KR20080018049A - Motion blur improvement apparatus for liquid crystal display - Google Patents

Abstract

An apparatus for obviating motion blur of an LCD is provided to add a TFT(Thin Film Transistor) array and a liquid crystal cell and block a backlight light source by each gate line unit by using a separate gate driver and data driver, thereby improving a scanning backlight function and providing a clear image. A TFT array and a liquid crystal cell layer(65B) are installed between a liquid crystal panel(65A) and a backlight of an LCD, and blocks light emitted from the backlight by each gate line unit of a predetermined ratio. A gate driver(63B) supplies a gate ON signal to the TFT array and the liquid crystal cell layer. A data driver(64B) alternately supplies a white data voltage and a black data voltage to data lines of the liquid crystal cell layer and the TFT array.

Description

Motion Blur Improvement Device for Liquid Crystal Display {MOTION BLUR IMPROVEMENT APPARATUS FOR LIQUID CRYSTAL DISPLAY}

1 is a block diagram of a liquid crystal display device according to the prior art.

2A is an explanatory diagram showing a principle in which an impulse driving method does not generate motion blur;

2B is an explanatory diagram showing a principle in which a hold type driving method generates motion blur;

3 is an exemplary black data display for improving a motion blur phenomenon.

4A and 4B are explanatory diagrams of a ghost generation principle of a liquid crystal display;

5 is a waveform diagram showing a driving principle of a scanning backlight according to the prior art.

6 is a block diagram of an apparatus for improving motion blur of a liquid crystal display according to the present invention.

7 is a waveform diagram showing a principle of precisely controlling the light source of the backlight for each gate line using a TFT array according to the present invention;

8 (a)-(c) are waveform diagrams of signals for precisely controlling the light source of the backlight for each gate line;

*** Description of the symbols for the main parts of the drawings ***

61: system 62: timing controller

63A: first gate driver 63B: second gate driver

64A: first data driver 64B: second data driver

65A: liquid crystal panel 65B: TFT array and liquid crystal cell layer

66: DC / DC converter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving a motion-blur phenomenon in a liquid crystal display device. In particular, a TFT array and a liquid crystal cell are added to a liquid crystal panel, and light sources are sequentially sequenced by using a predetermined block unit. The present invention relates to a motion blur improving device of a liquid crystal display device which is suitable for blocking motion blur to improve a motion blur phenomenon.

In general, liquid crystal display (LCD) has a trend that the application range is gradually expanded to office automation equipment, audio / video equipment, etc. due to features such as light weight, thin, low power consumption.

1 is a block diagram of a liquid crystal display device according to the prior art, as shown therein, a liquid crystal panel 15 driven by a data signal and a gate-on signal to display an image; A gate driver 13 supplying a gate-on signal to each gate line of the liquid crystal panel 15; A data driver 14 for supplying the data signal to each data line of the liquid crystal panel 15; A timing controller 12 outputting a control signal for controlling the driving of the gate driver 13 and the data driver 14; The DC / DC converter 16 for generating various driving voltages required by the liquid crystal panel 15 is included, and the operation of the conventional liquid crystal display device configured as described above is as follows.

The liquid crystal panel 15 includes a plurality of liquid crystal cells Clc arranged in a matrix at the intersection of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc transfers a data voltage input from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Clc, which is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or between the pixel electrode and the common electrode of the liquid crystal cell Clc. It is formed to maintain a constant voltage of the liquid crystal cell (Clc).

The graphics processing circuit of the system 11 converts analog data into digital video data RGB and adjusts the resolution and color temperature of the digital video data RGB. The digital video data RGB and the vertical / horizontal synchronization signal and the clock signal output from the system 11 are supplied to the timing controller 12.

The timing controller 12 controls the gate control signal GDC and the data driver 14 for controlling the gate driver 13 using the vertical / horizontal synchronization signal and the clock signal supplied from the system 11. To generate a data control signal DDC. In addition, the timing controller 12 samples the digital video data RGB input from the system 11 and rearranges the same, and supplies the data to the data driver 14.

The data driver 14 converts the digital video data RGB into a data voltage (analog gamma compensation voltage) corresponding to the gray scale value in response to the data control signal DDC from the timing controller 12. The data voltage is supplied to the data lines D1 to Dm on the liquid crystal panel 15.

The gate driver 13 sequentially supplies scan pulses (gate pulses) to the gate lines G1 to Gn in response to a gate control signal GDC from the timing controller 12 to supply data. Select the horizontal lines in 15).

For reference, in the above description, the data driver 14 and the gate driver 13 are separately installed from the liquid crystal panel 15. However, in recent years, the chip on glass (COG) and the chip on film or chip (COF) have been installed. Packaging technology of On Flexible Printed Circuit is used.

The COG is a packaging technology in which a flip chip cut by a wafer is directly mounted on a glass substrate, unlike a liquid crystal panel and a packaged LDI mounted in a TAB method when manufacturing a flat panel display. In other words, COG is a packaging method that enables the LDI controlling the pixels of the LCD to be bonded directly onto the glass panel to enable fine pitch, ultra-thin, and light weight.

In addition, the COF is a packaging method in which the chip is integratedly mounted on a thin film-type circuit board capable of directly attaching a semiconductor chip, and may use a thinner film than a conventional TCP (TCP: Tape Carrier Package). It is also a packaging method that can be designed more densely.

The DC / DC converter 16 generates a high potential common voltage VDD voltage, VCOM voltage, gate on (or high) voltage VGH, and gate off (or low) voltage VGL using the VCC voltage from the system 11. do.

On the other hand, an image display device such as CRT displays an image by an impulse driving method, so motion blur does not occur. However, a liquid crystal display device uses a hold type driving method using a storage capacitor. .

2A is an explanatory diagram illustrating a principle in which motion blur is not generated when an image is displayed by the impulse driving method. On the other hand, in the case of a liquid crystal display device displaying an image by the hold-type driving method, the response speed of the liquid crystal is slower than one frame, resulting in motion blur, which makes it impossible to clearly display an image. It is explanatory drawing which showed the generation principle of.

Therefore, in the conventional liquid crystal display, as a part of improving the motion blur phenomenon, black data is inserted into each image frame so that horizontal black bands are sequentially displayed while moving in the vertical direction. 3 shows an example of such a display.

That is, 70% of the original image is displayed on the horizontal line of one frame and black data is displayed on the other 30%. The insertion position of the black data is sequentially moved every frame in the vertical direction. By doing so, the charge charge of the storage capacitor Cst is discharged for each block of the image frame, thereby improving the motion blur phenomenon, which is a disadvantage of the hold type.

As another method for improving the motion blur, there is a scanning backlight method that sequentially turns on / off lamps in a liquid crystal display device employing a direct type lamp.

4 illustrates a principle of ghost generation in a liquid crystal display. That is, when the backlight lamp is turned on in the pixel-on area as shown in FIG. 4A, the ghost phenomenon does not occur. However, when the lamp is turned on in the area outside the pixel-on area as shown in FIG. 4B, the ghost phenomenon appears on the screen. .

A liquid crystal display having a resolution of 1366 * 768 has 768 gate output lines, whereas a backlight lamp (eg, HCFL) typically employs 24. Accordingly, the gate output line may be controlled block by block to perform the scanning backlight function, but not line by line. 5 illustrates a driving principle of a conventional scanning backlight that controls the gate output line block by block as described above. Accordingly, the backlight on time at the first gate output line is different from the backlight on time at the last gate output line.

As a result, in the conventional liquid crystal display device, it is difficult to precisely control the scanning backlight function. For this reason, there is a defect that a ghost image is generated due to a side effect.

Accordingly, an object of the present invention is to provide a motion blur improving apparatus for adding a TFT array and a liquid crystal cell between a liquid crystal panel and a backlight and using the same to block the backlight light source for each gate line.

The present invention for achieving the above object is a liquid crystal panel which is driven by a data signal and a gate-on signal to display an image; A TFT array and a liquid crystal cell layer disposed between the liquid crystal panel and the backlight to block light emitted from the backlight by a gate line at a predetermined ratio; A gate driver supplying a gate-on signal to each gate line of the TFT array and the liquid crystal cell layer; A data driver to alternately supply a white data voltage and a black data voltage to data lines of the TFT array and the liquid crystal cell layer within a predetermined period; And a timing controller for outputting various control signals for controlling the driving of the liquid crystal panel.

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

FIG. 6 is a block diagram showing an embodiment of an apparatus for improving motion blur of a liquid crystal display according to the present invention. As shown therein, a liquid crystal panel 65A driven by a data signal and a gate-on signal to display an image is shown. and; A TFT array and a liquid crystal cell layer (65B) disposed between the liquid crystal panel (65A) and a backlight to block light irradiated from the backlight by a predetermined ratio of gate line units; A first gate driver 63A for supplying a gate-on signal to each gate line of the liquid crystal panel 65A; A second gate driver 63B for supplying a gate-on signal to each gate line of the TFT array and the liquid crystal cell layer 65B; A first data driver 64A for supplying the data signal to each data line of the liquid crystal panel 65A; A second data driver 64B which alternately supplies a white data voltage and a black data voltage to the data lines of the TFT array and the liquid crystal cell layer 65B within a predetermined period; A timing controller 62 for outputting a control signal for controlling the driving of the first gate driver 63A and the first data driver 64A; A DC / DC converter 66 for generating various driving voltages required by the liquid crystal panel 65A is included. The operation of the present invention configured as described above will be described in detail with reference to FIG. 6. same.

The process of displaying an image by controlling the driving of the liquid crystal panel 65A through the first gate driver 63A and the first data driver 64A is the same as in a conventional liquid crystal display device.

That is, the liquid crystal panel 65A includes a plurality of liquid crystal cells Clc arranged in a matrix at the intersection of the data lines D1 to Dm and the gate lines G1 to Gn. Each TFT formed in the liquid crystal cell Clc transfers a data voltage input from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied from the gate line G. In addition, a storage capacitor Cst is formed in each of the liquid crystal cells Clc, which is formed between the pixel electrode of the liquid crystal cell Clc and the front gate line, or between the pixel electrode and the common electrode of the liquid crystal cell Clc. It is formed to maintain a constant voltage of the liquid crystal cell (Clc).

The graphics processing circuit of the system 61 converts analog data into digital video data RGB and adjusts the resolution and color temperature of the digital video data RGB. The digital video data RGB and the vertical / horizontal synchronization signal and the clock signal output from the system 61 are supplied to the timing controller 62.

The timing controller 62 may include a gate control signal GDC and a first data driver 64A for controlling the first gate driver 63A using a vertical / horizontal synchronization signal and a clock signal supplied from the system 61. ) Generates a data control signal (DDC) for controlling. In addition, the timing controller 62 samples the digital video data RGB input from the system 61 and rearranges the digital video data RGB to be supplied to the first data driver 64A.

The first data driver 64A converts the digital video data RGB into a data voltage (analog gamma compensation voltage) corresponding to the gray scale value in response to the data control signal DDC from the timing controller 62. The data voltage thus converted is supplied to the data lines D1 to Dm on the liquid crystal panel 65A.

The first gate driver 63A sequentially supplies scan pulses (gate pulses) to the gate lines G1 to Gn in response to the gate control signal GDC from the timing controller 62 to supply data. Select the horizontal lines of panel 65A.

For reference, in the above description, the first data driver 64A and the first gate driver 63A are separately installed from the liquid crystal panel 65A. However, in recent years, each of the first data driver 64A and the first gate driver 63A is installed on a chip on glass (COG) or a COF (COG). COF: Chip On Film or Chip On Flexible Printed Circuit (CFT) is being installed in liquid crystal panels.

The DC / DC converter 66 generates the high potential common voltage VDD voltage, VCOM voltage, gate on (or high) voltage VGH, and gate off (or low) voltage VGL using the VCC voltage from the system 61. do.

In the present invention, the TFT array and the liquid crystal cell layer 65B are further provided between the liquid crystal panel 65A and the backlight, and the TFT array and the liquid crystal cell layer 65B are formed by using the second gate driver 63B. By appropriately controlling the driving of the gate line, the light source projected from the backlight to the liquid crystal panel 65A side is sequentially blocked at a predetermined ratio (for example, 30%), thereby enabling more precise light source control, thereby allowing a ghost image. Is prevented from occurring and the motion blur phenomenon is improved.

To this end, a liquid crystal having a response time (5 ms) that is the same as that of a hot cathode fluorescent lamp (HCFL) is employed, and a second second data driver 64B is used to supply a data voltage to the TFT array and the liquid crystal cell layer 65B. ).

The first data driver 64A supplies a data voltage of 15V to the liquid crystal panel 65A, but the second data driver 64B supplies 18 to 20V of white data to the TFT array and the liquid crystal cell layer 65B. The black data voltage (for example, 6V) of the voltage and the common voltage (Vcom) level is supplied at a timing described later. The reason for supplying such a high data voltage (18-20V) is to obtain fast response characteristics of the liquid crystal.

FIG. 7 is a waveform diagram illustrating a principle of precisely blocking a light source of a backlight by controlling each gate line by using the TFT array and the liquid crystal cell layer 65B. That is, as compared with FIG. 5, it can be seen that each HCFL lamp response is enabled in response to the response time of each pixel.

8 is a timing diagram illustrating output timings of the data voltage and the black data voltage in the second data driver 64B. That is, the second data driver 64B counts the source out enable signal SOE provided from the timing controller 62 to generate a clock signal as shown in FIG. A gate enable signal GOE is generated as shown in (b) of FIG.

When the first (odd) gate enable signal GOE is output, the white data voltage of 18 to 20V is applied to the data lines D1 'to Dm' of the TFT array and the liquid crystal cell layer 65B. When the second (even) gate enable signal GOE is outputted, a black data voltage (eg, 6V) having a common voltage Vcom level is supplied.

Accordingly, the gate lines G1 'to Gn' of the TFT array and the liquid crystal cell layer 65B are sequentially driven by the second gate driver 63B so that the TFTs connected to the corresponding gate lines are turned on when the TFTs connected to the corresponding gate lines are turned on. The charging voltage of the storage capacitor is discharged to the common voltage Vcom level so that the liquid crystal displays black, thereby blocking the backlight light source of the pixel on the liquid crystal panel 65A.

Accordingly, among the gate lines of the TFT array and the liquid crystal cell layer 65B, the liquid crystal cells connected to the gate line corresponding to a predetermined ratio (for example, 30%) sequentially display black, whereby the light source of the corresponding region is displayed. Since it is sequentially blocked, it is possible to more accurately block the backlight light source.

Of course, when the liquid crystal cells connected to the gate line corresponding to a predetermined ratio (for example, 30%) of the entire gate lines block the light source by displaying black, 70% of the liquid crystal cells except for these are white data voltages of 18 to 20V. It is driven by the light source is irradiated from the backlight passes through the upper liquid crystal panel 65A side.

As described in detail above, in the present invention, by adding a TFT array and a liquid crystal cell to the liquid crystal panel and using a separate gate driver and a data driver to block the backlight light source for each gate line, the scanning backlight function is greatly improved. As a result, a clear image can be provided.

Claims (8)

A TFT array and a liquid crystal cell layer disposed between the liquid crystal panel of the liquid crystal display device and the backlight, the TFT array and a liquid crystal cell layer blocking light emitted from the backlight by a predetermined ratio of gate lines; A gate driver supplying a gate-on signal to the TFT array and the liquid crystal cell layer; And a data driver configured to alternately supply a white data voltage and a black data voltage to the data array of the TFT array and the liquid crystal cell layer within a predetermined period. The liquid crystal display device of claim 1, wherein the TFT array and the liquid crystal cell layer are configured to block 30% of light from the light emitted from the backlight based on a gate line and to pass the remaining 70% of light. Motion blur improvement device. The TFT array and the liquid crystal cell layer of claim 1, wherein when the TFT connected to the gate line driven by the gate driver is turned on, the charging voltage of the storage capacitor connected to the TFT is discharged to a black data voltage level so that the liquid crystal is black. Motion blur improvement device of the liquid crystal display device, characterized in that configured to display. 4. The apparatus of claim 3, wherein the black data voltage is a common voltage. The TFT array and the liquid crystal cell layer of claim 1, wherein the liquid crystal cells connected to the gate line corresponding to 30% of the total gate lines display black to block the light source, and the remaining 70% of the liquid crystal cells are controlled by the white data voltage. And a light source for driving the light source irradiated from the backlight to the liquid crystal panel. The data driver of claim 1, wherein the data driver generates a clock signal by counting the source out enable signal, generates a gate enable signal using the same, and outputs a white data voltage at an odd period thereof, and generates an even period. And a black data voltage at the motion blur improving device of the liquid crystal display device. 7. The apparatus of claim 6, wherein the odd period is 6 ms and the even period is 8 ms. 7. The motion blur improving apparatus of claim 6, wherein the white data voltage is 18 to 20V.

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