Display device and driving method thereof

Abstract

The present invention relates to a display device and a driving method thereof. The display device includes a pixel, an image converter that generates a second image by correcting a gray scale of a logo in a first image for the pixel, and a data driver that provides a data voltage corresponding to the second image to the pixel. The image converter generates first accumulated data by accumulating first map data corresponding to a logo area larger than the logo in the first image during a plurality of frame periods, generates second accumulated data by scaling the first accumulated data per refresh period, generates third accumulated data by initializing values less than a first threshold value in the second accumulated data to a background value, and specifies the pixel corresponding to the logo based on second map data corresponding to the third accumulated data.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and all benefits arising from Korean Patent Application No. 10-2020-0064181, filed on May 28, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Embodiments of the present invention relate to a display device and a driving method thereof. Background Art

[0004] With the development of information technology, display devices that serve as a connection medium between users and information have been widely used. Such display devices may include liquid crystal display devices, organic light emitting display devices, plasma display devices, and the like.

[0005] The display device may include a plurality of pixels and display an image (frame) by combining the light emitted from the pixels. When a plurality of different images are displayed continuously, the user may recognize the image as a moving image. In addition, when a plurality of identical images are displayed continuously, the user may recognize the image as a still image. Summary of the Invention

[0006] In display devices, pixel degradation and image retention can occur when a still image is displayed for a long time, or when a portion of a moving image, such as a logo, is displayed at the same brightness for a long time. Therefore, in display devices, the grayscale of the logo can be corrected to prevent image retention. However, it can be difficult to accurately identify the pixels corresponding to the logo.

[0007] The embodiment relates to a display device and a driving method thereof for effectively preventing an afterimage by accurately specifying pixels corresponding to a logo.

[0008] An embodiment of a display device according to the present invention includes: a pixel; an image converter that generates a second image by correcting the grayscale of a marker in a first image for the pixel; and a data driver that provides a data voltage corresponding to the second image to the pixel. In such an embodiment, the image converter generates first accumulated data by accumulating first map data corresponding to a marker area larger than the marker in the first image over multiple frame periods, generates second accumulated data by scaling the first accumulated data at each refresh cycle, generates third accumulated data by initializing a value less than a first threshold in the second accumulated data as a background value, and designates a pixel corresponding to the marker based on the second map data corresponding to the third accumulated data.

[0009] In an embodiment, the image converter may include a landmark detector that detects a landmark area in the first image, and the landmark detector may generate first map data in which pixels in the landmark area identified as a landmark are indicated as a first binary level and pixels in the landmark area identified as a background are indicated as a second binary level.

[0010] In an embodiment, the image converter may further include a memory and a data accumulator generating the first accumulated data, and the data accumulator may generate the first accumulated data by accumulating the first map data in the memory data received from the memory.

[0011] In an embodiment, the data accumulator may generate the first accumulated data by adding the first map data to the memory data.

[0012] In an embodiment, the data accumulator may generate first compensated map data by applying an increase to a first binary level of the first map data and a decrease to a second binary level, and generate first accumulated data by adding the first compensated map data to the memory data.

[0013] In an embodiment, the increase amount may be greater than the decrease amount.

[0014] In an embodiment, the image converter may further include a scaler that generates the second accumulated data by downscaling the first accumulated data at each refresh period, and the refresh period may correspond to p frame periods, and p may be an integer greater than 1.

[0015] In an embodiment, a resolution of unit data corresponding to each pixel in the memory data in the memory may be smaller than p.

[0016] In an embodiment, the image converter may further include a cropping unit that generates the third accumulated data by initializing a value smaller than the first threshold value in the second accumulated data as a background value, and the background value may be the same as the second binary level.

[0017] In an embodiment, the memory may store the third accumulated data as memory data.

[0018] In an embodiment, the image converter may further include a flag determination unit that generates the second map data, and the flag determination unit may generate the second map data by replacing values ​​greater than a second threshold value in the third accumulated data with a first binary level and by replacing values ​​less than the second threshold value in the third accumulated data with a second binary level.

[0019] In an embodiment, the image converter may further include a grayscale converter that generates a second image by designating pixels corresponding to the mark based on the second map data and converting the grayscale of the designated pixels in the first image, and the grayscale converter may designate pixels corresponding to the first binary level in the second map data as pixels corresponding to the mark.

[0020] In an embodiment, the grayscale converter may generate the second image by reducing the grayscale of pixels corresponding to the logo in the first image.

[0021] An embodiment of a driving method for a display device according to the present invention includes: generating first accumulated data by accumulating first map data corresponding to a mark area larger than the mark in a first image during multiple frame periods; generating second accumulated data by scaling the first accumulated data in each refresh cycle; generating third accumulated data by initializing a value less than a first threshold in the second accumulated data as a background value; specifying pixels corresponding to the mark based on second map data corresponding to the third accumulated data; and generating a second image by correcting the grayscale of the specified pixels corresponding to the mark in the first image.

[0022] In an embodiment, the driving method may further include generating first map data in which pixels in the logo area identified as a logo are indicated as a first binary level, and pixels in the logo area identified as a background are indicated as a second binary level.

[0023] In an embodiment, generating the first accumulated data may include generating the first compensated map data by applying an increase to a first binary level of the first map data and a decrease to a second binary level, and generating the first accumulated data by adding the first compensated map data to the memory data, wherein the increase may be greater than the decrease.

[0024] In an embodiment, the refresh cycle may correspond to p frame periods, where p may be an integer greater than 1. In such an embodiment, a resolution of unit data corresponding to each pixel in the memory data may be less than p.

[0025] In an embodiment, the background value may be the same as the second binary level, and the driving method may further include storing the third accumulated data as memory data.

[0026] In an embodiment, the driving method may further include generating second map data by replacing values ​​greater than a second threshold value in the third accumulated data with a first binary level and replacing values ​​less than the second threshold value in the third accumulated data with a second binary level.

[0027] In an embodiment, generating the second image may include reducing the grayscale of pixels in the first image designated to correspond to the marker. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other features of the present invention will become more apparent by further describing embodiments of the present invention with reference to the accompanying drawings, in which:

[0029] Figure 1 is a block diagram showing a display device according to an embodiment of the present invention;

[0030] Figure 2 is a circuit diagram showing a pixel according to an embodiment of the present invention;

[0031] Figure 3 is a diagram showing a first image, a logo, and a logo area;

[0032] Figure 4 is a block diagram showing an image converter according to an embodiment of the present invention;

[0033] Figure 5 is a diagram showing first map data according to an embodiment of the present invention;

[0034] Figure 6 is a diagram showing memory data according to an embodiment of the present invention;

[0035] Figure 7 is a diagram showing first accumulated data according to an embodiment of the present invention;

[0036] Figure 8 is a block diagram showing a noise removal unit according to an embodiment of the present invention;

[0037] Figure 9 is a diagram showing first accumulated data according to an embodiment of the present invention;

[0038] Figure 10 is a diagram showing second accumulated data according to an embodiment of the present invention;

[0039] Figure 11 is a diagram showing third accumulated data according to an embodiment of the present invention;

[0040] Figure 12 is a diagram showing second map data according to an embodiment of the present invention;

[0041] Figure 13 is a diagram showing first compensation map data according to an embodiment of the present invention; and

[0042] Figure 14 is a diagram showing first compensation map data according to an alternative embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention will now be described more fully with reference to the accompanying drawings showing various embodiments. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Throughout the text, the same reference numerals refer to the same elements.

[0044] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, the "first element," "first component," "first region," "first layer," or "first section" discussed below may be referred to as a second element, second component, second region, second layer, or second section without departing from the teachings herein.

[0045] The terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, "one", "the" and "at least one" do not represent quantitative limitations and are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "an element" has the same meaning as "at least one element" unless the context clearly indicates otherwise. "At least one" should not be interpreted as a restrictive "one". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. It will be further understood that when used in this specification, the terms "include" and / or "comprising" specify the presence of the features, regions, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, parts and / or their groups.

[0046] Furthermore, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the accompanying drawings. For example, if the device in one of the accompanying drawings is turned over, an element described as being on the "lower" side of the other elements would subsequently be oriented on the "upper" side of the other elements. Thus, the term "lower" may encompass both orientations of "lower" and "upper" depending on the particular orientation of the drawing. Similarly, if the device in one of the accompanying drawings is turned over, an element described as being "below" or "beneath" the other elements would subsequently be oriented "above" the other elements. Thus, the term "lower" or "beneath" may encompass both orientations of "upper" and "lower," depending on the particular orientation of the drawing.

[0047] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant art and the context of this disclosure, and, unless expressly defined as such herein, will not be interpreted in an idealized or overly formal sense.

[0048] The embodiments described herein should not be construed as limited to the specific shapes of regions as illustrated herein, but rather should include shape deviations resulting from, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. Furthermore, illustrated sharp corners may be rounded. Accordingly, the regions illustrated in the drawings are schematic in nature, and their shapes are not intended to illustrate the precise shapes of the regions or to limit the scope of the claims.

[0049] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0050] Figure 1 is a block diagram showing a display device according to an embodiment of the present invention.

[0051] Reference Figure 1 , an embodiment of a display device 10 according to the present invention may include a timing controller 11 , a data driver 12 , a scan driver 13 , a pixel unit 14 , and an image converter 15 .

[0052] The timing controller 11 may receive the grayscale and control signal for each first image (frame) from an external processor. In one embodiment, for example, when displaying a still image, the grayscales of consecutive first images may be substantially the same. In another embodiment, for example, when displaying a moving image, the grayscales of consecutive first images may be substantially different. In such an embodiment, a portion of the moving image may be a still area image such as a logo.

[0053] The image converter 15 can generate the second image by correcting the grayscale of the mark in the first image. In one embodiment, for example, the image converter 15 can generate first accumulated data by accumulating first map data corresponding to a mark area larger than the mark in the first image over multiple frame periods. The image converter 15 can generate second accumulated data by scaling the first accumulated data during each refresh cycle. The image converter 15 can generate third accumulated data by initializing values ​​in the second accumulated data that are less than a first threshold value to a background value. The image converter 15 can specify pixels corresponding to the mark based on the second map data corresponding to the third accumulated data. In such an embodiment, the image converter 15 can generate the second image by correcting the grayscale of the specified pixels corresponding to the mark.

[0054] In an embodiment, the timing controller 11 may provide the grayscale of the second image to the data driver 12. In such an embodiment, the timing controller 11 may provide a control signal suitable for each specification to the data driver 12 or the scan driver 13 for displaying the second image.

[0055] The data driver 12 can provide data voltages corresponding to the second image to the pixels. In one embodiment, for example, the data driver 12 can generate data voltages to be provided to the data lines DL1, DL2, DL3, ..., and DLn based on the grayscale of the second image and a control signal. In one embodiment, for example, the data driver 12 can sample the grayscale using a clock signal and apply data voltages corresponding to the grayscale to the data lines DL1 to DLn on a pixel row basis. A pixel row can refer to pixels connected to the same scan line, where n can be an integer greater than 0.

[0056] The scan driver 13 may receive a clock signal or a scan start signal, etc. from the timing controller 11 and generate scan signals to be provided to the scan lines SL1 , SL2 , SL3 , . . . , and SLm, where m may be an integer greater than 0.

[0057] The scan driver 13 may sequentially supply scan signals having on-level pulses to the scan lines SL1 to SLm. The scan driver 13 may include a scan stage in the form of a shift register. The scan driver 13 may generate the scan signals by sequentially transmitting a scan start signal in the form of an on-level pulse to the next scan stage under the control of a clock signal.

[0058] The pixel unit 14 may include pixels. Each pixel PXij may be connected to a corresponding data line and a scan line, where i and j may be integers greater than 0. The pixel PXij may refer to a pixel whose scan transistor is connected to the i-th scan line and the j-th data line.

[0059] Figure 2 is a circuit diagram showing a pixel according to an embodiment of the present invention.

[0060] Reference Figure 2 , an embodiment of the pixel PXij may include a first transistor T1 and a second transistor T2 , a storage capacitor Cst, and a light emitting diode LD.

[0061] Hereinafter, for the convenience of explanation, an embodiment in which the circuit of pixel PXij includes an N-type transistor will be described in detail, but is not limited thereto. Alternatively, the circuit of pixel PXij can include a P-type transistor by changing the polarity of the voltage applied to the gate terminal. Alternatively, the circuit of pixel PXij can include a combination of a P-type transistor and an N-type transistor. A P-type transistor generally refers to a transistor whose amount of current conducted increases when the voltage difference between the gate electrode and the source electrode increases in the negative direction. An N-type transistor generally refers to a transistor whose amount of current conducted increases when the voltage difference between the gate electrode and the source electrode increases in the positive direction. Each of the transistors can be configured in various forms such as a thin film transistor ("TFT"), a field effect transistor ("FET"), or a bipolar junction transistor ("BJT").

[0062] The first transistor T1 may include a gate electrode connected to the first electrode of the storage capacitor Cst, a first electrode connected to the first power line ELVDDL, and a second electrode connected to the second electrode of the storage capacitor Cst. The first transistor T1 may be referred to as a driving transistor.

[0063] The second transistor T2 may include a gate electrode connected to the i-th scan line SLi, a first electrode connected to the j-th data line DLj, and a second electrode connected to the gate electrode of the first transistor T1. The second transistor T2 may be referred to as a scan transistor.

[0064] A first electrode of the storage capacitor Cst may be connected to the gate electrode of the first transistor T1 , and a second electrode may be connected to the second electrode of the first transistor T1 .

[0065] The light emitting diode LD may include an anode connected to the second electrode of the first transistor T1 and a cathode connected to the second power line ELVSSL. The light emitting diode LD may include an organic light emitting diode, an inorganic light emitting diode, or a quantum dot / well light emitting diode, etc., or may be composed of an organic light emitting diode, an inorganic light emitting diode, or a quantum dot / well light emitting diode, etc. In an embodiment, as Figure 2 As shown in FIG, the pixel PXij may include a single light emitting diode LD, but is not limited thereto. In an alternative embodiment, the pixel PXij may include a plurality of light emitting diodes connected in series, in parallel, or in series and parallel.

[0066] A first power supply voltage can be applied to the first power supply line ELVDDL, and a second power supply voltage can be applied to the second power supply line ELVSSL. In one embodiment, for example, the first power supply voltage can be greater than the second power supply voltage.

[0067] In an embodiment, when a scan signal of an on level (here, a logic high level) is applied through the scan line SLi, the second transistor T2 can turn on. When the second transistor T2 turns on, a data voltage applied to the data line DLj can be stored in the first electrode of the storage capacitor Cst.

[0068] A positive drive current corresponding to a voltage difference between the first electrode and the second electrode of the storage capacitor Cst can flow between the first electrode and the second electrode of the first transistor T1. Accordingly, the light emitting diode LD can emit light having a luminance corresponding to the data voltage.

[0069] In such an embodiment, when a scan signal of an off level (here, a logic low level) is applied through the scan line SLi, the second transistor T2 can turn off, and the data line DLj can be electrically isolated from the first electrode of the storage capacitor Cst. Accordingly, even if a data voltage of the data line DLj changes, a voltage stored in the first electrode of the storage capacitor Cst can not change.

[0070] The above-described features can not only be applicable to the pixel PXij including the pixel circuit 10, but also to pixels including other pixel circuits. Figure 2

[0071] Figure 3 is a diagram illustrating a first image, a logo, and a logo area.

[0072] Referring to Figure 3 , an embodiment in which a first image IMG1 displayed on the pixel unit 14 is illustrated. The first image IMG1 can be data including a gray scale of each of the pixels of the pixel unit 14. One first image IMG1 can correspond to one frame image. A period in which one first image IMG1 is displayed can be one frame period. In such an embodiment, a start time point and an end time point of the frame period can be different for each pixel row. In one embodiment, for example, a time point at which a scan transistor of a pixel row turns on to receive a data voltage corresponding to a current first image IMG1 can be a start time point of a frame period of the corresponding pixel row. A time point at which the scan transistor of the pixel row turns on again to receive a data voltage corresponding to a next first image IMG1 can be an end time point of the frame period of the corresponding pixel row.

[0073] ​The logo LG may be a still image in which the position and grayscale of the continuous first image IMG1 are maintained. The logo area LGA may include the logo LG and may be an area larger than the logo LG. In one embodiment, for example, the logo area LGA may be a rectangular area. In such an embodiment, the logo area LGA is a rectangular area so that the logo area LGA can be effectively defined using coordinate values ​​based on the x-axis and the y-axis. In an alternative embodiment, the logo area LGA may be defined as another shape such as a circle or an ellipse. The area other than the logo LG in the logo area LGA may be defined as a background.

[0074] Figure 4 is a block diagram illustrating an image converter according to an embodiment of the present invention. Figure 5 is a diagram showing first map data according to an embodiment of the present invention. Figure 6 is a diagram showing memory data according to an embodiment of the present invention.

[0075] Figure 7 is a diagram showing first accumulated data according to an embodiment of the present invention. Figure 8 is a block diagram illustrating a noise removing unit according to an embodiment of the present invention. Figure 9 is a diagram showing first accumulated data according to an embodiment of the present invention.

[0076] Figure 10 is a diagram showing second accumulated data according to an embodiment of the present invention. Figure 11 is a diagram showing third accumulated data according to an embodiment of the present invention. Figure 12 is a diagram showing second map data according to an embodiment of the present invention.

[0077] Reference Figure 4 , an embodiment of the image converter 15 according to the present invention may include a sign detector 151, a data accumulator 152, a memory 153, a noise removal unit 154, a sign determination unit 155, and a grayscale converter 156. In such an embodiment, the image converter 15 may be in the form of a circuit.

[0078] The image converter 15 may generate the first accumulated data ACR by accumulating the first map data LMR corresponding to the mark area LGA larger than the mark LG in the first image IMG1 during a plurality of frame periods. The image converter 15 may generate the second accumulated data SACR by scaling the first accumulated data ACR at each refresh period (in Figure 8). The image converter 15 may generate third accumulated data ACF by initializing a value less than the first threshold value in the second accumulated data SACR as a background value. The image converter 15 may specify pixels corresponding to the marker LG based on the second map data LMF corresponding to the third accumulated data ACF. In such an embodiment, the image converter 15 may generate a second image IMG2 by correcting the grayscale of the specified pixels corresponding to the marker LG.

[0079] The landmark detector 151 may detect the landmark area LGA in the first image IMG1. A method for detecting the landmark area LGA may be performed using a conventional landmark detection algorithm. In one embodiment, for example, a landmark detection algorithm using Otsu binarization may be performed.

[0080] The sign detector 151 may generate first map data LMR in which pixels identified as the sign LG in the sign area LGA are indicated as a first binary level, and pixels identified as the background in the sign area LGA are indicated as a second binary level. In an embodiment, the first binary level may be set to 1 and the second binary level may be set to 0 in the first map data LMR, as shown in FIG. Figure 5 In one embodiment, for example, in the first map data LMR, the values ​​of the pixels PX1 and PX3 corresponding to the logo LG may be 1, and the values ​​of the pixels corresponding to the background may be 0. However, in such an embodiment, the first map data LMR may include the following: Figure 5 The error for pixel PX2 is shown in FIG, where the value of pixel PX2 corresponding to the background in the first map data LMR is 1 due to an error or limitation in the landmark detection algorithm.

[0081] The data accumulator 152 may generate first accumulated data ACR. The data accumulator 152 may generate the first accumulated data ACR by accumulating the first map data LMR in the memory data MRD received from the memory 153. In one embodiment, for example, the data accumulator 152 may generate the first accumulated data ACR by adding the first map data LMR to the memory data MRD.

[0082] Reference Figure 6, an embodiment of the memory data MRD is shown. In one embodiment, for example, the memory 153 can express unit data corresponding to each pixel in 8 bits (0 to 63). In one embodiment, for example, in the memory data MRD, the value of the pixel PXl can be 63, the value of the pixel PX2 can be 3, and the value of the pixel PX3 can be 62. That is, the values of the pixels PXl and PX3 corresponding to the logo LG in the memory data MRD can generally be high, and the value of the pixel PX2 corresponding to the background can be substantially low or 0.

[0083] Referring to Figure 7 , an embodiment of the first accumulated data ACR obtained by adding the first map data LMR to the memory data MRD is shown. Since the value of the pixel PXl is already the maximum value of 63, even if the value of 1 of the first map data LMR is added, the value cannot be increased and can be maintained at 63. That is, the value of the pixel PXl can be in a saturated state, and cannot be accumulated or further increased. Since the value of the unsaturated pixel PX2 is 3, the value can be increased. Since the value of the unsaturated pixel PX3 is 62, the value can be increased. In this case, because the first map data LMR is accumulated in the memory 153 for a long time, the possibility that the pixel PX2 corresponding to the background is erroneously determined as a pixel corresponding to the logo LG can increase. In an embodiment, the image converter 15 of the present application can include the noise removal unit 154 to effectively prevent the pixel PX2 corresponding to the background from being erroneously determined as a pixel corresponding to the logo LG.

[0084] Referring to Figure 8 , an embodiment of the noise removal unit 154 can include a sealer 1541 and a clipping unit 1542.

[0085] The sealer 1541 can generate the second accumulated data SACR by reducing the first accumulated data ACR at each refresh period. In one embodiment, for example, the second accumulated data SACR can be generated by reducing the first accumulated data ACR shown in Figure 9 to 75% so that the data corresponding to the logo LG and the data corresponding to the background (or Figure 9 shown in FIG. 4 can be reduced. Figure 10

[0086] The clipping unit 1542 can generate the third accumulated data ACF by initializing the values less than the first threshold value in the second accumulated data SACR to a background value. In one embodiment, for example, the background value can be the same as the second binary level (here, 0). Referring to Figure 11 ​The third accumulated data ACF may include only values ​​corresponding to the flag LG greater than the first threshold and may not include values ​​corresponding to the noise NS less than the first threshold. The first threshold may be determined experimentally or by a conventional algorithm in advance.

[0087] The memory 153 may store the third accumulated data ACF as memory data MRD. In such an embodiment, the memory data MRD may be updated with the third accumulated data ACF. Therefore, the first map data LMR corresponding to the first image IMG1 of the next frame period may be accumulated again in the updated memory data MRD.

[0088] According to the embodiment, not only is the noise NS removed from the memory data MRD, but also the value of the pixel PX1 corresponding to the flag LG can be released from the saturation state. Therefore, the first map data LMR can be continuously accumulated in the memory data MRD.

[0089] According to an embodiment, the refresh cycle may correspond to p frame periods. In such an embodiment, the memory 153 may be configured so that the resolution of the unit data corresponding to each pixel in the memory data MRD is less than p. Here, p may be an integer greater than 1. In one embodiment, for example, Figures 5 to 7 As shown in , p may be 64. According to experiments, when the refresh cycle corresponds to twice the resolution of the unit data of the memory data MRD (eg, 128 frame periods), the mark LG not including the noise NS may be smoothly detected.

[0090] The noise removal unit 154 may operate only in the frame period corresponding to the refresh cycle and may not operate in the frame period other than the refresh cycle. In one embodiment, for example, the noise removal unit 154 may provide the third accumulated data ACF to the flag determination unit 155 and the memory 153 in the frame period corresponding to the refresh cycle. In such an embodiment, the noise removal unit 154 may provide the first accumulated data ACR to the flag determination unit 155 and the memory 153 in the frame period other than the refresh cycle.

[0091] The flag determination unit 155 may generate the second map data LMF. The flag determination unit 155 may generate the second map data LMF by replacing values ​​greater than a second threshold value in the third accumulated data ACF with a first binary level and replacing values ​​less than the second threshold value in the third accumulated data ACF with a second binary level. The second threshold value may be determined experimentally or by a conventional algorithm in advance. Figure 12 , unlike the first map data LMR, the second map data LMF may have a value of 0 for the pixel PX2 and thus may not include an error in determining the background as the sign LG.

[0092] The grayscale converter 156 may designate pixels corresponding to the flag LG based on the second map data LMF and convert the grayscale of the designated pixels in the first image IMG1 to generate the second image IMG2. In one embodiment, for example, the grayscale converter 156 may designate pixels corresponding to the first binary level (here, 1) in the second map data LMF as pixels corresponding to the flag LG.

[0093] The grayscale converter 156 may generate the second image IMG2 by reducing the grayscale of the pixels corresponding to the logo LG in the first image IMG1. As a result, the brightness of light emitted from the pixels corresponding to the logo LG in consecutive frame periods may be reduced, and afterimages may be effectively prevented.

[0094] Figure 13 is a diagram showing first compensation map data according to an embodiment of the present invention.

[0095] According to an embodiment, the data accumulator 152 may generate the first compensated map data LMR_C1 by applying an increase to a first binary level of the first map data LMR and a decrease to a second binary level. In such an embodiment, the data accumulator 152 may generate the first accumulated data ACR by adding the first compensated map data LMR_C1 to the memory data MRD.

[0096] In such an embodiment, the data accumulator 152 may generate the first accumulated data ACR by adding the first compensated map data LMR_C1 to the memory data MRD instead of directly adding the first map data LMR to the memory data MRD.

[0097] In one embodiment, for example, the increase and the decrease may be the same. In one embodiment, for example, the absolute value of the increase and the absolute value of the decrease may be the same. In one embodiment, for example, the increase may be 1 and the decrease may be 1 (i.e., -1). According to the embodiment, the increase of noise NS over time can be effectively suppressed.

[0098] Figure 14 is a diagram showing first compensation map data according to an alternative embodiment of the present invention.

[0099] Figure 14 The first compensation map data LMR_C2 is Figure 13 The difference of the embodiment of can be that the increase is greater than the decrease. In the embodiment, as Figure 14As shown in FIG, in the first compensation map data LMR_C2, the absolute value of the increase amount may be greater than the absolute value of the decrease amount. In one embodiment, for example, in the first compensation map data LMR_C2, the increase amount may be 2 and the decrease amount may be 1 (ie, -1).

[0100] According to an embodiment, the higher the reliability of the landmark detection algorithm of the landmark detector 151, the better the effect. In such an embodiment, the higher the accuracy of the first map data LMR as a result of the landmark detection algorithm, the better the effect. Figure 14 The embodiment can be compared Figure 13 The embodiment specifies the flag LG at a faster rate.

[0101] Embodiments of a display device and a driving method thereof according to the present invention can effectively prevent afterimages by accurately specifying pixels corresponding to logos.

[0102] The present invention should not be interpreted as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the present invention to those skilled in the art.

[0103] While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit or scope of the invention as defined by the following claims.

Claims

1. A display device, comprising: Pixels; an image converter that generates a second image by correcting the grayscale of the mark in the first image for the pixel and includes a memory; and a data driver for providing a data voltage corresponding to the second image to the pixel; wherein the image converter generates first accumulated data by accumulating first map data corresponding to a marker area larger than the marker in the first image in memory data received from the memory during a plurality of frame periods, generates second accumulated data by scaling the first accumulated data in each refresh cycle, generates third accumulated data by initializing values ​​smaller than a first threshold in the second accumulated data as background values, and designates pixels corresponding to the marker based on second map data corresponding to the third accumulated data, wherein the refresh period corresponds to p frame periods, and p is an integer greater than 1, and The resolution of the unit data corresponding to each pixel in the memory data in the memory is smaller than p.

2. The display device according to claim 1, wherein The image converter includes a landmark detector that detects the landmark area in the first image, and The sign detector generates the first map data in which pixels in the sign area identified as the sign are indicated as a first binary level and pixels in the sign area identified as background are indicated as a second binary level.

3. The display device according to claim 2, wherein: The image converter further includes a data accumulator that generates the first accumulated data, and The data accumulator generates the first accumulated data by accumulating the first map data in the memory data received from the memory.

4. The display device according to claim 3, wherein The data accumulator generates the first accumulated data by adding the first map data to the memory data.

5. The display device according to claim 3, wherein The data accumulator generates first compensated map data by applying an increase to the first binary level of the first map data and a decrease to the second binary level, and generates the first accumulated data by adding the first compensated map data to the memory data. The display device according to claim 5 , wherein: The increase is greater than the decrease.

7. The display device according to claim 3, wherein: The image converter further includes a scaler that generates the second accumulated data by downscaling the first accumulated data at each refresh period.

8. The display device according to claim 7, wherein: The image converter further includes a cropping unit that generates the third accumulated data by initializing the value smaller than the first threshold value in the second accumulated data to the background value, and Wherein the background value is the same as the second binary level.

9. The display device according to claim 8, wherein The memory stores the third accumulated data as the memory data.

10. The display device according to claim 9, wherein The image converter further includes a landmark determination unit generating the second map data, The flag determination unit generates the second map data by replacing values ​​greater than a second threshold value in the third accumulated data with the first binary level and replacing values ​​less than the second threshold value in the third accumulated data with the second binary level.

11. The display device according to claim 10, wherein: The image converter further includes a grayscale converter that generates the second image by specifying the pixels corresponding to the marker based on the second map data and converting the grayscale of the specified pixels in the first image. The grayscale converter designates pixels corresponding to the first binary level in the second map data as the pixels corresponding to the logo.

12. The display device according to claim 11, wherein The grayscale converter generates the second image by reducing the grayscale of the pixels corresponding to the logo in the first image.

13. A method for driving a display device, the method comprising: generating first accumulated data by accumulating first map data corresponding to a marker area larger than the marker in the first image in the memory data during a plurality of frame periods; generating second accumulated data by scaling the first accumulated data in each refresh cycle; generating third accumulated data by initializing a value smaller than a first threshold value in the second accumulated data as a background value; specifying a pixel corresponding to the marker based on second map data corresponding to the third accumulated data; as well as generating a second image by correcting the grayscale of the pixels designated to correspond to the marker in the first image, wherein the refresh period corresponds to p frame periods, and p is an integer greater than 1, and The resolution of the unit data corresponding to each pixel in the memory data is smaller than p.

14. The driving method according to claim 13, further comprising: The first map data is generated in which pixels in the logo area identified as the logo are indicated as a first binary level, and pixels in the logo area identified as a background are indicated as a second binary level.

15. The driving method according to claim 14, wherein: Generating the first accumulated data includes: generating first compensated map data by applying an increase to the first binary level of the first map data and a decrease to the second binary level; and generating the first accumulated data by adding the first compensated map data to memory data, The increase is greater than the decrease.

16. The driving method according to claim 15, wherein: The background value is the same as the second binary level, and The driving method further includes storing the third accumulated data as the memory data.

17. The driving method according to claim 16, further comprising: The second map data is generated by replacing values ​​greater than a second threshold value in the third accumulated data with the first binary level and replacing values ​​less than the second threshold value in the third accumulated data with the second binary level.

18. The driving method according to claim 17, wherein: The generating of the second image includes reducing the grayscale of the designated pixel corresponding to the mark in the first image.

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