KR102231156B1 - Display device and data compensation method thereof - Google Patents

Abstract

The present invention relates to a display device, wherein a logo data compensating unit for generating new logo data by modulating the data of the logo image using background data around a logo image, and input image data including the new logo data to pixels And a display panel driver to write to.

Description

Display device and its data compensation method {DISPLAY DEVICE AND DATA COMPENSATION METHOD THEREOF}

The present invention relates to a display device and a data compensation method thereof.

Organic Light Emitting Diode Display (hereinafter referred to as "OLED display"), Liquid Crystal Display Device (LCD), Plasma Display Panel (PDP), field emission display device ( Various flat panel displays such as Field Emission Display, FED) are being used.

A liquid crystal display device displays an image by controlling an electric field applied to liquid crystal molecules according to a data voltage. Active matrix type liquid crystal display devices have been applied to almost all display devices, from small mobile devices to large TVs, and are widely used due to lower cost and higher performance thanks to the development of process technology and driving technology.

Since the OLED display device is a self-luminous device, power consumption is lower than that of a liquid crystal display device that requires a backlight and can be manufactured to be thinner. In addition, the OLED display has a wide viewing angle and a fast response speed. OLED display devices are expanding the market while competing with liquid crystal display devices.

In general, a logo displayed on a display device is displayed in the same pixel in primary color. The same grayscale data is applied to pixels on which the logo is displayed for a long period of time to receive DC stress. Due to this, even if the logo disappears, an afterimage of the logo may be seen. Logos are mostly primary color images. For this reason, in the pixel at the logo position, a sub-pixel of a specific color displays data of the highest gradation, and a sub-pixel of another color displays data of gradation zero. The higher the data voltage is, the faster the deterioration of the pixels proceeds. Accordingly, the degree of deterioration of the pixels on which the logo is displayed varies for each sub-pixel, and an afterimage of a specific color may be seen.

In the case of an OLED display, a driving element of a pixel is implemented as a TFT, and when a DC voltage is applied to the gate of the driving element, the threshold voltage is shifted due to DC gate bias stress. Accordingly, pixels displaying a logo deteriorate faster than pixels displaying a moving image.

There is a method of lowering the gradation value of the logo data in order to improve the problem of afterimages caused by the logo and the decrease in lifespan, but there is a limit to lowering the brightness of the logo. This method can improve the luminance afterimage caused by the logo image, but has no effect on improving the color afterimage. Even if the gradation of the logo data is lowered, since there is a sub-pixel displaying gradation 0 in the pixel where the logo is displayed, a problem in which the degree of deterioration is different for each sub-pixel cannot be improved, so that the afterimage of a specific color is not improved.

The present invention provides a display device capable of reducing an afterimage caused by a logo image and a data compensation method thereof.

The display device of the present invention includes a logo detection unit for detecting a logo image from an input image, a logo data compensating unit for generating new logo data by modulating data of the logo image using background data around the logo image, and the new logo And a display panel driver that writes input image data including data to pixels.

The logo data compensator extracts the data of the logo image from the input image, and generates data to be written in pixels at the location where the data of the logo image is extracted, as data generated by smoothing the background data around the logo image. do. The logo data compensator generates the new logo data by multiplying the data of the logo image by a first weight, multiplying the data generated by the smoothing technique by a second weight, and dividing the sum by the sum of the first and second weights. .

Due to the new logo data, the logo image appears as a translucent image.

The data compensation method of the display device includes detecting a logo image from an input image, generating new logo data by modulating data of the logo image using background data around the logo image, and generating new logo data. And writing the included input image data to pixels of the display panel.

The present invention modulates the logo data into moving image background data around the logo, thereby reducing the difference in deterioration between neighboring pixels and between neighboring subpixels by changing DC stress caused by the logo into AC stress. As a result, the present invention can reduce a luminance afterimage and a color afterimage due to a logo image and improve the life of the display device.

1 is a block diagram showing a display device according to an exemplary embodiment of the present invention.
2 is a flowchart showing a data compensation method according to an embodiment of the present invention.
3 is a diagram illustrating an example of an image including a logo.
4A is a diagram illustrating an image in which only a logo is extracted from the image of FIG. 3.
FIG. 4B is a diagram illustrating a background image from which a logo is extracted from the image of FIG. 3.
4C is a diagram illustrating an example in which a logo image is translucent in the image of FIG. 3.
5 is a diagram showing deterioration of pixels due to a logo image.

The display device of the present invention may be implemented as a flat panel display device such as an OLED display device, a liquid crystal display device (LCD), a plasma display panel (PDP), and a field emission display device (FED). The following embodiments will be described based on an OLED display, but the present invention is not limited thereto.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numbers throughout the specification mean substantially the same elements. In the following description, when it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 shows a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the display device of the present invention includes a display panel 100, a logo detection unit 106, a logo data compensation unit 108, and a display panel driver.

A plurality of data lines 11 and a plurality of scan lines (or gate lines) 12 cross the pixel array of the display panel 100. The pixel array of the display panel 100 includes pixels that are arranged in a matrix form to display an input image. Each of the pixels includes a red (R) subpixel, a green (G) subpixel, and a blue (B) subpixel. Each of the pixels may further include a white (W) sub-pixel.

Each of the sub-pixels includes an OLED, one or more TFTs (Thin Film Transistor), a driving TFT, a capacitor, etc. OLED is a hole injection layer (HIL), a hole transport layer (HTL). ), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL), etc. Organic compound layers are stacked in an OLED structure in which electrons and holes are combined in the emission layer. In addition, each of the sub-pixels may further include an internal compensation circuit, which includes one or more switch TFTs and one or more capacitors to compensate for changes in characteristics of the driving TFT.

The logo detection unit 106 analyzes data of an input image input from the host system 200 and detects data of a logo image (hereinafter, referred to as "logo data"). The logo data detection method can be any known method. For example, in the present invention, a logo image may be detected by the logo detection method disclosed in patent application 10-2013-0139810 (2013. 11. 18).

After the logo data compensating unit 108 extracts the logo data from the input image, the logo data is modulated by using background image data (hereinafter referred to as "background data") around the logo to pixels at the logo position. The background data may be data of a moving image.

The logo data modulation method is a known smoothing technique to generate new logo data that changes according to the background image. The new logo data is written to the pixels in place of the original logo data. The smoothing technique is a method of modulating data with surrounding data using a mean filter, a median filter, or the like.

The logo data compensating unit 108 multiplies the data of the logo image by a first weight (A) as shown in Equation 3, and multiplies the data generated by the smoothing technique by a second weight (B) and adds the result of the sum of the first and second weights. Divide by the sum of weights (A+B) to generate new logo data. The new logo data generated by the logo data compensating unit 108 reflects the background data, so the luminance and chromaticity change according to the background image. The logo image displayed on the display panel becomes translucent due to the new logo data, so that the background image is visible.

Since the new logo data changes according to the background image, the pixels to which the logo data is written are subjected to AC stress. As shown in FIG. 5, the AC stress can alleviate the deterioration of the pixels compared to the DC stress. Since the luminance and chromaticity of new logo data varies depending on the background data, all sub-pixels in the pixel are driven when the logo image is displayed, and deterioration proceeds to a similar level. Accordingly, the present invention can improve the deterioration of pixels on which a logo image is displayed to extend the life of the display device, as well as solve the luminance afterimage and color afterimage caused by the logo image.

The display panel driver includes a data driver 102, a gate driver 104, a timing controller 110, and the like. The display panel driver writes data of an input image to pixels of the display panel 100.

The data driver 102 converts the pixel data received from the timing controller 110 into an analog gamma compensation voltage, generates a data voltage, and outputs the data voltage to the data lines 11. Pixel data input to the data driver 102 is digital video data of an input image. The pixel data may include new logo data generated by the logo data compensating unit 108.

The gate driver 104 supplies scan pulses (or gate pulses) synchronized with the output voltage of the data driver 102 to the scan lines 12 under the control of the timing controller 110. The gate driver 104 sequentially selects pixels to which data is written by sequentially shifting the scan pulses in units of lines.

The timing controller 110 receives input image data modulated with the logo data by the logo data compensation unit 108. In addition, the timing controller receives timing signals synchronized with the input image data. The timing signals include a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a data enable signal (DE), a dot clock (CLK), and the like. The timing controller 110 transmits the input image data to the data driver 102.

The timing controller 110 controls operation timings of the data driver 102 and the gate driver 104 based on timing signals synchronized with the input image data. The timing controller 110 generates a data timing control signal and a gate timing control signal based on the timing signals to synchronize the data driver 102 and the gate driver 104. The data timing control signal defines the operation timing and output timing of the data driver 102. The gate timing control signal defines the operation timing and output timing of the gate driver 104.

The host system 200 may be implemented as any one of a TV (Television) system, a set-top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system.

The logo detection unit 106 and the logo data compensation unit 108 may be embedded in the host system 200 or the timing controller 110.

2 is a flowchart showing a data compensation method according to an embodiment of the present invention. 3 is a diagram illustrating an example of an image including a logo. 4A is a diagram illustrating an image in which only a logo is extracted from the image of FIG. 3. FIG. 4B is a diagram illustrating a background image from which a logo is extracted from the image of FIG. 3. 4C is a diagram illustrating an example in which a logo image is translucent in the image of FIG. 3.

2 to 4, the data compensation method of the present invention detects a logo image from an input image and extracts logo data (S1 to S3).

In the image of FIG. 3, the logo image 31 is an opaque primary color image separated from the background image 32. If only the logo image 31 is extracted from the image of FIG. 3, it is the same as that of FIG. 4A. When the logo data is extracted, all of the logo data becomes zero, so the logo image looks black as shown in FIG. 4B. As shown in FIG. 4B, the data LMB _ij from which the logo data is extracted may be expressed as Equation 1.

Here, Data _ij is input image data (Data _ij ), and LM _ij is logo data. ij is the coordinate of the pixel and indicates the location where the i row and the j column intersect.

Subsequently, the data compensation method of the present invention _{applies a smoothing technique to the logo image of the data LMB ij} from which the logo data is extracted. The smoothing technique may apply a 3×3 mean filter. The 3×3 mean filter generates data to be written in a center pixel in a 3×3 pixel matrix as an average value of the data of eight pixels around it. _{Equation 2 represents data LI ij} modulated by applying a 3×3 mean filter to the logo image of the _{data LMB ij} from which the logo data is extracted. The mean filter mask size is not limited to 3×3.

The data compensation method of the present invention generates new logo data by using a first weight (A) for emphasizing the original logo data and a second weight (B) for emphasizing the background data around the logo. The first weight A and the first weight B are preset and stored in the memory. The first weight A and the first weight B may vary according to a model of the display panel or driving characteristics. _{New logo data (Data'ij} ) generated by the data compensation method is shown in Equation 3. The new logo data Data' _ij is input to pixels at the logo location including background data around the logo (S4 and S5).

As can be seen from Equation 3, when A is large, the color of the original logo data is emphasized in the logo image, and when B is large, the color of the background image is emphasized. By appropriately adjusting the first and second weights A and B, the color or transparency level of the logo image can be adjusted, and the amount of AC stress of the pixels can be adjusted.

4C is an image in which logo data is _{changed to logo data (Data'ij} ) as shown in Equation 3. As shown in FIG. 4C, since the data compensation method of the present invention modulates the logo data with background data around the logo, the logo image is translucent, and the background image is visible from the logo image.

5 is a diagram showing deterioration of pixels due to a logo image. The logo data before data modulation is subjected to direct current stress to each of the sub-pixels, and a sub-pixel having a gradation of 0 is present, thereby increasing the difference in the level of degradation of the sub-pixels. In the example of Fig. 5, the color of the logo is red. In red, the gradation (G) of the red sub-pixel is 255, and the gradation of the sub-pixels of other colors is 0. According to the present invention, new logo data including background data around a logo is input to pixels at a logo position, so that data changes in each of the sub-pixels whenever the background data changes.

According to the present invention, by changing the stress of pixels to which the logo data is written into AC stress, the speed of deterioration of the pixels may be slowed, thereby mitigating the deterioration of the pixels. Since the luminance and chromaticity of new logo data varies depending on the background data, all sub-pixels in the pixel are driven when the logo image is displayed, and deterioration proceeds to a similar level. Accordingly, the present invention can improve the deterioration of pixels on which a logo image is displayed to extend the life of the display device, as well as solve the luminance afterimage and color afterimage caused by the logo image.

It will be appreciated by those skilled in the art through the above description that various changes and modifications can be made without departing from the technical idea of the present invention. Accordingly, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be determined by the claims.

100: display panel 102: data driver
104: gate driver 106: logo detection unit
108: logo data compensation unit 110: timing controller
200: host system

Claims (7)

A logo detector for detecting a logo image from the input image;
A logo data compensator for generating new logo data by modulating data of the logo image using background data around the logo image; And
A display panel driver for writing input image data including the new logo data to pixels,
The logo data compensation unit,
Extracting the data of the logo image from the input image,
Data to be written to pixels at the location where the data of the logo image is extracted is generated as logo data modulated by applying a smoothing technique to background data around the logo image,
A value obtained by multiplying the data of the logo image by a first weight and a value obtained by multiplying the modulated logo data by a second weight are summed, and the new logo data is divided by the sum of the first weight and the second weight. Generating display. delete The method of claim 1,
A display device in which the logo image is viewed as a translucent image due to the new logo data. Detecting a logo image from the input image;
Generating new logo data by modulating data of the logo image using background data around the logo image; And
And writing input image data including the new logo data to pixels of a display panel,
Generating the new logo data,
Extracting data of a logo image from the input image;
Generating data to be written in pixels at a location from which the logo image data is extracted as modulated logo data by applying a smoothing technique to background data around the logo image; And
A value obtained by multiplying the data of the logo image by a first weight and a value obtained by multiplying the modulated logo data by a second weight are summed, and the new logo data is divided by the sum of the first weight and the second weight. Data compensation method of a display device comprising the step of generating. delete The method of claim 1,
The first weight is a value that emphasizes data of the logo image, and the second weight is a value that emphasizes the surrounding background data. The method of claim 4,
The first weight is a value for emphasizing the data of the logo image, and the second weight is a value for emphasizing the surrounding background data.

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