KR101608636B1 - Apparatus and method for driving liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to a driving apparatus and a driving method of a liquid crystal display capable of improving display quality by driving light emitting diodes (LEDs) of a backlight unit on a block basis.

A driving apparatus for a liquid crystal display according to the present invention includes a timing controller for aligning an input video signal into video data of one frame unit; A data analyzer for analyzing the image data of one frame and setting an LED block so that a plurality of LEDs are driven in the same number of units based on the analysis result of the image data; A dimming value calculating unit for calculating a dimming value of the LED block corresponding to the one frame image data based on the analysis result of the image data and the LED block setting; A dimming value divider dividing the dimming value of the LED block corresponding to the one frame image data into dimming values of LED blocks corresponding to two frames; And an LED driver driving the LED block using a dimming value of the LED block corresponding to the two frames.

Light emitting diodes, block dimming, backlight units, GFI (Gray Field Insertion), motion blur,

Description

TECHNICAL FIELD [0001] The present invention relates to a driving apparatus and a driving method for a liquid crystal display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to a driving apparatus and a driving method of a liquid crystal display capable of improving display quality by driving light emitting diodes (LEDs) of a backlight unit on a block basis.

An active matrix type liquid crystal display device displays an image by adjusting a light transmittance of a liquid crystal through a thin film transistor (TFT) as a switching element. Such a liquid crystal display device is applied to portable information equipment, office equipment, computer and IT products due to advantages such as light weight, thin shape and low power consumption driving, and its application range is widening.

Since the liquid crystal display device is not a self-luminous device, images are displayed using light supplied through a backlight unit provided under the liquid crystal panel. When the transmittance of light passing through the liquid crystal layer of the liquid crystal panel is maximized, the liquid crystal panel realizes a white image with high brightness. When the transmittance of light of the liquid crystal layer is minimized, .

However, since it is difficult for the liquid crystal layer to be arranged in a generally completely constant direction, a light splitting phenomenon may occur at a low tone value. That is, it is difficult for the liquid crystal panel to realize a complete black image at a low tone value, thereby reducing a contrast ratio of an image displayed on the liquid crystal panel.

The liquid crystal display device is driven with 60 to 240 frames per second according to the driving frequency to express a moving image. Due to the holding characteristics of the light source generating the light and the liquid crystal holding characteristics, There is a problem that a motion blur phenomenon that affects the image is generated. Such a motion blur phenomenon is a major cause of degrading the display quality of the liquid crystal display device.

As a method for reducing the motion blur phenomenon, MEMC, scanning backlight, and GIF (Gray Field Insertion) methods have been proposed as shown in FIGS. 1 to 3.

Referring to FIG. 1, the MEMC method of the related art stores continuously input image data through a separate memory, analyzes a motion vector between a current frame and a next frame, And generates a new image or a black image. Thereafter, it is most widely used as a method of improving motion blur by inserting a new image or a black image generated between a current frame and a next frame.

Referring to FIG. 2, a conventional scanning backlight method sequentially turns on / off a plurality of lamps CCFL included in a backlight unit while maintaining a data frame of an image, The same effect as inserting a black image between the image and the image of the next frame improves motion blur.

Referring to FIG. 3, the GFI method of the related art increases the input image frame by a factor of two, and inputs one frame into two of a dark image frame (1/2 frame) and a bright image frame (1/2 frame) . Then, the divided two frames are sequentially displayed to reduce the motion blur.

However, the MEMC method requires complicated operations such as vector analysis to generate a new image to be inserted between the current frame image and the next frame image, and a separate operation for storing the current frame image and the next frame image A memory is required. Therefore, there is a problem that the cost is increased for the implementation. In addition, since the main frequency is doubled, heat generation during driving is increased, the charging time of the liquid crystal panel must be accelerated, and a liquid crystal having a high liquid crystal speed must be used.

The scanning backlight method sequentially turns on / off the light source CCFL of the backlight unit to obtain an effect of inserting a black image. In order to solve the problem of luminance reduction, the light source may be additionally disposed in the backlight unit, but other problems may occur in which the cost of the light source increases.

The GFI method can be easily applied because it has low complexity in implementation compared with the MEMC and scanning backlight methods for improving motion blur. However, since the main frequency is doubled as in the MEMC method, heat generation is increased, It is necessary to use a liquid crystal having a high liquid crystal speed. In addition, since one frame is divided into two to generate a bright image of one frame and dark image data of one frame, a large number of memories are required because the generated image data must be stored, and a high-performance device according to high frequency driving is applied The cost is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving apparatus and a driving method of a liquid crystal display which can improve display quality by driving light emitting diodes of a backlight unit block by block.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving apparatus and a driving method of a liquid crystal display capable of preventing a motion blur phenomenon occurring in a liquid crystal display device without lowering the luminance.

SUMMARY OF THE INVENTION The present invention provides a driving apparatus and a driving method of a liquid crystal display device capable of preventing a motion blur phenomenon generated in a liquid crystal display device without increasing the logic and cost in high speed image processing .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving apparatus and a driving method of a liquid crystal display which can improve the contrast ratio of an image displayed on a liquid crystal panel by driving light emitting diodes of a backlight unit on a block- .

According to an aspect of the present invention, there is provided a driving apparatus for a liquid crystal display, including: a timing controller for aligning input video signals into video data in units of frames; A data analyzer for analyzing the image data of one frame and setting an LED block so that a plurality of LEDs are driven in the same number of units based on the analysis result of the image data; A dimming value calculating unit for calculating a dimming value of the LED block corresponding to the one frame image data based on the analysis result of the image data and the LED block setting; A dimming value divider dividing the dimming value of the LED block corresponding to the one frame image data into dimming values of LED blocks corresponding to two frames; And an LED driver driving the LED block using a dimming value of the LED block corresponding to the two frames.

The dimming value divider divides the dimming value of the LED block corresponding to the one frame image data by the dimming value of the LED block of the first frame for displaying the bright image, And a dimming value of an LED block of a second frame for displaying a dark image.

According to another aspect of the present invention, there is provided a method of driving a driving apparatus for a liquid crystal display, the method comprising: setting an LED block such that a plurality of LEDs are driven in units of a predetermined number based on an analysis result of one frame of image data; Calculating a dimming value of the LED block corresponding to the one frame image data based on the analysis result of the image data and the LED block setting; Dividing a dimming value of an LED block corresponding to the one frame image data into dimming values of LED blocks corresponding to two frames; And driving the LED block using a dimming value of the LED block corresponding to the two frames.

The present invention can improve the display quality of the liquid crystal display by driving the light emitting diode of the backlight unit in units of blocks.

The present invention can prevent a motion blur phenomenon occurring in a liquid crystal display device without lowering the brightness.

The present invention can prevent a motion blur phenomenon occurring in a liquid crystal display device without increasing the logic and increasing the cost due to the high-speed image processing.

The embodiments of the present invention can improve the contrast ratio of an image displayed on the liquid crystal panel by driving the light emitting diodes of the backlight unit block by block.

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

FIG. 4 is a view illustrating a driving apparatus of a liquid crystal display according to an embodiment of the present invention, and FIG. 5 is a diagram specifically showing the driving apparatus shown in FIG. FIG. 4 schematically shows a liquid crystal display device including a driving device for a liquid crystal display device.

4 and 5, a driving apparatus for a liquid crystal display according to an exemplary embodiment of the present invention includes a timing controller 110, a block dimming control unit 140, and an LED control unit 150. The liquid crystal display device including the driving device of the liquid crystal display device includes a liquid crystal panel 120, a data driving circuit portion 112, a gate driving circuit portion 114 and a backlight unit 130.

The backlight unit 130 includes a plurality of LEDs 135 for generating light to be irradiated to the liquid crystal panel 120 and a plurality of LEDs 135 disposed on the plurality of LEDs 135, (Not shown) for guiding the light toward the liquid crystal panel 120 and improving the light efficiency.

The optical member includes a diffusion plate for uniformly irradiating the light generated from the LED 135 over the entire surface of the liquid crystal panel 120, a prism sheet for enhancing light efficiency by condensing the light emitted from the diffusion plate, And a polarizing sheet for polarizing light generated from the polarizing sheet.

The plurality of LEDs 135 used as the light source of the backlight unit 130 include a red LED for generating red light, a green LED for generating green light, a blue LED for generating blue light, and a white LED for generating white light can do. The plurality of LEDs 135 may be mounted on an array substrate, and the substrate may be formed of a metal material including a metal material having high thermal conductivity so as to dissipate heat generated from the LEDs 135 And may be a printed circuit board (PCB).

Each of the plurality of LEDs 135 is turned on via a driving power supply line provided on the substrate and a driving power supplied from a ground line. At this time, the plurality of LEDs 135 are controlled according to the control of the LED driving unit 150 And is irradiated to the liquid crystal panel 120 with light.

The liquid crystal panel 120 includes a thin film transistor (FTF) (not shown) formed for each pixel region P defined by a plurality of data lines DL and a plurality of gate lines GL, and a liquid crystal capacitor (Not shown) and a storage capacitor (not shown).

The liquid crystal capacitor is composed of a pixel electrode connected to the thin film transistor and a common electrode facing the pixel electrode with the liquid crystal therebetween. At this time, the pixel electrodes may be formed at regular intervals so as to have at least one bent portion or a flat shape. The thin film transistor supplies a data voltage from each data line DL to the pixel electrode in response to a gate voltage from each gate line GL. The liquid crystal capacitor realizes a desired image by charging the difference voltage between the data voltage supplied to the pixel electrode and the common voltage supplied to the common electrode, and adjusting the light transmittance of the liquid crystal according to the difference voltage.

The storage capacitor holds the voltage charged in the liquid crystal capacitor until the next data voltage is supplied. The storage capacitor may be formed by overlapping the pixel electrode and the previous gate line, or may be formed by overlapping the pixel electrode and the storage line, May be formed by overlapping electrode lines.

The data driving circuit unit 112 latches the data signals R, G, and B input from the timing controller 110 and outputs the latched data signals to the positive / negative analog And then generates a data voltage having a polarity corresponding to the polarity control signal and supplies the data voltage to the data lines DL.

To this end, the data driving circuit unit 112 may include a plurality of data driver integrated circuits including a shift register, a latch, a digital-analog converter, and an output buffer (not shown).

The gate driving circuit 114 generates a gate voltage in accordance with the gate control signal GCS from the timing controller 110 and sequentially supplies the generated gate voltage to the gate lines GL. At this time, the gate driving circuit 114 may include a plurality of gate driver integrated circuits including a level shifter for converting the output signals of the shift register and the shift register into a swing width suitable for driving the thin film transistor. The gate driving circuit portion 114 may be formed on the substrate simultaneously with the formation of the thin film transistor.

The driving apparatus of the liquid crystal display according to the embodiment of the present invention aligns the image signals R, G, and B input from the outside to generate image data R, G, and B for each frame, Analyze the data. Thereafter, the plurality of LEDs formed in the backlight unit are driven block by block according to the analysis result of the image data, thereby preventing the motion blurring phenomenon occurring in the liquid crystal display device.

6, in the case where an image of one frame is to be displayed on the liquid crystal panel 120, the driving apparatus of the liquid crystal display of the present invention analyzes image data of one frame, And the LED blocks A, B, C, and D constituted by a certain number of LEDs 135 are formed by using the calculated luminance values, Setting.

The original frame is divided into two frames: a first frame for displaying a bright image and a second frame for displaying a dark image. Each LED block is divided into a first frame having a high luminance value (displaying a bright image) , And a second frame having a low luminance value (displaying a dark image), and drives it in a local dimming manner. At this time, the average value of the dimming values of the two frames divided in one original frame has the same dimming value as that of the original frame.

To this end, a driving apparatus for a liquid crystal display according to an embodiment of the present invention includes a timing controller 110, a block dimming control unit 140, and an LED driving unit 150. Hereinafter, a driving apparatus and a driving method of a liquid crystal display according to an embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG.

The timing controller 110 of the driving apparatus for a liquid crystal display according to an embodiment of the present invention aligns the input video signals R, G, and B so as to be suitable for driving the liquid crystal panel 120, R, G, and B to the data driving circuit unit 112 and the block dimming control unit 140 (S10). Here, the image data may include individual gray levels corresponding to the pixel voltages to be applied to the pixel electrodes of the red, green, and blue pixels of the liquid crystal panel 120.

The timing controller 110 controls the timing of the data driving circuit unit 112, the gate driving circuit unit 114 and the block dimming control unit 140 using the input timing synchronization signal TSS. Signals.

Here, the timing synchronization signal TSS is a vertical synchronization signal Vsync; A horizontal synchronizing signal Hsync; A data enable signal (Data Enable); And a dot clock (DCLK).

The timing control signals are supplied to a data control signal DCS for supplying a data voltage to the data line DL of the liquid crystal panel 120 and a gate control signal GCS for driving the gate line GL of the liquid crystal panel 120. [ ). ≪ / RTI >

Here, the data control signal DCS may be a source start pulse, a source sampling clock, a source output enable signal, and a polarity control signal (Polarity). The gate control signal GCS may be a gate start pulse, a gate shift clock, a gate output enable signal, or the like.

5, the block dimming control unit 140 of the driving apparatus for a liquid crystal display according to an embodiment of the present invention includes a data analysis unit 142 and a dimming value calculation unit 144, 150 includes a dimming value divider 152 and an LED driver 154.

The data analyzing unit 142 of the block dimming control unit 140 analyzes the image data input in units of frames input from the timing controller 110 and outputs the luminance value corresponding to each of the plurality of LEDs 135 to the backlight unit 130 (S20).

Then, the number of LED blocks is set based on the analysis result of the image data, that is, the luminance value corresponding to each of the plurality of LEDs 135. [ To this end, the plurality of LEDs 135 are grouped in units of a predetermined number so that a plurality of LEDs 135 formed in the backlight unit 130 can be driven in units of LED blocks (S30).

Here, the LED block is generated based on the detected luminance value. As shown in FIG. 8, a predetermined number of LEDs having the same luminance value, for example, a luminance value of "50 " The LEDs 135 may be grouped into a single LED group.

In addition, the LEDs 135 can be set by grouping a certain number of LEDs 135 having a luminance value of a certain range among all the LEDs 135 into one group.

For example, when a plurality of LEDs 135 are driven with a luminance value of 0 to 255, a predetermined number of luminance values having luminance values of a certain range such as luminance values of 0 to 15, ..., and luminance values of 240 to 255 The LEDs 135 may be grouped into one group to set the LED blocks.

Here, the LED blocks may be set to the same number as the total number of LEDs 135 constituting the maximum backlight unit from at least one LED 135, and the number of the LEDs 135 constituting each LED block may be the same Can be different.

The dimming value calculating unit 144 of the block dimming control unit 140 calculates the dimming value of each of the LED blocks corresponding to the video data of one frame based on the analysis result of the video data from the data analyzing unit 142 and the LED block setting (S40). At this time, the dimming value for each LED block can be set reflecting the weight according to the luminance interference (backlight effect) between adjacent LED blocks.

The dimming value division unit 152 of the LED control unit 150 divides one frame into two frames and stores the dimming value of each frame of the one frame supplied from the dimming value calculation unit 144 for each LED block of two frames (S50). Here, each of the two divided frames may have a period corresponding to 1/2 (t) of the original one frame.

For example, the dimming value division unit 152 may include a first frame for displaying one frame of a bright image and a second frame for displaying a dark image, that is, a first frame for displaying a high luminance (bright image) (Dark image) is displayed.

Then, the dimming value for each LED block from the dimming value calculating unit 144 is divided so as to correspond to each of the two divided first and second frames. At this time, the average value of the dimming values of the LED blocks of the two frames divided in the original one frame has the same value as the dimming value of the original one frame LED block. Then, a dimming value for each LED block, which is divided into the first frame and the second frame, is provided to the LED driver 154.

The LED driving unit 154 drives each LED block in the two frames in a local dimming manner based on the dimming value of each LED block divided into two frames from the dimming value dividing unit 152 (S60).

For example, when a period of one frame is 1T and a plurality of LEDs 135 are divided into 12 LED blocks and driven, 12 LED blocks are driven at high luminance for 1 / 2t corresponding to the divided first frame And displays a dark image by driving the twelve LED blocks at a low luminance for 1 / 2t corresponding to the remaining second frame.

As a result, twenty-four LED blocks corresponding to twice the actually set 12 LED blocks are locally driven according to the set dimming value. Accordingly, the number of locally driven LED blocks is increased and the driving frame is doubled without changing the input actual image data, thereby improving the display quality of the liquid crystal display device.

A driving apparatus and a driving method of a liquid crystal display according to an embodiment of the present invention can be realized by driving light emitting diodes of a backlight unit block by block so that the luminance of the liquid crystal display It is possible to prevent the motion blur phenomenon and improve the display quality. In addition, it is possible to prevent a light phenomenon that may occur at low grayscale values, thereby improving the contrast ratio of the image displayed on the liquid crystal panel.

It will be understood by those skilled in the art that the present invention may 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.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a prior art MEMC method for improving motion blurring phenomenon of a liquid crystal display device. Fig.

2 is a diagram showing a prior art scanning backlight method for improving motion blurring phenomenon of a liquid crystal display device.

3 is a diagram showing a conventional GIF (Gray Field Insertion) method for improving the motion blur phenomenon of a liquid crystal display device.

4 is a view illustrating a driving apparatus for a liquid crystal display according to an embodiment of the present invention.

5 is a diagram specifically showing the drive device shown in Fig.

6 and 7 are views showing a driving method of a driving apparatus of a liquid crystal display according to an embodiment of the present invention.

8 is a diagram showing a setting method of an LED block;

Description of the Related Art [0002]

110: timing controller 112: data driving circuit

114: gate driving circuit part 120: liquid crystal panel

130: Backlight unit 135: LED

140: block dimming control unit 142:

144: dimming value calculating unit 150: LED control unit

152: dimming value division unit 154: LED driving unit

Claims (10)

A timing controller for aligning input video signals into video data of one frame unit; A data analyzer for analyzing the image data of one frame and setting an LED block so that a plurality of LEDs are driven in the same number of units based on the analysis result of the image data; A dimming value calculating unit for calculating a dimming value of the LED block corresponding to the one frame image data based on the analysis result of the image data and the LED block setting; A dimming value dividing unit dividing the one frame into two frames and dividing the dimming value of the LED block corresponding to the one frame image data into the dimming values of the LED blocks corresponding to the two frames; And And an LED driver driving the LED block using a dimming value of the LED block corresponding to the two frames. The apparatus of claim 1, wherein the data analysis unit And calculates a luminance value corresponding to each of the plurality of LEDs based on an analysis result of the image data. The apparatus of claim 1, wherein the dimming value calculator And the dimming value of the LED block is calculated by reflecting the weight according to the luminance interference between adjacent LED blocks. The LED module according to claim 1, wherein the LED block And a predetermined number of LEDs having the same luminance and / or a predetermined number of LEDs having a luminance value of a certain range. 2. The apparatus of claim 1, wherein the dimming value divider The dimming value of the LED block corresponding to the one frame image data is divided into the dimming value of the LED block of the first frame for displaying the bright image and the dimming value of the LED block of the second frame for displaying the dark image. And a driving circuit for driving the liquid crystal display device. The method according to claim 1, Wherein the average value of the dimming values of the LED blocks corresponding to the two frames has the same value as the dimming value of the LED block corresponding to the one frame image data. Setting an LED block so that a plurality of LEDs are driven in the same number of units based on an analysis result of one frame of image data; Calculating a dimming value of the LED block corresponding to the one frame image data based on the analysis result of the image data and the LED block setting; Dividing one frame into two frames and dividing the dimming value of the LED block corresponding to the one frame image data into dimming values of the LED blocks corresponding to the two frames; And And driving the LED block using a dimming value of the LED block corresponding to the two frames. 8. The method of claim 7, wherein in the step of setting the LED block, And calculating a luminance value corresponding to each of the plurality of LEDs based on an analysis result of the image data. 8. The method according to claim 7, wherein in the step of calculating the dimming value of the LED block, Wherein the dimming value of the LED block is calculated by reflecting a weight according to luminance interference between adjacent LED blocks. 8. The method of claim 7, wherein the dimming values of the LED blocks corresponding to the two frames, A dimming value of the LED block of the first frame for displaying a bright image, And the second frame is a dimming value of an LED block of a second frame which displays a dark image.

Images