KR101463035B1 - Liquid crystal display and method for driving the same - Google Patents

Abstract

A liquid crystal display device includes a liquid crystal display panel for displaying an image, a gate driver for applying a gate signal to the liquid crystal display panel, a data driver for applying a data signal to the liquid crystal display panel, Wherein the signal control unit includes a control signal generation unit for increasing a frame rate by a multiple and a plurality of correction data sets having different correction characteristics for a frame expanded in multiple, And a method of driving the liquid crystal display device.

As described above, the present invention corrects image data of a frame by increasing the frame rate to a multiple and alternately using a plurality of correction data sets having different correction characteristics for each position of a user in a multi-frame. Accordingly, a screen of a multiple of the input is displayed on the liquid crystal display panel. Since the user recognizes the average image characteristic of a plurality of screens providing optimized image characteristics at various positions, The problem can be solved.

Color distortion, visibility, viewing angle, frame rate, liquid crystal display device.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly, to a liquid crystal display device and a driving method thereof that can provide uniform visibility irrespective of a user's position.

A liquid crystal display (Liquid Crystal Display) is a display device that implements an image by controlling the amount of light transmitted from a light source by using the optical anisotropy of the liquid crystal molecules and the polarization characteristics of the polarizer, and can realize a lightweight thin, high resolution, And the power consumption is low, and the application range thereof is rapidly expanding recently.

Such a liquid crystal display device has a problem that a viewing angle is relatively narrow as compared with other display devices because light is transmitted only through a light transmission axis of liquid crystal molecules to realize an image. In the PVA (Patterned Vertically Aligned) method, the liquid crystal molecules are vertically aligned with respect to the upper and lower substrates, and the pixel electrode and the common electrode, which is an opposite electrode thereof, A pattern or a projection pattern is formed, thereby distorting the electric field formed between the two electrodes to form a plurality of domains, thereby improving the viewing angle.

Recently developed SPVA (Super Patterned Vertically Aligned) method has a main pixel and a sub pixel having different voltages in a unit pixel, and the light transmission axis of the liquid crystal molecule changes Thereby further improving the viewing angle.

With the development of various technologies, the viewing angle problem of the liquid crystal display device has been improved to some extent, so that the visibility problem, especially the side viewability problem, has been raised as an important factor for determining the display quality of the liquid crystal display device. That is, due to the fundamental viewing angle problem of the liquid crystal display device, the image displayed on the screen has fine color deformation on the upper, lower, right, and left sides based on the user. However, since the degree of color deformation varies depending on the position of the user, Image quality, that is, visibility is changed. For example, depending on the user's position, the viewing angles for viewing the right and left screens of the liquid crystal display device are different. However, due to differences in color deformation, the image characteristics of the right and left screens are different, The visibility of the user viewing the screen is changed. This visibility problem is more severe in the left and right screens than in the upper and lower screens, and becomes more severe as the liquid crystal display becomes larger.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an image processing apparatus and a method thereof, which can increase a frame rate of an image signal by a multiple and correct a plurality of correction data sets ) And correcting the image data (R ', G', B ') of the frame by alternately using the image data of the frame to provide uniform visibility irrespective of the position of the user, and a method of driving the same It has its purpose.

According to one aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal display panel for displaying an image, a gate driver for applying a gate signal to the liquid crystal display panel, And a signal controller for controlling the gate driver and the data driver, wherein the signal controller comprises: a control signal generator for increasing a frame rate by a multiple, a plurality of control signals generating a plurality of And an image signal processing section for correcting the image data of the frame by alternately using the correction data sets.

The present invention further includes a memory unit in which the plurality of correction data sets are stored.

It is preferable that the plurality of correction data sets have different correction characteristics for each position of the user.

Wherein the plurality of correction data sets include a first lookup table composed of correction data for providing an optimal image to the left user based on the center of the screen and a second lookup table configured of correction data for providing an optimal image to the right user do. At this time, the correction data preferably includes at least one of data for ACC correction, data for DCC correction, and data for gamma correction.

The first and second lookup tables are alternately selected by a selection signal and provided to the image signal processing unit. At this time, the selection signal is preferably generated based on the vertical synchronization start signal generated by the control signal generation unit.

The image signal processing section preferably includes at least one of an ACC circuit, a DCC circuit, and a gamma compensation circuit.

It is preferable that the control signal generator increases the frame rate of 60 Hz to 120 Hz.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display, including: increasing a frame rate to a multiple to increase a frame to a multiple; And a step of displaying the image by applying the corrected image data to the liquid crystal display panel.

It is preferable that the plurality of correction data sets have different correction characteristics for each position of the user.

Wherein the plurality of correction data sets includes a first lookup table composed of correction data for providing an optimal image to the left user based on the center of the screen and a second lookup table composed of correction data for providing an optimal image to the right user .

The correction step preferably corrects the image data using the first lookup table in the Nth frame and corrects the image data in the (N + 1) th frame using the second lookup table.

It is preferable that the image data is corrected by at least one of an ACC method, a DCC method, and a gamma compensation method.

The present invention preferably raises the frame rate from 60 Hz to 120 Hz.

The present invention corrects image data of a corresponding frame by increasing a frame rate to a multiple and alternately using a plurality of correction data sets having different correction characteristics for each position of a user in a multi-frame. Accordingly, a screen of a multiple of the input is displayed on the liquid crystal display panel. Since the user recognizes the average image characteristic of a plurality of screens providing optimized image characteristics at various positions, The problem can be solved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, it will be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, Is provided to fully inform the user. Like reference numerals refer to like elements throughout.

FIG. 1 is a block diagram schematically showing a liquid crystal display according to an embodiment of the present invention, and FIG. 2 is a detailed block diagram of a signal control unit and a memory unit of FIG.

Referring to FIG. 1, the liquid crystal display includes a liquid crystal display panel 100 for displaying an image and a driving circuit 200 for controlling the operation of the liquid crystal display panel 100.

The liquid crystal display panel 100 includes a plurality of unit pixels arranged in a matrix form. The unit pixel is defined by an intersection region of a plurality of gate lines G1 to Gn extending in a row direction and a plurality of data lines D1 to Dm extending in a column direction orthogonal to the gate lines G1 to Gn, And a liquid crystal capacitor (Clc) connected thereto and a storage capacitor (Cst). Although not shown, such a liquid crystal display panel includes a lower substrate on which a switching element Q, a gate line G, a data line D and pixel electrodes are arranged, an upper substrate on which a black matrix, a color filter and a common electrode are arranged, And a liquid crystal layer filled between the two substrates.

A memory unit 250, a signal control unit 210, a voltage generation unit 240, a gate driving unit 220, an image correction unit 250, and a data driving unit 230 are included outside the liquid crystal display panel 100 A driving circuit 200 is provided.

Here, the gate driver 220 and / or the data driver 230 may be mounted on a lower substrate of the liquid crystal display panel 100, on a separate printed circuit board (PCB) And may be electrically connected through a flexible printed circuit board (FPC). It is preferable that the gate driver 220 and the data driver 230 of the present embodiment are manufactured in the form of at least one drive chip and mounted. The signal controller 210, the voltage generator 240, and the image corrector 250 are preferably mounted on a printed circuit board and electrically connected to the liquid crystal display panel 100 through a flexible printed circuit board.

The memory unit 250 stores a plurality of correction data sets that change correction characteristics for each position of the user in image correction. The correction data set is preferably stored in a look-up table (LUT) format. For example, the memory unit 250 may include a first lookup table (LUT1) composed of correction data for providing an optimal image to the left user based on the center of the screen, and a second lookup table And a second lookup table (LUT2) is constructed. Here, the correction data includes adaptive color capture (ACC) data for minimizing the color coordinate deviation of the gradation, DCC (dynamic capacitance compensation) data for determining the maximum value of the gradation response speed, and gamma data . ≪ / RTI > The memory unit 250 alternately selects the first lookup table LUT1 and the second lookup table LUT2 according to the selection signal SS from the signal controller 210 and outputs the selected lookup table LUT1 or LUT2 To the signal controller 210. At this time, the selection signal SS is generated based on the vertical synchronization start signal STV, which is a frame separation signal. Accordingly, in the Nth frame, the first lookup table LUT1 is selected and provided to the signal controller 210. In the (N + 1) th frame, the second lookup table LUT2 is selected and provided to the signal controller 210. [ Here, N is an integer of 1 or more. Meanwhile, the memory unit 250 preferably uses an EEPROM (Electrically Erasable and Programmable Read Only Memory). Of course, in addition to the above-described lookup tables LUT1 and LUT2, the memory unit 250 may further store various lookup tables for generating various control signals. Although the memory unit 250 is provided outside the signal controller 210, the memory unit 250 may be embedded in the signal controller 210 as needed.

The signal control unit 210 includes an image signal processing unit 211 and a control signal generation unit 212. The signal controller 210 receives an external image signal and an external control signal from an external graphic controller (not shown) and receives various lookup tables from the memory unit 250, And generates an internal image signal and an internal control signal.

The image signal processing unit 211 processes the external image data R.G.B in accordance with the operation conditions of the liquid crystal display panel 100 to generate internal image data R'.G'.B '. The internal image data R'.G'.B 'is converted into a digital form and rearranged according to the pixel arrangement of the liquid crystal display panel 100, and the image characteristics are corrected. At this time, the image correction is performed by various methods such as the ACC method, the DCC method, and the gamma compensation method. To this end, the image signal processing section 211 includes at least one or more image correction circuits, such as an ACC circuit, a DCC circuit, .

The control signal generator 212 controls the gate driver 220 based on the external control signals, that is, the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the main clock MCLK, and the data enable signal DE. And a data control signal CS2 for controlling the data driver 230. The data driver 230 generates the data control signal CS2. The control signal generation unit 212 transmits the gate control signal CS1 to the gate driver 220 and the data control signal CS2 to the data driver 230. The gate control signal CS1 includes a vertical synchronization start signal STV, a gate clock signal CPV, and an output enable signal OE that indicate the start of output of the gate-on voltage Von. The data control signal CS2 includes a horizontal synchronization start signal STH indicating the start of transmission of image data R'.G'.B ', a load signal ROAD for applying a data voltage to the data line, And an inverted signal RVS and a data clock signal DCLK for inverting the polarity of the gradation voltage with respect to the gradation voltage. Meanwhile, the control signal generating unit 210 of the present embodiment can generate the gate control signal CS1 and the data control signal CS2 described above by doubling the frame rate when the external image data R.G.B is corrected. Accordingly, the operation clock of the vertical synchronization start signal STV, which is a frame division signal, is doubled from 60 Hz to 120 Hz, and twice the frame is displayed on the screen during the same time. The control signal generation unit 212 generates a selection signal SS for controlling the selection operation of the lookup table and transmits the selection signal SS to the memory unit 250 based on the vertical synchronization start signal STV.

The voltage generator 240 generates and outputs various driving voltages required for driving the liquid crystal display device using an external power source input from an external power source device (not shown). For example, a gate-on voltage Von for turning on the switching element Q, a gate-off voltage Voff for turning off the switching element Q, And generates a gradation voltage Vgma of a plurality of levels applied to a pixel electrode (not shown), a common voltage Vcom applied to a common electrode (not shown), and the like to output it to the data driver 230, .

The gate driver 220 is controlled in accordance with the gate control signal CS1 from the signal controller 210 to generate an analog signal including the gate-on voltage Von and the gate-off voltage Voff input from the voltage generator 240, Signals are sequentially applied to the gate lines G1 to Gn as gate signals.

The data driver 230 is controlled in accordance with the data control signal CS2 from the signal controller 210 so as to output the gradation voltage Vgma corresponding to the internal image data R'.G'.B ' Level, and applies the analog signals including the selected analog signals to the data lines D1 to Dm as data signals.

The liquid crystal display device having such a configuration increases the frame rate by a multiple and uses a plurality of lookup tables (LUT1 and LUT2) that have different correction characteristics for each position of the user for the frames extended in multiples, RGB), and applies the corrected image data (R'.G'.B ') to the liquid crystal display panel 100 to display an image. Accordingly, a screen of a multiple of input is displayed on the liquid crystal display panel 100 for the same period of time. Since the user recognizes the average image characteristic of a plurality of screens providing optimized image characteristics at various positions, It is possible to solve the problem of visibility, in particular, side visibility.

Next, a driving method of a liquid crystal display according to an embodiment of the present invention will be described with reference to FIG. Here, FIG. 3 is a conceptual diagram for explaining correction characteristics of image data per frame.

The control signal generator 212 generates a gate control signal CS1 in response to an external control signal and transmits the gate control signal CS1 to the gate driver 220 and the data driver 230 to generate a data control signal CS2. At this time, the gate control signal CS1 and the data control signal CS2 are generated on the basis of a higher frame rate, that is, a twice frame rate. For example, when the liquid crystal display device of the present embodiment is applied to a TV product, the gate control signal CS1 and the data control signal CS2 are set on the basis of the frame rate F2 of 120 Hz instead of the frame rate F1 of 60 Hz. Is generated. In addition, the control signal generator 212 generates a selection signal SS synchronized with the vertical synchronization start signal STV, which is a frame separation signal, and transmits the generated selection signal SS to the memory unit 250.

The memory unit 250 alternately selects the first lookup table LUT1 and the second lookup table LUT2 in accordance with the selection signal SS from the control signal generator 212 and outputs the selected lookup table LUT1 or LUT2 To the image signal processing unit 211. [ Accordingly, in the Nth frame, the first lookup table LUT1 is selected and provided to the image signal processing unit 211. In the (N + 1) th frame, the second lookup table LUT2 is selected and supplied to the image signal processing unit 211 / RTI > Here, N is an integer of 1 or more.

The image signal processing unit 211 converts the external image data RGB into a digital form and rearranges it in accordance with the pixel arrangement of the liquid crystal display panel 100 and corrects the image characteristic to generate internal image data R'.G ' . At this time, the image signal processing unit 211 performs image correction on the image data (RGB) of the frame using the first lookup table LUT1 or the second lookup table LUT2 provided from the memory unit, The image correction is performed using the first lookup table LUT1 and the image correction is performed using the second lookup table LUT2 in the (N + 1) th frame.

The gate driver 220 sequentially applies a gate signal to each of the gate lines G1 to Gn to turn on the switching element Q of the specific gate line G so that a scan line Select sequentially.

The data driver 230 sequentially receives the corrected image data R'.G'.B 'from the signal controller 210 and receives the gradation voltages Vgma of the plurality of levels generated by the voltage generator 240 A data signal is generated by selecting the gradation voltage of a specific level corresponding to the corrected image data (R'.G'.B '), and the data signals corresponding to the pixels of one row are selected by the gate driver 220 .

On the other hand, all the pixels of the liquid crystal display panel 100 are charged with voltages under the control of the driving circuit 200, and an electric field is formed in the liquid crystal layer. That is, data signals having a potential level suitable for the display gradation are applied to the pixel electrodes, a common voltage Vcom is applied to the common electrodes, and an electric field is formed between the two electrodes, And the transmittance of the light incident on the back surface is changed. The light provided from a backlight unit (not shown) positioned on the back surface of the liquid crystal display panel 100 is transmitted through the liquid crystal layer to form an upper substrate having red (R), green (G), and blue The color image is emitted by the color filter and emitted to the front surface, and the light emitted from each pixel is mixed to realize a color image.

4 is a conceptual diagram for explaining the visual characteristics of the output image for each frame.

Referring to FIG. 4, as the frame rate is doubled, twice as many frames are displayed on the liquid crystal display panel 100 during the same time. At this time, the screen corresponding to the N-th frame (FIG. 4A) is image-corrected using the first look-up table LUT1, and thus has the image characteristic gamma 1 to the left user. On the other hand, the image corresponding to the (N + 1) th frame (FIG. 4B) is image-corrected using the second lookup table LUT2, and thus has the image characteristic? 2 optimized for the right user. Since these two screens are alternately displayed during the time of displaying the original one screen, the user recognizes the two screens as one screen in which the two screens overlap. That is, the user recognizes the average image characteristics of the two screens optimized for the left side and the right side. As a result, a screen having an image characteristic that is uniform regardless of the position of the user is provided, thereby improving visibility, particularly, side viewability.

Meanwhile, the image correction method according to the present embodiment performs image correction based on the left and right users of the liquid crystal display panel, but the present invention is not limited to this, and image correction may be performed based on users at various positions . For example, the image can be corrected based on the upper and lower users of the liquid crystal display panel, and the image can be corrected based on the upper left and lower right users of the liquid crystal display panel.

In addition, the image correction method according to the present embodiment can be applied to various types of liquid crystal display devices. For example, the liquid crystal molecules are horizontally aligned TN, the liquid crystal molecules are vertically aligned, or the VA method is improved to form a plurality of season patterns on at least one of the pixel electrode and the common electrode, The present invention can be applied to a liquid crystal display device such as a PVA method in which a domain is formed or an SPVA method in which a plurality of domains are formed by forming main pixels and sub-pixels in a unit pixel by improving the PVA method.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Accordingly, those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the spirit of the following claims.

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

FIG. 2 is a detailed block diagram of the signal control unit and the memory unit of FIG. 1;

3 is a conceptual diagram for explaining correction characteristics of image data per frame;

4 is a conceptual diagram for explaining a visual characteristic of an output image per frame;

≪ Explanation of Protection for Major Parts of the Drawings >

100: liquid crystal display panel 210:

220: Gate driver 230: Data driver

240: voltage generating unit 250: memory unit

Claims (15)

A liquid crystal display panel for displaying an image; A gate driver for applying a gate signal to the liquid crystal display panel, A data driver for applying a data signal to the liquid crystal display panel, And a signal controller for controlling the gate driver and the data driver, Wherein the signal control unit comprises: A control signal generation unit for increasing a frame rate by a multiple and an image signal processing unit for correcting image data of a frame by alternately using a plurality of correction data sets having different correction characteristics for a frame expanded in multiples, Wherein the plurality of correction data sets have different correction characteristics for each position of the user. The method according to claim 1, And a memory unit for storing the plurality of correction data sets. delete The method according to claim 1, Wherein the plurality of correction data sets include a first lookup table composed of correction data for providing an optimal image to the left user based on the center of the screen and a second lookup table configured of correction data for providing an optimal image to the right user . The method of claim 4, Wherein the correction data includes at least one of data for ACC correction, data for DCC correction, and data for gamma correction. The method of claim 4, Wherein the first and second lookup tables are alternately selected by a selection signal and provided to the image signal processing unit. The method of claim 6, Wherein the selection signal is generated based on a vertical synchronization start signal generated by the control signal generation unit. The method according to claim 1, Wherein the image signal processing section includes at least one of an ACC circuit, a DCC circuit, and a gamma compensation circuit. The method according to claim 1, Wherein the control signal generator increases the frame rate of 60 Hz to 120 Hz. delete delete delete delete delete delete

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