KR101502163B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device capable of improving display quality is disclosed.

The liquid crystal display of the present invention includes a liquid crystal display panel, an image extracting unit for analyzing a data signal supplied to the liquid crystal display panel to detect a local motion blur phenomenon of the liquid crystal display panel, And a backlight unit having an off interval so as to be synchronized with a period in which local motion blur of the liquid crystal display panel detected by the image extracting unit occurs in response to the backlight control signal.

Motion, blur, sync, video, extract

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device capable of improving display quality.

2. Description of the Related Art In recent years, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes (CRTs), are emerging. Examples of such flat panel display devices include a liquid crystal display device, a field emission display device, a plasma display device, and an organic electro luminescence display device .

Among the display devices, a liquid crystal display device is a device that displays light by generating light from a light source on the rear side, by selectively transmitting each pixel of the liquid crystal display panel on the front side as a kind of optical switch. That is, while a conventional cathode ray tube (CRT) controls brightness by controlling the intensity of an electron beam, a liquid crystal display controls the intensity of light generated from a light source to display a screen.

The liquid crystal display device includes a liquid crystal display panel, a timing controller, and a gate and a data driver for driving the liquid crystal display panel using the timing signal supplied from the timing controller.

A liquid crystal display panel includes a plurality of gate lines for transmitting a scan signal, a plurality of data lines for transmitting image data intersecting the plurality of gate lines, a pixel defined by the gate lines and the data lines, And a thin film transistor formed in a crossing region of the gate lines and the data lines.

The liquid crystal display panel is composed of one frame when the image to be displayed is a still image, and a plurality of frames when the moving image is a plurality of sequential still images. When the image is a moving image, the liquid crystal layer of the liquid crystal display panel is continuously driven by the magnitude of a data signal corresponding to each frame.

The size of the data signal of each frame is expressed by the magnitude of the gradation voltage in the liquid crystal layer to change the direction of the liquid crystal molecules in the liquid crystal layer. Since the liquid crystal molecules have dielectric anisotropy, , The dielectric constant changes. The change in the dielectric constant causes the gradation voltage applied to the liquid crystal layer to change, and the response speed of the liquid crystal molecule in the liquid crystal layer remarkably drops due to the change in the gradation voltage.

That is, when the gradation voltage applied to the liquid crystal is changed from a low gradation voltage to a high gradation voltage, since the gradation voltage of the current frame data signal is affected by the gradation voltage of the previous frame data signal, The signal reaches the normal gradation voltage only after several frames have elapsed.

Such a phenomenon may be displayed as a residual image in which the image of the second frame on the liquid crystal display panel overlaps the image of the first frame of the previous time.

Recently, a method of improving the response speed of the liquid crystal molecules by over driving the data signal for setting the gray scale voltage to a value higher than the normal value is used.

However, since the general liquid crystal display device of the over-driving driving method compensates the image data based on the intermediate point of the liquid crystal display panel, there is a problem that it is difficult to compensate the entire liquid crystal display panel. That is, in general liquid crystal display devices, although over-driving driving or the like is used to improve motion blur in which after-images are seen, there is a problem that local motion blur generated at the upper or lower end of the liquid crystal display panel can not be improved .

An object of the present invention is to provide a liquid crystal display device capable of improving display quality.

According to an embodiment of the present invention,

A liquid crystal display panel: an image extracting unit for analyzing a data signal supplied to the liquid crystal display panel to detect a local motion blur phenomenon of the liquid crystal display panel; And a backlight unit having an off interval so as to be synchronized with a period in which local motion blur of the liquid crystal display panel is detected by the image extracting unit in response to the backlight control signal output from the image extracting unit .

The liquid crystal display device of the present invention is able to fundamentally improve the generation of motion blur by blocking light during a motion blur period occurring locally by stopping the driving of the backlight unit during a period in which motion blur occurs.

Accordingly, the present invention controls the backlight unit so as to have an off interval for extracting a motion blur period locally generated from the image extracting unit and turning off the driving of the backlight unit to synchronize with the motion blur period, thereby generating local motion blur Thereby improving the display quality of the liquid crystal display device.

In the present invention, a liquid crystal display device will be described as an example of a flat panel display device.

FIG. 1 is a view schematically showing a liquid crystal display according to an embodiment of the present invention, and FIG. 2 is a diagram showing the structure of an image extracting unit of the present invention.

1 and 2, a liquid crystal display according to an exemplary embodiment of the present invention includes a plurality of gate lines GL1 to GLn and data lines DL1 to DLm, A liquid crystal display panel 110 in which a thin film transistor (TFT) is formed for driving the liquid crystal display panel Clc, data for supplying a data signal to the data lines DL1 to DLm of the liquid crystal display panel 110, A gate driver 130 for supplying a scan signal to the gate lines GL1 to GLn of the liquid crystal display panel 110 and a gate driver 130 for controlling the gate driver 130 and the data driver 120 And a timing controller 150.

The liquid crystal display of the present invention includes an image extracting unit 160 for analyzing data signals Data R, G and B supplied from a timing controller 150 or an external system not shown, And a backlight unit 170 for providing light to the liquid crystal display panel 110 based on the analyzed image.

In the liquid crystal display panel 110, a thin film transistor (TFT) is formed as a switching element for each liquid crystal cell. The gate electrode of the thin film transistor TFT is connected to the gate lines GL1 to GLn, the source electrode thereof is connected to the data lines DL1 to DLm, the drain electrode thereof is connected to the pixel electrode of the liquid crystal cell Clc, (Cst). The common voltage Vcom is supplied to the common electrode of the liquid crystal cell Clc and the storage capacitor Cst charges the data voltage supplied from the data lines DL1 to DLm when the thin film transistor TFT is turned on Thereby maintaining the voltage of the liquid crystal cell Clc constant.

When the scan pulse is sequentially supplied to the gate lines GL1 to GLn, the thin film transistor TFT is turned on to form a channel between the source electrode and the drain electrode to supply the voltage on the data lines DL1 to DLm to the liquid crystal cell (Clc). At this time, the liquid crystal molecules of the liquid crystal cell Clc are changed in arrangement by the electric field between the pixel electrode and the common electrode to modulate the incident light.

The data driver 120 supplies a data signal to the data lines DL1 to DLm in response to the data driving control signal DCS supplied from the timing controller 150. [ The data driver 120 samples and latches the image data (Data R, G, and B) input from the timing controller 150 and then latches the image data (Data R, G, and B) on the liquid crystal display panel 110 ) Into an analog data voltage capable of expressing the gradation in the liquid crystal cell Clc of the liquid crystal cell Clc and supplies it to the data lines DL1 to DLm.

Here, the data driving control signal DCS supplied from the timing controller 150 includes SSP, SSC, SOE, POL, and the like.

The gate driver 130 sequentially generates scan pulses in response to a gate drive control signal GCS supplied from the timing controller 150 and sequentially applies scan pulses to the gate lines GL1 to GLn sequentially .

Here, the gate drive control signal (GCS) supplied from the timing controller 150 includes GSP, GSC, GOE, and the like.

The timing controller 150 uses the vertical / horizontal synchronizing signal Vsync / Hsync, the data enable signal DE, the clock signal clk and the data signals Data R, G and B supplied from the system 100 And controls the data driver 120 and the gate driver 130.

The image extracting unit 160 analyzes the image data using the vertical and horizontal synchronizing signals Vsync / Hsync of the data signals (Data R, G, B) input from the timing controller 150 and outputs local motion blur blur is generated.

The R, G and B data signals of the current frame and the R, G and B data signals of the current frame are stored in the frame memory 161, And a data comparator 163 for comparing the data signals and extracting an interval in which the R, G, and B data signals of the previous frame and the R, G, and B data signals of the current frame are large.

A vertical / horizontal synchronizing signal (Vsync / Hsync) is input to the data comparator 163 to extract a period in which the R, G, and B data signals of the previous frame and the R, G, and B data signals of the current frame are large. can do.

The data comparator 163 extracts a motion blur period that occurs locally and outputs a backlight control signal BL-CS for controlling the backlight unit 170 to the backlight control unit of the backlight unit 170 (Not shown).

The backlight control signal BL-CS output from the image extracting unit 160 is a control signal related to a motion blur period occurring locally and is a control signal for extracting the motion blur period based on the horizontal interval of the liquid crystal display panel 110 Control signal. For example, when the analyzed motion blur period from the image extracting unit 160 is from the first horizontal line to the third horizontal line of the liquid crystal display panel 110, the image extracting unit 160 extracts the first horizontal (BL-CS) for turning off the backlight unit 170 during a period in which the data signal is supplied from the first horizontal line to the third horizontal line to the backlight unit 170.

Here, the image extracting unit 160 compares the R, G, and B data signals of the previous frame with the R, G, and B data signals of the current frame to detect the motion blur occurrence period, and outputs the vertical / / Hsync) to detect the final motion blur occurrence period.

In addition, the image extracting unit 160 detects a motion blur period based on one frame.

The backlight unit 170 has an off period synchronized with a motion blur period generated locally by the backlight control signal (BL-CS) from the image extracting unit 160.

The backlight unit 170 according to an exemplary embodiment of the present invention extracts a motion blur period locally generated from the image extracting unit 160 and outputs an off-period for turning off the driving of the backlight unit 170 to be synchronized with the motion blur period By controlling the backlight unit 170 so as to have the local motion blur.

Therefore, in the present invention, in all areas of the liquid crystal display device, the motion blur period is detected at the image extracting unit 160 at the time of motion blur occurrence and the backlight unit 170 is controlled to be synchronized during the detected motion blur period, The local motion blur occurrence of the display device can be improved. Here, the liquid crystal display device of the present invention detects the occurrence of motion blur from time to time, and the result of the detection (the motion blur period) is varied, thereby varying the row interval of the backlight unit 170 accordingly.

3 is a waveform diagram showing on / off driving signals of a backlight unit according to an image analyzed by the image extracting unit of the present invention.

Referring to FIG. 3, a case where local motion blur occurs in a lower region of the liquid crystal display panel will be described as an example.

As shown in FIG. 3, the backlight unit of the present invention has an off-period (a) during a motion blur occurrence period.

The motion blur generation period of one example is formed by connecting pixels connected to the n-2th gate line GLn-2 of the liquid crystal display panel, pixels connected to the (n-1) th gate line GLn-1, ), ≪ / RTI >

The on / off signal (BL signal) of the backlight unit is applied to the pixels connected to the (n-2) th gate line GLn-2, the pixels connected to the (n-1) (A) so as to be synchronized with the high period in which the data signal is supplied to the pixels connected to the scan lines GLn.

That is, by stopping the driving of the backlight unit during a period in which motion blur occurs, the present invention can fundamentally improve the generation of motion blur by blocking light during a motion blur period occurring locally.

As described above, according to the present invention, the backlight unit is controlled so as to have an off-period for extracting a motion blur period locally generated from the image extracting unit and turning off the driving of the backlight unit to be synchronized with the motion blur period, The occurrence of motion blur can be improved and the display quality of the liquid crystal display device can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

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

2 is a diagram showing a structure of an image extracting unit of the present invention.

3 is a waveform diagram showing on / off driving signals of a backlight unit according to an image analyzed by the image extracting unit of the present invention.

Claims (5)

Liquid crystal display panel: An image extracting unit for detecting a local motion blur phenomenon of the liquid crystal display panel using a data signal supplied to the liquid crystal display panel and a vertical / horizontal synchronizing signal; And And a backlight unit having an off interval for turning off the driving so as to be synchronized with a period in which the local motion blur of the liquid crystal display panel is detected by the image extracting unit in response to the backlight control signal output from the image extracting unit Wherein the liquid crystal display device is a liquid crystal display device. The method according to claim 1, Wherein the backlight unit is configured such that when the local motion blur area is varied according to the backlight control signal from the image extracting unit, the off period is changed so as to be synchronized with the motion blur period. The method according to claim 1, Wherein the image extracting unit comprises: A frame memory for storing data of a previous frame; And And a data comparator for comparing a data signal of a previous frame stored in the frame memory with a data signal of a current frame and detecting a local motion blur period using the vertical / horizontal synchronizing signal. The method according to claim 1, Wherein the image extracting unit controls the backlight unit to generate a backlight control signal so that driving of the backlight unit is turned off so as to be synchronized with the detected motion blur period. The method according to claim 1, Wherein the image extracting unit detects a motion blur period based on one frame.

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