KR20120070196A - Liquid crystal display device and driving method for thereof - Google Patents

Abstract

PURPOSE: A liquid crystal display device and a driving method thereof are provided to prevent a color breaking phenomenon in a field sequential color operation. CONSTITUTION: A MEMC(Motion Estimated Motion Compensation) process is performed with respect to a G video signal and a B video signal. A source R video signal, the G video signal, and the B video signal are time-sequentially arranged. An FSC(Field Sequential Color) video signal of a first frame is created. An RGB video is successively displayed on a liquid crystal panel.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY DEVICE AND DRIVING METHOD FOR THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly, to a liquid crystal display device and a driving method thereof, which can improve display quality by preventing color breakup when driving a field sequential color.

The display device has been developed according to the market demand for larger size and thinner, and the demand for a flat panel display device having advantages of thin film, light weight, and low power consumption is increasing.

As a flat panel display device, a liquid crystal display device, a plasma display panel, a field emission display device, and a light emitting diode display device are used as a flat panel display device. ) And organic light emitting diode display devices have been developed.

Among flat panel display devices, the liquid crystal display device has secured a firm market due to the development of mass production technology, ease of driving means, low power consumption, thin thickness, high definition and large screen, and its application field is expanding.

The liquid crystal display includes a liquid crystal panel in which a plurality of pixels (liquid crystal cells) are arranged in a matrix form; A backlight unit for supplying light to the liquid crystal panel; And a driving circuit unit for driving the liquid crystal panel and the backlight.

The liquid crystal display displays an image by adjusting the transmittance of light emitted from the backlight unit for each pixel of the liquid crystal panel according to the input image signal.

The liquid crystal display may classify an image into a space division method and a time division method according to a method of displaying a color image.

The spatial division method displays an image by spatially dividing an image of R, G, and B, and displays an image by configuring one pixel with subpixels of R, G, and B. The backlight irradiates white light to the liquid crystal panel and includes color filters of R, G, and B on the upper substrate. As a result, a color image is displayed by combining color gray levels of subpixels of R, G, and B colors.

The time division scheme is to divide R, G, and B images in time and display images, and a field sequential color (FSC) scheme has been proposed.

1 is a view showing a driving method of a liquid crystal display device driven by the FSC method according to the prior art.

Referring to FIG. 1, an FSC type liquid crystal display according to the related art displays an image by sequentially driving a light emitting diode (hereinafter, referred to as “LED”) generating color light of R, G, and B. FIG. In this case, the FSC type liquid crystal display does not include a separate color filter on the upper substrate of the liquid crystal panel.

In detail, one frame is divided into three subframes of R, G, and B, and the R, G, and B colors are sequentially irradiated onto the liquid crystal panel with a predetermined interval therebetween to display an image.

The FSC type liquid crystal display does not divide one pixel into sub-pixels of R, G, and B, and transmits three primary colors of light supplied from the LEDs of R, G, and B to one pixel through the liquid crystal panel. Split and display sequentially. Color light of R, G, and B displayed by being divided in time is displayed as a color image by using the afterimage effect of the human eye.

In the liquid crystal display of the field sequential driving method according to the prior art, the R, G, and B LEDs are sequentially flashed to display an image, and the position where the color light emitted from the LEDs of the R, G and B is recognized by the human eye is determined. Differently, a color breakup phenomenon occurs in which colors (for example, white) in which R, G, and B color light are combined are not recognized.

In 60Hz (1/60 sec) driving method, when the image moves from left to right or from right to left, each signal of R, G, B is delayed by 1/180 sec of R, G, B, component of the same signal. This results in display of color, which causes color breakup at the boundary of the image.

The color cracking phenomenon according to the FSC method is caused by the time difference according to the display of the R, G, and B areas, and when an image displayed with the mixed colors of the three primary colors of R, G, and B moves along the screen, that is, the video is displayed. The case is more pronounced.

Since R, G, and B signals are separated from the original image (60 Hz), the R, G, and B signals at 180 Hz are sequentially driven, so that R, G, and B signals having the same position information are displayed with a time difference of 1/180 sec. Will be. Therefore, color breakage occurs due to a disparity between the movement of the line of sight and the display image, thereby degrading the display quality of the video.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a liquid crystal display and a driving method thereof capable of preventing color breakup when driving field sequential colors. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a liquid crystal display and a driving method thereof capable of improving display quality of a video when driving field sequential colors.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

According to an exemplary embodiment of the present invention, a driving method of an image display apparatus may include a motion estimated motion compensation (MEMC) for the G image signal and the B image signal except for the source R image signal among the source R, G, and B image signals input from the outside. Performing); Generating an FSC image signal of one frame by sequentially arranging the source R image signal, the G image signal formed by MEMC, and the B image signal; And sequentially displaying R, G, and B images on the liquid crystal panel by using the FSC image signal of the one frame.

In the method of driving an image display device according to an exemplary embodiment of the present invention, the source R image signal, the G image signal including the MEMC, and the B image signal have different position information.

The driving method of an image display device according to an exemplary embodiment of the present invention is characterized in that positions of R, G, and B images sequentially displayed on the liquid crystal panel are different from each other.

In the driving method of an image display device according to an exemplary embodiment of the present invention, the position of a pixel on which the R, G, and B images are displayed is moved on the liquid crystal panel in consideration of the movement of a gaze according to the time difference between the R, G, and B images. It is characterized by.

The driving method of the image display apparatus according to an exemplary embodiment of the present invention is characterized by displaying the R, G, and B images at positions consistent with the movement of the gaze.

An image display device according to an embodiment of the present invention performs a motion estimation motion compensation (MEMC) on the G image signal and the B image signal except for the source R image signal among the source R, G, and B image signals input from the outside. An image converter; A timing controller for arranging the source R video signal, the G video signal formed by MEMC, and the B video signal sequentially in time to generate an FSC video signal of one frame; A data driver for converting the FSC video signal of one frame into R, G, and B analog video data; And a liquid crystal panel that sequentially displays R, G, and B images using the R, G, and B analog image data.

The image converter of the image display device according to an exemplary embodiment of the present invention converts the source R, G, and B image signals input at a 60 Hz driving frequency into an FSC image signal having a 180 Hz driving frequency, and the source R image signal and the MEMC. It is characterized in that the different position information is given to the G video signal and the B video signal.

The present invention can provide a liquid crystal display and a driving method thereof that can prevent color breakup when driving a field sequential color.

According to an exemplary embodiment of the present invention, a liquid crystal display and a driving method thereof capable of improving display quality of a video when driving a field sequential color may be provided.

In addition, other features and advantages of the present invention may be newly understood through the embodiments of the present invention.

1 is a view showing a driving method of a liquid crystal display device driven by the FSC method according to the prior art.
2 is a view illustrating a driving method of a liquid crystal display according to an exemplary embodiment of the present invention.
3 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
4 is a diagram illustrating a driving method of an image converter according to an exemplary embodiment of the present invention.
5 is a diagram illustrating a backlight (LED) configuration of a liquid crystal display according to an exemplary embodiment of the present invention.

Hereinafter, an image display device and a driving method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a diagram illustrating a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a liquid crystal display according to an exemplary embodiment of the present invention prevents color breakage when driving an FSC method that displays input R, G, and B image signals by time division.

Analyze the input R, G, and B video signals, and use the input source signal as the R signal among the R, G, and B video signals, and estimate the motion and correct the motion of the G and B video signals. Motion Compensation, hereinafter referred to as 'MEMC' to convert the image.

The converted image signals, that is, the source R image signal, the MEMC1 G signal, and the MEMC2 B signal are sequentially displayed at a time difference of 1/3 frame to implement a color image. At this time, the display R, G, and B subframes are displayed by different position information on the liquid crystal panel (screen) with a difference of 1/3 frame.

When the source video signal is input at 60 Hz, the R, G, and B video signals are displayed with a time difference of 1/180 sec, and the liquid crystal panel (screen In this case, the position of the pixel (Pixel) in which the R, G, and B signals are displayed is shifted.

In this way, color movement due to FSC driving may be prevented by matching the movement of the line of sight with the display position of the R, G, and B images. In particular, when the video is implemented, the display quality of the video can be improved by matching the motion of the image with the movement of the gaze so that the boundary of the R, G, and B images is cleanly separated.

3 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is a diagram illustrating a driving method of an image converter according to an exemplary embodiment of the present invention.

3 and 4, the liquid crystal display 100 according to the embodiment of the present invention includes a liquid crystal panel 110; Gate driver 120; Data driver 130; Backlight unit 140; A backlight driver 150; Timing controller 160; And an image converter 170.

The image converter 170 analyzes the input source R, G, and B image signals so that color breakage does not occur when driving the FSC method, and then converts at least one of the source R, G, and B image signals. The conversion is supplied to the timing controller 160.

As an example, the source R video signal is still used, and MEMC is applied to convert the source G signal and the source B signal. Thereafter, the source R video signal and the G video signal and the B video signal that have been subjected to MEMC correction are sequentially arranged in time to generate an FSC video signal. Thereafter, the converted image signal data 'is supplied to the timing controller 160.

The R, G, and B video signals that are input are divided into three subframes and displayed sequentially. Even if the R video signal located in front of the R, G, and B video signals of one frame is displayed in the FSC method, time difference does not occur. Do not.

However, the G image signal displayed after the R image signal is displayed with a time difference of 1/3 frame compared to the R image signal, and the B image signal displayed after the G image signal is 2/3 compared to the R image signal. Displayed with parallax as much as the frame.

When a source R, G, B video signal input at a driving frequency of 60 Hz from the outside is input, the R, G, B video signal 1/180 sec without inputting the 60 Hz input video to the timing controller 160 as it is. MEMC is performed on the source R, G, and B video signals to sequentially display the difference, thereby generating the converted video signals R, G 'B'. Thereafter, the converted image signals R and G 'B' are supplied to the timing controller 160.

Specifically, the R image signal is extracted from the input source R, G, and B image signals, and the extracted R image signal is supplied to the timing controller 160 without conversion.

Image conversion is performed on the G image signal and the B image signal, and the converted image signals R and G 'B' are supplied to the timing controller 160.

Here, the MEMC1 is extracted from the input source R, G, and B image signals, and performs MEMC on the extracted G signal, and MEMC1 is provided with position information of pixels displayed according to parallax and gaze movement of the display image. The G data is supplied to the timing controller 160.

Then, the B image signal is extracted from the input source R, G, and B image signals, and MEMC is performed on the extracted B signal to give the MEMC2 B data to which position information is displayed according to parallax and gaze movement of the display image. Is supplied to the timing controller 160.

As a result, when the source R, G, and B image signals input from the outside are sequentially divided and displayed sequentially, the R, G, and B images of the R, G, and B subframes constituting one frame are displayed in the liquid crystal panel 110. ) In different positions within the

The timing controller 160 aligns the image signal data input from the image converter 170 into digital image data in units of frames, and supplies the digital image data arranged in units of frames to the data driver 130.

In this case, the image signal data 'input from the image converter 170 performs MEMC on the G signal and the B signal excluding the R signal from the external source image signals R, G, and B. In the panel 110, the display position of the G image and the B image according to the converted G ′ signal and the converted B ′ signal is changed.

In addition, the timing controller 160 uses the input vertical sync signal Vsync, the horizontal sync signal Hsync, and the clock signal CLK to control the gate control signal GCS and data for controlling the gate driver 120. The data control signal DCS for controlling the driver 130 is generated. The generated gate control signal GCS is supplied to the gate driver 120, and the data control signal DCS is supplied to the data driver 130.

The data control signal DCS may include a source start pulse (SSP), a source sampling clock (SSC), a source output enable (SOE), and a polarity control signal (POL). Polarity) and the like.

The gate control signal GCS may include a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like.

In addition, the timing controller 160 operates a backlight control signal (BLCS: Back Light) for driving the light source (LED) of the backlight unit 140 in synchronization with image data supplied to the liquid crystal panel 110 through the data driver 130. The control signal is generated and the generated backlight control signal BLCS is supplied to the backlight driver 150. In this case, the backlight control signal BLCS is generated in accordance with the FSC scheme so that the plurality of LEDs are driven in synchronization with the image data supplied to the liquid crystal panel 110.

The gate driver 120 generates a scan signal for driving a TFT formed in each of the plurality of pixels based on a gate control signal (GCS) from the timing controller 160. .

The generated scan signal is sequentially supplied to a plurality of gate lines formed in the liquid crystal panel 110 during one frame period, and TFTs formed in each pixel are driven by the scan signal to switch pixels.

The data driver 130 converts digital image data supplied from the timing controller 160 into analog R, G, and B image data, that is, R, G, and B data voltages.

In addition, based on a data control signal (DCS: Data Control Signal) from the timing controller 160, the analog R, G, and B image data converted according to the time point at which the TFT of each pixel is turned on are sequentially formed. Supply to a plurality of data lines formed in 110.

In this case, when the source video signal is input at a driving frequency of 60 Hz, the source video signals of R, G, and B are converted into R, G, and B video signals of 180 Hz. Analog image data of R, G, and B are sequentially input to the liquid crystal panel 110 at intervals of 1/180 sec.

The liquid crystal panel 110 implements a color image by sequentially displaying R, G, and B image data which is driven by an FSC method, and includes a plurality of gate lines G1 to Gn and a plurality of data lines D1 to Dm. ).

A plurality of pixels is formed in each region defined by the intersection of the plurality of gate lines and the plurality of data lines. The plurality of pixels includes a storage capacitor Cst and a thin film transistor (TFT).

The source video signal of 60Hz is converted into R, G, and B video signals of 180Hz in accordance with FSC driving, and is supplied to each of three R, G, and B analog video data pixels at 1/180 sec intervals.

The liquid crystal of each pixel behaves by the input analog image data of R, G, and B, and R, G, and B color light are sequentially displayed according to the light transmittance of the liquid crystal.

Through this, the liquid crystal panel 110 sequentially displays R, G, and B images with a 1/180 sec difference, and the R, G, and B images are fused by an afterimage effect to implement a color image.

Since the liquid crystal panel 110 does not generate self-emission, the liquid crystal panel 110 displays an image by using light supplied from the backlight unit 140.

The backlight unit 140 is for irradiating light to the liquid crystal panel 110. The backlight unit 140 guides the plurality of LEDs (Light Emitting Diodes) and the light generated from the LEDs toward the liquid crystal panel. It comprises an optical member (light guide plate, diffuser plate, a plurality of optical sheets) for improving the efficiency of light.

The backlight unit 140 has a direct type in which the backlight is disposed in the lower direction of the liquid crystal panel 110 according to the structure in which the backlight is disposed, and an edge in which the backlight is disposed in the lateral direction of the liquid crystal panel 110. Can be distinguished by type. The image display device and its driving method according to an embodiment of the present invention can be applied to both the direct type and the edge type.

5 is a diagram illustrating a backlight (LED) configuration of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 5, in the liquid crystal display device 100 of the present invention, the backlight may include LEDs emitting three colors of light of red, green, and blue.

However, the present invention is not limited thereto, and in addition to the three colors of red, green, and blue, any one of yellow, cyan, magenta, and white colors may be used. It may be composed of LEDs for emitting four colors of light further comprising an LED for generating a.

In addition to the three colors of red, green, and blue, LEDs that generate at least two color lights of yellow, cyan, magenta, and white may be used. It may further comprise LEDs that emit five to seven colors of light.

The backlight driver 150 controls the driving (on-off) of the plurality of LEDs, and the on-off time of each of the plurality of LEDs is based on the backlight control signal BLCS supplied from the timing controller 160. -off time), duty and brightness can be controlled.

Here, the backlight driver 150 controls the on-off timing of each LED based on the backlight control signal BLCS, and also a driving signal for controlling the brightness of the LED (when the backlight is an LED, a PWM signal: pulse width modulation signal), and the generated PWM signal may be used to control luminance of the plurality of LEDs. That is, the backlight driver 150 may control the duty of the PWM signal, which is the LED driving signal, to lower or increase the luminance of LEDs generating unique color light according to the FSC driving.

When the light source of the backlight unit is configured to include not only LEDs of red, green, and blue tricolor lights, but also white LEDs, the luminance of the light supplied to the liquid crystal panel 110 is increased to increase the luminance of the display image. Can be.

In addition, when the light source of the backlight unit includes not only LEDs of red, green, and blue tricolor light, but also additionally LEDs of magenta, cyan and yellow color light, the color display performance can be improved to improve the display quality of the image. have.

In the above description, the source video signal input at 60 Hz is converted to the FSC R, G, and B video signals of 180 Hz, but this is an exemplary embodiment of the present invention. According to another embodiment of the present invention, the input source image signal may be converted into an FSC R, G, and B image signal of 240 Hz, 300 Hz, 360 Hz, and 480 Hz to display a color image in a time division manner.

In the above description, the source video signal and the converted FSC video signal have been described as being in the form of R, G, and B. However, this shows one embodiment of the present invention. In another embodiment of the present invention, the source video signal and the converted FSC video signal are 'G, B, R', 'G, R, B', 'B, G, R', 'B, R, G' or ' It may be formed in the form of R, B, G '.

In the above description, when the source video signal is input in the order of R, G, and B, the source R video signal is used as it is, and the source G video signal and the source B video signal are converted into the MEMC1 G video signal and the MEMC2 B video signal. Although described, this shows one embodiment of the present invention.

When the source video signal is input in the form of 'G, B, R' or 'G, R, B', the source G video signal may be used as it is, and the B video signal and the R video signal may be converted into a MEMC video signal. .

In addition, when the source video signal is input in the form of 'B, G, R' or 'B, R, G', the source B video signal is used as it is and the G video signal and the R video signal are converted into a MEMC video signal. Can be.

In the above description, the image conversion unit 170 has been described as a separate configuration independent of the liquid crystal display device 100. In another embodiment of the present disclosure, the image converter 170 may be embedded in the timing controller 160.

In the above description, the technical matters of the present invention, which prevent color generation when the FSC is driven, have been described as being applied to the liquid crystal display, but this has described an embodiment of the present invention.

The technical idea of preventing color breakage when driving the FSC proposed by the present invention is not only a liquid crystal display device but also another display device that implements a color image through a time division method, for example, a plasma display panel, a field emission display device, an organic display device. The same may be applied to the LED display device.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: liquid crystal display 110: liquid crystal panel
120: gate driver 130: data driver
140: backlight unit 150: backlight driver
160: timing controller 170: image conversion unit

Claims (10)

Performing Motion Estimated Motion Compensation (MEMC) on the G image signal and the B image signal except for the source R image signal among the source R, G, and B image signals input from the outside;
Generating an FSC image signal of one frame by sequentially arranging the source R image signal, the G image signal formed by MEMC, and the B image signal; And
And sequentially displaying R, G, and B images on the liquid crystal panel by using the FSC image signal of the one frame. The method of claim 1,
And the source R image signal, the G image signal formed by the MEMC, and the B image signal have different positional information. The method of claim 1,
The R, G, and B images sequentially displayed on the liquid crystal panel are displayed in different positions from each other. The method of claim 1,
The R, G, and B images are sequentially displayed with a difference of 1/3 frame. The method of claim 1,
A method of driving a liquid crystal display device, characterized by converting a source R, G, B image signal input at a predetermined driving frequency into an FSC image signal having a driving frequency three times the input frequency. The method of claim 1,
A method of driving a liquid crystal display device comprising moving a position of a pixel on which an R, G, or B image is displayed on the liquid crystal panel in consideration of movement of a line of sight according to a time difference in which R, G, and B images are displayed. The method according to claim 6,
And displaying the R, G, and B images at positions coinciding with the movement of the line of sight. An image converter configured to perform MEMC (Motion Estimated Motion Compensation) on the G image signal and the B image signal excluding the source R image signal among the source R, G, and B image signals input from the outside;
A timing controller for arranging the source R video signal, the G video signal formed by MEMC, and the B video signal sequentially in time to generate an FSC video signal of one frame;
A data driver for converting the FSC video signal of one frame into R, G, and B analog video data;
And a liquid crystal panel that sequentially displays R, G, and B images using the R, G, and B analog image data. The method of claim 8, wherein the image converter,
Converts the source R, G, B video signals input at a predetermined driving frequency into FSC video signals having a driving frequency three times the input frequency;
And distributing different positional information to the source R image signal, the G image signal formed by the MEMC, and the B image signal. The method of claim 9,
And moving the positions of the pixels displaying the R, G, and B images on the liquid crystal panel, and displaying the R, G, and B images at positions coinciding with the movement of the line of sight.

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