KR20080011889A - Liquid display device - Google Patents

Abstract

An LCD is provided to remove a flickering phenomenon in a one-dot inversion driving type vulnerable to the flickering phenomenon, thereby improving the picture quality of the LCD. An LCD panel(110) displays an image according to a first driving mode and a second driving mode. A signal controller(120) outputs a gate clock signal, and a mode selection signal for selecting the first driving mode or the second driving mode. A data driver(140) supplies a first data voltage and a second data voltage to the LCD panel. The first data voltage corresponds to the first driving mode in response to the activated mode selection signal, and a second data voltage corresponds to the second driving mode in response to the inactivated mode selection signal. A voltage generator(150) supplies a first gate-on voltage and a second gate-on voltage to a gate driver(130). The first gate-on voltage corresponds to the first driving mode in synchronization with the gate clock signal. The second gate-on voltage corresponds to the second driving mode and has a different level and a different pulse width from the first gate-on voltage. The gate driver supplies the first gate-on voltage and the second gate-on voltage to the LCD panel.

Description

 Liquid crystal display device

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

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

2 is a diagram illustrating a one dot inversion driving method of the liquid crystal display of the present invention.

3 is a view showing a two-dot inversion driving method of the liquid crystal display of the present invention.

4 is a diagram illustrating a waveform of a gate on voltage according to an embodiment of the present invention for removing the flicker phenomenon.

5 is a diagram illustrating a waveform of a gate on voltage according to another exemplary embodiment of the present invention for eliminating flicker.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device for displaying an image, and more particularly, to a liquid crystal display device capable of removing a flicker phenomenon in a single dot driving method.

In general, the liquid crystal display includes a liquid crystal layer having dielectric anisotropy interposed between two display panels. The desired image is obtained by applying an electric field to the liquid crystal layer and adjusting the intensity of the electric field to adjust the transmittance of light passing through the liquid crystal layer.

The liquid crystal display device is typical among portable flat panel liquid crystal display devices, and among these, TFT-LCD using a thin film transistor as a switching element is widely used.

On the other hand, the liquid crystal layer deteriorates the liquid crystal material included in the liquid crystal layer when the electric field in the same direction is continuously applied. Therefore, it is necessary to drive by inverting the polarity of the gray scale voltage with respect to the common voltage.

For this reason, a frame inversion method (FIM) that inverts the polarity on a frame-by-frame basis and a dot inversion method (DIM) on a line-by-line basis are adopted to invert the TFT-LCD. It is applied to production.

However, the dot inversion driving method is good in terms of horizontal crosstalk, but the problem of flickering is weak. This is because a TFT-LCD is often used in a graphic environment such as a computer, and thus often displays a dot screen configuration.

In general, flickering refers to image quality blur when a difference in transmittance between two polarities occurs in a process of periodically inverting the charging polarity of the liquid crystal to the positive (+) and the negative (-) polarities.

This flickering phenomenon occurs remarkably when a specific pattern is expressed by one tote and the one-dot inversion driving method is applied, thereby greatly reducing the display quality of the liquid crystal display.

Accordingly, an object of the present invention is to provide a liquid crystal display device which can improve display quality by removing flickering.

The liquid crystal display device of the present invention for achieving the above technical problem includes a liquid crystal display panel, a signal controller, a data driver, a gate driver and a voltage generator. The liquid crystal display panel displays an image according to the first driving mode and the second driving mode. The signal controller outputs a gate clock signal and a mode selection signal for selecting the first driving mode or the second driving mode. The data driver may include a first data voltage corresponding to the first driving mode and a second data voltage corresponding to the second driving mode in response to the deactivated mode selection signal in response to the activated mode selection signal. Provided by the display panel. The voltage generator includes a first gate on voltage corresponding to the second driving mode and a second gate corresponding to the second driving mode and a level and pulse width different from the first gate on voltage in synchronization with the gate clock signal. Generate an on voltage. The gate driver provides a first gate on voltage and the second gate on voltage to the liquid crystal display panel.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. In addition, in the following description, numerous specific details, such as specific processing flows, are described to provide a more general understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. Incidentally, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

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

1 is a block diagram illustrating a liquid crystal display device 100 according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display 100 according to an exemplary embodiment of the present invention includes a display panel 110, a signal controller 120, a gate driver 130, and a data driver 140.

The display panel 110 may include a plurality of gate lines GL extending in a first direction, a plurality of data lines DL extending in a second direction orthogonal to the first direction, and gate lines GL. A thin film transistor (hereinafter, referred to as TFT) connected to the data lines DL and a pixel electrode connected to the TFT are included.

The plurality of gate lines GL1 to GLn extend substantially in the row direction and are substantially parallel to each other. The plurality of data lines DL1 to DLm are insulated from the plurality of gate lines and extend in a substantially column direction. They are also almost parallel to each other.

The plurality of gate lines GL1 to GLn sequentially receive gate voltages including a gate on voltage VON and a gate off voltage Voff output from the gate driver 130.

The display panel 110 may include a plurality of dots arranged in a matrix. Each of the plurality of dots is a minimum unit for implementing an image on the display panel. The display panel 110 according to the present invention displays an image according to a first driving mode and a second driving mode.

FIG. 2 is a diagram showing a one dot inversion driving method of the liquid crystal display of the present invention, and FIG. 3 is a diagram showing a two dot inversion driving method of the liquid crystal display of the present invention.

2 and 3, the first driving mode is a one dot inversion driving method, and the second driving mode is a two dot inversion driving method. Specifically, the first driving mode inverts one dot at a fixed position every frame or line as one unit. The second driving mode inverts two adjacent dots in a fixed position every frame or line as a unit.

The signal controller 120 receives R, G, and B data, a vertical sync signal Vsync, a horizontal sync signal Hsync, a data enable signal DE, and a main clock signal from an external graphic controller (not shown). The first control signal CNT1 and the second control signal CNT2 for driving the data driver and the gate driver are output.

The first control signal CONT1 may include a vertical synchronization start signal STV indicating the start of the output of the gate-on voltage VON, a clock signal CPV that controls the output timing and the output voltage of the gate-on voltage VON, and the like. Include. Here, the gate-on voltage VON is maintained for one period (1H: 1 horizontal period) of the clock signal. That is, the pulse width of the gate-on voltage VON is maintained for a period corresponding to one period of the clock signal. That is, the pulse width of the gate-on voltage VON increases or decreases according to a time corresponding to one cycle of the clock signal CPV.

Meanwhile, the signal controller 120 included in the liquid crystal display device 100 according to the present invention may vary one cycle 1H of the clock signal CPV according to the driving mode of the display panel 110 to change the gate driver ( 130).

In detail, when the display panel 110 displays an image in the first driving mode, the signal controller 120 increases the time corresponding to one period of the clock signal CPV. That is, the gate driver 130 is provided to the gate driver 130 by increasing the time corresponding to one period of the clock signal CPV in the second driving mode.

Accordingly, the gate driver 130 is applied to the display panel 110 by increasing the pulse width of the gate-on voltage by the increased time.

The second control signal CONT2 is applied to the horizontal synchronization start signal STH indicating the start of the transmission of the image data DAT, the load signal ROAD to apply the corresponding data voltage to the data line DL, and the common voltage VCOM. And an inverted signal RVS and a data clock signal HCLK for inverting the polarity of the data voltage.

In addition, the signal controller 120 may output a mode selection signal POL for outputting a first data voltage corresponding to the first driving mode and a second data voltage corresponding to the second driving mode output from the data driver 140. Outputs

Specifically, when the data driver 140 receives a mode selection signal activated by the signal controller 120, for example, logic 'H' or logic 'L', the data driver 140 may enter the first driving mode. The first data voltage corresponding to the same is provided to the display panel 110.

On the other hand, when the data driver 140 receives a mode selection signal, for example, a logic level 'L' or a logic level 'H', which is deactivated from the signal controller 120, the data driver 140 may enter the second driving mode. The second data voltage corresponding to the same is provided to the display panel 110.

The data driver 140 stores the R, G, and B data from the signal controller 120, and when a load signal from the signal controller 120 is applied, selects a voltage corresponding to each data and displays the display panel. The data voltage for transmitting the voltage is output to 140.

As described above, the data driver 140 displays the first data voltage corresponding to the first driving mode or the second data voltage corresponding to the second driving mode in response to the mode selection signal from the signal controller. ) Is applied to the data lines DL.

The polarity of the first data voltage is inverted for each frame and line using one dot belonging to a specific pattern (specific dot group) formed on the display panel 110 as one unit.

The polarity of the second data voltage is inverted for each frame and line using two dots belonging to a specific pattern (specific dot group) formed on the display panel 110 as one unit. Here, the two dots are composed of two dots adjacent in the column direction (2 * 1) or in the row direction (1 * 2).

The gate driver 130 receives the first control signal CONT1 and the second control signal CONT2 provided from the control unit 120 and receives gate voltages VON1, VON2, and VOFF from the gate lines GL1 to GLn. In order).

The gate voltages VON1, VON2, and VOFF include a first gate on voltage VON1, a second gate on voltage VON2, and a gate off voltage VOFF.

The first gate-on voltage VON1 and the second gate-on voltage VON2 turn on a plurality of switching elements formed on the display panel so that the first data voltage and the second data voltage correspond to the corresponding pixels. To be delivered.

The gate off voltage VOFF turns off the plurality of switching elements to maintain each data voltage transferred to each pixel until a next gate on voltage is provided.

The voltage generator 150 generates a voltage required to drive the display panel 110, for example, gate voltages VON1, VON2, and VOFF, a gray voltage, a common voltage, and the like. The gate driving voltage VON / VOFF is provided to the gate driver, the gray voltage is provided to the data driver, and the common voltage Vcom is provided to the display panel.

The voltage generator 150 included in the liquid crystal display device 100 according to the present invention is synchronized with the first gate-on voltage VON1 in synchronization with the gate clock signal CPV included in the first control signal CONT1. The second gate on voltage VON2 is transferred to the gate driver 130.

In detail, when the display panel displays an image according to the first driving mode, that is, the one dot inversion driving method, the voltage generator 150 outputs the first gate-on voltage VON1. When the display panel displays an image according to the first driving mode, that is, the 1 dot inversion driving method, the voltage generator 150 outputs the second gate-on voltage VON2. In this case, the voltage level of the first gate on voltage is set higher than the voltage level of the second gate on voltage.

Hereinafter, the liquid crystal display of the present invention having the above components will be described in detail with reference to the accompanying drawings.

4 is a diagram illustrating a waveform of a gate on voltage according to an embodiment of the present invention for removing the flicker phenomenon.

As shown in FIG. 4, in the liquid crystal display 100 according to the exemplary embodiment, gate-on voltages having different voltage levels are provided to the display panel according to the driving method of the display panel 110. That is, in the one-dot inversion driving method in which the flicker phenomenon is prominent, the display panel 110 has a first gate-on voltage VON1 higher than the voltage level of the second gate-on voltage VON2 provided in the two-dot inversion driving method. Is applied.

 In this way, the flicker phenomenon can be further reduced by ensuring a stable charge amount for each pixel in the one-dot inversion driving method in which the charge amount charged in the pixel is fluctuated.

5 is a diagram illustrating a waveform of a gate on voltage according to another exemplary embodiment of the present invention for eliminating flicker.

Referring to FIG. 5, in another exemplary embodiment of the present invention, a pulse width of each gate-on voltage applied according to each driving scheme is differentially set and provided to the display panel.

That is, in the one dot inversion driving method, the first gate on voltage VON1 longer than the pulse width of the second gate on voltage VON2 provided in the two dot inversion driving method is applied to the display panel 110.

By doing so, the flicker phenomenon is reduced by ensuring a stable charge amount for each pixel in the one-dot inversion driving method in which the charge amount charged in the pixel is fluctuated.

On the other hand, the pulse width of the gate-on voltage only needs to change the pulse width of the gate clock signal (CPV) through the logic circuit of the signal controller 120, it can be implemented simply without additional circuit configuration.

According to the liquid crystal display of the present invention as described above, in the one-dot inversion driving method, the first gate-on voltage VON1 higher than the voltage level of the second gate-on voltage VON2 provided in the two-dot inversion driving method is the above-mentioned. It is applied to the display panel.

In addition, a first gate on voltage VON1 longer than a pulse width of the second gate on voltage VON2 provided in the two dot inversion driving method is applied to the display panel.

Therefore, by eliminating the flickering phenomenon in the one-dot inversion driving method that is vulnerable to the flickering phenomenon, the display quality of the liquid crystal display device can be improved.

As described above, the optimum embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the present invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (5)

A liquid crystal display panel displaying an image according to the first driving mode and the second driving mode; A signal controller configured to output a gate clock signal and a mode selection signal for selecting the first driving mode or the second driving mode; Providing a first data voltage corresponding to the first driving mode in response to the activated mode selection signal and a second data voltage corresponding to the second driving mode in response to the deactivated mode selection signal to the liquid crystal display panel A data driver; A first gate on voltage corresponding to the first driving mode and a second gate on voltage corresponding to the second driving mode and having a level and a pulse width different from the first gate on voltage are generated in synchronization with the gate clock signal. A voltage generator to provide the gate driver; And And a gate driver configured to provide the first gate on voltage and the second gate on voltage to the liquid crystal display panel. The method of claim 1, And the first driving mode is a one dot inversion driving method, and the second driving mode is a two dot inversion driving method. The method of claim 2, And the first gate on voltage is higher than a voltage level of the second gate on voltage. The method of claim 2, And a pulse width of the first gate on voltage is longer than a width of the second gate on voltage. The method of claim 4, wherein And one period of the gate clock signal corresponding to the first gate on voltage is longer than one period of the gate clock signal corresponding to the second gate on voltage.

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