CN109036315B - Driving method and driving device of display panel and display equipment - Google Patents

Driving method and driving device of display panel and display equipment Download PDF

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Publication number
CN109036315B
CN109036315B CN201811041044.3A CN201811041044A CN109036315B CN 109036315 B CN109036315 B CN 109036315B CN 201811041044 A CN201811041044 A CN 201811041044A CN 109036315 B CN109036315 B CN 109036315B
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voltage
pixel
common
thin film
film transistor
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CN109036315A (en
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赵攀
林汇哲
胡伟
黄式强
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BOE Technology Group Co Ltd
Chongqing BOE Optoelectronics Technology Co Ltd
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BOE Technology Group Co Ltd
Chongqing BOE Optoelectronics Technology Co Ltd
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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
    • G09G3/34—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 by control of light from an independent source
    • G09G3/36—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 by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3696—Generation of voltages supplied to electrode drivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

Abstract

The invention discloses a driving method and a driving device of a display panel and display equipment, and belongs to the field of liquid crystal display devices. The driving method of the display panel comprises the steps of providing data signals to pixel electrodes of pixel units to enable the pixel electrodes to generate pixel voltages; the common voltage signal is used for enabling the common electrode to generate common voltage changing along with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value of the pixel voltage and the common voltage in the same display stage is not more than a preset value, so that the variation degree of the light transmittance of the liquid crystal in the display stage is kept in a certain range, and the variation degree of the displayed brightness is also kept in a certain range, and therefore when the same frame of picture is displayed, the brightness variation of the pixel unit can be reduced.

Description

Driving method and driving device of display panel and display equipment
Technical Field
The present invention relates to the field of liquid crystal display devices, and in particular, to a driving method and a driving device for a display panel, and a display apparatus.
Background
In the display process of the liquid crystal display panel, an electric field is generated between the pixel electrode and the common electrode to drive liquid crystal molecules to deflect, the deflected liquid crystal molecules can transmit light with certain brightness, and the light transmittance of the liquid crystal molecules is changed by adjusting the electric field intensity between the pixel electrode and the common electrode, so that different gray scale display is realized.
In the driving process, the common voltage on the common electrode is always kept constant, the absolute value of the difference value between the pixel voltage and the common voltage corresponds to the displayed gray scale, and when the absolute value of the difference value between the pixel voltage and the common voltage is different, the light transmittance of the liquid crystal is also different, so that the displayed gray scale is also different.
In the process of displaying the same frame of picture, the pixel voltage on the pixel electrode is not constant, so that the difference value between the pixel voltage and the common voltage is not constant, and the light transmittance of the liquid crystal is changed, so that the displayed gray scale is changed, and the display is visually represented as that the brightness of the same frame of picture is changed.
Disclosure of Invention
The embodiment of the invention provides a driving method and a driving device of a display panel and display equipment, which can reduce the brightness change of the same frame of picture. The technical scheme is as follows:
in one aspect, an embodiment of the present invention provides a method for driving a display panel, including:
providing a data signal to a pixel electrode of a pixel unit to enable the pixel electrode to generate a pixel voltage;
and providing a common voltage signal to a common electrode corresponding to the pixel electrode, wherein the common voltage signal is used for enabling the common electrode to generate a common voltage which changes along with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage does not exceed a preset value.
Optionally, the display panel includes a plurality of pixel units, each pixel unit includes the pixel electrode and the common electrode, the common electrode and the pixel electrode are disposed in a one-to-one correspondence, and the method further includes:
and generating the common voltage signal corresponding to the gray scale to be displayed according to the gray scale to be displayed by the pixel unit.
Optionally, the generating the common voltage signal corresponding to a gray scale to be displayed according to a gray scale to be displayed by the pixel unit includes:
determining a voltage value set corresponding to the gray scale to be displayed according to a corresponding relation between the pre-stored gray scale and the voltage value set, wherein each voltage value set comprises a plurality of voltage values;
and generating the common voltage signal based on the plurality of voltage values, wherein the common voltage signal comprises a plurality of sub-signals which sequentially last for a preset time length, and the voltages of the plurality of sub-signals are respectively equal to the corresponding voltage values in the plurality of voltage values.
Optionally, the method further comprises:
respectively acquiring a plurality of pixel voltages corresponding to different gray scales;
determining a difference between the pixel voltage and the common voltage during the display phase;
obtaining the common voltage signals corresponding to different gray scales according to the difference value and the pixel voltage so as to obtain the corresponding relation between the gray scales and the voltage value set;
and storing the corresponding relation between the gray scale and the voltage value set.
Optionally, in the display phase displaying the same gray scale, the absolute value of the difference between the pixel voltage and the common voltage is equal.
On the other hand, an embodiment of the present invention further provides a driving apparatus for a display panel, including:
the controller is used for providing data signals to the pixel electrodes of the pixel units so that the pixel electrodes generate pixel voltages; and the common voltage signal is used for enabling the common electrode to generate a common voltage which changes with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage does not exceed a preset value.
Optionally, the display panel includes a plurality of pixel units, each pixel unit includes the pixel electrode and the common electrode, the common electrodes are disposed in one-to-one correspondence with the pixel electrodes, and the controller is further configured to generate the common voltage signal corresponding to a gray scale to be displayed according to a gray scale to be displayed by the pixel unit.
Optionally, the method further comprises:
the memory is used for storing the corresponding relation between the gray scale and the voltage value set;
the controller is further configured to determine a voltage value set corresponding to a gray scale to be displayed according to a pre-stored correspondence relationship between the gray scale and the voltage value set, where each voltage value set includes a plurality of voltage values, and generate the common voltage signal based on the plurality of voltage values, where the common voltage signal includes a plurality of sub-signals that sequentially last for a preset time duration, and voltages of the plurality of sub-signals are respectively equal to corresponding voltage values in the plurality of voltage values.
In still another aspect, the embodiment of the present invention further provides a display device, which includes the driving apparatus of the display panel as described above.
Optionally, the display device further includes a display panel, the display panel includes a plurality of common electrode lines, a plurality of data lines, and a plurality of scan lines, the plurality of common electrode lines and the plurality of data lines are alternately distributed at intervals, the plurality of data lines and the plurality of scan lines intersect with each other to define a plurality of pixel regions, each of the pixel regions has a pixel unit disposed therein, the pixel unit includes a common electrode, a pixel electrode, a first thin film transistor, and a second thin film transistor,
in the same pixel unit, the pixel electrode is connected to a first pole of the first thin film transistor, a second pole of the first thin film transistor is connected to the corresponding data line, a control pole of the first thin film transistor is connected to the corresponding scan line,
in the same pixel unit, the common electrode is connected to a first pole of the second thin film transistor, a second pole of the second thin film transistor is connected to the corresponding common electrode line, and a control pole of the second thin film transistor is connected to the corresponding scan line.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least: in the display stage of the pixel, the pixel voltage can change gradually along with time, the common electrode generates common voltage changing along with the pixel voltage by providing a common voltage signal to the common electrode in the display stage of the pixel, and the variation of the difference value of the pixel voltage and the common voltage in the same display stage is not more than a preset value, so that the variation degree of the light transmittance of the liquid crystal in the display stage is kept in a certain range, and the variation degree of the displayed brightness is also kept in a certain range, thereby reducing the brightness variation of the pixel unit when the same frame of picture is displayed.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a partial structure of a display panel;
FIG. 2 is a diagram of driving timing signals of a pixel circuit;
fig. 3 is a flowchart of a driving method of a display panel according to an embodiment of the present invention;
FIG. 4 is a diagram of driving timing signals of a pixel circuit according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating the relationship between a common voltage signal and a common voltage according to an embodiment of the present invention;
FIG. 6 is a flowchart of a method for obtaining correspondence between gray scale values and voltage value sets according to an embodiment of the present invention;
FIG. 7 is a simplified diagram of driving timing signals according to an embodiment of the present invention;
fig. 8 is a structural diagram of a driving apparatus of a display panel according to an embodiment of the present invention;
fig. 9 is a schematic partial circuit diagram of a display device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic partial structure diagram of a display panel. As shown in fig. 1, the display panel includes a common electrode line, a plurality of scan lines 11, and a plurality of data lines 12. A plurality of scanning lines 11 and a plurality of data lines 12 cross each other to define a plurality of pixel regions E, each of which has a pixel unit disposed therein. The pixel unit includes a thin film transistor T and a pixel electrode 13Some of the pixel electrodes 13 correspond to a common electrode 14 in common. A thin film transistor T is connected to the intersection of the scanning line 11 and the data line 12. A first electrode of the thin film transistor T is connected to the data line 12, a control electrode of the thin film transistor T is connected to the scan line 11, and a second electrode of the thin film transistor T is connected to the pixel electrode 13 and the storage capacitor CstAnd (4) connecting. The first pole of the thin film transistor T and the second pole of the thin film transistor T are one of a source electrode and a drain electrode of the thin film transistor T, respectively. The common electrode 14 is disposed in parallel with the pixel electrode 13 at a distance, and liquid crystal is interposed between the pixel electrode 13 and the common electrode 14. The common electrode 14 and the common electrode line may be connected by a via hole. The scan lines 11 are used for loading scan signals, the data lines 12 are used for loading data signals, and both the scan signals and the data signals can be square wave signals. When the thin film transistor T is turned on by a scan signal, a data signal is applied to the data line 12, and a pixel voltage is formed on the pixel electrode 13.
Fig. 2 is a driving timing signal diagram of a pixel circuit. Taking a pixel unit as an example, V in FIG. 2gFor scanning signals, VpIs the pixel voltage, VcomIs a common voltage, t1In order to charge the pixel unit, the thin film transistor T is in the charging stage T1Is conducted to the storage capacitor CstAnd (6) charging. t is t2In the display stage of the pixel unit, the thin film transistor T is in the display stage T2Is turned off to stop the storage capacitor CstAnd (6) charging. Charging phase t1Is much shorter than the display period t2The length of time. In a display phase t2And when all the pixel units of the display panel traverse once, the display panel realizes the display of one frame of picture. As shown in fig. 2, during the charging phase t1Storage capacitor CstIn the charging process, the voltage of the pixel electrode 13 rises, and an electric field is established between the pixel electrode 13 and the common electrode 14. In a display phase t2Storage capacitor CstThe charging is stopped, the voltage of the pixel electrode 13 stops rising, and a constant electric field is formed between the pixel electrode 13 and the common electrode 14. Liquid crystal is between the pixel electrode 13 and the common electrode 14Is deflected under the action of the electric field, and the light transmittance of the liquid crystal changes. By changing the voltage difference between the pixel electrode 13 and the common electrode 14, the light transmittance of the liquid crystal can be changed, thereby realizing gray scale display. In a display phase t2The voltage of the pixel electrode 13 is generally considered to be constant (as shown in fig. 2 for a period t)2Indicated by the horizontal dashed line). In practice, however, the off-state current I of the TFT T is usedoffIn the display phase t2The voltage of the pixel electrode gradually changes. As shown in fig. 2, during the whole display phase t2Pixel voltage changes by Voff. Therefore, the electric field formed between the pixel electrode 13 and the common electrode 14 is not constant, and the light transmittance of the liquid crystal is not constant during the display period t2Gradually changing, and displaying the same frame of picture will have brightness change. The technical scheme provided by the embodiment of the invention aims to reduce the brightness change of the same frame of picture caused by the reason.
Fig. 3 is a flowchart of a driving method of a display panel according to an embodiment of the present invention. As shown in fig. 3, the driving method of the display panel includes:
s11: and providing a data signal to the pixel electrode of the pixel unit to enable the pixel electrode to generate a pixel voltage.
S12: and generating a common voltage signal corresponding to the gray scale to be displayed according to the gray scale to be displayed by the pixel unit.
And a common voltage signal is loaded on the common electrode through the common electrode line, so that the common electrode generates a common voltage. When different gray scales are displayed, different data signals are loaded on the data lines, so that different pixel voltages are generated by the pixel electrodes, and therefore, the pixel voltages have a corresponding relation with the displayed gray scales, and the pixel voltages can be determined according to the gray scales to be displayed. As can be seen from fig. 2, the pixel voltage changes in the display phase, and the different pixel voltages also change in the display phase, so that the variation of the difference between the pixel voltage and the common voltage does not exceed the predetermined value in the same display phase, the common voltage needs to be set corresponding to the pixel voltage. Therefore, the corresponding public voltage signal can be generated according to the gray scale to be displayed, so that the public electrode can generate the corresponding public voltage.
S13: a common voltage signal is supplied to a common electrode corresponding to the pixel electrode.
The common voltage signal is used for enabling the common electrode to generate common voltage changing along with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value of the pixel voltage and the common voltage in the same display stage does not exceed a preset value.
During the display stage of the pixel unit, the pixel voltage can change gradually along with time, the common electrode generates common voltage changing along with the pixel voltage by providing a common voltage signal to the common electrode during the display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage is not more than a preset value, so that the variation degree of the light transmittance of the liquid crystal in the display stage is kept in a certain range, and the variation degree of the displayed brightness is also kept in a certain range, thereby reducing the brightness change of the pixel unit when the same frame of picture is displayed.
Step S12 is an optional step, and for some display panels, such as the liquid crystal display of calculator, car audio, electronic scale, water heater, electronic watch, etc., no gray scale display is required, i.e., the pixel unit only displays one brightness in the display stage, and step S12 may not be provided. The structure of such a display panel may be the same as that of the display panel shown in fig. 1. In such a display panel, all the pixel electrodes correspond to the same common electrode.
Except for a small part of display panels, most display panels need to be subjected to gray scale display, such as liquid crystal display screens of mobile phones, tablet computers and the like. In order to reduce the brightness variation of such a display panel when displaying the same frame of picture, step S12 may be provided. The display panel comprises a plurality of pixel units, each pixel unit comprises a pixel electrode and a common electrode which are arranged in a one-to-one correspondence mode, namely a plurality of common electrodes are arranged, and the common electrodes and the pixel electrodes are arranged in a one-to-one correspondence mode. The structure of the display panel can be seen in fig. 9. In the display stage, the variation of the difference value between the pixel voltage on the pixel electrode and the common voltage on the corresponding common electrode does not exceed a preset value, so that the brightness variation of each pixel unit when the same frame of picture is displayed can be reduced.
Alternatively, the preset value may be 0, and when the preset value is 0, that is, the difference between the pixel voltage and the common voltage is constant in the same display phase. This can completely eliminate the brightness variation of the pixel unit when the same frame of picture is displayed. The present embodiment takes the default value of 0 as an example for explanation.
Fig. 4 is a driving timing signal diagram of a pixel circuit according to an embodiment of the invention. As shown in fig. 4, the scanning signal VgPixel voltage VpAll as in fig. 2, charging phase t1Display stage t2Also the same as in fig. 2. The common voltage in fig. 4 is indicated by a dotted line for distinction, while the common voltage in fig. 2 is also shown in fig. 4 for comparison. In a display phase t2Pixel voltage VpAnd a common voltage VcomThe difference value of (a) is always constant, so that in this stage, the electric field formed between the pixel electrode 13 and the common electrode 14 is kept constant, the light transmittance of the liquid crystal is constant, and no brightness change occurs in the same frame.
Alternatively, the absolute values of the differences between the pixel voltages and the common voltage may be equal in the display stage displaying the same gray scale. In different display stages, as long as the displayed gray scales are the same, the absolute value of the difference value between the pixel voltage and the common voltage is equal, so that when the gray scales of two adjacent frames are the same, flicker can not occur when the two frames are displayed. In order to prevent the liquid crystal from being always deflected in one direction and polarized, it is generally necessary to perform polarity inversion. Taking fig. 4 as an example, when displaying a frame of picture, each pixel unit only goes through one display period t2Two adjacent display phases t of one pixel cell are shown2Thus, the two-frame picture display can be realized. The pixel voltage on the pixel electrode 13 at the previous frame is larger than the common voltage on the common electrode 14, and is driven with positive polarity at this time. The pixel voltage of the pixel electrode 13 at the time of the next frame is smaller than the common voltage on the common electrode 14, and is driven in the negative polarity at this time. If the gray scales to be displayed in the two frames are the sameBefore and after the polarity inversion, the absolute value of the difference between the pixel voltage and the common voltage is not equal, and the flicker occurs. The absolute value of the difference value between the pixel voltage and the common voltage in the two frames is equal, and the light transmittance of the liquid crystal is also the same, so that the gray scales displayed by the two frames are the same, and the picture flicker can not occur. Therefore, the requirement of polarity inversion can be met, the liquid crystal display device can normally display, and flicker can be avoided in the polarity inversion process.
Optionally, before step S12, a voltage value set corresponding to the gray scale to be displayed may be determined according to a pre-stored correspondence relationship between the gray scale and the voltage value set, where each voltage value set includes a plurality of voltage values. A common voltage signal is then generated based on the plurality of voltage values.
Alternatively, the common voltage signal may include a plurality of sub-signals sequentially lasting for a preset time period, and voltages of the plurality of sub-signals are respectively equal to corresponding voltage values of a plurality of voltage values of the voltage value set. For example, the number of voltage values in the set of voltage values and the number of sub-signals may be equal, and the voltages of the plurality of sub-signals sequentially vary according to the voltage values in the set of voltage values. Alternatively, the number of voltage values in the set of voltage values may be larger than the number of sub-signals, in which case, the same number of voltage values as the number of sub-signals may be selected from the set of voltage values in a set order, and then the voltages of several sub-signals are sequentially changed according to the selected voltage values. For example, the voltage value set includes 12 voltage values, and the number of the sub-signals is 6, in this case, 6 voltage values may be selected at intervals from the 12 voltage values, such as selecting an odd-numbered voltage value or selecting an even-numbered voltage value.
Fig. 5 is a schematic diagram of a relationship between a common voltage signal and a common voltage according to an embodiment of the present invention. Two common voltage signals a and B and common voltages a and B corresponding to the common voltage signals a and B, common voltage signals C and D, and common voltages C and D corresponding to the common voltage signals C and D are shown in fig. 5. As shown in fig. 5, the common voltage signal is synchronized with the common voltage. Different gray levels correspond to different common voltage signals, which may generate different common voltages on the common electrode. The common voltage signal a shown in fig. 5 includes 6 sub-signals sequentially lasting for a preset time period. The shorter the preset time period is, the more the number of sub-signals included in the common voltage signal is, the closer the waveform of the common voltage signal is to the curve, and the smaller the variation of the difference value between the pixel voltage and the common voltage in the same display period is, the closer the difference value is to constant, for example, the common voltage signal C and the common voltage signal D.
Before step S11, the common electrode driving method may further include acquiring and storing a correspondence relationship between gray scales and voltage value sets. The common voltage signal can be conveniently generated after acquiring and storing the corresponding relation between the gray scale and the voltage value set.
Fig. 6 is a flowchart of a method for obtaining correspondence between gray scale values and voltage value sets according to an embodiment of the present invention. The method can acquire the corresponding relation between the gray scale and the voltage value set through one pixel unit. As shown in fig. 6, the method includes:
s21: and respectively acquiring various pixel voltages corresponding to different gray scales.
Alternatively, step S21 may include the steps of:
the method comprises the following steps: and in the same display stage, pixel voltage values at a plurality of moments are acquired.
In the display stage, the pixel voltage changes along with time, and the change relation of the pixel voltage along with time in the display stage is obtained by obtaining the pixel voltage values at a plurality of moments, so that the public voltage is convenient to determine.
For example, the pixel voltage value of the display device that has been manufactured may be acquired by measurement. The pixel voltage values may be acquired at equal time intervals. For example, a scanning signal is loaded on a scanning line, a data signal is loaded on a data line, a pixel voltage is generated on a pixel electrode, a waveform of the pixel voltage changing along with time can be obtained through an oscilloscope, and pixel voltage values at different moments can be obtained from the waveform.
Alternatively, the same data signal may be loaded on the data line multiple times, multiple waveforms may be acquired by the oscilloscope, multiple pixel voltage values may be obtained at fixed time intervals from each waveform, and an average value of the pixel voltage values at the same time of different waveforms may be calculated. Therefore, the relation between the pixel voltage and the time can be obtained according to the average value in the subsequent step, and the result is more accurate. For example, when the pixel voltage corresponding to the gray scale 200 is obtained, the data signal corresponding to the gray scale 200 may be loaded on the data line 10 times, so that 10 pixel voltages corresponding to the gray scale 200 may be obtained, and an oscilloscope may obtain 10 similar waveforms (there is a certain difference between waveforms due to an error). Taking the display stage of each pixel voltage in the positive polarity driving as an example, each pixel voltage respectively obtains 6 pixel voltage values, 6 average values can be obtained by averaging, and the relationship between the pixel voltage and the time can be obtained according to the 6 average values in the subsequent steps.
Referring to fig. 4, during a charging phase t1At the end, the voltage on the pixel electrode is V1In the display phase t2At the beginning, the TFT is turned off due to the voltage drop of the scan line, which causes a Δ V to appear in the voltage on the pixel electrodepTo make the voltage on the pixel electrode drop to V2，ΔVp＝Cgs*ΔVg/(Clc+Cst+Cgs) In which C isgsΔ V is the parasitic capacitance between the first and control electrodes of the thin film transistorgIs a reduced value of the voltage on the scanning line, ClcA capacitor of liquid crystal, CstIs the capacitance of the storage capacitor. In the measurement, the display period t can be measured2Pixel voltage value V at starting time2Then measuring a plurality of pixel voltage values at equal time intervals, e.g. from the display phase t2Starting from the initial time, measuring 5-10 pixel voltage values at intervals, and assuming a display stage t2If 5 pixel voltage values are measured at intervals lasting 1ms, one pixel voltage value can be measured every 0.25 ms.
Step two: and obtaining the relation between the pixel voltage and the time according to the pixel voltage values at a plurality of moments.
The relation between the pixel voltage and the time refers to the relation between the pixel voltage and the time in the same display stageAnd (4) relationship. In the same display phase, the pixel voltage is gradually changed, taking the first display phase shown in fig. 4 as an example, the pixel voltage is gradually decreased, and the relationship between the pixel voltage and the time can be obtained by obtaining the pixel voltage values at a plurality of times. For example, after obtaining a plurality of pixel voltage values, a functional relation V of the pixel voltage and the time is fittedpF (t), where t is time. The more pixel voltage values obtained in step one, the more accurate the obtained relationship between the pixel voltage and the time.
The voltage on the pixel electrode is different for different gray scales, so that the relationship between the pixel voltage and the time corresponding to the different gray scales can be obtained by respectively measuring the different gray scales. For example, a typical display device has 256 gray levels, and thus 256 pixel voltages versus time can be obtained.
Further, in consideration of the polarity inversion of the liquid crystal display device, the pixel voltages are different in the negative polarity driving and the positive polarity driving, and therefore, for the same gray scale, the pixel voltage and the time relationship in the negative polarity driving and the pixel voltage and the time relationship in the positive polarity driving can be obtained by performing measurement in the negative polarity driving and the positive polarity driving, respectively.
S22: the difference between the pixel voltage and the common voltage during the display phase is determined.
Wherein the difference is constant during the same voltage holding phase.
In different gray scales, the absolute values of the difference values between the pixel voltage and the common voltage are different, so that different difference values can be set corresponding to different gray scales. The absolute value of the difference between the negative polarity driving and the positive polarity driving is the same for the same gray scale. For example, in a certain gray scale, the difference value in the positive polarity driving may be set to Δ V, and the difference value in the negative polarity driving may be set to- Δ V.
S23: and obtaining common voltage signals corresponding to different gray scales according to the difference values and the pixel voltages so as to obtain the corresponding relation between the gray scales and the voltage value set.
Due to the difference between the pixel voltage and the common voltage at any time in the same display stageThe values are all equal, so that the difference is subtracted from the pixel voltage to obtain the common voltage at the corresponding moment. For example, in the positive polarity driving, display period t2At the beginning, the common voltage Vcom＝V2- Δ V. If after obtaining a plurality of pixel voltage values, fitting a functional relation of the pixel voltage and the time as VpF (t), then the common voltage VcomF (t) - Δ V. If the driving is performed with negative polarity, the common voltage V is setcomF (t) + Δ V. If the display device has 256 gray levels, resulting in 256 pixel voltages versus time, 256 common voltages can be determined. For a display panel which does not require gray scale display, the relationship between 1 pixel voltage and time can be obtained in each of negative polarity driving and positive polarity driving.
In the positive polarity drive and negative polarity drive of the same gray scale, the display stage t2The common voltages at the beginning may not be equal or may be equal. For example, the driving timing signal diagram shown in FIG. 7, in which only the display period t is shown2The pixel voltage and the common voltage. In a first display phase t2At the beginning, the pixel voltage is V2Common voltage Vcom＝V2Δ V in the second display phase t2At the beginning, the pixel voltage is V2', common voltage Vcom＝V2' + Δ V, in two display phases t2Common voltage V at the beginningcomAre all equal, thus in the display phase t2At the beginning, the common voltage Vcom＝0.5(V2+V2’)。
Since the common voltage signal is synchronous with the common voltage, the common voltage signals corresponding to different gray scales can be obtained after the common voltage is obtained. For example, a plurality of voltage values of the common voltage corresponding to any gray scale are acquired at equal time intervals, and the voltage values constitute a voltage value set corresponding to the gray scale, so that a correspondence relationship between the gray scale and the voltage value set can be obtained.
Fig. 8 is a structural diagram of a driving apparatus of a display panel according to an embodiment of the present invention. As shown in fig. 8, the driving device includes a controller 31.
The controller 31 is configured to provide a data signal to the pixel electrode, so that the pixel electrode generates a pixel voltage; and is used to provide a common voltage signal to the common electrode. The common voltage signal is used for enabling the common electrode to generate common voltage changing along with the pixel voltage in the display stage of the pixel unit, and the variation of the difference value of the pixel voltage and the common voltage in the same display stage does not exceed a preset value.
The controller 31 may provide the common voltage signal to the common electrode according to the aforementioned step S13.
During the display stage of the pixel unit, the pixel voltage can change gradually along with time, the common electrode generates common voltage changing along with the pixel voltage by providing a common voltage signal to the common electrode during the display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage is not more than a preset value, so that the variation degree of the light transmittance of the liquid crystal in the display stage is kept in a certain range, and the variation degree of the displayed brightness is also kept in a certain range, thereby reducing the brightness change of the pixel unit when the same frame of picture is displayed.
Alternatively, the preset value may be 0, and when the preset value is 0, that is, the difference between the pixel voltage and the common voltage is constant in the same display phase. This can completely eliminate the brightness variation of the pixel unit when the same frame of picture is displayed.
Optionally, the controller 31 may be further configured to generate a common voltage signal corresponding to a gray scale to be displayed according to a gray scale to be displayed by the pixel unit. The controller 31 may generate the common voltage signal according to the aforementioned step S12. When the display panel comprises a plurality of pixel units, each pixel unit comprises a pixel electrode and a common electrode which are arranged in a one-to-one correspondence mode, namely a plurality of common electrodes are arranged, and the common electrodes and the pixel electrodes are arranged in a one-to-one correspondence mode, the driving device can reduce the brightness change of each pixel unit when the same frame of picture is displayed.
Further, the driving apparatus may further include a memory 32, and the memory 32 is used for storing a corresponding relationship between gray scale and voltage value sets. The generation of the common voltage signal can be facilitated. The correspondence between the gray scale and the voltage value sets can be obtained according to the method shown in fig. 6.
The controller 31 may be further configured to determine a voltage value set corresponding to a gray scale to be displayed according to a correspondence relationship between a pre-stored gray scale and the voltage value set, where each voltage value set includes a plurality of voltage values, and generate a common voltage signal based on the plurality of voltage values, where the common voltage signal includes a plurality of sub-signals that sequentially last for a preset time duration, and voltages of the plurality of sub-signals respectively correspond to voltage values of the plurality of voltage values of the voltage value set. The controller 31 may generate the common voltage signal according to the aforementioned method embodiments.
Embodiments of the present invention also provide a display device, which may include a driving apparatus of a display panel as shown in fig. 8. Alternatively, the display device may be, but is not limited to, a liquid crystal display device such as a mobile phone, a tablet computer, a navigator, and the like.
Fig. 9 is a schematic partial circuit diagram of a display device according to an embodiment of the present invention. As shown in fig. 9, the display device further includes a display panel including a plurality of common electrode lines 16, a plurality of data lines 12, and a plurality of scan lines 11. The plurality of common electrode lines 16, the plurality of data lines 12, and the plurality of scanning lines 11 are connected to a driving device 17 of the display panel.
The plurality of common electrode lines 16 and the plurality of data lines 12 are alternately spaced apart, and the plurality of data lines 12 and the plurality of scan lines 11 cross each other to define a plurality of pixel regions E. Each pixel region E is provided with a pixel unit, and the pixel unit includes a common electrode 14, a pixel electrode 13, a first thin film transistor T1, and a second thin film transistor T2, and only a partial structure of the common electrode 14 and the pixel electrode 13 is schematically shown in the figure. In the same pixel unit, the pixel electrode 13 is connected to the first electrode of the first thin film transistor T1, the second electrode of the first thin film transistor T1 is connected to the corresponding data line 12, and the control electrode of the first thin film transistor T1 is connected to the corresponding scan line 11. In the same pixel unit, the common electrode 14 is connected to the first electrode of the second thin film transistor T2, the second electrode of the second thin film transistor T2 is line-connected to the corresponding common electrode 14, and the control electrode of the second thin film transistor T2 is connected to the corresponding scan line 11. A liquid crystal is sandwiched between the pixel electrode 13 and the common electrode 14. A first pole of the first thin film transistor T1 and a second pole of the first thin film transistor T1 are one of a source and a drain of the first thin film transistor T1, respectively. A first pole of the second thin film transistor T2 and a second pole of the second thin film transistor T2 are one of a source and a drain of the second thin film transistor T2, respectively. The on-off of the first thin film transistor T1 and the second thin film transistor T2 can be controlled simultaneously by the scan lines, and different common voltage signals can be loaded by the plurality of common electrode lines 16, so that different common voltages can be generated on different common electrodes 14. Thus, different voltage differences can be generated between the pixel electrode 13 and the common electrode 14 in different pixel units to control the deflection of the liquid crystal, so that different gray scales can be displayed. In the display stage, the variation of the difference between the pixel voltage on each pixel electrode 13 and the common voltage on the corresponding common electrode 14 does not exceed a preset value, so that the brightness variation of each pixel unit when the same frame of picture is displayed can be reduced.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. A driving method of a display panel is characterized in that the display panel comprises a plurality of pixel units, the pixel units of the display panel comprise a common electrode, a pixel electrode, a first thin film transistor and a second thin film transistor, in the same pixel unit, the pixel electrode is connected with a first pole of the first thin film transistor, a second pole of the first thin film transistor is connected with a data line, the common electrode is connected with a first pole of the second thin film transistor, a second pole of the second thin film transistor is connected with the common electrode line, a control pole of the first thin film transistor and a control pole of the second thin film transistor are connected with the same scanning line,
the driving method includes:
providing a data signal to a pixel electrode of a pixel unit to enable the pixel electrode to generate a pixel voltage;
determining a voltage value set corresponding to the gray scale to be displayed according to a corresponding relation between the pre-stored gray scale and the voltage value set, wherein each voltage value set comprises a plurality of voltage values;
generating the common voltage signal based on the plurality of voltage values, wherein the common voltage signal includes a plurality of sub-signals which sequentially last for a preset time duration, voltages of the plurality of sub-signals are respectively equal to corresponding voltage values in the plurality of voltage values, the number of voltage values in the voltage value set is greater than or equal to the number of the sub-signals, voltages of the plurality of sub-signals sequentially change according to the voltage values in the voltage value set, and if the number of voltage values in the voltage value set is greater than the number of the sub-signals, voltages of the plurality of sub-signals sequentially change according to voltage values which are selected from the voltage value set and have the same number as the number of the sub-signals according to a set sequence;
and providing a common voltage signal to a common electrode corresponding to the pixel electrode, wherein the common voltage signal is used for enabling the common electrode to generate a common voltage which changes along with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage does not exceed a preset value.
2. The method for driving a display panel according to claim 1, further comprising:
respectively acquiring a plurality of pixel voltages corresponding to different gray scales;
determining a difference between the pixel voltage and the common voltage during the display phase;
obtaining the common voltage signals corresponding to different gray scales according to the difference value and the pixel voltage so as to obtain the corresponding relation between the gray scales and the voltage value set;
and storing the corresponding relation between the gray scale and the voltage value set.
3. The method according to claim 2, wherein in the display period in which the same gray scale is displayed, the absolute value of the difference between the pixel voltage and the common voltage is equal.
4. A driving device of a display panel is characterized in that the display panel comprises a plurality of pixel units, each pixel unit of the display panel comprises a common electrode, a pixel electrode, a first thin film transistor and a second thin film transistor, in the same pixel unit, the pixel electrode is connected with a first pole of the first thin film transistor, a second pole of the first thin film transistor is connected with a data line, the common electrode is connected with a first pole of the second thin film transistor, a second pole of the second thin film transistor is connected with the common electrode line, a control pole of the first thin film transistor and a control pole of the second thin film transistor are connected with the same scanning line,
the driving device includes:
the controller is used for providing data signals to the pixel electrodes of the pixel units so that the pixel electrodes generate pixel voltages; the common voltage signal is used for enabling the common electrode to generate common voltage which changes along with the pixel voltage in a display stage of the pixel unit, and the variation of the difference value between the pixel voltage and the common voltage in the same display stage does not exceed a preset value;
the memory is used for storing the corresponding relation between the gray scale and the voltage value set;
the controller is also used for determining a voltage value set corresponding to the gray scale to be displayed according to the pre-stored corresponding relation between the gray scale and the voltage value set, each voltage value set comprises a plurality of voltage values, and generating the common voltage signal based on the plurality of voltage values, the common voltage signal including a plurality of sub-signals sequentially lasting for a preset time period, the voltages of the number of sub-signals are respectively equal to corresponding ones of the plurality of voltage values, the number of voltage values in the set of voltage values being greater than or equal to the number of sub-signals, the voltages of the plurality of sub-signals sequentially change according to the voltage values in the voltage value set, if the number of the voltage values in the voltage value set is larger than the number of the sub-signals, the voltages of the plurality of sub-signals sequentially change according to the voltage value set, the voltage values which are selected according to the set sequence and have the same number with the sub signals are changed in sequence.
5. A display device characterized in that it comprises driving means of a display panel as claimed in claim 4.
6. The display device according to claim 5, further comprising a display panel including a plurality of common electrode lines, a plurality of data lines, and a plurality of scan lines, the plurality of common electrode lines and the plurality of data lines being alternately spaced apart, the plurality of data lines and the plurality of scan lines crossing each other to define a plurality of pixel regions, each of the pixel regions having a pixel unit disposed therein, the pixel unit including a common electrode, a pixel electrode, a first thin film transistor, and a second thin film transistor,
in the same pixel unit, the pixel electrode is connected to a first pole of the first thin film transistor, a second pole of the first thin film transistor is connected to the corresponding data line, a control pole of the first thin film transistor is connected to the corresponding scan line,
in the same pixel unit, the common electrode is connected to a first pole of the second thin film transistor, a second pole of the second thin film transistor is connected to the corresponding common electrode line, and a control pole of the second thin film transistor is connected to the corresponding scan line.
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