KR102385628B1 - Display device and method for driving the same - Google Patents

Abstract

The present application is to provide a display device capable of mitigating recognition of a logo area as an afterimage, and detects an edge area corresponding to the outline of a predetermined mark fixedly displayed over a threshold period among the display area based on an image signal, , A display device comprising a logo area processing unit that calculates a saturation correction value for the chroma value of each pixel in the edge region based on a preset correction coefficient, and generates a correction signal for the image signal based on the chroma correction value do. Since the logo area processing unit generates a correction signal that reduces only the luminance of the edge area, which has relatively low visibility among the logo area, compared to the image signal, it is possible to alleviate the recognition of the logo area as an afterimage while preventing the image processing for this from being recognized. can be

Description

Display device and driving method thereof

The present application relates to an apparatus for displaying an image and a driving method thereof.

As we enter the information age in earnest, the field of display for visually displaying electrical information signals is rapidly developing. In addition, research to develop performance such as thinness, light weight, and low power consumption for various display devices is continuing.

Representative examples of the display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescence display device (Electro Luminescence). display device: ELD), electro-wetting display device (EWD), organic light emitting display device (OLED), and the like.

Such a display device includes a pair of substrates and a unique light emitting material or a polarizing material disposed therebetween. The display device includes a plurality of pixels defined in a display area for displaying an image, and drives the plurality of pixels so that the plurality of pixels emit light having respective colors or luminances, thereby displaying an image.

On the other hand, some image signals may include a logo that is fixedly disposed in some areas of the display area for a predetermined time or longer.

For example, as shown in FIG. 1 , a logo may be inserted into the image as a cover for indicating the producer and title of the image. In addition, the logo inserted into the image is fixedly arranged in some areas of the display area.

However, pixels in the display area except for the area where the logo is placed (hereinafter referred to as "logo area") display the color or luminance that changes according to the screen change, whereas the pixels in the logo area are related to the screen change. The same color and luminance should be displayed without

On the other hand, in the case of an organic light emitting display device, since an image is displayed using an organic light emitting device, which is a self-luminous device, a separate light source is unnecessary. and 1000 times or more faster reaction speed, so there is an advantage in that there are few afterimages.

However, there is a problem in that the organic layer of the organic light emitting device is easily deteriorated due to various causes. In particular, as a high driving current is supplied to the organic layer for a long period of time, there is a problem in that the deterioration of the organic layer is increased.

However, since pixels of the logo area are driven to display the same luminance and color for a long period of time, the organic light emitting device included in each pixel of the logo area receives greater stress than the remaining areas except for the logo area.

Accordingly, there is a problem in that the organic light emitting device of the logo area is deteriorated more than other organic light emitting devices of the remaining area except for the logo area. Accordingly, there is a problem in that a logo area of a previously displayed image may be recognized as an afterimage even when another image is subsequently displayed, and thus the lifespan of the organic light emitting display device is shortened or terminated.

The present application provides a display device capable of mitigating recognition of a logo area as an afterimage and a driving method thereof.

In order to solve the above problems, the present application provides a panel unit including a plurality of pixels defined in a display area displaying an image signal, and the outline of a predetermined mark fixedly displayed over a threshold period in the display area based on the image signal. A logo area processing unit that detects a corresponding edge region, calculates a chroma correction value for the chroma value of each pixel in the edge region based on a preset correction coefficient, and generates a correction signal for the image signal based on the chroma correction value and a control unit for driving the panel unit based on the correction signal.

Here, the logo area processing unit includes a logo area detection unit that detects a logo area corresponding to a predetermined mark fixedly displayed over a threshold period based on the video signal, an edge area detection unit that detects an edge area among the logo areas, and a correction coefficient based on the Thus, the chroma correction unit for calculating the chroma correction value for the chroma value of each pixel in the edge region, based on the chroma correction value for each pixel in the edge region, calculates the gradation correction value for each pixel in the edge region. and a gradation value correcting unit, and a correction signal generating unit generating a correction signal based on the gradation correction value for each pixel in the edge region.

The correction coefficient is a rational number between 0 and 1, and the chroma correction unit calculates a product of the chroma value for each pixel in the edge region and the correction coefficient as the saturation correction value for each pixel in the edge region. The gradation correction unit calculates a gradation correction value based on the chroma correction value and the minimum value, and the correction signal generator selects, for each pixel in the edge region, at least one of the gradation values of red, green, and blue that is equal to or greater than the gradation correction value. A correction signal is generated by substituting it with a gradation correction value.

The logo area processing unit may further include a peak area detection unit configured to detect a partial area having a width equal to or less than a threshold width among edge areas as a peak area. In this case, the chroma correction unit calculates a chroma correction value for the chroma value of each pixel in the region other than the peak region of the edge region based on the first correction coefficient, and sets the value to the second correction coefficient smaller than the first correction coefficient. Based on the chroma correction value for the chroma value of each pixel in the peak region, a chroma correction value is calculated.

In addition, the present application includes the steps of detecting a logo area corresponding to a predetermined mark fixedly displayed over a threshold period in the display area based on the image signal, detecting an edge area corresponding to the outline of the cover in the logo area, calculating a chroma correction value for the chroma value of each pixel in the edge region based on a set predetermined correction coefficient; A display device comprising: calculating a value; generating a correction signal for an image signal based on a gradation correction value for each pixel in an edge region; and driving a plurality of pixels based on the correction signal It further provides a driving method of

A display device according to an exemplary embodiment of the present application detects an edge region corresponding to the outline of a predetermined mark in a display region based on an image signal, and provides a saturation value of each pixel in the edge region based on a preset correction coefficient. and a logo area processing unit that calculates a correction value and generates a correction signal for the image signal based on the chroma correction value.

Specifically, the logo area processing unit does not correct the image signal for the entire logo area, but corrects the image signal for the edge area corresponding to the outline of the logo having relatively low visibility among the logo area.

If image processing is performed to reduce the luminance of the entire logo area compared to the image signal, since the logo area is displayed darkly, the image processing is visually recognized, and thus the image quality can be reduced.

Accordingly, in the logo area processing unit according to each embodiment of the present application, the logo area processing unit does not reduce the luminance of the entire logo area compared to the image signal, but only the luminance of the edge area with relatively low visibility among the logo area, rather than the image signal. to generate a correction signal. Therefore, while it is possible to alleviate the recognition of the logo area as an afterimage, image processing for this can be prevented from being recognized.

Then, the logo area processing unit calculates a saturation correction value for the saturation value of each pixel in the edge area based on a preset correction coefficient. In this case, since the correction coefficient is a rational number between 0 and 1, the chroma correction value is calculated as a value lower than the chroma value. Then, the logo area processing unit calculates a gradation correction value for each pixel in the edge region based on the saturation correction value of each pixel in the edge region, and for each pixel in the edge region, a gradation among red, green, and blue gradation values. At least one larger than the correction value is substituted with the gradation correction value. That is, the logo area processing unit generates a correction signal for reducing the difference between red, green, and blue grayscale values for each pixel of the edge area.

If the respective grayscale values of red, green, and blue are decreased by the same ratio for each pixel in the edge region, the difference between the red, green, and blue grayscale values is maintained, and eventually the red, green, and blue sub-pixels are deteriorated. Since the difference is maintained as it is, the color or luminance difference may be recognized as an afterimage.

Accordingly, the logo area processing unit according to each embodiment of the present application sets at least one of red, green, and blue gray values higher than the gray level correction value for each pixel in the edge area with relatively low visibility in the logo area as the gray level correction value. Reduce. Accordingly, a difference in lifetime between the red, green, and blue sub-pixels corresponding to each pixel in the edge region may be alleviated.

In addition, the logo area processing unit may further include a peak area detection unit that detects a peak area less than a threshold width among edge areas. Here, the peak area has a width that is small enough not to affect the overall shape of the logo. In this case, the chroma correction unit calculates a chroma correction value of each pixel in the remaining region except for the peak region of the edge region based on the first correction coefficient, and based on the second correction coefficient lower than the first correction coefficient, in the edge region A saturation correction value of each pixel in the peak region is calculated.

That is, the chroma correction unit calculates a chroma correction value for each pixel in a peak region having relatively low visibility, based on the second correction coefficient lower than the first correction coefficient. Accordingly, the gradation correction value of each pixel in the peak region is reduced by a larger decrease compared to the gradation correction value of each pixel in the remaining region except for the peak region among the edge regions.

Accordingly, since each pixel in the peak region of the edge region displays a lower luminance than each pixel in the remaining regions except for the peak region, deterioration of the pixel may be further alleviated. In addition, since the peak area has low visibility, even if the peak area is corrected to be darker, image processing for the logo area can be prevented from being recognized.

1 is a view showing different frames in an image in which a logo is inserted.
2 is a block diagram illustrating a display device according to a first embodiment of the present application.
3 is an equivalent circuit diagram of each sub-pixel of an organic light emitting diode display.
4 is a block diagram illustrating the logo area processing unit of FIG. 2 according to the first embodiment of the present application.
5 is a flowchart illustrating a method of driving a display device according to a first exemplary embodiment of the present application.
6A is a diagram illustrating a logo area in the image of FIG. 1 .
FIG. 6B is a diagram illustrating an example of an edge area among the logo areas of FIG. 6A .
FIG. 6C is an enlarged view of pixels on a first line in area A of FIG. 6A .
7 is a block diagram illustrating the logo area processing unit of FIG. 3 according to the second embodiment of the present application.
8 is a flowchart illustrating a method of driving a display device according to a second exemplary embodiment of the present disclosure.
FIG. 9A is a diagram illustrating an example of a peak region among the edge regions of FIG. 6B .
FIG. 9B is an enlarged view of pixels on a first line in area A' of FIG. 6A .

Hereinafter, a display device and a driving method thereof according to each embodiment of the present application will be described in detail with reference to the accompanying drawings.

First, a display device and a driving method thereof according to a first exemplary embodiment of the present application will be described with reference to FIGS. 2 to 8 .

2 is a block diagram illustrating a display device according to a first embodiment of the present application. 3 is an equivalent circuit diagram of each sub-pixel of an organic light emitting diode display. 4 is a block diagram illustrating the logo area processing unit of FIG. 2 according to the first embodiment of the present application. 5 is a flowchart illustrating a method of driving a display device according to a first exemplary embodiment of the present application. 6A is a diagram illustrating a logo area in the image of FIG. 1 . FIG. 6B is a diagram illustrating an example of an edge area among the logo areas of FIG. 6A . And FIG. 6C is an enlarged view of the pixels of the first line in area A of FIG. 6A .

As shown in FIG. 2 , the display device 100 according to the first embodiment of the present application includes a panel unit 110 including a plurality of pixels P defined in a display area displaying an image signal, and based on the image signal. to detect an edge region corresponding to the outline of a predetermined mark that is fixedly displayed for a threshold period or longer in the display region, and calculates a chroma correction value for the chroma value of each pixel in the edge region based on a preset correction coefficient, It includes a logo area processing unit 120 for generating a correction signal for the image signal based on the correction value, and a controller 130 for driving the panel unit 110 based on the correction signal.

In addition, the display device 100 includes a gate driver (GDR) 140 driving the gate line GL of the panel unit 110 and a data driver driving the data line DL of the panel unit 110 . (Data Driver: DDR) 150 may be further included.

The panel unit 110 includes a plurality of pixels P defined in the display area. Each pixel P may include sub-pixels R, G, and B that emit red, green, and blue light.

As shown in FIG. 3 , when the display device 100 is an organic light emitting display device, each of the sub-pixels R, G, and B includes a switch transistor T1, a storage capacitor Cst, a driving transistor T2 and It may include an organic light emitting diode (OLED).

The switch transistor T1 includes a gate electrode connected to the gate line GL, and first and second electrodes connected between the data line DL and the first node n1 . The first node n1 is connected to the gate electrode of the storage capacitor Cst and the driving transistor T2.

The switch transistor T1 is turned on based on the gate signal of the gate line GL, and the data signal of the data line DL through the turned-on switch transistor T1 is transmitted to the first node n1, that is, the driving transistor. It is supplied to the gate electrode of (T2) and the storage capacitor (Cst).

The storage capacitor Cst is connected between the first node n1 and the second node n2. The second node n2 is a node between the driving transistor T2 and the organic light emitting diode OLED.

The storage capacitor Cst is filled with the data signal of the data line DL supplied to the first node n1 through the turned-on switch transistor T1. Then, the voltage charged in the storage capacitor Cst is supplied to the gate electrode of the driving transistor T2. That is, the channel of the driving transistor T2 is adjusted according to the voltage charged in the storage capacitor Cst, so that the intensity of the driving current supplied to the organic light emitting device OLED is adjusted.

The driving transistor T2 includes a gate electrode connected to the first node n1 and first and second electrodes connected in series to the organic light emitting diode OLED between the first and second power lines VDD and VSS. includes

The driving transistor T2 is turned on based on a signal charged in the first node n1. In addition, a current path is generated between the first and second power lines VDD and VSS through the turned-on driving transistor T2 , and the driving current is supplied to the organic light emitting diode OLED.

Again, Fig. 2 will be described next.

The logo area processing unit 120 generates a correction signal CS for the image signal of the logo area based on the image signal IMAGE and a preset correction coefficient.

Specifically, the logo area processing unit 120 detects an edge area corresponding to the outline of a predetermined mark in the display area based on the image signal, and the saturation value of each pixel of the edge area based on a preset correction coefficient. A correction value is calculated, and a correction signal is generated based on the chroma correction value. The logo area processing unit 120 will be described in more detail below with reference to FIG. 4 .

The TIMING CONTROLLER (TC) 130 generates a control signal for driving the panel unit 110 based on the image signal IMAGE supplied from the outside or the correction signal CS supplied from the log area processing unit 120 . create

Although not specifically shown in FIG. 2, the controller 130 controls not only the image signal IMAGE or the correction signal CS, but also a timing signal supplied from an external system, that is, a vertical sync signal, a horizontal sync signal, and a data enable signal. Further, the gate control signal GCS for controlling the operation of the gate driver 140 and the data control signal DCS for controlling the operation of the data driver 150 are generated.

The gate driver 140 drives the gate line GL of the panel unit 110 based on the gate control signal GCS, and the data driver 150 drives the panel unit 110 based on the data control signal DCS. 110) drives the data line DL. Accordingly, an image corresponding to the image signal IMAGE or the correction signal CS is displayed on the panel unit 110 .

As shown in FIG. 4 , the logo area processing unit 120 detects a logo area corresponding to a predetermined mark fixedly displayed over a threshold period among the display areas based on the image signal IMAGE. , an edge region detection unit 122 that detects an edge region corresponding to the outline of the cover among the logo regions, and a chroma correction unit that calculates a chroma correction value for the chroma value of each pixel in the edge region based on a preset correction coefficient ( 123), the gradation value correction unit 124 that calculates a gradation correction value for each pixel of the edge region based on the chroma correction value for each pixel of the edge region, and the gradation correction value for each pixel in the edge region. , a correction signal generating unit 125 for generating a correction signal for the image signal of the logo area.

And, as shown in FIG. 5, the method of driving the display device according to the first embodiment of the present application includes the step of detecting a logo area corresponding to the mark in a fixed period among the display areas based on the image signal (S10) , detecting an edge region corresponding to the outline of the cover among the logo regions (S20), calculating a chroma correction value for the chroma value of each pixel of the edge region based on a preset correction coefficient (S30), saturation generating a gradation correction value for each pixel in the edge region based on the correction value (S40), generating a correction signal for the image signal based on the gradation correction value for each pixel in the edge region (S50), and and driving a plurality of pixels based on the correction signal ( S60 ).

The logo area detection unit 121 detects a logo area in which a logo is fixedly displayed over a threshold time at a specific position among the display areas displaying an external image signal IMAGE. (S10)

For example, the logo area detection unit 121 detects red, green, and blue grayscale values for each of the plurality of pixels in each frame of the external image signal IMAGE. In addition, by comparing frames corresponding to the threshold period, pixels having respective grayscale values of red, green, and blue within a predetermined error range in the frame of the threshold period may be detected as the logo area.

The edge region detection unit 122 detects an edge region corresponding to the outline of the logo among the logo regions. (S20) In this case, the edge region detection unit 122 may detect the edge region using a general outline detection mask. For example, the edge region detection unit 122 may detect the edge region using any one of Sobel, Prewitt, and Roberts cross masks.

For reference, the Sobel mask is a representative differential operator when detecting an edge region, and it differentiates once on the x-axis and y-axis, respectively, and has the characteristic of detecting diagonal edge components more sensitively than horizontal and vertical edge components. . The Prewitt mask is virtually identical to the Sobel mask except that the specific gravity values of the mask are different, and has the advantage of faster calculation speed than the Sobel mask. The Roberts cross mask has a shape with a 45 degree inclination, and has the advantage of detecting clear contours and the calculation speed is faster than the Sobel mask and Prewitt mask, but has the disadvantage of being very sensitive to noise.

For example, the edge region detector 122 calculates a brightness value corresponding to each of red, green, and blue grayscale values for each pixel of the logo region based on the image signal IMAGE. Here, the brightness value of each pixel may be an average value of the red gradation value R, the green gradation value G, and the blue gradation value B as shown in Equation 1 below.

In Equation 1, I is an intensity value, R is a red gradation value, G is a green gradation value, and B is a blue gradation value. As shown in Equation 1, the brightness value may be replaced with an average value of grayscale values of red, green, and blue.

In addition, the edge region detection unit 122 uses the contour detection mask to edge pixels having a brightness value I among pixels in the logo region different by more than a threshold difference compared to neighboring pixels corresponding to a predetermined mask region. area can be detected.

The chroma correction unit 123 calculates a chroma correction value for the chroma value of each pixel in the edge region. (S30)

First, the chroma correction unit 123 calculates a chroma value for each pixel in the edge region. For example, the saturation value of each pixel may be calculated as in Equation 2 below.

In Equation 2, S is the saturation, MIN(R, G, B) is the minimum value among the red gradation value (R), the green gradation value (G), and the blue gradation value (B), and MAX (R, G, B) is the maximum value among the red gradation value R, the green gradation value G, and the blue gradation value B.

As shown in Equation 2, the saturation value correcting unit 123 sets the minimum value (MIN(R, G, B)) and the maximum value (MAX(R, G,B)), and the ratio (MIN(R,G,B)/MAX(R, G, B)) is subtracted from 1 and the remainder is calculated as the saturation value (S).

Next, the chroma correction unit 123 calculates a chroma correction value for the chroma value S of each pixel in the edge region based on a preset correction coefficient.

Here, the correction factor is a rational number between 0 and 1. In addition, the saturation correction value may be defined as a product of the saturation value S of each pixel and a correction coefficient. Accordingly, the chroma correction value for the chroma value S of each pixel is calculated as a value smaller than the chroma value S.

The gray level correction unit 124 calculates a gray level correction value of each pixel of the edge area based on the saturation correction value of each pixel of the edge area. (S40)

As shown in Equation 3, the gray level correction unit 124 calculates the maximum value (MAX(R,G) of Equation 2 based on the saturation correction value S_C and the minimum value MIN(R,G,B)). ,B)), a grayscale correction value (MAX_C) is calculated.

The correction signal generator 125 generates a correction signal for the image signal based on the grayscale correction value of each pixel of the edge region. (S50)

Specifically, the correction signal generator 125 sets at least one of the red, green, and blue gray values R, G, and B that is equal to or greater than the gray level correction value MAX_C to the gray level correction value ( MAX_C) to generate a correction signal CS.

Thereafter, the control unit 130 drives the plurality of pixels P provided in the panel unit 110 based on the correction signal CS supplied from the logo area processing unit 120 . (S60)

Hereinafter, a method of driving the display device according to the first embodiment of the present application will be described using the logo area of FIG. 1 as an example.

The logo area detection unit 121 detects pixels in the image signal of FIG. 1 , in which the gradation value of each color remains the same within an error range for a threshold time. Here, the error range means a preset equivalent or equivalent range. Accordingly, as shown in FIG. 6A , a logo area (“Logo” in FIG. 1) is detected. (S10)

The edge region detection unit 122 detects the edge region as shown in FIG. 6B by applying an outline filter mask to the logo region of FIG. 6A . (S20)

The saturation value correction unit 123 calculates a saturation correction value for the saturation value of each pixel in the edge region. (S30)

In detail, pixels on the first line among regions A shown in FIGS. 6A and 6B will be described as examples. For ease of explanation, it is assumed that the color of each pixel P is represented by a combination of red, green, and blue, each comprising 256 grayscale values.

Table 1 below shows red, green, and blue grayscale values (R, G, B) for each pixel AP1 to AP19 of the first line among regions A shown in FIGS. 6A and 6B, respectively, according to Equation 1 The INTENSITY of each pixel AP1 to AP19 and the saturation value SATURATION of each pixel AP3 to AP7 and AP12 to AP18 of the edge region according to Equation 2 are shown. For reference, in Table 1, the brightness value (INTENSITY) is indicated to two decimal places, and the saturation value (SATURATION) is indicated to the third decimal place.

Referring to FIG. 6B , it is assumed that pixels of the edge region detected by the edge region detection unit 122 are AP3 to AP7 and AP12 to AP18, as indicated by shades in Table 1 . Exemplarily, as shown in Table 1, the edge region detector 122 may detect a pixel having a difference in brightness value of 3 or more from at least one of the pixels adjacent to the left and right as the edge region.

Subsequently, as shown in Table 2 below, the saturation value correcting unit 123 corresponds to the saturation value SATURATION of each of the pixels AP3 to AP7 and AP12 to AP17 of the edge region based on the preset correction coefficient. A correction value S_C is calculated. (S30) As mentioned above, the correction factor is a rational number between 0 and 1. Illustratively, in the example of Table 2, it is assumed that the correction factor is 0.8.

As shown in Table 3 below, the grayscale correction unit 124 calculates the grayscale correction value MAX_C based on the saturation correction value S_C of each pixel AP3 to AP7 and AP12 to AP18 of the edge region. do. (S40)

That is, as shown in Equation 3 above, the grayscale value correcting unit 124 applies the red, green, and blue grayscale values R, G, Among B), a grayscale correction value MAX_C corresponding to the minimum value MIN(R,G,B) and the chroma correction value S_C is calculated.

Next, the correction signal generator 125 generates the correction signal CS based on the grayscale correction value MAX_C of each of the pixels AP3 to AP7 and AP12 to AP18 of the edge region. (S50)

As shown in Table 4 below, the correction signal generating unit 125 generates red, green, and blue grayscale values (R, G, B) for each pixel (AP3 to AP7, AP12 to AP18) of the edge region. The correction signal CS is generated by replacing at least one of the grayscale correction values MAX_C or higher with the grayscale correction value MAX_C. For reference, the gray level correction value (MAX_C) of Table 4 is a value obtained by rounding the gray level correction value (MAX_C) of Table 3 to the first decimal place.

That is, taking the AP3 pixel among the pixels AP3 to AP7 and AP12 to AP18 of the edge region as an example, each of the red, green, and blue grayscale values R, G, and B for the AP3 pixel according to the image signal IMAGE. ) is (212, 156, 6), and accordingly, the grayscale correction value MAX_C is calculated as 27. Accordingly, when the red and green gray values R and G greater than the gray level correction value MAX_C are replaced with the gray level correction value MAX_C, red, green, and blue for the AP3 pixel according to the correction signal CS, respectively The grayscale values (R, G, B) of ( 27 , 27 , 6) are generated.

Thereafter, the control unit 130 drives the panel unit 110 based on the correction signal CS generated by the correction signal generating unit 125 . (S60)

As described above, according to the first embodiment of the present application, the correction signal CS is generated by correcting at least one grayscale value among red, green, and blue for each pixel in the edge region corresponding to the outline of the logo in the logo region. create As such, image processing for the logo area is not performed on the entire logo area, but only on the edge area with relatively low visibility among the logo areas. Therefore, while the afterimage due to the logo area can be improved, it can be prevented that the entire logo area is displayed with low luminance as a whole, thereby preventing image processing of the logo area from being recognized.

Then, the logo area processing unit 120 calculates a saturation correction value for the chroma value of each pixel of the edge region based on a preset correction coefficient, and each of the edge regions based on the chroma correction value of each pixel in the edge region. A gradation correction value for the pixel is calculated, and a correction signal is generated based on the gradation correction value of each pixel in the edge region. At this time, the logo area processing unit 120 generates a correction signal by replacing at least one of the red, green, and blue grayscale values greater than the grayscale correction value with the grayscale correction value for each pixel of the edge region.

That is, the logo area processing unit 120 does not generate a correction signal by replacing each of the red, green, and blue grayscale values with values reduced by the same ratio for each pixel of the edge area, but rather of each pixel of the edge area. A correction signal is generated by replacing at least one of red, green, and blue grayscale values with a grayscale correction value based on the grayscale correction value according to the saturation correction value.

In other words, the logo area processing unit 120 generates a correction signal for reducing the difference between red, green, and blue grayscale values for each pixel of the edge area. Therefore, the difference in deterioration of the red, green, and blue sub-pixels R, G, and B corresponding to each pixel P of the edge region can be alleviated by the correction signal CS by the logo region processing unit 120 . Thereby, the difference in lifetimes of the red, green, and blue sub-pixels R, G, and B may be alleviated.

In other words, the logo area processing unit 120 does not generate a correction signal for the entire logo area, but generates a correction signal for an edge area corresponding to the outline of the logo having relatively low visibility among the logo areas. Accordingly, since the luminance of the logo area is not reduced as a whole, image processing for preventing an afterimage caused by the logo area can be prevented from being recognized.

Then, by the correction signal CS by the logo area processing unit 120, the grayscale values reduced by a differential ratio are displayed so that the red, green, and blue sub-pixels included in each pixel of the edge area have similar grayscale values to each other. do. Accordingly, while the afterimage caused by the logo area may be improved, the degree of deterioration of the red, green, and blue sub-pixels may be similar to each other, and thus, the difference in lifetime between the sub-pixels may be alleviated.

Meanwhile, according to the first exemplary embodiment of the present application, a saturation correction value for the saturation values of all pixels in the edge region is calculated based on one correction coefficient.

On the other hand, according to the second exemplary embodiment of the present application, a correction factor lower than that of the other regions is applied to some of the edge regions having relatively narrow width and thus having relatively low visibility.

7 is a block diagram illustrating the logo area processing unit of FIG. 3 according to the second embodiment of the present application. And, FIG. 8 is a flowchart illustrating a method of driving a display device according to a second exemplary embodiment of the present application. FIG. 9A is a diagram illustrating an example of a peak region among the edge regions of FIG. 6B . FIG. 9B is an enlarged view of pixels on a first line in area A' of FIG. 6A .

7, the logo area processing unit 120' of the display device according to the second exemplary embodiment of the present application further includes a peak area detection unit 126 for detecting a peak area among the edge areas, and a saturation value. The correction unit 123' calculates a chroma correction value for each pixel in the region other than the peak region based on the first correction coefficient, and based on the second correction coefficient lower than the first correction coefficient for each pixel in the peak region This is the same as the first embodiment shown in FIG. 4 except that the saturation correction value is calculated.

And, as shown in FIG. 8 , the method of driving a display device according to the second embodiment further includes a step (S21) of detecting a peak area among the edge areas after the step (S20) of detecting the edge area. It is the same as the first embodiment shown in FIG. 5 except for the point and the point that the saturation correction value is calculated based on the first and second correction coefficients in the step S31 of calculating the saturation correction value. Accordingly, redundant description will be omitted below.

The peak region detection unit 126 detects a portion of the edge region having a relatively low visibility and less than a threshold width as the peak region. (S21)

In addition, the saturation value correcting unit 123 calculates a saturation correction value for the saturation value of each pixel in the region other than the peak region among the edge regions based on the first correction coefficient, and a second correction value lower than the first correction coefficient Based on the coefficient, a saturation correction value for the saturation value of each pixel in the peak region is calculated. (S31) Here, each of the first and second correction coefficients is a rational number between 0 and 1.

Hereinafter, a method of driving a display device according to a second embodiment of the present application will be described using the logo area of FIG. 1 as an example.

As shown in FIG. 9 , among the edge regions expressed in gray scale, region B is darker, clearer, and wider than region C. As shown in FIG. Accordingly, the C region has lower visibility than the B region and has a narrow width, and thus may be detected as a peak region.

That is, the peak region detection unit 126 detects, as a peak region, a partial region less than a predetermined threshold width, ie, region C, among the edge regions by the edge region detection unit 122 . (S21)

The chroma correction unit 123 calculates a chroma correction value for the chroma value of each pixel in the remaining region except for the peak region among the edge regions based on the first correction coefficient, and applies the chroma correction value to the second correction coefficient smaller than the first correction coefficient. Based on the chroma correction value for the chroma value of each pixel in the peak region among the edge regions, a chroma correction value is calculated. (S31)

Specifically, the pixels of the first line of the region A' shown in FIG. 6A will be described as examples.

Table 5 below shows red, green, and blue grayscale values (R, G, B) for each pixel A'P1 to A'P19 of the first line of the region A' shown in FIG. 6A, and Equation 1 The brightness value (INTENSITY) of each pixel (A'P1~A'P19) according to (SATURATION) and saturation correction values (S_C1, S_C2) for the saturation value (SATURATION). For reference, in Table 5, the brightness value (INTENSITY) is indicated to two decimal places, and the saturation value (SATURATION) and the chroma correction values (S_C1, S_C2) are indicated to the third decimal place.

Referring to FIG. 9 , it is assumed that pixels of the edge region detected by the edge region detection unit 122 are A'P3 to A'P8 and A'P14 to A'P17, as indicated by shades in Table 5. Referring to FIG. (S20) Exemplarily, as shown in Table 5, the edge region detection unit 122 may detect a pixel having a difference of more than 6 from the brightness value of at least one of the pixels adjacent to the left and right as the edge region. there is.

And, as indicated by a yellow shade in Table 5, it is assumed that the peak region detected by the peak region detector 126 is pixels A'P14 to A'P17 corresponding to region C of FIG. 9 . (S21)

Next, the chroma correction unit 123 calculates a chroma correction value (S_C1) for the chroma value of each of the pixels A'P3 to A'P8 of the edge region except for the peak region based on the first correction coefficient. and, based on the second correction coefficient, a chroma correction value S_C2 for the chroma values of the pixels A'P14 to A'P17 of the peak region among the edge regions is calculated. (S31)

In this case, each of the first and second correction coefficients is a rational number between 0 and 1, and the second correction coefficient for calculating the saturation correction value of the peak region is smaller than the first correction coefficient. Exemplarily, in the example of Table 4, it is assumed that the first correction coefficient is 0.8 and the second correction coefficient is 0.6.

Next, similarly to the first embodiment, as shown in Table 6 below, the grayscale value correcting unit 124 controls the saturation of each of the pixels A'P3 to A'P8 and A'P14 to A'P17 in the edge region. A gradation correction value MAX_C is calculated based on the correction values S_C1 and S_C2. (S40) That is, as shown in Equation 3 above, the grayscale value correcting unit 124 applies red and green colors to each pixel A'P3 to A'P8 and A'P14 to A'P17 of the edge region. and a grayscale correction value MAX_C corresponding to the minimum value MIN(R,G,B) and the chroma correction values S_C1 and S_C2 among the respective grayscale values R, G, and B of blue color.

Next, the correction signal generating unit 125 generates a correction signal CS based on the gradation correction value MAX_C of each of the pixels A'P3 to A'P8 and A'P14 to A'P17 of the edge region. do. (S50)

As shown in Table 7 below, the correction signal generating unit 125 generates red, green, and blue grayscales for each of the pixels A'P3 to A'P8 and A'P14 to A'P17 in the edge region. At least one of the values R, G, and B that is equal to or greater than the gray level correction value MAX_C is replaced with the gray level correction value MAX_C to generate the correction signal CS. For reference, the gray level correction value (MAX_C) of Table 7 is a value obtained by rounding the gray level correction value (MAX_C) of Table 6 to the first decimal place.

That is, taking pixel A'P3 among the pixels A'P3 to A'P8 and A'P14 to A'P17 of the edge region as an example, red and green for pixel A'P3 according to the image signal IMAGE. and blue grayscale values (R, G, B) are (19, 17, 20), respectively. Since the pixel A'P3 is not a peak region, the grayscale correction value MAX_C of the pixel A'P3 calculated based on the saturation correction value S_C1 according to the first correction coefficient is 19. Accordingly, when the grayscale value B greater than the grayscale correction value MAX_C is replaced with the grayscale correction value MAX_C, each of the red, green, and blue grayscale values R for the pixel A'P3 according to the correction signal CS , G, B) is created as (19, 17, 19 ).

And, taking the A'P14 pixel among the pixels A'P3 to A'P8 and A'P14 to A'P17 of the edge region as another example, the red color for the A'P14 pixel according to the image signal IMAGE, The grayscale values R, G, and B of green and blue respectively are (205, 153, 5). Since the pixel A'P14 is a peak region, the gradation correction value MAX_C of the pixel A'P14 calculated based on the saturation correction value S_C2 according to the second correction coefficient smaller than the first correction coefficient is 12. Accordingly, when the grayscale values R and G greater than the grayscale correction value MAX_C are replaced with the grayscale correction value MAX_C, each of the red, green, and blue grayscale values for the pixel A'P14 according to the correction signal CS (R, G, B) is created as ( 12 , 12 , 5).

As described above, according to the second embodiment of the present application, the saturation correction value is calculated by applying a correction coefficient smaller than that of other regions to the peak region narrow enough not to change the overall shape of the logo among the edge regions of the logo region. do.

Accordingly, the grayscale correction value for each pixel in the peak region is calculated to be smaller by a larger decrease than the grayscale correction value for each pixel in the remaining region except for the peak region among the edge regions. Accordingly, since each pixel in the peak region of the edge region is driven with a lower luminance compared to pixels in the other remaining regions, deterioration can be further prevented. In addition, since the peak area is less than a threshold width that does not affect the shape of the logo, even if each pixel of the peak area is driven with a lower luminance, image processing for the logo area can be prevented from being recognized.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is known in the art to which the present invention pertains that various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the present invention. It will be clear to those who have the knowledge of

100: display device 110: panel unit
P: pixel
R, G, B: Red, Green and Blue sub-pixels
120: logo area processing unit 130: control unit
IMAGE: video signal CS: correction signal
121: logo area detection unit 122: edge area detection unit
123: saturation value correcting unit 124: gradation value correcting unit
125: correction signal generation unit 126: peak area detection unit

Claims (15)

a panel unit including a plurality of pixels defined in a display area displaying an image signal;
An edge region corresponding to an outline of a predetermined mark that is fixedly displayed for a threshold period or longer among the display regions is detected based on the image signal, and a saturation value of each pixel of the edge region is detected based on a preset correction coefficient. a logo area processing unit that calculates a correction value and generates a correction signal for the image signal based on the chroma correction value; and
a control unit for driving the panel unit based on the correction signal;
The logo area processing unit
a logo area detection unit for detecting a logo area corresponding to a predetermined mark that is fixedly displayed over the threshold period based on the image signal;
an edge region detection unit detecting the edge region among the logo regions;
a chroma correction unit calculating the chroma correction value for the chroma value of each pixel of the edge region based on the correction coefficient;
a gradation value corrector configured to calculate a gradation correction value for each pixel of the edge region based on the saturation correction value for each pixel of the edge region; and
and a correction signal generator configured to generate the correction signal based on the gradation correction value for each pixel in the edge region;
The correction factor is a rational number between 0 and 1,
wherein the saturation value correcting unit calculates a product of a saturation value for each pixel in the edge area and the correction coefficient as the saturation correction value for each pixel in the edge area;
The saturation value correcting unit
For each pixel in the edge region, a maximum value and a minimum value among each grayscale value of red, green, and blue are detected, and the remainder obtained by subtracting the ratio of the minimum value to the maximum value from 1 is calculated for each pixel of the edge region. A display device that calculates a saturation value. delete delete delete The method of claim 1,
The gradation value correcting unit
The display device is configured to calculate the gradation correction value based on the saturation correction value and the minimum value. The method of claim 1,
The correction signal generator
The display device generates the correction signal by replacing at least one of red, green, and blue grayscale values equal to or greater than the grayscale correction value with the grayscale correction value for each pixel in the edge region. The method of claim 1,
The logo area processing unit
The display device further comprising a peak area detector for detecting a peak area less than a threshold width of the edge area. 8. The method of claim 7,
The saturation value correcting unit
calculating a chroma correction value for the chroma value of each pixel in a region other than the peak region among the edge regions based on the first correction coefficient;
The display device calculates a chroma correction value for the chroma value of each pixel in the peak region based on a second correction coefficient smaller than the first correction coefficient. A method of driving a display device manufactured according to claim 1, comprising:
detecting the logo area corresponding to a predetermined mark fixedly displayed over a threshold period among the display areas based on the image signal;
detecting the edge area corresponding to the outline of the cover among the logo areas;
calculating a chroma correction value for a chroma value of each pixel in the edge region based on the correction coefficient;
calculating a gradation correction value for each pixel in the edge region based on a saturation correction value for each pixel in the edge region;
generating a correction signal for the image signal based on a gradation correction value for each pixel in the edge region; and
and driving a plurality of pixels based on the correction signal. delete delete 10. The method of claim 9,
In the calculating of the gradation correction value, the gradation correction value is calculated based on the chroma correction value and the minimum value. 10. The method of claim 9,
The step of generating the correction signal is
and generating the correction signal by replacing at least one of red, green, and blue gradation values equal to or greater than the gradation correction value by the gradation correction value for each pixel in the edge region; . 10. The method of claim 9,
After detecting the edge region,
The method of driving a display device further comprising the step of detecting a peak region less than a threshold width among the edge regions. 15. The method of claim 14,
In the step of calculating the saturation correction value,
calculating a chroma correction value for the chroma value of each pixel in a region other than the peak region among the edge regions based on the first correction coefficient;
A method of driving a display device for calculating a chroma correction value for a chroma value of each pixel in the peak region based on a second correction coefficient smaller than the first correction coefficient.

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