CN117475864A - Display panel, driving method thereof and display device - Google Patents

Display panel, driving method thereof and display device Download PDF

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Publication number
CN117475864A
CN117475864A CN202210868957.2A CN202210868957A CN117475864A CN 117475864 A CN117475864 A CN 117475864A CN 202210868957 A CN202210868957 A CN 202210868957A CN 117475864 A CN117475864 A CN 117475864A
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China
Prior art keywords
push
pull signal
display
gray scale
display panel
Prior art date
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Pending
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CN202210868957.2A
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Chinese (zh)
Inventor
张东豪
张金刚
叶本银
黄亚东
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Chengdu Vistar Optoelectronics Co Ltd
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Chengdu Vistar Optoelectronics Co Ltd
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Priority to CN202210868957.2A priority Critical patent/CN117475864A/en
Publication of CN117475864A publication Critical patent/CN117475864A/en
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
    • 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
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0673—Adjustment of display parameters for control of gamma adjustment, e.g. selecting another gamma curve

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

Abstract

The invention discloses a display panel, a driving method thereof and a display device, wherein the display panel comprises a plurality of pixel circuits, the pixel circuits are correspondingly connected with a light-emitting element, and the pixel circuits are used for controlling the light-emitting time of the light-emitting element according to push-pull signals; the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the waveform curve of the push-pull signal. According to the technical scheme provided by the embodiment of the invention, the step length of the push-pull signal is smaller than the preset value, so that the adjustable brightness level of the display panel under the low gray level is increased, and the expansion of each gray level under the low gray level is facilitated. Compared with a linear push-pull signal, the waveform curve of the linear push-pull signal has more adjustable binding points in the same voltage drop, and gamma is favorably adjusted to meet the requirement of a target gamma curve, thereby being favorable for improving the display effect of the display panel.

Description

Display panel, driving method thereof and display device
Technical Field
The present invention relates to the field of display technologies, and in particular, to a display panel, a driving method thereof, and a display device.
Background
With the continuous development of display technology, light emitting diodes (light emitting diode, LEDs) are widely used in the display field by virtue of the advantages of wide color gamut, fast response speed, high brightness, long service life, and the like.
Currently, an LED display panel generally includes a pixel circuit and a light emitting element, and the pixel circuit is used to drive the light emitting element to emit light. However, in the display panel in the prior art, the gray scale cannot be fully developed in the display process, so that the display effect is affected.
Disclosure of Invention
The invention provides a display panel, a driving method thereof and a display device, which are used for improving the gray scale unfolding effect and facilitating the gamma adjustment of the display panel.
According to an aspect of the present invention, there is provided a display panel including a plurality of pixel circuits correspondingly connected to light emitting elements, the pixel circuits for controlling light emitting time of the light emitting elements according to push-pull signals;
the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the push-pull signal waveform curve.
Optionally, the step sizes of the push-pull signals corresponding to different gray scales are the same when the push-pull signals are displayed at the low gray scales.
Optionally, in the first display gray scale, the step length of the push-pull signal is a first step length, and in the second display gray scale, the step length of the push-pull signal is a second step length;
the first display gray scale is smaller than the second display gray scale, and the first step size is smaller than the second step size.
Optionally, the step size of the push-pull signal is smaller in the low gray scale display than in the high gray scale display.
Optionally, the gray scale of the low gray scale display includes 0-32 gray scales.
Optionally, the time intervals between two adjacent binding points on the push-pull signal waveform curve are the same; the time interval is the time when the push-pull signal changes once.
According to another aspect of the present invention, there is provided a driving method of a display panel including a plurality of pixel circuits correspondingly connected to light emitting elements;
the driving method of the display panel comprises the following steps:
controlling the on time of the pixel circuit according to the push-pull signal so as to control the light emitting time of the light emitting element; the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the push-pull signal waveform curve.
Optionally, the frame display of the display panel includes a low gray scale display and a high gray scale display, where the step sizes of the push-pull signals corresponding to the low gray scale display and the high gray scale display are different;
controlling the on time of the pixel circuit by the push-pull signal with a first step length in the low gray scale display;
controlling the on time of the pixel circuit by the push-pull signal with a second step length in the high gray scale display;
wherein the first step size is smaller than the second step size.
According to another aspect of the present invention, there is provided a display device including a display driving chip and a display panel provided by any embodiment of the present invention, where the display driving chip is connected to the display panel and is configured to output the push-pull signal.
Optionally, the display driving chip is used for performing gamma adjustment on the display device according to binding points on the push-pull signal waveform curve.
The technical scheme provided by the embodiment of the invention is that the waveform of the push-pull signal is curved, and the step length of the push-pull signal is smaller than a preset value at least in a low gray level display stage; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the waveform curve of the push-pull signal. Therefore, in the same time, the voltage variation amplitude of the push-pull signal sweet is smaller, so that the pulling of the grid potential of the driving transistor is smaller, the driving transistor is delayed to be turned on, the luminous duration of the luminous element is longer, the adjustable brightness level of the display panel is increased under the low gray scale, and the development of each gray scale under the low gray scale is facilitated. Compared with a linear push-pull signal, the waveform curve of the linear push-pull signal has more adjustable binding points in the same voltage drop, and gamma is favorably adjusted to meet the requirement of a target gamma curve, thereby being favorable for improving the display effect of the display panel.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a display panel according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a pixel circuit according to an embodiment of the present invention;
FIG. 3 is a waveform diagram of a push-pull signal according to an embodiment of the present invention;
FIG. 4 is a partial enlarged waveform diagram corresponding to the push-pull signal shown in FIG. 3;
FIG. 5 is a waveform diagram of a push-pull signal according to the prior art;
FIG. 6 is a waveform diagram of another push-pull signal 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 driving timing waveform diagram of a pixel circuit according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a display device according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As described in the background art, the existing display panel has a phenomenon that gray scales cannot be fully developed, so that the gray scales are discontinuous, thereby affecting gamma debugging of the display panel. The inventor researches and discovers that the reason why the above problem occurs is that the current display panel generally uses Micro-LEDs (Micro-Light Emitting Diode, micro-LEDs) as Light Emitting elements, and the Micro-LEDs are a new generation of display technology, and compared with the existing OLED (Organic Light-Emitting Diode) or LCD (Liquid Crystal Display) technology, the Micro-LEDs have the advantages of high resolution, high brightness, ultra-power saving, fast response speed, high Light Emitting efficiency, long service life and the like, and are widely applied to the display fields of mobile phones, notebook computers, televisions and the like. The light efficiency of the Micro-LED is greatly influenced by gray scale, and the light efficiency of the Micro-LED is rapidly reduced along with the reduction of the gray scale, so that the gray scale is discontinuous, the gamma curve cannot be effectively unfolded, the phenomenon that the gamma curve deviates from a target curve is caused, and the display brightness of a display panel is further influenced, and the display brightness is most obvious especially under the low gray scale. The relation between the display brightness and the gray scale of the display panel generally meets the curve relation of gamma 2.2, and when the gray scale cannot be fully unfolded, the gamma curve deviates from the target curve, which is not beneficial to gamma debugging.
In view of the above problems, embodiments of the present invention provide a display panel, a driving method thereof, and a display device, so as to improve the problem that low gray scale cannot be fully developed and optimize a gamma curve. Fig. 1 is a schematic structural diagram of a display panel according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of a pixel circuit according to an embodiment of the present invention, referring to fig. 1 and fig. 2, the display panel provided by the present embodiment includes a plurality of pixel circuits 100, the plurality of pixel circuits 100 are arranged in an array, and the pixel circuits 100 are correspondingly connected to a light emitting element D1, wherein the light emitting element D1 may be a Micro-LED or a Mini-LED.
The pixel circuit 100 may be driven in an analog-to-digital hybrid manner (i.e., PAM plus PWM driving mode), where the pixel circuit 100 includes a PWM driving module 1 and a PAM driving module 2, and the PWM driving module 1 is configured to convert an analog gray-scale voltage into a switching time for controlling the PAM driving module 2 to generate a driving current through PWM modulation. Illustratively, the PWM driving module 1 includes a driving transistor Q1, a data writing transistor Q2, a compensating transistor Q3, a light emission control transistor Q4, and a coupling module 11, wherein the coupling module 11 is configured to write a push-pull signal sweet to a gate of the driving transistor Q1 in a light emission phase, the coupling module 11 couples a gate voltage of the driving transistor Q1 in a process of changing the push-pull signal sweet, the gate voltage of the driving transistor Q1 changes with a change of the push-pull signal sweet, and when the gate voltage of the driving transistor Q1 is capable of making the driving transistor Q1 on, the first power voltage ELVDD is transmitted to the PAM driving module 2, so that the PAM driving module 2 is turned off, and the light emitting element D1 stops emitting, thereby achieving the purpose of controlling a light emission time of the light emitting element D1. The display brightness is determined by the change speed of the push-pull signal SWEEP, and the change speed of the push-pull signal SWEEP determines the light-emitting time, and the longer the light-emitting time is, the higher the display gray scale is, otherwise, the shorter the light-emitting time is, and the lower the display gray scale is.
Fig. 3 is a waveform diagram of a push-pull signal according to an embodiment of the present invention, referring to fig. 3, based on the above technical solution, a waveform of the push-pull signal sweet is curved, and at least in a low gray scale, a step Δv of the push-pull signal sweet is smaller than a preset value, where the preset value can be set according to actual requirements. Fig. 4 is a partial enlarged waveform diagram corresponding to the push-pull signal shown in fig. 3, and in combination with fig. 3 and 4, in this embodiment, a step Δv of the push-pull signal sweet refers to a voltage variation between two adjacent binding points on a waveform curve of the push-pull signal sweet. For example, when a display frame is 10 bits, the minimum time for changing the voltage value of the push-pull signal sweet is 1/1024s, and on the push-pull signal sweet waveform curve, the voltage value of the push-pull signal sweet corresponding to each time point is a binding point, and the time interval between two adjacent binding points on the push-pull signal sweet waveform curve is the same. The voltage drop of the push-pull signal SWEEP between two adjacent binding points is the step length DeltaV of the push-pull signal SWEEP. The step size Δv of the push-pull signal sweet is smaller than a preset value, that is, the variation amplitude of the push-pull signal sweet is smaller in the same time, so that the pull of the gate potential of the driving transistor Q1 is also smaller. Therefore, the driving transistor Q1 is turned on with a delay, so that the light emitting duration of the light emitting element D1 is longer, and the adjustable brightness level is increased at the low gray level, which is beneficial to the development of each gray level at the low gray level. And because the adjustable binding points of the push-pull signal SWEEP curve are increased, the technical scheme provided by the embodiment can reduce the bit number of the digital-to-analog conversion circuit under the condition of realizing the same number of binding points.
Fig. 5 is a waveform diagram of a push-pull signal in the prior art, and the number of adjustable binding points of the push-pull signal in the curvilinearity is greater than that of the linear push-pull signal in the prior art. Illustratively, at low gray scale, during the falling of the push-pull signal SWEEP from the voltage SWEEP-1 to SWEEP-2, the linear push-pull signal SWEEP has 4 binding points (corresponding to the straight line AB segments) for adjusting the gamma, and the linear push-pull signal SWEEP has 8 binding points (corresponding to the curve AC segments) for adjusting the gamma in FIG. 3. Therefore, after the number of gray scale expansion is increased, the number of corresponding adjustable binding points is also increased, so that the gamma curve of the display panel is more beneficial to being adjusted to a target curve, and the gamma debugging of the display panel is facilitated.
The technical scheme provided by the embodiment of the invention is that the waveform of the push-pull signal is curved, and the step length of the push-pull signal is smaller than a preset value at least in a low gray level display stage; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the waveform curve of the push-pull signal. Therefore, in the same time, the voltage variation amplitude of the push-pull signal sweet is smaller, so that the pulling of the grid potential of the driving transistor is smaller, the driving transistor is delayed to be turned on, the luminous duration of the luminous element is longer, the adjustable brightness level of the display panel is increased under the low gray scale, and the development of each gray scale under the low gray scale is facilitated. Compared with a linear push-pull signal, the waveform curve of the linear push-pull signal has more adjustable binding points in the same voltage drop, and gamma is favorably adjusted to meet the requirement of a target gamma curve, thereby being favorable for improving the display effect of the display panel.
Alternatively, the frame display of the display panel includes a low gray scale display and a high gray scale display, wherein the gray scale of the low gray scale display may be 0 to 32 gray scales and the gray scale of the high gray scale display may be 33 to 255 gray scales. Other gray scales are also possible in other embodiments. In low gray scale display, the step length delta V of push-pull signals SWEEP corresponding to different gray scales is the same, so that the change speed of the push-pull signals SWEEP is kept stable, the light emitting duration of the light emitting element D1 is increased, the gray scales can be continuously unfolded, the number of adjustable binding points can be increased, and the gamma curve is debugged. In the case of high gray scale display, the change of the display brightness is larger, and human eyes are insensitive to the change of the high gray scale, so that the gamma corresponding to the high gray scale is easier to debug, and therefore, the step length DeltaV of the push-pull signal SWEEP under the high gray scale display can be larger than the step length DeltaV of the push-pull signal SWEEP under the low gray scale display.
Illustratively, the display gray scale includes a first display gray scale and a second display gray scale, and the first display gray scale is smaller than the second display gray scale, e.g., the first display gray scale is 22 gray scales and the second display gray scale is 158 gray scales. The step length DeltaV of the push-pull signal SWEEP is a first step length at the first display gray level, and the step length DeltaV of the push-pull signal SWEEP is a second step length at the second display gray level, wherein the first step length is smaller than the second step length. Referring to fig. 3, at the first display gray level (e.g., may correspond to a point in the AD segment), the step size Δv of the push-pull signal sweet is smaller, so that the slope of the push-pull signal sweet at the display gray level is smaller, and the voltage variation of the push-pull signal sweet is smaller, so that the light emitting time of the light emitting element D1 is maintained longer, and the adjustable brightness level of the display panel is increased, thereby facilitating the adjustment of the gamma curve to the target curve. In the second display gray level (for example, a point in the DC section may be corresponding), the step Δv of the push-pull signal sweet is larger, so that the slope of the push-pull signal sweet in the display gray level is larger, and the voltage change of the push-pull signal sweet is larger, so that the light-emitting brightness change of the light-emitting element D1 is larger, and the characteristic of high gray level display is met.
Fig. 6 is a waveform diagram of another push-pull signal according to an embodiment of the present invention, referring to fig. 6, in this embodiment, the push-pull signal sweet may be a curve composed of multiple segments, and the step Δv of each segment is the same, that is, the voltage drop of the sweet signal is fixed in the same segment and within the same time. For example, in the segment AD segment, the voltage drop of the push-pull signal sweet is the same in the same period; in the DC section, the push-pull signal sweet drops the same voltage in the same period. And in the AD section and the DC section, the step size Δv of the push-pull signal sweet is different, whereby a curved waveform can be formed. For the pixel circuit shown in fig. 2, the display gray scale gradually increases as the push-pull signal green gradually decreases. Under low gray scale display, the step length DeltaV of the push-pull signal SWEEP is smaller, so that the push-pull signal SWEEP pulls the grid potential of the driving transistor less, the light emitting time under low gray scale is increased, the adjustable brightness level of the low gray scale is increased, and the adjustment of gamma is realized. In the high gray scale display, the step length Δv of the push-pull signal sweet can be increased appropriately to increase the pull amplitude of the push-pull signal sweet to the gate potential of the driving transistor, and the adjustment of gamma in the high gray scale is not affected.
Optionally, the waveform curve of the push-pull signal sweet may be a curve with a step length Δv changing at a moment, where the step length Δv corresponding to each gray level is different, but it is required to ensure that the step length Δv of the push-pull signal sweet in low gray level is smaller than a preset value, so as to ensure that the push-pull signal sweet in low gray level has more binding points to adjust gamma.
It should be noted that, according to different structures of the pixel circuits, the curve shape of the push-pull signal sweet may be changed according to actual requirements, so long as the waveform of the push-pull signal sweet is nonlinear, all the waveforms fall within the scope of the embodiments of the present invention.
Fig. 7 is a schematic structural diagram of another pixel circuit according to an embodiment of the present invention, referring to fig. 7, the pixel circuit includes a first driving transistor MD1 and a second driving transistor MD2, and the first switching transistor M1 is connected between a first initializing signal line and a gate G1 of the first driving transistor MD1, and is configured to transmit a first initializing voltage Vinit1 on the first initializing signal line to the gate G1 of the first driving transistor MD1 to initialize a gate potential of the first driving transistor MD 1. The second switching transistor M2 is connected between the second pole of the first driving transistor MD1 and the gate G1, the fifth switching transistor M5 is connected between the first data line and the first pole of the first driving transistor MD1, for writing the first data voltage vdata_t transmitted on the first data line to the gate G1 of the first driving transistor MD1 through the second switching transistor M2, the sixth switching transistor M6 is connected between the first power line and the first pole of the first driving transistor MD1, and the sixth switching transistor M6 is used for transmitting the first power voltage VDD on the first power line to the gate of the second driving transistor MD2 when the first driving transistor MD1 is turned on in the light emitting stage. The first capacitor C1 is a coupling capacitor for coupling the push-pull signal sweet to the gate G1 of the first driving transistor MD 1. The first capacitor C1, the first switching transistor M1, the second switching transistor M2, the third switching transistor M3, the fifth switching transistor M5, the sixth switching transistor M6 and the first driving transistor MD1 form a PWM driving module.
The fourth switching transistor M4 is connected between the first power line and the first pole of the second driving transistor MD2, the seventh switching transistor is connected between the second data line and the first pole of the second driving transistor MD2, the eighth switching transistor M8 is connected between the gate of the second driving transistor MD2 and the second pole, and the seventh switching transistor M7 is used for transmitting the second data voltage vdata_i on the second data line to the gate of the second driving transistor MD 2. The ninth switching transistor M9 is connected between the second initialization signal line and the gate electrode of the second driving transistor MD2, and is configured to transmit the second initialization voltage Vinit2 on the second initialization signal line to the gate electrode of the second driving transistor MD 2. The tenth switching transistor M10 is connected between the second electrode of the second driving transistor MD2 and the anode of the light emitting element, the cathode of which is connected to the second power line, where the light emitting element may be a light emitting diode LED, such as Micro-LED, mini-LED, etc. The second driving transistor MD2, the fourth switching transistor M4, the seventh switching transistor M7, the eighth switching transistor M8, the ninth switching transistor M9, and the tenth switching transistor M10 form a PAM driving module.
Fig. 8 is a driving timing waveform diagram of a pixel circuit according to an embodiment of the present invention, which is applicable to the pixel circuit shown in fig. 7, and is described with reference to fig. 7 and 8 by taking P-type transistors as all transistors as examples, the working process of the pixel circuit according to the embodiment of the present invention at least includes a voltage writing phase T1, a voltage normalizing phase T2 and a light emitting phase T3, wherein the voltage writing phase T1 includes a plurality of sub-phases.
In the first sub-stage t1 (corresponding to the initialization stage), the first scan signal line is configured to transmit the first scan signal S1 of a high level, the fourth scan signal line is configured to transmit the fourth scan signal S4 of a high level, the second scan signal line is configured to transmit the second scan signal S2 of a high level, the third scan signal line is configured to transmit the third scan signal S3 of a low level, the first light emission control signal line is configured to transmit the first light emission control signal EM1 of a high level, the second light emission control signal line is configured to transmit the second light emission control signal EM2 of a high level, the third light emission control signal line is configured to transmit the third light emission control signal EM3 of a high level, and the fourth light emission control signal line is configured to transmit the fourth light emission control signal EM4 of a high level. The ninth switching transistor M9 is turned on, and the remaining switching transistors are turned off, and the second initialization voltage Vinit2 transmitted on the second initialization signal line is written into the gate of the second driving transistor MD2, so as to initialize the gate potential of the second driving transistor MD 2.
In the second sub-stage t2 (corresponding to the second voltage writing stage), the first scan signal line is configured to transmit the first scan signal S1 of a low level, the fourth scan signal line is configured to transmit the fourth scan signal S4 of a low level, the second scan signal line is configured to transmit the second scan signal S2 of a high level, the third scan signal line is configured to transmit the third scan signal S3 of a high level, the first light emission control signal line is configured to transmit the first light emission control signal EM1 of a high level, the second light emission control signal line is configured to transmit the second light emission control signal EM2 of a high level, the third light emission control signal line is configured to transmit the third light emission control signal EM3 of a high level, and the fourth light emission control signal line is configured to transmit the fourth light emission control signal EM4 of a high level. The first, seventh and eighth switching transistors M1, M7 and M8 are turned on, the rest of the switching transistors are turned off, the second data voltage vdata_i is written into the gate of the second driving transistor MD2 through the seventh, second and eighth switching transistors M7, MD2 and M8, the gate potential of the second driving transistor MD2 is vdata_i+vth2, and is stored on the second capacitor C2, wherein Vth2 is the threshold voltage of the second driving transistor MD2, and the threshold compensation of the second driving transistor MD2 is achieved. Meanwhile, the first initialization voltage Vinit1 transmitted on the first initialization signal line is written into the gate G1 of the first driving transistor MD1 through the first switching transistor M1, thereby initializing the gate potential of the first driving transistor MD 1.
In the third sub-stage t3 (corresponding to the first voltage writing stage), the first scan signal line is configured to transmit the first scan signal S1 of a high level, the fourth scan signal line is configured to transmit the fourth scan signal S4 of a high level, the second scan signal line is configured to transmit the second scan signal S2 of a low level, the third scan signal line is configured to transmit the third scan signal S3 of a high level, the first light emission control signal line is configured to transmit the first light emission control signal EM1 of a high level, the second light emission control signal line is configured to transmit the second light emission control signal EM2 of a high level, the third light emission control signal line is configured to transmit the third light emission control signal EM3 of a high level, and the fourth light emission control signal line is configured to transmit the fourth light emission control signal EM4 of a high level. The second switching transistor M2 and the fifth switching transistor M5 are turned on, the first data voltage vdata_t charges the gate G1 of the first driving transistor MD1 until the gate voltage of the first driving transistor MD1 is vdata_t+vth1, vth1 is the threshold voltage of the first driving transistor MD1, the first driving transistor MD1 is turned off, and the gate potential of the first driving transistor MD1 is stabilized at vdata_t+vth1, thereby realizing threshold compensation for the first driving transistor MD 1. Meanwhile, the push-pull signal SWEEP is written into the first end of the first capacitor C1, and at this time, the voltage difference between two ends of the first capacitor C1 is data_t+Vt1-SWEEP.
In the fourth sub-stage t4, the first sub-stage t1, the second sub-stage t2 and the third sub-stage t3 are performed on the sub-pixels of the other rows row by row, and data writing of all pixel rows is completed.
In the voltage normalization stage T2, the push-pull signal sweet jumps to a high level sweet-H, coupling the gate potential of the first drive transistor MD 1. In the present embodiment, the high level sweet-H of the push-pull signal sweet is equal to or greater than the maximum value of the first data voltage vdata_t, so that the push-pull signal sweet can be written to the gate G1 of the first driving transistor MD 1. Here, since the fifth switching transistor M5 and the sixth switching transistor M6 are both turned off, there is no on-state capacitance between the gate G1 and the second pole of the first driving transistor MD1, the charge-discharge rate of the first driving transistor MD1 is not affected, and the accuracy of the gate voltage of the first driving transistor MD1 can be ensured.
In the light emission stage T3, the first scan signal line is configured to transmit the first scan signal S1 of a high level, the fourth scan signal line is configured to transmit the fourth scan signal S4 of a high level, the second scan signal line is configured to transmit the second scan signal S2 of a high level, the third scan signal line is configured to transmit the third scan signal S3 of a high level, the first light emission control signal line is configured to transmit the first light emission control signal EM1 of a low level, the second light emission control signal line is configured to transmit the second light emission control signal EM2 of a low level, the third light emission control signal line is configured to transmit the third light emission control signal EM3 of a low level, and the fourth light emission control signal line is configured to transmit the fourth light emission control signal EM4 of a low level. When the second and fourth light emission control signals EM2 and EM4 are at low levels, the fourth and tenth switching transistors M4 and M10 are turned on, and the second driving transistor MD2 generates a driving current according to the first power voltage VDD and the second data voltage vdata_i (stored in the second capacitor C2) to drive the light emitting diode LED to emit light. The drive current may be represented by the following formula:
where μ is electron mobility of the second driving transistor MD2, cox is channel capacitance per unit area of the second driving transistor MD2, W/L is width-to-length ratio of the second driving transistor MD2, and Vth2 is threshold voltage of the second driving transistor MD 2.
Meanwhile, the push-pull signal SWEEP gradually changes from the high level SWEEP-H to the low level SWEEP-L, and the gate potential of the first driving transistor MD1 synchronously changes due to the coupling effect of the first capacitor C1. When the push-pull signal sweet decreases such that the gate potential VG1 of the first driving transistor MD1 satisfies VG 1-vdd=vth1, the first driving transistor MD1 is turned on, and the first power voltage VDD is transmitted to the gate of the second driving transistor MD2 through the sixth switching transistor M6, the first driving transistor MD1 and the third switching transistor M3, controlling the second driving transistor MD2 to be turned off. Therefore, the first power line and the second power line are disconnected, the driving current is zero, the light emitting diode LED is turned off, and the control of the light emitting time is realized.
In this embodiment, the push-pull signal sweet is curved, and the step size Δv of the push-pull signal sweet is smaller when the push-pull signal sweet is displayed at a low gray level, and the specific working principle thereof may refer to the related description in the above technical scheme, which is not repeated herein.
In some embodiments, the second pole of the third switching transistor M3 may be further connected to the gate of the fourth switching transistor M4, and the lighting time is controlled by controlling the on-off of the fourth switching transistor M4, so that there is no direct signal control relationship between the PWE driving module and the PAM driving module, and the two share a part of the voltage signal, so as to simplify the external circuit.
Optionally, the embodiment of the invention further provides a driving method of the display panel. The driving method of the display panel comprises the following steps:
controlling the on time of the pixel circuit according to the push-pull signal so as to control the light emitting time of the light emitting element; the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the waveform curve of the push-pull signal.
The technical scheme provided by the embodiment of the invention is that the waveform of the push-pull signal is curved, and the step length of the push-pull signal is smaller than a preset value at least in a low gray level display stage; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the waveform curve of the push-pull signal. Therefore, in the same time, the voltage variation amplitude of the push-pull signal sweet is smaller, so that the pulling of the grid potential of the driving transistor is smaller, the driving transistor is delayed to be turned on, the luminous duration of the luminous element is longer, the adjustable brightness level of the display panel is increased under the low gray scale, and the development of each gray scale under the low gray scale is facilitated. Compared with a linear push-pull signal, the waveform curve of the linear push-pull signal has more adjustable binding points in the same voltage drop, and gamma is favorably adjusted to meet the requirement of a target gamma curve, thereby being favorable for improving the display effect of the display panel.
In this embodiment, the frame display of the display panel includes a low gray scale display and a high gray scale display, and the step sizes of push-pull signals corresponding to the low gray scale display and the high gray scale display are different.
In low gray scale display, controlling the on time of the pixel circuit by a push-pull signal with a first step length;
in the high gray scale display, the on time of the pixel circuit is controlled by a push-pull signal with a second step length; wherein the first step size is smaller than the second step size.
When the scanning frequency of the push-pull signal sweet is constant, the longer the light emitting time of the light emitting element is, the higher the display gray scale is. The gray scale is displayed to be gradually increased as the push-pull signal sweet is gradually decreased. Under low gray scale display, the step length DeltaV of the push-pull signal SWEEP is smaller, so that the push-pull signal SWEEP pulls the grid potential of the driving transistor less, the light emitting time under low gray scale is increased, the adjustable brightness level of the low gray scale is increased, and the gamma adjustment is realized. In the high gray scale display, the step size Δv of the push-pull signal sweet may be appropriately increased to increase the pull amplitude of the push-pull signal sweet to the gate potential of the driving transistor. Since the display brightness change under the high gray scale display is larger originally and human eyes are insensitive to the high gray scale change, the gamma corresponding to the high gray scale is easier to debug, and therefore the step length DeltaV of the push-pull signal SWEEP is properly increased, and the adjustment of the gamma under the high gray scale is not influenced.
Optionally, an embodiment of the present invention further provides a display device, where the display device includes a display driving chip and the display panel provided in any embodiment of the present invention, where the display driving chip is connected to the display panel and is used to output a push-pull signal sweet. Further, the display driving chip can perform gamma adjustment on the display device according to binding points on the push-pull signal SWEEP waveform curve. When the push-pull signal SWEEP is reduced from one voltage value to another voltage value, the more binding points on the push-pull signal SWEEP waveform curve are, the greater the probability of adjusting the gamma curve to the target curve is, and the gamma curve is favorably optimized. Fig. 9 is a schematic structural diagram of a display device according to an embodiment of the present invention, where the display device may be not only a mobile phone shown in fig. 9, but also a tablet, a mobile phone, a watch, a wearable device, and electronic devices such as a vehicle-mounted display, a camera display, a television, and a computer screen. The display device provided by the embodiment of the invention also has the beneficial effects described in any embodiment of the invention because the display device comprises the pixel circuit provided by any embodiment of the invention.
It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present invention may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present invention are achieved, and the present invention is not limited herein.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims (10)

1. The display panel is characterized by comprising a plurality of pixel circuits, wherein the pixel circuits are correspondingly connected with the light-emitting elements, and the pixel circuits are used for controlling the light-emitting time of the light-emitting elements according to push-pull signals;
the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the push-pull signal waveform curve.
2. The display panel according to claim 1, wherein the step sizes of the push-pull signals corresponding to different gray scales are the same when displaying at a low gray scale.
3. The display panel of claim 1, wherein the step size of the push-pull signal is a first step size at a first display gray level and a second step size at a second display gray level;
the first display gray scale is smaller than the second display gray scale, and the first step size is smaller than the second step size.
4. The display panel of claim 1, wherein the push-pull signal has a step size at a low gray scale display that is smaller than a step size at a high gray scale display.
5. The display panel of any one of claims 1-4, wherein a time interval between two adjacent binding points on the push-pull signal waveform curve is the same.
6. The display panel of claim 5, wherein the time interval is a time when the push-pull signal changes once.
7. The driving method of the display panel is characterized in that the display panel comprises a plurality of pixel circuits which are correspondingly connected with the light-emitting elements;
the driving method of the display panel comprises the following steps:
controlling the on time of the pixel circuit according to the push-pull signal so as to control the light emitting time of the light emitting element; the waveform of the push-pull signal is in a curve shape and is displayed at least at low gray level, and the step length of the push-pull signal is smaller than a preset value; the step length of the push-pull signal is the voltage variation between two adjacent binding points on the push-pull signal waveform curve.
8. The method according to claim 7, wherein the frame display of the display panel includes a low gray scale display and a high gray scale display, and wherein the step sizes of the push-pull signals corresponding to the low gray scale display and the high gray scale display are different;
controlling the on time of the pixel circuit by the push-pull signal with a first step length in the low gray scale display;
controlling the on time of the pixel circuit by the push-pull signal with a second step length in the high gray scale display;
wherein the first step size is smaller than the second step size.
9. A display device comprising a display driver chip and the display panel of any one of claims 1-6, the display driver chip being connected to the display panel for outputting the push-pull signal.
10. The display device of claim 9, wherein the display driver chip is configured to perform gamma adjustment on the display device according to binding points on the push-pull signal waveform curve.
CN202210868957.2A 2022-07-22 2022-07-22 Display panel, driving method thereof and display device Pending CN117475864A (en)

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