KR20130028596A - Method of controling dot inversion for lcd device - Google Patents

Abstract

PURPOSE: A method for controlling a dot inversion of a liquid crystal display device is provided to prevent a dim phenomenon and a smear phenomenon by controlling an inversion method. CONSTITUTION: An N-th horizontal line is enabled. A data voltage is supplied. Polarities between horizontally adjacent pixels are inverted in the N-th horizontal line. An M-th pixel and an (M+1)-th pixel have the same polarity. Polarities between vertically adjacent pixels are opposite. The polarity of the pixel is identically repeated in a twelfth pixel unit.

Description

Dot inversion control method of liquid crystal display device {METHOD OF CONTROLING DOT INVERSION FOR LCD DEVICE}

The present invention relates to a liquid crystal display device, and more particularly, to a dot inversion control method of a liquid crystal display device for solving a dim and color difference defect due to polarity bias when implementing a specific pattern in a dot inversion driving type liquid crystal display device. .

Various portable devices such as mobile phones and laptop computers, and information electronic devices that realize high resolution and high quality images such as HDTVs, have been applied to flat panel display devices. The demand for) is increasing. As such flat panel display devices, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and an organic light emitting diode (OLED) have been actively studied. However, And realization of a large area screen, a liquid crystal display (LCD) is in the spotlight at present.

The liquid crystal display device implements an image by adjusting the light transmittance of the liquid crystal cell on the liquid crystal panel according to the gray value of the data signal. However, when a direct current voltage is applied to the liquid crystal cells arranged in the liquid crystal panel for a long time, the light transmission characteristics of the liquid crystal cell are degraded. That is, a direct current fixation phenomenon occurs, which causes afterimages in the image displayed on the liquid crystal panel.

In order to prevent the above-mentioned DC fixation, an inversion type liquid crystal display device in which a data signal supplied to liquid crystal cells of a liquid crystal panel is inverted based on a common voltage Vcom has been proposed. The inversion method is classified into a frame inversion, a line inversion, a column inversion, and a dot inversion method.

Among these, the dot inversion method realizes an image having better image quality than the frame inversion method and the line inversion method.

However, when the liquid crystal display device is driven in a dot inversion method, the image quality of the liquid crystal display device may be degraded according to the correlation between the polarity of the data voltage charged in the liquid crystal cells and the image pattern displayed. According to the data voltage charged in the liquid crystal cell, the polarities of the data voltages charged in the liquid crystal cells do not balance the positive and negative polarities, and either polarity becomes the dominant polarity, and thus the common voltage (Vcom) applied to the common electrode. This is because ripple occurs at). This common voltage ripple causes the reference voltage of the liquid crystal cells to shake, shifting the common voltage to the dominant polarity. As a result, the observer may dim or smear the image displayed on the liquid crystal display. You can feel the phenomenon.

The problem pattern described above includes a shutdown pattern in which the pixel data of the white gray level and the pixel data of the black gray level are alternated by one pixel unit, and the pixel data of the white gray level and pixel data of the black gray level are alternated by 2 pixel units. There is a smear pattern.

Hereinafter, a problem pattern in which image quality deterioration occurs when the dot inversion type liquid crystal display is driven will be described with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating an example in which a vertical two-dot inversion LCD implements a shutdown pattern, and FIG. 2 is a diagram illustrating an example in which a smear pattern is implemented.

Referring first to FIG. 1, in the case of a 2-dot vertical inversion driving liquid crystal display in which RGB pixels are arranged in a stripe shape as shown in the drawing, pixels adjacent in the horizontal direction have polarities inverted from each other, and in the vertical direction. Adjacent pixels are driven to have polarities inverted by two pixels.

In the liquid crystal display of the above-described structure, when the shutdown pattern is displayed, in the case of the Nth horizontal line, the positive R pixels and the B pixels are superior to the negative G pixels, so that the common voltage Vcom is bipolar. By shifting, the data voltage data and the common voltage Vcom width of the G pixel become relatively larger. Accordingly, the upper part of the shutdown pattern is reddish, and the lower part is greenish, so that colors are different for each location.

Referring to FIG. 2, when a smear pattern is displayed on a two-dot vertical inversion driving liquid crystal display device arranged as shown in FIG. 2, one R pixel and two G pixels among pixels active in the Nth horizontal line are displayed. And one pixel is dominant to shift the common voltage Vcom to bipolarity, and on the N + 1th horizontal line, the common voltage Vcom is shifted to bipolar with its inversion. Therefore, only one B pixel and one R pixel are emphasized in each horizontal line, thereby generating a vertical Dim phenomenon.

The above phenomenon is a major cause of deterioration of the image quality.

In order to solve the above-mentioned problem of deterioration of image quality of the present invention, a liquid crystal display which improves a dim phenomenon and a smear phenomenon generated when a specific pattern is implemented by controlling an inversion method in a dot inversion liquid crystal display device. An object of the present invention is to provide a dot inversion control method of a display device.

In order to achieve the above object, a dot inversion control method of a liquid crystal display according to a first embodiment of the present invention, the step of enabling the N (N is a natural number) horizontal line; The polarities of the pixels adjacent in the horizontal direction are inverted with respect to each of the Nth horizontal lines, but the M (M is a multiple of 6) pixels and the M + 1 pixels have the same polarity, and the polarities between the pixels adjacent in the vertical direction are different from each other. Supplying a data voltage to be inverted with each other.

The polarity of the pixel may be equally repeated in the twelfth pixel unit.

The Nth horizontal line is characterized in that pixels of the odd and even horizontal lines have the same polarity, respectively.

In order to achieve the above object, a dot inversion control method of a liquid crystal display according to a second embodiment of the present invention, the step of enabling the N (N is a natural number) horizontal line; And polarities of pixels adjacent in the horizontal direction are inverted with respect to each of the Nth horizontal lines, but the M (M is a multiple of 6) pixels and the M + 1 pixels have the same polarity and are vertically adjacent two pixel units. Supplying a data voltage such that the polarities are inverted from each other.

The polarity of the pixel may be repeated equally in units of 12 pixels.

The Nth horizontal line is characterized in that the pixels of the Nth and N + 1th horizontal lines and the pixels of the N + 2th and N + 3th horizontal lines each have the same polarity.

According to a preferred embodiment of the present invention, in the driving method of the liquid crystal display device, a dot inversion driving method of improving image quality by changing polarities of adjacent pixels is applied, but each pixel is repeatedly driven with the same polarity every 12 dots. Even in a problem pattern, there is an effect that can realize a high quality image without deterioration of image quality.

FIG. 1 is a diagram illustrating an example in which a vertical two-dot inversion LCD implements a shutdown pattern, and FIG. 2 is a diagram illustrating an example in which a smear pattern is implemented.
3 is a block diagram illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.
4A to 4C are diagrams for describing a dot inversion control method of a liquid crystal display according to a first exemplary embodiment of the present invention.
5A to 5C are diagrams for describing a dot inversion control method of a liquid crystal display according to a second exemplary embodiment of the present invention.

Hereinafter, a dot inversion control method of a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a block diagram illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown, the liquid crystal display device to which the dot inversion control method of the present invention is applied includes a liquid crystal panel 100 for displaying an image and a driving circuit unit 120 for driving the liquid crystal panel 100.

The liquid crystal panel 100 crosses a plurality of data lines DL1 to DLm and a plurality of gate lines GL1 to GLn in a matrix form on a substrate using glass, and forms a plurality of pixel regions at intersections. In the pixel region, a thin film transistor TFT and a liquid crystal cell Clc are configured to display a screen.

The driving circuit unit 120 includes an interface unit 121, a timing controller 122, a gate driver 125, and a source driver 126.

The interface unit 121 outputs image related data, a clock signal CLK, a horizontal synchronous signal, a vertical synchronous signal, a data enable signal DE, and the like input to the driving circuit unit 120 from an external system such as a personal computer. The control signal including the input signal is supplied to the timing controller 122. As the interface 21, a low voltage differential signal (LVDS) interface and a TTL interface are used. In addition, the interface function may be collected and integrated into a single chip together with the timing controller 122.

The timing controller 122 performs timing of a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal Data Enable, DE, and a clock signal CLK, which are input from an external system through the interface 121. In response to the signal, the gate control signal for driving the gate driver 125, the source driver 126, and a data control signal for controlling the vertical polarity of the data voltage are generated.

In addition, the timing controller 122 arranges and converts image-related data input through the interface 121 into RGB DATA and supplies the same to the source driver 126.

The gate driver 125 controls turn-on / off of thin film transistors TFTs arranged on the liquid crystal panel 100 in response to gate control signals input from the timing controller 122. It plays a role.

The gate control signal described above includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal (Gate Output Enable, GOE), and the like. The gate start pulse GSP is a signal applied to the shift register generating the first gate pulse and controlling the shift register so that the first gate pulse is generated. The gate shift clock GSC is a clock signal input to all the shift registers in common, and is a clock signal for shifting the gate start pulse GSP. The gate output enable signal GOE serves to control the output of the shift registers.

Accordingly, the gate driver 125 generates gate driving signals in response to the above-described control signals and supplies the gate driving signals to the gate lines GL1 to GLn to enable each gate line, thereby turning on / off the thin film transistors. The image signal supplied from the source driver 126 is applied to the pixels connected to the TFTs by turning on / off.

The source driver 126 selects reference voltages of the input data in response to data control signals input from the timing controller 122, and controls the rotation angle of the liquid crystal molecules by supplying the selected reference voltages to the liquid crystal panel 100. .

The data control signal described above includes a source start pulse (SSP), a source sampling clock (SSC), a polarity control signal (Polarity, POL), and a source output enable signal (Source Output Enable, SOE). And the like. The source start pulse SSP is a signal for controlling the data sampling start timing of the source driver 126, and the source sampling clock SSC controls the sampling timing of data in each IC constituting the source driver corresponding to the rising or falling edge. Clock signal to control. In addition, the polarity control signal POL controls the horizontal polarity inversion timing of the data voltages simultaneously output from each of the source ICs. The source output enable signal SOE controls the output timing of the source driver 126.

The data driver 126 may include a shift register, a latch, a digital-to-analog converter, an output buffer, and the like, and the data driver 126 latches RGB data input under the control of the timing controller 122. Then, in response to the polarity control signal POL, RGB data is converted into an analog positive or negative gamma compensation voltage GAMMA to convert data polarities to data voltages having a repeating polar pattern of 12 dots inversion. Output to the liquid crystal panel 100 at the same time through (DL1 ~ DLm).

Here, in the 12-dot driving, the polarity change between the adjacent 12 pixels in the odd horizontal line is repeated in the same pattern. As shown in FIG. 4A, from the first pixel to the 12th pixel, "+,-, +,- , +,-,-, +,-, +,-, + "Is characterized in that it is repeated regularly. In addition, in the even-numbered horizontal line, "-, +,-, +,-, +, +,-, +,-, +,-", which is the inverse of the radix, is repeated.

This is to overcome the problem of deterioration in image quality caused by the implementation of the problem pattern in the conventional 1 dot and 2 dot inversion control method. The method is as follows.

4A to 4C are diagrams for describing a dot inversion control method of a liquid crystal display according to a first exemplary embodiment of the present invention, and FIG. 4A illustrates polarities of pixels for an arbitrary frame displaying an image. 4B and 4C illustrate the shape and polarity of the pixels in implementing the shutdown pattern and the smear pattern, respectively.

First, referring to FIG. 4A, the 12-dot inversion driving is applied to the liquid crystal display according to the first exemplary embodiment of the present invention, and in the 12-dot inversion driving, the polarity change between the adjacent 12 pixels in each horizontal line is the same pattern. Is repeated. In the following description, the first to twelfth pixels are described as unit 12 dots from the left to the right.

As shown in Fig. 4A, pixels adjacent to each other in the same vertical line are semielectroderous, and pixels adjacent to each other in the same horizontal line are repeated with the same polarity by 12 pixels.

That is, for each Nth horizontal line, polarities between pixels adjacent in the horizontal direction are reversed to each other, but M (M is a multiple of 6) pixels and M + 1 pixels have the same polarity, and polarities between pixels adjacent in the vertical direction are different from each other. Let it be reversed.

Specifically, the odd-numbered (N, N + 2) (N is a natural number) horizontal line has a polarity of "+,-, +,-, +,-,-, +,-," from the first pixel to the twelfth pixel. +,-, + "Is characterized in that the repeat (repeat) regularly. In addition, even-numbered (N + 1, N + 3) horizontal lines are semi-electrode "-, +,-, +,-, +, +,-, +, -, +,-"Is repeated.

In the case of implementing the shutdown pattern in the 12-dot inversion driving type liquid crystal display of this type, as shown in FIG. 4B, the black gray voltage and the white gray voltage are alternately applied, and 1 to 3 of the N-th horizontal line are alternately applied. The pixel has a large voltage difference from the common voltage Vcom as black gradation, and the 4 to 6 pixels have a level close to the common voltage Vcom as white gradation. Here, in the 1 to 3 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. The polarization order of the 7 to 12 pixels is the same as that of the 1 to 6 pixels described above, and the R and B pixels are the negative pixels, and the G pixels are the bipolar pixels.

1 to 3 pixels of the N + 1th horizontal line are white gradations and are close to the common voltage Vcom, and 4 to 6 pixels have white gradations and have a large voltage difference with the common voltage Vcom. Here, in the 4 to 6 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. The polarization order of the 7 to 12 pixels is the same as that of the 1 to 6 pixels described above, and the R and B pixels are negative pixels, and the G pixels are bipolar pixels.

The pixel voltages and polarities of the N + 2th and N + 3th horizontal lines are the same as the Nth and N + 1th horizontal lines, respectively.

That is, the odd-numbered horizontal lines and the even-numbered horizontal lines have the same pixel voltage and polarity, and the number of bipolar pixels and negative pixels having a large voltage difference with the common voltage Vcom is the same in each horizontal line. As a result, the common voltage Vcom is not shifted without shifting to one polarity so that color difference according to the position does not occur when the shutdown pattern is implemented.

Hereinafter, an example of implementing a smear pattern in a 12-dot inversion driving type liquid crystal display device according to a first embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the fourth to sixteenth pixels are described as unit 12 dots from the left to the right.

As shown in FIG. 4C, the black gray voltage and the white gray voltage are alternately applied to each of the two vertical lines, and the 4 to 9 pixels of the Nth horizontal line are the black gray to show a large voltage difference with the common voltage Vcom. 10 to 16 pixels have a white gradation and are close to the common voltage Vcom. Here, in the 4 to 9 pixels, R and B pixels are negative pixels, and G pixels are bipolar pixels. 10 to 16 pixels have the same polarity order as those of the above-mentioned 4 to 9 pixels, and R and B pixels are bipolar pixels, and G pixels are negative pixels.

4 to 9 pixels of the N + 1th horizontal line have a large voltage difference with the common voltage Vcom as white gradation, and 10 to 16 pixels have a level close to the common voltage Vcom as black gradation. Here, in the 4 to 9 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. 10 to 16 pixels have the same polarity order as those of the above 4 to 9 pixels, and R and B pixels are negative pixels, and G pixels are bipolar pixels.

The pixel voltages and polarities of the N + 2th and N + 3th horizontal lines are the same as the Nth and N + 1th horizontal lines, respectively.

That is, in the horizontal line, the polarity of the R pixel and the B pixel is superior to the G pixel, and the polarity thereof is negative, and the number of negative pixels having a large voltage difference with the common voltage Vcom is large in the horizontal line. Therefore, the common voltage is biased and the voltage is lowered by the common voltage shift (Vcom shift).

In addition, since the polarity of the R pixel and the B pixel is superior to the G pixel, and the polarity thereof is bipolar, the number of bipolar pixels having a large voltage difference with the common voltage Vcom is large in the horizontal line. The common voltage is biased to increase the voltage due to the common voltage shift (Vcom shift).

Therefore, when the vertical line is compensated for the increased difference between polarities for each adjacent pixel, the vertical dim phenomenon does not occur when the smear is implemented.

Hereinafter, a 12-dot inversion driving type liquid crystal display device according to a second embodiment of the present invention will be described with reference to the drawings.

5A to 5C are diagrams for describing a dot inversion control method of a liquid crystal display according to a second exemplary embodiment of the present invention, and FIG. 5A illustrates polarities of pixels for an arbitrary frame displaying an image. 5B and 5C are diagrams illustrating shapes and polarities of pixels in implementing a shutdown pattern and a smear pattern, respectively.

First, referring to FIG. 5A, in a liquid crystal display according to a second exemplary embodiment of the present invention, 12 dot inversion driving is applied, and in the 12 dot inversion driving, polarity change between adjacent 12 pixels in each horizontal line is the same pattern. Is repeated. In the following description, the first to twelfth pixels are described as unit 12 dots from the left to the right.

As shown in Fig. 5A, each pixel is semielectrodeposited by two pixels adjacent to each other on the same vertical line, and 12 pixels adjacent to each other on the same horizontal line are repeated with the same polarity.

That is, for each Nth horizontal line, the polarities of pixels adjacent in the horizontal direction are reversed to each other, but the M (M is a multiple of 6) pixels and the M + 1 pixels have the same polarity, and are arranged in two pixel units adjacent in the vertical direction. Make sure the polarities are reversed.

Specifically, the N, N + 1th horizontal line has a regular polarity of "+,-, +,-, +,-,-, +,-, +,-, +" from the first pixel to the twelfth pixel. It is characterized in that it is repeated (repeat). In addition, the N + 2, N + 3rd horizontal line is the semi-electrode "-, +,-, +,-, +, +,-, +" of the N, N + 1th (N, N + 1) horizontal line. ,-, +,-"Is repeated.

When the shutdown pattern is implemented in the 12-dot inversion driving type liquid crystal display of this type, as shown in FIG. 5B, the black gray voltage and the white gray voltage are alternately applied, and 1 to 3 of the Nth horizontal line are alternately applied. The pixel has a large voltage difference from the common voltage Vcom as black gradation, and the 4 to 6 pixels have a level close to the common voltage Vcom as white gradation. Here, in the 1 to 3 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. The polarization order of the 7 to 12 pixels is the same as that of the 1 to 6 pixels described above, and the R and B pixels are the negative pixels, and the G pixels are the bipolar pixels.

The pixels 1 to 3 of the N + 1th horizontal line are white gradations and are close to the common voltage Vcom, and the pixels 4 to 6 have a large voltage difference from the common voltage Vcom as white gradations. Here, in the 4 to 6 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. The polarization order of 7 to 12 pixels is opposite to that of the aforementioned 1 to 6 pixels, and R and B pixels are cathode pixels, and G pixels are bipolar pixels.

1 to 3 pixels of the N + 2th horizontal line have a large voltage difference from the common voltage Vcom as black gradation, and 4 to 6 pixels are close to the common voltage Vcom as white gradation. Here, in the 1 to 3 pixels, the R and B pixels are negative pixels, and the G pixels are bipolar pixels.

In addition, 7 to 12 pixels have the opposite polarity order to 1 to 6 pixels described above, and R and B pixels are bipolar pixels, and G pixels are negative pixels.

Lastly, 1 to 3 pixels of the N + 3 horizontal line are white gradations, which are close to the common voltage Vcom, and 4 to 6 pixels have white gradations, which have a large voltage difference from the common voltage Vcom. . Here, in the 4 to 6 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. The polarization order of 7 to 12 pixels is opposite to that of the aforementioned 1 to 6 pixels, and R and B pixels are cathode pixels, and G pixels are bipolar pixels.

That is, although the pixel voltage and polarity of each horizontal line are different from each other, since the number of bipolar pixels and negative pixels having a large voltage difference with the common voltage Vcom in each horizontal line is the same, the common voltage is balanced. Since (Vcom) does not shift without shifting to one polarity, color difference according to the position does not occur when implementing the shutdown pattern.

Hereinafter, an example of implementing a smear pattern in a 12-dot inversion driving type liquid crystal display device according to a second embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the fourth to sixteenth pixels are described as unit 12 dots from the left to the right.

As shown in FIG. 5C, the black gray voltage and the white gray voltage are alternately applied to each of the two vertical lines, and the 4 to 9 pixels of the Nth horizontal line are the black gray and show a large voltage difference with the common voltage Vcom. 10 to 16 pixels have a white gradation and are close to the common voltage Vcom. Here, in the 4 to 9 pixels, R and B pixels are cathode pixels, and G pixels are bipolar pixels. 10 to 16 pixels have the opposite polarity order to 4 to 9 pixels described above, and R and B pixels are bipolar pixels, and G pixels are negative pixels.

The pixel voltage and polarity of the N + 1th horizontal line are the same as the Nth horizontal line.

Further, 4 to 9 pixels of the N + 2th horizontal line have a large voltage difference with the common voltage Vcom as white gradation, and 10 to 16 pixels have a level close to the common voltage Vcom as black gradation. Here, in the 4 to 9 pixels, R and B pixels are bipolar pixels, and G pixels are negative pixels. 10 to 16 pixels have the opposite polarity order to 4 to 9 pixels described above, and R and B pixels are negative pixels, and G pixels are bipolar pixels.

In addition, the pixel voltage and polarity of the N + 3th horizontal line are the same as the N + 2th horizontal line.

That is, the N, N + 1th horizontal line has a negative polarity of the R pixel and the B pixel than the G pixel and its polarity is negative, and has a large voltage difference with the common voltage Vcom in the horizontal line. Since the number of is large, the common voltage is negatively biased and the voltage is lowered by the common voltage shift (Vcom shift).

In addition, in the N + 2, N + 3th horizontal lines, the polarity of the R pixel and the B pixel is superior to the G pixel, and the polarity thereof is bipolar, and the bipolar pixel has a large voltage difference with the common voltage Vcom in the horizontal line. Since the number of is large, the common voltage is biased to be bipolar and the voltage is increased due to the common voltage shift (Vcom shift).

However, when the vertical line is compensated for the increased difference between the polarities of two adjacent pixels, the vertical dim phenomenon does not occur when the smear is implemented.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

100: liquid crystal panel 120: drive circuit
121: interface unit 122: timing controller
125: gate driver 126: source driver

Claims (6)

As a dot inversion control method of a liquid crystal display device,
Enabling the N (N is a natural number) horizontal line; And
In each of the Nth horizontal lines, polarities between pixels adjacent in the horizontal direction are reversed to each other, but M (M is a multiple of 6) pixels and M + 1 pixels have the same polarity, and polarities between pixels adjacent in the vertical direction are reversed from each other. Supplying the data voltage as much as possible
Dot inversion control method of the liquid crystal display comprising a. The method of claim 1,
The polarity of the pixel is the same in every 12th pixel unit dot inversion control method of the liquid crystal display, characterized in that repeated. The method of claim 1,
The Nth horizontal line is,
A dot inversion control method for a liquid crystal display device, characterized in that pixels of the odd and even horizontal lines each have the same polarity. As a dot inversion control method of a liquid crystal display device,
Enabling the N (N is a natural number) horizontal line; And
For each of the Nth horizontal lines, polarities between pixels adjacent in the horizontal direction are reversed to each other, but the M (M is a multiple of 6) pixels and the M + 1 pixels have the same polarity, and are polarized in two adjacent pixel units in the vertical direction. Supplying the data voltages such that they are inverted from each other
Dot inversion control method of the liquid crystal display comprising a. The method of claim 4, wherein
The polarity of the pixel is repeated in the same unit of 12 pixels dot inversion control method of a liquid crystal display device. The method of claim 4, wherein
The Nth horizontal line is,
The pixel of the Nth and N + 1th horizontal lines and the pixels of the N + 2th and N + 3th horizontal lines have the same polarity, respectively.

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