KR20050104954A - Liquid crystal display and method of modifying gray signals - Google Patents

Abstract

The present invention relates to a liquid crystal display device, wherein the liquid crystal display device compares a previous video signal, a current video signal, and a next video signal supplied from a plurality of pixels and signal sources, and corrects the current video signal according to a comparison result. And a data driver for converting the corrected image signal from the image signal corrector into a corresponding data voltage and supplying the pixel to the corresponding data voltage. According to the present invention, since the cases are classified according to the characteristics of the difference between the previous video signal, the current video signal, and the next video signal, and corrected in a different manner according to each case, the correcting operation is performed according to the characteristics of the difference, thereby improving the response speed. In addition, it is possible to prevent a defect of the LCD screen, such as flicker phenomenon.

Description

Liquid Crystal Display and Image Signal Correction Method {LIQUID CRYSTAL DISPLAY AND METHOD OF MODIFYING GRAY SIGNALS}

The present invention relates to a liquid crystal display (LCD) and an image signal correction method, and more particularly, to a liquid crystal display and a video signal correction method for correcting an image signal from a signal source.

A general liquid crystal display device includes two display panels and a liquid crystal layer having dielectric anisotropy interposed therebetween. The desired image is obtained by applying an electric field to the liquid crystal layer and adjusting the intensity of the electric field to adjust the transmittance of light passing through the liquid crystal layer. Such liquid crystal displays are typical among portable flat panel displays (FPDs) that are easy to carry. Among them, TFT-LCDs using thin film transistors (TFTs) as switching elements are mainly used.

As such TFT-LCDs are widely used not only as display devices of computers but also as display screens of televisions, there is an increasing need to implement moving images. However, the conventional TFT-LCD has a disadvantage in that it is difficult to implement a moving picture because the response speed of the liquid crystal is slow.

That is, since the response speed of the liquid crystal molecules is slow, it takes some time for the voltage charged in the liquid crystal capacitor to reach the target voltage, that is, the voltage at which the desired luminance can be obtained, and this time is previously charged in the liquid crystal capacitor. It depends on the difference between the voltages present. Therefore, for example, when the difference between the target voltage and the previous voltage is large, applying only the target voltage from the beginning may not reach the target voltage during the time that the switching element is turned on.

In order to improve the response speed of the liquid crystal in a driving manner without changing the properties of the liquid crystal, a DCC (dynamic capacitance compensation) method has been proposed. That is, the DCC method uses the fact that the higher the voltage across the liquid crystal capacitor is, the faster the charging speed is. The data voltage applied to the corresponding pixel (actually, the difference between the data voltage and the common voltage is assumed to be 0 for convenience). Higher than the target voltage shortens the time it takes for the voltage charged in the liquid crystal capacitor to reach the target voltage.

As described above, when the video signal is corrected by the DCC method, the response speed may be improved, but flicker may occur. 1 is a waveform diagram showing a luminance response to an image signal corrected by a DCC method. The waveform of FIG. 1 is a response waveform when the video signal of "0" gray is continuously applied and the video signal of "128" gray is applied. Here, the corrected video signal by the DCC becomes " 208 ", and as shown in Fig. 1, the target luminance is reached within one frame, but then the target luminance is approached again after the luminance drops by about 90% in the next frame. This effect causes flicker, especially in the low gradation range.

Meanwhile, there is a screen representing a wire frame among screens on which a computer aided design (CAD) program designed using a computer is executed. The wire frame represents the shape of a three-dimensional object as a set of line segments. However, the flicker phenomenon occurs when the object represented by the wire frame on the screen is moved left or right or zooms in and out. Flicker that occurs in such a case is called wire frame flicker. In particular, a wire frame flicker phenomenon occurs severely in a panel employing a patterned vertical alignment (PVA) mode.

2 is a diagram illustrating a test screen of a liquid crystal display. As shown in FIG. 2, when the red square box is moved diagonally as shown in the arrow direction on the gray-based screen, the direction opposite to the moving direction of the square box is indicated as a circle at the bottom left and top right corners of the box. Cyan tail appears. The cyan tail appears where it changes from gray to red to gray. In this region, the video signal for the green (G) and blue (B) pixels changes from 128 → 0 → 128. When the video signal changes from 0 to 128, the video signal corrected by the DCC becomes " 208 ", and as shown by the circle shown in Fig. 3, the overshoot exceeding the target luminance appears very large. Therefore, the green and blue pixels display luminance higher than the target luminance, and as a result, the above-mentioned cyan tail is visible.

In order to correct an image signal using the DCC method, preset correction image data is used. The correction image data is set to an image signal value whose response characteristics are improved as desired when the gray level in a stable state is maintained and converted to the target gray level. . However, when the above red box is moved, it is not converted from the stable gradation to the target gradation, but is converted to the target gradation "128" while maintaining "0" gradation only for one frame. Abnormal overshoot has occurred as a result of using the corrected image data " 208 "

This phenomenon will be described with reference to FIGS. 4A to 4C in terms of liquid crystal capacitance and pixel voltage.

4A to 4C show the relationship between the liquid crystal capacitance and the pixel voltage. 4A shows the liquid crystal capacitance C ₁₂₈ and the pixel voltage V ₁₂₈ when maintaining the " 128 " gray scale. 4B illustrates a case in which the pixel voltage V ₀ corresponding to the “0” gray scale is applied in the state of FIG. 4A. At this time, the pixel electrode has an amount of charge Q ₀ = C ₁₂₈ × V ₀ . The liquid crystal molecules move by the pixel voltage V ₀ , and the liquid crystal capacitance also changes. On the other hand, the switching element, the transistor, is turned on only for a very short time and off until the end of one frame compared to the time when one frame is maintained. However, when the switching element is turned off, the amount of charge Q ₀ stored in the pixel should not change. Therefore, as the liquid crystal capacitance changes, the pixel voltage also changes in order to maintain the charge amount Q ₀ . 4C shows the voltage change at the end of the frame to which the pixel voltage V ₀ is applied. The pixel voltage changes from V ₀ to V _{G ′} due to the liquid crystal capacitance C _{G ′ that} is finally changed at the end of the frame. The input of the DCC corrected image signal "208" in this state means that an excessively corrected signal is input as compared with the case where the stable state is converted from "0" gray level to "128" gray level. As a result, an overshoot exceeding the target luminance occurs, and the cyan tail is displayed on the screen.

Accordingly, an object of the present invention is to provide a liquid crystal display and an image signal correction method for preventing a defect of a liquid crystal display such as a flicker phenomenon while improving the slow response speed of the liquid crystal through image signal correction.

According to an aspect of the present invention, a liquid crystal display device includes:

A plurality of pixels,

An image signal correction unit for comparing the previous image signal, the current image signal, and the next image signal supplied from a signal source and correcting the current image signal according to a comparison result;

And a data driver which converts the corrected image signal from the image signal corrector into a corresponding data voltage and supplies the pixel to the pixel.

If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value, and the difference between the current video signal and the next video signal exceeds a second set value, based on the current video signal and the next video signal. The current video signal can be corrected.

When the difference between the previous video signal and the current video signal exceeds the first set value, the current video signal may be corrected based on the previous video signal and the current video signal.

If the difference between the previous video signal and the current video signal is less than or equal to the first setting value and the difference between the current video signal and the next video signal is less than or equal to the second setting value, the current video signal is not corrected.

If the previous video signal is the same as the current video signal and the current video signal is different from the next video signal, the current video signal is corrected based on the current video signal and the next video signal.

If the previous video signal is different from the current video signal, the current video signal is corrected based on the previous video signal and the current video signal.

If the previous video signal, the current video signal and the next video signal are the same, the current video signal is not corrected.

If the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than a second set value, based on the previous video signal and the current video signal. A first corrected video signal obtained by correcting the current video signal may be generated.

Preferably, the first corrected video signal has a smaller value among the interpolated value and the current video signal according to the previous video signal and the current video signal.

If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the previous video signal and the current video signal and the next video signal are based on the previous video signal. A second corrected video signal obtained by correcting the current video signal may be generated.

Preferably, the second corrected video signal has a value interpolated according to the previous video signal and the current video signal, a value interpolated according to the current video signal and the next video signal, and a maximum value of the current video signal. .

The previous video signal is greater than the sum of the current video signal and the first setting value and the difference between the current video signal and the next video signal is equal to or less than the second setting value;

If the current video signal is greater than the sum of the previous video signal and the first set value,

The third corrected video signal may be generated by correcting the current video signal based on the previous video signal and the current video signal.

The third corrected video signal may be a value interpolated according to the previous video signal and the current video signal.

If the difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the current video signal is greater than or equal to the next video signal, the current video signal is not corrected.

The image signal correction unit,

A frame memory which outputs the stored previous video signal and the current video signal and stores the next video signal; and

A look-up table for outputting a value of a corresponding correction parameter according to the next video signal, the previous video signal from the frame memory, and the current video signal

It is preferable to include.

The frame memory includes a first frame memory and a second frame memory,

The first frame memory outputs the current video signal and stores the next video signal,

The second frame memory may output the previous image signal and store the current image signal from the first frame memory.

The frame memory may include three frame memories, and each of the three frame memories may store the previous video signal, the current video signal, and the next video signal.

The lookup table may store a first correction variable that is predetermined according to the current image signal and the next image signal, and a second correction variable that is predetermined according to the previous image signal and the current image signal.

The lookup table,

Outputting the first correction variable when a difference between the previous video signal and the current video signal is equal to or less than a first preset value and a difference between the current video signal and the next video signal exceeds a second preset value;

When the difference between the previous video signal and the current video signal exceeds the first set value, the second correction variable may be output.

The lookup table,

Outputting the first and second correction variables when a difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the next video signal is larger than the current video signal;

When the difference between the previous video signal and the current video signal is greater than a first set value, the second correction variable may be output.

The lookup table includes first and second lookup tables,

The first lookup table stores the first correction parameter,

Preferably, the second lookup table stores the second correction variable.

The lookup table includes first and second lookup tables,

The first lookup table outputs a first correction variable which is predetermined according to the next video signal and the current video signal and stored in the first lookup table.

The second lookup table may output a second correction variable that is previously determined according to the current video signal and the next video signal and stored in the second lookup table.

The image signal correction unit,

A signal comparator for comparing the next video signal with the previous video signal from the frame memory and the current video signal to generate a corresponding signal according to the comparison result; and

The corrected video signal is calculated by calculating the correction variable from the lookup table, the next video signal, the previous video signal from the frame memory, and the current video signal in a manner determined according to a signal from the signal comparator. Arithmetic operators

It is preferable to further include.

The lookup table stores a first correction variable predetermined according to the current video signal and the next video signal, and a second correction variable predetermined according to the previous video signal and the current video signal.

The calculator,

If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value and the difference between the current video signal and the next video signal exceeds a second set value, the first correction variable, the current video signal, and Calculate with the next video signal,

If the difference between the previous video signal and the current video signal exceeds the first set value, the operation is performed with the second correction variable, the previous video signal and the current video signal,

When the difference between the previous video signal and the current video signal is less than or equal to the first setting value, and the difference between the current video signal and the next video signal is less than or equal to the second setting value, the current video signal is not corrected. Do.

The lookup table stores a first correction variable predetermined according to the current video signal and the next video signal, and a second correction variable predetermined according to the previous video signal and the current video signal.

The calculator,

If the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than a second set value, the second correction parameter, the previous video signal and the Operate on the current video signal,

If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the first and second correction variables, the current video signal, and the next video signal. Compute with

The previous video signal is greater than the sum of the current video signal and the first preset value, and the difference between the current video signal and the next video signal is equal to or less than the second preset value, or the current video signal is equal to the previous video signal. When the sum is greater than the sum of the first set value, the second correction variable is calculated based on the previous image signal and the current image signal.

When the difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the current video signal is greater than or equal to the next video signal, the current video signal may not be corrected.

According to another aspect of the present invention, there is provided a video signal correction method of a liquid crystal display device.

Receiving a previous video signal, a current video signal, and a next video signal,

Comparing the previous video signal with the current video signal and the next video signal, and

Correcting the current video signal according to the comparison result in the comparing step.

The comparing step,

Comparing a difference between the previous video signal and the current video signal and a first set value; and

And comparing a difference between the current video signal and the next video signal and a second set value.

The correction step,

Reading a first correction parameter predetermined according to the current video signal and the next video signal,

Preferably, the method further comprises reading a second correction parameter predetermined according to the previous video signal and the current video signal.

The comparing step,

Comparing the sum of the current video signal and the first set value with the previous video signal, and

The method may further include comparing the next video signal with the current video signal.

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 implement 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 part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" 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.

A liquid crystal display and an image signal correction method according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

5 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 6 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. 5, the liquid crystal display according to the 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 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 includes a plurality of display signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels connected to the plurality of display signal lines G ₁ -G _n , D ₁ -D _m , and arranged in a substantially matrix form. .

The display 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 data line D for transmitting a data signal. 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 includes a switching element Q connected to a display signal line G ₁ -G _n , D ₁ -D _m , and a liquid crystal capacitor C _LC and a storage capacitor C _ST connected thereto. It includes. The holding capacitor C _ST can be omitted as necessary.

The switching element Q, such as a thin film transistor, is provided in the lower panel 100, and the control terminal and the input terminal are three-terminal elements, respectively, with gate lines G ₁ -G _n and data lines D ₁ -D _m . The output terminal is connected to a liquid crystal capacitor (C _LC ) and a holding capacitor (C _ST ).

The liquid crystal capacitor C _LC has two terminals, the pixel electrode 190 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 190 and 270. It functions as a dielectric. The pixel electrode 190 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 a common voltage V _com . Unlike in FIG. 6, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 190 and 270 may be formed in a linear or bar shape.

The storage capacitor C _ST , which serves as an auxiliary part of the liquid crystal capacitor C _LC , is formed by overlapping a separate signal line (not shown) and the pixel electrode 190 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage V _com is applied to this separate signal line. However, the storage capacitor C _ST may be formed such that the pixel electrode 190 overlaps the front end gate line directly above the insulator.

On the other hand, to implement color display, each pixel uniquely displays one of the three primary colors (spatial division) or each pixel alternately displays the three primary colors over time (time division) so that the desired color can be selected by the spatial and temporal sum of these three primary colors. To be recognized. 2 shows that each pixel includes a red, green, or blue color filter 230 in a region corresponding to the pixel electrode 190 as an example of spatial division. Unlike FIG. 2, the color filter 230 may be formed above or below the pixel electrode 190 of the lower panel 100.

A polarizer (not shown) for polarizing light is attached to an outer surface of at least one of the two display panels 100 and 200 of the liquid crystal panel assembly 300.

The gray voltage generator 800 generates two sets of gray voltages related to the transmittance of the pixel. One of the two sets has a positive value for the common voltage (V _com ) and the other set has a negative value.

The gate driver 400 is connected to the gate lines G ₁ -G _n of the liquid crystal panel assembly 300 to receive a gate signal formed by a combination of a gate on voltage V _on and a gate off voltage V _off from the outside. It is applied to the gate lines G ₁ -G _n and usually consists of a plurality of integrated circuits.

The data driver 500 is connected to the data lines D ₁ -Dm of the liquid crystal panel assembly 300 to select the gray voltage from the gray voltage generator 800 and apply the gray voltage to the pixel as a data signal. Is made of.

The plurality of gate driving integrated circuits or data driving integrated circuits may be mounted in a tape carrier package (TCP) (not shown) in the form of a chip to attach the TCP to the liquid crystal panel assembly 300, or may be advantageous without using TCP. These integrated circuit chips may be directly attached onto a substrate (chip on glass, COG mounting method), and circuits performing the same functions as those integrated circuit chips may be directly mounted on the liquid crystal panel assembly 300 together with thin film transistors of pixels. It may be.

The signal controller 600 controls operations of the gate driver 400 and the data driver 500.

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

The signal controller 600 may control the input image signals R, G, and B and their display from an external graphic controller (not shown), for example, a vertical sync signal V _sync and a horizontal sync signal. (H _sync ), a main clock (MCLK), a data enable signal (DE) is provided. The signal controller 600 properly processes the image signals R, G, and B according to the 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 control signal. After generating the CONT1 and the data control signal CONT2 and the like, the gate control signal CONT1 is sent to the gate driver 400 and the data control signal CONT2 and the processed image signals R ', G', and B 'are processed. ) Is sent to the data driver 500. The image signal processing method in the signal controller 600 will be described in detail later.

The gate control signal (CONT1) includes a gate-on voltage vertical synchronization start signal (STV) for instructing the start of output of the (V _on), the gate-on voltage gated clock signal that controls the output timing of the (V _on) (CPV) and the gate-on An output enable signal OE or the like that defines the duration of the voltage V _on .

The data control signal CONT2 is a load for applying a corresponding data voltage to the horizontal synchronization start signal STH indicating the start of input of the image data R ', G', and B 'and the data lines D ₁ -D _m . Signal LOAD, inverted signal RVS and data that inverts the polarity of the data voltage with respect to common voltage V _com (hereinafter referred to as " polarity of data voltage " by reducing " polarity of data voltage with respect to common voltage "). Clock signal HCLK and the like.

The data driver 500 sequentially receives and shifts image data R ', G', and B 'of pixels in a row according to the data control signal CONT2 from the signal controller 600, and the gray voltage generator The image data R ', G', B 'is converted into the corresponding data voltage by selecting the gray voltage corresponding to each of the image data R', G ', and B' among the gray voltages from the 800. This is applied to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage V _on 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. ) Turns on the switching element Q connected thereto, so that the data voltage applied to the data lines D ₁ -D _m is applied to the corresponding pixel through the turned-on switching element Q.

The difference between the data voltage applied to the pixel and the common voltage V _com is shown as the charging voltage of the liquid crystal capacitor C _LC , that is, the pixel voltage. The arrangement of the liquid crystal molecules varies according to 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 (not shown) attached to the display panels 100 and 200.

After one horizontal period (or “1H”) (one period of the horizontal sync signal H _sync , the data enable signal DE, and the gate clock CPV), the data driver 500 and the gate driver 400 are next. The same operation is repeated for the pixels in the row. In this manner, the gate-on voltages V _{on are} sequentially applied to all the gate lines G ₁ -G _n during one frame to apply data voltages to all the pixels. At the end of one frame, the next frame starts and the state of the inversion signal RVS applied to the data driver 500 is controlled so that the polarity of the data voltage applied to each pixel is opposite to that of the previous frame ("frame inversion). "). In this case, the polarity of the data voltage flowing through one data line may be changed (“line inversion”) within one frame or the polarity of the data voltage applied to one pixel row may be different according to the characteristics of the inversion signal RVS ( "Dot reversal").

Next, the video signal correction in the gray signal modifier included in the signal controller 600 according to the exemplary embodiment of the present invention will be described in detail.

The image signal correction in the image signal correcting unit according to the embodiment of the present invention improves the response speed of the liquid crystal and prevents a screen defect including a flicker phenomenon from the image signal of the previous frame (hereinafter referred to as "previous image signal"). The corrected video signal is generated based on the video signal of the current frame (hereinafter referred to as "current video signal") and the video signal of the next frame (hereinafter referred to as "next video signal").

In an exemplary embodiment of the present invention, the previous video signal, the current video signal, and the next video signal are compared, and the previous video signal, the current video signal, and the next video signal are classified into at least two cases according to the comparison result. Then, according to the classification, the correction variables required for the operation are first determined by using the previous video signal, the current video signal, and the next video signal, and then the values of the previous video signal, the current video signal, the next video signal, and the determined correction variables are determined. The corrected video signal is calculated.

For convenience of description, the video signal G _n-1 of the (n-1) th frame is called the previous video signal, the video signal G _n of the nth frame is called the current video signal, and (n + 1 The video signal G _{n + 1} of the) th frame is defined as a next video signal.

First, before the video signal correction according to the embodiment of the present invention, the first correction signal g ₁ ′ based on the current video signal G _n and the next video signal G _{n + 1} using interpolation. ) Will be described.

For convenience, it is assumed that the video signal is 8 bits, the upper bit MSB is x bits, and the lower bit LSB is y bits.

In the embodiment of the present invention, since the video signal is 8 bits, the number of gray levels that can be represented is 2 ⁸ = 256. Since the number of gray levels is 256, the combination of the current video signal G _n and the current video signal G _{n + 1} is 256 × 256 = 65,536.

Determining the corrected video signal separately for each of such a large number of combinations and generating the corrected video signal accordingly is time- and space-intensive, so it is divided into appropriate bundles.

In the present exemplary embodiment, the corrected video signal is divided according to each zone by dividing the blocks based on the values of the upper bits MSB x bits of the current video signal G _n and the next video signal G _{n + 1} . Create On the other hand, since the upper bit of the video signal is x bits, the entire area is divided into a width x length = 2 ^x 2 ^x areas.

A basic correction signal is determined for the vertices defining the zones, that is, the points where the lower bits LSB of the current and next video signals G _n , G _{n + 1} are all zero. This basic correction signal is predetermined by experiment or the like. Interpolation is applied to the remaining points except for the vertex to calculate the first correction signal g ₁ ′. When interpolation is applied to a point in an area, the interpolation method is applied based on the basic correction signal of the four vertices defining the area.

The reason why the interpolation method is applied to four points in each zone is that the basic correction signal is discontinuous near the boundary of the zone when it is interpolated based on two or three points, for example. Interpolation based on the four points that determine the zone, as in this example, eliminates discontinuities near the zone boundary.

On the other hand, the correction variables for each zone, that is, the variables required for applying the predetermined basic correction signal and interpolation method, are stored in a lookup table. The correction variable is read from the lookup table to calculate a first correction signal g ₁ ′ through an appropriate interpolation function.

Calculating the second correction signal g ₂ ′ based on the previous image signal G _n-1 and the current image signal G _n is the same as calculating the first correction signal g ₁ ′. Calculate. Of course, the difference between using a lookup table for calculating the first correction signal g ₁ ′ and a different lookup table, that is, using different correction variables is different.

Next, image signal correction according to an embodiment of the present invention will be described.

First, in one embodiment of the present invention, three cases are classified.

In the first case, the difference between the previous video signal G _n-1 and the current video signal G _n is less than or equal to the set value α, and the difference between the current video signal G _n and the next video signal G _{n + 1} . This is the case when the difference exceeds the other set value β.

The second case is a case where the difference between the previous video signal G _n-1 and the current video signal G _n exceeds the set value α.

In the third case, the difference between the previous video signal G _n-1 and the current video signal G _n is less than or equal to the set value α, and the difference between the current video signal G _n and the next video signal G _{n + 1} . This is the case when the difference is equal to or less than another set value β.

If you write in each case

First case: | G _n-1 -G _n | ≤α, | G _n -G _{n + 1} |> β,

Second case: | G _n-1 -G _n |> α,

Third case: | G _n-1 -G _n | ≤α, | G _n -G _{n + 1} | ≤β

to be.

The setting values α and β are values that are predetermined according to the characteristics of the liquid crystal display device. If the set values α and β are both “0”, each case is as follows.

First case: G _n-1 = G _n ≠ G _{n + 1} ,

Second case: G _n-1 ≠ G _n ,

Third case: G _n-1 = G _n = G _{n + 1}

In this embodiment, for each case, the current video signal G _n is corrected in the following manner.

In the first case, the gradation change from the previous frame to the current frame is small but the gradation change from the current frame to the next frame is large. In this case, the current video signal G _n and the next video signal G _{n + 1} Is corrected based on the current video signal G _n . More specifically, in order to prepare for a large gradation change from the current frame to the next frame, a predetermined portion of the gradation difference between the current frame and the next frame is referred to by referring to the next image signal G _{n + 1} in advance in the current frame. The current video signal G _n is corrected by reflecting the current frame in advance. In this case, the corrected current image signal G _n ′ is the same as the first correction signal g ₁ ′ described above. As such, when the pre-shoot operation is performed in the current frame, the target luminance corresponding to the next image signal G _{n + 1} can be quickly approached in the next frame, and the target luminance can be stably maintained without changing the luminance even after the approach. Is maintained.

The second case is a case where the variation of the gradation from the previous frame to the current frame is large, and in this case, the current video signal G based on the previous video signal G _n-1 and the current video signal G _n . _n ) is corrected. That is, in this case, the current image signal G _n is corrected regardless of the next image signal G _{n + 1} , and the corrected current image signal G _n ′ is the second correction signal g ₂ ′ described above. Same as

The third case is a case where the gradation fluctuation of three consecutive frames is small, and in this case, the current video signal G _n is not corrected. Even if the gradation is slightly different, the image is more likely to be caused by noise rather than actually changing, so that the amount of change in gradation is reduced by leaving it without correction rather than promptly responding to the gradation change.

Next, in another embodiment of the present invention, five cases are classified.

In the first case, the difference between the previous video signal G _n-1 and the current video signal G _n is less than or equal to the set value α, and the next video signal G _{n + 1} is the current video signal G _{n + 1.} Greater than).

In the second case, the previous video signal G _n-1 is greater than the sum of the current video signal G _n and the set value α, and the current video signal G _n and the next video signal G _{n + 1} are separated from each other. The difference is larger than the set value β.

In a third case, the previous video signal G _n-1 is greater than the sum of the current video signal G _n and the set value α, and the current video signal G _n and the next video signal G _{n + 1} are separated from each other. This is the case when the difference is less than or equal to the set value β.

The fourth case is a case where the current video signal G _n is larger than the sum of the previous video signal G _n-1 and the set value α.

In a fifth case, the difference between the previous video signal G _n-1 and the current video signal G _n is less than or equal to the set value α, and the current video signal G _n is greater than or equal to the next video signal G _{n + 1} . If it is.

If you write in each case

First case: | G _n-1 -G _n | ≤α, G _{n + 1} > G _n ,

Second case: G _n-1 -G _n > α, | G _n -G _{n + 1} |> β

Third case: G _n-1 -G _n > α, | G _n -G _{n + 1} | ≤β

Fourth case: G _n -G _n-1 > α

Fifth case: | G _n-1 -G _n | ≤α, G _{n + 1} <G _n

to be. Herein, the setting values α and β are predetermined values according to the characteristics of the liquid crystal display device as in the previous embodiment.

In this embodiment, for each case, the current video signal G _n is corrected in the following manner.

In the first case, the gradation change from the previous frame to the current frame is small but the gradation change from the current frame to the next frame is high. In this case, the previous video signal G _n-1 and the current video signal G _n ) And the current video signal G _n based on the next video signal G _{n + 1} . The corrected current image signal G _n ′ has a maximum value among the first correction signal g ₁ ′, the second correction signal g ₂ ′, and the current image signal G _n . In this way, not only the first correction signal g ₁ ′ but also the second correction signal g ₂ ′ and the current image signal G _n are referred to to correct the current image signal G _n to perform a reliable preshooting operation. Can be.

In the second case, the gray level of the current frame drops sharply with respect to the gray level of the previous frame, and the gray level of the next frame is greatly changed. In this case, the previous image signal G _n-1 and the current image signal G _n are different. The current video signal G _n is corrected on the basis of the correction. The corrected current image signal G _n ′ has a smaller value between the second correction signal g ₂ ′ and the current image signal G _n . As such, by correcting the current video signal to a lower signal, excessive overshoot in the next frame can be prevented.

Claim a case 3 case where the gray level of the current frame sharply tteoleojina present the gray level of the next frame small variation with respect to the gray level of the frame with respect to the gray level of the previous frame, in which case the previous image signal (G _n-1) and the current image signal is the same as (G _n) by the current image signal (G _n) it is the image signal (G _n ') the corrected contrast to the second case, but the correction is a second correction signal (g _2') based on a.

The fourth case is a case in which the gray level of the current frame increases rapidly with respect to the gray level of the previous frame. In this case, the current video signal G _n is based on the previous video signal G _n-1 and the current video signal G _n. ) Is corrected, but the corrected current image signal G _n ′ is equal to the second correction signal g ₂ ′ as in the third case.

The fifth case is a case where the gradation change from the previous frame to the current frame is small and the gradation change from the current frame to the next frame is low, in which case the current video signal G _n is not corrected.

Next, an image signal correction unit according to an embodiment of the present invention for implementing such image signal correction will be described in detail with reference to FIG. 7.

7 is a block diagram of an image signal corrector according to an exemplary embodiment of the present invention.

As shown in FIG. 7, the image signal corrector 650 according to the present embodiment includes a signal receiver 61, a frame memory 62 connected to the signal receiver 61, and a signal. And a gray signal converter 64 coupled to the receiver 61 and the frame memory 62.

The video signal converter 64 has a lookup table 640 connected to the signal receiver 61 and the frame memory 62, and whose input is a lookup table 640, the signal receiver 61 and the frame memory 62. A calculator 643, and an input is connected to the signal receiver 61 and the frame memory 62, and the output is a lookup table 640. And a signal comparator 644 connected to the calculator 643.

The signal receiver 61 of the image signal corrector 650 illustrated in FIG. 7 may receive the image signal G _{m + 1} from a signal source (not shown), and may process the image signal corrector 650. Convert to video signal. The signal receiver 61 supplies this video signal to the frame memory 62 and the video signal converter 64 as the next video signal G _{n + 1} .

The frame memory 62 supplies the stored previous video signal G _n-1 and the current video signal G _n to the video signal converter 64, and transmits the next video signal G transmitted from the signal receiver 61. _{n + 1} ).

Then the video signal from the video signal converter 64, the signal comparison unit 644, a frame memory 62 prior to the image signal (G _n-1) and the current image signal (G _n) and the signal receiver (61) from the ( The cases are classified based on G _{n + 1} ), and a signal corresponding to each case is generated and supplied to the lookup table 640 and the calculator 643.

A look-up table in the video signal converter 64, 640 is divided into areas of two 2 ^x 2 × ^x. In one zone, the first correction variable f ₁ based on the current video signal G _n and the next video signal G _{n + 1} is stored, and in the other zone the previous video signal G _n-1 and The second correction variable f ₂ based on the current video signal G _n is stored. The first correction variable f ₁ is a variable necessary for applying the first basic correction signal and interpolation when the lower bits of the current image signal G _n and the next image signal G _{n + 1} are both zero. And the second correction variable f ₂ is required to apply the second basic correction signal and the interpolation method when the lower bits of the previous image signal G _n-1 and the current image signal G _n are both zero. It consists of variables.

The lookup table 640 extracts the value of the first correction variable f ₁ or the second correction variable f ₂ according to the signal from the signal comparing unit 644 and outputs the value to the calculator 643.

On the other hand, the calculator 643 determines a case according to the signal from the signal comparator 644, and the first correction variable f ₁ or the second correction variable f ₂ from the lookup table 640 and the previous image signal. After calculating the first and second correction signals g ₁ ′ and g ₂ ′ using (G _n-1 ), the current image signal G _n , or the next image signal G _{n + 1} , the correction is performed. Generates a video signal G _n '.

Next, an image signal correcting unit according to another exemplary embodiment of the present invention will be described with reference to FIG. 8.

8 is a block diagram of an image signal corrector according to another exemplary embodiment of the present invention. In FIG. 8, overlapping parts are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 8, the frame memory 62 of the image signal correcting unit 650 according to the present embodiment includes a first frame memory 621 and a first frame memory 621 connected to the signal receiver 61. The lookup table 640 of the image signal converter 64 is connected to the signal receiver 61 and the first frame memory 621. 641 and a second lookup table 642 connected to the first and second frame memories 621 and 622.

The first frame memory 621 supplies the stored current video signal G _n to the video signal converter 64 and the second frame memory 622, and transmits the next video signal G transmitted from the signal receiver 61. _{n + 1} ).

The second frame memory 622 supplies the stored previous video signal G _n-1 to the video signal converter 64 and stores the current video signal G _n from the first frame memory 621. .

The first lookup table 641 stores the first correction variable f ₁ based on the current image signal G _n and the next image signal G _{n + 1} , and the previous image signal in the second lookup table 642. The second correction variable f ₂ based on (G _n-1 ) and the current video signal G _n is stored. The first and second lookup tables 641 and 642 receive a signal corresponding to each case from the signal comparator 644, and the previous image signal G _n-1 , the current image signal G _n , and the next image signal ( The first or second correction variables f ₁ and f ₂ corresponding to G _{n + 1} ) are sent to the calculator 643.

Next, an image signal correcting unit according to another exemplary embodiment of the present invention will be described with reference to FIG. 9.

9 is a block diagram of an image signal correcting unit according to still another exemplary embodiment of the present invention. Parts overlapped with those of FIG. 7 are given the same reference numerals, and description thereof will be omitted.

As shown in FIG. 9, the frame memory 62 of the image signal correcting unit 650 according to the present embodiment includes a first frame memory 621 and a first frame memory 622 connected to the signal receiver 61. A second frame memory 622 connected to the second frame memory 622, and a third frame memory 623 connected to the second frame memory 623.

The first frame memory 621 supplies the next stored video signal G _{n + 1} to the second frame memory 622 and the video signal converter 64, and (n + 2) from the signal receiver 61. The first frame video signal G _{n + 2} is received and stored.

The second frame memory 622 supplies the stored current video signal G _n to the third frame memory 623 and the video signal converter 64, and the next video signal G from the first frame memory 621. _{n + 1} ) and remember.

The third frame memory 623 supplies the previous video signal G _n-1 stored therein to the video signal converter 64 and receives and stores the current video signal G _n from the second frame memory 622. .

As shown in FIG. 9, the image signal converter 64 includes one lookup table 640, but may include two lookup tables as in the previous embodiment.

Although the image signal corrector 650 or the image signal converter 64 according to an exemplary embodiment of the present invention is expressed as being part of the signal controller 600, the image signal corrector 650 or the image signal converter 64 may exist separately from the signal controller 600.

10, the operation of the video signal converter 64 according to an embodiment of the present invention will be described in detail.

10 is a flowchart illustrating an operation of a video signal converter according to an embodiment of the present invention.

First, when the operation is started (S10), the video signal converter 64, and then the image from the previous image signal (G _n-1) and the current image signal (G _n) from the frame memory 62, the signal receiver 61 The signal G _{n + 1} is read (S20).

Then, the signal comparator 644 calculates a difference between the previous video signal G _n-1 and the current video signal G _n , and compares the result with the set value α (S30).

In this case, the set value α may vary according to the state or environment of the video signal. Generally, when the video signal is affected by noise, the α value is set to a large value. Otherwise, the α value is set to a small value. Select with. The value of alpha is preferably a number between 0 and 16 divided by the total number of grays divided by 16, for example, when the number of grays is 256.

As a result of comparing the difference between the previous video signal G _n-1 and the current video signal G _n with the set value α, if the difference is less than or equal to the set value α, the signal comparator 644 may determine the current video signal. The difference between (G _n ) and the next video signal (G _{n + 1} ) is calculated and then compared with the set value (β) (S40).

At this time, the set value β can also be selected in the same manner as the set value α.

As a result of comparing the difference between the current video signal G _n and the next video signal G _{n + 1} with the set value β, if the difference is less than or equal to the set value β, the signal comparator 644 corresponds to this. The signal is output to the calculator 643.

Accordingly, the calculator 643 outputs the current video signal G _n as a corrected video signal G _n ′ without performing a separate correction operation (S50).

However, if the difference between the current video signal G _n and the next video signal G _{n + 1} is greater than the set value β in step S40, the signal comparator 644 may look up the corresponding signal to the lookup table. 640 and arithmetic operator 643.

Accordingly, the calculator 643 reads the first correction variable f ₁ from the lookup table 640 (S60). Then, the first correction signal g ₁ ′ is calculated using the read first correction variable f ₁ , the current image signal G _n , and the next image signal G _{n + 1} (S70).

In this case, the corrected image signal G _n ′ may be expressed as a function as follows. Where function F ₁ is an interpolation function based on the variables f ₁ , G _n , and G _{n + 1} .

G _n '= g ₁ ' = F ₁ (f ₁ , G _n , G _{n + 1} )

On the other hand, if the difference between the previous video signal G _n-1 and the current video signal G _n is greater than the set value α in operation S30, the signal comparator 644 may look up a corresponding signal to the lookup table. 640 and arithmetic operator 643.

Accordingly, the calculator 643 reads the second correction variable f ₂ from the lookup table 640 (S80). Thereafter, a second correction signal g ₂ ′ is calculated using the read second correction variable f ₂ , the previous image signal G _n-1 , and the current image signal G _n (S90).

In this case, the corrected image signal G _n ′ may be expressed as a function as follows. Where function F ₂ is an interpolation function depending on the variables f ₂ , G _n-1 , and G _n .

G _n '= g ₂ ' = F ₂ (f ₂ , G _n-1 , G _n )

In this manner, the image signal converter 64 uses the corresponding interpolation function according to the case of the input image signals G _{n + 1} , G _n , and G _n-1 to compensate for the image signals G _n ′. Calculate and output

11, the operation of the video signal converter 64 according to another embodiment of the present invention will be described in detail.

11 is a flowchart illustrating an operation of a video signal converter according to another embodiment of the present invention.

First, a video signal converter 64 is the next video signal (G _{n + 1)} from the previous image signal (G _n-1) and the current image signal a (G _n), the signal receiver 61 from the frame memory 62 It reads (S120).

Thereafter, the signal comparator 644 calculates a difference between the previous video signal G _n-1 and the current video signal G _n and then compares the set value α with each other (S130). As a result of the comparison in step S130, if the difference is less than or equal to the set value α, the signal comparison unit 644 compares the current video signal G _n with the next video signal G _{n + 1} (S135). As a result of the comparison in operation S135, when the next video signal G _{n + 1} is greater than the current video signal G _n , the signal comparator 644 sends the corresponding signal to the lookup table 640 and the calculator 643. Output

Accordingly, the calculator 643 reads the first and second correction variables f ₁ and f ₂ from the lookup table 640 (S140). Thereafter, a first correction signal g ₁ ′ is calculated using the first correction variable f ₁ , the current image signal G _n , and the next image signal G _{n + 1} , and the second correction variable f is calculated. ₂ ) the second correction signal g ₂ ′ is calculated using the previous image signal G _n-1 and the current image signal G _n (S143). The calculator 643 then selects the largest value among the first and second correction signals g ₁ ′ and g ₂ ′ and the current image signal G _n and outputs the largest value as the corrected image signal G _n ′ (S145). ).

On the other hand, in step (S135), and then image signals (G _{n + 1),} the unit 644 compares equal to or less than the current image signal (G _n) signal from and outputs the signal corresponding to the arithmetic unit 643, whereby the operator ( 643 outputs the current video signal G _n as a corrected video signal G _n ′ without performing a separate correction operation (S150).

If the difference between the previous video signal G _n-1 and the current video signal G _n is greater than the set value α in step S130, the signal comparator 644 may convert the previous video signal G _n-1 . In operation S160, a value obtained by subtracting the current video signal G _n is compared with a set value α. As a result of the comparison in step S160, if the subtracted value is larger than the set value α, the difference between the current video signal G _n and the next video signal G _{n + 1} is calculated, and then the set value β Compare (S165). As a result of the comparison in step S165, if the difference is greater than the set value β, the signal comparator 644 outputs the corresponding signal to the lookup table 640 and the calculator 643.

Accordingly, the calculator 643 reads the second correction variable f ₂ from the lookup table 640 (S170). Thereafter, a second correction signal g ₂ ′ is calculated using the second correction variable f ₂ , the previous image signal G _n-1 , and the current image signal G _n (S173). Then, the calculator 643 selects a small value from the second correction signal g ₂ ′ and the current image signal G _n and outputs the small value as the corrected image signal G _n ′ (S175).

If the difference is less than or equal to the set value β in step S165 or the subtracted value is less than or equal to the set value α in step S160, the signal comparator 644 looks up a signal corresponding thereto. Output to table 640 and operator 643.

Accordingly, the calculator 643 reads the second correction variable f ₂ from the lookup table 640 (S180). Thereafter, a second correction signal g ₂ ′ is calculated using the second correction variable f ₂ , the previous image signal G _n-1 , and the current image signal G _n (S183). G _n ') is output (S185).

Next, the result of applying the corrected image signal generated according to the exemplary embodiment of the present invention to the test screen of FIG. 2 will be described.

12 is a waveform diagram illustrating a luminance response to a corrected image signal in the liquid crystal display according to the exemplary embodiment of the present invention.

Referring to FIG. 12 in comparison with FIG. 3, it can be seen that the overshoot is significantly reduced in the fourth frame, and the target luminance is approached within one frame in terms of response speed. In addition, it can be seen that the frames after the fourth frame have almost constant luminance without deterioration of the luminance. As a result, the cyan tail as shown in FIG. 2 is not visible.

In addition, the wire frame flicker phenomenon is also solved by appropriately determining the first and second correction variables f ₁ and f ₂ , and the problem of lowering the luminance in the low gradation region is also improved.

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.

As described above, in the liquid crystal display according to the present invention, the cases are classified according to the characteristics of the difference between the previous video signal, the current video signal, and the next video signal, and corrected in different ways according to each case. The corrective operation is performed to improve response speed while preventing defects in the LCD screen, such as flicker.

1 is a waveform diagram showing a luminance response to an image signal corrected by a DCC method.

2 is a diagram illustrating a test screen of a liquid crystal display.

FIG. 3 is a waveform diagram illustrating a luminance response of an image signal corrected by the DCC method when displayed as in the test screen of FIG. 2.

4A shows the relationship between the liquid crystal capacitance and the pixel voltage in the case of maintaining "128" gray scale.

4B shows the relationship between the liquid crystal capacitance and the pixel voltage when the pixel voltage corresponding to the "0" gray scale is applied.

4C shows the relationship between the liquid crystal capacitance and the pixel voltage at the end of one frame.

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

6 is an equivalent circuit diagram of one pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

7 is a block diagram of an image signal corrector according to an exemplary embodiment of the present invention.

8 is a block diagram of an image signal corrector according to another exemplary embodiment of the present invention.

9 is a block diagram of an image signal corrector according to another exemplary embodiment of the present invention.

10 is a flowchart illustrating an operation of a video signal converter according to an embodiment of the present invention.

11 is a flowchart illustrating an operation of a video signal converter according to another embodiment of the present invention.

12 is a waveform diagram illustrating a luminance response to a corrected image signal in the liquid crystal display according to the exemplary embodiment of the present invention.

Claims (38)

A plurality of pixels, An image signal correction unit for comparing the previous image signal, the current image signal, and the next image signal supplied from a signal source and correcting the current image signal according to a comparison result; A data driver converting the corrected image signal from the image signal corrector into a corresponding data voltage and supplying the pixel to the pixel; Liquid crystal display comprising a. In claim 1, If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value, and the difference between the current video signal and the next video signal exceeds a second set value, based on the current video signal and the next video signal. And correcting the current video signal. In claim 2, And correcting the current video signal based on the previous video signal and the current video signal when a difference between the previous video signal and the current video signal exceeds the first set value. The method of claim 2 or 3, If the difference between the previous video signal and the current video signal is less than or equal to the first set value, and the difference between the current video signal and the next video signal is less than or equal to the second set value, the liquid crystal display does not correct the current video signal. Device. In claim 1, If the previous video signal is the same as the current video signal and the current video signal is different from the next video signal, the current video signal is corrected based on the current video signal and the next video signal. If the previous video signal is different from the current video signal, the current video signal is corrected based on the previous video signal and the current video signal. If the previous video signal and the current video signal and the next video signal are the same, the current video signal is not corrected. Liquid crystal display. In claim 1, If the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than a second set value, based on the previous video signal and the current video signal. And a first corrected video signal generated by correcting the current video signal. In claim 6, And the first corrected image signal has a smaller value among an interpolated value and the current image signal according to the previous image signal and the current image signal. In claim 6, If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the previous video signal and the current video signal and the next video signal are based on the previous video signal. A liquid crystal display for generating a second corrected video signal by correcting a current video signal. In claim 8, The second corrected image signal has a value interpolated according to the previous image signal and the current image signal, a value interpolated according to the current image signal and the next image signal, and a maximum value among the current image signal. . In claim 6 or 8, The previous video signal is greater than the sum of the current video signal and the first setting value and the difference between the current video signal and the next video signal is equal to or less than the second setting value; If the current video signal is greater than the sum of the previous video signal and the first set value, And a third corrected video signal corrected from the current video signal based on the previous video signal and the current video signal. In claim 10, And the third corrected image signal is a value interpolated according to the previous image signal and the current image signal. In claim 6 or 8, And not correcting the current video signal when a difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the current video signal is greater than or equal to the next video signal. In claim 1, The image signal correction unit, A frame memory which outputs the stored previous video signal and the current video signal and stores the next video signal; and A look-up table for outputting a value of a corresponding correction parameter according to the next video signal, the previous video signal from the frame memory, and the current video signal Liquid crystal display comprising a. In claim 13, The frame memory includes a first frame memory and a second frame memory, The first frame memory outputs the current video signal and stores the next video signal, The second frame memory outputs the previous video signal and stores the current video signal from the first frame memory. Liquid crystal display. In claim 13, The frame memory includes three frame memories, and the three frame memories respectively store the previous image signal, the current image signal, and the next image signal. The method according to any one of claims 13 to 15, And the lookup table stores a first correction variable predetermined according to the current video signal and the next video signal, and a second correction variable predetermined according to the previous video signal and the current video signal. The method of claim 16, The lookup table, Outputting the first correction variable when a difference between the previous video signal and the current video signal is equal to or less than a first preset value and a difference between the current video signal and the next video signal exceeds a second preset value; Outputting the second correction parameter when a difference between the previous video signal and the current video signal exceeds the first set value; Liquid crystal display. The method of claim 16, The lookup table, Outputting the first and second correction variables when a difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the next video signal is larger than the current video signal; Outputting the second correction parameter when a difference between the previous video signal and the current video signal is greater than a first set value; Liquid crystal display. The method of claim 16, The lookup table includes first and second lookup tables, The first lookup table stores the first correction parameter, The second lookup table stores the second correction variable. Liquid crystal display. The method according to any one of claims 13 to 15, The lookup table includes first and second lookup tables, The first lookup table outputs a first correction variable which is predetermined according to the next video signal and the current video signal and stored in the first lookup table. The second lookup table is configured according to the current video signal and the next video signal to output a second correction variable stored in the second lookup table. Liquid crystal display. The method according to any one of claims 13 to 15, The image signal correction unit, A signal comparator for comparing the next video signal with the previous video signal from the frame memory and the current video signal to generate a corresponding signal according to the comparison result; and The corrected video signal is calculated by calculating the correction variable from the lookup table, the next video signal, the previous video signal from the frame memory, and the current video signal in a manner determined according to a signal from the signal comparator. Arithmetic operators Liquid crystal display further comprising. The method of claim 21, The lookup table stores a first correction variable predetermined according to the current video signal and the next video signal, and a second correction variable predetermined according to the previous video signal and the current video signal. The calculator, If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value and the difference between the current video signal and the next video signal exceeds a second set value, the first correction variable, the current video signal, and Calculate with the next video signal, If the difference between the previous video signal and the current video signal exceeds the first set value, the operation is performed with the second correction variable, the previous video signal and the current video signal, If the difference between the previous video signal and the current video signal is less than or equal to the first setting value and the difference between the current video signal and the next video signal is less than or equal to the second setting value, the current video signal is not corrected. Liquid crystal display. The method of claim 21, The lookup table stores a first correction variable predetermined according to the current video signal and the next video signal, and a second correction variable predetermined according to the previous video signal and the current video signal. The calculator, If the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than a second set value, the second correction parameter, the previous video signal and the Operate on the current video signal, If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the first and second correction variables, the current video signal, and the next video signal. Compute with The previous video signal is greater than the sum of the current video signal and the first preset value, and the difference between the current video signal and the next video signal is equal to or less than the second preset value, or the current video signal is equal to the previous video signal. When the sum is greater than the sum of the first set value, the second correction variable is calculated based on the previous image signal and the current image signal. If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value and the current video signal is greater than or equal to the next video signal, the current video signal is not corrected. Liquid crystal display. Receiving a previous video signal, a current video signal, and a next video signal, Comparing the previous video signal with the current video signal and the next video signal, and Correcting the current video signal according to a comparison result in the comparing step Image signal correction method of a liquid crystal display comprising a. The method of claim 24, The comparing step, Comparing a difference between the previous video signal and the current video signal and a first set value; and Comparing a difference between the current video signal and the next video signal and a second preset value; Image signal correction method of a liquid crystal display comprising a. The method of claim 25, If the difference between the previous video signal and the current video signal is less than or equal to the first setting value and the difference between the current video signal and the next video signal exceeds the second setting value, the current video signal and the next video signal. And correcting the current video signal based on the image signal correction method of the liquid crystal display. The method of claim 25 or 26, And correcting the current video signal based on the previous video signal and the current video signal when a difference between the previous video signal and the current video signal exceeds the first set value. The method of claim 25 or 26, If the difference between the previous video signal and the current video signal is less than or equal to the first set value, and the difference between the current video signal and the next video signal is less than or equal to the second set value, the liquid crystal display does not correct the current video signal. How to calibrate the video signal of the device. The method of claim 28, And correcting the current video signal based on the previous video signal and the current video signal when a difference between the previous video signal and the current video signal exceeds the first set value. The method of claim 25, The correction step, Reading a first correction parameter predetermined according to the current video signal and the next video signal, Reading a second correction parameter predetermined according to the previous video signal and the current video signal Image signal correction method of a liquid crystal display comprising a. The method of claim 30, If the difference between the previous video signal and the current video signal is less than or equal to the first set value, and the difference between the current video signal and the next video signal exceeds the second set value, the first correction parameter and the current video. Correct the current video signal based on a signal and the next video signal, If the difference between the previous video signal and the current video signal exceeds the first set value, the current video signal is corrected based on the second correction variable, the previous video signal and the current video signal, If the difference between the previous video signal and the current video signal is less than or equal to the first setting value and the difference between the current video signal and the next video signal is less than or equal to the second setting value, the current video signal is not corrected. Image signal correction method of liquid crystal display device. The method of claim 25, The comparing step, Comparing the sum of the current video signal and the first set value with the previous video signal, and Comparing the next video signal with the current video signal The image signal correction method of the liquid crystal display further comprising. 33. The method of claim 32, If the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than the second set value, the previous video signal and the current video signal And correcting the current video signal based on the interpolated value according to the previous video signal, the current video signal, and the smaller of the current video signal. The method of claim 32 or 33, If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the previous video signal and the current video signal and the next video signal are based on the previous video signal. A liquid crystal display for correcting a current video signal, and correcting the interpolated value according to the previous video signal and the current video signal, the interpolated value according to the current video signal and the next video signal, and the maximum value of the current video signal. How to calibrate the video signal of the device. The method of claim 34, The previous video signal is greater than the sum of the current video signal and the first preset value, and the difference between the current video signal and the next video signal is equal to or less than the second preset value, or the current video signal is equal to the previous video signal. If greater than the sum of the first set value, the image of the liquid crystal display device to correct the current video signal based on the previous video signal and the current video signal, but to the interpolated value according to the previous video signal and the current video signal. Signal correction method. 36. The method of claim 35 wherein And not correcting the current video signal when a difference between the previous video signal and the current video signal is equal to or less than a first predetermined value and the current video signal is greater than or equal to the next video signal. 33. The method of claim 32, The correction step, Reading a first correction parameter predetermined according to the current video signal and the next video signal, Reading a second correction parameter predetermined according to the previous video signal and the current video signal Image signal correction method of a liquid crystal display comprising a. The method of claim 37, When the previous video signal is greater than the sum of the current video signal and the first set value, and the difference between the current video signal and the next video signal is greater than a second set value, the second correction parameter and the previous video signal are compared. Calculate with the current video signal, If the difference between the previous video signal and the current video signal is less than or equal to the first set value and the next video signal is greater than the current video signal, the first and second correction variables, the current video signal, and the next video signal. Compute with The previous video signal is greater than the sum of the current video signal and the first preset value, and the difference between the current video signal and the next video signal is equal to or less than the second preset value, or the current video signal is equal to the previous video signal. When the sum is greater than the sum of the first set value, the second correction variable is calculated based on the previous image signal and the current image signal. If the difference between the previous video signal and the current video signal is less than or equal to a first predetermined value and the current video signal is greater than or equal to the next video signal, the current video signal is not corrected. Image signal correction method of liquid crystal display device.