KR20050065825A - Apparatus for driving and method of liquid crystal display device the same - Google Patents

Abstract

The present invention relates to a driving apparatus for a liquid crystal display device and a driving method thereof capable of selectively switching a normally white mode and a normally black mode according to a driving method of the liquid crystal display device.

The driving apparatus of the liquid crystal display according to the present invention comprises: a gamma voltage generator for generating a plurality of gamma voltages having different voltages; A digital-to-analog converter array supplied with the plurality of gamma voltages and selecting the gamma voltage corresponding to digital input data; A mode selection unit for generating a mode selection signal; And a gamma voltage converter in which the gamma voltages are aligned in one of a forward direction and a reverse direction and supplied to the input terminals in response to the mode selection signal.

A method of driving a liquid crystal display according to an exemplary embodiment of the present invention includes generating a plurality of gamma voltages having different voltages; Selecting the gamma voltage supplied with a plurality of gamma voltages through a plurality of input terminals and corresponding to digital input data; Generating a mode selection signal; And aligning the gamma voltages in one of a forward direction and a reverse direction to the input terminals in response to the mode selection signal.

Description

A driving device of a liquid crystal display and a driving method thereof {APPARATUS FOR DRIVING AND METHOD OF LIQUID CRYSTAL DISPLAY DEVICE THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a driving device of a liquid crystal display device and a method of driving the liquid crystal display device capable of selectively switching a normally white mode and a normally black mode according to a driving method of the liquid crystal display device.

Conventional liquid crystal display devices display an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display includes a liquid crystal panel in which liquid crystal cells are arranged in a matrix and a driving circuit for driving the liquid crystal panel. In the liquid crystal panel, the gate lines and the data lines are arranged to cross each other, and the liquid crystal cells are positioned in an area where the gate lines and the data lines cross each other. The liquid crystal panel is provided with pixel electrodes and a common electrode for applying an electric field to each of the liquid crystal cells. Each of the pixel electrodes is connected to any one of the data lines via source and drain terminals of a thin film transistor, which is a switching element. The gate terminal of the thin film transistor is connected to any one of the gate lines through which the pixel voltage signal is applied to the pixel electrodes of one line. The driving circuit includes a gate driver for driving the gate lines, a data driver for driving the data lines, and a common voltage generator for driving the common electrode. The gate driver sequentially supplies the scanning signals to the gate lines to sequentially drive the liquid crystal cells on the liquid crystal panel by one line. The data driver supplies a pixel voltage signal to each of the data lines whenever a gate signal is supplied to any one of the gate lines. The common voltage generator supplies a common voltage signal to the common electrode. Accordingly, the liquid crystal display displays an image by adjusting light transmittance by an electric field applied between the pixel electrode and the common electrode according to the pixel voltage signal for each liquid crystal cell. The data driver and the gate driver are integrated into a plurality of integrated circuits (hereinafter, referred to as ICs). Each of the integrated data drive IC and the gate drive IC are mounted on a tape carrier package (hereinafter referred to as TCP) and connected to a liquid crystal panel using a tape automated bonding (TAB) method, or a chip on glass ) Is mounted on the liquid crystal panel.

1 is a block diagram showing a detailed configuration of a data driver according to a liquid crystal display of the prior art.

Referring to FIG. 1, the data driver 2 includes a shift register array 4 for supplying a sequential sampling signal and a latch for sequentially latching and simultaneously outputting video data R, G, and B in response to the sampling signal. Array 6, digital-to-analog conversion (hereinafter referred to as "DAC") array 8 for converting video data from latch array 6 into an analog data signal, and data signal from DAC array 8 And a buffer array 10 for buffering and outputting the buffer. The data driver 2 having such a configuration drives n data lines DL1 to DLn.

The plurality of shift registers of the shift register array 4 sequentially shift the input source start pulse SSP according to the source sampling clock signal SSC and output the sampling signal.

A plurality of latches configured in the latch array 6 are sequentially latched by sampling input pixel data by a predetermined unit in response to a sampling signal from the shift register array 4 and simultaneously in response to a source output enable signal SOE. Output

A plurality of DACs configured in the DAC array 8 converts the data from the latch array 6 to analog data using positive and negative gamma voltages from a gamma voltage generator (not shown). The signal is converted and output. In particular, the DAC array 8 converts the odd-numbered and even-numbered data signals to have opposite polarities for dot inversion driving in response to the input polarity control signal POL, and converts the data every one horizontal period (1H). Causes the polarity of the signal to be reversed.

The buffer array 10 buffers the data signals output from the DAC array 8 and supplies them to the data lines DL1 to DLn.

The liquid crystal display device driven by the above method is divided into a normally white mode and a normally black mode according to the direction in which the liquid crystal is injected into the liquid crystal panel. In this case, the liquid crystal display is driven by the gamma voltage Vγ shown in FIG. 2A, and the liquid crystal display is driven by the gamma voltage Vγ shown in FIG. 2B. That is, the liquid crystal display requires different gamma voltages Vγ depending on the driving method thereof. However, since the driving device of the conventional liquid crystal display device drives only one of the normally white mode and the normally black mode, there is a problem of separately manufacturing the data driver 2 according to each mode.

Accordingly, it is an object of the present invention to provide a driving apparatus for a liquid crystal display device and a driving method thereof capable of selectively switching a normally white mode and a normally black mode according to a driving method of the liquid crystal display device.

In order to achieve the above object, the driving apparatus of the liquid crystal display according to the present invention includes a gamma voltage generator for generating a plurality of gamma voltages having different voltages; A digital-to-analog converter array supplied with the plurality of gamma voltages and selecting the gamma voltage corresponding to digital input data; A mode selection unit for generating a mode selection signal; And a gamma voltage converter in which the gamma voltages are aligned in one of a forward direction and a reverse direction and supplied to the input terminals in response to the mode selection signal.

The mode selection signal includes a first mode selection signal for driving the liquid crystal display in a normally white mode, and a second mode selection signal for driving the liquid crystal display in a normally black mode. .

The gamma voltage converter supplies a high potential gamma voltage to a first input terminal in response to the first mode selection signal and a low potential gamma voltage to a second input terminal, and in response to the second mode selection signal. The low potential gamma voltage is supplied to one input terminal and the high potential gamma voltage is supplied to the second input terminal.

The gamma voltage converter is characterized by consisting of a plurality of multiplexers.

A liquid crystal panel including a plurality of liquid crystal cells provided at intersections of gate lines and data lines, a gate driver for supplying a scan signal to the gate lines, and a data driver for supplying the gamma voltage to the data lines. And a timing controller for controlling the gate driver and the data driver.

The data driver includes a shift register array for supplying a sequential sampling signal, a latch array for latching and outputting video data in response to the sampling signal, and a buffer array for buffering data signals from the digital-analog converter array. Characterized in that.

A method of driving a liquid crystal display according to an exemplary embodiment of the present invention includes generating a plurality of gamma voltages having different voltages; Selecting the gamma voltage supplied with a plurality of gamma voltages through a plurality of input terminals and corresponding to digital input data; Generating a mode selection signal; And aligning the gamma voltages in one of a forward direction and a reverse direction to the input terminals in response to the mode selection signal.

The generating of the mode selection signal may include generating a first mode selection signal for driving the liquid crystal display in a normally white mode, and selecting a second mode for driving the liquid crystal display in a normally black mode. Generating a signal.

Supplying the gamma voltage to the input terminals comprises supplying a high potential gamma voltage to a first input terminal and a low potential gamma voltage to a second input terminal in response to the first mode selection signal; And supplying the low potential gamma voltage to the first input terminal and the high potential gamma voltage to the second input terminal in response to a second mode selection signal.

The method may further include supplying a scan signal to gate lines of the liquid crystal panel, and supplying the gamma voltage to the data lines of the liquid crystal panel.

Other objects and advantages of the present invention in addition to the above object will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 3 to 5.

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

Referring to FIG. 3, a driving apparatus of a liquid crystal display according to an exemplary embodiment of the present invention includes a digital video card 24 for converting digital video data, a liquid crystal panel 20 in which liquid crystal cells are arranged in a matrix form, A data driver 22 for supplying a data signal to the data lines DL of the liquid crystal panel 20, a gate driver 30 for sequentially driving the gate lines GL of the liquid crystal panel 20, and Of the timing controller 26 for controlling the data driver 22 and the gate driver 30, the gamma voltage generator 28 for supplying the gamma voltage Vγ to the data driver 22, and the liquid crystal display device. And a mode selector 32 for generating a mode selection signal (MSS) according to the driving method.

Liquid crystal is injected between the two glass substrates, and the liquid crystal panel 20 is formed such that the gate lines GL and the data lines DL are orthogonal to each other on the lower glass substrate. A TFT for selectively supplying an image input from the data lines DL to the liquid crystal cell Clc is formed at the intersection of the gate lines GL and the data lines DL. For this purpose, the TFT has a gate terminal connected to the gate line GL, and a source terminal connected to the data line DL. The drain terminal of the TFT is connected to the pixel electrode of the liquid crystal cell Clc.

The digital video card 24 converts an analog input image data signal into a digital image data signal and detects a synchronization signal included in the image data signal. In order to transmit data and control signals from the digital video card 24, a low voltage differential signal (LVDS) interface and a TTL interface are used. In addition, these interface functions are collected and used together with the timing controller 26 in a single chip. The LVDS compresses several data in one line and is input to the timing controller 26.

The timing controller 26 supplies the data signals of red (R), green (G) and blue (B) from the digital video card 24 to the data driver 22. In addition, the timing controller 26 generates a data control signal (Dclk, etc.) and a gate control signal (GSP, etc.) by using the horizontal / vertical synchronization signals (H, V) input from the digital video card 24 to generate a data driver. Timing control of the 22 and the gate driver 30 is performed. The data control signal is supplied to the data driver 22 and the gate control signal is supplied to the gate driver 30.

The gate driver 30 is configured to generate scan pulses sequentially in response to a gate control signal such as a gate start pulse GSP input from the timing controller 26, and to adjust the voltage of the scan pulses to drive the liquid crystal cell. Level shifter and the like for shifting to the level. The gate high voltage is supplied to the gate line between the syringes (1H), and the gate low voltage is applied during the remaining period. In response to the scan pulse input from the gate driver 30, video data on the data line DL is supplied to the pixel electrode of the liquid crystal cell Clc by the TFT.

The data driver 22 receives a data control signal such as dot clock Dclk together with data signals of red (R), green (G), and blue (B) from the timing controller 26. The data driver 22 latches the red (R), green (G), and blue (B) digital video data in synchronization with a data control signal such as a dot clock (Dclk), and then latches the latched data in the mode selection unit. Correction is made in accordance with the gamma voltage Vγ selected by the mode selection signal MSS from (32). The data driver 22 converts the digital video data into an analog pixel voltage signal by the gamma voltage Vγ selected by the mode selection signal MSS, and supplies the digital video data to the data line DL one by one.

The gamma voltage generator 28 generates a gamma voltage Vγ corresponding to the gray scale value of the data in consideration of the electrical and optical characteristics of the liquid crystal panel. The gamma voltage Vγ is a voltage divided by the gamma voltage generator 28 corresponding to the gradation level. Therefore, the gamma voltage Vγ generated from the gamma voltage generator 28 is set to have a different voltage size corresponding to the gray level value selected in the range that can be expressed.

The mode selector 32 generates a mode selection signal MSS according to the driving method of the liquid crystal display when the gamma voltage Vγ generated from the gamma voltage generator 28 is supplied to the data driver 22. . In other words, if the liquid crystal display is driven in the normally white mode when the gamma voltage Vγ shown in FIG. 2A is generated from the gamma voltage generator 28, the mode selector 32 selects a mode of high (1). The signal MSS is generated, and when the liquid crystal display is driven in the normally black mode, the mode selection signal of the low (0) mode is supplied so that the gamma voltage Vγ illustrated in FIG. 2A can be supplied to the data driver 22. MSS). In addition, if the liquid crystal display is driven in the normally white mode when the gamma voltage Vγ shown in FIG. 2B is generated from the gamma voltage generator 28, the mode selector 32 may generate the gamma voltage (see FIG. 2A). Vγ) generates a mode selection signal MSS of low (0) to be supplied to the data driver 22, and the mode selection signal MSS of high 1 when the liquid crystal display is driven in a normally black mode. ) Will occur.

FIG. 4 is a block diagram showing a detailed configuration of the data driver shown in FIG.

Referring to FIG. 4, the data driver 22 includes a shift register array 34 that supplies a sequential sampling signal, and a latch array 36 that latches and outputs video data R, G, and B in response to the sampling signal. ), A gamma voltage converter 42 for converting the gamma voltage Vγ supplied from the gamma voltage generator 28, and a DAC array 38 for converting video data from the latch array 36 into an analog data signal. And a buffer array 40 for buffering and outputting data signals from the DAC array 38.

The plurality of shift registers of the shift register array 34 sequentially shift the input source start pulse SSP according to the source sampling clock signal SSC and output the sampling signal.

A plurality of latches configured in the latch array 36 are sequentially latched by sampling input pixel data by a predetermined unit in response to a sampling signal from the shift register array 34 and simultaneously in response to a source output enable signal SOE. Output

The gamma voltage converter 42 is composed of a plurality of multiplexers (hereinafter referred to as "MUXs") as shown in FIG. 5 to form a positive (+) and a negative (-) signal from the gamma voltage generator 28. The DAC array 38 converts the gamma voltages Vγ into positive (+) and negative (-) gamma voltages (Vγ) corresponding to the normally white mode or the normally black mode according to the mode conversion signal MSS. Will be supplied to In other words, when the mode selection signal MSS is high (1), the gamma voltage converter 42 DACs the positive (+) and negative (-) gamma voltages (Vγ) supplied from the gamma voltage generator 28. It is supplied to the array 38 as it is. However, when the mode selection signal MSS is low (0), the gamma voltage converter 42 converts the positive (+) and negative (-) gamma voltages (Vγ) supplied from the gamma voltage generator 28. It is supplied to the DAC array 38. That is, when the liquid crystal display is driven in the normally black mode, when the positive (+) and negative (-) gamma voltages (Vγ) of the normally white mode shown in FIG. 2A are supplied to the gamma voltage converter 42. The gamma voltage converter 42 converts the positive (+) and negative (−) gamma voltages (Vγ) of the normally black mode shown in FIG. 2B to supply the DAC array 38. Further, when the liquid crystal display is driven in the normally white mode, when the positive (+) and negative (-) gamma voltages (Vγ) of the normally black mode shown in FIG. 2B are supplied to the gamma voltage converter 42. The gamma voltage converter 42 converts the positive (+) and negative (−) gamma voltages (Vγ) of the normally white mode shown in FIG. 2A and supplies them to the DAC array 38.

In more detail, the gamma voltage converter 42 includes the first to fifth gamma voltages GMA1 of the positive polarity (+) supplied from the gamma voltage generator 28 when the mode selection signal MSS is high (1). To GMA5 are supplied to match the first to fifth gamma voltages GMA1 'to GMA5' which are the positive (+) terminals of the DAC array 38. In addition, the sixth to tenth gamma voltages GMA6 to GMA10 of the negative polarity (−) supplied from the gamma voltage generator 28 are the sixth to tenth gamma which are the negative polarity (−) terminals of the DAC array 38. Supply is made to match the voltage (GMA6 'to GMA10') terminal. That is, when the mode selection signal MSS is high (1), the gamma voltage converter 42 aligns the gamma voltage Vγ supplied from the gamma voltage generator 28 in the forward direction to supply the DAC array 38. do.

However, the gamma voltage converter 42 has the first to fifth gamma voltages GMA1 to GMA5 of positive polarity (+) supplied from the gamma voltage generator 28 when the mode selection signal MSS is low (0). The sixth and tenth gamma voltages GMA6 to GMA10 of the negative polarity (−) are reversed and supplied to the positive and negative terminals of the DAC array 38. In other words, the first gamma voltage GMA1 of the first to fifth gamma voltages GMA1 to GMA5 of the positive polarity (+) supplied from the gamma voltage generator 28 may be connected to the DAC array (DAC) through the fourth MUX 50d. 38 is supplied to the fifth gamma voltage GMA5 'terminal, and the second gamma voltage GMA2 is supplied to the fourth gamma voltage GMA4' terminal of the DAC array 38 through the third MUX 50c. Lose. In addition, the fourth gamma voltage GMA4 is supplied to the second gamma voltage GMA2 'terminal of the DAC array 38 through the second MUX 50b, and the fifth gamma voltage GMA5 is supplied to the first MUX 50a. ) Is supplied to the first gamma voltage GMA1 'terminal of the DAC array 38. At this time, the third gamma voltage GMA3 supplied from the gamma voltage generator 28 is supplied to the third gamma voltage GMA3 'of the DAC array 38. In addition, the sixth gamma voltage GMA6 among the sixth to tenth gamma voltages GMA6 to GMA10 of the negative polarity (−) supplied from the gamma voltage generator 28 is the DAC array 38 through the eighth MUX 50h. 7th gamma voltage GMA7 is supplied to the ninth gamma voltage GMA9 'terminal of the DAC array 38 through the seventh MUX 50g. . In addition, the ninth gamma voltage GMA9 is supplied to the seventh gamma voltage GMA7 'terminal of the DAC array 38 through the sixth MUX 50f, and the tenth gamma voltage GMA10 is applied to the fifth MUX 50e. ) Is supplied to the sixth gamma voltage (GMA6 ') terminal of the DAC array 38. At this time, the eighth gamma voltage GMA8 supplied from the gamma voltage generator 28 is supplied to the eighth gamma voltage GMA8 'of the DAC array 38. As described above, the gamma voltage converter 42 applies the positive and negative gamma voltages Vγ supplied from the gamma voltage generator 28 when the mode selection signal MSS is low (0). It is converted in the reverse direction and supplied to the positive (+) and negative (-) gamma voltage (Vγ) terminals of the DAC array 38. For this reason, when the gamma voltage Vγ shown in FIG. 2A is supplied to the gamma voltage converter 42 when the liquid crystal display is driven in the normally black mode, the gamma voltage converter 42 may generate the gamma voltage (see FIG. 2B). Vγ) to be supplied to the DAC array 38. In addition, if the gamma voltage Vγ shown in FIG. 2B is supplied to the gamma voltage converter 42 when the liquid crystal display is driven in a normally white mode, the gamma voltage converter 42 may be gamma voltage Vγ shown in FIG. 2A. ) Is supplied to the DAC array 38.

A plurality of DACs configured in the DAC array 38 utilizes the positive and negative gamma voltages converted by the gamma voltage converter 42 to convert data from the latch array 36 into an analog data signal. The output will be converted to. In particular, the DAC array 38 converts the odd-numbered and even-numbered data signals to have opposite polarities for driving the liquid crystal panel in response to the input polarity control signal POL, and converts the data every one horizontal period (1H). Causes the polarity of the signal to be reversed.

The buffer array 40 buffers the data signals output from the DAC array 38 and supplies them to the data lines DL1 to DLn.

As described above, the driving apparatus and the driving method thereof according to the present invention convert the gamma voltage supplied from the gamma voltage generator to the liquid crystal display by using the mode selection signal, according to the driving method of the liquid crystal display. It is possible to selectively switch between the normally white mode and the normally black mode.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a detailed configuration of a data driver according to a conventional liquid crystal display device.

2A is a diagram illustrating a gamma voltage of a normally white mode.

2B is a diagram illustrating a gamma voltage of a normally black mode.

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

4 is a diagram showing a detailed configuration diagram of the data driver shown in FIG. 3;

FIG. 5 is a diagram illustrating a gamma voltage converter shown in FIG. 4. FIG.

<Description of main parts of drawing>

2, 22: data driver 4, 34: shift register array

6, 36: latch array 8, 38: DAC array

10, 40: buffer array 20: liquid crystal panel

24: digital video card 26: timing controller

28: gamma voltage generator 30: gate driver

32: mode selector 42: gamma voltage converter

50a to 50h: multiplexer

Claims (10)

A gamma voltage generator for generating a plurality of gamma voltages having different voltages; A digital-to-analog converter array supplied with the plurality of gamma voltages and selecting the gamma voltage corresponding to digital input data; A mode selection unit for generating a mode selection signal; And a gamma voltage converter for aligning the gamma voltages in one of a forward direction and a reverse direction and supplying the gamma voltages to the input terminals in response to the mode selection signal. The method of claim 1, The mode selection signal, A first mode selection signal for driving the liquid crystal display in a normally white mode; And a second mode selection signal for driving the liquid crystal display in a normally black mode. The method of claim 2, The gamma voltage converter, Supplying a high potential gamma voltage to a first input terminal and a low potential gamma voltage to a second input terminal in response to the first mode selection signal, And a low potential gamma voltage to the first input terminal and a high potential gamma voltage to the second input terminal in response to the second mode selection signal. The method of claim 3, wherein And the gamma voltage converter is configured of a plurality of multiplexers. The method of claim 1, A liquid crystal panel including a plurality of liquid crystal cells provided at intersections of gate lines and data lines; A gate driver for supplying scan signals to the gate lines; A data driver for supplying the gamma voltage to the data lines; And a timing controller for controlling the gate driver and the data driver. The method of claim 5, The data driver, A shift register array for supplying a sequential sampling signal; A latch array for latching and outputting video data in response to the sampling signal; And a buffer array for buffering data signals from the digital-to-analog converter array. Generating a plurality of gamma voltages having different voltages; Selecting the gamma voltage supplied with a plurality of gamma voltages through a plurality of input terminals and corresponding to digital input data; Generating a mode selection signal; And aligning the gamma voltages in one of a forward direction and a reverse direction to the input terminals in response to the mode selection signal. The method of claim 7, wherein The generating of the mode selection signal may include: Generating a first mode selection signal for driving the liquid crystal display in a normally white mode; And generating a second mode selection signal for driving the liquid crystal display in a normally black mode. The method of claim 7, wherein The step of supplying the gamma voltage to the input terminal, Supplying a high potential gamma voltage to a first input terminal and a low potential gamma voltage to a second input terminal in response to the first mode selection signal; And supplying the low potential gamma voltage to the first input terminal and the high potential gamma voltage to the second input terminal in response to the second mode selection signal. . The method of claim 7, wherein Supplying a scan signal to gate lines of the liquid crystal panel; And supplying the gamma voltage to data lines of the liquid crystal panel.