Display device

Abstract

To suppress deterioration of a light-emitting element included in a display device.SOLUTION: A display device includes a display panel having a plurality of pixels each including a light-emitting element, and a control part for outputting video data to the display device, the control part including: a frame generation part for generating a luminance emphasis frame in which the luminance of a moving subject in the video data is emphasized, and a black insertion frame in which black is inserted into the subject; and a frame output part for continuously outputting the luminance emphasis frame and the black insertion frame to the display panel.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a display device.

Background Art

[0002] A display device such as an organic EL display adopts a display method in which light continues to be emitted from a light-emitting element such as an OLED continuously during the period from the completion of writing of image data for one frame until the start of writing of the next frame. With this display format, as the subject moves between frames, a motion blur phenomenon occurs in which blurring, afterimages, etc. of the subject are visually recognized by the human eye.

[0003] Patent Document 1 discloses a display device that suppresses the motion blur phenomenon by inserting a black image between image frames and improves the display quality.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When inserting a black image between image frames, it is necessary to increase the luminance of the image frame displayed before the black image in order to maintain the luminance perceived by humans. On the other hand, operating the light-emitting element at high luminance causes factors that accelerate the deterioration of the light-emitting element.

[0006] The present invention has been made in view of the above-described problems, and an object thereof is to provide a display device that suppresses the deterioration of a light-emitting element.

Means for Solving the Problems

[0007] According to one aspect of the present invention, there is provided a display device including a display panel having a plurality of pixels each including a light-emitting element, and a control unit configured to output video data to the display panel. The control unit includes a frame generation unit configured to generate a luminance enhancement frame in which the luminance of a moving subject in the video data is enhanced and a black insertion frame in which black is inserted into the subject, and a frame output unit configured to continuously output the luminance enhancement frame and the black insertion frame to the display panel.

Effect of the Invention

[0008] According to the present invention, deterioration of the light-emitting elements included in the display device can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 4B

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[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Elements having common functions throughout the drawings are denoted by the same reference numerals, and redundant descriptions may be omitted or simplified.

[0011] [First Embodiment] FIG. 1 is a block diagram showing a schematic configuration of a display device 10 according to the present embodiment. The display device 10 includes a video processing unit 11, a timing control unit 12, a video control unit 13, a data driver unit 14, a gate driver unit 15, and a display panel 20.

[0012] The video processing unit 11 receives a data signal DATA including video data. The video data includes a plurality of frame data. Hereinafter, the frame data may be simply described as a frame. The video processing unit 11 generates a data enable signal DE based on the data signal DATA. The video processing unit 11 may generate a vertical synchronization signal, a horizontal synchronization signal, a clock signal, etc., which are not shown. The video processing unit 11 is electrically connected to the timing control unit 12. The video processing unit 11 transmits the data signal DATA and the generated data enable signal to the timing control unit 12.

[0013] The timing control unit 12 receives a data signal DATA from the video processing unit 11. The timing control unit 12 can also receive a data enable signal DE, a vertical synchronization signal, a horizontal synchronization signal, a clock signal, etc. (hereinafter, these signals are referred to as "drive signals") from the video processing unit 11. Based on the drive signals, the timing control unit 12 generates a control signal DCS for driving the data drive unit 14 and a control signal GCS for driving the gate drive unit. The timing control unit 12 is electrically connected to the video control unit 13. The timing control unit 12 transmits the control signal DCS, the control signal GCS, and the data signal DATA to the video control unit 13.

[0014] The video control unit 13 receives the control signal DCS, the control signal GCS, and the data signal DATA from the timing control unit 12. The video control unit 13 converts the data signal DATA into a data signal DATAm. Also, the video control unit 13 converts the control signal DCS and the control signal GCS into a control signal DCSm and a control signal GCSm respectively according to the converted data signal DATAm. The video control unit 13 is electrically connected to the data drive unit 14 and the gate drive unit 15. The video control unit 13 transmits the data signal DATAm and the control signal DCSm to the data drive unit 14. Also, the video control unit 13 transmits the control signal GCSm to the gate drive unit 15. Specific processes executed by the video control unit 13 will be described later.

[0015] The data drive unit 14 receives the data signal DATAm and the control signal DCSm from the video control unit 13. The data drive unit 14 uses the control signal DCSm to convert the data signal DATAm into an analog data voltage for each row. The control signal DCSm may include a source start pulse signal, a source shift clock signal, a source output enable signal, etc. The source start pulse signal controls the start timing of data sampling of a source driver integrated circuit (not shown) included in the data drive unit 14. The source shift clock signal is used to control the data sampling timing in each of the source driver integrated circuits. The source output enable signal controls the output timing of the signal from the data drive unit 14.

[0016] The data driving unit 14 is electrically connected to each of a plurality of pixels 50 included in the display panel 20 via data lines DL1 to DLm. The data driving unit 14 supplies a data voltage to each of the plurality of pixels 50 via the data lines DL1 to DLm. The conversion period and the output period of the data voltage of the data driving unit 14 can be changed by modulating the output width of the data enable signal DE and the output width of the source output enable signal. The data driving unit 14 continuously supplies the data voltage to each of the plurality of pixels 50 via the data lines DL1 to DLm while synchronizing with the output timing of the gate signal described later. The plurality of data voltages supplied to the plurality of pixels 50 respectively correspond to the luminance of the plurality of pixels 50.

[0017] The gate driving unit 15 receives a control signal GCSm from the video control unit. The gate driving unit 15 is electrically connected to the display panel 20 via gate lines GL1 to GLn. The gate driving unit 15 outputs a gate signal to each of the gate lines GL1 to GLn based on the gate control signal GCSm.

[0018] The gate driving unit 15 may include internal circuits (not shown) such as a level shifter, a shift register, a delay circuit, and a flip-flop. The gate driving unit 15 continuously generates control signals such as a gate start pulse signal, a gate shift clock signal, and a gate output enable signal according to the gate control signal GCSm. The gate start pulse signal controls the timing of the start of the operation of a gate driver integrated circuit (not shown) included in the gate driving unit 15. The gate shift clock signal is a signal commonly input to the gate driver integrated circuit and controls the shift timing of a scanning signal (gate signal). The gate output enable signal specifies the timing information of the gate driver integrated circuit. The gate driving unit 15 continuously generates a gate signal by shifting the gate start pulse signal according to the gate shift clock signal. The gate driving unit 15 supplies the generated gate signal to each of the gate lines GL1 to GLn. The gate signal supplied via the gate lines GL1 to GLn activates each of the plurality of pixels 50. The gate driving unit 15 controls the output width of the gate signal based on the output widths of the data enable signal DE and the gate output enable signal.

[0019] The display panel 20 constitutes the display image of the display device 10. A video is provided to the user by continuously outputting a plurality of images via the display panel 20 based on a plurality of frame data. The display panel 20 includes a plurality of pixels 50 arranged in a matrix in each pixel region defined by the intersection of gate lines GL1 to GLn extending in the row direction from the gate driving unit 15 and data lines DL1 to DLm extending in the column direction from the data driving unit 14 (m and n are positive integers, the same applies hereinafter). Each of the plurality of pixels 50 includes a light-emitting element. In the present embodiment, the light-emitting element included in each of the plurality of pixels 50 includes an organic light-emitting diode (OLED). The OLED emits light according to the current flowing between the light-emitting elements. The luminance of the light emitted from the OLED increases almost linearly as the current density flowing between the light-emitting elements increases. On the other hand, the operation of the OLED at high luminance accelerates the deterioration rate of the light-emitting element non-linearly. When the OLED deteriorates due to high-luminance operation, the luminance of the light emitted from the OLED at the same current density decreases. That is, the longer the time the OLED operates at high luminance, the shorter the life of the light-emitting element becomes.

[0020] FIG. 2 is a block diagram showing a schematic configuration of the video control unit 13 in the present embodiment. The video control unit 13 has a function as a motion detection unit that identifies a moving subject between frames based on the differences between a plurality of frames. The video control unit 13 includes a frame storage unit 131, a mask generation unit 133, and a frame processing unit 135.

[0021] The frame memory unit 131 receives the data signal DATA. The data signal DATA includes the frame data F of the video to be displayed on the display device 10 via the display panel 20. The frame memory unit 131 stores the frame data F. The frame data F includes the data of the image frame F(n) to be displayed at the n-th position and the image frame F(n + 1) to be displayed at the (n + 1)-th position. When the video control unit 13 causes the display device 10 to display the image frame F(n) via the display panel 20, the frame memory unit 131 transmits the data corresponding to the image frames F(n) and F(n + 1) to the mask generation unit 133. Hereinafter, the data corresponding to the image frames F(n) and F(n + 1) may be simply described as the image frames F(n) and F(n + 1), respectively.

[0022] The mask generation unit 133 receives the data of the image frames F(n) and F(n + 1) from the frame memory unit 131. The mask generation unit 133 generates a mask frame M(n) based on the data of the image frames F(n) and F(n + 1). Specific processing for generating the mask frame M(n) will be described later. The mask generation unit 133 transmits the generated mask frame M(n) to the frame processing unit 135. The mask generation unit 133 can generate a mask frame for all the frames displayed via the display panel 20.

[0023] The frame processing unit 135 receives the data of the image frame F(n) from the frame storage unit 131. Also, the frame processing unit 135 receives the mask frame M(n) from the mask generation unit 133. The frame processing unit 135 generates a luminance enhancement frame HBF(n) and a black insertion frame BIF(n) corresponding to the image frame F(n) to be displayed at the n-th position based on the image frame F(n) and the mask frame M(n). Specific processing for generating the luminance enhancement frame HBF(n) and the black insertion frame BIF(n) will be described later. The frame processing unit 135 can generate a luminance enhancement frame and a black insertion frame for all frames to be displayed via the display panel 20. The frame processing unit 135 transmits the generated DATAm including the luminance enhancement frame HBF(n) and the black insertion frame BIF(n) to the data driver unit 14.

[0024] FIG. 3 is a block diagram showing a schematic configuration of the mask generation unit 133 in the present embodiment. The mask generation unit 133 includes a difference calculation unit 1331, an absolute value calculation unit 1333, and a comparison unit 1335.

[0025] The difference calculation unit 1331 receives the image frames F(n) and F(n + 1) from the frame storage unit 131. The difference calculation unit 1331 calculates a difference D(n) between the image frame F(n + 1) and the image frame F(n). Specifically, the difference calculation unit 1331 subtracts the corresponding pixel value of the image frame F(n) from the pixel value of one of the image frame F(n + 1). The difference calculation unit 1331 calculates the difference for all pixel values included in the image frame F(n + 1) and the image frame F(n). The difference calculation unit 1331 transmits the calculated difference D(n) to the absolute value calculation unit 1333.

[0026] The absolute value calculation unit 1333 receives the difference D(n) between the image frame F(n + 1) and the image frame F(n) from the difference calculation unit 1331. The absolute value calculation unit 1333 calculates the absolute value ABS(n) of the difference D(n). When the video transitions from the image frame F(n) to the image frame F(n + 1), the portion of the pixels having a relatively large change in pixel value has a relatively large absolute value. On the other hand, when the displayed image transitions from the image frame F(n) to the image frame F(n + 1), the portion of the pixels having a relatively small change in pixel value has a relatively small absolute value. The absolute value calculation unit 1333 transmits the calculated absolute value ABS(n) to the comparison unit 1335.

[0027] The comparison unit 1335 receives the absolute value ABS(n) from the absolute value calculation unit 1333. The comparison unit 1335 compares the absolute value ABS(n) with a predetermined threshold Th and generates a mask frame M(n) based on the result of the comparison. Specifically, the comparison unit 1335 determines whether the absolute value ABS(n) is greater than a predetermined threshold Th. For example, when it is determined that the absolute value corresponding to a certain pixel is greater than the predetermined threshold Th, the comparison unit 1335 assigns "1" to the portion corresponding to the pixel. Also, when it is determined that the absolute value corresponding to another pixel is smaller than the predetermined threshold Th, the comparison unit 1335 assigns "0" to the portion corresponding to the pixel. The comparison unit 1335 compares the absolute values corresponding to all the pixels included in the absolute value ABS(n) with the predetermined threshold Th and assigns "1" or "0" to the portion corresponding to each pixel based on the result of the comparison. The portion corresponding to the pixel to which "1" is assigned has a relatively large absolute value of the difference D(n). Therefore, the comparison unit 1335 determines that the portion corresponding to the pixel to which "1" is assigned is a subject moving between the image frame F(n) and the image frame F(n + 1). On the other hand, the portion corresponding to the pixel to which "0" is assigned has a relatively small absolute value of the difference D(n). Therefore, the comparison unit 1335 determines that the portion corresponding to the pixel to which "0" is assigned is a subject that is not moving between the image frame F(n) and the image frame F(n + 1).

[0028] The comparison unit 1335 generates a mask in which "1" or "0" is assigned to each pixel. The generated mask is used by the frame processing unit 135 as a mask frame M(n) for identifying a moving subject. The mask frame M(n) can be expressed as a binary image. The comparison unit 1335 transmits the generated mask (mask frame M(n)) to the frame processing unit 135.

[0029] Note that when it is determined that there is no moving subject between the image frame F(n) and the image frame F(n + 1), the comparison unit 1335 can generate a mask (mask frame M(n)) in which only "0" is assigned to each pixel.

[0030] As shown in FIG. 3, in the present embodiment, the difference calculation unit 1331 calculates the difference D(n) based on the consecutive image frames F(n) and F(n + 1), but the difference calculation unit 1331 can calculate the difference D(n) based on non-consecutive image frames. For example, the difference calculation unit 1331 can calculate the difference D(n) based on the image frame F(n) displayed at the n-th position and the image frame F(n + 2) displayed at the (n + 2)-th position. That is, the difference calculation unit 1331 can use any first frame and second frame among a plurality of frames to calculate the difference D(n). Further, the difference calculation unit 1331 may calculate the difference D(n) based on the luminance value instead of the pixel value.

[0031] In the present embodiment, as shown in FIG. 3, a predetermined threshold Th is input from the outside of the mask generation unit 133 to the comparison unit 1335. The predetermined threshold Th may be stored in the comparison unit 1335 in advance, or may be stored in a separate storage unit included in the mask generation unit 133. Further, the predetermined threshold Th may be a fixed value or may be variable.

[0032] FIG. 4A is a diagram showing an example of an image frame F(n) processed by the video control unit 13 in the present embodiment. FIG. 4B is a diagram showing an example of a mask frame M(n) generated by the mask generation unit 133 in the present embodiment.

[0033] The frame memory unit 131 transmits, for example, the image frame F(n) shown in FIG. 4A and the image frame F(n + 1) (not shown) to be displayed next to the image frame F(n) to the mask generation unit 133. In this example, when the video displayed on the display device 10 transitions from the image frame F(n) to the image frame F(n + 1), only the person is moving and the background does not change. In the following description, the part of the moving subject (the person in the example shown in FIG. 4A) may be simply described as the "subject". Also, the part of the non-moving subject (the background in the example shown in FIG. 4) may be described as the "background". The absolute value calculation unit 1333 outputs an absolute value higher than that of the background for the subject. On the other hand, the absolute value calculation unit 1333 outputs an absolute value lower than that of the subject for the background. The comparison unit 1335 determines that the person is a moving subject based on the ABS(n) transmitted from the absolute value calculation unit 1333. Also, the comparison unit 1335 determines that the background is a non-moving subject based on the ABS(n). The comparison unit 1335 generates a mask frame M(n) as shown in FIG. 4B based on the ABS(n). In FIG. 4B, for convenience, the subject is represented in white and the background is represented in black. The mask generation unit 133 transmits the generated mask frame M(n) to the frame processing unit 135.

[0034] FIG. 5 is a block diagram showing a schematic configuration of the frame processing unit 135 in the present embodiment. The frame processing unit 135 includes a luminance enhancement unit 1351, a black data insertion unit 1353, and a frame output unit 1355.

[0035] The luminance enhancement unit 1351 receives the image frame F(n) from the frame memory unit 131. Also, the luminance enhancement unit 1351 receives the mask frame M(n) from the mask generation unit 133. The luminance enhancement unit 1351 generates a luminance enhanced frame HBF(n) based on the image frame F(n) and the mask frame M(n). The luminance enhancement unit 1351 corresponds to a frame generation unit for generating the luminance enhanced frame HBF(n).

[0036] Specifically, the luminance enhancement unit 1351 performs masking processing using the image frame F(n) and the mask frame M(n), and extracts the subject from the image frame F(n). Based on the image frame F(n), the luminance enhancement unit 1351 generates an image (frame) in which the luminance of the extracted subject is higher than the luminance of the subject in the image frame F(n). On the other hand, in the generated image, the luminance enhancement unit 1351 maintains the luminance of the background to be the same as that of the background in the image frame F(n). That is, the luminance enhancement unit 1351 generates a luminance enhancement frame HBF(n) in which only the luminance of the subject is increased based on the image frame F(n) and the mask frame M(n). In the generated luminance enhancement frame HBF(n), the background has the same luminance as the background in the image frame F(n). The luminance enhancement unit 1351 transmits the generated luminance enhancement frame HBF(n) to the frame output unit 1355.

[0037] The black data insertion unit 1353 receives the image frame F(n) from the frame storage unit 131. The black data insertion unit 1353 also receives the mask frame M(n) from the mask generation unit 133. The black data insertion unit 1353 generates a black insertion frame BIF(n) based on the image frame F(n) and the mask frame M(n). The black data insertion unit 1353 corresponds to a frame generation unit for generating the black insertion frame BIF(n).

[0038] Specifically, the black data insertion unit 1353 performs a masking process using the image frame F(n) and the mask frame M(n), and extracts the subject from the image frame F(n). In the present embodiment, the black data insertion unit 1353 generates an image (frame) in which black is inserted into the extracted subject based on the image frame F(n). On the other hand, the black data insertion unit 1353 maintains the luminance of the background in the generated image to be the same as the background in the image frame F(n). That is, the black data insertion unit 1353 generates a black insertion frame BIF(n) in which black is inserted only into the subject based on the image frame F(n) and the mask frame M(n). In the generated black insertion frame BIF(n), the background has the same luminance as the background in the image frame F(n). The black data insertion unit 1353 transmits the generated black insertion frame BIF(n) to the frame output unit 1355.

[0039] In the present embodiment, the black data insertion unit 1353 generates an image (frame) in which black is inserted into the subject. However, the color inserted into the subject is not limited to black having the lowest gradation. For example, the black data insertion unit 1353 may generate the black insertion frame BIF(n) using a color (for example, gray) having a luminance higher than that of black having the lowest gradation and lower than that of the subject in the image frame F(n).

[0040] The frame output unit 1355 receives the luminance-enhanced frame HBF(n) from the luminance enhancement unit 1351. Also, the frame output unit 1355 receives the black insertion frame BIF(n) from the black data insertion unit 1353. The frame output unit 1355 transmits the luminance-enhanced frame HBF(n) and the black insertion frame BIF(n) to the data driving unit 14. The video control unit 13 generates control signals DCSm and GCSm to sequentially display the luminance-enhanced frame and the black insertion frame within one frame period for displaying the image frame F(n). The video control unit 13 can generate the control signals DCSm and GCSm such that the sum of the period during which the luminance-enhanced frame HBF(n) is displayed and the period during which the black insertion frame BIF(n) is displayed corresponds to the frame rate of the image frame F(n). For example, when the frame rate of the frame F(n) is 60 fps, the video control unit 13 can generate the control signals DCSm and GCSm such that the sum of the period during which the luminance-enhanced frame HBF(n) is displayed and the period during which the black insertion frame BIF(n) is displayed is 1 / 60 second, which is the period during which the frame F(n) is displayed. Based on the generated DCSm and GCSm, the video control unit 13 controls the data driving unit 14 and the gate driving unit 15 to sequentially display the luminance-enhanced frame HBF(n) and the black insertion frame BIF(n) on the display panel 20.

[0041] FIG. 6 is a flowchart showing the steps executed by the video control unit 13 in the present embodiment.

[0042] In step S601, the video control unit 13 stores the first frame and the second frame among the plurality of frames in the frame storage unit 131.

[0043] In step S602, the video control unit 13 calculates the difference between each pixel between the second frame and the first frame.

[0044] In step S603, the video control unit 13 compares the absolute value of the calculated difference with a predetermined threshold.

[0045] In step S604, the video control unit 13 generates a mask frame (mask image) based on the result of the comparison.

[0046] In step S605, the video control unit 13 generates a luminance enhancement frame (luminance enhancement image) based on the mask image and the first frame.

[0047] In step S606, the video control unit 13 generates a black insertion frame (black insertion image) based on the mask image and the first frame.

[0048] In step S607, the video control unit 13 continuously displays the luminance enhancement image and the black insertion image within one frame period.

[0049] FIG. 7 is a graph showing the temporal change in the luminance of the image frame displayed by the display device 10 in the present embodiment. In this graph, the vertical axis represents the luminance of the light emitted by a predetermined pixel in the image frame. Also, in this graph, the horizontal axis represents time. In the present embodiment, the luminance enhancement frame HBF(n) is displayed on the display device 10 during the period from time t0 to time t1. Next, during the period from time t1 to time t2, the black insertion frame BIF(n) is displayed on the display device 10. The period from time t0 to time t2 is the period for displaying one frame and corresponds to the frame rate for displaying the image frame F(n). For example, when the frame rate of the frame F(n) is 60 fps, the length of the period from time t0 to time t2 is 1 / 60 second. In this graph, the solid line indicates the luminance of an arbitrary pixel among the pixels depicting the subject. Also, in this graph, the dashed-dotted line indicates the luminance of an arbitrary pixel among the pixels depicting the background. For ease of explanation, it is assumed that the luminance of the light emitted from all the pixels in the frame F(n) is equal to B1.

[0050] As shown by the dashed line in FIG. 7, during the period from time t0 to time t2, the pixels included in the background that do not move between the image frame F(n) and the image frame F(n + 1) have a constant luminance B1. That is, the luminance enhancement frame HBF(n) and the black insertion frame BIF(n) have the same luminance in the background.

[0051] On the other hand, as shown by the solid line in FIG. 7, during the period from time t0 to time t2, the luminance of the pixels included in the subject that moves between the image frame F(n) and the image frame F(n + 1) changes. Specifically, during the period from time t0 to time t1, the pixels included in the subject have a luminance B2 that is higher than the luminance B1. Then, during the period from time t1 to time t2, the subject has a luminance lower than the luminance B1. The luminance indicated by the solid line during the period from time t1 to time t2 can be the minimum luminance. The luminance B2 during the period from time t0 to time t1 corresponds to the luminance of the pixels included in the subject of the luminance enhancement frame HBF(n). The luminance indicated by the solid line during the period from time t1 to time t2 corresponds to the luminance of the pixels included in the subject of the black insertion frame BIF(n).

[0052] Human vision recognizes brightness by integrating the luminance over a predetermined time. In this example, during the period from time t0 to time t2, the pixels constituting the moving subject in the image frame F(n) have a constant luminance B1. Here, assume that the integrated value of the luminance of the same pixel in the luminance enhancement frame HBF(n) during the period from time t0 to time t1 is I1. Also, assume that the integrated value of the luminance of the same pixel in the black insertion frame BIF(n) during the period from time t1 to time t2 is I2. According to this embodiment, it can be controlled such that the sum of the integrated value I1 and the integrated value I2 is the same as the integrated value of the luminance B1 during the period from time t0 to time t2. Also, the above control can be performed for all the pixels included in the display panel 20. Controlled in this way, the continuously displayed luminance enhancement frame HBF(n) (time t0 to time t1) and the black insertion frame BIF(n) (time t1 to time t2) are perceived to have the same brightness as the image frame F(n) (time t0 to time t2) in one frame period. That is, a user who continuously visually recognizes the luminance enhancement frame HBF(n) (time t0 to time t1) and the black insertion frame BIF(n) (time t1 to time t2) with the luminance controlled as described above perceives substantially the same brightness as when visually recognizing the image frame F(n) (time t0 to time t2). For example, in the example shown in FIG. 7, assume that one frame period (time t0 to time t2) is 1 / 60 second, and the periods from time t0 to time t1 and from time t1 to time t2 are each 1 / 120 second. Also, assume that the average luminance of the pixels depicting the subject in the image frame F(n) is B1, and the average luminance of the pixels depicting the subject in the luminance enhancement frame HBF(n) is B2. In this case, the luminance B2 can be about twice the luminance B1.

[0053] In addition, when there is no moving subject between frames, the image frame is displayed with a constant average luminance over one frame period (from time t0 to time t2). The frame processing unit 135 generates two image frames having the same average luminance as the luminance enhancement frame HBF(n) and the black insertion frame BIF(n). The frame processing unit 135 transmits the two generated image frames to the data driving unit 14 as the luminance enhancement frame HBF(n) and the black insertion frame BIF(n), respectively.

[0054] Specifically, when there is no moving subject between frames, the mask generation unit 133 generates a mask frame M(n) in which "0" is assigned to all pixels. The luminance enhancement unit 1351 generates a first image frame having the same average luminance as the image frame F(n) based on the generated mask frame M(n). Different from the luminance enhancement frame HBF(n) generated when a moving subject is detected, the generated first image frame does not have a luminance-enhanced portion. Also, the black data insertion unit 1353 generates a second image frame having the same average luminance as the image frame F(n) based on the generated mask frame M(n). Different from the black insertion frame BIF(n) when a moving subject is detected, the second image frame does not have a portion replaced with black. That is, when there is no moving subject between frames, the first image frame generated by the luminance enhancement unit 1351 has the same average luminance as the second image frame generated by the black data insertion unit 1353. Also, the first image frame can be the same frame as the second image frame. In one frame period, the first image frame is displayed first within the one frame period, and then the second image frame is displayed. That is, when there is no moving subject between frames, the light-emitting element is not driven at a high luminance and is driven at the same luminance as when the image frame F(n) is displayed. That is, even when displaying a still image or the like, the degradation of the light-emitting element such as an OLED is suppressed to a minimum.

[0055] According to the present invention, black is inserted only into the portions of a subject that are moving between a plurality of frames. Therefore, the number of light-emitting elements driven at a high luminance is limited to the minimum number necessary to suppress the motion blur phenomenon and improve the display quality. Also, when a still image is displayed, the light-emitting elements are not driven at a high luminance. Therefore, the present invention can suppress the degradation of light-emitting elements such as OLEDs and provide a display device with an extended lifespan.

[0056] [Second Embodiment] Regarding the display device according to the second embodiment of the present invention, differences from the first embodiment will be mainly described with reference to FIGS. 8 to 12.

[0057] FIG. 8 is a block diagram showing the schematic configuration of the video control unit 13 in the present embodiment. The video control unit 13 according to the present embodiment is different from the first embodiment in that it further includes a smoothing unit 134 between the mask generation unit 133 and the frame processing unit 135.

[0058] The smoothing unit 134 receives the mask frame M(n) from the mask generation unit 133. The smoothing unit 134 performs a smoothing process on the mask frame M(n) to smooth the change in luminance values in the boundary region between the subject and the background. Details of the smoothing process will be described later. The smoothing unit 134 transmits the mask frame MS(n) on which the smoothing process has been performed to the frame processing unit 135. The frame processing unit 135 generates a luminance enhancement frame HBF(n) and a black insertion frame BIF(n) based on the mask frame MS(n). The frame processing unit 135 transmits a data signal DATAm including the luminance enhancement frame HBF(n) and the black insertion frame BIF(n) to the data driver unit 14.

[0059] FIG. 9 is a block diagram showing the schematic configuration of the smoothing unit 134 in the present embodiment. The smoothing unit 134 includes a filter 1341, a map generation unit 1343, and an image processing unit 1345.

[0060] Filter 1341 receives the mask frame M(n) generated in the mask generation unit 133. Filter 1341 performs filtering processing on the mask frame M(n). Specifically, for example, filter 1341 acquires the luminance values of one pixel (the pixel of interest) within the mask frame M(n) and the pixels located around the said pixel. Based on the acquired luminance values, filter 1341 acquires the number of pixels emitting black. As an example, filter 1341 acquires the luminance values of the pixels located within a 3×3 range (kernel) including the pixel of interest. Then, based on the acquired luminance values, filter 1341 acquires the number of pixels emitting black within the said 3×3 range. Filter 1341 performs similar processing for all the pixels constituting the mask frame M(n). That is, each pixel is set as the pixel of interest, the luminance values of the pixel of interest and the pixels located around the pixel of interest are acquired, and based on the acquired luminance values, the number of pixels emitting black is acquired. Filter 1341 transmits the number of pixels emitting black obtained for each pixel to the map generation unit 1343.

[0061] Note that filter 1341 can set a larger range as the kernel. For example, filter 1341 can use a 5×5 range or a 7×7 range as the kernel. Also, Filter 1341 can weight each pixel within the kernel. For example, filter 1341 can be configured to relatively increase the weight near the center within the kernel and relatively decrease the weight at the periphery of the kernel. Also, filter 1341 may acquire the number of pixels emitting black based on the pixel values instead of the luminance values.

[0062] The map generation unit 1343 defines the relationship between the number of pixels emitting black (black pixels) transmitted from the filter 1341 and the black density (gray level) of the target pixel. Specifically, the map generation unit 1343 associates the corresponding target pixel with the black density based on the number of input black pixels. The map generation unit 1343 can provide steps to the change in the black density based on a predetermined value N. For example, the number of black pixels located in the 3×3 range including the target pixel can be associated with nine black densities as shown in FIG. 10 respectively. In the example shown in FIG. 10, when the number of black pixels included in the kernel is 0, the corresponding target pixel is associated with a black density of 0% (maximum gray level). Also, when the number of black pixels included in the kernel is 1 to 7, the target pixel is associated with black densities of 12.5% to 87.5% respectively. Further, when the number of black pixels included in the kernel is 8 or 9, the corresponding target pixel is associated with a black density of 100% (minimum gray level). The map generation unit 1343 transmits the result of the association between the target pixel and the black density to the image processing unit 1345.

[0063] The image processing unit 1345 generates a smoothed mask frame MS(n) based on the result of the association between the target pixel and the black density. In the mask frame MS(n) generated by the image processing unit 1345, as shown in FIG. 11, the gray level in the vicinity of the boundary (hereinafter referred to as the "boundary region") between the moving subject and the non-moving subject moving between frames changes gently. The boundary region in the mask frame MS(n) can be represented in grayscale. The image processing unit 1345 transmits the generated mask frame MS(n) to the frame processing unit 135.

[0064] In the present embodiment, as shown in FIG. 9, the predetermined value N is input from outside the smoothing unit 134 to the map generation unit 1343. The predetermined value N may be stored in the map generation unit 1343 in advance, or may be stored in a separate storage unit included in the smoothing unit 134. Further, the predetermined value N may be a fixed value or a variable value.

[0065] The frame processing unit 135 generates a luminance enhancement frame HBF(n) based on the gradation information of each pixel included in the mask frame MS(n). In the luminance enhancement frame HBF(n) generated based on the mask frame MS(n), the luminance of the boundary region changes gently. The change in the luminance of the boundary region can be realized by controlling the luminance of the pixels located in the boundary region based on the gradation information included in the mask frame MS(n).

[0066] Note that the frame processing unit 135 may also generate a black insertion frame BIF(n) based on the gradation information of each pixel included in the mask frame MS(n). In the black insertion frame BIF(n) generated based on the mask frame MS(n), the luminance of the boundary region changes gently.

[0067] The frame processing unit 135 transmits a data signal DATAm including the luminance enhancement frame HBF(n) and the black insertion frame BIF(n) generated based on the mask frame MS(n) to the data driving unit 14.

[0068] FIG. 12 is a flowchart showing the steps executed by the video control unit 13 in the present embodiment.

[0069] In step S1201, the video control unit 13 stores the first frame and the second frame among the plurality of frames in the frame storage unit 131.

[0070] In step S1202, the video control unit 13 calculates the difference between each pixel between the second frame and the first frame.

[0071] In step S1203, the video control unit 13 compares the absolute value of the calculated difference with a predetermined threshold value.

[0072] In step S1204, the video control unit 13 generates a mask frame (mask image) based on the result of the comparison.

[0073] In step S1205, the video control unit 13 executes a smoothing process for smoothing the change in the luminance value of the boundary region between the moving subject portion and the portion other than the subject in the mask image, and generates a smoothed mask image.

[0074] In step S1206, the video control unit 13 generates a luminance enhancement frame (luminance enhancement image) based on the smoothed mask image and the first frame.

[0075] In step S1207, the video control unit 13 generates a black insertion frame (black insertion image) based on the smoothed mask image and the first frame.

[0076] In step S1208, the video control unit 13 continuously displays the luminance enhancement image and the black insertion image within one frame period.

[0077] As described above, the human visual sense recognizes the brightness of a frame based on the integrated value of the luminance per a predetermined time. When the user's viewpoint moves within the frame, in the boundary region between the moving subject and the background between frames, the integrated value of the luminance (brightness perceived by a human) may change abruptly due to the luminance enhancement frame and the black insertion frame. Such an abrupt change may be recognized by the user as flicker, afterimage, etc. of the video. According to the present embodiment, by gently changing the luminance in the boundary region, it is possible to suppress the abrupt change in the integrated value of the luminance in the boundary region. Therefore, the present embodiment can provide a display device that suppresses the occurrence of flicker, afterimage, etc. that can be recognized by the user in the boundary region and further improves the display quality.

[0078] [Third Embodiment] Regarding the display device according to the third embodiment of the present invention, differences from the first embodiment and the second embodiment will be mainly described with reference to FIG. 13.

[0079] FIG. 13 is a block diagram showing a schematic configuration of the display device 10 in the present embodiment. The display device 10 according to the present embodiment is different from the first and second embodiments in that it includes a control unit 16.

[0080] In the first and second embodiments, the video control unit 13 was described as a control unit separate from the timing control unit 12. However, the video control unit 13 does not necessarily have to be provided separately from the timing control unit 12. For example, the display device 10 according to the present embodiment has a control unit 16 configured using one chip. The control unit 16 receives a data signal DATA from the video processing unit 11. Also, the control unit 16 can receive drive signals such as a data enable signal DE from the video processing unit 11. The control unit 16 generates a control signal DCS and a control signal GCS based on the drive signal. The control unit 16 converts the data signal DATA into a data signal DATAm. The data signal DATAm includes a luminance enhancement frame HBF(n) and a black insertion frame BIF(n). The control unit 16 converts the control signal DCS and the control signal GCS into a control signal DCSm and a control signal GCSm, respectively, according to the converted data signal DATAm. The control unit 16 is electrically connected to the data driver unit 14 and the gate driver unit 15. The control unit 16 transmits the data signal DATAm and the control signal DCSm to the data driver unit 14. Also, the control unit 16 transmits the control signal GCSm to the gate driver unit 15. That is, the control unit 16 is composed of one chip and can provide all the functions of the timing control unit 12 and the video control unit 13.

[0081] [Other Embodiments] Each part and each process described in each embodiment can be realized by a processor and a memory that cooperates with the processor. For example, the processor can read a program stored in the memory, execute the program, and operate each part as described in each embodiment. The processor can be included in each part described in each embodiment. The processor can be a CPU or an MPU. Also, the memory that cooperates with the processor can be a non-volatile memory.

[0082] The configurations of each part and the content of signals described in each embodiment are not limited to those described above and can be changed according to the use and purpose. Also, the configurations and signals combining each embodiment are all included in the present invention. That is, the present invention is not limited to the above embodiments and can be modified based on the technical idea of the present invention. For example, the present invention includes a configuration in which the above-described embodiments are organically combined.

Explanation of Signs

[0083] 10 Display device 13 Video control unit 133 Mask generation unit 134 Smoothing unit 135 Frame processing unit 1351 Luminance enhancement unit (frame generation unit) 1353 Black data insertion unit (frame generation unit) 1355 Frame output unit

Claims

1. A display device including: a display panel having a plurality of pixels each including a light-emitting element; and a control unit configured to output video data to the display panel. The control unit includes: a frame generation unit configured to generate a luminance enhancement frame in which the luminance of a moving subject in the video data is enhanced and a black insertion frame in which black is inserted into the subject; and a frame output unit configured to continuously output the luminance enhancement frame and the black insertion frame to the display panel.

2. The display device according to claim 1, wherein the control unit further includes a motion detection unit configured to detect the subject based on a difference between a plurality of frames included in the video data.

3. The display device according to claim 2, wherein the motion detection unit generates a mask frame for specifying the subject based on the difference between the plurality of frames.

4. The motion detection unit: calculates a difference in pixel values between a first frame and a second frame among the plurality of frames for each of the plurality of pixels; compares an absolute value of the difference with a predetermined threshold; and generates the mask frame based on the absolute value and the predetermined threshold.

5. The display device according to claim 4, wherein the mask frame is a binary image generated based on a comparison between the absolute value and the predetermined threshold between the first frame and the second frame.

6. The mask frame: represents a portion having an absolute value greater than the predetermined threshold as the subject; and represents a portion having an absolute value smaller than the predetermined threshold as a portion that does not move between the first frame and the second frame.

7. The display device according to claim 6, wherein the first frame and the second frame are consecutive frames.

8. The display device according to claim 4, wherein the frame generation unit specifies the subject based on the mask frame, and generates the luminance enhancement frame by increasing the luminance of the subject in the first frame.

9. The display device according to claim 8, wherein a portion other than the subject in the luminance enhancement frame has the same luminance as a corresponding portion other than the subject in the first frame.

10. ​ ​ ​ ​ The display device according to claim 4, wherein the frame generation unit identifies the subject based on the mask frame, and generates the black insertion frame by inserting black into the subject in the first frame.

11. The display device according to claim 10, wherein portions other than the subject in the black insertion frame have the same luminance as corresponding portions other than the subject in the first frame.

12. The display device according to claim 4, wherein when no subject exists between the first frame and the second frame, the frame generation unit generates two image frames having the same average luminance as the luminance enhancement frame and the black insertion frame.

13. The display device according to claim 12, wherein the two image frames are the same frame as each other.

14. The display device according to claim 2, wherein the luminance enhancement frame and the black insertion frame are sequentially displayed during a period for displaying one of the plurality of frames.

15. The display device according to claim 14, wherein during the period for displaying one frame, the period during which the luminance enhancement frame is displayed is equal to the period during which the black insertion frame is displayed.

16. The display device according to claim 15, wherein the subject in the luminance enhancement frame has a luminance twice that of the subject in one of the plurality of frames.

17. The display device according to claim 3, wherein the control unit further includes a smoothing unit that smooths a change in luminance value of a boundary region between the subject and portions other than the subject in the mask frame.

18. The display device according to claim 17, wherein the smoothing unit represents the boundary region in grayscale.

19. The display device according to claim 18, wherein the smoothing unit obtains the number of pixels having black based on luminance values or pixel values of a plurality of pixels located in the vicinity of the boundary region, and changes the gradation of the boundary region based on the obtained number of pixels having black.

20. The display device according to claim 19, wherein the frame generation unit generates the luminance enhancement frame in which the luminance value of the boundary region is changed based on the change in gradation.

21. The display device according to claim 19, wherein the frame generation unit generates the black insertion frame in which the luminance value of the boundary region is changed based on the change in gradation.

22. The display device according to any one of claims 1 to 21, wherein the light-emitting element is an organic light-emitting diode.

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