KR101211239B1 - Liquid crystal display device and driving method of the same - Google Patents

Abstract

The present invention can prevent the display quality deterioration due to the liquid crystal response deviation between the liquid crystal in each divided driving region of the scanning backlight when the high-speed driving method and the scanning backlight driving to turn on the backlight sequentially. A liquid crystal display device and a driving method thereof are provided.

According to an aspect of the present invention, there is provided a liquid crystal display including a backlight for sequentially supplying a plurality of lamp groups to supply light to a liquid crystal display panel, the result of comparing a previous frame and current frame data and at least corresponding to each of the lamp groups. And a modulator for modulating current frame data according to a driving order of two or more scan line groups, wherein the modulator includes lookup tables in which modulation data is set differently according to the at least two scan line groups.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY DEVICE AND DRIVING METHOD OF THE SAME}

1 is a waveform diagram showing a change in luminance in accordance with data in a conventional liquid crystal display device.

Fig. 2 is a waveform diagram showing an example of a luminance change caused by data modulation in the high speed driving method.

3 shows an example of a high speed drive device.

4 is a diagram illustrating a response speed delay between liquid crystals in a predetermined sphere during sequential lighting of conventional lamps.

5 is a view showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 6 is a perspective view illustrating the backlight of FIG. 5; FIG.

7 is a diagram illustrating that lamps of the backlight of FIG. 6 are sequentially turned on;

FIG. 8 is a circuit block diagram illustrating in detail the image quality improvement unit of FIG. 5. FIG.

9 is a diagram illustrating that liquid crystal response speed delay is compensated for by providing the image quality improving unit of FIG. 8.

      Description of the Related Art

32: data bus 33a, 33b, 161,162: frame memory

34,164a, 164b, 164c: Lookup Table 130: Timing Controller

50,150: backlight 154: lamp group

152: Lamp 140: System

142: picture quality improvement unit 132: power supply unit

126: gate driver 124: data driver

122; LCD panel 136: Inverter

168 switch unit 172 control 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 and method for a liquid crystal display device which simultaneously performs a high speed driving method and a scanning backlight driving method.

The liquid crystal display adjusts the light transmittance of liquid crystal cells according to a video signal to display an image.

Among the liquid crystal display devices, an active matrix type liquid crystal display device in which switching elements are formed for each liquid crystal cell is advantageous in implementing a moving picture because active control of the switching elements is possible. As a switching element used in an active matrix type liquid crystal display device, a thin film transistor (hereinafter referred to as TFT) is mainly used.

As can be seen in Equations 1 and 2, the liquid crystal display has a disadvantage in that the response speed is slow due to the inherent viscosity and elasticity of the liquid crystal.

(gamma)는 액정분자의 회전점도(rotational viscosity)를 각각 의미한다. Where τr is the rising time when voltage is applied to the liquid crystal, Va is the applied voltage, VF is the Freederick Transition Voltage at which the liquid crystal molecules start the tilt motion, and d is the liquid crystal. The cell gap of the cell,

(gamma) means the rotational viscosity of the liquid crystal molecule, respectively.

Here, τf denotes a falling time at which the liquid crystal is restored to its original value due to the elastic restoring force after the voltage applied to the liquid crystal is turned off, and K denotes the elastic modulus inherent to the liquid crystal.

Although the liquid crystal response speed of TN mode (Twisted Nematic mode), which has been the most commonly used liquid crystal display device, can vary depending on the physical properties of the liquid crystal material and the cell gap, the rising time is 20-80ms and the polling time is generally 20-30 ms. The response speed of the liquid crystal is longer than one frame period (NTSC: 16.67ms). For this reason, as shown in FIG. 1, since the voltage charged in the liquid crystal cell reaches the next voltage, a motion blur phenomenon occurs in which the screen is blurred in the video.

Referring to FIG. 1, in the conventional LCD, when the data VD changes from one level to another level due to a slow response speed, the corresponding display luminance BL does not reach the desired luminance, and thus the desired color and luminance. Will not be represented. As a result, the liquid crystal display exhibits a motion blur phenomenon in a moving image, and the image quality is deteriorated due to a decrease in contrast ratio.

In order to solve the slow response speed of the liquid crystal display, U.S. Patent No. 5,495,265 and PCT International Publication No. WO 99/05567 use a lookup table to modulate the data depending on whether or not the data is changed (hereinafter, 'high speed driving'). Has been proposed. This high-speed driving method modulates data by the same principle as in Fig.

을 크게 하게 된다. 따라서, 고속 구동방법을 이용하는 액정표시장 치는 액정의 늦은 응답속도를 데이터값의 변조로 보상하여 동영상에서 모션 블러 현상을 완화시킨다. Referring to FIG. 2, the high speed driving method modulates the input data VD into preset modulation data MVD and applies the modulation data MVD to the liquid crystal cell to obtain a desired luminance MBL. This high-speed driving method uses Equation 1 based on whether or not the data changes so as to obtain a desired luminance corresponding to the luminance value of the input data within one frame period.

. Therefore, the liquid crystal display using the high speed driving method compensates for the late response speed of the liquid crystal by modulating the data value to mitigate the motion blur phenomenon in the video.

In other words, the high speed driving method compares data between the previous frame and the current frame and modulates the data of the current frame with preset modulation data if there is a change between the data. The high speed drive device in which the high speed drive method is implemented may be implemented as shown in FIG. 3.

Referring to FIG. 3, the high speed drive device includes first and second frame memories 33a for storing data from the data bus 32 and a lookup table 34 for modulating the data.

The first and second frame memories 33a and 43b alternately store data in units of frames in accordance with the pixel clock, alternately output the stored data, and output the previous frame data, that is, the n-1 th frame data, to the lookup table 34. (Fn-1) is supplied.

The lookup table 34 compares and compares the n-th frame data Fn from the data input bus 32 with the n-th frame data Fn from the first and second frame memories 33a and 43b. The modulation data MRGB corresponding to the result is selected. Modulated data MRGB is stored in read-only memory (ROM) in lookup table 34.

Briefly referring to the operation of the high speed driving device, as shown by the solid line during the nth frame period, the nth frame data Fn is stored in the first frame memory 33a and the lookup table 34 at the same pixel clock. Is supplied. At the same time, the second frame memory 33b supplies the n−1 th frame data Fn−1 to the lookup table 34 during the n th frame period.

In contrast, during the n + 1 th frame period, the current n + 1 th frame data Fn + 1 is stored in the second frame memory 33b at the same time as the dotted pixel clock, and the lookup table 34 Supplied to. At the same time, the first frame memory 33b supplies the nth frame data Fn to the lookup table 34 during the n + 1th frame period.

Through such a series of processes, the modulated data MVD is applied to the liquid crystal cell to obtain a desired luminance MBL.

4 is a diagram illustrating a liquid crystal response when the high speed driving device of FIG. 3 is applied to a scanning backlight driving method for sequentially lighting a backlight.

In the scanning backlight driving method of FIG. 4, a plurality of lamps 52 are provided with a backlight 50 for supplying light to the liquid crystal display panel. And each lamp 52 is sequentially lit.

A plurality of lamps 52 are controlled by an inverter (not shown) to directly supply light to the front surface of the liquid crystal display panel.

The inverter supplies a driving signal (eg, PWM) to the lamps 52 included in the backlight 50 to control the lamps 52 on and off. That is, the motion blur phenomenon can be minimized by controlling the on / off of the lamp 52 to have similar characteristics to the cathode ray tube (CRT) having no hold characteristic.

The liquid crystal display device employing both the conventional high speed driving method and the scanning backlight driving is driven by the high speed driving with the same response speed as the entire liquid crystal display panel, so that the driving of the backlight 50 does not drive the lamp for each scan line. As a result, several lamps 52 cover several dozen scan lines.

In FIG. 4, for example, the number of scan lines is 768 lines, and eight lamp groups 54 show scanning driving. Here, each lamp group 54 includes two direct type lamps (for example, CCFLs). Accordingly, in FIG. 4, two lamps 52 are controlled by one inverter and 96 scan lines are in charge of one lamp group 54 during one frame (16.7 ms). In addition, in Fig. 4, each lamp 52 shows a scanning drive by a 50% duty ratio.

In this case, when the backlight 50 is driven by scanning by dividing the liquid crystal display panel into eight regions, each lamp group 54 which is responsible for a total of 96 scan lines is turned on at the same time, but each lamp group is The response speeds of the liquid crystals corresponding to 96 scan lines at 54 are about 2 kHz. That is, the response speed of the liquid crystal corresponding to the 96 th scan line in each lamp group 96 is delayed by about 2 kHz compared to the response speed of the liquid crystal corresponding to the first scan line. Here, the 2 ㎳ delayed liquid crystal response results in an intermediate gray in which the liquid crystal reaction occurs so that the motion blur removal is not sufficiently removed, which still degrades the display quality.

Accordingly, an object of the present invention is to prevent the display quality deterioration due to the liquid crystal response deviation between the liquid crystals in each divided region of the scanning backlight when performing the high speed driving method and the scanning backlight driving to sequentially turn on the backlight. The present invention provides a driving device and method for a liquid crystal display device.

In order to achieve the above object, the present invention is a liquid crystal display device having a backlight for supplying light to the liquid crystal display panel by sequentially lighting a plurality of lamp groups, the result of comparing the previous frame and the current frame data and each of the above A modulator configured to modulate current frame data according to a driving order of at least two scanline groups corresponding to the lamp groups, wherein the modulator includes lookup tables in which modulation data is set differently according to the at least two scanline groups. Characterized in that.

The modulator comprises first and second memories alternately storing the previous frame data and the input data and outputting the stored previous frame data; And a switch unit configured to supply current frame data and previous frame data from the first and second memories to lookup tables corresponding to each of the scan line groups.

The magnitude relationship of the modulation data set in each of the lookup tables may be increased or decreased in proportion to the driving order of the scan line groups.

The switch unit includes switches corresponding to each of the lookup tables, and each of the switches supplies current and previous data corresponding to the scan line group to the lookup table.

Each of the switches is controlled by a control signal for counting a horizontal synchronization signal for synchronizing a scan signal supplied to a scan line with a data signal supplied to a data line of a liquid crystal display panel.

The modulator includes backlight control means for generating a brightness control signal for adjusting the lighting time of the plurality of lamp groups.

A data driving circuit unit converting the modulation data from the modulation unit into analog data and supplying the analog data to a data line of the liquid crystal display panel; A scan driving circuit unit for supplying a scan signal synchronized with the modulated data to the scan line; And a timing controller for controlling the data driver circuit unit and the scan driver circuit unit.

The present invention provides a method of driving a liquid crystal display device having a backlight for sequentially supplying a plurality of lamp groups to supply light to the liquid crystal display panel, wherein the first and second memories are used to display previous frame data and current frame data. Alternately storing and outputting the stored previous frame data; Modulating the current frame data according to a comparison result of the current frame data with previous frame data output from the first and second memories and a driving order of at least two scan line groups corresponding to the respective lamp groups. And modulating the current frame data comprises setting modulated data differently according to the at least two scanline groups.

And supplying the current frame data and the previous frame data output from the first and second memories to lookup tables having different modulation data by using switches corresponding to each of the scan line groups. It is done.

Each of the switches may supply current and previous data corresponding to the scan line group to a lookup table in which modulation data is set differently according to the scan line group.

The magnitude relationship of the modulation data set in each of the lookup tables may be increased or decreased in proportion to the driving order of the scan line groups.

Each of the switches may be controlled by a control signal for counting a horizontal synchronization signal for synchronizing a scan signal supplied to a scan line with a data signal supplied to a data line of a liquid crystal display panel.

And driving the liquid crystal display panel by using modulation data set differently according to the scan line group.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 to 9.

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

Referring to FIG. 5, in the driving apparatus of the liquid crystal display according to the exemplary embodiment of the present invention, m × n liquid crystal cells Clc are arranged in a matrix type, m data lines D1 to Dm and n gates are provided. The data driver for supplying a data signal to the liquid crystal display panel 122 where the lines G1 to Gn intersect and a TFT is formed at the intersection thereof, and the data lines D1 to Dm of the liquid crystal display panel 122. 124, a gate driver 126 for supplying a scan signal to the gate lines G1 to Gn, a gamma voltage supply unit 128 for supplying a gamma voltage to the data driver 124, and a synchronization signal. To generate the voltages supplied to the liquid crystal display panel 122 using the timing controller 130 for controlling the data driver 124 and the gate driver 126 and the voltage supplied from the power supply 132. The / DC converter 134 and the backlight 138 The timing controller controls the inverter 136 and the modulation data Ro, Go, and Bo, which input data (Ri, Gi, Bi) is set to at least two different modulation data according to the driving order of the scan line groups. The image quality improving unit 142 supplied to the 130 is provided.

The system 140 may display the first vertical / horizontal synchronization signals Vsync1 and Hsync1, the first clock signal DCLK1, the first data enable signal DE1, and the input data Ri, Gi, and Bi. 142).

The liquid crystal display panel 122 includes a plurality of liquid crystal cells Clc disposed in a matrix at the intersections of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc supplies a data signal supplied from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Clc. The storage capacitor Cst is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or is formed between the pixel electrode of the liquid crystal cell Clc and the common electrode line to maintain a constant voltage of the liquid crystal cell Clc. Let's do it.

The gamma voltage supply unit 128 supplies a plurality of gamma voltages to the data driver 124.

The data driver 124 converts the modulated digital video data Ro, Go, and Bo into analog analog gamma voltages (data signals) corresponding to the gray scale values in response to the control signal CS from the timing controller 130, The analog gamma voltage is supplied to the data lines D1 to Dm.

The gate driver 126 sequentially supplies scan pulses to the gate lines G1 to Gn in response to the control signal CS from the timing controller 130 to supply a horizontal signal to the liquid crystal display panel 122. Select a line.

The timing controller 130 controls the gate driver 126 and the data driver 124 using the second vertical / horizontal synchronization signals Vsync2 and Hsync2 and the second clock signal DCLK2 input from the image quality improving unit 142. A control signal CS for control is generated. Here, the control signal CS for controlling the gate driver 126 includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like. This includes. The control signal CS for controlling the data driver 124 includes a source start pulse (GSP), a source shift clock (SSC), a source output signal (SOC), and Polarity signal (POL) is included. In addition, the timing controller 130 rearranges the modulation data Ro, Go, and Bo supplied from the image quality improving unit 142 and supplies the rearranged modulation data Ro, Go, and Bo to the data driver 124.

The DC / DC converter 134 boosts or depressurizes a voltage of 3.3V input from the power supply unit 132 to generate a voltage supplied to the liquid crystal display panel 122. The DC / DC converter 134 generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL, a common voltage Vcom, and the like.

As illustrated in FIG. 6, the backlight 150 includes a plurality of direct-type lamps 152 such as CCFLs, which are installed to overlap the liquid crystal display panel 122. The lamps 152 are controlled by the inverter 136 to directly supply light to the front surface of the liquid crystal display panel 122. Accordingly, the liquid crystal display panel 122 has a high luminance and a wide light emitting surface.

The inverter 136 supplies a driving signal (eg, PWM) to each of the lamps included in the backlight 150 to control on / off of the lamps. Herein, the inverter 136 sequentially turns on the lamps 152 as shown in FIG. 7 so that a motion blur phenomenon may be minimized.

6 and 7 show the backlight 50 in the same manner as in the prior art. That is, the number of scan lines is 768 lines, and the eight lamp groups 154 scan the driving. Here, each lamp group 154 includes two direct type lamps (for example, CCFLs). Accordingly, in FIG. 6, two lamps 152 are controlled by one inverter 136 and 96 scan lines are in charge of one lamp group 154 during one frame (16.7 ms). Each of the lamp groups 154a to 154h in the backlight 150 of FIG. 6 has a duty ratio of 50% as shown in FIG. 7 to perform scanning driving.

The inverter 136 adjusts the on time of the lamp groups 154 in response to the brightness control signal Dimming supplied from the image quality improving unit 142. Here, the brightness control signal Dimming may be generated by any technique known in the art as well as a number of methods proposed in the prior application No. 2003-0099246. For example, the image quality improving unit 142 extracts a luminance component on a frame-by-frame basis using input data Ri, Gi, and Bi input from the system 140 and dims the brightness control signal corresponding to the extracted luminance component. ) Is generated and supplied to the inverter 136.

The image quality improving unit 142 compares the input data Ri, Gi, Bi between the previous frame and the current frame, and if there is a change between the data Ri, Gi, Bi, the preset modulation data Ro, Go And modulates the data of the current frame and modulates the input data Ri, Gi, Bi with different sizes according to the driving order of the scan line groups in charge of the respective lamp groups 154. Accordingly, the variation in the response speed between the first scan line and the 96th scan line in each lamp group 154 can be significantly reduced. As a result, the motion blur is sufficiently removed and the display quality is improved.

Hereinafter, the detailed configuration and operation effects of the image quality improving unit 142 in the present invention will be described in detail with reference to FIG. 8.

The image quality improving unit 142 of FIG. 8 includes first and second frame memories 161 and 162 for storing input data Ri, Gi, and Bi, and at least for modulating the input data Ri, Gi, Bi. Switch unit for selectively supplying two or more lookup tables (LUTs) 164a to 164c and input data Ri, Gi, Bi to any one of the predetermined lookup tables 164a to 164c And a controller 172 for generating the second vertical / horizontal synchronization signals Vsync2 and Hsync2, the second clock signal DCLK2, and the second data enable signal DE2.

The controller 172 receives the first vertical / horizontal synchronization signals Vsync1 and Hsync1, the first clock signal DCLK1, and the first data enable signal DE1 input from the system 140. In addition, the controller 68 may apply the second vertical / horizontal synchronization signals Vsync2 and Hsync2, the second clock signal DCLK2, and the second data enable signal DE2 to be synchronized with the modulation data Ro, Go, and Bo. It generates and supplies to the timing controller 130.

The first and second frame memories 161 and 162 alternately store the input data Ri, Gi, and Bi in frame units according to the pixel clock, and alternately output the stored input data Ri, Gi, and Bi to switch units ( 168, the previous frame data, that is, the n-1 th frame data Fn-1.

The switch unit 168 is provided with a number of switches corresponding to each of the lookup tables. For example, when there are three lookup tables, the first to third switches 168a, 168b, and 168c are provided. The first to third switches 168a, 168b, and 168c are controlled by a switch control signal SCS that counts the first horizontal synchronization signal Hsync1.

For example, when the scan line of one lamp group 154 is 96 lines, the first switch 168a is turned on by the first switch control signal SCS1 to the first to 32nd scan lines. Corresponding data is supplied to the lookup table, data corresponding to the 33rd to 64th scan lines are supplied to the lookup table while the second switch 168b is turned on by the second switch control signal SCS2. While the third switch 168c is turned on by the switch control signal SCS3, data corresponding to the 65th to 96th scan lines is supplied to the lookup table. The first to third switches 168a, 168b, and 168c are sequentially turned on during the driving time (1/8 frame period) of the scan lines to which each lamp group 154 is responsible.

At least two or more lookup tables (an example of using three lookup tables is illustrated in FIG. 8), that is, each of the first to third lookup tables 164a to 164c may include the first to third switches 168a and 168b, 168c).

Accordingly, the first lookup table 164a is supplied with input data corresponding to the first to thirty-second scan lines (hereinafter, referred to as "first scan line groups") in each lamp group 154, The second lookup table 164b is supplied with input data corresponding to the 33rd to 63rd scanlines (hereinafter, referred to as "the second scanline group") in each lamp group 154, and the third lookup. The table 164c is supplied with input data corresponding to the 65th through 96th scan lines (hereinafter, referred to as "third scan line group") in each lamp group 154.

The first lookup table 164a includes input data Ri, Gi, Bi and frame memories 161 and 162 synchronized to the first scan line group in the n-th frame data Fn via the first switch 168a. Compares the input data Ri, Gi, and Bi corresponding to the first scan line group with the n-1 th frame data Fn from the N-th frame data (Fn) and first modulation data (Ro, Go, Bo) corresponding to the comparison result. Select.

The second lookup table 164b includes input data Ri, Gi, and Bi corresponding to the second scan line group in the nth frame data Fn via the second switch 168b and the frame memories 161 and 162. Compares the input data Ri, Gi, Bi corresponding to the second scan line group from the n-1 th frame data Fn from the < RTI ID = 0.0 > 1, < / RTI > Select.

The third lookup table 164c includes input data Ri, Gi, and Bi corresponding to the third scan line group from the nth frame data Fn via the first switch 168c and the frame memories 161 and 162. The input data Ri, Gi, Bi corresponding to the third scan line group is compared with the n−1 th frame data Fn, and the third modulation data Ro, Go, Bo is selected corresponding to the comparison result. .

Here, the first to third modulation data (Ro, Go, Bo) is determined in magnitude according to the driving order of the scan line groups.

That is, a response speed delay occurs in the liquid crystal corresponding to the second scan line groups as compared to the liquid crystal corresponding to the first scan line groups, and third scan line groups as compared to the liquid crystal corresponding to the second scan line groups. The response speed delay occurs in the liquid crystal corresponding to.

Accordingly, the degree of compensation for the input data value in the second modulation data corresponding to the second scan line groups is set to be greater than the compensation value in the first modulation data corresponding to the first scan line groups, and the third The compensation degree of the input data value in the third modulation data corresponding to the scan line group is set to be larger than the compensation value in the second modulation data corresponding to the second scan line group.

As a result, as shown in FIG. 9, the liquid crystals corresponding to the second scan line groups B are faster than the liquid crystals corresponding to the first scan line groups A (when LUT1 is applied). When LC response> LUT2 is applied, liquid crystals corresponding to the third scan line groups C are faster than the liquid crystals corresponding to the second scan line groups B. (When LUT2 is applied) LC response> LC response when LUT3 is applied. For example, the target response speed of the liquid crystals corresponding to the first scan line groups A is increased by high-speed driving by the first modulated data from the first lookup table 164a. If it is about 8 kHz, the target response speed of the liquid crystal corresponding to the second scan line groups B is about 7 s by high-speed driving by the second modulated data from the second lookup table 164b, and the third Corresponding to the third scan line groups C by the high speed driving by the third modulated data from the lookup table 164c. Is the target response time of liquid crystal to be approximately 6㎳.

Accordingly, the variation in response speed within the first to 96th scan lines of each lamp group 154 may be compensated for, such as the 2 ㎳ response response of the first and the 96th scan lines. Can be reduced. As a result, the motion blur is sufficiently removed and the display quality is improved. Modulated data (Ro, Go, Bo) is stored in read-only memory (ROM) in the first to third lookup tables (164a, 164b, 164c).

The driving method of the liquid crystal display using the image quality improving unit 142 of the present invention will be briefly described as follows.

During the nth frame period, as shown by the solid line in FIG. 8, the nth frame data Ri, Gi, and Bi are stored in the first frame memory 161 and supplied to the switch unit 168 at the same pixel clock. . At the same time, the second frame memory 162 supplies the n−1 th frame data Ri, Gi, and Bi to the switch unit 168 during the n th frame period.

At this time, the first switch 168a of the switch unit 168 is nth corresponding to the first scan line group A in charge of the lamp group 154 that is turned on by being turned on by the first switch control signal SCS1. The input data Ri, Gi, Bi of the frame and the n−1 th frame input data Ri, Gi, Bi are supplied to the first lookup table 164a.

The second switch 168b of the switch unit 168 of the n-th frame corresponding to the second scan line group B in charge of the lamp group 154 that is turned on by the second switch control signal SCS2 is turned on. The input data Ri, Gi, Bi and the n−1 th frame input data Ri, Gi, Bi are supplied to the second lookup table 164b.

The third switch 168c of the switch unit 168 of the n-th frame corresponding to the second scan line group C which is in charge of the lamp group 154 that is turned on by being turned on by the third switch control signal SCS3. The input data and the n-1 th frame input data are supplied to the third lookup table 164c.

Thereafter, the first lookup table 164a compares the n th and n-1 th input data from the first switch 168a and selects the first modulation data Ro, Go, Bo corresponding to the comparison result. . The second lookup table 164b compares the nth and n−1th input data from the second switch 168b and selects second modulation data Ro, Go, and Bo corresponding to the comparison result. The third lookup table 164c compares the nth and n−1th input data from the third switch 168c and selects third modulation data Ro, Go, and Bo corresponding to the comparison result.

During the n + 1 th frame period, the current n + 1 th frame data Ri, Gi, Bi is stored in the second frame memory 162 at the same time as the dotted pixel clock of FIG. 8. 168 is supplied. At the same time, the first frame memory 161 supplies the n-th frame data Ri, Gi, Bi to the switch unit 168 during the n-th frame period. Thereafter, the driving method of the switch unit 168 and the first to third lookup tables 164a, 164b, and 164c is performed in the same manner as the above-described method.

The first to third modulated data Ro, Go, and Bo modulated through the series of processes are supplied to the data driver 124 via the timing controller 130. Thereafter, the data driver 124 converts the modulation data (Ro, Go, Bo) into analog data and applies it to the liquid crystal cell of the liquid crystal display panel 122. As a result, the variation in response speed between liquid crystals in each lamp group is reduced, thereby improving display quality.

As described above, the driving apparatus and method of the liquid crystal display according to the present invention implements a high-speed driving method and at least corresponding to the comparison result and lamp groups of the previous frame and the current frame data when scanning backlight driving is performed. And a modulator for modulating current frame data according to a driving order of two or more scan line groups. In particular, the modulator may include look-up tables in which modulation data is set differently according to scan line groups, thereby significantly reducing a variation in response speed between scan lines in each lamp group. As a result, the motion blur is sufficiently removed and the display quality is improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the 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.

Claims (13)

A liquid crystal display device comprising a backlight for supplying light to a liquid crystal display panel by sequentially lighting a plurality of lamp groups. A modulator configured to modulate the current frame data according to a comparison result of a previous frame and current frame data and a driving order of at least two scan line groups corresponding to the lamp groups, The modulator Lookup tables in which modulation data is set differently according to the at least two scanline groups; First and second memories alternately storing the previous frame data and the current frame data and outputting the stored previous frame data; And a switch unit which supplies current frame data and previous frame data from the first and second memories to lookup tables corresponding to each of the scan line groups. delete The method of claim 1, The magnitude relationship of the modulation data set in each of the lookup tables is And increasing / decreasing in proportion to the driving order of the scan line groups. The method of claim 1, The switch unit is composed of switches corresponding to each of the lookup tables, Each of the switches And supplying current and previous data corresponding to the scan line group to the lookup table. 5. The method of claim 4, And each of the switches is controlled by a control signal for counting a horizontal synchronization signal for synchronizing a scan signal supplied to a scan line with a data signal supplied to a data line of a liquid crystal display panel. The method of claim 1, The modulator And backlight control means for generating a brightness control signal for adjusting the lighting time of the plurality of lamp groups. The method of claim 1, A data driving circuit unit converting the modulation data from the modulation unit into analog data and supplying the analog data to a data line of the liquid crystal display panel; A scan driving circuit unit for supplying a scan signal synchronized with the modulated data to the scan line; And a timing controller for controlling the data driver circuit unit and the scan driver circuit unit. In the driving method of the liquid crystal display device having a backlight for supplying light to the liquid crystal display panel by sequentially lighting a plurality of lamp groups, Alternately storing previous frame data and current frame data using first and second memories and outputting the stored previous frame data; Modulating the current frame data according to a comparison result of the current frame data with previous frame data output from the first and second memories and a driving order of at least two scan line groups corresponding to the respective lamp groups. Including, Modulating the current frame data Differently setting modulated data according to the at least two scan line groups; And supplying the current frame data and the previous frame data output from the first and second memories to lookup tables having different modulation data by using switches corresponding to each of the scan line groups. A method of driving a liquid crystal display device. delete 9. The method of claim 8, Each of the switches And supplying current and previous data corresponding to the scan line group to a lookup table in which modulation data is set differently according to the scan line group. 9. The method of claim 8, The magnitude relationship of the modulation data set in each of the lookup tables is And increasing / decreasing in proportion to the driving order of the scan line groups. 9. The method of claim 8, Each of the switches is controlled by a control signal that counts a horizontal synchronization signal for synchronizing a scan signal supplied to a scan line with a data signal supplied to a data line of a liquid crystal display panel. . 9. The method of claim 8, And driving the liquid crystal display panel using modulated data set differently according to the scan line group.

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