reduced by increasing the gate voltage of the driving transistor Tdr, so that the gate-source voltage of the driving transistor Tdr tends to zero, thereby weakening the hysteresis effect of the driving transistor Tdr, further improving the image sticking phenomenon of the display panel where the pixel circuit is located, and improving the display effect of the display panel.
In the second initialization stage T2, s3 is low, s1, s2, em and vdata are high, and the fifth transistor T5 is turned on, and the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the sixth transistor T6 and the driving transistor Tdr are turned off. The fifth transistor T5 supplies the voltage of the first initialization power source terminal VREF1 to the gate of the driving transistor Tdr. The voltage of the first initialization power source terminal VREF1 is low, and initializes the gate of the driving transistor Tdr. The driving transistor Tdr is in an on state at this time.
In the data writing phase T3, s2 and vdata are low, s1, s3 and em are high, the fourth transistor T4 and the sixth transistor T6 are turned on, and the first transistor T1, the second transistor T2, the third transistor T3 and the fifth transistor T5 are turned off. The data signal inputted from the data signal input terminal Vdata is written to the gate of the driving transistor Tdr through the fourth transistor T4, the driving transistor Tdr, and the sixth transistor T6, and the data signal is stored through the storage capacitor Cst until the gate voltage of the driving transistor Tdr becomes Vdata + vth, and the driving transistor Tdr is turned off. Where vth is the threshold voltage of the driving transistor Tdr. Therefore, in the data writing phase t3, the pixel circuit completes the writing of the data voltage and the threshold compensation of the driving transistor Tdr.
In the lighting period T4, em is low, s1, s2, s3 and vdata are high, the second transistor T2 and the third transistor T3 are turned on, and the first transistor T1, the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 are turned off. The voltage of the first driving source VDD is written into the first pole of the driving transistor Tdr through the second transistor T2, the driving transistor Tdr is turned on by the voltage of the first driving source VDD, and forms a driving current according to the gate voltage vdata + vth of the driving transistor Tdr, i.e. the driving current is I ═ K (vda + vth) -vth)2＝K(vdd-vdata+vth-vth)2＝K(vdd-vdata)2And driving the organic light emitting diode OLED to emit light.
It should be noted that the display panel may include a plurality of rows of pixel circuits, and each row of pixel circuits includes a scan signal input terminal for inputting a scan signal. At this time, the first scan signal input terminal S1 in the pixel circuit of the nth row may multiplex the scan signal input terminals of the pixel circuits of the (n-2) th row, the third scan signal input terminal S3 in the pixel circuit of the nth row may multiplex the scan signal input terminals of the pixel circuits of the (n-1) th row, the second scan signal input terminal S2 in the pixel circuit of the nth row adopts the scan signal input terminal of the nth row, and so on. Therefore, on the basis of being capable of normally driving the pixel circuits, the setting of the scanning signal input end in each row of pixel circuits is reduced, the setting of scanning signal lines in the display panel can be reduced, the narrow frame design of the display panel is facilitated, and the display effect of the display panel is improved.
Fig. 5 is a schematic structural diagram of another pixel circuit according to an embodiment of the invention. As shown in fig. 5, the second initialization power source terminal VREF2 may be the emission control signal input terminal EM.
Specifically, as can be seen from fig. 4, the emission control signal EM inputted from the emission control signal input terminal EM is at a high level during the first initialization period t1, the second initialization period t2 and the data writing period t3, and is at a low level during the emission period t 4. Therefore, in fig. 5, the light-emitting control signal input end EM is multiplexed as the second initialization power source terminal VREF2, and in the first initialization period t1, the light-emitting control signal input end EM can provide a high level voltage for the gate of the driving transistor Tdr, so that on the basis of weakening the hysteresis effect of the driving transistor Tdr and improving the afterimage phenomenon of the display panel where the pixel circuit is located, the routing corresponding to the second initialization power source terminal VREF2 can be avoided being separately arranged, the pixel circuit is simplified, and the display panel is suitable for a higher resolution display panel. Meanwhile, compared with the pixel circuit which is provided with the wiring corresponding to the second initialization power supply end independently, the multiplexing light-emitting control signal line can reduce the wiring of the pixel circuit and reduce the process flow for manufacturing the pixel circuit, thereby reducing the process defects of the pixel circuit, being beneficial to improving the product yield and being beneficial to the narrow-frame design of the display panel.
Fig. 6 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention. As shown in fig. 6, the pixel circuit further includes a seventh transistor T7; a gate of the seventh transistor T7 is electrically connected to the first scan signal input terminal S1, a first pole of the seventh transistor T7 is electrically connected to the first initialization power source terminal VREF1, and a second pole of the seventh transistor T7 is electrically connected to the anode of the light emitting device OLED.
Specifically, with continued reference to fig. 4 and 6, at the first initializing period T1, s1 is low, the seventh transistor T7 is turned on, and the voltage of the first initializing power source terminal VREF1 is written to the anode of the light emitting device OLED to initialize the anode of the light emitting device OLED. At this time, the anode of the light emitting device OLED is initialized and the gate voltage of the driving transistor Tdr is increased to the same stage, so that the driving efficiency of the pixel circuit can be improved.
Fig. 7 is a schematic structural diagram of another pixel circuit according to an embodiment of the invention. As shown in fig. 7, unlike fig. 6, the gate of the seventh transistor T7 is electrically connected to the third scan signal input terminal S3.
Specifically, with continued reference to fig. 4 and 7, at the second initializing period T2, s3 is low, the seventh transistor T7 is turned on, and the voltage of the first initializing power source terminal VREF1 is written to the anode of the light emitting device OLED to initialize the anode of the light emitting device OLED. At this time, the anode of the light emitting device OLED and the gate of the driving transistor Tdr are initialized at the same stage, and the driving efficiency of the pixel circuit can be improved as well.
The embodiment of the invention also provides a driving method of the pixel circuit, which is used for driving the pixel circuit provided by any embodiment of the invention. Fig. 8 is a flowchart illustrating a driving method of a pixel circuit according to an embodiment of the invention. As shown in fig. 8, the method includes:
s101, in the first initialization stage, the voltage of the second initialization power supply end is supplied to the grid electrode of the driving transistor, and the grid electrode of the driving transistor is initialized.
S102, in a second initialization stage, the voltage of the first initialization power supply end is supplied to the grid electrode of the driving transistor, and the grid electrode of the driving transistor is initialized again; wherein the voltage of the first initialization power supply terminal is less than the voltage of the second initialization power supply terminal.
And S103, in the data writing stage, writing a data signal into the grid electrode of the driving transistor and maintaining the data signal.
And S104, in a light emitting stage, the driving transistor provides driving current for the light emitting device, and the light emitting device emits light in response to the driving current.
According to the technical scheme of the embodiment of the invention, the voltage of the second initialization power supply end is supplied to the grid electrode of the driving transistor in the first initialization stage. And the voltage of the first initialization power supply terminal is smaller than the voltage of the second initialization power supply terminal, i.e., the voltage of the second initialization power supply terminal is larger. Before the pixel circuit enters a light-emitting stage, the grid voltage of the driving transistor is increased, so that the voltage difference between the grid voltage of the driving transistor and the first electrode voltage of the driving transistor can be reduced, the grid source voltage of the driving transistor tends to zero, the hysteresis effect of the driving transistor can be weakened, the afterimage phenomenon of a display panel where the pixel circuit is located can be improved, and the display effect of the display panel is improved.
The embodiment of the invention also provides a display panel. Fig. 9 is a schematic structural diagram of a display panel according to an embodiment of the present invention. As shown in fig. 9, the display panel includes a substrate 100 and a plurality of pixel units 110 located on the substrate 100, the display panel may further include a plurality of scanning signal lines 120 and a plurality of data signal lines 130 located on the substrate 100, the pixel circuit units may be disposed in a space formed by the scanning signal lines 120 and the data signal lines 130 crossing each other, the pixel units 110 may communicate with the data signal lines 130 electrically connected thereto under the action of scanning signals input by the scanning signal lines 120 electrically connected thereto, and the data signal lines 130 transmit data signals to the corresponding pixel units 110, thereby implementing the display function of the display device.
The pixel unit 110 includes the pixel circuit provided in any embodiment of the present invention, and therefore has the same advantages as the pixel driving circuit provided in any embodiment of the present invention, and details thereof are not repeated herein. The display panel can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame and the like.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A pixel circuit, comprising:
a driving transistor for supplying a driving current to a light emitting device in a light emitting period, the light emitting device emitting light in response to the driving current;
the data writing module is used for writing a data signal into the grid electrode of the driving transistor in a data writing stage;
the storage module is used for maintaining the electric potential of the grid electrode of the driving transistor;
a first initialization module connected between the gate of the driving transistor and a first initialization power supply terminal, the first initialization module being configured to supply a voltage of the first initialization power supply terminal to the gate of the driving transistor in a first initialization stage;
a second initialization module connected between the gate of the driving transistor and a second initialization power supply terminal, for supplying the voltage of the second initialization power supply terminal to the gate of the driving transistor before the first initialization stage;
the voltage of the first initialization power supply terminal is less than the voltage of the second initialization power supply terminal;
and the light emitting control module, the driving transistor and the light emitting device are connected between the first driving source and the second driving source and are used for controlling connection and disconnection of the driving current path according to the light emitting control signal.
2. The pixel circuit according to claim 1, wherein a voltage of the second initialization power supply terminal is greater than or equal to a voltage of the first driving source.
3. The pixel circuit according to claim 2, wherein the second initialization power supply terminal is a light emission control signal input terminal.
4. The pixel circuit according to claim 1, wherein the second initialization module comprises a first transistor;
the gate of the first transistor is electrically connected to a first scan signal input terminal, the first pole of the first transistor is electrically connected to the second initialization power supply terminal, and the second pole of the first transistor is electrically connected to the gate of the driving transistor.
5. The pixel circuit according to claim 4, wherein the light emission control module includes a second transistor and a third transistor;
a gate of the second transistor and a gate of the third transistor are electrically connected to a light emission control signal input terminal, a first pole of the second transistor is electrically connected to the first driving source, and a second pole of the second transistor is electrically connected to the first pole of the driving transistor; a first pole of the third transistor is electrically connected to the second pole of the driving transistor, and a second pole of the third transistor is electrically connected to the anode of the light emitting device.
6. The pixel circuit according to claim 5, wherein the data writing block comprises a fourth transistor, and the storage block comprises a storage capacitor;
a gate of the fourth transistor is electrically connected to the second scan signal input terminal, a first pole of the fourth transistor is electrically connected to the first pole of the driving transistor, and a second pole of the fourth transistor is electrically connected to the data signal input terminal;
the first pole of the storage capacitor is electrically connected with the grid electrode of the driving transistor, and the second pole of the storage capacitor is electrically connected with the first driving source.
7. The pixel circuit according to claim 6, wherein the first initialization block comprises a fifth transistor and a sixth transistor;
a gate of the fifth transistor is electrically connected to a third scan signal input terminal, a first pole of the fifth transistor is electrically connected to the first initialization power supply terminal, and a second pole of the fifth transistor is electrically connected to the gate of the driving transistor; a gate of the sixth transistor is electrically connected to the second scan signal input terminal, a first pole of the sixth transistor is electrically connected to the gate of the driving transistor, and a second pole of the sixth transistor is electrically connected to the second pole of the driving transistor.
8. The pixel circuit according to claim 7, further comprising a seventh transistor; a gate of the seventh transistor is electrically connected to the first scan signal input terminal or the third scan signal input terminal, a first electrode of the seventh transistor is electrically connected to the first initialization power source terminal, and a second electrode of the seventh transistor is electrically connected to an anode of the light emitting device.
9. A driving method of a pixel circuit for driving the pixel circuit according to any one of claims 1 to 8, comprising:
a first initialization stage, wherein the voltage of a second initialization power supply end is provided to the grid of the driving transistor, and the grid of the driving transistor is initialized;
a second initialization stage, wherein the voltage of the first initialization power supply end is provided to the grid electrode of the driving transistor, and the grid electrode of the driving transistor is initialized again; wherein the voltage of the first initialization power supply terminal is less than the voltage of the second initialization power supply terminal;
a data writing stage, writing a data signal into the grid electrode of the driving transistor and maintaining the data signal;
and a light emitting stage in which the driving transistor supplies a driving current to the light emitting device, and the light emitting device emits light in response to the driving current.
10. A display panel comprising the pixel circuit according to any one of claims 1 to 8.
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| CN202010183703.8A CN111354314A (en) | 2020-03-16 | 2020-03-16 | Pixel circuit, driving method of pixel circuit and display panel |
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| CN202010183703.8A CN111354314A (en) | 2020-03-16 | 2020-03-16 | Pixel circuit, driving method of pixel circuit and display panel |
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| CN112509518A (en) * | 2020-11-27 | 2021-03-16 | 合肥维信诺科技有限公司 | Pixel circuit, driving method thereof and display panel |
| CN112908245A (en) * | 2021-02-24 | 2021-06-04 | 昆山国显光电有限公司 | Pixel circuit, driving method thereof and display panel |
| CN113450715A (en) * | 2021-06-25 | 2021-09-28 | 京东方科技集团股份有限公司 | Display substrate, preparation method thereof and display device |
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| CN114882837A (en) * | 2022-04-26 | 2022-08-09 | Oppo广东移动通信有限公司 | Pixel driving circuit, control method, display screen and display device |
| CN114974110A (en) * | 2022-04-26 | 2022-08-30 | Oppo广东移动通信有限公司 | Pixel driving circuit, control method, display screen and display device |
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