KR20070071229A - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is provided to prevent a specific polarity from being superior at a liquid crystal panel by alternately applying a vertical 2-dot inversion method and a horizontal 2-dot inversion method according to liquid crystal panel areas and times, thereby preventing lowering of the quality of pictures. A liquid crystal panel(100) is divided into a first area and a second area. A plurality of pixels are arranged on the liquid crystal panel. A timing control unit(142) receives a vertical synchronous signal and an image voltage from the outside, and outputs first and second driving selection signals(SEL1,SEL2) deciding the image voltage and an image voltage applying method. A polarity control unit(143) outputs a first polarity signal(POL1) and a second polarity signal(POL2) having different pulse widths according to the first and second driving selection signals.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a view showing a general liquid crystal display device.

FIG. 2A illustrates polarities of pixels implemented in a 2-dot inversion scheme. FIG.

FIG. 2B is a diagram showing polarities of pixels changed in a frame consecutive to FIG. 2A; FIG.

Figure 3 is an exemplary view showing a waveform change of the scan signal according to the dominant polarity.

4 is a view showing a liquid crystal display device according to the present invention;

FIG. 5A illustrates a change in polarity of pixels arranged in a first region of the liquid crystal panel of FIG. 4 in units of frames; FIG.

FIG. 5B is a diagram illustrating a polarity change of pixels arranged in a second region of the liquid crystal panel of FIG. 4 in units of frames; FIG.

6 is an exemplary view showing waveforms of control signals for driving the liquid crystal display of FIG. 4 as shown in FIG.

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

100a: first substrate 100b: second substrate

100: liquid crystal panel 140: data printed circuit board

142: timing controller 143: polarity controller

145: data driving circuit 148: TCP

150: gate printed circuit board 155: gate driving circuit

POL1: first polarity signal POL2: second polarity signal

SEL1: first drive selection signal SEL2: second drive selection signal

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which the vertical two-dot inversion method and the horizontal two-dot inversion method are alternately applied for each region of the liquid crystal panel.

Recently, various display devices for visually implementing information have been developed to replace the cathode ray tube, which has been frequently used. Among them, liquid crystal display devices are thin and light, and their demand is increasing due to low power consumption and vivid image quality.

A liquid crystal display device is an apparatus which displays the image of various colors by changing the light transmittance of a liquid crystal by an electric field using the optical anisotropy and the electric field anisotropy of a liquid crystal.

1 is a view showing a general liquid crystal display device.

Referring to FIG. 1, a liquid crystal display device includes a liquid crystal panel 10 for displaying an image, a data driver 20 for supplying an image voltage to the liquid crystal panel 10, and a scan signal for the liquid crystal panel 10. It is configured to include a gate driver 30 to be.

In the liquid crystal panel 10, a thin film transistor array substrate and a color filter substrate are bonded to each other, and liquid crystal is injected between the thin film transistor array substrate and the color filter substrate.

The plurality of data lines 22 and the gate lines 32 are vertically intersected in the liquid crystal panel 10, and the plurality of pixels P is formed by the intersection of the data lines 22 and the gate lines 32. Is partitioned.

Each pixel P includes a thin film transistor, which is electrically connected to the gate line 32 and the data line 22.

The gate line 32 extends to the edge region of the liquid crystal panel 10 and is electrically connected to the gate driver 30. The data line 22 also extends to the edge region of the liquid crystal panel 10 and thus the data driver. Electrically connected with 20.

The gate driver 30 sequentially outputs a scan signal to the gate line 32. At this time, all of the thin film transistors electrically connected to the gate line 32 are turned on. The data driver 20 applies an image voltage to the pixels P while the thin film transistors are turned on.

The image voltage is applied to a pixel electrode provided for each pixel P, and the pixel electrode together with a common electrode provided on the color filter substrate applies an electric field to a liquid crystal corresponding to each pixel P to form an array of liquid crystal molecules. Change. As the arrangement of the liquid crystal molecules changes, the light transmittance also changes, so that each pixel P is controlled by the pixel electrode and the common electrode, thereby realizing images of various colors.

There are various methods of applying the image voltage applied to the pixel electrode and the common voltage applied to the common electrode. Recently, the most commonly used methods are the 1-dot inversion method and the 2-dot inversion method.

The dot inversion method changes the polarity of the voltage difference due to the common voltage and the image voltage for each adjacent pixel, thereby preventing deterioration of the liquid crystal that may occur as the voltage of the same polarity is continuously maintained.

However, the dot inversion method also displays a picture of a specific pattern such as a checkered pattern. As a result of deterioration in image quality, recently, a two-dot inversion method that compensates for the disadvantages of the dot inversion method has been widely used.

FIG. 2A is a diagram illustrating polarities of pixels implemented in a 2-dot inversion scheme, and FIG. 2B is a diagram illustrating polarities of pixels changed in a continuous frame of FIG. 2A.

Although not shown in the drawing, the pixels R, G, and B are arranged in a plurality of rows N-1 to N + 6 in the liquid crystal panel.

An image voltage and a common voltage are applied to the pixels R, G, and B in a vertical two-dot inversion scheme in which polarities change by two pixels R, G, and B in the vertical direction. Polarity markings (+ or-) on the pixels R, G, and B indicate voltage polarities of image voltages based on a common voltage.

The polarities of the image voltages implemented in the pixels P pass from the first frame to the second frame, and the polarities of the image voltages are changed by two pixels in the vertical direction. In particular, in the case where a specific pattern is displayed on the liquid crystal panel (here, the hatched portion is the portion where the image is implemented), since the dominant polarity is different for each pixel row N-1 to N + 6, the corresponding pixel row ( The pixels R, G, and B of N-1 to N + 6 may be affected by voltages of a specific polarity.

3 is an exemplary view showing a waveform change of a scan signal according to a dominant polarity.

Referring to FIG. 3, a scan signal sequentially output to a plurality of gate lines maintains a high potential state by one horizontal period, and maintains a low potential state during the remaining periods of one frame period. If the characteristic polarity prevails in the rows N-1 to N + 6, it also affects the waveform of the scan signal.

The gate line to which the scan signal is applied is electrically connected to the gate electrode of the thin film transistor of each pixel (R, G, B), the drain electrode of the thin film transistor is connected to the pixel electrode, and the source electrode is connected to the data line. . In this case, since the coupling capacitance between the source electrode and the gate electrode and the coupling capacitance between the drain electrode and the gate electrode exist in the thin film transistor, the voltage of the scan signal applied to the gate line according to the voltage of the image voltage applied to the thin film transistor. Levels can also vary.

As described above, in the vertical two-dot inversion driving, since the two consecutive pixels R, G, and B have the same dominant polarity, the voltage ripples in the same direction to the scan signal applied to the two consecutive gate lines. (ripple) occurs instantaneously. As such, the predominant polarity in the pixel rows N-1 to N + 3 causes temporary waveform distortion in the scan signal applied to the liquid crystal display device, resulting in deterioration of image quality such as greenish and horizontal lines. .

The present invention was devised to solve the conventional problems as described above, and an object of the present invention is to divide the liquid crystal panel and drive the vertical two-dot inversion and the horizontal two-dot inversion, respectively, and further, every frame The present invention provides a liquid crystal display device which converts a vertical two-dot inversion and a horizontal two-dot inversion for each driving.

According to an aspect of the present invention, a liquid crystal display device includes: a liquid crystal panel divided into a first region and a second region; A plurality of pixels arranged in the liquid crystal panel; A timing controller which receives a vertical synchronization signal and an image voltage from the outside and outputs first and second drive selection signals for determining the image voltage application method together with the image voltage; A polarity controller for outputting a first polarity signal and a second polarity signal having different pulse widths according to the first and second drive selection signals; A first group of data driving circuits for applying an image voltage to the pixels corresponding to the first region and the pixels corresponding to the second region by different image voltage application methods according to the first and second polar signals; It consists of two groups of data driving circuits.

4 is a view showing a liquid crystal display according to the present invention.

Referring to FIG. 4, the liquid crystal display device receives and outputs a liquid crystal panel 100 in which the first substrate 100a and the second substrate 100b are joined together with an external image voltage DATA, and outputs vertical two-dots. A timing controller 142 for outputting first and second drive selection signals SEL1 and SEL2 for selecting inversion and horizontal two-dot inversion driving; and first and second drive selection signals of the timing controller 142. The image voltage DATA is commonly applied from the polarity control unit 143 and the timing controller 142 to output the first and second polarity signals POL1 and POL2 having different voltages according to SEL1 and SEL2. Outputting the image voltage DATA of horizontal 2-dot or vertical 2-dot to the liquid crystal panel 100 according to the first polarity signal POL1 and the second polarity signal POL2 of the polarity control unit 143, respectively. And a data driver circuit 145a of the first group and a data driver circuit 145b of the second group.

The timing controller 142 and the polarity controller 143 are formed on the printed circuit board 140, and the first and second groups of data driver circuits 145 are formed of the liquid crystal panel 100 and the data printed circuit board ( 140 is mounted on a TCP (tape carrier package, 148) that electrically connects each other.

The gate printed circuit board 140 is connected to the other side of the liquid crystal panel 100 by the TCP 148. Gate driving circuits 155 are mounted on the TCP 148 connected to the gate printed circuit board 140, respectively.

The timing controller 142 receives an image voltage DATA from the outside, and transfers the image voltage DATA to the first and second groups of data driving circuits 145. In addition, the timing controller 142 has a different voltage, and outputs a first drive select signal SEL1 and a second drive select signal SEL2 whose voltages are inverted periodically.

The first and second drive selection signals SEL1 and SEL2 are signals whose potentials are inverted every vertical period, and have a high voltage and a low voltage during the same period.

The timing controller 142 inverts the potentials of the first and second drive selection signals SEL1 and SEL2 according to the external vertical synchronization signal Vsync.

The polarity controller 143 outputs the first polarity signal POL1 and the second polarity signal POL2 according to the potentials of the first and second drive selection signals SEL1 and SEL2.

The first polarity signal POL1 outputs a voltage waveform for driving a horizontal 2-dot inversion or vertical 2-dot inversion according to the potential of the first driving selection signal SEL1, and outputs the second polarity signal ( POL2 outputs a voltage waveform for driving the vertical 2-dot inversion or the horizontal 2-dot inversion according to the potential of the second drive selection signal SEL2.

For example, when the first drive selection signal SEL1 has a high potential, the first polarity signal POL1 is output as a waveform for horizontal two-dot inversion driving, and when the first potential selection signal SEL1 has a high potential, the first polarity signal POL1 is Output as a waveform for vertical two-dot inversion drive.

The first and second polarity signals POL1 and POL2 output from the polarity controller 143 are applied to the first and second data driver circuits 145a and 145b, respectively. The polarity of the image voltage DATA to be output from the two groups of data driver circuits 145 is controlled.

However, the voltage waveform of the first polarity signal POL1 applied to the data driver circuit 145a of the first group and the voltage waveform of the second polarity signal POL2 applied to the data driver circuit 145b of the second group are Since the first and second groups of data driving circuits 145a and 145b have different potentials, the regions of the liquid crystal panel 100 to which the image voltage DATA is applied are different from each other. It is driven by the 2-dot inversion method.

In summary, the first and second driving selection signals SEL1 and SEL2 are signals for determining an image voltage application method for applying an image voltage to the pixels R, G, and B. According to the high potential or the low potential of the first and second drive selection signals SEL1 and SEL2, one of the horizontal two-dot inversion and the vertical two-dot inversion is determined.

The determination is made by the polarity controller 143, and the polarity controller 143 adjusts and outputs the pulse widths of the first polarity signal POL1 and the second polarity signal POL2 according to the result.

The pulse width of the first and second polarity signals POL1 directly affects the polarities of the image voltages output from the first and second groups of data driving circuits 145 to the pixels R, G, and B. As the pulse width is wider, the image voltage output from the data driver circuits 145 of the first and second groups is output with the same polarity for a long time.

In the present invention, the pulse widths of the first and second polar signals POL1 and POL2 are selectively adjusted to one of one horizontal period and two horizontal periods, and, if the first and second polar signals POL1 and POL2 are pulse widths, respectively. When the output voltage is adjusted in one horizontal period, the image voltage will be output with the same polarity only during one horizontal period. When the pulse width is adjusted and output in two horizontal periods, the image voltage will be output with the same polarity during two horizontal periods. Thus, vertical two-dots and horizontal two-dots can be performed.

Although the liquid crystal panel 100 is not divided in the drawing, the liquid crystal panel 100 is divided into a first region and a second region, so that each of the first group of data driving circuits 145a and the second group of data driving circuits 145b is used. The image voltage DATA is applied through. In this case, when the pixels of the first area are applied with the image voltage in the horizontal two-dot inversion method, the pixels of the second area are applied with the image voltage in the vertical two-dot inversion method.

The first region may be divided into a left region of the liquid crystal panel 100, and the second region may be divided into a right region of the liquid crystal panel 100.

As described above, the liquid crystal panel 100 in which the first region and the second region are driven differently may be known in detail by the accompanying drawings.

FIG. 5A is a view illustrating the polarity change of the pixels arranged in the first region of the liquid crystal panel of FIG. 4 in units of frames, and FIG. 5B is a change of the polarity of the pixels arranged in the second region of the liquid crystal panel of FIG. 4 in units of frames. The figure shown.

The pixels R, G, and B arranged in the first region of the liquid crystal panel are driven in the vertical two-dot inversion scheme in the first frame. That is, the image voltage is equally applied to each of the two pixels R, G, and B adjacent up and down. Accordingly, each pixel row has a predominant polarity of bipolar or negative polarity.

In the second frame, the pixels R, G, and B are driven in a horizontal two-dot inversion scheme. In the third frame, the pixels R, G, and B are driven again in the vertical two-dot inversion scheme. In addition, in the fourth frame, the pixels R, G, and B are driven again in a horizontal two-dot inversion scheme.

As described above, vertical two-dot inversion driving or horizontal two-dot inversion driving is performed every two frames. The dominant or sequential left and right sequential phases cancel each other. In other words, vertical two-dot inversion and horizontal two-dot inversion are alternately used to prevent the same polarity from prevailing in up, down, left and right directions.

Meanwhile, as shown in FIG. 5B, the vertical two-dot inversion scheme and the horizontal two-dot inversion scheme are alternately applied to the pixels R, G, and B of the second region of the liquid crystal panel for each frame.

As described above, each pixel includes R, G and B corresponding to the first region and pixel R, G and B corresponding to the second region, respectively. By applying horizontal two-dot inversion driving alternately, vertical two-dot inversion and horizontal two-dot inversion are alternately applied to each frame for each region to cancel the polarity and the negative polarity as much as possible. It is possible to reduce the phenomenon in which a specific polarity prevails as a whole.

However, at the same time, the 2-dot inversion scheme applied to the first region and the second region should be applied differently. That is, by driving the first region and the second region in different two-dot inversion schemes, the same polarity is continuously prevented from occurring in the vertical or horizontal direction, and the first region and the second region are prevented. In addition, by applying the horizontal two-dot inversion method and the vertical two-dot inversion method alternately, it is possible to cancel the predominant polarity of the entire liquid crystal panel.

Therefore, the deterioration of image quality can be reduced because the polarity canceling effect is larger than in the past when only the vertical 2-dot inversion method or only the horizontal 2-dot inversion method is applied to the entire liquid crystal panel.

6 is an exemplary view showing waveforms of control signals for driving the liquid crystal display of FIG. 4 as shown in FIG.

First, in the pixels of the first region, the voltage waveform of the first polarity signal POL1 is determined according to the first drive selection signal SEL1 that transitions the high potential and the low potential LOW every frame. . More specifically, when the first drive selection signal SEL1 is at low potential, the first polarity signal POL1 is output as a voltage waveform for implementing a vertical two-dot inversion scheme. As shown, the low potential section of the first polarity signal POL1 corresponds to two horizontal periods.

When the first drive selection signal SEL1 has a high potential, the first polarity signal POL1 is output as a voltage waveform for implementing a horizontal two-dot inversion scheme. That is, in the horizontal two-dot inversion method, since the polarity of the image voltage is changed every one horizontal period, the first driving select signal SEL1 is reduced by half compared to the pulse width of the waveform output when the first drive selection signal SEL1 is at low potential.

In the same manner, the second polarity signal POL2 may be selectively selected as a voltage waveform for vertical two-dot inversion or a voltage waveform for horizontal two-dot inversion according to the potential of the second drive selection signal SEL2. Is output.

The pulse shape of the first drive selection signal SEL1 or the second drive selection signal SEL2 may be determined according to the vertical synchronization signal Vsync. The potential transition time points of the first and second drive selection signals SEL1 and SEL2 are synchronized with a rising edge of the vertical synchronization signal Vsync.

As described above, the liquid crystal display according to the present invention divides the liquid crystal panel into a plurality of regions, and drives the regions in different manners among the horizontal two-dot inversion method and the vertical two-dot inversion method, respectively. In this area, the horizontal two-dot inversion method and the vertical two-dot inversion method are alternately performed to reduce the phenomenon of characteristic polarity in the liquid crystal panel, thereby preventing deterioration of image quality of the liquid crystal display device.

Claims (11)

A liquid crystal panel divided into a first region and a second region; A plurality of pixels arranged in the liquid crystal panel; A timing controller which receives a vertical synchronization signal and an image voltage from the outside and outputs first and second drive selection signals for determining an image voltage application method together with the image voltage; A polarity controller for outputting a first polarity signal and a second polarity signal having different pulse widths according to the first and second drive selection signals; A first group of data driving circuits for applying an image voltage to the pixels corresponding to the first region and the pixels corresponding to the second region by different image voltage application methods according to the first and second polar signals; A liquid crystal display device comprising two groups of data driving circuits. The liquid crystal display of claim 1, wherein the image voltage application method is a vertical two-dot inversion method or a horizontal two-dot inversion method. 2. The liquid crystal display device according to claim 1, wherein the pulse widths of the first and second polarity signals vary according to potentials of the first and second drive selection signals, respectively. 4. The liquid crystal display device according to claim 3, wherein the pulse width of the first and second polarity signals is one horizontal period when the first and second drive selection signals are high potential, and the two horizontal periods are low frequency. . 5. The liquid crystal display device according to claim 4, wherein when the pulse width of the first and second polar signals is one horizontal period, the image voltage is applied to the pixels in a horizontal two-dot inversion manner. The liquid crystal display of claim 4, wherein when the pulse widths of the first and second polar signals are two horizontal periods, the image voltage is applied to the pixels in a vertical two-dot inversion manner. 2. The liquid crystal display device according to claim 1, wherein the first and second drive selection signals are shifted in potential every frame. 2. The liquid crystal display device according to claim 1, wherein the potential of the first and second drive selection signals is shifted in synchronization with the rising edge of the vertical synchronization signal. The method of claim 1, wherein a vertical two-dot inversion scheme and a horizontal two-dot inversion scheme are alternately applied to each pixel corresponding to the first region and the second region of the liquid crystal panel. LCD display device. The liquid crystal display of claim 1, wherein a horizontal two-dot inversion scheme and a vertical two-dot inversion scheme are alternately applied to each of the frames in the first and second regions of the liquid crystal panel. 2. The liquid crystal display of claim 1, wherein the voltage polarity of the pixels in the first and second regions of the liquid crystal panel is changed every two frames by the vertical two-dot inversion method or the horizontal two-dot inversion method.

Images