Patent Publication Number: US-11386862-B2

Title: Drive method, display panel and driving circuit

Description:
The present application claims priority to the Chinese Patent Application No. CN201910089130.X, filed with the Chinese Patent Office on Jan. 30, 2019, and entitled “DRIVING METHOD, DISPLAY PANEL AND DRIVING CIRCUIT”, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present application relates to the technical field of display, and in particular, to a driving method, a display panel and a driving circuit. 
     BACKGROUND 
     The statements herein merely provide background information related to the present application and do not necessarily constitute the prior art. 
     With the development and advancement of technologies, flat panel displays have become mainstream products of displays due to their thin bodies, power-saving and low radiation, and thus have been widely used. The flat panel displays include Thin Film Transistor-Liquid Crystal Displays (TFT-LCDs), Organic Light-Emitting Diode (OLED) displays, etc. The TFT-LCDs control the rotation direction of liquid crystal molecules to refract light of a backlight module to generate a picture, and has many advantages such as thin bodies, power-saving and no radiation. Moreover, the OLED displays are prepared by OLEDs, and have many advantages such as self-illumination, short response time, high definition and contrast, and can realize flexible display and large-area full-color display. 
     In the use of liquid crystal displays, the definition and stability of the display picture are an important problem that we&#39;ve been working on. The picture is often affected by the driving voltage, resulting in some flickers. Such a phenomenon has to be settled urgently. 
     SUMMARY 
     To achieve the foregoing objective, the present application provides a driving method, a display panel and a driving circuit capable of solving display picture flickers. 
     The present application further discloses a driving method applied to a display panel, the display panel including: a plurality of data lines, a plurality of gate lines, and a plurality of pixels; the gate lines are intersected with the data lines, the plurality of pixels is respectively driven by corresponding data lines and gate lines, and each of the plurality of pixels includes a corresponding pixel electrode; the driving method includes a step of outputting a gate driving signal to a corresponding gate line of the display panel; where a signal period of the gate driving signal includes a hold time, an open time, and a first pull-down time adjacent to the open time, the gate driving signal is in a first low level within the hold time, the gate driving signal is in a high level at the open time, the gate driving signal is in a second low level within the first pull-down time, and a voltage value of the second low level is lower than a voltage value of the first low level. 
     Optionally, the first pull-down time is before the open time, a signal period of the gate driving signal further includes a second pull-down time after the open time, the gate driving signal is in a third low level within the second pull-down time, and a voltage value of the third low level is lower than the voltage value of the first low level. 
     Optionally, the first pull-down time and the open time are equal in duration. 
     Optionally, the first pull-down time and the open time are equal in duration; and a gate driving signal of a current gate line corresponds to the first pull-down time when a gate driving signal of a previous gate line corresponds to the open time. 
     Optionally, the open time and the second pull-down time are equal in duration. 
     Optionally, the open time and the second pull-down time are equal in duration; and the gate driving signal of the current gate line corresponds to the open time when the gate driving signal of the previous gate line corresponds to the second pull-down time. 
     Optionally, the voltage value of the second low level is equal to the voltage value of the third low level. 
     Optionally, each pixel includes a pixel electrode, a same gate line is connected to two adjacent pixels to form a pixel group, and the pixel group includes a first pixel and a second pixel connected to different data lines. 
     Optionally, a pixel electrode of the first pixel of the pixel group overlaps with the previous gate line to form a first overlap region, the area of the first overlap region is S 1 , a storage capacitance formed by overlapping the first overlap region of the first pixel with the previous gate line is Cst 1 , a pixel capacitance of the first pixel is Clc 1 , and a parasitic capacitance formed by the pixel electrode of the first pixel and the current gate line is Cgs 1 ; the voltage values of the first low level and the third low level are V′GL, the voltage value of the high level is VGH, and the voltage value of the second low level is VGL; Cst 1 =(VGH−VGL)*Cgs 1 /(VGL−V′GL). 
     Optionally, a pixel electrode of the second pixel of the pixel group overlaps with a next gate line to form a second overlap region, the area of the second overlap region is S 2 , a storage capacitance formed by overlapping the second overlap region of the second pixel with the next gate line is Cst 2 , a pixel capacitance of the second pixel is Clc 2 , and a parasitic capacitance formed by the pixel electrode of the second pixel and the current gate line is Cgs 2 ; the voltage values of the first low level and the third low level are VGL, the voltage value of the high level is VGH, and the voltage value of the second low level is VGL; Cst 2 =(VGH−VGL)*Cgs 2 /(VGL−V′GL). 
     The present application further discloses a display panel using the driving method, where the display panel includes a plurality of data lines, a plurality of gate lines, and a plurality of pixels; the gate lines are intersected with the data lines, the plurality of pixels is respectively driven by corresponding data lines and gate lines, and each of the plurality of pixels includes a corresponding pixel electrode; a same gate line is connected to two adjacent pixels to form a pixel group, and the pixel group includes a first pixel and a second pixel connected to different data lines; where a pixel electrode of the first pixel of the pixel group overlaps with a previous gate line to form a first overlap region, and a pixel electrode of the second pixel of the pixel group overlaps with a next gate line to form a second overlap region. 
     Optionally, the gate lines include main gate lines and auxiliary gate lines conducted to each other, and the main gate lines are perpendicular to the auxiliary gate lines. 
     Optionally, the auxiliary gate lines include first auxiliary gate lines and second auxiliary gate lines, and the first auxiliary gate lines and the second auxiliary gate lines are arranged in parallel. 
     Optionally, the gate lines include main gate lines and auxiliary gate lines conducted to each other, the main gate lines are intersected with the data lines, and the auxiliary gate lines and the data lines are arranged in parallel. 
     Optionally, a first safety distance is arranged both between the auxiliary gate line and the corresponding pixel electrode of the first pixel of the current main gate line, and between the auxiliary gate line and the corresponding pixel electrode of the second pixel of the previous main gate line. 
     Optionally, a second safety distance is arranged between the auxiliary gate line and the corresponding data line. 
     Optionally, the first auxiliary gate line and the corresponding pixel electrode of the second pixel of the previous main gate line form a first overlap region, and the second auxiliary gate line and the corresponding pixel electrode of the first pixel of the next main gate line form a second overlap region. 
     Optionally, the area of the first overlap region is S 1 , and the area of the second overlap region is S 2 . 
     The present application further discloses a driving circuit for driving a display panel, and the driving circuit includes: a gate driving circuit configured to output a gate driving signal to a corresponding gate line of the display panel; where a signal period of the gate driving signal output by the gate driving circuit includes a hold time, an open time, and a first pull-down time adjacent to the open time, the gate driving signal is in a first low level within the hold time, the gate driving signal is in a high level at the open time, the gate driving signal is in a second low level within the first pull-down time, and a voltage value of the second low level is lower than a voltage value of the first low level. 
     Optionally, the first pull-down time is before the open time, a signal period of the gate driving signal further includes a second pull-down time after the open time, the gate driving signal is in a third low level within the second pull-down time, and a voltage value of the third low level is lower than the voltage value of the first low level. 
     Compared to the solution that the gate driving signal keeps a same level signal input in a period of time, in the present application, a period of each gate driving signal includes three time periods, respectively a hold time, an open time and a first pull-down time; the first pull-down time is adjacent to the open time; the gate driving signal is in a first low level within the hold time, in a high level at the open time, and in a second low level within the first pull-down time; due to the parasitic capacitance Cgs between the gate line and the pixel electrode, when elements are turned off after the pixels are charged, the change of the gate voltage redistributes a liquid crystal capacitance and storage capacitance charge of the pixels through the parasitic capacitance Cgs, so that a kickback phenomenon occurs to the voltage of the charged original pixels; the voltage value of the second low level within the first pull-down time is less than the voltage value of the first low level within the hold time; and the first pull-down time adjusts a kickback voltage generated by the parasitic capacitance generated between the pixel electrode and the gate line, so as to reduce or even eliminate the occurrence of flicker problems. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The drawings are included to provide further understanding of embodiments of the present application, which constitute a part of the specification and illustrate the embodiments of the present application, and describe the principles of the present application together with the text description. Apparently, the accompanying drawings in the following description show merely some embodiments of the present application, and a person of ordinary skill in the art may still derive other accompanying drawings from these accompanying drawings without creative efforts. In the accompanying drawings: 
         FIG. 1  is an enlarged schematic diagram of pixels of a display panel according to an embodiment of the present application; 
         FIG. 2  is a schematic diagram of a pixel structure circuit according to an embodiment of the present application; 
         FIG. 3  is a schematic diagram of a driving waveform having only one pull-down time according to an embodiment of the present application; 
         FIG. 4  is a schematic diagram of a driving waveform having two pull-down times according to an embodiment of the present application; 
         FIG. 5  is a schematic diagram of a driving waveform according to another embodiment of the present application; 
         FIG. 6  is a schematic diagram of a pixel structure according to another embodiment of the present application; 
         FIG. 7  is a schematic diagram of a driving circuit according to another embodiment of the present application; and 
         FIG. 8  is a schematic diagram of a display device according to another embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     It should be understood that the terms used herein and the specific structure and function details disclosed herein are merely representative, and are intended to describe specific embodiments. However, the present application can be specifically embodied in many alternative forms, and should not be interpreted to be limited to the embodiments described herein. 
     In the description of the present application, the terms such as “first” and “second” are merely for a descriptive purpose, and cannot be understood as indicating a relative importance, or implicitly indicating the number of the indicated technical features. Hence, the features defined by “first” and “second” can explicitly or implicitly include one or more features, and “a plurality of” means two or more, unless otherwise stated. The term “include” and any variations thereof are intended to cover a non-exclusive inclusion, and the presence or addition of one or more other features, integers, steps, operations, elements, components and/or combinations thereof may be possible. 
     In addition, orientation or position relationships indicated by the terms “center”, “transversal”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, etc. are based on the orientation or relative position relationships as shown in the drawings, for ease of the description of the present application and simplifying the description only, rather than indicating that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation. Therefore, these terms should not be understood as a limitation to the present application. 
     In addition, unless otherwise specified and defined, the terms “install”, “connected with”, “connected to” should be comprehended in a broad sense. For example, these terms may be comprehended as being fixedly connected, detachably connected or integrally connected; mechanically connected or electrically connected; or directly connected or indirectly connected through an intermediate medium, or in an internal communication between two elements. The specific meanings about the foregoing terms in the present application may be understood by a person of ordinary skill in the art according to specific circumstances. 
     The present application is further described below with reference to the accompanying drawings and optional embodiments. 
     With reference to  FIGS. 1-5 , this embodiment discloses a driving method applied to a display panel  110 . As shown in  FIG. 1 , the display panel  110  includes a plurality of data lines  130 , a plurality of gate lines  140 , and a plurality of pixels  150 ; the gate lines  130  are intersected with the data lines  140 , the plurality of pixels  150  is respectively driven by corresponding data lines  130  and gate lines  140 , and each of the plurality of pixels  150  includes a corresponding pixel electrode; 
     the driving method includes a step of outputting a gate driving signal to a corresponding gate line of the display panel  110 ; 
     where a signal period of the gate driving signal includes a hold time, an open time, and a first pull-down time adjacent to the open time; with reference to  FIG. 3 , the gate driving signal is in a first low level within the hold time, in a high level at the open time, and in a second low level within the first pull-down time, and the second low level is lower than the first low level. 
     In this solution, a period of each gate driving signal includes three time periods, respectively a hold time, an open time and a first pull-down time; the first pull-down time is adjacent to the open time; the gate driving signal is in a first low level within the hold time, in a high level at the open time, and in a second low level within the first pull-down time; with reference to  FIG. 2 , due to the parasitic capacitance Cgs between the gate line  140  and the pixel electrode, when elements are turned off after the pixels  150  are charged, the change of the gate voltage redistributes a liquid crystal capacitance and storage capacitance charge of the pixels through the parasitic capacitance Cgs, so that a kickback phenomenon occurs to the voltage of the charged original pixels  150 ; the voltage value of the second low level within the first pull-down time is less than the voltage value of the first low level within the hold time; and in order to lower the value of the kickback value, a kickback voltage generated by the parasitic capacitance generated between the pixel electrode and the gate line  140  is adjusted within the first pull-down time, so as to reduce or even eliminate the occurrence of flicker problems. 
     In an embodiment, with reference to  FIG. 4 , the first pull-down time is before the open time, a signal period of the gate driving signal further includes a second pull-down time after the open time, the gate driving signal is in a third low level within the second pull-down time, and a voltage value of the third low level is lower than the voltage value of the first low level. 
     In this solution, the parasitic capacitance redistributes a liquid crystal capacitance and storage capacitance charge of the pixels, so that a kickback phenomenon occurs to the voltage of the charged original pixels  150 ; the gate driving signal is a high level signal within the open time, and is a low level signal within the first pull-down time and the second pull-down time, and voltage values of the low levels are less than a voltage value of the low level within the hold time; and the low levels within two pull-down times are mainly for lowering the kickback voltage, so as to well solve or even eliminate the flicker problems of the display picture caused by the kickback voltage generated by the parasitic capacitance. 
     In an embodiment, the first pull-down time and the open time are equal in duration; and a gate driving signal of a current gate line  140  corresponds to the first pull-down time when a gate driving signal of a previous gate line  140  corresponds to the open time. 
     In this solution, the first pull-down time and the open time are equal in duration; a gate driving signal of a current gate line  140  exactly corresponds to the first pull-down time when a gate driving signal of a previous gate line  140  corresponds to the open time; if the durations are not equal, the correspondence cannot be achieved, causing confusion, and a correct loop cannot be formed, causing the display panel  110  to display abnormally. 
     In an embodiment, the open time and the second pull-down time are equal in duration; and the gate driving signal of the current gate line  140  corresponds to the open time when the gate driving signal of the previous gate line  140  corresponds to the second pull-down time. 
     In this solution, the gate driving signal of the current gate line  140  corresponds to the open time when the gate driving signal of the previous gate line  140  corresponds to the second pull-down time, to ensure that the open time and the second pull-down time are equal in duration, so as to achieve correspondence between the gate lines  140  to form the correct loop. 
     In an embodiment, the voltage value of the second low level is equal to the voltage value of the third low level. 
     In this solution, redistribution generated by the voltage of the parasitic capacitance causes a voltage kickback problem, influencing the picture; the voltage value of the second low level is equal to the voltage value of the third low level; the value of the second low level and the voltage value of the third low level can both adjust the kickback phenomenon to form a more accurate loop, so as to reduce or even eliminate the influence of kickback. 
     In an embodiment, each pixel  150  includes a pixel electrode, a same gate line  140  is connected to two adjacent pixels  150  to form a pixel group  160 , and the pixel group  160  includes a first pixel  161  and a second pixel  162  connected to different data lines  130 ; 
     where a pixel electrode of the first pixel  161  of the pixel group  160  overlaps with the previous gate line  140  to form a first overlap region  170 , a storage capacitance formed by overlapping the first overlap region  170  of the first pixel  161  with the previous gate line  140  is Cst 1 , a pixel capacitance of the first pixel  161  is Clc 1 , and a parasitic capacitance formed by the pixel electrode of the first pixel  161  and the current gate line is Cgs 1 ; 
     the voltage values of the first low level and the third low level are V′GL, the voltage value of the high level is VGH, and the voltage value of the second low level is VGL;
 
 Cst 1=( VGH−VGL )* Cgs 1/( VGL−VGL ).
 
     In this solution, with reference to  FIG. 4 , 
     At {circle around (1)}, Vpixel=Vdata 
     At {circle around (2)}, ΔV1=Δ′V+ΔV″ 1   
     ΔV′ 1 =(VGH−V′GL)*Cgs 1 /(Cgs+Cst+Clc) 
     ΔV″ 1 =(V′GL−VGH)*Cst 1 /(Cgs+Cst+Clc) 
     At {circle around (3)}, ΔV 2 =ΔV′ 2 +ΔV″ 2   
     ΔV′ 2 =(V′GL−VGL)*Cgs 1 /(Cgs+Cst+Clc) 
     ΔV″ 2 =(VGH−V′GL)*Cst 1 /(Cgs+Cst+Clc) 
     At {circle around (4)}, ΔV 3 =(VGL−VGL)*Cst 1 /(Cgs+Cst+Clc). 
     In order to reduce flickers caused by kickback, it is set that Cst 1 =(VGH−VGL)*Cgs 1 /(VGL−V′GL), to form a correct loop, eliminate the influence of the kickback voltage and avoid flickers. 
     In an embodiment, with reference to  FIG. 1 , each pixel  150  includes a pixel electrode, a same gate line  140  is connected to two adjacent pixels  150  to form a pixel group  160 , and the pixel group  160  includes a first pixel  161  and a second pixel  162  connected to different data lines  130 ; 
     with reference to  FIG. 6 , a pixel electrode of the second pixel  162  of the pixel group  160  overlaps with a next gate line  140  to form a second overlap region  180 ; 
     a storage capacitance formed by overlapping the second overlap region  180  of the second pixel  162  with the next gate line  140  is Cst 2 , a pixel capacitance of the second pixel  162  is Clc 2 , and a parasitic capacitance formed by the pixel electrode of the second pixel  162  and the current gate line is Cgs 2 ; 
     the voltage values of the first low level and the third low level are V′GL, the voltage value of the high level is VGH, and the voltage value of the second low level is VGL:
 
 Cst 2=( VGH−VGL )* Cgs 2/( VGL−V′GL ).
 
     In this solution, with reference to  FIG. 5 , 
     At {circle around (1)}, Vpixel=Vdata 
     At {circle around (2)}, ΔV 1 =ΔV′ 1 +ΔV″ 1   
     ΔV′ 1 =(VGH−V′GL)*Cgs 2 /(Cgs+Cst+Clc) 
     ΔV″ 1 =(V′GL−VGL)*Cst 2 /(Cgs+Cst+Clc) 
     At {circle around (3)}, ΔV 2 =(VGL−VGL)*Cgs 2 /(Cgs+Cst+Clc). 
     In order to reduce flickers caused by kickback, it is set that Cst 2 =(VGH−VGL)*Cgs 1 /(VGL−V′GL), to form a correct loop, eliminate the influence of the kickback voltage and avoid flickers. 
     As shown in  FIGS. 1 and 6 , as another embodiment of the present application, disclosed is a display panel  110  using the driving method. The display panel  110  includes a plurality of data lines  130 , a plurality of gate lines  140 , and a plurality of pixels  150 ; the gate lines  130  are intersected with the data lines  140 , the plurality of pixels  150  is respectively driven by corresponding data lines  130  and gate lines  140 , and each of the plurality of pixels  150  includes a corresponding pixel electrode; a same gate line  140  is connected to two adjacent pixels  150  to form a pixel group  160 , and the pixel group  160  includes a first pixel  161  and a second pixel  162  connected to different data lines  130 ; 
     where a pixel electrode of the first pixel  161  of the pixel group  160  overlaps with the previous gate line  140  to form a first overlap region  170 , and a pixel electrode of the second pixel  162  of the pixel group  160  overlaps with the next gate line  140  to form a second overlap region  180 . 
     In this solution, two pixels  150  in the pixel group  160  respectively correspond to different data lines  130 , so as to ensure the data driving voltage of each pixel  150  and prevent decrease of the data voltage caused by the load of the pixel electrode itself; in addition, the pixel electrodes of different pixels  150  in the pixel group  160  respectively overlap with the previous gate line  140  and the next gate line  140  to form two different storage capacitances; increasing the storage capacitance can reduce the influence of the parasitic capacitance generated by the pixel electrode and the gate line  140 , thereby reducing or even eliminating the flicker problem of the display panel  110  caused by the redistribution of the liquid crystal capacitance and the storage capacitance by the parasitic capacitance, and moreover, the aperture rate can be reduced, and the penetration rate of the liquid crystal molecules can be improved, so as to achieve large view-angle color offset. 
     In an embodiment, the gate lines  140  include main gate lines  141  and auxiliary gate lines  142  conducted to and perpendicular to each other, the auxiliary gate lines  142  include first auxiliary gate lines  1421  and second auxiliary gate lines  1422 , the first auxiliary gate line  1421  and the corresponding pixel electrode of the second pixel  162  of the previous main gate line  140  form a second overlap region  180 , and the second auxiliary gate line  1422  and the corresponding pixel electrode of the first pixel  161  of the next main gate line  140  form a first overlap region  170 ; a first safety distance is arranged both between the auxiliary gate line and the corresponding pixel electrode of the first pixel of the current main gate line, and between the auxiliary gate line and the corresponding pixel electrode of the second pixel of the previous main gate line; and a second safety distance is arranged between the auxiliary gate line and the corresponding data line. 
     In this solution, the auxiliary gate lines  142  extending from the main gate lines  141  and the pixel group  160  form an overlap region; the auxiliary gate lines  142  may have an effect of shielding an electric field; the first auxiliary gate lines and the second auxiliary gate lines are arranged in parallel to the data lines, and a safety distance is arranged, reducing the occurrence of the electric field between the pixel electrode and the data line  130 , and also preventing the pixel electrode and the main gate line  141  from generating a stronger parasitic capacitance. 
     As shown in  FIGS. 4 and 7 , as another embodiment of the present application, disclosed is a driving circuit. The driving circuit drives the display panel  110  as stated above, and includes: 
     a gate driving circuit  121  configured to output a gate driving signal to a corresponding gate line of the display panel  110 ; 
     where a signal period of the gate driving signal output by the gate driving circuit  121  includes a hold time, an open time, and a first pull-down time adjacent to the open time, the gate driving signal is in a first low level within the hold time, in a high level at the open time, and in a second low level within the first pull-down time, and a voltage value of the second low level is lower than a voltage value of the first low level. 
     In this solution, the driving circuit  120  is configured to drive the display panel  110 ; the gate driving circuit  121  in the driving circuit  120  outputs a signal to a corresponding gate line of the display panel  110 , and outputs a corresponding signal to turn on a corresponding gate line; a period of the gate driving signal is divided into three time periods for respectively outputting different levels; because of the influence of the kickback voltage caused by the parasitic capacitance generated by the pixel electrode and the gate line  140 , the voltage pull-down time is set for different time periods to form a correct loop so as to solve the flicker problem caused by the kickback voltage. 
     As shown in  FIG. 8 , as another embodiment of the present application, disclosed is a display device  100 , including the display panel  110  and a driving circuit  120 . 
     It should be noted that the definitions of steps involved in this solution are not intended to limit the sequence of steps without affecting the implementation of the specific solution. The preceding steps can be executed anteriorly, and can also be executed posteriorly, or even can be executed simultaneously. As long as this solution can be implemented, it should be considered as the scope of protection of the present application. 
     The technical solution of the present application can be widely applied to various display panels, such as a Twisted Nematic (TN) display panel, an In-Plane Switching (IPS) display panel, a Vertical Alignment (VA) display panel, and a Multi-domain Vertical Alignment (MVA) display panel, and certainly, may also be other types of display panels, such as an OLED display panel, if appropriate. 
     The contents above are detailed descriptions of the present application in conjunction with optional specific embodiments, and the specific implementation of the present application is not limited to these descriptions. It will be apparent to those skilled in the art that various simple deductions or substitutions may be made without departing from the spirit of the present application, and should be considered to be within the scope of protection of the present application.