Display device and method of driving the same

A display device includes pixels, an image converter which generates a second image by correcting grayscales of a first logo in a first image for the pixels, and a data driver which provides data signals corresponding to the second image to the pixels. The image converter detects the first logo based on value and saturation of the first image, generates first map data corresponding to the first logo, and specifies pixels corresponding to the first logo based on the first map data.

The application claims priority to Korean Patent Application No. 10-2020-0075230, filed Jun. 19, 2020, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.

BACKGROUND

Embodiments of the invention relate to a display device and a method of driving the display device.

2. Description of the Related Art

With the development of information technology, the importance of display devices, which are a connection medium between users and information, has been emphasized. In response to this, the use of display devices such as a liquid crystal display device, an organic light emitting display device, a plasma display device, and the like has been increasing.

A display device may include a plurality of pixels and display an image (frame) through a combination of light emitted from the pixels. When a plurality of different images are continuously displayed, a user may recognize the images as a moving image. In addition, when a plurality of identical images are continuously displayed, the user may recognize the images as a still image.

SUMMARY

In a display device, when a still image is displayed for a long time, or when a part of a moving image such as a logo is displayed for a long time with a same luminance, pixel deterioration and afterimages may occur. In such a display device, grayscales of the logo can be corrected to prevent the afterimages.

Embodiments of the invention are directed to a display device in which a white logo and a color logo displayed in a logo area are accurately extracted and grayscales of the extracted logo are effectively corrected.

An embodiment of a display device according to the invention includes: pixels; an image converter which generates a second image by correcting grayscales of a first logo in a first image for the pixels; and a data driver which provides data signals corresponding to the second image to the pixels. In such an embodiment, the image converter detects the first logo based on value and saturation of the first image, generates first map data corresponding to the first logo, and specifies pixels corresponding to the first logo based on the first map data.

In an embodiment, the image converter may detect a second logo in the first image, generate second map data corresponding to the second logo, specify pixels corresponding to the second logo based on the second map data, and generate the second image by further correcting grayscales of the second logo.

In an embodiment, the image converter may include: a first logo detector which generates first sub-map data based on the value of the first image, generating second sub-map data based on the saturation of the first image, and generates the first map data by combining the first sub-map data and the second sub-map data; a second logo detector which generates the second map data based on a white mark of the first image; a logo determiner which generates third map data using the first map data and the second map data; and a grayscale converter which specifies the pixels corresponding to the first logo and the pixels corresponding to the second logo based on the third map data, and generates the second image by converting grayscales of the pixels corresponding to the first logo and the pixels corresponding to the second logo in the first image.

In an embodiment, the first logo detector may include a coordinate converter which converts the first image of RGB color space coordinates to a third image of HSV color space coordinates.

In an embodiment, the first logo detector may further include: a first map data extractor which generates the first sub-map data corresponding to an area having a value equal to or greater than a threshold value among the third image; and a second map data extractor which generates the second sub-map data corresponding to an area having a saturation equal to or greater than a threshold saturation among the third image.

In an embodiment, the first map data may be generated based on an intersection of the first sub-map data and the second sub-map data.

In an embodiment, the second logo detector may generate the second map data corresponding to an area having a white mark equal to or greater than a threshold white mark in the first image.

In an embodiment, the white mark may be a grayscale value of the first image.

In an embodiment, the second logo detector may generate the second map data based on the value of the first image.

In an embodiment, the third map data may be generated based on a combination of the first map data and the second map data.

In an embodiment, the first logo may include a color mark, and the second logo may include a white mark.

In an embodiment, the first logo detector and the second logo detector may generate the first map data and the second map data based on an Otsu binarization method.

An embodiment of a method of driving a display device according to the invention includes: detecting a first logo in a first image based on value and saturation of the first image; generating first map data corresponding to the first logo; detecting a second logo in the first image based on a white mark of the first image; generating second map data corresponding to the second logo; generating third map data using the first map data and the second map data; specifying pixels corresponding to the first logo and pixels corresponding to the second logo based on the third map data; and generating a second image by correcting grayscales of the pixels corresponding to the first logo and the pixels corresponding to the second logo in the first image.

In an embodiment, the generating the first map data may include: converting the first image of RGB color space coordinates to a third image of HSV color space coordinates; generating first sub-map data corresponding to an area having a value equal to or greater than a threshold value among the third image; generating second sub-map data corresponding to an area having a saturation equal to or greater than a threshold saturation among the third image; and generating the first map data by combining the first sub-map data and the second sub-map data.

In an embodiment, the first map data may be generated based on an intersection of the first sub-map data and the second sub-map data.

In an embodiment, the second map data may be generated corresponding to an area having a white mark equal to or greater than a threshold white mark in the first image.

In an embodiment, the white mark may be a grayscale value of the first image.

In an embodiment, the second map data may be generated based on the white mark and the value of the first image.

In an embodiment, the third map data may be generated based on a combination of the first map data and the second map data.

DETAILED DESCRIPTION

In addition, when an element is “coupled to” or “connected to” another element, this includes not only the case where the element is directly coupled to the other element, but also the case where another element is coupled therebetween. In contrast, when an element is referred to as being “coupled directly to” or “connected directly to” another element, there are no intervening elements present.

Embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.

FIG.1is a block diagram illustrating a display device according to an embodiment of the invention.

Referring toFIG.1, an embodiment of a display device1000according to the invention may include a timing controller100, a data driver200, a scan driver300, a pixel unit400(or a display panel), and an image converter500.

The timing controller100may receive grayscales and control signals for each first image (frame) from an external processor. In one embodiment, for example, in the case of displaying a still image, the grayscales of consecutive first images may be substantially the same as each other. In one embodiment, for example, in the case of displaying a moving image, the grayscales of consecutive first images may be substantially different from each other. In such an embodiment, a part of the moving image may be a still area such as a logo.

The image converter500may generate a second image by correcting the grayscales of the logo in the first image.

In an embodiment, the image converter500may generate (or extract) map data corresponding to a logo area larger than the logo in the first image, and correct the grayscales of the logo using the generated map data.

In one embodiment, for example, the image converter500may generate first map data corresponding to a first logo including a color mark in the first image. In such an embodiment, the image converter500may generate second map data corresponding to a second logo including a white mark in the first image. In such an embodiment, the image converter500may generate third map data using the first map data and the second map data. The image converter500may specify (determine or select) pixels corresponding to the logo (for example, the first logo and/or the second logo) based on the third map data. In such an embodiment, the image converter500may generate the second image by correcting the grayscales of the pixels specified as corresponding to the logo.

The timing controller100may provide the grayscales of the second image to the data driver200. In an embodiment, the timing controller100may provide control signals suitable for each specification to the data driver200, the scan driver300, or the like to display the second image.

In an embodiment, as shown inFIG.1, the timing controller100and the image converter500may be separate components. However, this is merely exemplary, and the timing controller100and the image converter500may be integrally configured as a single unit. In one embodiment, for example, the image converter500may be implemented in a form embedded in the timing controller100.

The data driver200may provide data signals corresponding to the second image to pixels. In one embodiment, for example, the data driver200may generate the data signals to be provided to data lines DL1, DL2, DL3, . . . , and DLn using the grayscales of the second image and the control signals. In one embodiment, for example, the data driver200may sample the grayscales using a clock signal and apply the data signals corresponding to the grayscales to the data lines DL1to DLn in units of pixel rows. A pixel row may mean pixels connected to a same scan line, where n may be an integer greater than 0.

The scan driver300may receive a clock signal, a scan start signal, or the like from the timing controller100and generate scan signals to be provided to scan lines SL1, SL2, SL3, . . . , and SLm, where m may be an integer greater than 0.

The scan driver300may sequentially supply the scan signals having a turn-on level pulse to the scan lines SL1to SLm. In one embodiment, for example, the scan driver300may include scan stages configured in the form of a shift register. The scan driver300may generate the scan signals by sequentially transmitting the scan start signal in the form of a turn-on level pulse to a next scan stage based on the clock signal.

The pixel unit400may include the pixels. Each pixel PXij may be connected to a corresponding data line and a corresponding scan line, where i and j may be integers greater than 0. The pixel PXij may mean a pixel whose scan transistor is connected to an i-th scan line and a j-th data line. In an embodiment, each pixel PXij may receive voltages of a first power source VDD and a second power source VSS from outside. Here, the first power source VDD and the second power source VSS may be voltages used for the operation of the pixels. In one embodiment, for example, the first power source VDD may have a voltage level higher than a voltage level of the second power source VSS.

FIG.2is a circuit diagram illustrating an embodiment of a pixel included in the di splay device ofFIG.1.

Referring toFIG.2, an embodiment of the pixel PXij may include a light emitting element LD and a driving circuit DC connected thereto to drive the light emitting element LD.

A first electrode (for example, an anode electrode) of the light emitting element LD may be connected to the first power source VDD via the driving circuit DC, and a second electrode (for example, a cathode electrode) of the light emitting element LD may be connected to the second power source VSS. The light emitting element LD may emit light at a luminance corresponding to the amount of driving current controlled by the driving circuit DC.

The light emitting element LD may include or be composed of an organic light emitting diode. Alternatively, the light emitting element LD may include or be composed of an inorganic light emitting diode such as a micro light emitting diode (“LED”) or a quantum dot light emitting diode. Alternatively, the light emitting element LD may be an element including or composed of an organic material and an inorganic material. In an embodiment, as shown inFIG.2, the pixel PXij includes a single light emitting element LD. However, in an alternative embodiment, the pixel PXij may include a plurality of light emitting elements, and the plurality of light emitting elements may be connected to each other in series, in parallel or in series and parallel.

The first power source VDD and the second power source VSS may have different potentials from each other. In one embodiment, for example, a voltage applied through the first power source VDD may be greater than a voltage applied through the second power source VSS.

The driving circuit DC may include a first transistor T1, a second transistor T2, and a storage capacitor Cst.

A first electrode of the first transistor T1(a driving transistor) may be connected to the first power source VDD, and a second electrode of the first transistor T1may be electrically connected to the first electrode (for example, the anode electrode) of the light emitting element LD. A gate electrode of the first transistor T1may be connected to a first node N1. The first transistor T1may control the amount of driving current supplied to the light emitting element LD in response to a data signal supplied to the first node N1through a data line DLj.

A first electrode of the second transistor T2(a switching transistor) may be connected to the data line DLj, and a second electrode of the second transistor T2may be connected to the first node N1. A gate electrode of the second transistor T2may be connected to a scan line SLi.

The second transistor T2may be turned on when a scan signal of a voltage (for example, a gate-on voltage) in a turn-on level, at which the second transistor T2is turned on, is supplied from the scan line SLi, and thus the data line DLj and the first node N1may be electrically connected. When the second transistor is turned on, the data signal of a corresponding frame may be supplied to the data line DLj, and accordingly, the data signal may be transmitted to the first node N1. A voltage corresponding to the data signal transmitted to the first node N1may be stored in the storage capacitor Cst.

One electrode of the storage capacitor Cst may be connected to the first node N1, and another electrode of the storage capacitor Cst may be connected to the first electrode of the light emitting element LD. The storage capacitor Cst may be charged with the voltage corresponding to the data signal supplied to the first node N1, and may maintain the charged voltage until the data signal of the next frame is supplied.

FIG.2shows an embodiment of the pixel PXij having a relatively simple structure for convenience of illustration and description. However, the structure of the driving circuit DC may be variously changed or modified. In one alternative embodiment, for example, the driving circuit DC may include various transistors such as a compensation transistor for compensating a threshold voltage of the first transistor T1, an initialization transistor for initializing the first node N1, and/or a light emitting control transistor for controlling a light emitting time of the light emitting element LD. In an alternative embodiment, the driving circuit DC may further include other circuit elements such as a boosting capacitor for boosting the voltage of the first node N1.

In an embodiment, as shown inFIG.2, the transistors included in the driving circuit DC, for example, the first and second transistors T1and T2may be N-type transistors, but the invention is not limited thereto. Alternatively, at least one of the first and second transistors T1and T2included in the driving circuit DC may be a P-type transistor.

FIG.3is a diagram showing embodiments of a first image, a logo area, a first logo, and a second logo.

Referring toFIGS.1and3,FIG.3shows an embodiment where the pixel unit400displays a first image IMG1, for example. The first image IMG1may be data including the grayscales for each of the pixels of the pixel unit400. Here, one first image IMG1may correspond to one frame. Herein, a period in which one first image IMG1is displayed may be referred to as one frame period. In such an embodiment, a start time point and an end time point of the frame period may be different for each pixel row. In one embodiment, for example, a time point when scan transistors of a pixel row are turned on to receive the data signals corresponding to the current first image IMG1may be the start time point of the frame period of the pixel row, and a time point when the scan transistors are turned on again to receive the data signals corresponding to the next first image IMG1may be the end time point of the frame period of a corresponding pixel row.

The logo area (or an area including the first logo LG1and/or the second logo LG2) may be a still image area in which the position and grayscale are maintained in consecutive first images IMG1. In one embodiment, for example, the first logo LG1may be a logo including the color mark, and the second logo LG2may be a logo including the white mark. In such an embodiment, the first logo LG1may be displayed in a form surrounding a part of the second logo LG2(e.g., the letter “S” shown inFIG.3).

A logo area LGA may include the first and second logos LG1and LG2and may be an area larger than the first and second logos LG1and LG2. In one embodiment, for example, the logo area LGA may be a rectangular area, such that the logo area LGA may be easily defined with coordinate values based on the x and y axes. In an alternative embodiment, the logo area LGA may be defined as other shapes such as a circle or an oval. An area other than the first and second logos LG1and LG2among the logo area LGA may be defined as a background.

FIG.4is a block diagram illustrating an embodiment of an image converter included in the display device ofFIG.1.FIG.5is a block diagram illustrating an embodiment of a first logo detector included in the image converter ofFIG.4.FIGS.6A and6Bare diagrams showing an embodiment of first sub-map data generated by a first map data extractor included in the first logo detector ofFIG.5.FIGS.7A and7Bare diagrams showing an embodiment of second sub-map data generated by a second map data extractor included in the first logo detector ofFIG.5.FIG.8is a diagram showing an embodiment of first map data generated by a map data generator included in the first logo detector ofFIG.5.FIGS.9A and9Bare diagrams showing an embodiment of second map data generated by a second logo detector included in the image converter ofFIG.4.FIG.10is a diagram showing an embodiment of third map data generated by a logo determiner included in the image converter ofFIG.4.

Referring toFIGS.3and4, an embodiment of the image converter500according to the invention may include a first logo detector510, a second logo detector520, a logo determiner530, and a grayscale converter540.

In an embodiment, the image converter500may generate (or extract) map data (first to third map data LMR1, LMR2, and LMF) corresponding to the logo area LGA in the first image IMG1, and correct the grayscales of the first logo LG1and/or the second logo LG2using the generated map data LMR1, LMR2, and LMF.

In one embodiment, for example, the image converter500may generate the first map data LMR1corresponding to the first logo LG1including the color mark in the first image IMG1. In such an embodiment, the image converter500may generate the second map data LMR2corresponding to the second logo LG2including the white mark in the first image IMG1. In such an embodiment, the image converter500may generate the third map data LMF using the first map data LMR1and the second map data LMR2. The image converter500may specify the pixels corresponding to the first logo LG1and/or the second logo LG2based on the third map data LMF. In an embodiment, the image converter500may generate second image IMG2by correcting the grayscales of the pixels specified as corresponding to the first logo LG1and/or the second logo LG2.

The first logo detector510may detect the first logo LG1in the first image IMG1and generate the first map data LMR1corresponding to the first logo LG1.

In an embodiment, the first logo detector510may convert the first image IMG1from RGB color space coordinates to HSV color space coordinates to detect the first logo LG1including the color mark, and detect the first logo LG1based on value (or brightness) and saturation in the logo area LGA among the converted first image IMG1(hereinafter, referred to as a third image).

Referring toFIG.5, an embodiment of the first logo detector510may include a coordinate converter511, a first map data extractor512, a second map data extractor513, and a map data generator514.

The coordinate converter511may convert the first image IMG1of the RGB color space coordinates to a third image IMG1_1of the HSV color space coordinates. In an embodiment, each pixel (for example, the pixel Pxij shown inFIG.2) of the display device (for example, the display device1000shown inFIG.1) may include a sub-pixel that emits red light, a sub-pixel that emits green light, and a sub-pixel that emits blue light. In such an embodiment, the first image IMG1may be expressed in the RGB color space coordinates of red, green, and blue. In such an embodiment, the coordinate converter511may generate the third image IMG1_1of the HSV color space coordinates having hue, saturation, and value (or brightness) by converting the first image IMG1of the RGB color space coordinates to detect the first logo LG1of the color mark.

The first map data extractor512may generate (or extract) first sub-map data LMD1based on the third image IMG1_1of the HSV color space coordinates.

In an embodiment, the first map data extractor512may generate the first sub-map data LMD1based on an area having the value equal to or greater than a predetermined threshold value in the logo area LGA.

In one embodiment, for example, as shown inFIGS.6A and6B, the first map data extractor512may generate the first sub-map data LMD1shown inFIG.6Bby extracting pixels having the value of 714 or more, which is a threshold value Vth (or a threshold brightness), among the logo area LGA. Here, the threshold value Vth may be a predetermined value by an experiment or the like. The value of 714 is merely an example, and the threshold value Vth is not limited thereto.

In an embodiment, the first logo LG1including the color mark as well as the second logo LG2including the white mark may have a high value. In such an embodiment, when a relatively bright image is displayed in the area (or background) excluding the first and second logos LG1and LG2among the logo area LGA according to the image displayed by the first image IMG1, the value in the corresponding area may be high. In this case, on the first sub-map data LMD1, the pixels corresponding to the first logo LG1as well as the pixels corresponding to the second logo LG2and/or the area in which the bright image is displayed (or a noise area NS) may be extracted as pixels having the threshold value Vth or higher.

The second map data extractor513may generate (or extract) second sub-map data LMD2based on the third image IMG1_1of the HSV color space coordinates.

In an embodiment, the second map data extractor513may generate the second sub-map data LMD2based on an area having the saturation equal to or greater than a predetermined threshold saturation in the logo area LGA.

In one embodiment, for example, as shown inFIGS.7A and7B, the second map data extractor513may generate the second sub-map data LMD2shown inFIG.7Bby extracting pixels having the value of 0.5 or more, which is a threshold saturation Sth, among the logo area LGA. Here, the threshold saturation Sth may be a predetermined value by an experiment or the like. The value of 0.5 is merely an example, and the threshold saturation Sth is not limited thereto.

In an embodiment, in the image displayed by the first image IMG1as well as the first logo LG1including the color mark, a high saturation image may be displayed in the area excluding the first and second logos LG1and LG2(or the background) among the logo area LGA. In this case, on the second sub-map data LMD2, the pixels corresponding to the first logo LG1as well as the pixels corresponding to the area in which the high saturation image is displayed (or a noise area NS) may be extracted as pixels having the threshold saturation Sth or higher.

The map data generator514may generate the first map data LMR1corresponding to the first logo LG1by detecting the first logo LG1including the color mark.

In an embodiment, the map data generator514may generate the first map data LMR1using the first sub-map data LMD1and the second sub-map data LMD2. In one embodiment, for example, since the first logo LG1displayed in the logo area LG includes the color mark, the value and saturation of the first logo LG1may be relatively high. The map data generator514may generate the first map data LMR1ofFIG.8by combining the first sub-map data LMD1and the second sub-map data LMD2. In one embodiment, for example, as shown inFIG.8, the first map data LMR1may be generated based on or in the form of an intersection of the first sub-map data LMD1and the second sub-map data LMD2. Accordingly, on the first map data LMR1, the pixels corresponding to the first logo LG1that is greater than or equal to the threshold value Vth and greater than or equal to the threshold saturation Sth may be extracted. In such an embodiment, since the first sub-map data LMD1and the second sub-map data LMD2are combined in the form of the intersection to generate the first map data LMR1, only pixels corresponding to the first logo LG1except for the noise area (for example, the noise area NS shown inFIG.6Aand/orFIG.7A) may be accurately extracted on the first map data LMR1.

Referring back toFIG.4, the second logo detector520may generate the second map data LMR2corresponding to the second logo LG2by detecting the second logo LG2in the first image IMG1.

In an embodiment, the second logo detector520may generate the second map data LMR2based on an area having the white mark equal to or greater than a predetermined threshold white mark to detect the second logo LG2including the white mark.

In one embodiment, for example, as shown inFIGS.9A and9B, the second logo detector520may generate the second map data LMR2shown inFIG.9Bby extracting the pixels having the white mark of 714 or more, which is a threshold white mark Wth among the logo area LGA. Here, the threshold white mark Wth may be a predetermined value by an experiment or the like. The value of 714 is merely an example, and the threshold white mark Wth is not limited thereto.

In an embodiment, the white mark may be a grayscale value of the first image IMG1.

In an embodiment, the second logo detector520may generate the second map data LMR2using the value as well as the white mark. In one embodiment, for example, the second logo detector520may generate the second map data LMR2by extracting pixels having the white mark of 714 or more, which is the threshold white mark Wth, and the value of 714 or more, which is the threshold value Vth among the logo area LGA. Since the second logo LG2including the white mark is displayed as a relatively bright image, when the second logo detector520generates the second map data LMR2using the value as well as the white mark, accuracy may be further improved in extracting the second logo LG2.

In an embodiment, the first and second logo detectors510and520may use a conventional logo detection algorithm to extract the first and second logos LG1and LG2. In one embodiment, for example, a logo detection algorithm using Otsu binarization method may be performed. Otsu binarization method is an adaptive thresholding way for binarization in image processing, which is well known in the art.

The logo determiner530may generate the third map data LMF using the first map data LMR1and the second map data LMR2. In one embodiment, for example, the logo determiner530may generate the third map data LMF by extracting pixels extracted corresponding to the first logo LG1on the first map data LMR1and pixels extracted corresponding to the second logo LG2on the second map data LMR2as the pixels corresponding to the logo. In one embodiment, for example, the third map data LMF may be generated in the form of a union (or based on a combination) of the first map data LMR1and the second map data LMR2as shown inFIG.10. In such an embodiment, since the first map data LMR1and the second map data LMR2are combined in the form of the union to generate the third map data LMF, all pixels corresponding to the first logo LG1and the second logo LG2may be extracted on the third map data LMF.2

The grayscale converter540may specify the pixels corresponding to the first and second logos LG1and LG2based on the third map data LMF, and generate the second image IMG2by converting the grayscales of the specified pixels in the first image IMG1.

The grayscale converter540may generate the second image IMG2by reducing the grayscales of the pixels corresponding to the first and second logos LG1and LG2in the first image IMG1. Accordingly, luminance of light emitted from the pixels corresponding to the first and second logos LG1and LG2among consecutive frame periods may be reduced to prevent afterimages.

In embodiments of the invention, as described above with reference toFIGS.4and5, the image converter500may accurately extract the first logo LG1and the second logo LG2of the logo area LGA, and correct the grayscales of the pixels corresponding to the first logo LG1including the color mark as well as the second logo LG2including the white mark among the logo area LGA. Accordingly, pixel deterioration and afterimages in the logo area LGA may be removed (or reduced).

Embodiments of the display device according to the invention may accurately extract a color logo as well as a white logo displayed in the logo area and correct the grayscales of the extracted logo. Accordingly, the pixel deterioration and afterimages in the logo area LGA may be removed (or reduced).