KR101510901B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is disclosed.

The liquid crystal display device according to the present invention can compare the previous frame data with the current frame data to improve the moving image display quality by controlling the driving timing of the light source located in the region where the data difference is severe.

Scanning backlight, drive timing, PWM duty ratio, data comparison

Description

[0001] Liquid crystal display device [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of improving moving image display quality.

A typical liquid crystal display device has an image realization principle using optical anisotropy and polarization property of liquid crystal. The liquid crystal has optical anisotropy having a long and narrow molecular structure and a directional arrangement, and a molecular alignment direction Lt; / RTI >

A liquid crystal display device includes a liquid crystal panel in which a pair of substrates each having a transparent electric field generating electrode formed on a surface facing each other with a liquid crystal layer interposed therebetween and an electric field between two electric field generating electrodes of the liquid crystal panel The light emitted from the backlight unit located on the back surface of the liquid crystal panel is allowed to pass therethrough so that the difference in transmittance is manifested externally so that various images are displayed do.

The backlight unit is generally a hold type in which the lamp, which is a light source, is kept on during a period of displaying an image.

Although CRTs most commonly used in the past for TVs are impulse type display devices, the hold type liquid crystal display devices are not suitable for motion blur which can not display a clear image when the response speed of the liquid crystal is smaller than one frame (Motion Blur) phenomenon occurs.

In order to solve such a disadvantage, a scanning backlight system has been proposed in which a plurality of lamps are arranged in a direct lowering manner and sequentially turned on and off (On, Off). In such a scanning backlight system, motion blur can be reduced by sequentially turning on / off the lamps arranged for each block.

The ramps arranged for each block have an on / off period of a predetermined duty ratio from the first ramp to the n th ramp sequentially in synchronization with the vertical synchronization signal Vsync, The duty ratio is preferably set to have an on period of 60% in one frame. Therefore, the liquid crystal panel is driven similarly to the impulse driving between blocks corresponding to the lamps of the on / off state of the backlight unit, thereby improving the motion blur of the image.

However, such a scanning backlight type liquid crystal display generally controls the ON / OFF period of the lamp at the same duty ratio at the same time without taking the shape of the moving image into consideration, and accordingly, the luminance of the moving image as a whole There is a problem of deterioration. Particularly, according to whether the difference between the previous frame and the current frame is large, the motion blur phenomenon is differently improved according to whether it is the outer part or the central part of each block.

In the present invention, data of a previous frame is compared with data of a current frame to control a driving timing of a light source located in a region where data differences are severe, thereby improving a motion blur phenomenon for each region, And an object of the present invention is to provide a liquid crystal display device capable of improving the display quality.

A liquid crystal display according to an exemplary embodiment of the present invention includes an input unit for inputting data, a memory unit for storing data from the input unit for one frame, a liquid crystal panel for displaying an image corresponding to the data, A plurality of light sources disposed on a rear surface of the liquid crystal panel to provide light to the liquid crystal panel; a lamp driver for driving the plurality of light sources in a plurality of block units; A data analyzer for comparing the current frame data input during the current frame from the input unit with previous frame data stored for one frame in the memory unit and generating a comparison signal according to the comparison result; A PWM duty controller for adjusting a duty ratio of a plurality of light sources divided into the plurality of block units according to a value of the PWM duty It includes parts.

The liquid crystal display according to the present invention compares the data of the previous frame with the data of the current frame to control the driving timing of the light source located in the region where the difference of data is severe and the driving timing of the liquid crystal located in the region, The driving timing of the liquid crystal is made different, and the motion blur phenomenon can be similarly improved for each region.

Further, the liquid crystal display device according to the present invention can improve the display quality of a moving image.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

1 is a view illustrating a liquid crystal display device according to an embodiment of the present invention.

1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel 102 in which a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm are arranged and displays an image, A gate driver 104 for driving the plurality of gate lines GL1 to GLn; a data driver 106 for driving the plurality of data lines DL1 to DLm; A timing controller 108 for controlling the driving timing of the liquid crystal panel 102 and a backlight unit 110 for providing light to the liquid crystal panel 102.

The liquid crystal panel 102 includes pixels formed in regions divided by a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm. Each of these pixels includes a thin film transistor TFT formed at an intersection between a corresponding gate line GL and a corresponding data line DL and a thin film transistor TFT formed between the thin film transistor TFT and the common electrode Vcom, (Clc). The thin film transistor TFT switches the pixel data voltage to be supplied to the corresponding liquid crystal cell Clc from the corresponding data line DL in response to the gate scan signal on the corresponding gate line GL. At this time, the liquid crystal panel 102 is divided into first to third blocks I to III.

The gate driver 104 responds to the gate control signals GCS from the timing controller 108 so that the plurality of gate lines GL1 to GLn are supplied with a plurality of scan signals in a corresponding manner Supply. The plurality of scan signals cause the plurality of gate lines GL1 to GLn to sequentially enable one horizontal synchronization signal period.

In response to the data control signals DCS from the timing controller 108, the data driver 106 generates a plurality of pixel data voltages whenever one of the plurality of gate lines GL1 to GLn is enabled And supplies them to the plurality of data lines DL1 to DLm on the liquid crystal panel 102, respectively.

To this end, the data driver 106 inputs pixel data for one line from the timing controller 108, and converts input pixel data of one line into an analog pixel data voltage using a gamma voltage set .

The timing controller 108 receives synchronization signals (Vsync, Hsync) supplied from an external system (for example, a graphics module of a computer system or a video demodulation module of a television receiving system, not shown) A gate control signal GCS for controlling the gate driver 104 and a data control signal DCS for controlling the data driver 106 are generated using a clock signal DE and a clock signal CLK. The timing controller 108 sorts data supplied from an external system and supplies the sorted data to the data driver 106.

The backlight unit 110 includes a plurality of lamps (not shown) disposed on the back surface of the liquid crystal panel 102 and generating light, a light source unit 120 for diffusing and condensing the light generated from the lamps, An optical sheet (not shown) for providing the liquid crystal panel 102, and components for fastening with the liquid crystal panel 102. Each of the lamps located in the first to third blocks (I to III) is driven in a scanning backlight manner.

In addition, the liquid crystal display according to the embodiment of the present invention includes a data conversion unit 112 for receiving data arranged in a pixel-by-pixel order from the timing controller 108 and converting the data into data for each predetermined area, A memory unit 114 for storing data converted by a predetermined area from the data conversion unit 112 for one frame for each of the first to third blocks I to III; A data analysis unit 116 for comparing the stored previous frame data with the data input in the current frame from the data conversion unit 112, The PWM duty controller 118 for controlling the duty ratio of the lamps located in each of the blocks I to III and the first to third blocks I to III according to the duty ratio controlled by the PWM duty controller 118, On / Off < / RTI > < RTI ID = 0.0 & and a lamp driving unit 120 for generating a lamp driving voltage to be applied to the LCD panel.

The data converter 112 divides a plurality of pixels into one area, calculates an average value of data corresponding to a plurality of pixels included in the one area, Into data of the one area.

2, the data conversion unit 112 divides 4 by 4 pixels into one area and stores the data corresponding to 4 by 4 pixels, for example, An average value is obtained and converted into data of one area. The reason why the data conversion unit 112 performs the above operation is to reduce the capacity of the data sorted by the pixels from the timing controller 108.

The data converted by the data conversion unit 112 is supplied to the memory unit 114 and the data analysis unit 116, respectively.

The memory unit 114 includes first to third memories 114a to 114c to correspond to the first to third blocks I to III of the liquid crystal panel 102. The data stored in the first memory 114a corresponds to the first block I of the liquid crystal panel 102 and the data stored in the second memory 114b corresponds to the data stored in the second memory 114b. The data corresponding to the second block II and the data stored in the third memory 114c correspond to the third block III of the liquid crystal panel 102.

The memory unit 114 stores the data supplied from the data conversion unit 112 for one frame and supplies the data to the data analysis unit 116.

The data analyzer 116 includes first through third block data analyzers 116a through 116c corresponding to the first through third blocks I through III of the liquid crystal panel 102. [ The data analysis unit 116 receives data from the data conversion unit 112 and data stored for one frame from the memory unit 114. The data analyzing unit 116 receives data corresponding to the current frame from the data converting unit 112 and data corresponding to a previous frame stored for one frame from the memory unit 114. [

The first block data analyzing unit 116a receives the current frame data corresponding to the first area I of the liquid crystal panel 102 from the data converting unit 112 and the current frame data corresponding to the first area I of the memory unit 114 (I) stored in the first region (I) 114a.

The first block data analyzer 116a compares the current frame data with previous frame data and calculates a difference value. When the calculated difference value is greater than a predetermined reference value, the first block data analyzer 116a performs base logic (e.g., Low) of the first comparison signal. The first block data analyzer 116a generates a second comparison signal having a specific logic (for example, High) when the calculated difference value is smaller than the reference value. The first and second comparison signals generated by the first block data analyzer 116a are supplied to the PWM duty controller 118. The reference value is data corresponding to a portion where the degree of change is significant in the current frame and the previous frame. Therefore, when the calculated difference value is larger than the reference value, it is highly likely that a motion blur phenomenon occurs when a moving image is implemented.

The second block data analyzing unit 116b receives the current frame data corresponding to the second block II of the liquid crystal panel 102 from the data converting unit 112 and the current frame data corresponding to the second block II of the memory unit 114 And the previous frame data corresponding to the second area II stored in the second area 114b.

The second block data analyzing unit 116b compares the current frame data with the previous frame data and calculates the difference value. When the calculated difference value is larger than a preset reference value, the second block data analyzing unit 116b performs base logic (e.g., Low) of the first comparison signal. The second block data analyzing unit 116b generates a second comparison signal having a specific logic (for example, High) when the calculated difference value is smaller than the reference value. The first and second comparison signals generated by the second block data analysis unit 116b are supplied to the PWM duty control unit 118. [

The third block data analyzing unit 116c receives the current frame data corresponding to the third block III of the liquid crystal panel 102 from the data converting unit 112 and the current frame data corresponding to the third block III of the memory unit 114 And the previous frame data corresponding to the third area (III) stored in the second area (114c).

The third block data analyzing unit 116c compares the current frame data with the previous frame data and calculates the difference value. When the calculated difference value is greater than a preset reference value, the third block data analyzing unit 116c performs base logic (for example, Low) of the first comparison signal. The third block data analyzer 116c generates a second comparison signal having a specific logic (for example, High) when the calculated difference value is smaller than the reference value. The first and second comparison signals generated by the third block data analyzer 116c are supplied to the PWM duty controller 118.

The PWM duty controller 118 also includes first to third PWM duty controllers 118a to 118c corresponding to the first to third blocks I to III of the liquid crystal panel 102. [ The first and second comparison signals from the first block data analysis unit 116a are supplied to the first PWM duty control unit 118a and the first and second comparison data from the second block data analysis unit 116b Signal is supplied to the second PWM duty controller 118b and the first and second comparison signals from the third block data analyzer 116c are supplied to the third PWM duty controller 118c.

The first to third PWM duty controllers 118a to 118c are turned on according to a comparison signal from the first to third block data analyzers 116a to 116c, And the OFF period.

When the first comparison signal is supplied from the first through third block data analyzers 116a through 116c, the first through third PWM duty controllers 118a through 118c each count the number of times the first comparison signal is supplied The lamp is turned off. When the second comparison signal is supplied from the first through third block data analyzers 116a through 116c to the first through third PWM duty controllers 118a through 118c, So that the lamp is turned ON from the moment.

When the first comparison signal is supplied to the first to third PWM duty controllers 118a to 118c, when the moving image is displayed on the liquid crystal panel 102, the difference between the data of the previous frame and the data of the current frame is smaller than the reference value In this case, the lamp is turned off. By turning off the lamp, a motion blur phenomenon can be prevented.

Signals having duty ratios controlled by the first to third PWM duty controllers 118a to 118c are supplied to the corresponding first to third block lamp drivers 120a to 120c.

The signal of the duty ratio adjusted by the first PWM duty controller 118a is supplied to the first block lamp driver 120a and the signal of the duty ratio adjusted by the second PWM duty controller 118b is supplied to the first block lamp driver 120a. And the signal of the duty ratio adjusted by the third duty control unit 118c is supplied to the third block lamp driving unit 120c.

The first through third block ramp drivers 120a through 120c are arranged in the first through third blocks I through III according to signals supplied from the first through third PWM duty controllers 118a through 118c. The lamp is driven.

As described above, the ramps disposed in the first to third blocks I to III are turned off when the difference between the previous frame data and the current frame data in each of the blocks I to III is larger than the reference value, do. When the difference between the previous frame data and the current frame data in the first block I of the first through third blocks I through III is greater than the reference value, the ramp arranged in the first block I is OFF ) do.

As the difference between the previous frame data and the current frame data is larger, a motion blur phenomenon frequently occurs when a moving image is implemented. To prevent such a phenomenon, a lamp having a large difference between the previous frame data and the current frame data is turned off ). When the liquid crystal positioned in a region where the difference between the previous frame data and the current frame data is larger than the reference value responds to the current frame data, the lamp disposed in the region is turned off to prevent motion blur do.

3A is a diagram showing on / off intervals of the lamps arranged in the first to third blocks I to III when the image change is severe at the central portion of the third block III, Off periods of the lamps arranged in the first to third blocks I to III when the image change is severe at the edge of the third pixel (III).

As shown in FIGS. 3A and 3B, when the portion where the image change is severe is the edge of the third block III (hereinafter referred to as "first case"), the light source corresponding to the third block III The third section (3) in which the in-ramp is turned on is the third block (III) in the case where the portion where the image change is severe is the central portion of the third block (III) Is delayed from the first section (1) in which the corresponding lamp is turned ON.

Accordingly, in the first case, the lamp corresponding to the third block (III) is turned off in the fourth section (4), which is the timing at which the vehicle moves (the timing at which the liquid crystal responds) from the image. The fourth section (4) is delayed from the second section (2), which is a section in which the lamp corresponding to the third block (III) is turned off in the second case, .

As a result, in the liquid crystal display according to the present invention, on a liquid crystal panel divided into a plurality of blocks, a lamp arranged corresponding to each block is turned off according to the degree of difference between previous frame data and current frame data in each block , And a motion blur phenomenon can be prevented. Further, the liquid crystal display device according to the present invention can improve motion picture display quality by preventing a motion blur phenomenon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view illustrating a liquid crystal display device according to an embodiment of the present invention. FIG.

Fig. 2 is a diagram showing an example of data conversion by the data conversion unit of Fig. 1; Fig.

FIG. 3A is a diagram showing on / off intervals of the lamps arranged in the first to third blocks I to III when the image change is severe at the central portion of the third block III; FIG.

FIG. 3B is a view showing on / off intervals of the lamps arranged in the first to third blocks I to III when the image change is severe at the edge of the third block III.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

102: liquid crystal panel 104: gate driver

106: Data driver 108: Timing controller

110: backlight unit 112: data conversion unit

114: memory units 114a to 114c: first to third memories

116: Data analysis unit 118: PWM duty control unit

116a to 116c: the first to third block data analysis units

118a to 118c: the first to third pwm duty controllers

120:

120a to 120c: first to third block lamp driving units

Claims (8)

An input unit for inputting data; A memory unit for storing data from the input unit for one frame; A liquid crystal panel displaying an image corresponding to the data and including a plurality of pixels; A driving unit for driving the liquid crystal panel; A plurality of light sources disposed on a rear surface of the liquid crystal panel to provide light to the liquid crystal panel; A lamp driver for driving the plurality of light sources in units of blocks; A data analyzer for comparing current frame data input during a current frame from the input unit with previous frame data stored for one frame in the memory unit and generating a comparison signal according to the comparison result; And And a PWM duty controller for adjusting a duty ratio of a plurality of light sources divided into the plurality of block units according to a logical value of a comparison signal from the data analyzer, Wherein the PWM duty control unit varies the lighting start timing of each of the plurality of block units according to a logical value of the comparison signal. The method according to claim 1, Further comprising a data conversion unit located between the input unit and the memory unit and dividing the plurality of pixels into a predetermined area, calculating an average value of the data included in the predetermined area, and supplying data corresponding to the average value to the memory unit The liquid crystal display device according to claim 1, The method according to claim 1, Wherein the lamp driving unit sequentially drives a plurality of light sources divided into the plurality of block units according to the duty ratio adjusted from the PWM. The method according to claim 1, The data analyzer calculates a difference value between the current frame data and previous frame data, compares the calculated difference value with a reference value, generates a comparison signal according to the comparison result, and supplies the comparison signal to the PWM duty controller Wherein the liquid crystal display device is a liquid crystal display device. 5. The method of claim 4, Wherein the reference value is a difference value between the current frame data and the previous frame data corresponding to a degree of the degree of change in the previous frame and the current frame that can cause a motion blur phenomenon. 5. The method of claim 4, The data analyzer generates a first comparison signal of the base logic when the difference value between the current frame data and the previous frame data is greater than the reference value, and when the difference value is smaller than the reference value, And supplies the first and second comparison signals to the PWM duty control unit. The method according to claim 6, The PWM duty controller may adjust the duty ratio to turn off the plurality of light sources divided into the plurality of block units when the first comparison signal is supplied and to turn on the plurality of light sources when the second comparison signal is supplied And the duty ratio is adjusted. The method according to claim 1, Wherein the liquid crystal panel is divided into regions corresponding to the plurality of block units, Wherein the data analyzer compares previous frame data corresponding to each of the divided regions of the liquid crystal panel with current frame data.

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