KR20080084150A - Driving circuit for liquid crystal display device and method for driving the same - Google Patents

Abstract

A driver of an LCD device and a driving method thereof are provided to reduce power consumption of a backlight unit by controlling operation timing of the backlight according to image signals. A driver of an LCD(Liquid Crystal Display) device includes an LCD panel(2), a data driver(4), a gamma voltage supplier(10), a detector, and a timing controller(8). The LCD panel includes pixel regions at regions defined by plural gate and data lines. The data driver drives the data lines. The gamma voltage supplier converts a driving voltage from a power supply unit into different plural gamma voltages and supplies the different gamma voltages to the data driver. The detector detects variation amounts of the driving voltage supplied to the gamma voltage supplier. The timing controller controls a backlight(16) by varying a dimming signal according to the variation amounts of the driving voltage, modulates image data according to the variation amounts and threshold values of the driving voltage, and supplies the modulated image data to the data driver.

Description

Driving device for liquid crystal display and driving method thereof {Driving circuit for liquid crystal display device and method for driving the same}

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

FIG. 2 is a configuration diagram illustrating the timing controller shown in FIG. 1. FIG.

3 is a configuration diagram illustrating an image processor shown in FIG. 2;

4 is a configuration diagram illustrating an offset setting unit illustrated in FIG. 2.

5 is a graph showing a change in the amount of current detected in every horizontal section by the detector shown in FIG.

6 is a graph illustrating a change in dimming value compared to an offset signal according to an embodiment of the present invention.

7 is a block diagram showing a timing controller according to another embodiment of the present invention.

FIG. 8 is a configuration diagram illustrating an image processor illustrated in FIG. 7.

9 is a configuration diagram illustrating an offset setting unit illustrated in FIG. 8.

＊ Description of symbols for main parts of the drawings ＊

8, 28: timing controller 186, 286: detector

81, 281: image processor 82, 282: offset setting unit

85, 285: inverter control unit 187, 387: average unit

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 same, which can improve the display efficiency of an image while reducing power consumption.

Recently, liquid crystal displays, field emission displays, plasma display panels, and light emitting displays are emerging as flat panel displays.

Among flat panel displays, a liquid crystal display displays an image by adjusting the light transmittance of a liquid crystal having dielectric anisotropy using an electric field. To this end, the liquid crystal display includes a liquid crystal panel having pixel regions arranged in a matrix, a driving circuit for driving the liquid crystal panel, and a backlight for supplying light to the liquid crystal panel.

In the liquid crystal panel, a plurality of gate lines and a plurality of data lines are arranged to cross each other, and a pixel region is positioned in an area defined by vertical crossings of the gate lines and the data lines. Pixel electrodes and a common electrode for applying an electric field to each of the pixel regions are formed. Each of the pixel electrodes is connected to a thin film transistor (TFT) which is a switching element. The TFT is turned on by the scan pulse of the gate line, so that the data signal of the data line is charged to the pixel electrode.

The driving circuit uses a gate driver for driving the gate lines, a data driver for driving the data lines, a timing controller for supplying control signals for controlling the gate driver and the data driver, and a driving voltage from an external source. A gamma voltage generator for generating a plurality of gamma voltages and supplying them to the data driver is provided.

Such a liquid crystal display forms an electric field in the liquid crystal layer according to a data signal, and obtains a desired image by adjusting the transmittance of light generated from the backlight and passing through the liquid crystal layer.

However, the conventional liquid crystal display has a problem that the contrast of the displayed image is lowered. Specifically, the LCD cannot extend the contrast of the input image data, and the backlight always supplies constant light to the liquid crystal panel regardless of the image data. That is, since the LCD cannot display an image by clearly extending the contrast between a bright image and a dark image, the contrast of the image is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a driving apparatus and a driving method of the liquid crystal display device which can improve the display efficiency of an image and reduce power consumption.

A driving device of a liquid crystal display according to an exemplary embodiment of the present invention for achieving the above object is a liquid crystal panel having a pixel region in an area defined by a plurality of gates and data lines, and data driving the plurality of data lines. A gamma voltage supply unit for converting a driving voltage from a driver and a power supply unit into a plurality of different gamma voltages and supplying the same to the data driver, a detection unit detecting a change amount of the driving voltage supplied to the gamma voltage driver, and the detected driving voltage And a timing controller for controlling a backlight by varying a dimming control signal according to a change amount of the signal, and modulating the image data according to the detected change amount of the driving voltage and a plurality of threshold values and supplying the data data to the data driver. .

In addition, the driving method of the liquid crystal display device according to an embodiment of the present invention for achieving the above object is to convert the data driver and the driving driving voltage for driving the data lines of the liquid crystal panel into a plurality of different gamma voltage and A driving method of a liquid crystal display device having a gamma voltage supplying unit for supplying a data driver, the method comprising: detecting a change amount of a driving voltage supplied to the gamma voltage supplying unit, according to the detected change amount of the driving voltage and a plurality of threshold values Modulating the image data, and controlling a backlight by varying a dimming control signal according to the detected change amount of the driving voltage.

Hereinafter, a driving apparatus and a driving method thereof of a liquid crystal display according to an exemplary embodiment of the present invention having the above characteristics will be described in detail with reference to the accompanying drawings.

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

The liquid crystal display shown in FIG. 1 includes a liquid crystal panel 2 having a plurality of pixel regions, a data driver 4 for driving the plurality of data lines DL1 to DLm, and a plurality of gate lines GL1 to GLn. Gamma voltage supply unit 10 and gamma converting the driving voltage VD from the gate driver 6 and the power supply unit 12 to the plurality of different gamma voltages VG to be supplied to the data driver 4. Detecting a change amount of the driving voltage VD supplied to the voltage supply unit 10 to vary the dimming control signal Dim according to the detected change amount and to modulate the image data RGB according to a plurality of preset threshold values. Backlight irradiating light to the liquid crystal panel 2 according to the timing controller 8, the inverter 14 generating the lamp driving signal AC according to the variable dimming control signal Dim, and the lamp driving signal AC. (16) is provided.

The liquid crystal panel 2 includes a thin film transistor (TFT) formed in each pixel region defined by a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm, and a liquid crystal capacitor connected to a TFT. (Clc). The liquid crystal capacitor Clc is composed of a pixel electrode connected to a TFT and a common electrode facing each other with the pixel electrode and the liquid crystal interposed therebetween. The TFT supplies the data signals from the respective data lines DL1 to DLm to the pixel electrodes in response to the scan pulses from the respective gate lines GL1 to GLn. The liquid crystal capacitor Clc charges the difference voltage between the data signal supplied to the pixel electrode and the common voltage supplied to the common electrode, and adjusts the light transmittance by varying the arrangement of liquid crystal molecules according to the difference voltage. The storage capacitor Cst is connected to the liquid crystal capacitor Clc in parallel so that the voltage charged in the liquid crystal capacitor Clc is maintained until the next data signal is supplied. The storage capacitor Cst is formed by overlapping the pixel electrode with the previous gate line and the insulating layer interposed therebetween. In contrast, the storage capacitor Cst may be formed by overlapping the pixel electrode with the storage line and the insulating layer interposed therebetween.

The data driver 4 converts the image data Data modulated according to the data control signal DCS from the timing controller 8 into an analog image signal. The analog image data for one horizontal line is supplied to the data lines DL1 to DLm every horizontal period in which scan pulses are supplied to the gate lines GL1 to GLn. That is, the data driver 4 selects a gamma voltage having a predetermined level according to the gray value of the analog video signal and supplies the selected gamma voltage to the data lines DL1 to DLm. In this case, the data driver 4 may invert the polarity of the image signal in the pixel area and in the frame unit according to the polarity control signal of the data control signal DCS.

The gate driver 6 generates a scan pulse, for example, a gate-on voltage in response to the gate control signal GCS from the timing controller 8, and sequentially supplies the gate pulses to the gate lines GL1 to GLn. Accordingly, the gate lines GL1 to GLn of the liquid crystal panel 2 are sequentially driven by the gate-on voltage from the gate driver 6. Here, the gate driver 6 may be formed on the substrate on which the liquid crystal panel 2 is formed at the same time as the manufacturing process of the thin film transistor and connected to each gate line GL1 to GLn.

The power supply unit 12 uses a plurality of driving voltages for driving the liquid crystal display using an input voltage Vin from the outside, for example, a common voltage Vcom, a driving voltage VD, a gate high / low voltage, and the like. Is generated and supplied to the liquid crystal display. In detail, the power supply unit 12 converts the input voltage Vin into a digital driving voltage and supplies it to the gate and data drivers 4 and 6 and the timing controller 8. Herein, the input voltage Vin may be used as the digital driving voltage. The gate low voltage and the gate high voltage are generated using the input voltage Vin and supplied to the gate driver 6. In addition, the common voltage Vcom is generated and supplied to the liquid crystal panel 2, and the analog driving voltage VD is generated and supplied to the data driver 4 and the gamma voltage supply unit 10.

The gamma voltage supply unit 10 generates a plurality of reference gamma voltages or a plurality of different gamma voltages VG using the driving voltage VD supplied from the power supply unit 12. Then, a plurality of different gamma voltages VG are supplied to the data driver 4.

The timing controller 8 arranges the image data RGB from the outside to be suitable for driving the liquid crystal panel 2 and supplies the image data RGB to the data driver 4. The data driver 4 and the gate driver 6 are controlled by generating a gate control signal GCS and a data control signal DCS using the external synchronization signals DCLK, DE, Hsync, and Vsync. .

In addition, the timing controller 8 detects a change amount of the driving voltage VD supplied to the gamma voltage supply unit 10, for example, an amount of current of the driving voltage VD, and drives the driving timing of the backlight 16 according to the detected amount of current. Generate a dimming control signal (Dim) for controlling the. At the same time, the modulated image data Data is generated by modulating the luminance and the gray value of the image data RGB using a preset offset.

The inverter 14 generates a lamp driving signal AC to drive a plurality of lamps included in the backlight 16. In this case, the inverter 14 responds to the converted dimming control signal Dim from the timing controller 8. The lamp driving signal AC is generated. The inverter 14 drives the burst mode to vary the on / off time of the lamp according to the input dimming control signal Dim. In detail, the inverter 14 generates a pulse width modulation signal such that a duty ratio, that is, a high signal ratio in one period, is varied according to the converted dimming control signal Dim. Then, the ramp driving signal AC whose amplitude is modulated to have an on / off time synchronized with the high and low periods of the pulse width modulation signal is generated. Here, the inverter 14 may adjust the brightness of the lamp by varying the on / off time of the lamp or by varying the voltage level of the lamp driving signal AC.

The backlight 16 is composed of a light source for generating light and an optical unit for diffusing and condensing incident light from the light source to improve light efficiency. The light source mainly uses cylindrical lamps such as Cold Cathode Fluorescent Lamp (CCFL) and External Electrode Fluorescent Lamp (EEFL). This lamp is driven by the high voltage AC voltage from the inverter 14, that is, the lamp drive signal AC to generate light.

FIG. 2 is a configuration diagram illustrating the timing controller shown in FIG. 1.

The timing controller 8 illustrated in FIG. 2 detects an amount of current of the driving voltage VD supplied to the image processing unit 81 and the gamma voltage supply unit 10 that modulates the luminance or gray level of the input image data RGB. And an offset setting unit 82 for setting an offset signal OS according to the detected amount of current, a gate control signal generator 83 for driving the gate driver 6, and data control for driving the data driver 4. And an inverter controller 85 that varies the dimming control signal Dim according to the signal generator 84 and the offset signal OS.

The gate control signal generator 83 drives the liquid crystal panel 2 using at least one of an external dot clock DCLK, a data enable signal DE, and vertical and horizontal synchronization signals Vsync and Hsync. The gate control signal GCS is generated. The gate control signal GCS includes a gate start pulse GSP, a gate shift clock GSC, and a gate output enable GOE for controlling the driving timing of the gate driver 6.

The data control signal generator 84 uses an at least one of an external dot clock DCLK, a data enable signal DE, and vertical and horizontal synchronization signals Vsync and Hsync to display an analog image on the liquid crystal panel 2. A data control signal DCS for supplying a signal is generated. In this case, the data control signal DCS may include a source output enable SOE, a source shift clock SSC, a source start pulse SSP, and a polarity control signal POL for controlling the driving timing of the data driver 4. It includes. Here, the polarity control signal POL may be inverted in the pixel area and the frame unit.

As illustrated in FIG. 3, the image processor 81 may generate a first selection signal CS1 by comparing the gray level of the input image data RGB with a preset threshold Offset ( 181, a first selector 182 and a first selector 182 for outputting the image data RGB input according to the first select signal CS1 to the image modulator 183 or the data driver 4. And an image modulator 183 for modulating and outputting a gray value or a luminance value of the image data RGB input from the image data RGB.

The first comparator 181 compares a threshold value preset by the user with a gray value of the image data RGB input. In this case, when the gray value of the image data RGB is larger than the offset value, the first comparator 181 outputs the first selection signal CS1 having a high level, and the gray value of the image data RGB is increased. If it is smaller than the threshold Offset, the first select signal CS1 having a low level is output. For example, when the threshold value is set to '200' and the gray level value of the input image data RGB is '220', the first selection signal CS1 having a high level is output. When the gray level value of the input image data RGB is '100', the first selection signal CS1 having a low level is output. The first comparator 181 may include a luminance detector, a luminance converter, and the like to compare the luminance value of the image data RGB with a threshold value. However, in the present invention, only the case where the gray value of the image data RGB is compared with the threshold value will be described.

The first selector 182 outputs the image data RGB input according to the first select signal CS1 from the first comparator 181 to the image modulator 183 or the data driver 4. In other words, when the first selection signal CS1 is input at a high level, the first selection signal CS1 is output to the image data RGB image modulator 183. When the first selection signal CS1 is input at a low level, the first selection signal CS1 is supplied to the image data RGB data driver 4.

When the image data RGB is input from the first selector 182, the image modulator 183 increases the gray level of the input image data RGB and supplies the same to the data driver 4. In other words, the image modulator 183 modulates the gray value of the image data RGB by adding a preset value to the input gray value of the image data RGB. For example, when the preset value is '5', if the gray value of the image data RGB is input as '220', the gray value is modulated to '225', and when the gray value is input as '232', '237' Modulate 'and supply it to the data driver 4. If the gray scale value of the image data RGB is input to '250' or more, the gray scale value is set to '255' so as not to saturate and is supplied to the data driver 4.

As shown in FIG. 4, the offset setting unit 82 detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10 and generates a detection signal DI corresponding thereto. An average unit 187 for outputting the offset signal OS in accordance with the detection signal DI is provided.

As illustrated in FIG. 5, the detector 186 detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10 in every horizontal period H according to the input horizontal synchronization signal Hsync. . In this case, the amount of current varies depending on the load applied to the gamma voltage supply unit 10. For example, the higher the average gradation value of the image displayed on the liquid crystal panel 2, the greater the load on the gamma voltage supply unit 10, and the lower the average gradation value of the displayed image is applied to the gamma voltage supply unit 10. The load is lowered. Using this, the detector 186 detects the amount of current in each horizontal period unit H and supplies the detection signal DI corresponding thereto to the average unit 187. The detector 186 may be built in the timing controller 8, but may be formed outside the timing controller 8.

The average unit 187 temporarily stores the detection signal DI, which is input in the horizontal period unit H, in a predetermined frame unit, and outputs an offset signal OS corresponding to the stored detection signal DI. . In this case, at least one register or memory may be used to temporarily store the detection signal DI. For example, when the size of the register included in the average unit 187 is set to temporarily store the detection signal DI in units of two frames, the average unit 187 may be configured to store the detection signal DI temporarily stored in units of two frames. The average value is calculated and this average value is output as an offset signal OS. Here, the average unit 187 may calculate the maximum value or the minimum value in addition to the average value of the detection signal DI stored in a predetermined frame unit and output the maximum value or the minimum value as the offset signal OS.

The inverter controller 85 generates a signal in which a dimming value is modulated according to an offset signal OS input in a predetermined frame unit, that is, a dimming control signal Dim. In detail, the inverter controller 85 includes at least one memory to generate a dimming control signal Di corresponding to the input offset signal OS. The modulated dimming control signal Dim is supplied to the inverter 14. That is, referring to FIG. 6, the inverter controller 85 may set the dimming value to 25% to 100% according to the magnitude of the input offset signal OS. In addition, a dimming control signal Dim having a variable duty ratio is generated to correspond to the set dimming value Dimming and is supplied to the inverter 14.

The liquid crystal display according to the exemplary embodiment of the present invention detects the amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10, and varies the dimming control signal Dim according to the detected amount of backlight to display the backlight 16. Drive timing can be controlled. At the same time, the luminance value and the gray value of the image data RGB are modulated according to a preset threshold Offset. Accordingly, the liquid crystal display of the present invention can improve the display efficiency of the image since the image can be displayed by clearly extending the contrast between the bright image and the dark image. In addition, the driving timing of the backlight 16 is controlled according to the image signal Data, thereby reducing power consumption.

7 is a configuration diagram illustrating a timing controller according to another embodiment of the present invention.

The timing controller 28 shown in FIG. 7 detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10 and modulates the luminance or gray level of the image data RGB input according to the detected amount of current. In addition, the image processor 281 for setting the offset signal OS, the gate control signal generator 283 for driving the gate driver 6, and the data control signal generator 284 for driving the data driver 4 are provided. And an inverter control unit 285 for varying and generating the dimming control signal Dim according to the offset signal OS.

The timing controller 28 according to another exemplary embodiment of the present invention has the same configuration and operation method as those of FIG. 2 except for the image processor 281. Therefore, the configuration and operation method of the gate control signal generator 283, the data control signal generator 284, and the inverter controller 285 except for the image processor 281 will be replaced with the description of FIGS. 1 and 2. .

As illustrated in FIG. 8, the image processor 281 compares a gray level of the input image data RGB with a first threshold value Offset1 to generate a first selection signal CS1. A first selector 382 and a first selector for outputting the image data RGB input according to the first select signal CS1 to the second selector 383 or the data driver 4. A second selector 383 and a second to supply an input image from the 382 to the adder 384 or the subtractor 385 in accordance with the second select signal CS2 from the offset setting unit 282. An adder 384 for increasing the luminance or gradation value of the input image supplied from the selector 383, a subtractor 385 for reducing the luminance or gradation value of the input image supplied from the second selector 383; An offset that detects the current amount of the driving voltage VD supplied to the gamma voltage supply unit 10 and outputs an offset signal OS and a second selection signal CS2 according to the detected current amount. And a setting unit (282).

The first comparison unit 381 compares the first threshold value Offset1 preset by the user and the gray value of the image data RGB input. In this case, when the gray value of the image data RGB is greater than the first threshold Offset1, the first comparator 381 outputs the first selection signal CS1 having a high level, and the gray level of the image data RGB. When the value is smaller than the first threshold Offset1, the first select signal CS1 having a low level is output. For example, when the first threshold Offset1 is set to '200' and the grayscale value of the input image data RGB is '220', the first selection signal CS1 having a high level is output. When the gray level value of the input image data RGB is '100', the first selection signal CS1 having a low level is output. The first comparator 381 may include a luminance detector, a luminance converter, and the like to compare the luminance value of the image data RGB with the first threshold Offset1. However, in the present invention, only the case where the gray value of the image data RGB is compared with the first threshold Offset1 will be described.

The first selector 382 outputs the image data RGB input in response to the first select signal CS1 from the first comparator 381 to the second selector 383 or the data driver 4. All. In other words, when the first selection signal CS1 is input at the high level, the first selection signal CS1 is output to the image data RGB second selection unit 383. When the first selection signal CS1 is input at a low level, the first selection signal CS1 is supplied to the image data RGB data driver 4.

The second selector 383 adds or subtracts 384 or 385 the image data RGB from the first selector 382 according to the second select signal CS2 from the offset setting unit 282. Supplies).

The adder 384 increases the gradation value of the image data RGB input from the second selector 383 and supplies it to the data driver 4. In other words, the adder 384 modulates the gray scale value of the image data RGB by adding a preset value to the gray scale value of the input image data RGB. For example, when the preset value is '5', when the gray value of the image data RGB is input as '220', the gray value is modulated to '225', and when the gray value is input as '232', '237' Modulate 'and supply it to the data driver 4. If the gray scale value of the image data RGB is input to '250' or more, the gray scale value is set to '255' so as not to saturate and is supplied to the data driver 4.

The subtractor 385 reduces the gray level of the image data RGB input from the second selector 383 and supplies it to the data driver 4. In other words, the subtractor 385 modulates the gray value of the image data RGB by subtracting a preset value from the input gray value of the image data RGB. For example, when the preset value is '5', when the gray value of the image data RGB is inputted as '155', the gray value is modulated to '150', and when the gray value is inputted as '140', '135' Modulate 'and supply it to the data driver 4.

As illustrated in FIG. 9, the offset setting unit 282 detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10 and generates a detection signal DI corresponding thereto. The second selection signal CS2 is generated using an average unit 387 that outputs an offset signal OS according to the detection signal DI, a preset second threshold Offset2, and an input offset signal OS. And a selection signal generator 389.

As illustrated in FIG. 5, the detector 386 detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10 every horizontal period H according to an input horizontal synchronization signal Hsync. . In this case, the amount of current varies depending on the load applied to the gamma voltage supply unit 10. For example, the higher the average gradation value of the image displayed on the liquid crystal panel 2, the greater the load on the gamma voltage supply unit 10, and the lower the average gradation value of the displayed image is applied to the gamma voltage supply unit 10. The load is lowered. Using this, the detector 386 detects an amount of current every horizontal period unit H, and supplies a detection signal DI corresponding thereto to the average unit 387. The detector 386 may be built in the timing controller 8, but may be formed outside the timing controller 8.

The average unit 387 temporarily stores the detection signal DI input in the horizontal period unit H in a predetermined frame unit, and outputs an offset signal OS corresponding to the stored detection signal DI. . In this case, at least one register or memory may be used to temporarily store the detection signal DI. For example, when the size of the register provided in the averaging section 387 is set to temporarily store the detection signal DI in units of two frames, the averaging section 387 is configured to store the detection signal DI temporarily stored in the unit of two frames. The average value is calculated and the average value is output to the inverter control unit 285 and the selection signal generation unit 389 as an offset signal OS. Here, the average unit 387 may calculate the maximum value or the minimum value in addition to the average value of the detection signal DI stored in a predetermined frame unit and output the maximum value or the minimum value as the offset signal OS.

Referring to FIG. 6, the inverter controller 285 generates a signal in which a dimming value is modulated according to an offset signal OS input in a predetermined frame unit, that is, a dimming control signal Dim.

The selection signal generation unit 389 converts the offset signal OS from the average unit 387 to correspond to the gray scale value and compares it with the second threshold Offset2. When the converted offset signal OS, that is, the offset value is smaller than the second threshold Offset2, the second select signal CS2 having a low level is output to the second selector 383. At this time, when the offset value is larger than the second threshold Offset2, the second selection signal CS2 having the high level is output to the second selector 383. Therefore, it is preferable that the second threshold Offset2 is set higher than the first threshold Offset1.

Accordingly, the second selector 383 of FIG. 8 supplies the image data RGB from the first selector 382 to the adder 384 when the second select signal CS2 is input at a high level. . In addition, when the second selection signal CS2 is input at a low level, the image data RGB from the first selection unit 382 is supplied to the subtraction unit 385.

The liquid crystal display according to another exemplary embodiment of the present invention detects an amount of current of the driving voltage VD supplied to the gamma voltage supply unit 10, and varies the dimming control signal Dim according to the detected amount of backlight to display the backlight 16. Drive timing can be controlled. At the same time, the luminance and gray value of the image data RGB are modulated according to the detected current amount and the first and second threshold values Offset1 and 2 set in advance. Accordingly, the liquid crystal display of the present invention can improve the display efficiency of the image because the image can be displayed by clearly extending the contrast between the bright image and the dark image. In addition, the driving timing of the backlight 16 is controlled according to the image signal Data, thereby reducing power consumption.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is understood that various substitutions, modifications, and changes, such as pixel arrangement and polarity inversion, may be made without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which the invention pertains.

As described above, the liquid crystal display and the driving method thereof according to the embodiment of the present invention have the following effects.

First, the liquid crystal display of the present invention can improve the display efficiency of an image because the image can be displayed by clearly extending the contrast between a bright image and a dark image.

Second, the power consumption of the backlight can be reduced by controlling the driving timing of the backlight according to the image signal.

Third, the manufacturing cost of the liquid crystal display may be reduced by extending the contrast using at least one register.

Claims (24)

A liquid crystal panel having a pixel region in an area defined by a plurality of gates and data lines; A data driver driving the plurality of data lines; A gamma voltage supply unit for converting a driving voltage from a power supply unit into a plurality of different gamma voltages and supplying the same to the data driver; A detector detecting a change amount of the driving voltage supplied to the gamma voltage driver; And And a timing controller configured to control a backlight by varying a dimming control signal according to the detected change of the driving voltage, and to modulate the image data according to the detected change of the driving voltage and a plurality of threshold values and supply the same to the data driver. A drive device for a liquid crystal display device, characterized in that. The method of claim 1, And an inverter configured to generate a lamp driving signal according to a dimming control signal supplied from the timing controller and to control the backlight. The method of claim 2, The detection unit And detecting a current amount of the driving voltage supplied to the gamma voltage supply unit and generating a detection signal corresponding to the detected current amount. The method of claim 3, wherein The timing controller is An image processor which modulates a luminance or a gray value of the image data; An average unit for setting an offset signal according to the detection signal from the detection unit, and And an inverter controller configured to vary and generate the dimming control signal according to the offset signal. The method of claim 4, wherein The image processor A first comparator configured to generate a first selection signal by comparing the gray value or the luminance value of the image data with a preset threshold value; A first selector configured to output image data input according to the first select signal to an image modulator or the data driver; And an image modulator for modulating and outputting a gray value or a luminance value of the image data input from the first selector. The method of claim 5, wherein The image modulator Driving the liquid crystal display device by supplying the gray level value or the luminance value of the image data to the data driver by adding a preset value to the gray level value or the luminance value of the image data inputted from the first selection unit. Device. The method of claim 3, wherein The timing controller is An image processor which modulates a luminance value or a gray scale value of image data input according to a detection signal from the detector, and sets an offset signal; And an inverter controller configured to vary and generate the dimming control signal according to the offset signal. The method of claim 7, wherein The image processor A first comparator configured to generate a first selection signal by comparing the gray level value or the luminance value of the image data with a first threshold value preset; A first selector configured to output image data input according to the first select signal to a second selector or a data driver; A second selector configured to supply the image data input from the first selector to an adder or a subtractor according to a second select signal from an offset setting unit; An adder for increasing the brightness or the gray level of the image data supplied from the second selector, A subtraction unit for reducing the luminance or the gradation value of the image data supplied from the second selection unit, and And an offset setting unit for generating an offset signal and a second selection signal according to the detection signal from the detection unit, and supplying the offset signal and the second selection signal to the inverter control unit and the second selection unit, respectively. The method of claim 8, The offset setting unit An average unit for outputting the offset signal according to the detection signal, and And a selection signal generator for generating a second selection signal by using a second preset threshold value and the offset signal. The method of claim 9, The second threshold is And a value greater than the first threshold. The method of claim 3, wherein The detection unit And a driving device built in the timing controller. The method according to claim 5 or 8, The first comparison unit Outputting a first selection signal having a high level when the gray value or the luminance value of the image data is greater than the threshold value or the first threshold value, and when the gray value of the image data is smaller than the threshold value or the first threshold value And a low level first selection signal. A driving method of a liquid crystal display device having a data driver for driving data lines of a liquid crystal panel and a gamma voltage supply unit for converting the driving driving voltage into a plurality of different gamma voltages and supplying the same to the data driver, Detecting a change amount of a driving voltage supplied to the gamma voltage supplying unit; Modulating the image data according to the detected change amount of the driving voltage and a plurality of threshold values; And And controlling a backlight by varying a dimming control signal according to the detected change in driving voltage. The method of claim 13, Controlling the backlight Generating a ramp driving signal according to the variable dimming control signal; And And controlling the backlight according to the lamp driving signal. The method of claim 14, The detecting amount of change in the driving voltage is Detecting a current amount of the driving voltage, and And generating a detection signal to correspond to the detected current amount of the driving voltage. The method of claim 15, The step of varying the dimming control signal Setting an offset signal according to the detection signal, and And varying and outputting a dimming control signal according to the offset signal. The method of claim 16, Modulating the image data Generating a first selection signal by comparing a gray value or luminance value of the image data with a preset threshold value; and And outputting image data input according to the first selection signal to the data driver or modulating and outputting a gray value or a luminance value of the image data. The method of claim 17, Modulating the gray value or luminance value of the image data And a preset value is added to the gradation value or the luminance value of the image data to increase the gradation value or the luminance value of the image data. The method of claim 15, The image data modulation step Generating a first selection signal by comparing the gray level value or the luminance value of the image data with a first predetermined threshold value; Outputting a second selection signal according to the detection signal and a second threshold value; Outputting image data input according to the first selection signal to the data driver;  Increasing the luminance value or the gray value of the image data according to the second selection signal, and And reducing the luminance value or the gray scale value of the image data according to the second selection signal. The method of claim 19 The dimming control signal variable step And varying and outputting a dimming control signal by modulating a dimming value so as to correspond to the offset signal. The method of claim 19, The second threshold is And a value greater than the first threshold. The method of claim 17 or 19, The first selection signal generating step If the gray value or luminance value of the image data is greater than the threshold value or the first threshold value, a first selection signal having a high level is output, and the gray value value of the image data is smaller than the threshold value or the first threshold value. And outputting a first low level selection signal. The method of claim 15, The detecting signal generating step And detecting a current amount of the driving voltage in every horizontal period and generating a detection signal in every horizontal period so as to correspond to the detected current amount. The method of claim 15, The offset signal setting step And storing any one of the detection signals in at least one frame unit and setting one of an average value, a maximum value, and a minimum value of the stored detection signals as an offset signal.

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