CN113781961B - Pixel circuit, display panel and driving method - Google Patents
Pixel circuit, display panel and driving method Download PDFInfo
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- CN113781961B CN113781961B CN202111254467.5A CN202111254467A CN113781961B CN 113781961 B CN113781961 B CN 113781961B CN 202111254467 A CN202111254467 A CN 202111254467A CN 113781961 B CN113781961 B CN 113781961B
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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]
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0243—Details of the generation of driving signals
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0264—Details of driving circuits
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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
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
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- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
According to the pixel circuit, the display panel and the driving method, the first initialization circuit is added in the pixel circuit and is used for responding to the second scanning signal, the first initialization signal is written into the second stage of the driving transistor for generating the coupling capacitor, and the effective level time of the second scanning signal is before the effective level time of the light-emitting control signal. The first initialization signal can effectively eliminate charges accumulated in the coupling capacitance occurring in the pixel circuit, and since the second scan signal can effectively eliminate charges accumulated in the coupling capacitance in the pixel circuit before the driving transistor drives the light emitting device to emit light, the stability of light emission of the display device can be improved.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a pixel circuit, a display panel, and a driving method.
Background
Organic light emitting diode (Organic Light Emitting Diode, OLED) panels have been receiving great attention because of their flexibility, high contrast, low power consumption, and the like. The pixel circuit is the core technical content of the OLED panel and has important research significance.
At present, an OLED screen pixel circuit generally adopts a combined design of a plurality of TFTs (Thin Film Transistor, thin film field effect transistors) and a capacitor, and the pixel circuit can effectively solve various problems of non-uniformity of pixels, unstable writing of voltage and the like. However, due to the process, a coupling phenomenon occurs in the pixel circuit, and a coupling capacitance is generated, and the coupling capacitance causes interference to a normal display signal due to accumulation of charges and release of charges, so that an unstable flicker phenomenon occurs in the light emission of the OLED, and the display performance is affected.
Disclosure of Invention
The embodiment of the invention provides a pixel circuit, a display panel and a driving method, which are used for solving the problem of unstable light emission of an OLED display panel in the prior art.
In a first aspect, an embodiment of the present invention provides a pixel circuit, including:
a light emitting device configured to emit light under control of a driving current;
a driving transistor configured to generate the driving current according to a data signal;
a light emission control circuit configured to turn on a first stage of the driving transistor and supply the driving current to the light emitting device in response to a light emission control signal;
a write compensation circuit configured to write a data signal to the driving transistor in response to a first scan signal, and to compensate a threshold voltage of the driving transistor;
a storage circuit configured to store a gate potential of the driving transistor;
a reset circuit configured to reset a gate of the driving transistor in response to a reset signal;
a first initializing circuit for writing a first initializing signal to a second stage of the driving transistor in response to a second scanning signal;
wherein the second scan signal active level time is before the light emission control signal active level time.
In one possible implementation, the second scan signal active level time is subsequent to the first scan signal active level time.
In one possible implementation, the method further comprises a second initialization circuit;
the second initialization circuit is configured to write a second initialization signal to an anode of the light emitting device in response to the first scan signal.
In one possible implementation, the first initialization circuit includes a first transistor;
the grid electrode of the first transistor is electrically connected with the second scanning signal end, the first electrode of the first transistor is electrically connected with the second electrode of the driving transistor, and the second electrode of the first transistor is electrically connected with the first initialization signal end.
In one possible implementation, the light emission control circuit includes a second transistor and a third transistor;
the grid electrode of the second transistor is electrically connected with the light-emitting control signal end, the first stage of the second transistor is electrically connected with the first voltage signal end, and the second stage of the second transistor is electrically connected with the first stage of the driving transistor;
the grid electrode of the third transistor is electrically connected with the light-emitting control signal end, the first stage of the third transistor is electrically connected with the second stage of the driving transistor, and the second stage of the third transistor is electrically connected with the anode electrode of the light-emitting device.
In one possible implementation, the write compensation circuit includes a fourth transistor and a fifth transistor;
the grid electrode of the fourth transistor is electrically connected with the first scanning signal end, the first stage of the fourth transistor is electrically connected with the first stage of the driving transistor, and the second stage of the fourth transistor is electrically connected with the data signal end;
the grid electrode of the fifth transistor is electrically connected with the first scanning signal end, the first stage of the fifth transistor is electrically connected with the grid electrode of the driving transistor, and the second stage of the fifth transistor is electrically connected with the second stage of the driving transistor.
In one possible implementation, the reset circuit includes a sixth transistor;
the grid electrode of the sixth transistor is electrically connected with the reset signal end, the first stage of the sixth transistor is electrically connected with the grid electrode of the driving transistor, and the second stage of the sixth transistor is electrically connected with the second initialization signal end.
In one possible implementation, a first end of the capacitor is electrically connected to a reference voltage end, and a second end of the capacitor is electrically connected to a gate of the driving transistor.
In one possible implementation, the second initialization circuit includes a seventh transistor;
the grid electrode of the seventh transistor is electrically connected with the first scanning signal end, the first stage of the seventh transistor is electrically connected with the anode of the light emitting device, and the second stage of the seventh transistor is electrically connected with the second initialization signal end.
In a second aspect, an embodiment of the present invention further provides a display panel, including a pixel circuit as described in any one of the foregoing.
In a third aspect, an embodiment of the present invention further provides a driving method of a pixel circuit, where the pixel circuit includes a light emitting device, a driving transistor, a light emission control circuit, a write compensation circuit, a memory circuit, a reset circuit, and a first initialization circuit;
the driving method includes: a reset phase, a write compensation phase, a pre-light-emitting phase, and a light-emitting phase;
in the reset stage, the reset circuit responds to a reset signal to reset the grid electrode of the driving transistor;
in the write compensation stage, the write compensation circuit is responsive to a first scan signal to write a data signal to the drive transistor and to compensate for a threshold voltage of the drive transistor;
in the pre-light emitting stage, the first initializing circuit responds to a second scanning signal and writes the first initializing signal into a second stage of the driving transistor;
in the light emitting stage, the light emission control circuit makes a first stage of the driving transistor turn on a voltage in response to a light emission control signal and supplies the driving current to the light emitting device;
wherein the second scan signal active level time is before the light emission control signal active level time.
In one possible implementation, the second scan signal active level time is subsequent to the first scan signal active level time.
In one possible implementation, the pixel circuit further includes a second initialization circuit, the method further including:
in the write compensation stage, the second initialization circuit writes a second initialization signal to an anode of the light emitting device in response to the first scan signal.
The beneficial effects are that:
according to the pixel circuit, the display panel and the driving method provided by the embodiment of the invention, the first initialization circuit is added in the pixel circuit and is used for responding to the second scanning signal, the first initialization signal is written into the second stage of the driving transistor for generating the coupling capacitor, wherein the effective level time of the second scanning signal is before the effective level time of the light-emitting control signal. The first initialization signal can effectively eliminate charges accumulated in the coupling capacitance occurring in the pixel circuit, and since the second scan signal can effectively eliminate charges accumulated in the coupling capacitance in the pixel circuit before the driving transistor drives the light emitting device to emit light, the stability of light emission of the display device can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a pixel circuit in the prior art according to an embodiment of the present invention;
FIG. 2 is a timing diagram of a pixel circuit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 4 is a timing diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a driving method of a pixel circuit according to an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating operation of a pixel circuit in a reset phase according to an embodiment of the present invention;
FIG. 7 is a schematic timing diagram of a pixel circuit in a reset phase according to an embodiment of the present invention;
FIG. 8 is a schematic diagram illustrating the operation of a pixel circuit during a write compensation phase according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a pixel circuit timing diagram during a write compensation stage according to an embodiment of the present invention;
FIG. 10 is a schematic diagram illustrating the operation of a pixel circuit in a pre-light emitting stage according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of a timing sequence of a pixel circuit in a pre-light emitting stage according to an embodiment of the present invention;
FIG. 12 is a schematic diagram of a pixel circuit in a light-emitting stage according to an embodiment of the present invention;
FIG. 13 is a schematic timing diagram of a pixel circuit in a light-emitting stage according to an embodiment of the present invention;
fig. 14 is a schematic timing diagram of a pixel circuit in a 1-frame period according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. And embodiments of the invention and features of the embodiments may be combined with each other without conflict. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
It should be noted that the dimensions and shapes of the figures in the drawings do not reflect true proportions, and are intended to illustrate the present invention only. And the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
At present, a pixel circuit of an OLED (Organic Light Emitting Diode ) screen generally adopts a combined design of a plurality of TFTs (Thin Film Transistor, thin film field effect transistors) and a capacitor C, for example, the pixel circuit shown in fig. 1, which can effectively solve various problems such as non-uniformity of pixels and unstable writing of voltages, and fig. 2 is a timing chart of the circuit. Due to the process, a coupling phenomenon occurs in the pixel circuit, that is, the coupling capacitor Co is generated at the node N1 in fig. 1, and the coupling capacitor Co interferes with the normal display signal, thereby adversely affecting the display effect.
The coupling capacitance Co here is a capacitance generated by coupling, and is not a capacitance actually existing.
In order to solve the above-mentioned problems, an embodiment of the present invention provides a pixel circuit, as shown in fig. 3, including:
a light emitting device L configured to emit light under control of a driving current;
a driving transistor DT configured to generate a driving current according to the data signal data;
a light emission control circuit 10 configured to turn on a first stage of the driving transistor DT and supply a driving current to the light emitting device L in response to a light emission control signal em;
a write compensation circuit 20 configured to write the data signal data to the driving transistor DT in response to the first scan signal gate1 and compensate a threshold voltage of the driving transistor DT;
a memory circuit 30 configured to store a gate potential of the driving transistor DT;
a reset circuit 40 configured to reset the gate of the driving transistor DT in response to a reset signal reset;
a first initializing circuit 50 for writing a first initializing signal vinit1 to the second stage of the driving transistor DT in response to the second scan signal gate 2;
the active level time of the second scan signal gate2 is before the active level time of the light emission control signal em.
The pixel circuit provided by the embodiment of the invention comprises a light emitting device L, a driving transistor DT, a light emitting control circuit 10, a write compensation circuit 20, a storage circuit 30, a reset circuit 40 and a first initialization circuit 50, wherein the light emitting device L emits light under the control of a driving current, the driving transistor DT generates the driving current according to a data signal data, the light emitting control circuit 10 responds to a light emitting control signal em to enable a first stage of the driving transistor DT to be turned on and provide the driving current for the light emitting device L, the write compensation circuit 20 responds to a first scanning signal gate1 to write the data signal data into the driving transistor DT and compensate the threshold voltage of the driving transistor DT, the storage circuit 30 stores the gate potential of the driving transistor DT, the reset circuit 40 responds to a reset signal reset to reset the gate of the driving transistor DT, the first initialization circuit 50 responds to a second scanning signal gate2 to write the first initialization signal vinit1 into a second stage of the driving transistor DT, and the second scanning signal gate2 has an effective level time before the effective level time of the light emitting control signal em. Since the first initializing circuit 50 can write the first initializing signal vinit1 into the second stage of the driving transistor DT in response to the second scan signal gate2, and the second scan signal gate2 has an active level time before the active level time of the light emission control signal em, the coupling capacitance in the pixel circuit can be effectively eliminated before the driving transistor DT drives the light emitting device L to emit light, so that the light emission stability of the display device can be improved.
In implementation, as shown in fig. 3, the pixel circuit further includes a second initialization circuit 60 configured to write a second initialization signal vinit2 to the anode of the light emitting device L in response to the first scan signal gate 1.
The second initializing circuit 60 may initialize the anode of the light emitting device L, and remove charges at the anode of the light emitting device L, so that the display effect may be improved.
In implementation, as shown in fig. 3, the first initializing circuit 50 may include a first transistor T1, the light emission control circuit 10 may include a second transistor T2 and a third transistor T3, the write compensation circuit 20 may include a fourth transistor T4 and a fifth transistor T5, the reset circuit 40 may include a sixth transistor T6, the second initializing circuit 60 may include a seventh transistor T7, and the memory circuit 30 may include a capacitor C.
Specifically, the Gate of the first transistor T1 is electrically connected to the second scan signal terminal Gate2, the first pole of the first transistor T1 is electrically connected to the second pole of the driving transistor DT, and the second pole of the first transistor T1 is electrically connected to the first initialization signal terminal Vinit 1; the grid electrode of the second transistor T2 is electrically connected with the light-emitting control signal end EM, the first stage of the second transistor T2 is electrically connected with the first voltage signal end VDD, and the second stage of the second transistor T2 is electrically connected with the first stage of the driving transistor DT; the grid electrode of the third transistor T3 is electrically connected with the light-emitting control signal end EM, the first stage of the third transistor T3 is electrically connected with the second stage of the driving transistor DT, and the second stage of the third transistor T3 is electrically connected with the anode of the light-emitting device L; the grid electrode of the fourth transistor T4 is electrically connected with the first scanning signal end Gate1, the first stage of the fourth transistor T4 is electrically connected with the first stage of the driving transistor DT, and the second stage of the fourth transistor T4 is electrically connected with the Data signal end Data; the grid electrode of the fifth transistor T5 is electrically connected with the first scanning signal end Gate1, the first stage of the fifth transistor T5 is electrically connected with the grid electrode of the driving transistor DT, and the second stage of the fifth transistor T5 is electrically connected with the second stage of the driving transistor DT; the grid electrode of the sixth transistor T6 is electrically connected with the Reset signal end Reset, the first stage of the sixth transistor T6 is electrically connected with the grid electrode of the driving transistor DT, and the second stage of the sixth transistor T6 is electrically connected with the second initialization signal end Vinit 2; the grid electrode of the seventh transistor T7 is electrically connected with the first scanning signal end Gate1, the first stage of the seventh transistor T7 is electrically connected with the anode of the light emitting device L, and the second stage of the seventh transistor T7 is electrically connected with the second initialization signal end Vinit 2; the first end of the capacitor C is electrically connected with the reference voltage end Vref, and the second end of the capacitor C is electrically connected with the grid electrode of the driving transistor DT; the cathode of the light emitting device L is electrically connected to the second voltage signal terminal VSS.
The light emission control signal terminal EM is configured to output a light emission control signal EM, the first scan signal terminal Gate1 is configured to output a first scan signal Gate1, the second scan signal terminal Gate2 is configured to output a second scan signal Gate2, the Reset signal terminal Reset is configured to output a Reset signal Reset, the first initialization signal terminal Vinit1 is configured to output a first initialization signal Vinit1, the second initialization signal terminal Vinit2 is configured to output a second initialization signal Vinit2, the Data signal terminal Data is configured to output a Data signal Data, the first voltage signal terminal VDD is configured to output a first voltage VDD, the second voltage signal terminal VSS is configured to output a second voltage VSS, and the reference voltage terminal Vref is configured to output a reference voltage Vref.
It should be noted that, in the embodiment of the present invention, the first initialization signal vinit1, the second initialization signal vinit2, and the first voltage signal vdd may be constant voltage dc signals or time-hopped ac signals, which are specifically set according to practical situations, and the present invention does not limit this.
In a specific implementation, the reference voltage terminal Vref may be the same as the first voltage signal terminal VDD, and the first voltage signal VDD output by the first voltage signal terminal VDD is a constant voltage dc signal, so as to implement the holding function of the capacitor.
Based on the same inventive concept, the embodiment of the present invention further provides a driving method matched with the above pixel circuit, as shown in fig. 5, including:
s501, in a reset stage, a reset circuit responds to a reset signal to reset the grid electrode of the driving transistor;
s502, in a writing compensation stage, a writing compensation circuit responds to a first scanning signal, writes a data signal into a driving transistor and compensates the threshold voltage of the driving transistor;
s503, in a pre-light emitting stage, the first initialization circuit responds to the second scanning signal and writes the first initialization signal into a second stage of the driving transistor;
s504, in the light emitting stage, the light emitting control circuit responds to the light emitting control signal, enables the first stage of the driving transistor to be connected with the voltage, and provides driving current for the light emitting device, wherein the second scanning signal effective level time is before the light emitting control signal effective level time.
Optionally, the method further comprises:
the second scan signal gate2 is active level time after the first scan signal gate 1.
In the write compensation phase, the second initialization circuit 60 writes the second initialization signal vinit2 to the anode of the light emitting device L in response to the first scan signal gate 1.
Alternatively, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 3, the driving transistor DT and the first transistor T1 to the seventh transistor T7 may be P-type transistors. Of course, N-type transistors may be used, and the present invention is not limited thereto.
Specifically, in the pixel circuit provided by the embodiment of the invention, the P-type transistor is turned on under the action of a low-level signal and turned off under the action of a high-level signal; the N-type transistor is turned on under the action of a high-level signal and turned off under the action of a low-level signal.
Therefore, when all the transistors in the pixel circuit provided by the embodiment of the invention are P-type transistors, the signal of the active level mentioned in the driving method is a signal of low level, and the signal of the off level is a signal of high level.
Specifically, in the pixel circuit provided in the embodiment of the present invention, each of the above transistors may be a thin film transistor (TFT, thin Film Transistor) or a metal oxide semiconductor field effect transistor (MOS, metal Oxide Scmiconductor), which is not limited herein. The first electrode of the transistor may be used as a source electrode, the second electrode may be used as a drain electrode, or the first electrode of the transistor may be used as a drain electrode, and the second electrode may be used as a source electrode, depending on the types of the transistors and the signals of the gates of the transistors, which are not particularly distinguished herein.
The present invention will be described in detail with reference to specific examples. The present embodiment is for better explaining the present invention, but not limiting the present invention. In the following description, a high level is indicated by 1, and a low level is indicated by 0. It should be noted that 1 and 0 are logic levels, which are only used to better explain the specific operation of the pixel circuit, not specific voltage values.
Next, the operation of the pixel circuit shown in fig. 3 will be described by selecting 4 phases of the first phase t1, the second phase t2, the third phase t3 and the fourth phase t4 in the signal timing diagram shown in fig. 4.
In the first phase t1, i.e., the reset phase, as shown in fig. 6 and 7, reset=0, gate1=1, gate2=1, em=1.
reset=0, the sixth transistor T6 is turned on, the sixth transistor T6 writes the second initialization signal vinit2 to the gate of the driving transistor DT, and resets the gate of the driving transistor DT; gate 1=1, and the fourth transistor T4, the fifth transistor T5, and the seventh transistor T7 are turned off; gate 2=1, the first transistor T1 is turned off; em=1, the second transistor T2 and the third transistor T3 are turned off.
In the second phase t2, i.e., the write compensation phase, as shown in fig. 8 and 9, reset=1, gate1=0, gate2=1, em=1.
reset=1, the sixth transistor T6 is turned off; gate 1=0, the fourth transistor T4 is turned on, the fourth transistor T4 writes the Data signal Data into the driving transistor DT, the fifth transistor T5 is turned on, the gate of the driving transistor DT is turned on with the second diode to form a diode structure, the Data signal terminal Data charges the gate of the driving transistor DT and the capacitor C, the threshold voltage of the driving transistor DT is compensated until the gate voltage of the driving transistor DT is vdata+vth, the driving transistor DT is turned off, the seventh transistor T7 is turned on, and the second initialization signal vinit2 is written into the anode of the light emitting device L to reset it; gate 2=1, the first transistor T1 is turned off; em=1, the second transistor T2 and the third transistor T3 are turned off.
In the third phase t3, i.e., the pre-light emission phase, as shown in fig. 10 and 11, reset=1, gate1=1, gate2=0, em=1.
reset=1, the sixth transistor T6 is turned off; gate 1=1, and the fourth transistor T4, the fifth transistor T5, and the seventh transistor T7 are turned off; gate 2=0, the first transistor T1 is turned on, and the first initialization signal vinit2 is written into the second stage of the driving transistor DT, i.e., the N1 node, through the first transistor T1 to eliminate the charge accumulated in the coupling capacitor generated by the coupling phenomenon in the second stage of the driving transistor DT; em=1, the second transistor T2 and the third transistor T3 are turned off.
In the fourth phase t4, i.e., the light-emitting phase, as shown in fig. 12 and 13, reset=1, gate1=1, gate2=1, em=0.
reset=1, the sixth transistor T6 is turned off; gate 1=1, and the fourth transistor T4, the fifth transistor T5, and the seventh transistor T7 are turned off; gate 2=1, the first transistor T1 is turned off; em=0, the second transistor T2 and the third transistor T3 are turned on, the first stage of the driving transistor DT is turned on, and a driving current is supplied to the light emitting device L to emit light.
As can be seen from the above-mentioned process and the timing chart shown in fig. 4, the active level time of the second scan signal gate2 is before the active level time of the light emission control signal em, that is, the first initialization signal vinit1 provided in the embodiment of the present invention is written into the position where the second stage of the driving transistor DT generating the coupling capacitor is located before the light emission stage, so that the accumulated charges are eliminated before the light emission stage, and the first initialization circuit 50 does not operate during the light emission stage, so that the normal light emission can be ensured.
It should be noted that in the embodiment of the present invention, the light emission control signal em may be turned on for multiple times in 1frame (1 frame) of time, but the data signal data is written only once, as shown in fig. 14, the valid level signal of the light emission control signal em appears 2 times, that is, light emission is 2 times, but the data signal data is written only once in each frame of time, that is, no matter how many times the data signal is written, before the light emission control signal em is the valid level signal, the second scan signal gate2 must be the valid level signal, so that the charge accumulated by the generated coupling capacitor can be eliminated before the light emission device emits light, and the light emission stability of the display device is improved.
Based on the same inventive concept, an embodiment of the present invention also provides a display panel including any one of the pixel circuits of the previous embodiments.
According to the pixel circuit, the display panel and the driving method provided by the embodiment of the invention, the first initializing circuit 50 is added in the pixel circuit and is used for responding to the second scanning signal gate2, the first initializing signal vinit1 is written into the second stage of the driving transistor DT for generating the coupling capacitance, the first initializing signal vinit1 can effectively eliminate the coupling capacitance in the pixel circuit, and the coupling capacitance in the pixel circuit can be effectively eliminated before the driving transistor DT drives the light emitting device L to emit light because the effective level time of the second scanning signal gate2 is before the effective level time of the light emitting control signal em, so that the light emitting stability of the display device can be improved.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (12)
1. A pixel circuit, comprising:
a light emitting device configured to emit light under control of a driving current;
a driving transistor configured to generate the driving current according to a data signal;
a light emission control circuit configured to turn on a first stage of the driving transistor and supply the driving current to the light emitting device in response to a light emission control signal;
a write compensation circuit configured to write a data signal to the driving transistor in response to a first scan signal, and to compensate a threshold voltage of the driving transistor;
a storage circuit configured to store a gate potential of the driving transistor;
a reset circuit configured to reset a gate of the driving transistor in response to a reset signal;
a first initializing circuit for writing a first initializing signal to a second stage of the driving transistor in response to a second scanning signal;
wherein, in a frame time, the second scanning signal active level time is before the light emitting control signal active level time, and the second scanning signal active level time is after the first scanning signal active level time.
2. The pixel circuit of claim 1, further comprising a second initialization circuit;
the second initialization circuit is configured to write a second initialization signal to an anode of the light emitting device in response to the first scan signal.
3. The pixel circuit of claim 1, wherein the first initialization circuit comprises a first transistor;
the grid electrode of the first transistor is electrically connected with the second scanning signal end, the first electrode of the first transistor is electrically connected with the second electrode of the driving transistor, and the second electrode of the first transistor is electrically connected with the first initialization signal end.
4. The pixel circuit according to claim 1, wherein the light emission control circuit includes a second transistor and a third transistor;
the grid electrode of the second transistor is electrically connected with the light-emitting control signal end, the first stage of the second transistor is electrically connected with the first voltage signal end, and the second stage of the second transistor is electrically connected with the first stage of the driving transistor;
the grid electrode of the third transistor is electrically connected with the light-emitting control signal end, the first stage of the third transistor is electrically connected with the second stage of the driving transistor, and the second stage of the third transistor is electrically connected with the anode electrode of the light-emitting device.
5. The pixel circuit according to claim 1, wherein the write compensation circuit includes a fourth transistor and a fifth transistor;
the grid electrode of the fourth transistor is electrically connected with the first scanning signal end, the first stage of the fourth transistor is electrically connected with the first stage of the driving transistor, and the second stage of the fourth transistor is electrically connected with the data signal end;
the grid electrode of the fifth transistor is electrically connected with the first scanning signal end, the first stage of the fifth transistor is electrically connected with the grid electrode of the driving transistor, and the second stage of the fifth transistor is electrically connected with the second stage of the driving transistor.
6. The pixel circuit according to claim 1, wherein the reset circuit includes a sixth transistor;
the grid electrode of the sixth transistor is electrically connected with the reset signal end, the first stage of the sixth transistor is electrically connected with the grid electrode of the driving transistor, and the second stage of the sixth transistor is electrically connected with the second initialization signal end.
7. The pixel circuit of claim 1, wherein the storage circuit comprises a capacitor;
the first end of the capacitor is electrically connected with the reference voltage end, and the second end of the capacitor is electrically connected with the grid electrode of the driving transistor.
8. The pixel circuit according to claim 2, wherein the second initialization circuit includes a seventh transistor;
the grid electrode of the seventh transistor is electrically connected with the first scanning signal end, the first stage of the seventh transistor is electrically connected with the anode of the light emitting device, and the second stage of the seventh transistor is electrically connected with the second initialization signal end.
9. A display panel, comprising: a pixel circuit as claimed in any one of claims 1 to 8.
10. A driving method of a pixel circuit, which is applied to the pixel circuit according to any one of claims 1 to 8, wherein the pixel circuit includes a light emitting device, a driving transistor, a light emission control circuit, a write compensation circuit, a memory circuit, a reset circuit, and a first initialization circuit;
the driving method includes: a reset phase, a write compensation phase, a pre-light-emitting phase, and a light-emitting phase;
in the reset stage, the reset circuit responds to a reset signal to reset the grid electrode of the driving transistor;
in the writing compensation stage, the writing compensation circuit responds to a first scanning signal, writes a data signal into the driving transistor, and compensates the threshold voltage of the driving transistor;
in the pre-light emitting stage, the first initializing circuit responds to a second scanning signal and writes the first initializing signal into a second stage of the driving transistor;
in the light emitting stage, the light emission control circuit makes a first stage of the driving transistor turn on a voltage in response to a light emission control signal and supplies the driving current to the light emitting device;
wherein, in the time of one frame, the second scanning signal active level time is before the light emitting control signal active level time.
11. The method of claim 10, wherein the second scan signal active level time is subsequent to the first scan signal active level time.
12. The method of claim 10, wherein the pixel circuit further comprises a second initialization circuit, the method further comprising:
in the write compensation stage, the second initialization circuit writes a second initialization signal to an anode of the light emitting device in response to the first scan signal.
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| TWI560676B (en) * | 2015-12-07 | 2016-12-01 | Au Optronics Corp | Pixel circuit and driving method thereof |
| KR102561294B1 (en) * | 2016-07-01 | 2023-08-01 | 삼성디스플레이 주식회사 | Pixel and stage circuit and organic light emitting display device having the pixel and the stage circuit |
| CN106128360B (en) * | 2016-09-08 | 2018-11-13 | 京东方科技集团股份有限公司 | Pixel circuit, display panel, display equipment and driving method |
| CN111540315B (en) * | 2020-02-21 | 2024-03-15 | 福州京东方光电科技有限公司 | Pixel driving circuit, driving method thereof and display device |
| CN111383596A (en) * | 2020-03-25 | 2020-07-07 | 昆山国显光电有限公司 | Pixel circuit, display panel and driving method of pixel circuit |
| CN111613180A (en) * | 2020-05-18 | 2020-09-01 | 武汉华星光电半导体显示技术有限公司 | AMOLED pixel compensation driving circuit and method and display panel |
| CN112435630A (en) * | 2020-11-25 | 2021-03-02 | 京东方科技集团股份有限公司 | Pixel driving circuit, driving method and display panel |
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| CN103123774A (en) * | 2011-11-18 | 2013-05-29 | 乐金显示有限公司 | Organic light emitting diode display device |
| CN208335702U (en) * | 2018-05-14 | 2019-01-04 | 北京京东方技术开发有限公司 | Display panel and display device |
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