KR20070064062A - Repairing system for liquid crystal display - Google Patents

Abstract

A system for repairing an LCD(Liquid Crystal Display) is provided to prevent a display spot from being recognized through a screen, by previously inputting the correcting gradation, which has the same brightness as a normal area of the screen, to a spot area of the screen. A photographing unit(21) photographs a screen of an LCD(11). An electronic unit(31) is connected to the photographing unit and the LCD, wherein the electronic unit analyzes brightness data of the screen. The screen of the LCD is divided into a first area and a second area having different gamma curves. The electronic unit extracts a second gradation group according to the gamma curve of the second area on the basis of a first gradation group according to the gamma curve of the first area.

Description

Repair system for liquid crystal display {REPAIRING SYSTEM FOR LIQUID CRYSTAL DISPLAY}

With reference to the accompanying drawings will be described in detail the embodiments of the present invention to make the present invention clear.

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 a liquid crystal display according to an exemplary embodiment of the present invention.

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

4 is a graph illustrating a gamma curve used in a repair system of a liquid crystal display according to an exemplary embodiment of the present invention.

<Description of Drawing>

3: liquid crystal layer 11: liquid crystal display device

21: recording device 31: computer

41: Memory Writer 100: Lower Display Panel

191: pixel electrode 200: upper display panel

230: color filter 270: common electrode

300: liquid crystal panel assembly 400: gate driver

500: data driver 600: signal controller

750: Memory 800: Gray voltage generator

R, G, B: Input image data DE: Data enable signal

MCLK: Main Clock Hsync: Horizontal Sync Signal

Vsync: Vertical Sync Signal CONT1: Gate Control Signal

CONT2: data control signal DAT: digital video signal

Clc: Liquid Crystal Capacitor Cst: Keeping Capacitor

Q: switching device

The present invention relates to a repair system of a liquid crystal display device.

A typical liquid crystal display (LCD) includes two display panels provided with pixel electrodes and a common electrode, and a liquid crystal layer having dielectric anisotropy interposed therebetween. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs) to receive data voltages one by one in sequence. The common electrode is formed over the entire surface of the display panel and receives a common voltage. The pixel electrode, the common electrode, and the liquid crystal layer therebetween form a liquid crystal capacitor, and the liquid crystal capacitor becomes a basic unit forming a pixel together with a switching element connected thereto.

In such a liquid crystal display, a voltage is applied to two electrodes to generate an electric field in the liquid crystal layer, and the intensity of the electric field is adjusted to adjust the transmittance of light passing through the liquid crystal layer to obtain a desired image. In this case, in order to prevent degradation caused by an electric field applied to the liquid crystal layer for a long time, the polarity of the data voltage with respect to the common voltage is inverted frame by frame, row by pixel, or pixel by pixel.

Such a liquid crystal display includes a display panel including a pixel including a switching element, a display signal line, a gate driver to turn on / off a switching element of a pixel by sending a gate signal to a gate line among the display signal lines, and to generate a plurality of gray voltages. A gray voltage generator, a data driver which selects a voltage corresponding to the image data among the gray voltages as a data voltage and applies a data voltage to the data lines of the display signal lines, and a signal controller to control the gray voltages.

On the other hand, the liquid crystal display checks the uniformity of the screen in the completion of the product to check whether a certain portion of the screen is darker than other portions.

These stains damage the uniformity of the screen and are eventually treated as bad.

Accordingly, the technical problem to be achieved by the present invention is to provide a repair system for a liquid crystal display device capable of removing such spots.

According to an aspect of the present invention, a repair system for a liquid crystal display device includes a liquid crystal display device, a photographing device for photographing a screen of the liquid crystal display device, and a liquid crystal display device and the photographing device. And an electronic device for analyzing luminance data of the screen, wherein the screen of the liquid crystal display is divided into a first area and a second area having different gamma curves, and the electronic device is connected to the gamma curve of the first area. The second gray level group according to the gamma curve of the second region is extracted based on the first gray level group.

In this case, the gamma curve of the first region may be located above the gamma curve of the second region.

In addition, the luminance according to the second gradation group may represent the same luminance as the luminance according to the first gradation group.

A part including the highest gray level of the second gray level group may be substantially the same as a part including the highest gray level of the first gray level group, and the rest of the second gray level group may be larger than the rest of the first gray level group. have.

The electronic device may output the first grayscale group and the second grayscale group corresponding thereto in the form of a look-up table. The liquid crystal display may further include a memory configured to store the look-up table. It may include.

The system may further include a memory writer for inputting the lookup table into the memory.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right on" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

First, a liquid crystal display according to an exemplary embodiment 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 an exemplary embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of one pixel of the liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel assembly 300, a gate driver 400, a data driver 500, and a data driver 500 connected thereto. The gray voltage generator 800 connected to the signal generator 500 and a signal controller 600 for controlling the gray voltage generator 800 are included.

The liquid crystal panel assembly 300 may include a plurality of signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels PX connected to the plurality of signal lines G ₁ -G _n , D ₁ -D _m , and arranged in a substantially matrix form. Include. In contrast, in the structure shown in FIG. 2, the liquid crystal panel assembly 300 includes lower and upper panels 100 and 200 facing each other and a liquid crystal layer 3 interposed therebetween.

The signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”) and a plurality of data lines for transmitting a data signal ( D ₁ -D _m ). The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each pixel PX, for example, the pixel PX connected to the i-th (i = 1, 2,, n) gate line G _i and the j-th (j = 1, 2,, m) data line Dj. ) Includes a switching element Q connected to the signal line G _i D _j , a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto. Holding capacitor Cst can be omitted as needed.

The switching element Q is a three-terminal element of a thin film transistor or the like provided in the lower panel 100, the control terminal of which is connected to the gate line G _i , and the input terminal of which is connected to the data line D _j . The output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The liquid crystal capacitor Clc has two terminals, the pixel electrode 191 of the lower panel 100 and the common electrode 270 of the upper panel 200, and the liquid crystal layer 3 between the two electrodes 191 and 270 is a dielectric material. Function as. The pixel electrode 191 is connected to the switching element Q, and the common electrode 270 is formed on the front surface of the upper panel 200 and receives the common voltage Vcom. Unlike in FIG. 2, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 191 and 270 may be formed in a linear or bar shape.

The storage capacitor Cst, which serves as an auxiliary part of the liquid crystal capacitor Clc, is formed by overlapping a separate signal line (not shown) and the pixel electrode 191 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage Vcom is applied to the separate signal line. However, the storage capacitor Cst may be formed such that the pixel electrode 191 overlaps the front gate line directly above the insulator.

On the other hand, in order to implement color display, each pixel PX uniquely displays one of the primary colors (spatial division) or each pixel PX alternately displays the primary colors over time (time division). The desired color is recognized by the spatial and temporal sum of these primary colors. Examples of the primary colors include three primary colors such as red, green, and blue. FIG. 2 illustrates that each pixel PX includes a color filter 230 representing one of the primary colors in an area of the upper panel 200 corresponding to the pixel electrode 191 as an example of spatial division. Unlike FIG. 2, the color filter 230 may be formed above or below the pixel electrode 191 of the lower panel 100.

At least one polarizer (not shown) for polarizing light is attached to an outer surface of the liquid crystal panel assembly 300.

Referring back to FIG. 1, the gray voltage generator 800 generates two sets of gray voltage sets (or reference gray voltage sets) related to the transmittance of the pixel PX. One of the two sets has a positive value for the common voltage Vcom and the other set has a negative value.

A gate driver 400, a gate line (G ₁ -G _n) and is connected to the gate turn-on voltage (Von), and a gate signal consisting of a combination of a gate-off voltage (Voff), a gate line (G ₁ of the liquid crystal panel assembly 300 -G _n ).

The data driver 500 is connected to the data lines D ₁ -D _m of the liquid crystal panel assembly 300 and selects a gray voltage from the gray voltage generator 800 and uses the data line D ₁ as a data signal. -D _m ). However, when the gray voltage generator 800 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 500 divides the reference gray voltages to divide the gray voltages for all grays. Generate and select the data signal from it.

The signal controller 600 includes a memory 750 and controls the gate driver 400, the data driver 500, and the like.

Each of the driving devices 400, 500, 600, and 800 may be mounted directly on the liquid crystal panel assembly 300 in the form of at least one integrated circuit chip, or may be a flexible printed circuit film (not shown). It may be mounted on the liquid crystal panel assembly 300 in the form of a tape carrier package (TCP) or mounted on a separate printed circuit board (not shown). Alternatively, these driving devices 400, 500, 600, and 800 may be integrated in the liquid crystal panel assembly 300 together with the signal lines G ₁ -G _n , D ₁ -D _m and the thin film transistor switching element Q. It may be. In addition, the driving devices 400, 500, 600, and 800 may be integrated into a single chip, in which case at least one of them or at least one circuit element constituting them may be outside the single chip.

Next, the operation of the liquid crystal display will be described in detail.

The signal controller 600 receives 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 properly processes the input image signals R, G, and B according to operating conditions of the liquid crystal panel assembly 300 based on the input image signals R, G, and B and the input control signal, and controls the gate. After generating the signal CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 400, and the data control signal CONT2 and the processed image signal DAT are transmitted to the data driver 500. Export to).

The gate control signal CONT1 includes a scan start signal STV indicating a scan start and at least one clock signal controlling an output period of the gate-on voltage Von. The gate control signal CONT1 may also further include an output enable signal OE that defines the duration of the gate-on voltage Von.

The data control signal CONT2 is a load for applying a data signal to the horizontal synchronization start signal STH and the data lines D ₁ -D _m indicating the start of image data transmission for the pixels PX in one row [bundling]. Signal LOAD and data clock signal HCLK. The data control signal CONT2 is also an inverted signal that inverts the voltage polarity of the data signal relative to the common voltage Vcom (hereinafter referred to as " polarity of the data signal " by reducing the " voltage polarity of the data signal for the common voltage &quot;) RVS) may be further included.

According to the data control signal CONT2 from the signal controller 600, the data driver 500 receives the digital image signal DAT for the pixels PX in one row (bundling), and each digital image signal DAT. By converting the digital image signal DAT into an analog data signal by selecting a gray scale voltage corresponding to), it is applied to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage Von to the gate lines G ₁ -G _n in response to the gate control signal CONT1 from the signal controller 600, thereby applying the gate lines G ₁ -G _n . Turn on the switching element (Q) connected to. 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 shown as the charging voltage of the liquid crystal capacitor Clc, that is, the pixel voltage. The arrangement of the liquid crystal molecules varies depending on the magnitude of the pixel voltage, thereby changing the polarization of light passing through the liquid crystal layer 3. The change in polarization is represented by a change in transmittance of light by a polarizer attached to the display panel assembly 300.

This process is repeated in units of one horizontal period (also referred to as "1H" and equal to one period of the horizontal sync signal Hsync and the data enable signal DE), thereby all the gate lines G ₁ -G _n. ), The gate-on voltage Von is sequentially applied to the data signal to all the pixels PX, thereby displaying an image of one frame.

When one frame ends, the state of the inversion signal RVS applied to the data driver 500 is controlled so that the next frame starts and the polarity of the data signal applied to each pixel PX is opposite to the polarity of the previous frame. "Invert frame"). In this case, the polarity of the data signal flowing through one data line is changed (eg, row inversion and point inversion) or the polarity of the data signal applied to one pixel row is different depending on the characteristics of the inversion signal RVS within one frame. (E.g. column inversion, point inversion).

Next, a repair system of a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

3 is a diagram illustrating an example of a repair system for a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is a graph illustrating a gamma curve used in the repair system for a liquid crystal display according to an exemplary embodiment of the present invention. to be.

Referring to FIG. 3, a repair system of a liquid crystal display according to an exemplary embodiment of the present invention may include a liquid crystal display 11, a photographing apparatus 21, a computer 31, and a memory writer connected thereto ( 41).

The liquid crystal display 11 displays a screen corresponding to a predetermined gray scale, and a portion of the screen, which is darker than the normal region A and the normal region A, is displayed.

The photographing apparatus 21 may be a CCD camera, and photographs the normal area A and the spot B, converts them into luminance information such as voltage, and sends them to the computer 31.

The computer 31 extracts a constant gradation value based on this luminance information, which will be described in detail.

FIG. 4 is a gamma curve representing luminance according to gray scale, and the gamma curve represented by the spot B is located below the gamma curve represented by the normal region A. FIG. For this reason, when the screen corresponding to the gray scale g1 is displayed on the liquid crystal display 11, the normal area A represents the luminance Y1, while the spot B represents the lower luminance Y2. The difference between the two gamma curves is eventually perceived by the human eye in the form of stains.

At this time, in the gamma curve represented by the unevenness B, the gray scale showing the same brightness Y1 as the normal region A is "g ₁ ""(hereinafter referred to as" correction gray scale "). Therefore, in the screen area in which the spot B appears, when the correction gray level g2 is input instead of the gray level g ₁ (hereinafter referred to as 'normal gray level'), the spot B is displayed with the same luminance as the normal area A. It will not be recognized.

Therefore, when 8-bit image data R, G, and B are input to the liquid crystal display device 11, 256 gray levels are required from 0 gray scale to 255 gray scales. A correction gradation corresponding to the gradation can be obtained.

At this time, the correction gradation corresponding to the normal gradation is larger than the normal gradation as described above. Therefore, the corrected gray scale may exceed the highest gray scale at 255 gray scales or the previous gray scales. In this case, for example, after 250 gradations, it is preferable to make the correction gradation equal to the normal gradation. This is because the human eye easily recognizes stains at low gradations of low brightness, but does not recognize stains at low gradations of high brightness.

The computer 31 inputs the data for the correction gradation thus obtained into the memory 750 through the memory writer 41 shown in FIG. 3 in the form of a look-up table.

In this case, for example, in the case of a liquid crystal display for a TV, the memory 750 may be directly mounted, and in the case of a liquid crystal display for a monitor used with a computer, the software may be configured to apply a lookup table. Can be provided.

In this way, the correction gradation which shows the same luminance as the normal region can be input to the spot in advance so that the spot is not visible.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (7)

Liquid crystal display, A photographing apparatus for photographing the screen of the liquid crystal display, and An electronic device connected to the liquid crystal display and the photographing device to analyze luminance data of the screen. Including, The screen of the liquid crystal display is divided into a first region and a second region having different gamma curves. The electronic device extracts a second grayscale group according to the gamma curve of the second region based on the first grayscale group according to the gamma curve of the first region. Repair system for liquid crystal displays. In claim 1, And a gamma curve of the first region is above the gamma curve of the second region. In claim 2, And a luminance according to the second gradation group exhibits the same luminance as that of the first gradation group. In claim 3, Part of the second grayscale group including the highest grayscale is substantially the same as a portion including the highest grayscale of the first grayscale group, and the rest of the second grayscale group is larger than the rest of the first grayscale group. Repair system for indicators. In claim 4, And the electronic device outputs the first grayscale group and the second grayscale group corresponding thereto in the form of a look-up table. In claim 5, And the liquid crystal display device includes a memory for storing the lookup table. In claim 6, The system further comprises a memory writer for inputting the lookup table into the memory.

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