KR20080099410A - Liquid crystal display device and driving method thereof - Google Patents

Liquid crystal display device and driving method thereof Download PDF

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Publication number
KR20080099410A
KR20080099410A KR1020070044916A KR20070044916A KR20080099410A KR 20080099410 A KR20080099410 A KR 20080099410A KR 1020070044916 A KR1020070044916 A KR 1020070044916A KR 20070044916 A KR20070044916 A KR 20070044916A KR 20080099410 A KR20080099410 A KR 20080099410A
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KR
South Korea
Prior art keywords
liquid crystal
gate
high voltage
crystal cells
crystal display
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Application number
KR1020070044916A
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Korean (ko)
Inventor
김화영
이상훈
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엘지디스플레이 주식회사
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Priority to KR1020070044916A priority Critical patent/KR20080099410A/en
Publication of KR20080099410A publication Critical patent/KR20080099410A/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
    • G09G3/34—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
    • G09G3/3674—Details of drivers for scan electrodes
    • G09G3/3677—Details of drivers for scan electrodes suitable for active matrices only
    • 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
    • G09G3/3685—Details of drivers for data electrodes
    • G09G3/3688—Details of drivers for data electrodes suitable for active matrices only
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F1/163—Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
    • G02F2001/1635—Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor the pixel comprises active switching elements, e.g. TFT
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0823—Several active elements per pixel in active matrix panels used to establish symmetry in driving, e.g. with polarity inversion
    • 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
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes

Abstract

A liquid crystal display device capable of improving image quality deterioration is disclosed.

A liquid crystal display device according to the present invention includes a liquid crystal display panel, a data driver for alternately supplying positive and negative pixel data voltages to at least two liquid crystal cells in a vertical direction of the liquid crystal display panel, and a pixel output from the data driver. A gate voltage generator configured to generate a gate high voltage or a gate low voltage to turn on or off the thin film transistors of the liquid crystal cells to charge the data voltages into the liquid crystal cells by one line, and a gate generated from the gate voltage generator A gate voltage modulator that modulates a high voltage and a gate high voltage are driven in the preceding liquid crystal cells among the liquid crystal cells that are adjacent in the vertical direction and have the same polarity, and a modulated gate high voltage is used in the subsequent liquid crystal cells. Including a gate driver to drive by The.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY DEVICE AND DRIVING METHOD THEREOF}

1 is a block diagram showing a vertical two-dot inversion liquid crystal display device according to an embodiment of the present invention.

2A and 2B illustrate a vertical two-dot inversion scheme according to an embodiment of the present invention.

3 is a view illustrating an interior of a gate driver of FIG. 1.

4 is a waveform diagram illustrating a gate high voltage and a modulated gate high voltage of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 5 is a diagram illustrating a pixel data voltage charged for each line in the liquid crystal display panel of FIG. 1.

6 is a block diagram showing a liquid crystal display device according to another embodiment of the present invention.

7 is a waveform diagram illustrating a gate high voltage and a modulated gate high voltage of a liquid crystal display according to another exemplary embodiment of the present invention.

<Explanation of symbols for main part>

110, 210: LCD panel 120, 220: data driver

130, 230: gate driver 140: timing controller

150: gate voltage generator 160: gate voltage modulator

211: driving thin film transistor 213: precharging thin film transistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device and a driving method thereof capable of improving image quality deterioration.

The LCD displays an image by adjusting light transmittance of liquid crystal cells according to a video signal. In an active matrix type liquid crystal display, switching elements are formed in each liquid crystal cell, which is advantageous for displaying moving images. As a switching device, a thin film transistor (TFT) is mainly used.

In order to drive a liquid crystal cell of a liquid crystal display panel, a liquid crystal display device uses a frame inversion method, a line inversion method, a column inversion method, and a dot inversion method. Inversion driving methods such as Inversion Method are used.

In the frame inversion type liquid crystal display device, the polarity of the video signal input to the liquid crystal display panel is reversed whenever the frame is changed. However, the frame inversion method has a problem in that flicker occurs in units of frames.

In the line inversion type liquid crystal display, the polarity of the video signal is inverted for each gate line and frame of the liquid crystal display panel. However, the line inversion method has a problem that flicker, such as a stripe pattern, occurs between vertical lines due to the presence of crosstalk between pixels in the horizontal direction.

In the column inversion type liquid crystal display, the polarity of the video signal is inverted for each data line and frame on the liquid crystal display panel. However, the column inversion scheme has a problem in that flicker such as a stripe pattern occurs between vertical lines as crosstalk is transmitted between vertical pixels.

One dot inversion method of the dot inversion method allows the liquid crystal cells adjacent to each other in the horizontal and vertical directions to be supplied with a video signal of opposite polarity to each of the liquid crystal cells, and the polarity of the video signal is inverted for each frame.

The two-dot inversion method of the dot inversion method allows a video signal having a polarity opposite to that of all adjacent liquid crystal cells in a horizontal and vertical direction in two line units, and the polarity of the video signal is inverted every frame. The two-dot inversion method has the same polarity with respect to two liquid crystal cells adjacent in the horizontal direction, and two liquid crystal cells adjacent to the two liquid crystal cells in the horizontal direction have opposite polarities.

In the above-described driving method, the two-dot inversion method allows flickers generated between frames to cancel each other, thereby providing an image having excellent image quality compared to other inversion methods.

Among the driving methods described above, the two-dot inversion method includes a horizontal two-dot inversion method in which polarities are inverted in every two liquid crystal cells in a horizontal direction, and a vertical two-dot inversion method in which polarities are inverted in every two liquid crystal cells in a vertical direction. It includes.

In the vertical two-dot inversion scheme, since the liquid crystal cells adjacent in the vertical direction sequentially charge pixel voltages of the same polarity sequentially, an unbalanced voltage is generated. In fact, the second liquid crystal cell adjacent to the first liquid crystal cell rather than the first liquid crystal cell which first charges the positive (or negative) data voltage charges the positive (or negative) data voltage for a long time. do.

For example, when two liquid crystal cells adjacent in the vertical direction sequentially charge pixel data voltages having the same voltage level, the voltage charged in the second liquid crystal cell becomes higher than the voltage charged in the first liquid crystal cell. As a result, streaks appear in the image, as well as deterioration in image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display and a driving method thereof suitable for preventing deterioration of image quality.

Liquid crystal display device according to an embodiment of the present invention for achieving the above object,

A liquid crystal display panel;

A data driver configured to alternately supply positive and negative pixel data voltages to at least two liquid crystal cells in a vertical direction of the liquid crystal display panel;

A gate voltage generator configured to generate a gate high voltage or a gate low voltage to turn on or off the thin film transistors of the liquid crystal cells in order to charge the pixel data voltage output from the data driver into liquid crystal cells for one line;

A gate voltage modulator for modulating the gate high voltage generated from the gate voltage generator; And

Among the liquid crystal cells adjacent to each other in the vertical direction and having the same polarity, the previous liquid crystal cells are driven by using the gate high voltage, and the subsequent liquid crystal cells include a gate driver that is driven by using the modulated gate high voltage. .

In addition, the driving method of the liquid crystal display device of the present invention,

Supplying positive and negative pixel data voltages alternately in at least two liquid crystal cells in a vertical direction in a liquid crystal display panel;

Generating a gate high voltage for turning on the thin film transistor of the liquid crystal display panel;

Generating the gate high voltage using the gate high voltage; And

And supplying the gate high voltage to the preceding liquid crystal cells among the liquid crystal cells adjacent to each other in the vertical direction and having the same polarity, and supplying the modulated gate high voltage to the subsequent liquid crystal cells.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a liquid crystal display device of a vertical 2-dot inversion method according to an embodiment of the present invention.

As shown in FIG. 1, a vertical two-dot inversion liquid crystal display device according to an exemplary embodiment of the present invention includes a liquid crystal display panel 110 in which liquid crystal cells are arranged in a matrix, and the liquid crystal display panel 110. A gate driver 130 for driving the gate lines GL1 to GLn of the gate, a data driver 120 for driving the data lines DL1 to DLm of the liquid crystal display panel 110, and the gate driver ( 130 and a timing controller 140 for controlling the data driver 120.

The liquid crystal display panel 110 is formed at each intersection of the liquid crystal cells arranged in a mattress shape, the gate lines GL1 to GLn, and the data lines DL1 to DLm, and is connected to the liquid crystal cells, respectively. TFT: thin film transistor).

The thin film transistor TFT is turned on when the scan signals from the gate lines GL1 to GLn, that is, the gate high voltage VGH is supplied, to convert the pixel data voltages from the data lines DL1 to DLm to the liquid crystal cell. To feed. The thin film transistor TFT is turned off when the gate low voltage VGL is supplied from the gate lines GL1 to GLn to maintain the pixel data voltage charged in the liquid crystal cell.

The liquid crystal cell is equivalently represented by a liquid crystal capacitor Clc, and includes a common electrode facing the liquid crystal and a pixel electrode connected to the thin film transistor TFT. The liquid crystal cell further includes a storage capacitor Cst to stably maintain the charged pixel signal until the next pixel signal is charged. The storage capacitor Cst is formed between the pixel electrode and the front gate line. The liquid crystal cell realizes gray scale by adjusting light transmittance by changing an arrangement state of liquid crystal having dielectric anisotropy according to pixel data voltage charged through a thin film transistor (TFT).

The data driver 120 may output the pixel data signals data R, G, and B for one line per horizontal period in response to the data control signals SSP, SSC, SOE, and POL from the timing controller 140. To DL1 to DLm. In particular, the data driver 120 converts the digital pixel data signal from the timing controller 140 into an analog pixel data signal using a gamma voltage from a gamma voltage generator (not shown) to convert the data lines DL1 to DLm. To supply.

In detail, the data driver 120 shifts the source start pulse SSP according to the source shift clock SSC to generate a sampling signal. Subsequently, the data driver 120 sequentially inputs and latches the pixel data signal in predetermined units in response to the sampling signal.

The data driver 120 converts a digital pixel data signal of one line among the latched pixel data signals into an analog pixel data signal and supplies the same to the data lines DL1 through DLm. The data driver 120 converts the pixel data signals R, G, and B into positive and negative pixel data signals in response to the polarity control signal POL.

For example, the polarity of the pixel data signal alternates the positive and negative polarities of one or more liquid crystal cells in the horizontal direction, and the positive and negative polarities of two or more liquid crystal cells in the vertical direction.

In the present invention, with reference to FIG. 2A, the pixel data signals of the positive and negative polarities are alternated for each liquid crystal cell in the horizontal direction, and the pixel data signals of the positive and negative polarities are alternated for each of the two liquid crystal cells in the vertical direction. Referring to FIG. 2B, a vertical two-dot inversion scheme in which all liquid crystal cells are inverted per frame will be described as an embodiment.

The liquid crystal display of the present invention further includes a gate voltage modulator 150 for modulating the gate high voltage VGH.

The gate voltage modulator 160 modulates the gate high voltage VGH generated by the gate voltage generator 150 to charge the pixel data voltage charged in a subsequent liquid crystal cell among liquid crystal cells having the same polarity in the vertical direction. It delays time or controls the amount of charge of the pixel data voltage being charged.

The gate driver 130 sequentially gates a high voltage VGH or a modulated gate high voltage to the gate lines GL1 to GLn in response to the gate control signals GSP, GSC, and GOE from the timing controller 140. Supply (VGM). Accordingly, the gate driver 130 causes the thin film transistor TFT connected to the gate lines GL1 to GLn to be turned on in the gate line unit.

The gate driver 130 sequentially supplies the gate low voltage VGL to the gate lines GL1 to GLn in response to the gate control signals GSP, GSC, and GOE from the timing controller 140. Accordingly, the gate driver 130 causes the thin film transistor TFT connected in the gate lines GL1 to GLn to be turned off in units of gate lines.

Specifically, the gate driver 130 shifts the gate start pulse GSP according to the gate shift pulse GSC to generate a shift pulse. The gate driver 130 selects the gate high voltage VGH or the modulated gate high voltage VGHM in response to the shift pulse, so that the gate high voltage VGH or the modulated gate high voltage (VGH) or the modulated gate high voltage is applied to the corresponding gate line every horizontal section. VGHM).

Here, the gate high voltage VGH and the gate low voltage VGL are generated from the gate voltage generator 150.

The gate voltage modulator 160 modulates the gate high voltage VGH generated by the gate voltage generator 150 to turn on the thin film transistor TFT of even-numbered liquid crystal cells. ) That is, the modulated gate high voltage VGHM turns on the thin film transistors TFTs connected to the even-numbered gate lines GL2 to GLn.

The liquid crystal display according to the exemplary embodiment includes a gate voltage modulator 160 to transfer the thin film transistors TFTs corresponding to the odd gate lines GL1 to GLn-1 to the gate high voltage VGH. The thin film transistors TFTs corresponding to even-numbered gate lines GL2 to GLn are turned on by the modulated gate high voltage VGHM.

According to the present invention, the modulated gate high voltage VGHM of the liquid crystal display panel 110 is used to charge pixel data voltages corresponding to subsequent liquid crystal cells among liquid crystal cells not only adjacent to each other in the vertical direction but having the same polarity. The amount of charge can be adjusted.

Therefore, the vertical 2-dot inversion type liquid crystal display device according to the exemplary embodiment of the present invention can improve the image quality defect of the stripe phenomenon due to the unbalanced charging time of the pixel data voltage between the liquid crystal cells having the same polarity in the vertical direction. .

3 is a view illustrating the inside of the gate driver of FIG. 1, FIG. 4 is a waveform diagram illustrating a gate high voltage and a modulated gate high voltage of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. FIG. 1 is a diagram illustrating pixel data voltages charged line by line in the liquid crystal display panel of FIG. 1.

As shown in FIG. 3, the gate driver of the liquid crystal display according to the exemplary embodiment includes a plurality of channels for outputting a driving signal. That is, it includes a shift register (not shown) including a shift stage 131 as many as the number of gate lines, and a buffer 133 connected to the shift stage 131, respectively. It can be seen that the shift stages 131 are connected in series with each other.

For example, the i-th shift stage 131 and the i-th buffer 133 are connected to the i-th gate line GLi.

The i-th shift stage 131 is enabled from a time point at which the previous i-1 th shift stage is disabled by a gate control signal, and outputs an enable signal to the i-th buffer 133. .

The i th buffer 133 is gated to an i th gate line GLi connected to the i th buffer 133 by gate control signals GSC and GOE when the i th gate line GLi is an odd number. The high voltage VGH is input. That is, the thin film transistor TFT corresponding to the i-th gate line GLi is turned on by the gate high voltage VGH.

On the other hand, the i-th buffer 133 is the i-th gate line GLi connected to the i-th buffer 133 by gate control signals GSC and GOE when the i-th gate line GLi is even. The modulated gate high voltage VGHM is input. That is, in the thin film transistor TFT corresponding to the i-th gate line GLi, the amount of charge charged in the corresponding even-numbered liquid crystal cells by the modulated gate high voltage VGHM is charged for a predetermined period less than the odd-numbered liquid crystal cells. do.

The gate low voltage VGL is input to the corresponding gate line GLi from the time point at which the i-th shift stage 131 ends. In addition, from the time point at which the i-th shift resist 131 is disabled, it can be seen that the i + 1 th shift stage is enabled so that the pixel data voltage is charged in the liquid crystal cells.

4 and 5, the gate high voltage VGH and the modulated gate high voltage VGHM are sampled for one horizontal period based on the source shift clock SSC and supplied to the gate lines, respectively. Can be.

Referring to FIG. 5, the pixel data voltage of the present invention is charged in the liquid crystal cells. In the vertical two-dot inversion liquid crystal display device in which polarities are inverted in every two liquid crystal cells in the vertical direction, The gate high voltage VGH is supplied, and the even-numbered gate lines are supplied with the modulated gate high voltage VGHM.

The modulated gate high voltage VGHM, which is input to the even-numbered gate lines, is a stepped pulse signal, which is charged in the corresponding liquid crystal cells to increase the charging time by the pixel data voltage charged in the preceding liquid crystal cell having the same polarity. The amount of charge of the pixel data voltage may be adjusted to equalize the charging time of the pixel data voltage charged before.

Although the present invention has been described as being limited to charging a small amount of charge of the pixel data voltage for a predetermined period using a modulated gate high voltage (VGHM) of stepped pulse type, the present invention is not limited thereto. The charging time of the pixel data voltage may be adjusted by delaying the turn-on time of the TFT by using the gate high voltage.

In the present invention, a liquid crystal display device having a vertical two-dot inversion method is limited and described. However, the present invention is not limited thereto, and an inversion liquid crystal in which positive and negative pixel data voltages are alternated for two or more liquid crystal cells in a vertical direction. Both display devices can be applied.

In the liquid crystal display according to the exemplary embodiment described above, the gate lines corresponding to the subsequent liquid crystal cells among the liquid crystal cells having the same polarity as well as adjacent to each other in the vertical direction with the modulated gate high voltage VGHM are vertically adjacent to each other. By supplying to the even-numbered gate lines in the exemplary embodiment of the present invention, the subsequent liquid crystal cells are controlled by controlling the turn-on time, that is, the time at which the thin film transistor TFT provided in the subsequent liquid crystal cells is turned on. The charging time of the pixel data voltage charged in the battery may be adjusted.

That is, in the vertical two-dot inversion type liquid crystal display device, the present invention is followed by the modulated gate high voltage VGHM even if the pixel data voltages of the same polarity are sequentially successively charged in the liquid crystal cells adjacent in the vertical direction. By controlling the turn-on time of the TFTs positioned in the liquid crystal cells of the LCD, the imbalance of the charged voltage of the preceding liquid crystal cells and the subsequent liquid crystal cells may be improved.

6 is a block diagram illustrating a liquid crystal display according to another exemplary embodiment of the present invention, and FIG. 7 is a waveform diagram illustrating a gate high voltage and a modulated gate high voltage of the liquid crystal display according to another exemplary embodiment of the present invention. to be.

6 and 7, a liquid crystal display according to another exemplary embodiment of the present invention includes a liquid crystal display panel 210 in which liquid crystal cells are arranged in a matrix, and gate lines of the liquid crystal display panel 210. A gate driver 230 for driving the GL1 to GLn and a data driver 220 for driving the data lines DL1 to DLm of the liquid crystal display panel 210.

Among the components of the liquid crystal display according to another exemplary embodiment of the present invention, other components except for the liquid crystal display panel 210, the data driver 220, and the gate driver 230 may be described with reference to FIGS. 1 to 3. The same elements as those of the liquid crystal display according to the exemplary embodiment will not be attached to the drawings, and detailed description thereof will be omitted.

The liquid crystal display panel 210 includes liquid crystal cells arranged in a matrix form. The liquid crystal cells control light transmittance by driving a liquid crystal positioned between the common electrode (not shown) and the pixel electrode 215 in response to the pixel data signal.

The liquid crystal display panel 210 includes a driving thin film transistor 211 connected to each of the liquid crystal cells and a precharge thin film transistor 213.

The driving thin film transistor 211 is connected to the second gate line GL2 to the nth gate line GLn and is supplied from the data lines DL1 to DLm in response to a gate signal from the gate driver 230. The signal is supplied to the corresponding liquid crystal cell.

The thin film transistor 213 for the precharge is connected to the first gate line GL1 to the n−1 th gate line GLn−1 and in response to a gate signal from the gate driver 230, the data lines DL1 to DLm. The pixel data signal supplied from the circuit is precharged to the corresponding liquid crystal cells. That is, the liquid crystal cells may be precharged by the pixel data signal supplied through the precharge thin film transistor 213 and then charge the pixel data signal supplied by the driving thin film transistor 211 in a short time.

The above-described liquid crystal display of the precharging driving method has not only the same polarity but also the subsequent liquid crystal cells among adjacent liquid crystal cells in the vertical two-dot inversion method, so that the charging time of the pixel data voltage is fast. On the other hand, since subsequent liquid crystal cells of different liquid crystal cells having different polarities are charged with pixel data voltages having different polarities, the charging time of the pixel data voltage supplied by the actual driving thin film transistor 211 is delayed.

According to the present invention, the charging time of the pixel data voltages of all liquid crystal cells can be made the same by supplying a gate high voltage VGHM having the same polarity and modulated by a gate line corresponding to subsequent liquid crystal cells among liquid crystal cells adjacent to each other. have.

Specifically, the gate high voltage VGH is supplied to the odd-numbered gate lines GL1, GL3, ... GLn-1, and the modulated gate high voltage (GLH) is supplied to the even-numbered gate lines GL2, GL4, ... GLn-1. VGHM) is supplied.

The modulated gate high voltage VGHM is a pulse shape which is delayed for a predetermined period so that the amount of charge can be controlled in the region in which the driving thin film transistor 211 is turned on, and the pixel data voltage charged by the precharging thin film transistor 213. The charging time is shortened by controlling the amount of charge of the pixel data voltage charged by the driving thin film transistor 211 to delay the charging time.

In the present invention, in the liquid crystal display of the precharging driving method, the vertical two-dot inversion method is limited and described. However, the present invention is not limited thereto and the positive and negative pixel data voltages of two or more liquid crystal cells in the vertical direction are not limited thereto. The alternating inversion type liquid crystal display device can be applied to all.

In the liquid crystal display according to another embodiment of the present invention described above, in the precharging driving method, the gate high voltage (VGH) having the same polarity in the vertical direction and modulating the gate lines of the adjacent liquid crystal cells (excellent). ) And the gate high voltage (VGHM) is supplied to the gate lines of the other liquid crystal cells (base number) to make the charging time of the pixel data voltage charged to all the liquid crystal cells as a whole, thereby reducing image quality such as streaks. Can be improved.

As described above, the present invention relates to a liquid crystal display device in which positive and negative pixel data voltages are alternated for at least two liquid crystal cells in a vertical direction, and thus, among the liquid crystal cells that are adjacent to each other and have the same polarity. By supplying a modulated gate high voltage to the liquid crystal cell of the control panel, the charge amount of the corresponding pixel data voltage is adjusted to equalize the charging time of all liquid crystal cells, thereby improving image quality degradation such as streaking.

The present invention relates to a liquid crystal display device in which positive and negative pixel data voltages are alternated for at least two liquid crystal cells in a vertical direction, wherein the liquid crystal cells not only are adjacent to each other but have the same polarity for a predetermined period of time. By supplying the delayed modulated gate high voltage to delay the turn-on time of the thin film transistors of the corresponding gate line to equalize the charging time of all liquid crystal cells, it is possible to improve image quality degradation such as streaks. have.

In addition, the present invention provides a precharging driving type liquid crystal display device, in which a modulated gate high voltage of a delayed form is supplied to a subsequent liquid crystal cell among liquid crystal cells having the same polarity in the vertical direction. By controlling the charging time of the pixel data voltage charged in the subsequent liquid crystal cells, the charging scheme of all liquid crystal cells is made the same, thereby reducing the image quality deterioration such as a streak phenomenon.

Those skilled in the art through the above description will be capable of various changes and modifications without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (10)

A liquid crystal display panel; A data driver configured to alternately supply positive and negative pixel data voltages to at least two liquid crystal cells in a vertical direction of the liquid crystal display panel; A gate voltage generator configured to generate a gate high voltage or a gate low voltage to turn on or off the thin film transistors of the liquid crystal cells in order to charge the pixel data voltage output from the data driver into liquid crystal cells for one line; A gate voltage modulator for modulating the gate high voltage generated from the gate voltage generator; And Among the liquid crystal cells that are adjacent to each other in the vertical direction and have the same polarity, the previous liquid crystal cells are driven using the gate high voltage, and the subsequent liquid crystal cells include a gate driver that drives the modulated gate high voltage. A liquid crystal display device. The method of claim 1, And wherein the modulated gate high voltage is a stepped pulse signal which reduces a charge amount of the pixel data voltage charged in liquid crystal cells of a corresponding gate line for a predetermined period of time. The method of claim 1, And the modulated gate high voltage delays the turn-on time of the thin film transistors of the corresponding gate line. The method of claim 2, The liquid crystal display device of claim 2, wherein the positive and negative pixel data voltages are alternated for each of the two liquid crystal cells in the vertical direction. The method of claim 1, And the liquid crystal display panel is driven by a precharging driving method. Supplying positive and negative pixel data voltages alternately in at least two liquid crystal cells in a vertical direction in a liquid crystal display panel; Generating a gate high voltage for turning on the thin film transistor of the liquid crystal display panel; Generating the gate high voltage using the gate high voltage; And And supplying the gate high voltage to the preceding liquid crystal cells among the liquid crystal cells adjacent to each other in the vertical direction and having the same polarity, and supplying the modulated gate high voltage to the subsequent liquid crystal cells. Method of driving the device. The method of claim 6, And wherein the modulated gate high voltage is a stepped pull signal. The method of claim 6, And wherein the modulated gate high voltage is a pulse signal that has been cut off for a predetermined period of time. The method of claim 6, The liquid crystal display panel of claim 2, wherein the positive and negative pixel data voltages are alternated for each of the two liquid crystal cells in the vertical direction. The method of claim 6, And the liquid crystal display panel is driven by a precharging driving method.
KR1020070044916A 2007-05-09 2007-05-09 Liquid crystal display device and driving method thereof KR20080099410A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112614470A (en) * 2020-12-31 2021-04-06 绵阳惠科光电科技有限公司 Display device and driving method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112614470A (en) * 2020-12-31 2021-04-06 绵阳惠科光电科技有限公司 Display device and driving method thereof

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