KR20070074792A - Liquid crystal display and driving method thereof - Google Patents

Abstract

An LCD(Liquid Crystal Display) device and a driving method thereof are provided to enhance image quality by displaying gamma compensated images through a data driver. An LCD device includes a liquid crystal panel, gate and data drivers, a region selection signal generator(610), a memory(700), a memory controller(620), and a gamma compensator(630). The liquid crystal panel includes plural pixels. The gate and data drivers supply first and second region signals(AS1,AS2) for selecting column and row region groups, respectively. The region selection signal generator receives the first and second region signals and supplies a region selection signal(ASS). The memory stores gamma compensation data(AGD) for every regions. The memory controller outputs the gamma compensation data from the memory according to the region selection signal. The gamma compensator converts an external image signal(DAT) to an internal image signal(DAT') through gamma compensation based on the gamma compensation data.

Description

Liquid crystal display and driving method thereof

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

2 is an equivalent circuit diagram of one pixel of the liquid crystal display according to the exemplary embodiments of the present invention.

3 is a plan view illustrating a liquid crystal panel assembly of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a plan view illustrating a liquid crystal panel assembly of a liquid crystal display according to another exemplary embodiment of the present invention.

5 is a block diagram illustrating a signal controller and gamma compensation for each region of a liquid crystal display according to exemplary embodiments of the present invention.

(Explanation of symbols for the main parts of the drawing)

10: liquid crystal display device 100: first display panel

150: liquid crystal layer 200: second display panel

300: liquid crystal panel 320: printed circuit board

350: liquid crystal panel assembly 400: gate driver

500: data driver 600: signal controller

610: region selection signal generator 620: memory controller

630: gamma compensation unit 700: memory

800: gray voltage generator

The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly, to a liquid crystal display device and a driving method thereof capable of obtaining excellent image quality.

The liquid crystal display includes first and second display panels on which a pixel electrode and a common electrode are formed, and a liquid crystal layer injected therebetween. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors to receive data voltages one by one in sequence. The common electrode is formed over the entire surface of the second display panel and receives a common voltage. An electric field is formed by the voltage difference applied to the pixel electrode and the common electrode, and the image is displayed by controlling the transmittance of light passing through the liquid crystal layer by adjusting the intensity of the electric field.

For such a liquid crystal display to provide excellent image quality, gamma compensation is required so that the luminance actually measured at all positions of the liquid crystal panel becomes a reference luminance with respect to the gray scale voltage. Meanwhile, high luminance uniformity may be required to obtain excellent image quality. When gamma compensation is constantly performed at all positions of the liquid crystal panel, the luminance is uneven along the area of the liquid crystal panel due to uneven formation of the liquid crystal layer, uneven light provided from the backlight assembly, uneven transmittance of the liquid crystal panel, and the like. Therefore, excellent image quality cannot be obtained. Therefore, it is necessary to increase the luminance uniformity by gamma compensation for each region of the liquid crystal panel.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a liquid crystal display and a driving method thereof capable of obtaining excellent image quality.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an exemplary embodiment of the present invention, a liquid crystal display includes a liquid crystal panel including a plurality of regions, the regions including a plurality of pixels, and a predetermined row region of the matrix. A gate driver providing a first region signal specifying a corresponding row region group, a data driver providing a second region signal specifying a column region group corresponding to a predetermined column region in the matrix, and the first and the first A region selection signal generator for receiving a region signal and providing a region selection signal for selecting one of the plurality of regions, a memory storing gamma compensation data for each region, and the memory according to the region selection signal A gamma compensation signal and an external image signal to output gamma compensation data of the selected area provided from Depending on the data includes gamma compensation unit for converting into the video signal by the gamma compensation.

In addition, the driving method of the liquid crystal display device according to an embodiment of the present invention for achieving the above technical problem, a plurality of areas are divided into a matrix form, the step of providing a liquid crystal panel comprising a plurality of pixels And a first region signal specifying a row region group corresponding to a predetermined row region of the matrix and a second region signal specifying a column region group corresponding to a predetermined column region of the matrix, and receiving one of the plurality of regions. Generating a region selection signal for selecting a region of the region; selecting gamma compensation data corresponding to the selected region in a memory in which gamma compensation data is stored for each region according to the region selection signal; And performing gamma compensation according to the compensation data to convert the image into an internal image signal.

Other specific details of the present invention are included in the detailed description and drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

A liquid crystal display according to exemplary embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

1 is a block diagram of a liquid crystal display according to embodiments of the present invention, and FIG. 2 is an equivalent circuit diagram of one pixel of the liquid crystal display according to embodiments of the present invention.

Referring to FIG. 1, a liquid crystal display according to exemplary embodiments of the present invention may include a liquid crystal panel 300, a gate driver 400 and a data driver 500 connected thereto, a signal controller 600 and a memory 700 that control the liquid crystal panel 300. ) And the gray voltage generator 800.

The liquid crystal panel 300 includes a plurality of display signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels PX connected to the display signal lines G ₁ -G _n , D ₁ -D _m , which are arranged in a matrix form. 2, the liquid crystal panel 300 includes a first display panel 100, a second display panel 200, and a liquid crystal layer 150 interposed therebetween.

The display signal lines G ₁ -G _n and D ₁ -D _m may include a plurality of gate lines G ₁ -G _n transmitting gate signals and a plurality of data lines D ₁ -D _m transmitting data signals. Include. The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and two gate lines are formed for each pixel row. The data lines D ₁ -D _m are formed between two adjacent pixels PX and extend in substantially the column direction and are substantially parallel to each other.

On the other hand, in order to implement color display, each pixel uniquely displays one of the primary colors (spatial division) or each pixel alternately displays three primary colors over time (time division) so that the spatial or temporal matching of these three primary colors is performed. To recognize the desired color. Examples of primary colors include red, green and blue.

2 shows an equivalent circuit for one pixel of a liquid crystal display as an example of spatial division. The color filter CF may be formed in a portion of the common electrode CE of the second display panel 200 to face the pixel electrode PE of the first display panel 100. Each pixel, for example, a pixel connected to an i-th (i = 1, 2, ..., n) gate line Gi and a j-th (j = 1, 2, ..., m) data line D _j is connected to a signal line ( A switching element Q connected to G _i , D _j ), and a liquid crystal capacitor Clc and a storage capacitor Cst connected thereto are included. The holding capacitor Cst can be omitted as necessary.

Meanwhile, the gate driver 400 of FIG. 1 is connected to the gate lines G ₁ -G _n so that the gate-on voltage Von and gate-off from the gate on / off voltages Von and Voff generators (not shown) are shown. A gate signal composed of a combination of the voltages Voff is applied to the gate lines G ₁ -G _n .

The gate driver 400 includes a plurality of gate driving chips, and gates the gate-on voltage Von from a gate on / off voltage generator (not shown) according to the gate control signal CONT1 from the signal controller 600. ray was applied to (G ₁ -G _n) turns on the switching device (Q) of Fig. 2 are connected to a gate line (G ₁ -G _n). Then, the data signal applied to the data lines D ₁ -D _m is applied to the pixel PX through the switching element Q turned on.

The difference between the voltage of the data signal applied to the pixel PX and the common voltage Vcom is charged in the liquid crystal capacitor Clc to serve as the pixel voltage. The arrangement of the liquid crystal molecules varies according to the magnitude of the pixel voltage. Accordingly, the polarization of the light passing through the liquid crystal layer 150 changes, thereby displaying an image.

The data driver 500 includes a plurality of data driver chips, and is connected to the data lines D ₁ -D _m of the liquid crystal panel 300 to select the gray voltage corresponding to the data from the gray voltage generator 800. Then, the selected gray voltage is applied to the pixel as a data voltage. Here, when the gray voltage generator 800 does not provide all the voltages for all grays but only the basic gray voltages, the data driver 500 divides the basic gray voltages to generate gray voltages for all grays. The data voltage can be selected from these.

The signal controller 600 receives the input image signals R, G, and B and an input control signal for controlling the display thereof from an external graphic controller (not shown). Examples of the input control signal include a vertical sync signal Vsync, a horizontal sync signal Hsync, a main clock MCLK, and a data enable signal DE.

The signal controller 600 generates a gate control signal CONT1 and a data control signal CONT2 based on the input image signals R, G, and B and the input control signal, and generates the gate control signal CONT1 by the gate driver 400. ), The data control signal CONT2 and the gamma-compensated video signal DAT 'are transmitted to the data driver 500. The gamma compensated internal image signal DAT ′ is an image signal obtained by gamma compensation of the input image signals R, G, and B according to a region of the liquid crystal panel 300 on which the input image signals R, G, and B are to be displayed. to be.

In addition, the signal controller 600 stores the memory according to the region selection signal ASS which is a combination of the first region signal AS1 provided from the gate driver 400 and the second region signal AS2 provided from the data driver 500. The gamma compensation data AGD is provided from the area 700, and gamma compensation of the input image signals R, G, and B is performed. Here, the first region signal AS1 provided from the gate driver 400 is a signal for designating a row region group in the liquid crystal panel in which a plurality of regions are divided in a matrix form, and the second region signal AS2 provided from the data driver 500. ) Is a signal specifying a group of thermal regions. In addition, the row region group refers to a set of pixels that receive a gate signal from one gate driving chip or a plurality of gate driving chips, and the column region group receives data signals from one data driving chip or a plurality of data driving chips. Means a set of pixels.

Meanwhile, a method of dividing the liquid crystal panel 300 into a plurality of areas and selecting one of the plurality of areas by combining the first area signal AS1 and the second area signal AS2 is illustrated in FIGS. 3 and 4. It will be described later with reference to.

Since the gamma-compensated internal image signal DAT 'for each region of the liquid crystal panel 300 is displayed on the liquid crystal panel 300 through the data driver 500, the luminance uniformity is increased, so that an excellent image quality can be obtained. Operation of the operation 600 and gamma compensation for each region will be described later with reference to FIG. 5.

Gamma compensation data for each area of the liquid crystal panel 300 is stored in the memory 700. That is, the luminance of each region of the liquid crystal panel 300 is measured, and a gamma compensation lookup table for each region is generated and stored in the memory 700 in comparison with the reference gamma. The memory 700 may be an electrically erasable programmable read-only memory (EEPROM).

The gray voltage generator 800 generates a gray voltage of positive or negative polarity based on the common voltage. The gray voltage generator 800 includes a plurality of resistors connected in series between a node to which a basic gray voltage is applied and a ground, and distributes the voltage level of the driving voltage to generate the gray voltage, but is not illustrated. The internal circuit of the gray voltage generator 800 is not limited thereto, and may be variously implemented.

3 is a plan view illustrating a liquid crystal panel assembly of a liquid crystal display according to an exemplary embodiment, and FIG. 4 is a plan view illustrating a liquid crystal panel assembly of a liquid crystal display according to another exemplary embodiment.

Referring to FIG. 3, the liquid crystal panel assembly 350 may include a liquid crystal panel 300, a printed circuit board 320, a gate driver including a plurality of gate driving chips 400_1, 400_2, 400_3, and 400_4 and a plurality of data drives. The data driver includes chips 500_1, 500_2, 500_3, 500_4, 500_5, and 500_6.

The printed circuit board 320 applies the gate control signal CONT1 and the data control signal CONT2 of FIG. 1 to the data driving chips 500_1,..., 500_6 and the gate driving chips 400_1,..., 400_4. Various circuit components (not shown) are mounted to enable input and generate a gate control signal CONT1 and a data control signal CONT2.

The plurality of gate driving chips 400_1,..., 400_4 and the data driving chips 500_1,..., 500_6 are mounted on a base film 401_1,..., 401_4, 501_1,..., 501_6 of a flexible material, respectively. Input and output wirings (not shown) of gate signals and data signals are formed on one surface of (401_1, ..., 401_4, 501_1, ..., 501_6). 3 illustrates four gate driving chips 400_1,..., 400_4 and six data driving chips 500_1,..., 500_6, but the number is not limited thereto.

As shown by a dotted line, the liquid crystal panel 300 includes a row region group including a plurality of pixels receiving gate signals from one gate driving chip 400_1,..., 400_4, and one data driving chip 500_1,. , Divided into a column region group including a plurality of pixels to receive a data signal from 500_6, and regions including a plurality of pixels are divided into a matrix.

That is, when four gate driving chips 400_1,..., 400_4 and six data driving chips 500_1,..., 500_6 are used as shown in FIG. 3, the liquid crystal panel 300 includes four row area groups. It is divided into six column area groups and thus divided into 24 areas.

The 24 regions may be selected as the first region signals AS1_1,..., AS1_5 and the second region signals AS2_1,..., AS2_3. For example, region A is selected when AS1_1 and AS2_1 are low, and region B is selected when AS1_5 and AS2_3 are high. Here, the first region signals AS1_1,..., AS1_5 and the second region signals AS2_1,..., AS2_3 may start operation of the adjacent gate driving chips 400_1,..., 400_4 and the data driving chips 500_1,..., 500_6. It is a carry signal indicating. However, the present invention is not limited to the Kerry signal and may be a signal provided by the gate driver 400 and the data driver 500 of FIG. 1 as a signal for selecting one region from among the plurality of regions divided on the liquid crystal panel 300. .

In this way, one region is selected, the input image signal is gamma-compensated according to the gamma compensation data corresponding to the selected region, and the gamma-compensated internal image signal is applied to the pixel, which is one pixel of the selected region. Corresponds to That is, the input image signals R, G, and B of FIG. 1 are gamma-compensated according to the region where the pixel to which the input image signals R, G, and B are to be applied are located, and the gamma-compensated internal image signal DAT '. ) Is applied to the liquid crystal panel 300 so that the luminance uniformity is improved.

Referring to FIG. 4, the liquid crystal panel 300 ′ of the liquid crystal panel assembly 350 ′ according to another embodiment of the present invention is divided into six regions.

One region includes a plurality of pixels that receive gate signals and data signals from two gate driving chips 400_1 to 400_4 and two data driving chips 500_1 to 500_6. The C region is selected when the carry signal AS2 'of the second gate driving chip 400_2 is low and the carry signal AS1'_1 of the second data driving chip 500_2 is high. The region is selected when the carry signal AS2 'of the second gate driving chip 400_2 is high and the carry signal AS1'_2 of the fourth data driving chip 500_4 is high.

As described above, the gate driving chip groups 400a and 400b including at least one gate driving chip 400_1,..., And 400_4 and the data driving chip group including at least one or more data driving chips 500_1,..., 500_6 ( The area may be divided into pixels that receive the gate signal and the data signal from 500a, 500b, and 500c.

As shown in FIG. 3 and FIG. 4, the liquid crystal panels 300 and 300 ′ may be divided into a plurality of regions, and the number of divided regions may include the size, gate, and data of the liquid crystal panels 300 and 300 ′. It may vary depending on the number of driving chips.

5 is a block diagram illustrating a signal controller and gamma compensation for each region of a liquid crystal display according to example embodiments.

Referring to FIG. 5, the signal controller 600 includes an area selection signal generator 610, a memory controller 620, and a gamma compensator 630.

The region selection signal generator 610 receives the first and second region signals AS1 and AS2 from the gate driver and the data driver to select a specific region of the liquid crystal panel. A region selection signal ASS is generated. For example, each of the six regions of FIG. 4 may be specified by an area select signal (ASS) of 3 bits, wherein the most significant bit of the 3 bits is 0 or 1 as a bit specifying a row region group, and the next two bits As the bit designating the column region group, the bits are 00, 01, and 10, and thus six regions may correspond to 000, 001, 010, 100, 101, and 110, respectively. In addition, the region selection signal ASS may be generated in various ways.

The memory controller 620 outputs a gamma selection signal GSS according to the region selection signal ASS, and receives gamma data AGD for each region from the memory 700. The gamma selection signal GSS is a signal for selecting one gamma data AGD according to the region selection signal ASS from the plurality of region-specific gamma data stored in the memory 700.

The gamma compensator 630 gamma-compensates the external image signal DAT according to gamma data AGD for each region, and provides the gamma compensated image signal DAT 'to a data driver (not shown). Here, the external video signal DAT includes red, green, and blue which are input video signals R, G, and B.

That is, the external image signal DAT is gamma-compensated through gamma compensation data AGD for each region according to a region to be displayed on the liquid crystal panel (not shown), and the gamma-compensated image signal DAT 'is a liquid crystal panel (not shown). ), It is displayed as a predetermined image, so that the luminance uniformity becomes high and excellent image quality can be obtained.

A driving method of such a liquid crystal display will be described below with reference to FIGS. 1 to 5.

First, a liquid crystal panel 300 divided into a plurality of regions arranged in a matrix form is provided.

Next, a first region signal AS1 for designating a row region group corresponding to a predetermined row region of the matrix and a second region signal AS2 for designating a column region group corresponding to a predetermined column region of the matrix are input. In response thereto, an area selection signal ASS for selecting one of the plurality of areas is generated.

Here, the first area signal AS1 may be a Kerry signal indicating the start of the operation of the gate driving chips 400_1,..., 400_4, and the second area signal AS2 may be an operation of the data driving chips 500_1,..., 500_6. It may be a carry signal indicating a start.

Also, as illustrated in FIG. 3, the region includes a row region including pixels receiving gate signals and data signals from one gate driving chip 400_1,..., 400_4 and the data driving chips 500_1,..., 500_6. As shown in FIG. 4, pixels that receive a gate signal and a data signal from the gate driving chip groups 400a and 400b and the data driving chip groups 500a, 500b and 500c may be divided into a group and a column region group. It can also be divided into a row area group and a column area group.

Next, the gamma compensation data AGD corresponding to the selected area is selected from the memory 700 in which gamma compensation data for each area is stored according to the area selection signal ASS. The memory 700 may be an ypyrom.

The external image signal DAT is gamma compensated according to the gamma compensation data AGD. The external image signal DAT may be red, green, or blue which are input image signals R, G, and B, and provides a gamma-compensated image signal DAT 'to the data driver 500.

In the driving method of the liquid crystal display, an external image signal is gamma-compensated for each region of the liquid crystal panel to display a predetermined image through the data driver, thereby increasing luminance uniformity and providing excellent image quality.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the liquid crystal display of the present invention and its driving method as described above, excellent image quality can be obtained.

Claims (10)

A plurality of regions are divided into a matrix form, the region comprising a liquid crystal panel comprising a plurality of pixels; A gate driver configured to provide a first region signal specifying a row region group corresponding to a predetermined row region of the matrix; A data driver configured to provide a second region signal specifying a column region group corresponding to a predetermined column region of the matrix; An area selection signal generator configured to receive the first and second area signals and provide an area selection signal for selecting one of the plurality of areas; A memory in which gamma compensation data is stored for each area; A memory controller configured to output gamma compensation data of the selected region provided from the memory according to the region selection signal; And And a gamma compensation unit configured to gamma-compensate an external image signal according to the gamma compensation data and convert the external image signal into an internal image signal. The method of claim 1, Each of the gate and data driver includes a plurality of gate and data driver chips, wherein each gate driver chip provides a gate signal to a plurality of pixels arranged in a row direction, and each of the data driver chips is arranged in a column direction. A liquid crystal display device that provides a data signal to a plurality of pixels. The method of claim 2, Each of the plurality of gate and data driving chips is divided into at least one gate and data driving chip group, and the first and second region signals respectively indicate an operation start of the adjacent gate driving chip group and the data driving chip group. A liquid crystal display device that is a Kerry signal. The method of claim 1, Each of the gate and data driver includes a plurality of gate and data driver chips, and each of the gate and data driver chips is divided into at least one gate and data driver chip group, and the row region group is the gate driver chip. And a plurality of pixels receiving a gate signal from a group, and wherein the column region group includes a plurality of pixels receiving a data signal from the data driving chip group. The method of claim 1, And the memory is ypyrom. Providing a liquid crystal panel in which a plurality of regions are divided in a matrix form, the regions including a plurality of pixels; Receiving a first region signal specifying a row region group corresponding to a predetermined row region of the matrix and a second region signal specifying a column region group corresponding to a predetermined column region of the matrix, and receiving one of the plurality of regions Generating an area selection signal for selecting an area; Selecting gamma compensation data corresponding to the selected area from a memory in which gamma compensation data is stored for each area according to the area selection signal; And And converting an external image signal into an internal image signal by gamma compensation according to the gamma compensation data. The method of claim 6, Each of the gate and data driver includes a plurality of gate and data driver chips, wherein each gate driver chip provides a gate signal to a plurality of pixels arranged in a row direction, and each of the data driver chips is arranged in a column direction. A driving method of a liquid crystal display device for providing a data signal to a plurality of pixels. The method of claim 7, wherein Each of the plurality of gate and data driving chips is divided into at least one gate and data driving chip group, and the first and second region signals respectively indicate an operation start of the adjacent gate driving chip group and the data driving chip group. A method of driving a liquid crystal display device that is a Kerry signal. The method of claim 6, Each of the gate and data driver includes a plurality of gate and data driver chips, and each of the gate and data driver chips is divided into at least one gate and data driver chip group, and the row region group is the gate driver chip. And a plurality of pixels receiving a gate signal from a group, and wherein the column region group includes a plurality of pixels receiving a data signal from the data driving chip group. The method of claim 6, And the memory is two pyrom.

Images