KR101159333B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a driving method thereof to suitably adjust brightness enhancement and afterimage improvement effects by selectively applying black data insertion according to whether a moving picture or a still picture of an image is provided. Inserts black data in accordance with the range and position set in the image display panel, an image determining unit for judging the property of image data input from the outside, and selectively outputting image data, and an image data provided from the image determining unit. A black data processing unit which receives the black data processing unit and the image data into which the black data is inserted, compares the image data of two consecutive frames, and increases or decreases a predetermined voltage to a data voltage corresponding to the fluctuation range. Response speed improvement unit for outputting the and received directly from the image determination unit And a timing controller for controlling the panel according to image data or the new image data to implement an image.

Afterimage, Black Data, Image, Luminance, Moving Image, Still Image

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

1 is a view showing a pulse for driving a conventional cathode ray tube.

Fig. 2A is a diagram showing a driving waveform of a liquid crystal display device that mimics the impulse driving of the cathode ray tube.

FIG. 2B is a diagram showing an example of driving a screen by the driving waveform of FIG. 2A; FIG.

3 is a view showing an example of a liquid crystal display device according to the present invention;

4 is a view showing another example of a liquid crystal display device according to the present invention;

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

110: liquid crystal panel 120: timing control unit

130: black data processing unit 140: image determination unit

DATA: Image data

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a driving method thereof. In particular, in a liquid crystal display device which applies black data to an image for improving image quality, the liquid crystal display device may selectively select a moving picture or a still picture due to a characteristic of a moving picture or a still picture. The present invention relates to a liquid crystal display device and a driving method thereof for obtaining an optimum image quality improvement effect by applying black data.

Cathode ray tubes (CRTs) have been used in recent decades for displaying images. However, recently, the display device has been rapidly replaced by a liquid crystal display device that provides high luminance and clear image quality.

A liquid crystal display device is a device using optical anisotropy of liquid crystal, and injects a liquid crystal between two substrates, and applies various electric fields of various sizes to the liquid crystal to adjust light transmittance, thereby realizing various gray scale images.

The liquid crystal display device is thin and light in appearance and provides high clarity and brightness in terms of function, but can be driven with less than one third or less of the cathode ray tube of the same screen size in terms of power consumption. However, in implementing an image, there are some restrictions compared to cathode ray tubes.

For example, one of them is due to the viscosity and elasticity of the liquid crystal. The time required for the liquid crystal to react to the desired arrangement is longer than one frame, which is usually 16.7 ms. In this case, a tailing phenomenon may occur in which a picture of a previous frame remains faint.

The other reason is that the driving method of the liquid crystal display device is a holding method in which each pixel maintains a constant light transmittance by maintaining a constant data voltage for each frame. A motion blur in which a faint afterimage appears on the screen is shown. Symptoms may be caused.

Various image processing techniques have been developed to overcome the problems of the image realization of the liquid crystal display as described above, and a method of solving the disadvantages of the image realization of the liquid crystal display by adopting a cathode ray tube driving method has also been proposed.

1 is a view showing a pulse for driving a conventional cathode ray tube.

The cathode ray tube emits an electron beam and emits a phosphor, thereby displaying an image.

Referring to FIG. 1, the cathode ray tube generates an impulse every frame, and emits an electron beam according to the impulse to emit phosphors. That is, the image is realized by emitting the phosphor for only a short time in one frame section, and the emission of the phosphor occurs at a certain time interval so that no afterimage of the previous frame image remains.

By driving the liquid crystal display device by imitating the impulse driving of the cathode ray tube, the image quality deterioration due to the afterimage is improved.

FIG. 2A is a diagram showing a driving waveform of a liquid crystal display device imitating impulse driving of a cathode ray tube, and FIG. 2B is a diagram showing an example of driving a screen by the driving waveform of FIG. 2A.

Referring to FIG. 2A, black data BD is applied to a liquid crystal display during a part of one frame. The black data BD is image data representing the lowest gray scale. When the black data BD is applied, the screen is displayed in black. In this way, the image is supplied by supplying image data to the pixels in some sections of each frame, and the black screen is processed by supplying black data BD for the remaining sections, so that the liquid crystal display device is operated like an impulse driving a cathode ray tube. Drive it.

FIG. 2B shows an example of applying black data BD, and processes black data BD by 25% of the screen in every frame. When the black data BD is applied to the entire screen, the luminance of the image is too low to be applied at a predetermined ratio. In FIG. 2B, black data BD is applied to the entire screen over four frames by applying 25% of the screen.

As described above, by imitating the impulse driving of the cathode ray tube in the liquid crystal display, a part of the frame section is replaced with black data BD, thereby improving image quality. However, the black data BD is applied even in some sections of each frame, resulting in a decrease in overall luminance.

The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to selectively reduce black luminance by selectively applying black data according to characteristics of an image to be implemented in a liquid crystal display device applying black data. To provide a liquid crystal display device and a driving method thereof that suppresses the maximum.

The liquid crystal display device of the present invention for achieving the above object is set in a panel for displaying an image, an image determination unit for judging and selectively outputting the properties of the image data input from the vortex, and the image data provided from the image determination unit. The black data processing unit inserts and outputs the black data according to the range and position, and compares the image data of two consecutive frames by receiving the image data into which the black data is inserted, and compares the image data of two consecutive frames with a predetermined voltage to the data voltage corresponding to the fluctuation range. And a timing controller for controlling the panel according to the image data or the new image data provided directly from the image judging unit and outputting new image data by increasing or decreasing the value. .

The method for driving a liquid crystal display device according to the present invention includes analyzing image data to determine whether a moving image or a still image is included, and inserting black data into a part of the image data when the image data is a moving image; Comparing the image data of two consecutive frames by receiving the image data into which the black data is inserted, and increasing or decreasing a predetermined voltage to a data voltage corresponding to the fluctuation range to implement an image according to new image data; And if the image data is a still image, implementing the image according to the original image data in which black data is not inserted.

The present invention is characterized in that the black data is selectively applied according to the property of the image data in order to minimize the overall luminance decrease in the liquid crystal display device in which the black data is inserted in a certain section of each frame to improve the afterimage.

3 is a view showing an example of a liquid crystal display according to the present invention.

Referring to FIG. 3, a timing controller 120 for outputting image data DATA together with a plurality of control signals, a black data processor 130 for inserting and outputting black data as much as the range set in the image data DATA; The image determining unit 140 determines the property of the image data DATA input from the outside and selectively transmits the image data to the black data processing unit 130 or the timing control unit 120. It is configured to include a liquid crystal panel 110 to visually implement the image data (DATA).

The black data is image data DATA for displaying a black image on the liquid crystal panel 110 as image data DATA for representing an image of the lowest gray scale.

The image determining unit 140 analyzes the input image data DATA to determine whether the image is a moving image or a still image. The image data DATA input continuously in every frame unit can determine whether the moving image or the still image is compared by comparing two consecutive image data DATA.

The image determining unit 140 transmits the image data DATA to the black data processing unit 130 when determining that the image data DATA is a moving image and directly to the timing controller 120 when determining that the image data DATA is a moving image. . That is, the image realization process is processed differently according to a moving picture or a still picture.

In more detail, when the image determination unit 140 determines the image data DATA as a moving image and transmits the image data DATA to the black data processing unit 130, the black data processing unit 130 is an existing image. Black data is inserted into the data DATA. In this case, the black data is inserted into a part of the image data DATA of one frame according to a preset range and position and output to the timing controller 120.

For example, in order to apply black data corresponding to 25% of the entire screen, black data should be inserted as much as 20% of the image data (DATA) of every frame, and the position of inserting the black data every frame should be set to the position of the full screen. It should be shifted by a quarter.

Since moving images have a shorter period of changing the screen than still images, deterioration in image quality may be a problem. Therefore, as described above, even if the overall brightness is slightly lowered when the image data DATA is judged to be a moving image by the image determination unit 140, the black data is processed to the image data DATA through the black data processing unit 130. Insert some data to get the afterimage effect.

On the other hand, since still images have almost no change in screen compared to moving images, the deterioration in image quality due to afterimages is not significant. In this case, black data is not applied to the image data DATA in order to ensure the maximum brightness of the image. As shown in the figure, when the image determination unit 140 determines that the image data DATA is a still image, the image data DATA is directly transmitted to the timing controller 120. The timing controller 120 implements an image through the liquid crystal panel 110 according to the original image data DATA to which black data is not applied.

The timing controller 120 receives the image data DATA and generates a plurality of control signals for driving the liquid crystal panel 110 according to the image data DATA. Although not shown, control signals generated by the timing controller 120 are provided to a data driver and a gate driver for driving the liquid crystal panel 110 to drive the data driver and the gate driver.

The black data processor 130 may be included in the timing controller 120.

As described above, the liquid crystal display according to the present invention determines the property of the image data DATA through the image determination unit 140, and processes the image data DATA by black data only when the image is a moving image. Improve image quality In the case of a still image, since the luminance decrease may be greater than the afterimage removing effect obtained by inserting the black data, the original image data is implemented without inserting the black data, thereby reducing the luminance decrease of the image.

Meanwhile, when the image data DATA is a moving image, other image improvement algorithms may be applied together with the black data. For example, due to the slow response speed of the liquid crystal, a synergistic effect may also be obtained by applying the method of improving the response speed of the liquid crystal, which was developed to improve the tailing phenomenon, which is problematic in moving images.

4 is a view showing another example of a liquid crystal display according to the present invention.

First, a method of improving the response speed of a liquid crystal is a driving method of increasing the response speed of a liquid crystal to reach a desired arrangement state by setting an electric field applied to the liquid crystal to be larger than the original desired electric field. Thereby, the moving image realization quality can be improved.

4 is almost the same as the configuration of FIG. 3, so only different parts will be described.

Referring to FIG. 4, the image determiner 240 analyzes the image data DATA to determine whether the image is a moving image, and then, when the image data DATA is a moving image, the image determination unit 240 and the response speed improvement unit 135 are provided. Provide image data DATA.

The black data processor 130 inserts black data corresponding to the range and position set in the image data DATA. As such, the image data DATA having black data inserted therein is transmitted to the response speed improving unit 135.

The response speed improvement unit 135 compares the image data DATA of two consecutive frames, and further increases or decreases a predetermined voltage to the data voltage corresponding to the fluctuation range to output new image data. The timing controller 120 implements an image through the liquid crystal panel according to the new image data.

On the other hand, when the image data DATA is a still image, the image determination unit 140 transmits the image data DATA directly to the timing controller 120. The timing controller 120 implements an image through the liquid crystal panel 110 according to the raw image data DATA. Of course, when the image data DATA is a still image, it may be provided only to the response speed improvement unit 135.

As described above, the liquid crystal display device according to the present invention, in the liquid crystal display device to which the black data is applied, determines whether the image is a moving image or a still image, and selectively applies the black data only in the case of the moving image to greatly improve the afterimage. In the case of a still image, it is possible to prevent a decrease in luminance due to application of black data by implementing the image as the original image data without applying the black data.

Claims (10)

A panel displaying an image; An image judging unit for judging the property of image data continuously input from the outside in units of frames and selectively outputting image data; When the image data is a moving image, the black data which is the image data of the lowest gray scale shifted by 1/4 of the entire screen every frame among the one frame according to the range and position set in the image data provided from the image determining unit Black data processing unit for inserting and outputting; Receives the image data inserted with the black data, compares the image data of two consecutive frames, outputs new image data by increasing or decreasing a predetermined voltage to a data voltage corresponding to the fluctuation range, A response speed improvement unit for comparing new image data of two consecutive frames and outputting new image data by increasing or decreasing a predetermined voltage to a data voltage corresponding to the fluctuation range when the image data is a still image; And And a timing controller configured to control the panel according to the new image data to implement an image. delete delete The liquid crystal display of claim 1, wherein the black data processor is included in the timing controller. delete delete delete delete delete delete

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