KR101731820B1 - Liquid crystal display device and method of driving the same - Google Patents

Abstract

The present invention provides a liquid crystal display device comprising: a liquid crystal panel displaying an image; And a sharpness processing unit adapted to adaptively adjust the degree of the sharpness process in response to ambient brightness or image brightness, the sharpness process unit performing a sharpness process on a boundary portion where the gradation changes in the displayed image, Device.

Description

[0001] The present invention relates to a liquid crystal display device and a method of driving the same,

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 and a driving method thereof.

2. Description of the Related Art [0002] As an information-oriented society develops, demands for a display device for displaying an image have increased in various forms. Recently, a liquid crystal display (LCD), a plasma display panel (PDP) Various flat display devices such as an organic light emitting diode (OLED) have been utilized.

Of these flat panel display devices, liquid crystal display devices are widely used because they have advantages of miniaturization, weight reduction, thinness, and low power driving.

As a liquid crystal display device, an active matrix type liquid crystal display device in which switching transistors are formed in each of pixels arranged in a matrix form is widely used.

In such an active matrix type liquid crystal display device, when the gate wiring is scanned, a scan pulse is applied to turn on the switching transistor. In synchronism with this, the data voltage is transmitted through the data line and applied to the corresponding pixel. Accordingly, the data voltage is applied to the pixel electrode of the pixel, and the corresponding light is emitted.

Such a liquid crystal display device is a hold type display device, and the image is stopped and displayed during one frame. The display characteristic of such a liquid crystal display device serves as a cause of generating a motion blur, such as a moving object appearing to turn a tail when a moving image is displayed. That is, the motion blur occurs when the liquid crystal display device is a hold-type display device and the cognitive characteristics of the human eye are inconsistent with each other.

In other words, the eye of the user predicts the motion of the moving object, performs eye tracking continuously moving along the moving direction, and recognizes the image by integrating the optical information received through the eye tracking. On the other hand, since the liquid crystal display device is a hold-type display device, an object is stopped while displaying the same image during the current frame, and an object is displayed at a position separated by several pixels in a direction moving relative to the current frame during the next frame The process is repeated continuously. In this way, in the liquid crystal display device, objects are moved and displayed discretely in a frame cycle, and the display characteristics of the human eye and the display characteristics of the liquid crystal display device are different from each other The motion blur is generated due to inconsistency.

To improve such motion blur, various schemes have been suggested. One of these schemes has been proposed as a sharpness processing for emphasizing a part of an image that is an edge of an object. That is, in the sharpening process, the bright portion of the boundary portion in the image becomes brighter and the dark portion becomes darker. By thus artificially emphasizing the boundaries, the motion blur is significantly improved.

The degree of the conventional sharpness processing as described above has been processed to the same degree regardless of the brightness of the surrounding environment and the brightness of the image.

However, the brightness change perception characteristic of the user varies depending on the brightness of the surrounding environment or the brightness of the image. For example, when the brightness of the surrounding environment is bright, the threshold value for the brightness change is high and the threshold value for the brightness change is low when the brightness of the surrounding environment is low. Similarly, when the brightness of the image is bright, the threshold value for the brightness change is high, and when the brightness is dark, the threshold value for the brightness change is low.

In view of such brightness change perception characteristics, in the related art, the sharpness process is performed at the same level regardless of the brightness of the surrounding environment or the brightness of the image, so that the user feels that the effect on the sharpness process is reduced by half will be.

The present invention has a problem in providing a liquid crystal display device and a driving method thereof that can maximize the effect of sharpness processing.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display device comprising: a liquid crystal panel displaying an image; And a sharpness processing unit adapted to adaptively adjust the degree of the sharpness process in response to ambient brightness or image brightness, the sharpness process unit performing a sharpness process on a boundary portion where the gradation changes in the displayed image, Device.

Here, the apparatus may further include an ambient brightness detector for detecting the ambient brightness.

And an image analyzing unit for detecting the image brightness.

The sharpness processing unit may increase the degree of sharpness processing when the brightness of the surrounding environment is high and increase the degree of sharpness processing when the image brightness is high.

According to another aspect of the present invention, there is provided a method of adjusting a sharpness degree in a step of performing a sharpness process on a boundary portion where a gradation is changed in a displayed image, the method comprising adaptively adjusting a degree of the sharpness process in response to ambient brightness or image brightness Wow; And displaying the image subjected to the sharpening process on a liquid crystal panel.

Here, the step of adaptively adjusting the degree of the sharpness process in response to the brightness of the surrounding environment may include a step of increasing the degree of the sharpness process when the brightness of the surrounding environment is high, Adaptively adjusting the degree of processing may include increasing the degree of sharpness processing when the image brightness is high.

In the present invention, the degree of sharpness processing can be adaptively adjusted in response to ambient brightness or image brightness. Accordingly, even if the ambient brightness or the image brightness changes, the effect of the sharpening process can be maximized.

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

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

As shown in the figure, a liquid crystal display device 100 according to an embodiment of the present invention includes a liquid crystal panel 200, a driving circuit, and a backlight 600. The driving circuit includes a timing control unit 310, a gate driving unit 320, a data driving unit 330, a gamma reference voltage generating unit 340, and a sharpness processing unit 400. In addition, the driving circuit may include at least one of the ambient brightness detecting unit 510 and the image analyzing unit 520.

The liquid crystal panel 200 includes two substrates facing each other, for example, an array substrate and an opposite substrate, and a liquid crystal layer positioned between these two substrates.

A plurality of gate lines GL extending in the first direction and a plurality of data lines DL extending in the second direction intersect with each other on the array substrate of the liquid crystal panel 200 to form a matrix A plurality of arranged pixels P are defined.

Referring to FIG. 2, each pixel P is formed with a switching transistor T connected to a gate line and data lines GL and DL. The switching transistor T is connected to the pixel electrode. On the other hand, a common electrode is formed corresponding to the pixel electrode. When a voltage is applied to the pixel electrode and the common electrode, an electric field is formed between the pixel electrode and the common electrode, thereby driving the liquid crystal. The pixel electrode, the common electrode, and the liquid crystal located between these electrodes constitute a liquid crystal capacitor Clc. Each pixel P further includes a storage capacitor Cst, which serves to store the data voltage applied to the pixel electrode until the next frame.

When the liquid crystal panel 200 displays a color image, for example, red pixels, green pixels, and blue pixels may be formed, and adjacent red pixels, green pixels, The pixels constitute one image display unit.

The timing control unit 310 can receive a control signal from an external system such as a TV system or a video card. Then, the timing control unit 310 can receive the image data (Data) subjected to the sharpening process from the sharpness processing unit (400).

The timing controller 310 generates a gate control signal GCS for controlling the gate driver 320 and a data control signal DCS for controlling the data driver 330 using the input control signal. The timing controller 310 aligns the input image data Data and transmits the image data to the data driver 330.

The gamma reference voltage generator 340 divides the high voltage and the low voltage to generate a plurality of gamma reference voltages Vgamma and supplies the gamma reference voltages Vgamma to the data driver 330.

The gate driver 320 sequentially applies scan pulses to the plurality of gate lines GL in response to the gate control signal GCS.

For example, a plurality of gate lines GL are sequentially scanned every frame, and scan pulses are output to the gate lines GL during each scan period. Accordingly, in response to the turn-on voltage of the scan pulse, for example, the gate high voltage, the switching transistor T is turned on.

On the other hand, a turn-off voltage, for example, a gate low voltage is supplied to the gate line GL until the next frame scan. As such, during a period in which the gate-low voltage is supplied, the switching transistor T is turned off.

The gate driver 320 may be formed outside the liquid crystal panel 200 in the form of an IC device. On the other hand, the gate driver 320 can be formed directly on the array substrate of the liquid crystal panel 200 through a so-called GIP (gate in panel) method. For example, in the process of forming the array elements including the gate wirings and data wirings GL and DL of the array substrate, the switching transistors T, and the like in the display area, the gate driver 320 is connected to the non- As shown in FIG.

The data driver 330 supplies the data voltages to the plurality of data lines DL in response to the data control signal DCS supplied from the timing controller 310. [

For example, for the input gamma reference voltages Vgamma, it divides through the voltage dividing circuit to generate gradation voltages. Such gradation voltages correspond to the respective gradations that the image data Data can have.

Accordingly, the data driver 330 outputs the gradation voltage corresponding to the gradation of the input image data Data as the data voltage to the data line DL. Such a data voltage is output in synchronization with the scan of the gate line GL, and is input to the corresponding pixel P located in the scanned row line.

The backlight 600 serves to supply light to the liquid crystal panel 200. As the backlight 600, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED) may be used.

The sharpness processing unit 400 adjusts the gradation of the image data corresponding to the pixel positioned at the boundary portion so as to emphasize the boundary portion in which the brightness rapidly changes in the displayed image.

For example, such dark gradation is darkened with respect to image data that is located at one side of the boundary and expresses dark gradations. The bright gradation of the image data which is located on the other side of the boundary portion and expresses a bright gradation becomes brighter. As a result, the boundary portion becomes more conspicuously perceived, so that it is possible to improve the deterioration of image quality such as motion blur.

Meanwhile, in the embodiment of the present invention, the degree of sharpness processing in the sharpness processing unit 400, that is, the degree of gradation change in the boundary portion, can be adaptively adjusted according to the brightness of the surrounding environment or the brightness of the image. 3 to 6 will be described in more detail.

First, a method of adaptively adjusting the degree of sharpness processing according to the ambient brightness will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a diagram schematically illustrating a structure for adjusting the degree of sharpness processing according to the brightness of the surrounding environment as an example of the embodiment of the present invention. FIG. 4 shows an example of an embodiment of the present invention, And FIG.

3, the liquid crystal display 100 may include an ambient brightness detector 510. [ The ambient brightness detector 510 corresponds to a configuration for detecting the ambient brightness of the liquid crystal display device 100 when the liquid crystal panel 200 performs image display. As the ambient brightness detector 510, an optical measuring device such as an optical sensor or an illuminometer can be used.

In this manner, the ambient brightness detector 510 measures the brightness of the surrounding environment and transmits information related to the measured brightness of the surrounding environment to the sharpness processor 400.

The sharpness processing unit 400 determines the sharpness process degree by referring to the ambient brightness information transmitted from the surrounding brightness detection unit 510. [ In the embodiment of the present invention, the case where the brightness of the surrounding environment is relatively bright and the case where the brightness of the surrounding environment is relatively dark is described as an example.

The input image data Data_in for the image to be displayed during one frame is input to the sharpness processing unit 400. [ Here, the sharpness processing unit 400 analyzes input image data (Data_in) to specify at least one input image data (Data_in) located on both sides of the boundary where the brightness of the image to be displayed rapidly changes, The sharpness process is performed on the input image data Data_in. In this regard, referring to FIG. 4, input image data (Data_in) of a low gray level is positioned on the left side of the boundary portion, and input image data (Data_in) of high gray level is positioned on the right side of the boundary portion do.

In such a case, the sharpness process of lowering the grayscale of the input video data Data_in located on the left side and increasing the grayscale of the input video data Data_in located on the right side is performed. As a result, the degree of the gradation change at the boundary portion increases. Thus, the input image data (Data_in) subjected to the sharpening process is output as the output image data (Data_out).

Here, when the brightness of the surrounding environment is bright, the degree of the gradation change at the boundary portion is relatively increased, and when the brightness of the surrounding environment is dark, the degree of the gradation change at the boundary portion is relatively decreased.

In this regard, in terms of cognitive characteristics with respect to brightness change, when the ambient brightness is bright, the threshold value for recognizing the brightness change is relatively high. Therefore, if the brightness of the surrounding environment is bright and the degree of gradation change at the boundary portion becomes relatively low, the user will not be able to easily recognize the boundary portion. Considering this point, it is more advantageous in terms of recognizing the boundary portion to increase the degree of the gradation change at the boundary portion relatively when the brightness of the surrounding environment is bright.

When the ambient brightness is low, the threshold value for recognizing the brightness change is relatively low. Therefore, if the brightness of the surrounding environment is dark and the degree of the gradation change at the boundary portion becomes relatively high, the user will not be able to easily recognize the phenomenon such as the glare with respect to the boundary portion. Considering this point, in the case where the brightness of the surrounding environment is dark, it is more advantageous in terms of recognizing the boundary portion to relatively increase the degree of the gradation change at the boundary portion.

Therefore, in the embodiment of the present invention, when the brightness of the surrounding environment is bright, the operation of relatively increasing the degree of sharpness processing is performed in order to relatively increase the brightness change at the boundary portion. On the other hand, when the brightness of the surrounding environment is low, the degree of sharpness processing is relatively lowered in order to relatively reduce the brightness change at the boundary portion.

Thus, the user can easily recognize the boundary portion in the image regardless of the brightness of the surrounding environment.

As described above, the liquid crystal display device 100 according to the embodiment of the present invention can adaptively adjust the degree of sharpness processing in response to the brightness of the surrounding environment. Thus, even if the ambient brightness changes, the effect of the sharpening process can be maximized.

On the other hand, in the above description, the method of adjusting the gradation of the image data located on both sides of the boundary portion has been mainly described in connection with the sharpening process on the brightness of the surrounding environment. On the other hand, in some cases, the grayscale of the video data located on one side of the boundary portion may be adjusted during the sharpening process. As described above, the sharpness process in the embodiment of the present invention can be performed by adjusting the gradation of the image data located at least one side of the boundary portion.

Next, a method of adaptively adjusting the degree of sharpness processing according to the image brightness will be described with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a diagram schematically illustrating a configuration for adjusting the degree of sharpness processing according to image brightness as another example of the embodiment of the present invention. FIG. 6 shows another example of the embodiment of the present invention, And FIG.

5, the liquid crystal display device 100 may include an image analysis unit 520. [ When the liquid crystal panel 100 performs image display, the image analyzer 520 can perform image analysis on a frame-by-frame basis, thereby detecting the brightness of a displayed image.

In this way, the image analyzer 520 analyzes the image brightness and transmits information related to the analyzed image brightness to the sharpness processor 400.

The sharpness processing unit 400 refers to the image brightness information transmitted from the image analysis unit 520 to determine the degree of sharpness processing. In the embodiment of the present invention, the case where the image brightness is relatively bright and the case where the image brightness is relatively low will be described as an example.

The input image data Data_in for the image to be displayed during one frame is input to the sharpness processing unit 400. [ Here, the sharpness processing unit 400 analyzes input image data (Data_in) to specify at least one input image data (Data_in) located on both sides of the boundary where the brightness of the image to be displayed rapidly changes, The sharpness process is performed on the input image data Data_in.

In this regard, referring to FIG. 6, input image data (Data_in) of low gradation is located on the left side of the boundary portion, and input image data (Data_in) of high gradation is located on the right side of the boundary portion.

In such a case, the sharpness process of lowering the grayscale of the input video data Data_in located on the left side and increasing the grayscale of the input video data Data_out located on the right side is performed. As a result, the degree of the gradation change at the boundary portion increases. Thus, the input image data (Data_in) subjected to the sharpening process is output as the output image data (Data_out).

Here, when the image brightness is bright, the degree of the gradation change in the boundary portion is relatively increased, and when the image brightness is dark, the degree of the gradation change in the boundary portion is relatively decreased.

In this regard, in a similar manner to that described above with respect to the brightness of the surrounding environment, the threshold value for recognizing the brightness change is relatively high when the image brightness is bright, in terms of the cognitive characteristics with respect to the brightness change. Therefore, if the image brightness is bright and the degree of gradation change at the boundary portion is relatively low, the user will not be able to recognize the boundary portion easily. Taking this into consideration, when the image brightness is bright, it is more advantageous in terms of recognition of the boundary portion to relatively increase the degree of the gradation change at the boundary portion.

When the image brightness is dark, the threshold value for recognizing the brightness change is relatively low. Therefore, if the brightness of the image is dark and the degree of the gradation change at the boundary portion becomes relatively high, the user will feel a phenomenon such as a glare with respect to the boundary portion, and thus it will not be easily recognized. Considering this point, in the case where the image brightness is dark, it is more advantageous in terms of recognition of the boundary portion to relatively increase the degree of the gradation change at the boundary portion.

Therefore, in the embodiment of the present invention, when the image brightness is bright, an operation of relatively increasing the degree of sharpness processing is performed in order to relatively increase the brightness change at the boundary portion. On the other hand, when the image brightness is dark, an operation of relatively lowering the degree of sharpness processing is performed in order to relatively reduce the brightness change at the boundary portion.

Thus, the user can easily recognize the boundary portion in the image regardless of the brightness of the surrounding environment.

As described above, the liquid crystal display device 100 according to the embodiment of the present invention can adjust the degree of sharpness processing adaptively in response to the image brightness. Thus, even if the image brightness changes, the effect on the sharpness process can be maximized.

On the other hand, in the above description, the method of adjusting the gradation of the image data located on both sides of the boundary portion has been mainly described with respect to the sharpness processing on the image brightness. On the other hand, in some cases, when sharpening is performed, the grayscale of the video data located on one side of the boundary portion can be adjusted. As described above, the sharpness process in the embodiment of the present invention can be performed by adjusting the gradation of the image data located at least one side of the boundary portion.

Meanwhile, with respect to the sharpness process for the image brightness, the image analyzed by the image analyzer 520 may be the image of the previous frame, and the image subjected to the sharpening process may be the image of the current frame. Of course, the image analyzed by the image analyzing unit 520 and the image subjected to sharpness processing may be images of the same frame.

As described above, in the embodiment of the present invention, the sharpness process degree can be adaptively adjusted in response to the ambient brightness or the image brightness. Accordingly, even if the ambient brightness or the image brightness changes, the effect of the sharpening process can be maximized.

The embodiment of the present invention described above is an example of the present invention, and variations are possible within the spirit of the present invention. Accordingly, the invention includes modifications of the invention within the scope of the appended claims and equivalents thereof.

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

Figure 2 schematically illustrates the structure of a pixel according to an embodiment of the present invention;

3 is a diagram schematically showing a configuration for adjusting the degree of sharpness processing according to the brightness of the surrounding environment as an example of the embodiment of the present invention.

4 is a view schematically showing a state in which the degree of sharpness processing is adjusted according to the brightness of the surrounding environment as an example of the embodiment of the present invention.

5 is a view schematically showing a configuration for adjusting the degree of sharpness processing according to image brightness as another example of the embodiment of the present invention.

6 is a view schematically showing a state in which the sharpness process degree is adjusted according to the image brightness as another example of the embodiment of the present invention.

Description of the Related Art

100: liquid crystal display device 200: liquid crystal panel

310: timing control unit 320: gate driving unit

330: Data driver 340: Gamma reference voltage generator

400: Sharpness processing unit 510: Ambient brightness detecting unit

520: image analysis unit 600: backlight

GL: gate wiring

DL: Data wiring

P: pixel

Claims (8)

A liquid crystal panel for displaying an image; And a sharpness processing unit for adaptively adjusting the degree of the sharpness process in response to ambient brightness or image brightness, the sharpness process unit performing a sharpness process on a boundary portion where the gradation changes in the displayed image, In the sharpness process of the sharpness processing section, the gradation of the low gradation image data on one side of the boundary portion is lowered, the gradation of the high gradation image data on the other side of the boundary portion is increased, Wherein the sharpness processing unit increases the degree of sharpness processing when the brightness of the surrounding environment is high and increases the degree of sharpness processing when the image brightness is high Liquid crystal display device. The method according to claim 1, And a surrounding brightness detecting unit for detecting the brightness of the surrounding environment. The method according to claim 1, And an image analyzer for detecting the image brightness. delete The method comprising: adjusting a degree of the sharpness process in response to ambient brightness or image brightness, the method comprising: adaptively adjusting a degree of the sharpness process in response to ambient brightness or image brightness; And displaying the image subjected to the sharpening process on a liquid crystal panel, In the sharpening process, the gradation of the low gradation image data on one side of the boundary portion is lowered, the gradation of the high gradation image data on the other side of the boundary portion is increased, Wherein the step of adaptively adjusting the degree of the sharpening process in response to the brightness of the surrounding environment includes a step of increasing the degree of the sharpening process when the brightness of the surrounding environment is high, Wherein adaptively adjusting the degree of the normal sharpness process in response to the image brightness includes increasing the degree of sharpness process when the image brightness is high A method of driving a liquid crystal display device. delete delete delete

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