KR100898789B1 - A method for driving liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a liquid crystal display device, comprising: a gate driver for driving a gate line of a liquid crystal panel, a source driver constituting a data line of the liquid crystal panel, an image signal and a control signal to receive a gate driver and a source driver A liquid crystal display device comprising a timing controller for processing timing of the liquid crystal display device, wherein the dot inversion method and the interlaced scanning method of the liquid crystal panel are used together.

Dot inversion, interlaced

Description

A method for driving liquid crystal display device

1A to 1B are explanatory diagrams showing the structure of the data voltage polarity of the dot inversion method of the conventional liquid crystal display device.

2A to 2D are explanatory diagrams showing the structure of the data voltage polarity for the interlaced scanning method of the liquid crystal display according to the present invention.

3 is an explanatory diagram for data transmission and control signals from a liquid crystal panel to a driver;

4 is an explanatory diagram showing a structure of data voltage polarity on an actual screen;

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a liquid crystal panel in a liquid crystal display device, and more particularly, to a method for driving a liquid crystal display device for driving dot inversion in an interlaced scan form in order to obtain high image quality.

It has been only 30 years since the liquid crystal display was put into use as a display device, but it began to be used as an electronic calculator and a clock display unit, and has been applied to machinery and electronic notebooks. It is applied to various types of automatic navigation system.

Among the many flat panel displays currently developed, the liquid crystal display device injects liquid crystal between two glass substrates after bonding a glass substrate on which a thin film transistor array (TFT-Array) and a glass substrate on which a color filter is formed so as to maintain a constant gap. After the liquid crystal panel is formed, a driving system is provided around the liquid crystal panel to apply a signal to the liquid crystal panel and to control the signal.

Here, a plurality of gate lines and data lines are intersected on the thin film transistor array substrate to define a pixel region having a matrix shape, and a pixel electrode for driving each pixel in each pixel region and a driving signal of the gate line. The thin film transistor is arranged to apply the image signal of the data line to each pixel electrode.

On the glass substrate on which the color filter is formed, a black matrix layer is formed to block light in portions other than the pixel region, and an RGB color filter layer is formed in each pixel region. The common electrode is formed on the entire surface of the substrate including the filter layer.

When the two substrates are bonded to each other and a liquid crystal layer is formed between the two substrates, a liquid crystal capacitive capacitance C _LC is formed between the pixel electrode and the common electrode, and a gate line adjacent to the pixel electrode overlaps to separate storage. Lines are formed to form a capacitive capacitance C _st .

A column driving integrated circuit chip for sequentially applying a driving signal to the gate line (hereinafter referred to as a 'gate driver') and a line driving integrated circuit chip for applying a data signal to the data line (Line) Driving Integrated Circuit Chip (hereinafter referred to as a "source driver"), and a timing controller for applying various control signals and voltages to the gate driver and the source driver.

The timing controller receives various signals (RGB image signal, synchronization signal (Vsync, Hsync), clock signal (CLK), etc.) and applies a data signal to the corresponding data line through the source driver, and through the gate driver A selection pulse is applied to the gate line so that the thin film transistor is turned on. As such, the data signal voltage applied through the data line is charged in the liquid crystal capacitor C _LC and the sustain capacitor C _st while the thin film transistor is turned on.

When the thin film transistor is turned off by the selection pulse applied to the gate line, the voltage charged in the liquid crystal capacitor C _LC and the holding capacitor C _st is turned on for the voltage applied to the next data signal. It stays until (On).

As described above, the thin film transistor transmits the corresponding data signal voltage to the pixel electrode while repeatedly turning on and off, and the liquid crystal is driven by the voltage to display the screen on the liquid crystal panel.                         

In addition, the liquid crystal display device uses a polarity inversion method to obtain a high image quality as an image display device using liquid crystal, and the polarity inversion method includes frame inversion, line inversion, and column inversion. (column inversion) and dot inversion method.

The frame inversion method applies a polarity of the data voltage applied to the liquid crystal with respect to the common electrode voltage in the unit of frame. If a positive polarity data voltage is applied to the odd frame, the even frame ( In this case, a negative data voltage is applied to an odd frame.

Such a frame inversion method has the advantage of low current consumption during switching, but is sensitive to flicker due to asymmetry of transmittance asymmetry of positive and negative polarity, It has the disadvantage of being very vulnerable to crosstalk due to interference.

The line inversion scheme is a polarity inversion scheme commonly used for low resolutions (VGA and SVGA), and applies a data voltage such that the polarity of the pixel is changed in units of horizontal lines. If a negative polarity data voltage is applied to the and even lines, the polarity of the voltage is reversed in the next frame.

In this line inversion method, since data voltages of opposite polarities are applied between adjacent lines, the variation in luminance between lines is reduced by the spatial averaging, and the flicker phenomenon is reduced compared to the frame inversion, and the voltages of opposite polarities are distributed in the vertical direction. Therefore, the coupling phenomenon between the data is canceled out so that the vertical crosstalk compared to the frame inversion is small. However, in the horizontal direction, voltages of the same polarity are distributed to generate horizontal crosstalk, and the number of switching repetitions increases compared to frame inversion, thereby increasing the current consumption.

The column inversion method is a method in which the polarity of the applied data voltage is the same in the vertical direction and is applied in the opposite polarity in the horizontal direction, that is, the polarity is changed in the vertical line unit as opposed to the line inversion method.

In the column inversion method, the flicker phenomenon is smaller than the frame inversion and the horizontal crosstalk is smaller than the frame inversion by the spatial averaging method as in the line inversion method.

However, a high voltage column drive IC should be used because data voltages having opposite polarities between adjacent lines must be applied in a vertical direction with respect to the common electrode voltage.

Lastly, in the dot inversion scheme, polarities of data voltages between adjacent pixels are reversed in all directions of up, down, left, and right directions. If a data voltage is applied with a polarity and a neighboring pixel has a structure of opposite polarity, a voltage opposite to the polarity of the pixel is applied in the next frame.

Referring to the accompanying drawings, a driving method of a liquid crystal display device driven by a conventional dot inversion method which is widely used in the best image quality and high resolution (XGA, SXGA, UXGA) of the polarity inversion method is as follows.                         

1A to 1B are explanatory diagrams of data voltage polarities of a first frame and a second frame for explaining a dot inversion scheme of a conventional liquid crystal display.

As described above, in the liquid crystal panel in which the plurality of gate lines and the plurality of data lines are arranged in a direction perpendicular to each other to form pixel regions in a matrix form, the data voltage polarities between adjacent pixels are reversed in all directions of up, down, left and right. Apply the data voltage. In the next frame, the polarity of each pixel area is opposite to that of the previous frame.

1A is an explanatory diagram of data voltage polarity of a first frame for explaining a dot inversion scheme of a conventional liquid crystal display.

In the first frame, a positive data voltage is applied to an odd data line and a negative data voltage is applied to an even data line when driving an odd gate line. When the even-numbered gate line is driven, a negative data voltage is applied to the odd-numbered data line and a positive data voltage is applied to the even-numbered data line.

FIG. 1B is a diagram illustrating data voltage polarity of a second frame for explaining a dot inversion scheme of a conventional liquid crystal display.

 In the second frame, which is the next frame after the first frame, the odd-numbered data line is applied with a negative data voltage and the positive-numbered data line is applied to the odd-numbered data line when driving the odd-numbered gate line as opposed to the driving method of the first frame. A positive data voltage is applied. When the even-numbered gate line is driven, a positive data voltage is applied to the odd-numbered data line and a negative data voltage is applied to the even-numbered data line.

However, the driving method of the conventional dot inverted liquid crystal display device has the following problems. First, the polarity variation of the pixel that charges when the gate line is sequentially driven by the dot inversion method and the polarity variation of the charging voltage are the same, which is the same as the polarity variation of the pixel. As the polarity of the charging voltage is also changed, flicker occurs.

Second, since the polarity is changed in one horizontal unit, power consumption due to the polarity change is increased.

Third, when one gate line is turned on, a plurality of polarity data are simultaneously transmitted so that the bias voltage of the source driver for driving the liquid crystal panel, that is, the analog voltage level (Level) Cannot be lowered.

Disclosure of Invention The present invention is to solve the above-mentioned problems. The liquid crystal display device of which a dot inversion method is driven by an interlaced scanning method prevents flicker, reduces power consumption, and lowers an analog voltage level. The purpose is to provide a driving method.

According to an aspect of the present invention, there is provided a method of driving a liquid crystal display device, including a gate driver for driving a gate line of a liquid crystal panel, a source driver for driving a data line of the liquid crystal panel, and a gate driver and a source driver. A liquid crystal display device comprising a timing controller for transmitting a data signal and a control signal, wherein the even frame and the odd gate line are driven by an even gate line in a dot frame or a column frame driven by a dot inversion method. It is divided into an odd frame driven by and to drive an even gate line or an odd gate line by using an interlaced scanning method so that only the even frame or the odd frame is driven.

The even frame and the odd frame are combined into a dot frame, and the dot frame represents a data voltage polarity of a dot inversion method.

The even and odd frames are combined to form a column frame. The column frame represents the data voltage polarity of the column inversion method, and since the polarity of the first data of the even and odd frames is the same, the polarity signal is divided into one vertical period. The driving method of the liquid crystal display device characterized by applying.

The dot frame and the column frame are repeatedly formed every frame.

It is driven by dot inversion method and column inversion method through source driver,

A method of driving a liquid crystal display device comprising a frame driven by a dot inversion method and a frame driven by a column inversion method to be repeatedly formed every frame.

Hereinafter, a driving method of the liquid crystal display according to the first, second, and third embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the liquid crystal display according to the present invention, the glass substrate on which the thin film transistor array is formed and the glass substrate on which the color filter is formed are bonded to each other to maintain a constant distance, and then a liquid crystal is injected between two glass substrates to form a liquid crystal panel. A driving system is provided in the periphery of the panel and includes a circuit unit for applying a signal to the liquid crystal panel and controlling the signal.

The thin film transistor array substrate has a plurality of gate lines and data lines intersected to define a pixel area in a matrix form, and includes a thin film transistor and a pixel electrode in each pixel area.

On the glass substrate on which the color filter is formed, a black matrix layer is formed to block light in portions other than the pixel region, and each pixel region includes an RGB color filter layer.

A gate driver for driving the gate line of the liquid crystal panel, a source driver for driving the data line of the liquid crystal panel, and various signals (RGB image signal, synchronization signal (Vsync, Hsync), clock signal (CLK), etc.) are inputted. And a timing controller which processes timing signals of the gate driver and the source driver.

In the driving method of the liquid crystal display of the present invention, the dot inversion method is as described above, and the interlaced scanning method is to divide the gate line into an odd-numbered gate line and an even-numbered gate line in one frame, and in the odd frame in one frame. The gate line and the even gate line are alternately driven.                     

2A to 2D are explanatory diagrams of data voltage polarity of the interlaced scanning method according to the dot inversion method of the present invention, which will be described in more detail with reference to the accompanying drawings.

The dot inversion method applies a data voltage such that the data voltage polarity between adjacent pixels is reversed in all directions of up, down, left, and right of one pixel, and turns on the thin film transistor by crossing the gate line one line by the interlaced scanning method. Turn (Turn On).

FIG. 2A is a first even frame of data voltage polarity in which a gate line is turned on for every odd line of one frame indicating a data voltage polarity of a dot inversion scheme.

When the data signal is applied to the liquid crystal panel by the source driver and the gate line of g (n + 1) is applied to the thin film transistor by the gate driver, the gate line of g (n + 1) is framed. The data signal is displayed on the screen. Next, when a new data signal is applied to the liquid crystal panel, the gate line of g (n + 3) becomes the gate line of g (n + 3) when the on voltage is applied to the thin film transistor by the gate driver. The signal is displayed.

In this interlaced frame, the odd-numbered data lines d (1), d (3), ..., when driving even-numbered gate lines g (n + 1), g (n + 3), ... d (n) is applied with a data voltage of negative polarity and data of positive polarity is applied to even-numbered data lines d (2), d (4), ..., d (n + 1). Voltage is applied. The odd-numbered gate lines g (n), g (n + 2), ... are not driven.

FIG. 2B is a first odd frame of data voltage polarity in which the gate line is turned on for every odd line of one frame showing the data voltage polarity of the dot inversion method.

When the data signal is applied to the liquid crystal panel by the source driver and the gate line of g (n) is applied to the thin film transistor by the gate driver, the gate line of g (n) is applied to the frame by the gate driver. Is displayed. Next, when a new data signal is applied to the liquid crystal panel, the gate line of g (n + 2) becomes the gate line of g (n + 2) when the on voltage is applied to the thin film transistor by the gate driver. The signal is displayed.

In the frame interlaced in this manner, the odd-numbered data lines d (1), d (3), ..., d (when driving the odd-numbered gate lines g (n), g (n + 2), ... n)) is applied with a data voltage of positive polarity and a data voltage of negative polarity is applied to even-numbered data lines d (2), d (4), ..., d (n + 1). Is approved. The even-numbered gate lines g (n + 1), g (n + 3), ... are not driven.

FIG. 2C is a second even frame of the data voltage polarity in which the gate line is turned on for each odd line of the frame in which the data voltage polarity of the dot inversion scheme is the opposite polarity of the first even frame.

As in the first even frame, a data signal is applied to the liquid crystal panel by the source driver, and only an even gate line is applied to the thin film transistor by an on voltage.

In the interlaced frame in this manner, the odd-numbered data lines d (1), d (3), ... when driving even-numbered gate lines g (n + 1), g (n + 3), ... d (n) is applied with a positive polarity data voltage and a negative polarity is applied to even-numbered data lines d (2), d (4), ..., d (n + 1). The data voltage is applied. The odd-numbered gate lines g (n), g (n + 2), ... are not driven.

FIG. 2D is a second odd frame having a data voltage polarity in which a gate line is turned on for every odd line of the frame having the opposite polarity of the first odd frame showing the data voltage polarity of the dot inversion scheme.

As in the first odd frame, a data signal is applied to the liquid crystal panel by the source driver, and only the odd-numbered gate lines are applied to the thin film transistor by the gate driver.

Thus, when driving the odd-numbered gate lines g (n), g (n + 2), ... with the second odd frame, the odd-numbered data lines d (1), d (3), ..., d (n)) is a data voltage of positive polarity is applied and a data voltage of negative polarity is applied to even-numbered data lines d (2), d (4), ..., d (n + 1). Is applied. The even-numbered gate lines g (n + 1), g (n + 3), ... are not driven.

In this way, one frame can be divided into two even / odd frames, and each frame is divided into two frames.

3 shows the data voltage polarity by the interlaced scanning method according to the first embodiment of the present invention.

The interpolation scanning method combines the first even frame and the first odd frame into one to form one frame, and the data voltage is applied by applying the data voltages so that the polarities of the data voltages of the adjacent pixels are reversed in all directions of up, down, left, and right of one pixel. The frame is constructed. The frames thus merged are referred to as dot frames hereinafter.

By driving the data voltage polarity as the dot inversion method by the dot frame and doubling the frequency when transmitting the data signal from the liquid crystal display device to the timing controller, the method of the first embodiment can be applied without loss of data. Do.

4A illustrates data transmission and control signals from the timing controller to the driver according to the second embodiment of the present invention.

In general screen, there is little change of data of one frame and data of next frame and the data is similar. When data is transmitted from the timing controller to the driver, the even and odd lines are horizontally divided to transmit the data of the even lines in one frame and the data of the odd lines in the next frame, and the data of the odd lines in the next frame. Do not transmit even lines of data.

In the gate driver, even-numbered gate lines are sequentially turned on for data of one frame to match the correct pixels, and odd-numbered gate channels are sequentially turned on for data of the next frame. Match the correct pixel. The even and odd frames of data transmitted make up one complete frame.

One completed frame as shown above is illustrated in FIG. 4B. 4B illustrates the data voltage polarity by the interlaced scanning method according to the second embodiment of the present invention.

As described above, a frame in which the data voltage is applied to combine the first even frame and the second odd frame by the interlaced scan method into one to form one frame and apply the same polarity in the vertical direction and the opposite polarity in the horizontal direction is combined. It is composed. The frames thus merged are referred to as column frames hereinafter.

As described above, while the thin film transistor is turned on by the interlaced scanning method, it corresponds to one frame having one horizontal period, and one frame is an odd frame of odd-numbered gate line driving and an even frame of even-numbered gate line driving. It is longer than one horizontal period to sequentially drive the gate line.

The data transmission frequency and clock frequency of the liquid crystal panel are halved than the data transmission frequency and clock frequency which sequentially drive the gate lines because only one of the two data is transmitted by dividing into even and odd gate lines in one frame. .

On the other hand, the data polarity between even-numbered data lines of even frames according to the first embodiment is all negatively the same, and the polarity of data of odd-numbered data lines of the second frame is negative between odd-numbered lines (- Since the polarity is the same, the polarity signal should be applied in one vertical period accordingly.

FIG. 5 illustrates a method of driving a frame on the actual screen in which the column frame and the dot frame of the first embodiment are formed.

As shown in Fig. 5, when the first dot frame is displayed, the next frame is displayed with the second column frame, and the next frame is displayed with the third dot frame, the next frame is displayed with the fourth column frame, and again. It is repeatedly displayed in the first dot frame.

The first dot frame is formed by combining the first even frame and the first odd frame, and the second column frame is formed by combining the first odd frame and the second even frame, and the third dot frame is formed by the second even frame and the first odd frame. Two odd frames are combined to form a fourth column frame, and a second odd frame and a first even frame are formed to combine.

The driving method of the liquid crystal display according to the third embodiment of the present invention will be described in detail as follows.

The driving method uses the dot inversion method and the column inversion method without using the interlaced scanning method different from those of the first and second embodiments.

As in the conventional manner, the gate driver causes a plurality of gate lines to be driven sequentially per one horizontal sync signal. On the other hand, the source driver configures the data voltage polarity of the dot inversion method that supplies the data signal such that the data lines are inverted in each pixel every time the gate line is driven, and when the gate lines are sequentially driven in the next frame. Each data line constitutes a data voltage polarity of a column inversion method for supplying a data signal such that polarity is inverted for each data line.

In this configuration, the polarity signal is configured such that the dot polarity and the column polarity are alternately applied to the data voltage polarity in every frame, and thus the polarity signal can be configured as shown in FIG. 4.

Accordingly, the four frames may be repeatedly rotated every 60 Hz as shown in FIG. 4 by using the dot inversion method and the column inversion method without using the interlaced scanning method.

As described above, the driving method of the liquid crystal display device of the present invention has the following effects.

That is, the pixel region is driven in a structure in which the four frames are repeatedly rotated every 60 Hz by the dot inversion method and the interlaced scanning method and the dot inversion method and the column inversion method, thereby eliminating a specific flicker pattern itself.

The interlaced scanning method can reduce the analog power consumption because the polarity of data is changed by 1 vertical unit, and one frame is divided into even and odd numbers so that only one data is transmitted. Digital power consumption due to data transmission can be reduced.

In addition, the image quality may deteriorate because the driving frequency is reduced by half, but the frequency on the actual screen is driven at the same frequency so that the image quality does not deteriorate. The method can be applied without loss of data.

Claims (9)

A gate driver for driving the gate line of the liquid crystal panel; A source driver for driving data lines of the liquid crystal panel; A liquid crystal display comprising a timing controller configured to transfer data signals and control signals of the gate driver and the source driver. In one dot frame or column frame driven by a dot reversal method, it is divided into an even frame driven by an even gate line and an odd frame driven by an odd gate line, and interlaced so that only the even frame or odd frame is driven. A driving method of a liquid crystal display device comprising driving an even gate line or an odd gate line using a scanning method. delete The method of claim 1, wherein the dot frame represents a data voltage polarity of a dot inversion method. delete The driving method of claim 1, wherein the column frame represents a data voltage polarity of a column inversion method. delete The method of claim 1, wherein the dot frame and the column frame are repeatedly formed every frame. A gate driver for driving the gate line of the liquid crystal panel; A source driver for driving data lines of the liquid crystal panel; A liquid crystal display comprising a timing controller configured to transfer data signals and control signals of the gate driver and the source driver. A liquid crystal display comprising a frame driven by a dot inversion method and a frame driven by a column inversion method and repeatedly formed every frame, and driven by a dot inversion method and a column inversion method through the source driver. Method of driving the device. delete

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