KR102435903B1 - Display device and method for driving the same - Google Patents

Abstract

The present invention relates to a display device and a driving method thereof, comprising: a data processing unit that modulates data by increasing a gain of data to be written in a first pixel higher than a gain of data to be written in a second pixel; and a driving unit for writing to pixels. The present invention can realize a brighter screen without color distortion in a display device having a wide color gamut.

Description

DISPLAY DEVICE AND METHOD FOR DRIVING THE SAME

The present invention relates to a color according to a change in color gamut of a wide gamut display panel (hereinafter referred to as “RGBW display panel”) composed of three sub-pixels each displaying primary color data and one sub-pixel displaying white data. A display device that optimizes a trade-off between luminance and color distortion of an RGBW display panel by quantifying color distortion, and a method of driving the same.

In general, an image display device such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, etc. is a red (R), green (G), blue (Blue) display device. An input image can be displayed on an RGBW display panel in which each pixel composed of the three sub-pixels of ; B) is arranged in a matrix form. Hereinafter, such a display device will be referred to as a “RGBW pixel structure display device”. 1 schematically shows the structure of one pixel in an OLED display having an RGBW pixel structure.

Referring to FIG. 1 , in an OLED display having an RGBW pixel structure, a W OLED device (WOLED) emitting white light and an RGB color filter (CF) and a W region (transparent region) respectively formed thereon are arranged in a horizontal direction or , can be arranged in the form of a 2×2 matrix.

WOLED devices output W light (white light) containing all visible light spectral components. The RGB color filter of the RGB sub-pixel filters only the spectral component of the corresponding wavelength from among the W lights to respectively output the RGB light, and the transparent region of the W sub-pixel outputs the W light as it is. Therefore, when the WOLED device outputs 100% luminance, the luminous efficiency of the W sub-pixel is better than that of the RGB sub-pixel.

When the luminance of the WOLED device is reduced at the same rate through data modulation to reduce power consumption, the RGB sub-pixel has a large power consumption reduction effect compared to the luminance decrease, whereas the W sub-pixel has a large power consumption reduction effect compared to the luminance decrease. , W sub-pixels are inefficient in reducing power consumption. In order to reduce power consumption in an OLED display having an RGBW pixel structure, when data of RGBW sub-pixels is reduced by the same ratio, a decrease in luminance perceived by a user (hereinafter, “perceived luminance”) occurs. In order to prevent a decrease in perceived luminance, only the RGB data value can be reduced while maintaining the W data value, but this method allows the user to perceive color distortion.

The problem of perceived luminance degradation and perceived color distortion may occur in all image display devices using an RGBW sub-pixel structure, such as an RGBW pixel structure LCD as well as an RGBW pixel structure OLED display device.

In Korean Patent Laid-Open Patent Publication 10-2014-0081394 (July 01, 2014), the applicant of the present application discloses a method for further reducing RGB data than W data by applying different gains to RGB data and W data in consideration of the luminous efficiency of each RGBW sub-pixel. As a method, a method for reducing power consumption without lowering perceived luminance has been proposed. In this method, color distortion due to data modulation is calculated using letinex theory, and a gain is adjusted in order to reduce the quantified color distortion component through this method.

In LCD or OLED display devices, it is being commercialized with a wide WCG of 100 to 150% compared to the NCG color gamut (sRGB). Wide color gamut (hereinafter referred to as “WCG”) technology is becoming more common in display devices such as LCD or OLED display devices. WCG has a characteristic that the color luminance perception characteristics of chromatic colors appear brighter than the normal color gamut (hereinafter referred to as “NCG”) according to hue and saturation. This property is known as the H-K effect (Helmholtz-Kohlrausch effect). Color distortion in RGBW display panels is caused by color contrast between bright achromatic colors and dark chromatic colors. Therefore, if the perceived luminance of chromatic colors is increased due to the H-K effect in WCG, color distortion that can be perceived by the user may increase due to color contrast.

The present invention has been devised to solve the problems of the prior art, and provides a display device and a method of driving the same that can realize a brighter screen without color distortion in consideration of the color distortion characteristics of an RGBW display panel with respect to a change in color gamut. to provide.

In the display device of the present invention, the gain of data to be written in the first pixel is applied to the second pixel so that the achromatic luminance of the first pixel displaying the first color is higher than the achromatic luminance of the second pixel displaying the second color. and a data processing unit that modulates the data by increasing the gain of the data to be written, and a driving unit that writes the data modulated by the data processing unit into the pixels.

The first color has a lower contribution of color distortion than the second color in a wide color gamut.

The data processing unit includes: a data conversion unit for converting RGB data into RGBW data of a wide color gamut; a color distortion calculator configured to calculate a color distortion proportional to a color distortion contribution of an input color using a preset color distortion contribution curve and a preset color distortion calculation equation; a gain calculator for adjusting the gain to a value inversely proportional to the color distortion; and a data modulator for modulating the data by multiplying the data by the gain for each pixel.

When the display device displays a first image including the block of the first color and a white background and a second image including the block of the second color and the white background on the display panel, the white background of the first image is displayed on the display panel. The luminance is higher than the luminance of the white background of the second image.

In the method of driving the display device, in the first and second colors having the same grayscale, the achromatic luminance of the first pixel displaying the first color is higher than the achromatic luminance of the second pixel displaying the second color. and modulating the data by increasing a gain of data to be written into one pixel higher than a gain of data to be written into the second pixel, and writing data modulated by the data processing unit into the pixels.

The display device and the driving method according to the present invention quantify the degree of color distortion due to color gamut change and adjust the gain according to the color distortion, thereby realizing a brighter screen without color distortion in the RGBW display panel of the WCG color gamut. have.

1 is a diagram schematically showing the structure of one pixel in an OLED display having an RGBW pixel structure.
2 is a diagram illustrating a change in a pixel gain according to data saturation.
3 is a diagram comparing the HK effect factor of NCG and the HK effect factor of WCG with respect to an input color chart in which various hues and saturation are expressed.
4 is a diagram showing a ratio of an HK effect factor between WCG and NCG.
5 is a diagram illustrating a method of generating a color distortion contribution curve of WCG versus NCG.
6 is an image of experimental results comparing color distortion and perceived luminance between the present invention and Comparative Example 1 according to color gamut change.
7 is a diagram illustrating in detail a processing procedure of the method for compensating for color gamut and color distortion according to the present invention.
8 is a diagram illustrating a phenomenon in which achromatic luminance changes when sample images having different color distortion contributions in the WCG gamut are displayed on a display device having an RGBW pixel structure in the WCG gamut.
9 is a block diagram illustrating a display device according to an embodiment of the present invention.
FIG. 10 is a block diagram illustrating the data processing unit shown in FIG. 9 in detail.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

As a result of examining the actual power consumption ratio in the OLED display device having the RGBW pixel structure, the inventors of the present application confirmed that the efficiency of the W sub-pixel is more than twice that of the other RGB sub-pixels. Therefore, in order to reduce the power consumption while minimizing the decrease in luminance, it is more efficient to reduce the RGB data than the W data.

In Korean Patent Laid-Open Patent Publication No. 10-2014-0081394 (July 01, 2014), in order to reduce power consumption in consideration of the luminous efficiency of each RGBW sub-pixel, different gains are obtained for data of primary color (RGB) and data of W A method to reduce power consumption while maintaining luminance degradation below the perceived level by modulating RGBW data by applying Color distortion components caused by the application of different gains are calculated using Retinex theory, which is one of the cognitive theories, and recognized by controlling the gain so that the calculated color distortion components converge to the target value. Power consumption can be reduced while maintaining the color distortion below the perceived level.

According to the Retinex theory, the color perceived by humans is determined not only by the color but also by the normalization that is affected by the surrounding color. Therefore, the Retinex Theory explains how the color is distorted due to the surrounding colors, such as simultaneous contrast, in which the chromatic colors of other RGB subpixels appear to be very dark when the W subpixel is brightened in an image display device having an RGBW structure.

Based on this, the color distortion of one wavelength of RGB in each pixel is calculated as in Equation 1.

는 i 번째 픽셀에서 인지 컬러이다.

는 RGB 데이터에 제1 게인이 곱해지고 W 데이터에 제2 게인이 곱해져 RGBW 데이터가 변조될 때 픽셀의 인지 컬러이다. Ki는 이전 프레임에서 i 번째 픽셀의 게인이다.

는 현재 프레임에서 전체 픽셀들에 적용되는 게인의 평균 즉,

(N은 전체 픽셀 수)이다. 게인은 프레임 게인과 픽셀 게인의 합이다.Here, DRΛ(i) is the color distortion of any i-th pixel, and Λ(waveband) is the wavelength of one of RGB.

is the perceived color at the i-th pixel.

is the perceived color of a pixel when RGBW data is modulated by multiplying RGB data by a first gain and by multiplying W data by a second gain. Ki is the gain of the i-th pixel in the previous frame.

is the average of the gains applied to all pixels in the current frame, that is,

(N is the total number of pixels). The gain is the sum of the frame gain and the pixel gain.

The frame gain is a gain applied equally to all pixels. The frame gain is equal to k in FIG. 2 . The frame gain may be determined by a method proposed in Korean Patent Application Laid-Open Publication No. 10-2007-0065640 (June 25, 2007). As suggested in Korean Patent Application No. 10-2008-0061772 (July 03, 2008), the pixel gain may be calculated as a value inversely proportional to the saturation of RGB data. In Fig. 2, Min is the minimum value of RGB data, and Max is the maximum value of RGB data. The closer Min/Max is to 1, the less saturated the achromatic color is, and the closer to 0, the more saturated the chromatic color is. Accordingly, the pixel gain is higher as it approaches an achromatic color. The pixel gain may be determined according to the slope of a straight line connecting the frame gain k and the upper limit gain value AGP in FIG. 2 . The sum of the frame gain and the pixel gain is determined to be less than or equal to the upper limit gain value (AGP). In FIG. 2 , the sum of the frame gain and the pixel gain is an example determined in a range between 1 and 2, but is not limited thereto. The upper limit gain value (AGP) varies according to the average color distortion (ACD).

The average color distortion (ACD) within one frame is expressed by Equation 2 below.

Here, DR ^R (i) is the color distortion at the R wavelength, and DR ^G (i) is the color distortion at the G wavelength. DR ^B (i) is the color distortion at B wavelength.

The color distortion is determined according to the slope of a straight line connecting the frame gain k and the upper limit gain value AGP in FIG. 2 . Color distortion can be optimized by adjusting the upper limit gain (AGP).

는 다음 프레임에 적용될 상한 게인 값(AGP)이고,

는 현재 프레임의 상한 게인 값(AGP)이다.

는 인지 색 왜곡 수준 아래의 목표 색 왜곡치를 정의한 색 왜곡 임계값이다.

은 목표 색 왜곡에 도달하는 속도를 정의한 피드백 가속 상수로서 플리커나 색 왜곡 조절 속도를 고려하여 실험적으로 정해진다.

는 양수인 상수이다. ACD=

이면

=

이다. ACD>

이면

보다 작아진다. 따라서, ACD가 인지 색 왜곡 수준 보다 커지면 다음 프레임에 적용한 AGP를 낮추어 픽셀 게인을 줄여 데이터의 변조폭을 감소시킨다. here,

is the upper limit gain value (AGP) to be applied to the next frame,

is the upper limit gain value (AGP) of the current frame.

is a color distortion threshold defining a target color distortion value below the perceived color distortion level.

is a feedback acceleration constant that defines the speed at which the target color distortion is reached, and is experimentally determined in consideration of the flicker or color distortion control speed.

is a constant that is positive. ACD=

back side

=

to be. ACD>

back side

becomes smaller Therefore, when the ACD becomes larger than the perceived color distortion level, the AGP applied to the next frame is lowered to reduce the pixel gain to reduce the data modulation width.

Equations 1 to 3 can quantify perceptual color distortion caused by simultaneous contrast between achromatic colors and chromatic colors caused by a difference in stretching rates between achromatic colors and chromatic colors in the RGBW display panel. Here, the stretching ratio is the modulation width of the data modulated by the gain in FIG. 2 . However, this method does not reflect the color luminance perception effect (H-K effect) according to the color gamut difference. If the effect of improving the perceived luminance of chromatic colors according to the color gamut extension is reflected, brighter white can be realized without color distortion in the RGBW display panel.

3A is an input color chart in which various hues and saturation are expressed. FIG. 3B is a color image showing the H-K effect factor showing perceived color luminance when input color chart data as in FIG. 3A is input to the NCG display panel. FIG. 3(C) is a color image showing the H-K effect factor showing perceived color luminance when input color chart data as in FIG. 3(A) is input to the WCG display panel. A method for obtaining the H-K effect factor is a known method, for example, “Simple Estimation Methods for the Helmholtz-Kohlrausch Effect” disclosed in CCC 0361-2317/97/060385-17 (Volume 22, Number 6, December 1997) (the author of the paper: Yoshinobu Nayatani)” can be used.

3 (A) to 3 (C), when the perceived color luminance is calculated for the color chart image as in FIG. 3A using a known H-K effect factor calculation algorithm, the perceived color luminance is It can be seen that Hue) and 　 Saturation are different. Perceived color luminance has a large difference in the same hue (Hue) and saturation (Saturation) according to the color gamut.

Color distortion of RGBW display panels is mainly caused by color contrast between bright achromatic colors and dark chromatic colors. If the perceived luminance of chromatic colors increases due to the H-K effect in WCG, color distortion must be recalculated based on color contrast to realize a brighter image without color distortion in WCG. Since the perceived luminance of chromatic colors increases in WCG, when calculating the perceived color distortion caused by the luminance ratio of chromatic and achromatic colors, it is necessary to reflect the perceived luminance of chromatic colors according to color gamut change. To this end, the present invention calculates the ratio of the H-K effect factor between the WCG and the NCG to obtain the luminance increase rate for each hue in the WCG compared to the NCG. The perceptual luminance increase rate for each color is a method for obtaining the H-K effect factor, for example, “Simple Estimation Methods for the Helmholtz-Kohlrausch Effect (paper)” disclosed in CCC 0361-2317/97/060385-17 (Volume 22, Number 6, December 1997). Author: Yoshinobu Nayatani)”.

FIG. 4B is a diagram showing the increase in perceived color luminance in WCG compared to NCG by calculating the H-K effect factor in each of NCG and WCG with respect to the input color chart image as in FIG. 4A. 3 (A) to 4 (B), the x-axis is the saturation (Saturation), the y-axis is the hue (Hue). Color-coded numbers on the right (0-2) are the perceived luminance ratio.

As can be seen from FIGS. 4A and 4B , it can be seen that the perceived luminance of colors such as red and magenta is almost twice as high in WCG compared to NCG when saturation is high. On the other hand, colors such as cyan, light blue, and yellow have almost no difference in perceived luminance in WCG compared to NCG by about 1 to 1.1 times. Since dark chromatic colors to bright achromatic colors are the cause of increase in color distortion in RGBW display panels, increasing the perceived luminance of chromatic colors when the color gamut is extended to WCG can reduce color distortion in RGBW display panels. In the present invention, in order to quantify the color distortion contribution according to the hue when the color gamut is expanded, the color distortion contribution Wi, which is inversely proportional to the perceived color increase rate, is obtained as shown in FIG. 5B. In FIG. 5A , reference numeral “51” denotes a curve for increasing perceived luminance according to hue in WCG versus NCG. In FIG. 5A , “52” is a color distortion contribution curve showing the degree of color distortion for each hue when the color gamut is extended from NCG to WCG. The color distortion contribution Wi is the color distortion contribution of the i-th pixel and is determined as a value between 0 and 1. The closer Wi is to 1, the greater the color distortion.

When the color distortion contribution is W(i), Equation 2 should be modified to Equation 4. Therefore, the average color distortion (ACD) is proportional to the color distortion contribution W(i) defined as shown in FIG. 5 .

In the present invention, when the color gamut is extended to WCG, as shown in FIG. 5 and Equation 4, the color distortion contribution of the corresponding pixel according to the hue is obtained from each pixel data, and the color distortion contribution is used as the final color distortion weight based on this. According to the present invention, when the color gamut of the RGBW display panel is extended to WCG, the input image is reproduced as a brighter image without color distortion by increasing the pixel gain in a color having a low contribution to color distortion.

In the color distortion compensation algorithm (Comparative Example 1), the RGBW display panel has color distortion due to the luminance contrast between chromatic and achromatic colors. case occurs However, in this method, when the color gamut of the RGBW display panel is extended to WCG, the perceived luminance of chromatic colors is greatly increased, so chromatic colors become brighter and achromatic colors appear relatively darker.

In the present invention, when the color gamut is extended from the RGBW display panel to the WCG, the color distortion (ACD) is calculated as in Equation 4 by reflecting the increase in the perceived luminance of the chromatic colors according to the WCG application. According to the present invention, a brighter image can be realized without color distortion in the RGBW display panel of the WCG color gamut by adjusting the pixel gain in inverse proportion to the color distortion (ACD) calculated as shown in Equation (4). To this end, the present invention adjusts the upper limit gain value (AGP) in FIG. 2 in inverse proportion to the average color distortion (ACD) calculated as in Equation (4). In the present invention, when the average color distortion (ACD) is high, the upper gain value (AGP) is lowered to lower the pixel gain, whereas when the average color distortion (ACD) is lowered, the upper gain value (AGP) is increased. When the RGBW display panel of the WCG color gamut reproduces colors with low average color distortion (ACD), such as red and magenta, by increasing the white luminance, a brighter image can be reproduced without perceived color distortion. . Accordingly, according to the present invention, a brighter image can be displayed without an increase in perceived color distortion in the RGBW display panel of the WCG color gamut, and the effect of reducing power consumption can be increased.

As can be seen from FIG. 5 and Equation 4, when the color gamut is extended to WCG, the color distortion contribution Wi of colors such as red and magenta is cyan or light blue. , lower compared to colors such as yellow. Therefore, in the present invention, in the RGBW display panel of the WCG color gamut, the pixel gain of colors such as red and magenta is applied to the pixel gain of colors such as cyan, light blue, and yellow. higher than that

6 is images of experimental results comparing color distortion and perceived luminance of the present invention and Comparative Example 1 according to color gamut change. 6A is an example in which a sample image is displayed on an RGBW display panel of an NCG color gamut. FIG. 6B is an experimental result image displayed on an RGBW display panel of a WCG color gamut by converting the sample image as shown in FIG. 6A using the color distortion compensation algorithm of Comparative Example 1. FIG. Comparative Example 1 limits the luminance of the achromatic color to be lower than the actual luminance in the RGBW display panel as described above. (C) of FIG. 6 reflects the average color distortion (ACD) according to the hue defined in FIG. 5 and Equation 4 to increase the pixel gain around the color having a low color distortion contribution to increase the achromatic luminance of the pixels. This is an image of the experimental result.

When the present invention is applied to the RGBW display panel of the WCG color gamut, the color distortion is calculated by reflecting the increase in the perceived luminance of chromatic colors according to the WCG application, so the luminance of an achromatic color without color distortion as shown in FIG. can be higher In addition, the present invention calculates the color distortion of each frame by data modulation using Retinex theory, and adjusts the gain to a level at which color distortion is not recognized, thereby individually adjusting the gain of RGB data and the gain of W data. Thus, power consumption can be reduced without perceptual color distortion.

The present invention modulates RGB data by multiplying each of the RGB data by the sum of the frame gain and the pixel gain (FIG. 2). According to the present invention, RGB data may be multiplied by the same gain, or each RGB data may be multiplied by a gain of a different value in consideration of the luminous efficiency of each RGB sub-pixel.

According to the present invention, RGB data may be multiplied by a first gain, multiplied by a second gain in the same manner as the first gain, and W data may be multiplied by a second gain. Each of the first gain and the second gain may be adjusted to an upper limit gain value AGP in FIG. 2 that varies according to the average color distortion (ACD) calculated in FIGS. 5 and 4 .

In the case of LCD, RGB data is multiplied by the same gain, and this gain can be adjusted with average color distortion (ACD) as shown in FIG. 2 . In the case of an OLED display, a second gain among a first gain multiplied by RGB data and a second gain multiplied by W data may be adjusted as an average color distortion (ACD) as shown in FIG. 2 .

In the present invention, as can be seen from FIGS. 2 and 4, the gain of the achromatic color data is relatively larger than the gain of the chromatic data due to the normal color distortion (ACD) proportional to the color distortion contribution (Wi), resulting in average color distortion. When (ACD) increases, the modulation width of the achromatic data becomes larger than that of the chromatic data.

7 is a diagram illustrating in detail a processing procedure of the method for compensating for color gamut and color distortion according to the present invention.

Referring to FIG. 7 , in the method for compensating for color gamut and color distortion of the present invention, the color gamut of the RGBW display panel is extended to WCG and H-K effect factors according to the color gamut extension are calculated ( S01 and S02 ). As the color gamut conversion method, any known algorithm is applicable. For example, the color gamut conversion method may use the method disclosed in Korean Patent Laid-Open No. 10-2011-0005513 (Jan. 18, 2011) proposed by the applicant of the present application. The H-K effect factor calculation method is obtained as shown in FIG. 3C.

The color gamut and color distortion compensation method of the present invention calculates the perceived luminance increase rate (FIG. 4(B)) for each color (hue) in WCGT compared to NCG (S03), and the color distortion contribution curve according to the hue (hue) (FIG. 5 (B)) is generated (S04). S01 to S04 are processed based on pre-experimental results after color gamut conversion of the RGBW display panel. The color distortion contribution curve 52 set in S04 is set as look-up table data. This lookup table is stored in a memory built into the display device of the RGBW pixel structure.

)을 계산하고, 현재 프레임에서 각 픽셀별 게인(

)을 계산한다(S1 및 S2). S1 및 S2의 게인 계산 방법은 본원 발명자들에 의해 제안된 대한민국 공개 특허 10-2014-0081394(2014. 07. 01)에 개시된 방법을 이용할 수 있다. The method for compensating for color gamut and color distortion according to the present invention provides an average (

), and the gain for each pixel in the current frame (

) is calculated (S1 and S2). The method of calculating the gains of S1 and S2 may use the method disclosed in Korean Patent Laid-Open Publication No. 10-2014-0081394 (2014. 07. 01) proposed by the present inventors.

The color gamut and color distortion compensation method of the present invention calculates a hue from each RGB data of an input image for each pixel ( S3 ). A known method may be used for the color calculation method of RGB data. For example, the method of calculating the color of RGB data may use the method disclosed in Korean Patent Laid-Open No. 10-2011-0005513 (Jan. 18, 2011).

In the color gamut and color distortion compensation method of the present invention, an average color distortion (ACD) according to a hue is calculated based on the color distortion contribution curve 52 of FIG. 5 and Equation 4 ( S4 ). Subsequently, in the method for compensating for color gamut and color distortion of the present invention, the upper limit gain value (AGP in FIG. 2) is lowered when the average color distortion (ACD) increases, whereas the upper limit gain value (AGP in FIG. 2) is lowered when the average color distortion (ACD) is lowered. AGP) is increased to realize a bright image without color distortion (S5). Steps S3 to S5 are implemented in a data processing circuit including a lookup table in which color distortion contribution curve data is set, and a logic circuit for processing an operation. This data processing circuit is the same as the data processing unit 110 in FIG. 9 .

The RGBW pixel structure display device to which the method for compensating for color gamut and color distortion of the present invention is applied, as shown in FIG. 8, realizes a bright image without color distortion because the luminance of achromatic colors increases to a level similar to the increase in perceived luminance of chromatic colors. In the example of FIG. 8 , in the WCG color gamut, a white background is set around a red block having a low contribution to color distortion (Wi = 0) and a yellow block having a relatively high contribution to color distortion (Wi = 1). The branch is an example of displaying a sample image on a display device having an RGBW pixel structure. The pixel data of the red block and yellow black of the sample images have the same grayscale, but the perceived luminance is different in WCG and the color distortion contribution (Wi) is different. In this case, since the luminance of achromatic colors is increased to a level similar to the increase in perceived luminance of chromatic colors when the present invention is applied, a white background around a red block with a lower contribution to color distortion compared to an image including a yellow block appears brighter. This is because the average color distortion (ACD) is proportional to the color distortion contribution (Wi), and as shown in FIG. 2 , the gain increases when the average color distortion (ACD) is low, and the increase is larger in achromatic colors. Therefore, if the present invention is applied to a display device having an RGBW pixel structure in a WCG color gamut, the luminance increase amount of an achromatic color is controlled differently for each color in the display device.

9 is a block diagram illustrating a display device according to an embodiment of the present invention. This display device has an RGBW pixel structure in which each pixel is divided into three sub-pixels each displaying primary color data and one sub-pixel displaying white data.

Referring to FIG. 9 , the display device of the present invention includes a data processing unit 110 , driving units 102 , 104 , driving units 102 , 104 , 108 , and a display panel 100 . The drivers 102 , 104 , and 108 transmit input data modulated by the data processor 104 to pixels of the display panel 100 including the timing controller 108 , the data driver 102 , and the gate driver 104 . Fill in. The data processing unit 110 may be embedded in the timing controller 108 .

The data processing unit 110 sets the achromatic luminance of the first pixel displaying the first color to higher than the achromatic luminance of the second pixel displaying the second color in the first and second colors having the same grayscale. The data is modulated by increasing the gain of the data to be written higher than the gain of the data to be written into the second pixel. The data processing unit 110 converts the RGB data into RGBW data to match the WCG color gamut, and adjusts the gain according to the hue based on the color distortion contribution curve 52 set in S04 of FIG. 7 and Equation 4 . The data processing unit 110 processes steps S3 to S5 in FIG. 7 using a lookup table and a logic circuit. The lookup table is stored in the memory of the data processing unit 110 . In the case of pixel data of a color having a low color distortion contribution Wi, the upper limit gain value (AGP in FIG. 2 ) rises, so that the achromatic luminance becomes higher. The luminance of the achromatic color may be gradually increased as the saturation decreases as shown in FIG. 2 along a straight line connecting the frame gain k and the AGP, that is, as the achromatic color approaches. Each of the frame gain and the pixel gain may include a first gain for modulating RGB data and a second gain for modulating W data in consideration of luminous efficiency of each RGBW sub-pixel. Due to the data processing unit 110 , the achromatic luminance may be different for each color in the same grayscale. For example, when the contribution of color distortion Wi of the first color is smaller than that of the second color in the first and second color data of the same grayscale, the achromatic luminance of the pixel displaying the first color is displayed as the second color. It may be higher than the luminance of the achromatic color of the corresponding pixel.

The timing controller 108 generates and outputs a data control signal and a gate control signal that respectively control driving timings of the data driver 102 and the gate driver 104 , and outputs data modulated by the data processing unit 110 . It is transmitted to the data driver 102 . The timing controller 108 controls the driving timing of the data driver 102 and the driving timing of the gate driver 104 using the timing synchronization signals Vsync, Hsync, DE, and CLK input from the outside. It is possible to generate a gate control signal to control.

The data driver 102 converts digital data received from the timing controller 108 into an analog data signal in response to a data control signal from the timing controller 108 and supplies it to data lines of the display panel 100 . The data driver 102 subdivides the gamma voltage set from the gamma voltage generator (not shown) into gradation voltages respectively corresponding to gradation values of the data, and then converts digital data into analog data signals using the subdivided gradation voltages. convert The data driver 12 may include at least one source drive IC. The source drive IC is mounted on a circuit film such as TCP, COF, FPC, etc. and attached to the display panel 100 by a Tape Automatic Bonding (TAB) method, or on a substrate of the display panel 100 by a COG (Chip On Glass) method. It can be mounted directly.

The gate driver 104 sequentially drives a plurality of gate lines of the display panel 100 in response to a gate control signal from the timing controller 108 . The gate driver 104 supplies a scan pulse (or gate pulse) of a gate-on voltage to each gate line in a corresponding scan period in response to the gate control signal to the gate lines (or scan lines) of the display panel 100 , , a gate-off voltage is supplied during the remaining period. The gate driver 14 is composed of at least one gate IC and is mounted on a circuit film such as a Tape Carrier Package (TCP), Chip On Film (COF), Flexible Print Circuit (FPC), etc. Automatic Bonding) method or may be mounted on the display panel 100 by COG (Chip On Glass) method. In addition, the gate driver 14 may be embedded in the display panel 100 in a GIP (Gate In Panel) method and formed on the thin film transistor substrate together with the pixel array.

The display panel 100 includes a pixel array in which data lines and gate lines cross and pixels are arranged in a matrix form. The display panel 100 is an RGB display panel in which each of the pixels is divided into RGBW sub-pixels. The display panel 100 may be a display panel of an OLED display device or a display panel of an LCD.

When an OLED panel is used as the display panel 100 , each of the RGBW sub-pixels includes an OLED element connected between a high-potential power line and a low-potential power line, and a pixel circuit connected to a data line and a gate line and driving the OLED element. to provide The pixel circuit includes at least a switching transistor and a driving transistor and a storage capacitor. The switching transistor charges the storage capacitor with a voltage corresponding to the data signal from the data line in response to the scan pulse from the gate line, and the driving transistor controls the current supplied to the OLED device according to the voltage charged in the storage capacitor to control the OLED. Controls the amount of light emitted by the device. The amount of light emitted from the OLED device is proportional to the current supplied from the driving transistor.

When a liquid crystal panel is used as the display panel 100 , the display panel 100 includes a color filter substrate on which a color filter array is formed, a thin film transistor substrate on which a thin film transistor array is formed, and a liquid crystal layer between the color filter substrate and the thin film transistor substrate. and a polarizing plate attached to the outer surfaces of the color filter substrate and the thin film transistor substrate, respectively. Each pixel realizes a desired color by a combination of RGBW sub-pixels that control light transmittance by varying the liquid crystal arrangement according to the data signal. Each sub-pixel includes a thin film transistor connected to a gate line and a data line, a capacitance of a liquid crystal cell connected in parallel with the thin film transistor, and a storage capacitor. The liquid crystal cell charges the difference voltage between the data signal supplied to the pixel electrode through the thin film transistor and the common voltage supplied to the common electrode, and drives the liquid crystal according to the charged voltage to control light transmittance. The storage capacitor stably maintains the voltage charged in the liquid crystal cell. The liquid crystal is driven by a vertical electric field, such as a twisted nematic (TN) mode or a vertical alignment (VA) mode, or is driven by a horizontal electric field, such as an in-plane switching (IPS) mode or a fringe field switching (FFS) mode.

FIG. 10 is a block diagram illustrating the data processing unit shown in FIG. 9 in detail.

Referring to FIG. 10 , the data processing unit 110 includes a data conversion unit 112 , a data modulation unit 114 , a color distortion calculation unit 116 , and a gain calculation unit 118 .

The data converter 112 converts RGB data into RGBW data to match the WCG color gamut. As an example of the RGBW data conversion method, W data is generated by converting a minimum value among input RGB data into W data, and the RGB data is modulated by subtracting the minimum value (W data) from each of the input RGB data. As the RGBW data conversion method, any known method is applicable. As an example, the RGBW data conversion method may use a method disclosed in Korean Patent Application Laid-Open No. 10-2002-0013830, Korean Patent Application Laid-Open No. 10-2004-0083786, and the like.

The color distortion calculator 116 calculates an average color distortion proportional to the color distortion contribution of the input color using a preset color distortion contribution curve 52 and a preset color distortion calculation algorithm (Equation 4). The color distortion calculator 116 calculates an average color distortion (ACD) reflecting the color distortion contribution in WCG using the color distortion contribution curve 52 set as the lookup table data and Equation (4).

The gain calculator 118 adjusts the gain to a value inversely proportional to the average color distortion (ACD). The gain calculator 118 increases the achromatic luminance by increasing the upper limit gain (AGP of FIG. 2 ) in pixel data of a color having a small average color distortion (ACD). On the other hand, the gain calculator 118 lowers the achromatic luminance by lowering the upper limit gain (AGP of FIG. 2 ) in pixel data of a color having a large average color distortion (ACD). The gain is the sum of the frame gain and the pixel gain. When the upper limit gain value (AGP in Fig. 2) is adjusted, the frame gain value is fixed and the pixel gain value is adjusted. The gain may be divided into a first gain multiplied by RGB data and a second individual multiplied by W data.

The data modulator 114 modulates the data by multiplying the data for each pixel by the gain input from the gain calculator 118 . The data modulator 114 multiplies the gain input from the gain calculator 118 by the input data RGBW, modulates the data (R'G'B'W') and transmits it to the data driver 102 .

Those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Accordingly, 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.

51: Perceptual luminance increase curve 52: Color distortion contribution curve
100: display panel 102: data driver
104: gate driver 108: timing controller
110: data processing unit 112: data conversion unit
114: data modulator 116: color distortion calculator
118: gain calculation unit

Claims (11)

a wide color gamut display panel including three sub-pixels each displaying primary color data and one sub-pixel displaying white data, in which data lines and gate lines cross each other and pixels arranged in a matrix form;
Data to be written in the first pixel such that, in the first and second colors having the same grayscale, the achromatic luminance of the first pixel displaying the first color is higher than the achromatic luminance of the second pixel displaying the second color a data processing unit that modulates the data by increasing a gain of , higher than a gain of data to be written into the second pixel; and
and a driver configured to write data modulated by the data processor to the pixels. The method of claim 1,
The first color has a lower color distortion contribution than the second color in a wide color gamut. 3. The method of claim 2,
The data processing unit,
a data conversion unit that converts RGB data into RGBW data of a wide color gamut;
a color distortion calculator configured to calculate a color distortion proportional to a color distortion contribution of an input color using a preset color distortion contribution curve and a preset color distortion calculation equation;
a gain calculator for adjusting the gain to a value inversely proportional to the color distortion; and
and a data modulator for modulating the data by multiplying the data by the gain for each pixel. 4. The method according to any one of claims 1 to 3,
When a first image including the block of the first color and a white background and a second image including the block of the second color and the white background are displayed on the display panel
a display device in which a white background luminance of the first image is higher than a white background luminance of the second image. A wide color gamut having a display panel including three sub-pixels each displaying primary color data and one sub-pixel displaying white data, in which data lines and gate lines intersect and pixels arranged in a matrix form, respectively A method of driving a display device, comprising:
Data to be written in the first pixel such that, in the first and second colors having the same grayscale, the achromatic luminance of the first pixel displaying the first color is higher than the achromatic luminance of the second pixel displaying the second color modulating the data by increasing a gain of , higher than a gain of data to be written into the second pixel; and
and writing modulated data into the pixels. 6. The method of claim 5,
The method of driving a display device, wherein the first color has a lower color distortion contribution than the second color in a wide color gamut. 7. The method of claim 6,
The step of modulating the data includes:
converting RGB data into RGBW data of a wide color gamut;
calculating color distortion proportional to the color distortion contribution of the input color using a preset color distortion contribution curve and a preset color distortion calculation formula;
adjusting the gain to a value inversely proportional to the color distortion; and
and modulating the data by multiplying the data by the gain for each pixel. 8. The method according to any one of claims 5 to 7,
When a first image including the block of the first color and a white background and a second image including the block of the second color and the white background are displayed on the display panel
A method of driving a display device, wherein the white background luminance of the first image is higher than the white background luminance of the second image. A wide color gamut having a display panel including three sub-pixels each displaying primary color data and one sub-pixel displaying white data, in which data lines and gate lines intersect and pixels arranged in a matrix form, respectively A method of driving a display device, comprising:
calculating a perceived luminance increase rate for each color (hue) according to the color gamut extension of the display panel, and generating a color distortion contribution curve according to the color based on the perceived luminance increase rate;
Average of gains for each pixel in the previous frame (

), and the gain for each pixel in the current frame (

) to calculate;
calculating a color from each RGB data of the input image for each pixel;
calculating an average color distortion proportional to the color distortion contribution by using the color distortion contribution curve and a preset color distortion calculation formula;
adjusting a gain to a value inversely proportional to the average color distortion; and
and modulating the data by multiplying the gain by the data of the input image for each pixel. 10. The method of claim 9,
The average color distortion (ACD) is
When the color distortion contribution is W(i) and the total number of pixels is N

A method of driving a phosphorus display device. 11. The method of claim 10,
The step of adjusting the gain is
When the average color distortion increases, the upper limit gain value is lowered, whereas when the average color distortion decreases, the upper limit gain value is increased.

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