KR20090065110A

KR20090065110A - Liquid crystal display device

Info

Publication number: KR20090065110A
Application number: KR1020070132554A
Authority: KR
Inventors: 정용채
Original assignee: 엘지디스플레이 주식회사
Priority date: 2007-12-17
Filing date: 2007-12-17
Publication date: 2009-06-22

Abstract

An LCD(Liquid Crystal Display) device is provided to stably supply common voltage to each sub pixel by preventing the common voltage from shift to a positive or negative direction with balancing charging voltage of the positive and negative sub pixels. Sub pixel RGBW(Red, Green, Black, and White) between two pixels, which are neighboring in a horizontal direction, is symmetrically arranged based on a boundary when a quad type pixel is arranged on an LCD panel driven in a dot inversion mode. Two neighboring pixels are an odd and even pixel. The sub pixel RGBW is clockwise arranged in RGBW order at the odd pixel based on second quadrant. The sub pixel RGBW is arranged in GRWB order at the even pixel.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel array technology of a liquid crystal panel in a liquid crystal display device. In particular, when a quad type pixel is arranged on a liquid crystal panel, crosstalk, greenish, or vertical dim can be prevented from occurring. The present invention relates to a liquid crystal display device adapted to be arranged.

Recently, with the development of information technology (IT), the importance of the flat panel display device as a visual information transmission medium has been further emphasized, and low power consumption, thinning, light weight, and high quality are required to secure improved competitiveness in the future.

A liquid crystal display (LCD), which is a typical display device of a flat panel display device, is an apparatus for displaying an image using optical anisotropy of liquid crystal, and has advantages such as thin, small size, low power consumption, and high quality.

Such a liquid crystal display device is a display device in which image information is individually supplied to pixels arranged in a matrix, and a desired image is displayed by adjusting light transmittance of the pixels. Accordingly, the liquid crystal display includes a liquid crystal panel in which pixels, which are the smallest unit for implementing an image, are arranged in an active matrix form, and a driving unit for driving the liquid crystal panel. Since the LCD does not emit light by itself, a backlight unit is provided to supply light to the LCD. The driver includes a timing controller and a data driver and a gate driver.

The driving method of the liquid crystal panel includes a line inversion, column inversion, and dot inversion depending on the phase of the pixel (or data) signal applied to the data line. have. The line inversion method is a method of inverting and applying a phase of a pixel signal applied to a data line for each line, and the column inversion method is a method of inverting and applying a phase of a pixel signal applied to a data line for each column. The dot inversion method is a method of inverting and applying a phase of a pixel signal applied to a data line for each column and line.

As described above, the reason for driving the liquid crystal in the inversion method is to prevent the deterioration phenomenon by the liquid crystal is continuously arranged in only one direction. In other words, the inversion method is to alternately supply a positive image signal and a negative image signal so that the liquid crystals are arranged in the right direction and then in the opposite direction.

Recently, in addition to the red, green and blue (RGB) subpixels that are basically used in the liquid crystal panel to express images of various colors, a white subpixel (W) that can only adjust the amount of light without any color component is added. In order to improve the pixel structure and to improve the luminance through the introduction of quad-type pixels forming one pixel with four subpixels of green, blue, and white (RGBW), research is being actively conducted.

FIG. 1 is a layout view of the quad type pixels, and it can be seen that RGBW subpixels are arranged in a quad type forming one pixel.

FIG. 2 (a) shows a 1 × N (horizontal × vertical) inversion structure of a conventional pixel structure for the RGBW pixel. In such a structure, subpixels between adjacent pixels are not arranged with corresponding polarities. As a result, a phenomenon in which the common voltage Vcom is shifted in the positive or negative polarity direction occurs, thereby causing the common voltage Vcom to become unstable, thereby causing crosstalk and greenish phenomenon. The image quality is reduced.

FIG. 2 (b) shows a 2N × M (horizontal × vertical) inversion structure of the conventional pixel structure for the RGBW pixel. In such a structure, the unstable state of the common voltage does not occur. As a reference, due to the difference between the left and right parasitic capacitances (Cdp), the pixels were bright at a certain interval, and a dark vertical dim problem occurred, especially in the TN mode model.

The conventional pixel structure proposed to solve such a problem is shown in FIG. 3. Referring to the pixel structure of FIG. 3, two subpixels having the same polarity are arranged in a diagonal direction, and the remaining two subpixels are arranged in a reverse diagonal direction, respectively, and the next pixel is arranged in such a manner that their polarities are interchanged with each other. Able to know. However, the pixel structure shown in FIG. 3 has a defect in that circuit components such as a data driving integrated device and a gate driving integrated device employing the RGB pixel structure, which are conventionally used, cannot be shared.

As described above, in the liquid crystal panel of the liquid crystal display device according to the prior art, the common voltage becomes unstable in the liquid crystal panel having a 1 × N inversion structure, resulting in crosstalk, greenish phenomenon, and the like, resulting in deterioration in image quality.

In the liquid crystal panel of 2N × M inversion structure, the pixels are bright at regular intervals due to the difference of left and right parasitic capacitance with respect to the pixels, and a dark vertical dim problem occurs in the TN mode model. There was a problem that the symptoms appeared more seriously.

In addition, in a liquid crystal panel having a structure in which subpixels having the same polarity are arranged diagonally in diagonal directions, circuit components such as data driving integrated devices and gate driving integrated devices employing the RGB pixel structure, which are conventionally used in general, may be shared. There was a problem that could not be.

Accordingly, an object of the present invention is to arrange such that their charging voltages are balanced with each other when arranging quad type pixels on a liquid crystal panel driven by a dot inversion method.

In order to achieve the above object, the present invention provides a symmetrical structure of subpixel RGBW between two adjacent pixels in a horizontal direction when a quad type pixel is arranged in a liquid crystal panel driven by a dot inversion method. It is characterized by arrangement.

The driving method of the liquid crystal panel is a horizontal 1 dot vertical 2 dot inversion method or a vertical 1 dot vertical 1 dot inversion driving method.

According to the present invention, when a pixel of a quad type is arranged in a liquid crystal panel, subpixel RGBWs of two pixels adjacent in a horizontal direction are arranged to form a symmetrical structure with respect to a boundary surface, thereby applying positive and negative polarities when applying the dot inversion method. Since the charging voltages of the corresponding subpixels are balanced with each other, the common voltage does not shift in the positive or negative direction, thereby stably supplying the common voltage to each subpixel on the liquid crystal panel.

In addition, since the common voltage is stably supplied, there is an effect of fundamentally preventing crosstalk, greenish, and vertical dim from occurring.

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

4 is a block diagram of a liquid crystal display device to which the present invention is applied. As shown in FIG. 4, the gate control signal GDC and the data control signal DDC for controlling the driving of the gate driver 2 and the data driver 3 are shown. A timing controller 1 for outputting the digital pixel data RGB and rearranging the digital pixel data RGB; A gate driver 2 outputting a gate signal to each gate line GL1 to GLn of the liquid crystal panel 4 in response to a gate signal control signal supplied from the timing controller 1; A data driver (3) for supplying a pixel signal to each of the data lines (DL1 to DLm) of the liquid crystal panel (4) in response to a data signal control signal supplied from the timing controller (1); In the display of an image having the pixels driven by the gate signal and the pixel signal in a matrix form, a liquid crystal panel arranged such that quad-type subpixel RGBWs of two pixels adjacent in a horizontal direction have a symmetrical structure with respect to a boundary surface. It comprises (4).

5 illustrates a structure of a quad type subpixel on the liquid crystal panel 4 according to the present invention. As shown in FIG. 5, the subpixel RGBW of the odd pixels and the even pixel adjacent in the horizontal direction are symmetrical with respect to the boundary surface. Arranged to be a structural structure.

Referring to Figure 6 attached to the operation of the present invention configured as described above in detail as follows.

The timing controller 1 includes a gate control signal GDC and a data driver 3 for controlling the gate driver 2 using the vertical / horizontal synchronization signals Hsync / Vsync and the clock signal CLK supplied from the system. Outputs a data control signal (DDC) for controlling. In addition, the timing controller 1 samples the digital pixel data RGB input from the system, rearranges the digital pixel data RGB, and supplies the same to the data driver 3.

As the gate control signal GDC, there are a gate start pulse GSP, a gate shift clock GSC, a gate out enable GOE, and the like, and as a data control signal DDC, a source start pulse SSP and a source shift clock. (SSC), source out enable (SOE), polarity signal (POL), and the like.

The gate driver 2 sequentially supplies the gate signals to the gate lines GL1 to GLn in response to the gate control signal GDC input from the timing controller 1, thereby corresponding thin film transistor TFT on the horizontal line. ) Are turned on. Accordingly, pixel signals supplied through the data lines DL1 to DLm are stored in the respective storage capacitors C _ST through the thin film transistors TFT.

In more detail, the gate driver 2 shifts the gate start pulse GSP according to the gate shift clock GSC to generate a shift pulse. The gate driver 2 supplies a gate signal consisting of gate on / off sections (signals) to the corresponding gate line GL in a horizontal period in response to the shift clock. In this case, the gate driver 2 supplies a gate-on signal only in an enable period in response to the gate-out enable signal GOE, and supplies a gate-off signal (gate low signal) in other periods.

The data driver 3 converts the pixel data RGB into an analog pixel signal (data signal or data voltage) corresponding to the gray scale value in response to the data control signal DDC input from the timing controller 1. The pixel signal thus converted is supplied to the data lines DL1 to DLm on the liquid crystal panel 4.

In more detail, the data driver 3 generates the sampling signal by shifting the source start pulse SSP according to a source shift clock. Subsequently, the data driver 3 sequentially inputs and latches the pixel data RGB by a predetermined unit in response to the sampling signal. The data driver 3 converts the latched pixel data RGB for one line into an analog pixel signal and supplies the same to the data lines DL1 to DLm.

The liquid crystal panel 4 is formed in each crossing portion of the plurality of liquid crystal cells (C _LC) arranged in a matrix, a data line (DL1~DLm) and gate line (GL1~GLn) each of the liquid crystal cell (C _LC And a thin film transistor (TFT) connected to each of them.

The thin film transistor TFT is turned on when the gate signal is supplied from the gate line GL, and supplies the pixel signal supplied through the data line DL to the liquid crystal cell C _LC . The thin film transistor TFT is turned off when the gate off signal is supplied through the gate line GL to maintain the pixel signal charged in the liquid crystal cell C _LC .

The liquid crystal cell C _LC includes a pixel electrode connected to a common electrode and a thin film transistor TFT with a liquid crystal interposed therebetween. The liquid crystal cell C _LC further includes a storage capacitor C _ST so that the charged pixel signal is stably maintained until the next pixel signal is charged. The storage capacitor C _ST is formed between the pixel electrode and the previous gate line. In the liquid crystal cell C _LC , an arrangement state of liquid crystals having dielectric anisotropy varies according to pixel signals charged through the thin film transistor TFT, and light transmittance is adjusted accordingly to implement gradation.

Meanwhile, in the present invention, in arranging the quad type pixels on the liquid crystal panel 4, the subpixel RGBW of any one pixel is symmetrical with the subpixel RGBW of the adjacent pixels in the horizontal direction so that the common voltage is stabilized. It was possible to maintain the state, which will be described in more detail as follows.

FIG. 5 illustrates a pixel structure according to the present invention on the liquid crystal panel 4. In the quad type pixel structure in which four subpixels of red, green, blue, and white (RGBW) form one pixel, FIG. It can be seen that the subpixel RGBW of one pixel is symmetrical with the subpixel RGBW of the adjacent pixels in the horizontal direction.

In other words, when the horizontal and the adjacent boundary of the odd and excellent pixels are referred to, the odd pixels sequentially arrange the RGBW subpixels in the clockwise direction with respect to the two quadrants, and in the even pixel, in the clockwise direction with respect to the two quadrants. GRWB subpixels were arranged sequentially.

FIG. 6 illustrates an example in which the pixel structure as shown in FIG. 5 is applied to a horizontal 1-dot vertical 2-dot inversion. In such a case, subpixels having the same polarity having different polarities are adjacent to adjacent pixels in the horizontal direction. You can see that it is arranged.

That is, when the pixels of the first horizontal line are taken as an example, as shown in FIG. 6A, the negative R subpixels of the second pixel and the positive R subpixels of the third pixel are arranged adjacent to each other.

As shown in FIG. 6B, the negative G subpixel of the first pixel and the positive G subpixel of the second pixel are arranged adjacent to each other. Similarly, the negative G subpixel of the third pixel and the positive G subpixel of the fourth pixel are arranged adjacently.

As shown in FIG. 6C, the negative B subpixel of the first pixel and the positive B subpixel of the second pixel are arranged adjacent to each other. Similarly, the negative B subpixel of the third pixel and the positive B subpixel of the fourth pixel are arranged adjacently.

In this way, the charging voltages of the corresponding subpixels of the positive and negative polarities are balanced with each other so that the common voltage is not shifted in the positive or negative direction. Accordingly, the common voltage can be stably supplied to each subpixel on the liquid crystal panel 4.

FIG. 7 illustrates an example in which the pixel structure of the present invention as shown in FIG. 5 is applied to a horizontal 1 dot vertical 1 dot inversion, and B subpixel is exemplarily shown. Even in such a case, it can be seen that B subpixels having different polarities are arranged adjacent to each other in the horizontal direction as in the above description.

Therefore, the charging voltages of the corresponding subpixels of the positive and negative polarities are balanced with each other so that the common voltage is not shifted in the positive or negative direction. Accordingly, the common voltage can be stably supplied to each subpixel on the liquid crystal panel 4.

1 is a layout view of quad type pixels.

2 (a) is a pixel arrangement diagram of a horizontal 1 dot vertical 2 dot inversion method,

Figure 2 (b) is a pixel arrangement diagram of a horizontal 2-dot vertical 2-dot inversion method.

3 is a pixel arrangement diagram of a horizontal 2-dot vertical 1-dot inversion scheme according to the prior art;

4 is a driving block diagram of a liquid crystal display device to which the present invention is applied.

5 is a pixel layout view of a liquid crystal panel according to the present invention;

6 (a) to 6 (c) are explanatory diagrams showing a symmetrical structure for each RGB subpixel.

FIG. 7 is a pixel layout view of a horizontal 1 dot vertical 1 dot inversion scheme according to another embodiment of the present invention. FIG.

*** Description of the symbols for the main parts of the drawings ***

1: Timing Controller 2: Gate Driver

3: data driver 4: liquid crystal panel

Claims

When a quad type pixel is arranged on a liquid crystal panel driven by a dot inversion method, a subpixel RGBW between two adjacent pixels in a horizontal direction is arranged to form a symmetrical structure with respect to a boundary surface.

The liquid crystal display device according to claim 1, wherein two pixels adjacent in the horizontal direction are odd pixels and even pixels.

The RGB pixel of claim 1, wherein the subpixel RGBW is arranged in the RGBW order in the clockwise direction with respect to the quadrants in the odd pixels, and in the GRWB order in the even pixels, based on the boundary of the odd and excellent pixels adjacent to each other in the horizontal direction. A liquid crystal display device, characterized in that arranged.

The liquid crystal display of claim 1, wherein the dot inversion method is a horizontal 1 dot vertical 2 dot inversion method.

The liquid crystal display of claim 1, wherein the dot inversion method is a horizontal 1 dot vertical 1 dot inversion method.