Display device

Abstract

A display device is provided, comprising: a gain provider configured to set a time point that has passed a set period of time since a first area of an input image was detected as a stationary area as a set time, and to gradually reduce a gain value from the set time; and a grayscale converter configured to generate an output image by applying the gain value to a first area of the input image and a second area including a peripheral area of the first area, wherein the gain provider is configured to set the set period of time differently depending on the magnitude of the grayscale value in the first area.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0046903, filed on April 17, 2020, which is hereby incorporated by reference herein in its entirety. Technical Field

[0002] Aspects of some example embodiments of the present invention are directed to a display device and a driving method thereof. Background Art

[0003] With the development of information technology, the use of display devices that provide a connection medium between users and information has increased. For example, with the development of technology, the use of display devices (such as liquid crystal display devices, organic light emitting display devices, plasma display devices, etc.) has increased.

[0004] The display device may include a plurality of pixels and display frames by combining the light emitted from the pixels. When the plurality of frames are continuously displayed in sequence, the user may recognize the plurality of frames as an image (moving image or still image).

[0005] When displaying a still or static image, a screen saver function that reduces the brightness of the image can be used to prevent or reduce residual images and reduce power consumption. However, if the setting time for reducing the brightness of the image is relatively fast, the user will visually recognize the change in brightness, and if the setting time is relatively slow, the effect of preventing or reducing residual images and reducing power consumption will be reduced.

[0006] The above information disclosed in this Background section is only for enhancement of background understanding and therefore, the information discussed in this Background section does not necessarily constitute prior art. Summary of the Invention

[0007] Aspects according to some example embodiments of the present disclosure include a display device and a driving method thereof, in which a set time may be appropriately set according to a display image in a screen saver function.

[0008] According to some example embodiments of the present invention, a display device may include: a gain providing unit (or gain provider), which sets a time point after a set period of time from a time point when a first area of an input image is detected as a static area as a set time, and gradually reduces the gain value from the set time; and a grayscale conversion unit, which generates an output image by applying the gain value to a first area in the input image and a second area including a peripheral area of the first area, and the gain providing unit may set the set period differently according to the size of the grayscale value in the first area.

[0009] According to some example embodiments, the gain providing unit may set the set period to be shorter as the grayscale value in the first region is larger.

[0010] According to some example embodiments, the gain providing unit may set the set period to be shorter as the average value of the grayscale values in the first region is larger.

[0011] According to some example embodiments, the gain providing unit may set the set period to be shorter as the degree of motion in the second area is greater.

[0012] According to some example embodiments, the gain providing unit may set the set period to be shorter as the degree of motion in the peripheral area is greater.

[0013] According to some example embodiments, the gain providing unit may set the set period to be shorter as the difference between the grayscale value in the first region and the grayscale value in the peripheral region is greater.

[0014] According to some example embodiments, the gain providing unit may set the set period to be shorter as a difference between an average value of grayscale values in the first region and an average value of grayscale values in the peripheral region is larger.

[0015] According to some example embodiments, the gain providing unit may set the set period to be shorter as the load value of the input image is smaller.

[0016] According to some example embodiments, the load value may be a sum value or an average value of grayscale values in the entire region of the input image.

[0017] According to some example embodiments, the gain providing unit may include a still area detection unit that detects a first area of an input image as a still area and provides a grayscale value of the first area; a set period setting unit that sets a set period shorter as the grayscale value in the first area is larger; and a gain generating unit that gradually reduces the gain value from a set time based on the set period.

[0018] According to some example embodiments, the gain providing unit may further include a motion detecting unit that detects a degree of motion in the second region, and the set period setting unit may set the set period shorter as the degree of motion is greater.

[0019] According to some example embodiments, the gain providing unit may further include a grayscale comparing unit that calculates a difference between a grayscale value in the first area and a grayscale value in the peripheral area, and the set period setting unit may set the set period shorter as the difference is greater.

[0020] According to some example embodiments, the gain providing unit may further include a load calculation unit which calculates a sum or average value of grayscale values in the entire area of the input image as a load value, and the set period setting unit may set the set period to be shorter when the load value is smaller.

[0021] A display device according to some example embodiments of the present invention may include: a first pixel that displays a still image portion; and a second pixel that displays a moving image portion. Starting at a first time point after a first period of time has passed since a display start time point of the still image portion, the first pixel may gradually reduce an average brightness of the still image portion, and the second pixel may gradually reduce an average brightness of the moving image portion. The first period of time may be set differently depending on the average brightness of the first pixel at the display start time point.

[0022] According to some example embodiments, as the average brightness of the first pixel at the display start time point is greater, the first period may be set to be shorter.

[0023] According to some example embodiments, the first period may be set to be shorter as the degree of motion of the moving image portion is greater.

[0024] According to some example embodiments, the first period may be set to be shorter as the difference between the average brightness of the still image portion and the average brightness of the moving image portion is greater.

[0025] A driving method for a display device according to some example embodiments of the present invention may include: detecting a first area of an input image as a still area; setting a time point after a set period of time from the time point when the still area is detected as a set time; gradually reducing a gain value from the set time; and generating an output image by applying the gain value to the first area in the input image and a second area including a peripheral area of the first area, and the set period of time may be set differently according to the size of the grayscale value in the first area.

[0026] According to some example embodiments, as the grayscale value in the first region is larger, the set period may be set to be shorter.

[0027] According to some example embodiments, as the degree of motion in the second area is greater, the set period may be set to be shorter. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the inventive concept and are incorporated in and constitute a part of this specification, illustrate aspects of some example embodiments of the inventive concept and together with the description serve to explain the principles of the inventive concept.

[0029] Figure 1is a block diagram for explaining a display device according to some example embodiments of the present invention.

[0030] Figure 2 are circuit diagrams for explaining pixels according to some example embodiments of the present invention.

[0031] Figure 3 are diagrams for explaining operations of a gain providing unit according to some example embodiments of the present invention.

[0032] Figure 4 are diagrams for explaining regions of an input image according to some example embodiments of the present invention.

[0033] Figures 5 to 7 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0034] Figures 8 to 10 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0035] Figures 11 to 13 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0036] Figures 14 to 16 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0037] Figure 17 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, various aspects of some exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be implemented in various different forms and is not limited to the embodiments described herein. The embodiments of the present invention can be used in combination with each other or can be used independently of each other.

[0039] In order to clearly describe the present invention, parts not related to the description are omitted, and the same or similar components are represented by the same reference numerals throughout the specification. Therefore, the above reference numerals may be used in other drawings.

[0040] In addition, for the sake of convenience of description, the size and thickness of each component shown in the drawings are arbitrarily shown, so the present invention is not necessarily limited to the size and thickness shown in the drawings. In the drawings, the thickness may be exaggerated to clearly show layers and regions.

[0041] Figure 1 is a block diagram for explaining a display device according to some example embodiments of the present invention.

[0042] Reference Figure 1 , a display device 10 according to some example embodiments of the present invention may include a timing controller 11, a data driver 12, a scan driver 13, a pixel unit 14, a gain providing unit (or gain provider or gain circuit) 15 and a grayscale conversion unit (or grayscale converter or grayscale conversion circuit) 16.

[0043] The timing controller 11 may receive a grayscale value and a control signal for each input image from an external processor. For example, in the case of a still image, the grayscale values of the input images provided successively in frames may be substantially the same. For example, in the case of a moving image, the grayscale values of the input images provided successively in frames may be substantially different. Furthermore, an image may include both a still image portion and a moving image portion. For example, the grayscale values of the input images provided successively in frames may be substantially the same in the still image portion, but may be substantially different in the moving image portion.

[0044] The gain providing unit 15 may provide a gain value SSG based on the input image. For example, the gain providing unit 15 may set a set time point after a set period of time has passed since the first region of the input image was detected as a stationary region, and gradually decrease the gain value SSG (e.g., in set or predefined increments) from the set time point. For example, the gain providing unit 15 may set the set period of time differently depending on the magnitude of the grayscale value in the first region.

[0045] Grayscale conversion unit 16 can generate an output image by applying gain value SSG to an input image. For example, grayscale conversion unit 16 can generate an output image by applying gain value SSG to a first region within the input image and a second region including a peripheral region of the first region. For example, gain value SSG can be 0 or greater and 1 or less. Gain value SSG can be 0% or greater and 100% or less. In addition, gain value SSG can be expressed in various ways. Grayscale conversion unit 16 can calculate the grayscale value of the output image by multiplying the grayscale value of the input image by gain value SSG. For example, grayscale conversion unit 16 can generate the grayscale value of the output image by reducing the grayscale value of the input image by a ratio based on gain value SSG.

[0046] The timing controller 11 may provide a grayscale value of an output image to the data driver 12. In addition, the timing controller 11 may provide a control signal suitable for the specifications of the data driver 12 and the scan driver 13 to display an output image.

[0047] The data driver 12 may generate data voltages to be supplied to the data lines DL1, DL2, DL3, and DLn using the grayscale values of the output image and a control signal, where n may be an integer greater than 0. For example, the data driver 12 may sample the grayscale values using a clock signal and apply data voltages corresponding to the grayscale values to the data lines DL1 to DLn in units of pixel rows. A pixel row may refer to pixels connected to the same scan line.

[0048] The scan driver 13 may receive a clock signal, a scan start signal, etc. from the timing controller 11 and generate scan signals to be supplied to the scan lines SL1 , SL2 , SL3 , and SLm, where m may be an integer greater than 0.

[0049] The scan driver 13 can sequentially supply a scan signal having an on-level pulse to the scan lines SL1 to SLm. The scan driver 13 can include a scan stage configured in the form of a shift register. The scan driver 13 can generate a scan signal by sequentially transmitting a scan start signal in the form of an on-level pulse to the next scan stage according to the control of a clock signal.

[0050] 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.

[0051] Figure 2 are circuit diagrams for explaining pixels according to some example embodiments of the present invention.

[0052] Reference Figure 2 , the pixel PXij may include transistors T1 and T2 , a storage capacitor Cst, and a light emitting diode LD.

[0053] In the following, a circuit consisting of an N-type transistor will be described as an example. However, those skilled in the art will be able to design a circuit consisting of a P-type transistor by changing the polarity of the voltage applied to the gate terminal. Similarly, those skilled in the art will be able to design a circuit consisting of a combination of a P-type transistor and an N-type transistor. A P-type transistor generally refers to a transistor in which the amount of current conducted increases when the voltage difference between the gate electrode and the source electrode increases in a negative direction. An N-type transistor generally refers to a transistor in which the amount of current conducted increases when the voltage difference between the gate electrode and the source electrode increases in a positive direction. The transistor can be configured in various forms such as a thin film transistor (TFT), a field effect transistor (FET), or a bipolar junction transistor (BJT).

[0054] 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.

[0055] 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.

[0056] The storage capacitor Cst may include a first electrode connected to the gate electrode of the first transistor T1 and a second electrode connected to the second electrode of the first transistor T1 .

[0057] 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 be composed of an organic light emitting diode, an inorganic light emitting diode, a quantum dot / well light emitting diode, etc. Figure 2 , the pixel PXij is illustrated as including one light emitting diode LD as an example. However, according to some example embodiments, the pixel PXij may include a plurality of light emitting diodes connected in series or / and in parallel.

[0058] A first power voltage may be applied to the first power line ELVDDL, and a second power voltage may be applied to the second power line ELVSSL. For example, the first power voltage may be greater than the second power voltage.

[0059] When a scan signal of a turn-on level (here, a logic high level) is applied through the scan line SLi, the second transistor T2 may be turned on. At this time, the data voltage applied to the data line DLj may be stored in the first electrode of the storage capacitor Cst.

[0060] A positive driving current corresponding to the voltage difference between the first and second electrodes of the storage capacitor Cst may flow between the first and second electrodes of the first transistor T1. Thus, the light emitting diode LD may emit light having brightness corresponding to the data voltage.

[0061] Next, 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 be turned off, and the data line DLj and the first electrode of the storage capacitor Cst can be electrically isolated. Therefore, even if the data voltage of the data line DLj changes, the voltage stored in the first electrode of the storage capacitor Cst does not change.

[0062] The embodiment can be applied not only to Figure 2The present invention is not limited to the pixel PXij shown in FIG. 1 , but can also be applied to pixels of other pixel circuits.

[0063] Figure 3 are diagrams for explaining operations of a gain providing unit according to some example embodiments of the present invention.

[0064] Reference Figure 3 , shows the gain value SSG provided from the gain providing unit 15 according to time changes.

[0065] The activation time point tEN may be the time point at which the first area of the input image is detected as a static area. When all or part of the input image is detected as a static area, the screen saver function may be activated to prevent or reduce image retention and power consumption by reducing the brightness of the image as described above. The gain value SSG at the activation time point tEN may have an initial level GI.

[0066] The gain providing unit 15 may set the time point at which the set period pSET has passed since the enable time point tEN as the set time tSET. The gain providing unit 15 may gradually (e.g., in set or predetermined increments) reduce the gain value SSG from the set time tSET. For example, the gain providing unit 15 may gradually reduce the gain value SSG until the gain value SSG reaches the saturation level GSAT.

[0067] The saturation time point tSAT may be a time point at which the gain value SSG reaches the saturation level GSAT. The gain providing unit 15 may maintain the gain value SSG from the saturation time point tSAT.

[0068] The reset time point tRST may be a time point at which it is determined that the first region is no longer a static region. For example, it may be a case where a static image of the first region is converted to another static image or to a moving image. At this time, the gain providing unit 15 may return the gain value SSG to the initial level GI.

[0069] When the setting time tSET is fast (for example, the setting period pSET is relatively short), the user can visually recognize the change in brightness. However, when the setting time tSET is slow (for example, the setting period pSET is relatively long), the effect of preventing or reducing afterimages and reducing power consumption is reduced. Therefore, it is necessary to appropriately set the setting time tSET.

[0070] Figure 4 are diagrams for explaining regions of an input image according to some example embodiments of the present invention.

[0071] The input image IMG1 may include a first area AR1 detected as a static area. For example, the first area AR1 may display a logo, a banner, or the like. For example, the first area AR1 may be a rectangular area surrounding the logo. For another example, the first area AR1 may be an area having a shape matching the outline of the logo.

[0072] The input image IMG1 may include a first area AR1 and a second area AR2 including a peripheral area of the first area AR1. The second area AR2 may be a portion of the input image IMG1. According to some example embodiments, the second area AR2 may be the entire area of the input image IMG1.

[0073] The input image IMG1 may include a second area AR2 and a third area AR3, the third area AR3 including a peripheral area of the second area AR2. The third area AR3 may be the entire area of the input image IMG1. According to some example embodiments, the second area AR2 and the third area AR3 may overlap with each other.

[0074] For example, the first pixel of the pixel unit 14 can display a still image portion in the first area AR1. Furthermore, the second pixel of the pixel unit 14 can display a moving image portion in a peripheral area of the first area AR1 (e.g., the second area AR2 or the third area AR3). Starting from a first time point (set time tSET) after a first period (e.g., set period pSET) has passed since the display start time point of the still image portion (e.g., the enable time point tEN), the first pixel gradually reduces the average brightness of the still image portion, and the second pixel gradually reduces the average brightness of the moving image portion.

[0075] In this case, the first period can be set differently according to the average brightness of the first pixel at the display start time point. For example, when the average brightness of the first pixel at the display start time point is greater, the first period can be set to be shorter (refer to Figures 5 to 7 For example, the first period may be set to be shorter as the degree of motion of the moving image portion is greater (refer to Figures 8 to 10 For example, the first period can be set to be shorter as the difference between the average brightness of the still image portion and the average brightness of the moving image portion is larger (refer to Figures 11 to 13 ).

[0076] Figures 5 to 7 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0077] Reference Figure 5According to some example embodiments of the present invention, the gain providing unit (or gain provider or gain providing circuit) 15a may include a still area detection unit (or still area detector or still area detection circuit) 151, a setting period setting unit (or setting period setter or setting period setting circuit) 152 and a gain generating unit (or gain generator or gain generating circuit) 153.

[0078] The gain providing unit 15a may set the setting period pSETa to be shorter when the grayscale value in the first area AR1 is larger. For example, the gain providing unit 15a may set the setting period pSETa to be shorter when the average value of the grayscale value in the first area AR1 is larger.

[0079] The still area detection unit (or still area detector or still area detection circuit) 151 may detect a first area AR1 of the input image IMG1 as a still area and provide a grayscale value STI of the first area AR1. For example, the still area detection unit 151 may compare the grayscale value of the input image IMG1 of the previous frame period with the grayscale value of the input image IMG1 of the current frame period to detect that the input image IMG1 includes a still area. For example, the still area detection unit 151 may detect, as a still area, the first area AR1 in which the difference between the grayscale value of the input image IMG1 of the previous frame period and the grayscale value of the input image IMG1 of the current frame period is equal to or less than a reference value. According to some example embodiments, the still area detection unit 151 may use a still area detection algorithm according to the prior art.

[0080] The set period setting unit 152 may set the set period pSETa to be shorter as the grayscale value STI in the first area AR1 increases. For example, the set period setting unit 152 may set the set period pSETa to be shorter as the average value of the grayscale value STI in the first area AR1 increases.

[0081] Reference Figure 6When the grayscale value STI is at the first level STI1, the set period setting unit 152 may set the first period pSET1a to the set period pSETa. When the grayscale value STI is at the second level STI2, the set period setting unit 152 may set the second period pSET2a to the set period pSETa. Furthermore, when the grayscale value STI is at the third level STI3, the set period setting unit 152 may set the third period pSET3a to the set period pSETa. In this case, the second level STI2 may be greater than the first level STI1, and the third level STI3 may be greater than the second level STI2. In this case, each of the first level STI1, the second level STI2, and the third level STI3 may be an average value or a sum of the grayscale values STI of the first area AR1.

[0082] In this case, the second period pSET2a may be shorter than the first period pSET1a, and the third period pSET3a may be shorter than the second period pSET2a. The first period pSET1a for the first level STI1, the second period pSET2a for the second level STI2, and the third period pSET3a for the third level STI3 may be pre-stored in a lookup table or the like, or may be calculated by an algorithm.

[0083] The gain generation unit 153 may gradually reduce the gain value SSG from the set time tSET based on the set period pSETa.

[0084] Reference Figure 7 When the gain generation unit 153 receives the setting period pSETa of the first period pSET1a, the gain generation unit 153 may set the first time point tSET1a after the first period pSET1a from the enablement time point tEN as the setting time tSET. When the gain generation unit 153 receives the setting period pSETa of the second period pSET2a, the gain generation unit 153 may set the second time point tSET2a after the second period pSET2a from the enablement time point tEN as the setting time tSET. Furthermore, when the gain generation unit 153 receives the setting period pSETa of the third period pSET3a, the gain generation unit 153 may set the third time point tSET3a after the third period pSET3a from the enablement time point tEN as the setting time tSET. In this case, the first time point tSET1a may be later than the second time point tSET2a, and the second time point tSET2a may be later than the third time point tSET3a.

[0085] The higher the grayscale level of the static area, the more disadvantageous it is in terms of afterimage and power consumption. According to some example embodiments, the higher the grayscale level of the static area, the faster the set time tSET can be set. Therefore, afterimage can be prevented or reduced, and power consumption can be reduced.

[0086] Figures 8 to 10 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0087] Reference Figure 8 , the gain providing unit 15 b according to some example embodiments of the present invention may include a motion detecting unit 154 , a set period setting unit 152 , and a gain generating unit 153 .

[0088] The gain providing unit 15b may set the set period pSETb shorter as the degree of movement of the second area AR2 increases. For example, the gain providing unit 15b may set the set period pSETb shorter as the degree of movement of the peripheral area of the first area AR1 increases.

[0089] The motion detection unit (or motion detector or motion detection circuit) 154 may detect the degree of motion MTI of the second area AR2. For example, the motion detection unit 154 may compare the grayscale value of the input image IMG1 of the previous frame period with the grayscale value of the input image IMG1 of the current frame period to detect the degree of motion MTI of the second area AR2. For example, in the second area AR2, the greater the difference between the grayscale value of the input image IMG1 of the previous frame period and the grayscale value of the input image IMG1 of the current frame period, the greater the degree of motion MTI may be. According to some example embodiments, the motion detection unit 154 may detect the degree of motion MTI of the peripheral area of the first area AR1. According to some example embodiments, the motion detection unit 154 may use a motion degree detection algorithm according to the prior art.

[0090] The set period setting unit 152 may set the set period pSETb to be shorter as the degree of motion MTI is greater. For example, the set period setting unit 152 may set the set period pSETb to be shorter as the degree of motion MTI of the peripheral area of the first area AR1 is greater.

[0091] Reference Figure 9When the motion level MTI is at the first level MTI1, the set period setting unit 152 may set the first period pSET1b as the set period pSETb. When the motion level MTI is at the second level MTI2, the set period setting unit 152 may set the second period pSET2b as the set period pSETb. Furthermore, when the motion level MTI is at the third level MTI3, the set period setting unit 152 may set the third period pSET3b as the set period pSETb. In this case, the second level MTI2 may be greater than the first level MTI1, and the third level MTI3 may be greater than the second level MTI2. For example, the greater the level of the motion level MTI, the greater the difference between the grayscale values of the input image IMG1 in the previous frame period and the grayscale values of the input image IMG1 in the current frame period. For example, for consecutive input images, the user may recognize the input image as a motion image at the first level MTI1, and the user may recognize the input image as a motion image at the third level MTI3.

[0092] In this case, the second period pSET2b may be shorter than the first period pSET1b, and the third period pSET3b may be shorter than the second period pSET2b. The first period pSET1b for the first level MTI1, the second period pSET2b for the second level MTI2, and the third period pSET3b for the third level MTI3 may be pre-stored in a lookup table or the like, or may be calculated by an algorithm.

[0093] The gain generation unit 153 may gradually reduce the gain value SSG from the set time tSET based on the set period pSETa.

[0094] Reference Figure 10 When the gain generation unit 153 receives the setting period pSETb of the first period pSET1b, the gain generation unit 153 may set the first time point tSET1b that has elapsed from the activation time point tEN by the first period pSET1b as the setting time tSET. When the gain generation unit 153 receives the setting period pSETb of the second period pSET2b, the gain generation unit 153 may set the second time point tSET2b that has elapsed from the activation time point tEN by the second period pSET2b as the setting time tSET. Furthermore, when the gain generation unit 153 receives the setting period pSETb of the third period pSET3b, the gain generation unit 153 may set the third time point tSET3b that has elapsed from the activation time point tEN by the third period pSET3b as the setting time tSET. In this case, the first time point tSET1b may be later than the second time point tSET2b, and the second time point tSET2b may be later than the third time point tSET3b.

[0095] According to some example embodiments, when the motion level MIT is large, the user may be insensitive to changes in brightness. Therefore, the user may set the set time tSET to be fast. The faster the set time tSET, the greater the effect of preventing or reducing afterimages and reducing power consumption.

[0096] Figures 11 to 13 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0097] Reference Figure 11 , the gain providing unit 15c according to some example embodiments of the present invention may include a still area detecting unit 151, a grayscale comparing unit 155, a set period setting unit 152, and a gain generating unit 153. Description of the still area detecting unit 151 will be omitted to avoid repetition.

[0098] The gain providing unit 15c may set the setting period pSETc to be shorter as the difference GDI between the grayscale values STI in the first area AR1 and the grayscale values in the peripheral area of the first area AR1 increases. For example, the gain providing unit 15c may set the setting period pSETc to be shorter as the difference GDI between the average value of the grayscale values STI in the first area AR1 and the average value of the grayscale values in the peripheral area of the first area AR1 increases.

[0099] The grayscale comparison unit 155 may calculate a difference GDI between the grayscale values STI in the first area AR1 and the grayscale values in the peripheral area of the first area AR1. For example, the grayscale comparison unit 155 may calculate a difference GDI between the average value of the grayscale values STI in the first area AR1 and the average value of the grayscale values in the peripheral area of the first area AR1.

[0100] The setting period setting unit 152 may set the setting period pSETc to be shorter as the difference value GDI is larger.

[0101] Reference Figure 12When the difference value GDI is at the first level GDI1, the set period setting unit 152 may set the first period pSET1c to the set period pSETc. When the difference value GDI is at the second level GDI2, the set period setting unit 152 may set the second period pSET2c to the set period pSETc. Furthermore, when the difference value GDI is at the third level GDI3, the set period setting unit 152 may set the third period pSET3c to the set period pSETc. In this case, the second level GDI2 may be greater than the first level GDI1, and the third level GDI3 may be greater than the second level GDI2. In this case, the second period pSET2c may be shorter than the first period pSET1c, and the third period pSET3c may be shorter than the second period pSET2c. The first period pSET1c for the first level GDI1, the second period pSET2c for the second level GDI2, and the third period pSET3c for the third level GDI3 may be pre-stored in a lookup table, etc., or may be calculated by an algorithm.

[0102] The gain generation unit 153 may gradually reduce the gain value SSG from the set time tSET based on the set period pSETc.

[0103] Reference Figure 13 When the gain generation unit 153 receives the setting period pSETc of the first period pSET1c, the gain generation unit 153 may set the first time point tSET1c that has elapsed from the activation time point tEN by the first period pSET1c as the setting time tSET. When the gain generation unit 153 receives the setting period pSETc of the second period pSET2c, the gain generation unit 153 may set the second time point tSET2c that has elapsed from the activation time point tEN by the second period pSET2c as the setting time tSET. Furthermore, when the gain generation unit 153 receives the setting period pSETc of the third period pSET3c, the gain generation unit 153 may set the third time point tSET3c that has elapsed from the activation time point tEN by the third period pSET3c as the setting time tSET. In this case, the first time point tSET1c may be later than the second time point tSET2c, and the second time point tSET2c may be later than the third time point tSET3c.

[0104] The greater the grayscale difference between the static area and the peripheral area, the more disadvantageous it is in terms of afterimages. According to some example embodiments, the larger the grayscale difference between the static area and the peripheral area, the faster the set time tSET may be set. Therefore, afterimages can be prevented or reduced, and power consumption can be reduced.

[0105] Figures 14 to 16is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0106] Reference Figure 14 , the gain providing unit (or gain provider or gain providing circuit) 15d according to some example embodiments of the present invention may include a load calculation unit (or load calculator or load calculation circuit) 156, a setting period setting unit (or setting period setter or setting period setting circuit) 152 and a gain generating unit (or gain generator or gain generating circuit) 153.

[0107] The gain providing unit 15d may set the setting period pSETd shorter when the load value LDI of the input image IMG1 is smaller. For example, the load value LDI may be the sum or average value of the grayscale values of the third area AR3 as the entire area of the input image IMG1.

[0108] The load calculation unit 156 may calculate a sum or average value of grayscale values of the entire region of the input image IMG1 as the load value LDI. According to some example embodiments, the load calculation unit 156 may use a load value detection algorithm according to the related art.

[0109] The setting period setting unit 152 may set the setting period pSETd to be shorter as the load value LDI is smaller.

[0110] Reference Figure 15 When the load value LDI is at the first level LDI1, the set period setting unit 152 may set the first period pSET1d to the set period pSETd. When the load value LDI is at the second level LDI2, the set period setting unit 152 may set the second period pSET2d to the set period pSETd. Furthermore, when the load value LDI is at the third level LDI3, the set period setting unit 152 may set the third period pSET3d to the set period pSETd. In this case, the second level LDI2 may be greater than the first level LDI1, and the third level LDI3 may be greater than the second level LDI2. In this case, the second period pSET2d may be longer than the first period pSET1d, and the third period pSET3d may be longer than the second period pSET2d. The first period pSET1d for the first level LDI1, the second period pSET2d for the second level LDI2, and the third period pSET3d for the third level LDI3 may be pre-stored in a lookup table, etc., or may be calculated using an algorithm.

[0111] The gain generation unit 153 may gradually reduce the gain value SSG from the set time tSET based on the set period pSETd.

[0112] Reference Figure 16 When the gain generation unit 153 receives the setting period pSETd of the first period pSET1d, the gain generation unit 153 may set the first time point tSET1d, which is the first period pSET1d after the activation time point tEN, as the setting time tSET. When the gain generation unit 153 receives the setting period pSETb of the second period pSET2d, the gain generation unit 153 may set the second time point tSET2d, which is the second period pSET2d after the activation time point tEN, as the setting time tSET. Furthermore, when the gain generation unit 153 receives the setting period pSETd of the third period pSET3d, the gain generation unit 153 may set the third time point tSET3d, which is the third period pSET3d after the activation time point tEN, as the setting time tSET. In this case, the first time point tSET1d may be faster than the second time point tSET2d, and the second time point tSET2d may be faster than the third time point tSET3d.

[0113] According to some example embodiments, when the load value LDI is small, the user may be insensitive to changes in brightness. Therefore, the user may set the set time tSET to be faster. The faster the set time tSET, the greater the effect of preventing or reducing afterimages and reducing power consumption, or the better the effect of preventing or reducing afterimages and reducing power consumption.

[0114] Figure 17 is a diagram for explaining a gain providing unit according to some example embodiments of the present invention.

[0115] Reference Figure 17 The gain providing unit 15e according to some example embodiments of the present invention may include a still area detection unit (or still area detector or still area detection circuit) 151, a set period setting unit 152, a gain generating unit 153, a motion detecting unit 154, a grayscale comparing unit 155, and a load calculating unit 156. Descriptions of the components described in the above embodiments will be omitted to avoid repetition.

[0116] The setting period setting unit 152 may set the setting period pSETe based on the grayscale value STI, the difference value GDI, the degree of motion MTI, and the load value LDI. For example, the setting period setting unit 152 may determine the setting period pSETe by applying weights corresponding to the setting periods pSETa, pSETb, pSETc, and pSETd and summing the weighted setting periods pSETa, pSETb, pSETc, and pSETd.

[0117] According to the display device and the driving method thereof of the present invention, a setting time can be appropriately set according to a display image in a screen saver function.

[0118] The electronic or electrical devices and / or any other related devices or components according to the embodiments of the present invention described herein can be implemented using any suitable hardware, firmware (e.g., application specific integrated circuits), software, or a combination of software, firmware, and hardware. For example, the various components of these devices can be formed on an integrated circuit (IC) chip or on a separate IC chip. In addition, the various components of these devices can be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. In addition, the various components of these devices can be processes or threads that run on one or more processors, execute computer program instructions in one or more computing devices, and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory that can be implemented in a computing device using a standard memory device (such as, for example, a random access memory (RAM)). The computer program instructions can also be stored in other non-transitory computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). In addition, it should be appreciated by those skilled in the art that, without departing from the spirit and scope of the exemplary embodiments of the present invention, the functions of various computing devices can be combined or integrated into a single computing device, or the functions of a particular computing device can be distributed on one or more other computing devices.

[0119] The aforementioned drawings and the detailed description of the invention described above are merely illustrative of the invention. It will be understood that the invention is disclosed for illustrative purposes only and is not intended to limit the scope of the invention. Therefore, it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible without departing from the scope of the invention. Therefore, the true scope of the invention should be determined by the technical concepts of the claims and their equivalents.

Claims

1. A display device, comprising: a gain provider configured to set a time point at which a set period of time has elapsed from a time point at which a first area of an input image is detected as a still area as a set time, and gradually reduce the gain value from the set time; as well as a grayscale converter configured to generate an output image by applying the gain value to the first region and a second region including a peripheral region of the first region in the input image, wherein the gain provider is configured to set the setting period differently according to the size of the grayscale value in the first area, and The gain value remains unchanged during the set period.

2. The display device according to claim 1, wherein The gain provider is configured to set the set period shorter as the grayscale value in the first area is larger.

3. The display device according to claim 2, wherein: The gain provider is configured to set the set period shorter as the average value of the grayscale values in the first area is larger.

4. The display device according to claim 1, wherein The gain provider is configured to set the set period to be shorter as the degree of motion in the second area is greater.

5. The display device according to claim 1, wherein The gain provider is configured to set the set period to be shorter as the degree of motion in the peripheral area is greater. The display device according to claim 1 , wherein: The gain provider is configured to set the set period shorter as a difference between the grayscale value in the first area and the grayscale value in the peripheral area is larger.

7. The display device according to claim 6, wherein: The gain provider is configured to set the set period shorter as a difference between an average value of the grayscale values in the first area and an average value of the grayscale values in the peripheral area is larger.

8. The display device according to claim 1, wherein The gain provider is configured to set the set period to be shorter as the load value of the input image is smaller.

9. The display device according to claim 8, wherein: The load value is a sum or average value of grayscale values in the entire area of the input image.

10. The display device according to claim 1, wherein The gain provider comprises: a still area detector configured to detect the first area of the input image as the still area and provide the grayscale value of the first area; a set period setter configured to set the set period to be shorter as the grayscale value in the first area is larger; a gain generator configured to gradually reduce the gain value from the set time based on the set period; a motion detector configured to detect a degree of motion in the second area, wherein the set period setter is configured to set the set period shorter as the degree of motion increases; a grayscale comparator configured to calculate a difference between the grayscale value in the first area and the grayscale value in the peripheral area, wherein the set period setter is configured to set the set period shorter as the difference is larger; and The load calculator is configured to calculate a sum or average value of grayscale values in the entire area of the input image as a load value, wherein the set period setter is configured to set the set period shorter as the load value is smaller.

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