Display device and control method of the same

Abstract

To provide a display device capable of minimizing a difference between the display quality in a case where a high luminance image moves in a long side direction of a light emission area and the display quality in a case where the high luminance image moves in a short side direction of the light emission area.SOLUTION: A display device includes a backlight that has plural light emission areas, each of which has a long side direction and short side direction, arranged in a matrix form, a display panel having plural pixels for the purpose of displaying a motion picture by utilizing light emitted from the backlight, and a control unit that controls the luminance of the backlight in each of the light emission areas. The control unit determines a control parameter concerning the luminance of the backlight so that the display quality in a case where a high luminance image, the luminance of which is higher than that of a peripheral image, out of the motion picture moves in the long side direction and the display quality in a case where the high luminance image moves in the short side direction approach each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a display device and a control method thereof. [Background technology]

[0002] In recent years, display devices that perform local dimming, such as LD (Laser Diode) display devices, have been developed. Such display devices have a backlight that emits light and has a plurality of light-emitting regions each including a plurality of light-emitting elements, and a display panel that faces the backlight and has a plurality of pixels that each control the amount of transmission of light emitted from the light-emitting panel.

[0003] In some cases, the display device displays a moving image in which a bright image region and a dark image region are adjacent to each other on the display panel. In this case, the backlight emission region corresponding to the bright image region on the display panel is adjacent to the backlight emission region corresponding to the dark image region on the display panel.

[0004] In the above-mentioned case, if the difference in luminance between adjacent light-emitting regions is large, the difference in black level between the images corresponding to the adjacent light-emitting regions becomes easily visible, and the display quality of the moving image deteriorates. The difference in black level between adjacent images caused by the difference in luminance between the adjacent light-emitting regions is generally called the halo phenomenon.

[0005] In order to suppress the deterioration of the display quality of moving images caused by the halo phenomenon, when a bright image area and a dark image area are adjacent to each other on a display panel, the luminance of the multiple light-emitting areas is gradually decreased from the bright image area to the dark image area. This smooths the luminance of the multiple light-emitting areas, thereby suppressing the deterioration of the display quality of moving images caused by the halo phenomenon. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP2015-176137A Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned display device, in a display panel with a small number of divided areas for local dimming, i.e., a small number of light-emitting regions, the aspect ratio of each light-emitting region may be large, i.e., the length of the long side of the rectangular light-emitting region may be significantly different from the length of the short side of the rectangular light-emitting region.

[0008] In the above-mentioned case, according to the technology disclosed in Patent Document 1, dark image regions and bright image regions are detected from an input image. In this case, in regions with small dark regions, smoothing of the backlight luminance is suppressed to prevent floating black, and in other regions, smoothing of the backlight luminance is optimized with uniform parameters. However, for example, in the case where the ratio of short side:long side=1:2, if the smoothing parameters in the short side direction and the smoothing parameters in the long side direction are made the same, the spread of the lighting area of ​​the light emitting region in the moving direction of the bright image region of the moving image becomes larger in the long side direction than in the short side direction. Therefore, the display quality of the moving image in the long side direction of the light emitting region is lower than that in the short side direction of the light emitting region.

[0009] As described above, the technology of Patent Document 1 has the following problem when the aspect ratio of each rectangular light-emitting area constituting the backlight that performs local dimming is large. That is, it is not possible to suppress the degradation of display quality that occurs when a high-luminance image that is brighter than the surrounding images moves in the long-side direction of the light-emitting area. Therefore, the display quality when the high-luminance image moves in the long-side direction of the light-emitting area may be significantly different from the display quality when the high-luminance image moves in the short-side direction of the light-emitting area.

[0010] The present disclosure has been made in consideration of the above-mentioned problems. An object of the present disclosure is to provide a display device and a control method thereof that can reduce the difference between the display quality when a high-luminance image moves in the long-side direction of a light-emitting region and the display quality when a high-luminance image moves in the short-side direction of a light-emitting region. [Means for solving the problem]

[0011] The display device of the present disclosure comprises a backlight including a plurality of light-emitting regions arranged in a matrix, each of the plurality of light-emitting regions having a long side direction and a short side direction; a display panel having a plurality of pixels that display moving images using light emitted by the backlight; and a control unit that controls the luminance of the backlight for each of the plurality of light-emitting regions, wherein the control unit determines a control parameter related to the luminance of the backlight so as to bring closer together the display quality when a high-luminance image of the moving image, which has a higher luminance than surrounding images, moves in the long side direction and the display quality when the high-luminance image moves in the short side direction.

[0012] A control method for a display device according to the present disclosure is a control method for a display device including a backlight including a plurality of light-emitting regions arranged in a matrix, each of the plurality of light-emitting regions having a long side direction and a short side direction, a display panel having a plurality of pixels that display moving images by utilizing light emitted by the backlight, and a control unit that controls the luminance of the backlight for each of the plurality of light-emitting regions, The control unit determines a control parameter related to the brightness of the backlight so as to bring closer the display quality when a high-brightness image, which is brighter than surrounding images in the video, moves in the long side direction to the display quality when the high-brightness image moves in the short side direction. [Brief description of the drawings]

[0013] [Figure 1] 1 is a functional block diagram of a display device according to a first embodiment. [Diagram 2] 10A and 10B are diagrams showing a state in which the tip of a high-luminance image moves in one light-emitting region of the display device in accordance with the first embodiment. [Diagram 3] 4 is a diagram showing a mismatch region in the long side direction and a mismatch region in the short side direction within a lighting area in the display device of the first embodiment. FIG. [Figure 4] A diagram showing the lit and unlit areas in multiple light-emitting regions of the backlight when a high-brightness image moves in the short side direction of the light-emitting region in the display device of embodiment 1, and the remaining moving distance of the high-brightness image within the lit areas. [Diagram 5] This figure shows the lit and unlit areas in multiple light-emitting regions of the backlight when a high-brightness image moves in the long side direction of the light-emitting region in the display device of embodiment 1, as well as the remaining moving distance of the high-brightness image within the lit areas. [Figure 6] 11 is a graph showing the mismatch rate of the display device of the first embodiment and the mismatch rate of the display device of the comparative example. [Figure 7] 5 is a diagram showing a mismatch rate when a high-luminance image moves in the short side direction of a light-emitting region in the display device of the first embodiment. FIG. [Figure 8] 5 is a diagram showing a mismatch rate when a high-luminance image moves in the direction of a longer side of a light-emitting region in the display device of the first embodiment. FIG. [Figure 9] 4 is a diagram for explaining a process executed by a control unit of the display device according to the first embodiment. FIG. [Figure 10] 10 is a diagram showing an example of a method for detecting the moving direction of a high-luminance image executed by a moving direction determination unit of a control unit of the display device according to the first embodiment. FIG. [Figure 11A] 1 is a first diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with Embodiment 1 and the position of a high luminance image moving in the short side direction. [Figure 11B] FIG. 2 is a second diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with embodiment 1 and the position of a high luminance image moving in the short side direction. [Figure 12A] 1 is a first diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with Embodiment 1 and the position of a high luminance image moving in the long side direction. [Figure 12B]13 is a second diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with Embodiment 1 and the position of a high luminance image moving in the long side direction. FIG. [Figure 13A] 13 is a first diagram showing the relationship between the lighting rate of each light-emitting region of the display device in accordance with the second embodiment and the position of a high-luminance image moving in the short side direction. FIG. [Figure 13B] FIG. 11 is a second diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with the second embodiment and the position of a high luminance image moving in the short side direction. [Figure 13C] FIG. 11 is a third diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with the second embodiment and the position of a high luminance image moving in the short side direction. [Figure 14A] 13 is a first diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with the second embodiment and the position of a high luminance image moving in the long side direction. FIG. [Figure 14B] FIG. 11 is a second diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with the second embodiment and the position of a high luminance image moving in the long side direction. [Figure 14C] FIG. 11 is a third diagram showing the relationship between the lighting rate of each light emitting region of the display device in accordance with the second embodiment and the position of a high luminance image moving in the long side direction. [Figure 15] FIG. 11 is a diagram for explaining a process executed by a control unit of the display device according to the third embodiment. [Figure 16] FIG. 13 is a diagram for explaining a process executed by a control unit of the display device according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a display device according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will not be repeated.

[0015] (Embodiment 1) The display device of the first embodiment will be described with reference to FIGS.

[0016] FIG. 1 is a functional block diagram of a display device 10 according to the first embodiment.

[0017] As shown in FIG. 1, the display device 10 includes a backlight BL, a display panel DP, and a control unit CT.

[0018] The display panel DP has a horizontally long rectangular outline when viewed from the front. The display panel DP has a plurality of pixels PX that display moving images using light emitted by a backlight BL. The pixels PX are arranged in a matrix. Each of the pixels PX has a vertically long rectangular shape and is the same size.

[0019] In this embodiment, the display panel DP is a liquid crystal display panel having a liquid crystal layer that changes its alignment state by application of a voltage. However, the display panel DP may be any panel as long as it can display an image by changing the aperture ratio of pixels that transmit light emitted by the backlight BL. The resolution of the matrix-shaped pixels PX included in the display panel DP is higher than the resolution of the light-emitting regions LE included in the backlight BL.

[0020] The backlight BL has a horizontally long rectangular outline when viewed from the front. The backlight BL includes a plurality of light-emitting areas LE arranged in a matrix. Each of the plurality of light-emitting areas LE has a long side direction and a short side direction. In this embodiment, each of the plurality of light-emitting areas LE has a vertically long rectangle and has the same size. The long side direction of each of the plurality of light-emitting areas LE extends along the short side direction of the rectangular outline of the backlight BL.

[0021] Hereinafter, in this specification, unless otherwise specified, the short side direction means the short side direction of the light emitting area LE, and the long side direction means the long side direction of the light emitting area LE. The light emitting area LE is each area whose lighting rate can be independently controlled by the control unit CT and is arranged in a matrix in the backlight BL.

[0022] The short side direction of each of the multiple light emitting regions LE extends along the short side direction of the rectangular outline of the backlight BL. Each of the multiple light emitting regions LE includes multiple light emitting elements, such as LDs (Laser Diodes) or LEDs (Light Emitting Diodes), arranged in a matrix. The multiple light emitting regions LE emit light with substantially the same luminance.

[0023] The control unit CT is called a controller. The control unit CT is composed of a processor or a dedicated circuit that controls the backlight BL and the display panel DP based on a built-in program. The control unit CT independently controls the lighting rate of each of the multiple light-emitting areas LE and the light transmittance of each of the multiple pixels PX.

[0024] Specifically, the control unit CT controls the voltage applied to the light-emitting elements arranged in a matrix in each of the light-emitting regions LE, thereby controlling the luminance of the backlight in each of the light-emitting regions, for example, the luminance of each of the light-emitting elements, so that the control unit CT can control the lighting rate of each of the light-emitting regions LE.

[0025] In addition, the control unit CT controls the aperture ratio of each of the pixels PX by controlling the orientation of the liquid crystal of each of the pixels PX. As a result, the control unit CT can control the gradation of each of the pixels. Specifically, the control unit CT includes a video gradation determination unit 1, a backlight illumination rate determination unit 2, and a movement direction linking parameter control unit 3.

[0026] The video gradation determination unit 1 determines the gradation of each of the multiple pixels PX of the display panel DP based on an input video signal received from outside the display device 10. The backlight lighting rate determination unit 2 determines the lighting rate of each of the multiple light emitting areas LE of the backlight BL based on an input video signal received from outside the display device 10. The lighting rate is represented as the ratio of the actual output luminance to the rated maximum luminance of the light emitting area LE.

[0027] The movement direction linked parameter control unit 3 includes a movement direction detection unit 3A and a parameter control unit 3B. The movement direction detection unit 3A detects the movement direction of the high brightness image H (see FIG. 3) based on the lighting rate determined by the backlight lighting rate determination unit 2. The parameter control unit 3B determines a control parameter (a rate of change in the lighting rate) of the backlight BL related to brightness according to the movement direction of the high brightness image H detected by the movement direction detection unit 3A.

[0028] In the present embodiment, the control parameter is, for example, the rate of change of the lighting rate of each of the plurality of light-emitting areas LE. In this case, the control unit CT can change the switching speed from the off state to the on state of each of the plurality of light-emitting areas LE.

[0029] In the second embodiment described later, the control parameters are, for example, each filter coefficient constituting a matrix of a smoothing filter for a plurality of luminous regions LE. Details of this will be described in the second embodiment.

[0030] FIG. 2 is a diagram showing a state in which the leading edge of a high-luminance image H moves in one light emitting area LE among the plurality of light emitting areas LE of a backlight BL of display device 10 according to the first embodiment.

[0031] In this specification, the high-brightness image H means an image having a higher brightness than the surrounding images adjacent to the high-brightness image H. The surrounding images are a plurality of images surrounding the high-brightness image H. The high-brightness image H moves along one or more light-emitting regions LE. Therefore, in each of the following figures, only the outline of the high-brightness region H is drawn with an encircling line superimposed on one or more light-emitting regions LE. Also, the high-brightness region H is the white area within the encircling line in each figure indicated by the reference symbol H.

[0032] In FIG. 2, the light emitting area LE is lit, and is therefore referred to as a lit area. When the light emitting area LE is unlit, it is referred to as an unlit area. In FIG. 2, the high luminance image H is a white area on the left side of the light emitting area LE. The gray area on the right side of the light emitting area LE is an area with a lower luminance than the high luminance image H. In FIG. 2, the high luminance image H is scheduled to move within the light emitting area LE by a remaining movement distance D in the direction of the short side of the light emitting area LE. In FIG. 2, the aspect ratio of the light emitting area LE is assumed to be 1:1.

[0033] In this specification, for a specific light-emitting area LE at a position corresponding to the end of the movement direction M of a high-brightness image H, which has a higher brightness than the surrounding images in the video, among the multiple light-emitting areas LE, the mismatch rate is defined as the product of the remaining movement distance D of the high-brightness image H and the lighting rate.

[0034] The remaining movement distance D is the distance D in the movement direction M, as shown in Fig. 2. As described above, in this specification, the lighting rate is the ratio of the actual output luminance to the rated maximum luminance of the light emitting area LE. More specifically, the maximum luminance of the light emitting area LE is the luminance of the entire light emitting area LE when all of the multiple light emitting elements contained in the light emitting area LE are caused to emit light at maximum output. Moreover, the actual output luminance is the luminance of the light emitting area LE when the display panel DP is displaying a moving image.

[0035] FIG. 3 is a diagram showing a mismatch region in the short side direction of the luminescent region LE and a mismatch region in the long side direction of the luminescent region LE in a lighted area in the display device 10 of the first embodiment.

[0036] As can be seen from Figure 3, the area in one light-emitting area LE where the tip of the high-brightness image H is expected to move is the mismatch area. The area of ​​the mismatch area differs between when the high-brightness image H moves in the long-side direction of the light-emitting area LE and when the high-brightness image H moves in the short-side direction of the light-emitting area LE. Therefore, the area of ​​the area where the halo phenomenon occurs differs between when the high-brightness image H moves in the long-side direction of the light-emitting area LE and when the high-brightness image H moves in the short-side direction of the light-emitting area LE.

[0037] Fig. 4 is a diagram showing lit areas and unlit areas in multiple light-emitting regions LE when high-luminance image H moves in the short-side direction of light-emitting region LE, and the remaining moving distance D of high-luminance image H in the lit areas, in display device 10 of embodiment 1. Fig. 5 is a diagram showing lit areas and unlit areas in multiple light-emitting regions LE when high-luminance image H moves in the long-side direction of light-emitting region LE, and the remaining moving distance D of high-luminance image H in the lit areas, in display device 10 of embodiment 1.

[0038] As can be seen by comparing FIG. 4 and FIG. 5, the mismatch rate is different when the high-luminance image H moves in the short-side direction of the light-emitting area LE and when the high-luminance image H moves in the long-side direction of the light-emitting area LE. In particular, when the aspect ratio of each light-emitting area LE is large, that is, the longer the length of the light-emitting area LE in the long-side direction relative to the length of the light-emitting area LE in the short-side direction, the greater the difference between the mismatch rate in the short-side direction and the mismatch rate in the long-side direction. In this case, a decrease in display quality occurs when the high-luminance image H moves in the long-side direction of the light-emitting area LE. Therefore, it is preferable to make the mismatch rate in the long-side direction of the light-emitting area LE closer to the mismatch rate in the short-side direction of the light-emitting area LE.

[0039] FIG. 6 is a graph showing the mismatch rate of the display device 10 of the first embodiment and the mismatch rate of the display device of the comparative example. In FIG. 6, the vertical axis represents the mismatch rate, and the horizontal axis represents time. Note that the graph in FIG. 6 is a composite graph of graph (1) in FIG. 7 and graphs (4) and (5) in FIG. 8, which will be described later.

[0040] In the display device 10 of the present embodiment, the control unit CT determines the control parameters of the backlight BL so as to bring the display quality when the high-luminance image H moves in the long-side direction closer to the display quality when the high-luminance image H moves in the short-side direction. Therefore, it is possible to reduce the difference between the display quality when the high-luminance image H moves in the long-side direction and the display quality when the high-luminance image moves in the short-side direction.

[0041] In this embodiment, the control unit CT determines a control parameter of the backlight BL so as to bring the mismatch rate when the high-luminance image H moves in the long side direction closer to the mismatch rate when the high-luminance image H moves in the short side direction. In this embodiment, the control parameter is the change speed of the lighting rate of a specific light-emitting area LE at a position corresponding to the leading end of the high-luminance image H in the moving direction, which has a higher luminance than the surrounding images in the moving image.

[0042] More specifically, the control unit CT executes control as indicated by the white arrow in FIG. 6. That is, the control unit CT brings the mismatch rate when the high-luminance image H moves in the long-side direction of the specific light-emitting area LE closer to the mismatch rate when the high-luminance image H moves in the short-side direction of the specific light-emitting area LE. Specifically, the control unit CT slows down the change speed of the lighting rate of the specific light-emitting area LE when the high-luminance image H moves in the long-side direction. This improves the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE, thereby reducing the difference between the display quality when the luminance image H moves in the long-side direction and the display quality when the high-luminance image H moves in the short-side direction. Therefore, the display quality of the moving image is improved overall.

[0043] Fig. 7 is a diagram showing the mismatch rate when a high-luminance image H moves in the short-side direction of a light-emitting region LE in display device 10 of embodiment 1. In Fig. 7, the aspect ratio of light-emitting region LE is "a". Fig. 8 is a diagram showing the mismatch rate when a high-luminance image H moves in the long-side direction of a light-emitting region LE in display device 10 of embodiment 1. In Fig. 8, the aspect ratio of light-emitting region LE is "2a". In Figs. 7 and 8, the numbers in each light-emitting region LE indicate the lighting rate.

[0044] The smaller aspect ratio is used as the standard for normalization, and the degree of mismatch in the area of ​​the lit area of ​​the luminous region LE corresponding to the end of the high-brightness image H is calculated as a mismatch rate using the following formula.

[0045] Mismatch rate = lighting rate of the light-emitting area LE corresponding to the leading end in the moving direction of the high-brightness image H × remaining moving distance D of the high-brightness image H in the light-emitting area LE The lighting rate of the light emitting region LE corresponding to the end of the high luminance image H is determined according to the maximum luminance of the high luminance image H. In the case where the end of the high luminance image H moves by a distance a in time T, in (1) of FIG. 7 and (3) of FIG. 8, when the tip of the high luminance image H enters the light emitting region LE, the light emitting region LE is lit with a lighting rate of 100%, so the mismatch rate becomes high. This reduces the display quality of the display panel DP. However, if the lighting speed is reduced as in (2) of FIG. 7 and (4) of FIG. 8, the display quality of the display panel DP can be improved.

[0046] However, in the case of a light-emitting area LE with a large aspect ratio, that is, in the case of a light-emitting area LE in which the length in the long side direction and the length in the short side direction are significantly different, the mismatch rate varies greatly depending on the moving direction of the high-luminance image H. For example, when comparing (2) of FIG. 7 with (4) of FIG. 8, the lighting speed (a / T) is the same in both cases. However, in (2) of FIG. 7, the mismatch rate is 0 at time T, whereas in (4) of FIG. 8, the mismatch rate remains high even at time T.

[0047] Therefore, when the high-luminance image H moves in the direction of the long side of the luminance region LE, the lighting speed (a / 2T) of the luminance region LE is slowed down as shown in (5) of Fig. 8. This makes it possible to reduce the mismatch rate at time T. Therefore, by detecting the direction of movement of the high-luminance image H and controlling local dimming according to the detected direction of movement and the aspect ratio of the luminance region LE, it is possible to improve the display quality of the display panel DP.

[0048] In display device 10 of the present embodiment, control unit CT executes control as shown in Fig. 7 and Fig. 8. Specifically, when a high-luminance image moves in the long-side direction of a specific light-emitting area LE, control unit CT slows down the switching speed of the specific light-emitting area LE from an off state to a on state compared to when the high-luminance image moves in the short-side direction of the specific light-emitting area LE.

[0049] More specifically, the backlight lighting rate determination unit 2 determines the control parameter (the rate of change of the lighting rate) of the backlight BL so that the switching speed from the off state to the on state of the specific light-emitting area LE in the long side direction is slower than that in the short side direction. This makes the mismatch rate when the high-luminance image H moves in the long side direction of the specific light-emitting area LE closer to the mismatch rate when the high-luminance image H moves in the short side direction of the specific light-emitting area LE.

[0050] According to the control of the control unit CT, the switching speed from the off state to the on state is changed, so that the mismatch rate when the high-luminance image H moves in the long-side direction of the light-emitting area LE can be made closer to the mismatch rate when the high-luminance image H moves in the short-side direction of the light-emitting area LE.

[0051] FIG. 9 is a diagram for explaining the process executed by the control unit CT of the display device 10 according to the first embodiment.

[0052] 9, in step S1, movement direction detection unit 3A detects the movement direction of high-luminance regions H in each light-emitting region LE. Then, in step S2, movement direction detection unit 3A transmits a signal capable of specifying the number Cv of light-emitting regions LE in which the high-luminance image H is moving in the long-side direction and the number Ch of light-emitting regions LE in which the high-luminance image H is moving in the short-side direction to parameter control unit 3B.

[0053] In step S3, in order to determine whether the high-brightness image H is moving in the long-side direction, the parameter control unit 3B determines whether the number Ch of light emitting regions LE in which the high-brightness image H is moving in the short-side direction is zero.

[0054] In step S3, it may be determined that the number Ch of light emitting regions LE in which the high luminance image H has moved in the short side direction is zero. In this case, in step S4, the parameter control unit 3B assumes that the high luminance image H has not moved in the short side direction of any light emitting region LE, and sets the control parameters for the long side direction.

[0055] On the other hand, in step S3, it may be determined that the number Ch of light emitting regions LE in which the high luminance image H is moving in the short side direction is not zero. In this case, in step S5, the parameter control unit 3B determines whether the number Cv of light emitting regions LE in which the high luminance image H is moving in the long side direction is zero in order to determine whether the high luminance image H is moving in the long side direction of the light emitting region LE.

[0056] In step S5, it may be determined that the number Cv of light emitting regions LE in which the high luminance image H has moved in the long side direction is zero. In this case, in step S6, the parameter control unit 3B determines that the high luminance image H has not moved in the long side direction of any light emitting region LE, and sets the control parameters for the short side direction.

[0057] On the other hand, in step S5, it may be determined that the number Ch of light emitting regions LE in which the high luminance image H has moved in the long side direction is not zero. In this case, in step S5, the parameter control unit 3B considers that the high luminance image H has moved in both the long side direction and the short side direction of the light emitting region LE.

[0058] As a result, the control unit CT determines the control parameter of the backlight BL according to the ratio between the number of specific light-emitting areas LE in which the high-luminance image H moves in the long-side direction and the number of specific light-emitting areas LE in which the high-luminance image H moves in the short-side direction of the specific light-emitting area LE. The control parameter in this case is the rate of change of the lighting rate. Therefore, when the high-luminance image H moves in the combined direction of the long-side direction and the short-side direction of the specific light-emitting area LE, the control parameter (rate of change of the lighting rate) of the backlight BL can be effectively determined.

[0059] FIG. 10 is a diagram showing an example of a method for detecting the movement direction of a high-luminance image H executed by the movement direction detection unit 3A of the control unit CT of the display device 10 according to the first embodiment.

[0060] As shown in (a) of Fig. 10, a high-luminance image H moves from left to right across multiple light-emitting regions LE. At this time, as shown in (b) of Fig. 10, the lighting rate of the light-emitting region LE of the backlight BL changes with the movement of the high-luminance region H in (a) of Fig. 10.

[0061] In this case, as shown in (c) of FIG. 10, when detecting the movement direction of high brightness area H, movement direction detection unit 3A assigns "1" to light emitting areas LE with a lighting rate greater than a predetermined threshold and assigns "0" to light emitting areas LE with a lighting rate equal to or less than a predetermined threshold. In other words, movement direction detection unit 3A binarizes each light emitting area LE. Next, as shown in (d) of FIG. 10, movement direction detection unit 3A calculates the difference Δc between the value of the current frame and the value of the frame one frame before. In addition, movement direction detection unit 3A calculates the difference Δp between the value of the frame one frame before and the value of the frame two frames before.

[0062] The movement direction detection unit 3A executes the process as follows. The coordinates of the issuance area LE to which the "1" of interest in the difference Δp calculated in (d) of Fig. 10 is assigned are set to Δp(x,y), and the issuance area LE with the same coordinates as Δp(x,y) in the difference Δc is set to Δc(x,y). If there is a "1" in Δc(x,y+1) above Δc(x,y), count_TB is increased by +1. If there is a "1" in Δc(x,y-1) below Δc(x,y), count_TB is increased by +1. If there is a "1" in Δc(x+1,y) to the right of Δc(x,y), count_LR is increased by +1. If there is a "1" in Δc(x-1,y) to the left of Δc(x,y), count_LR is increased by +1.

[0063] Next, the methods (1) to (3) of determining the control parameters by the parameter control unit 3B according to the situation will be described.

[0064] Determination method (1): If count_LR>0 and count_TB=0, the high-luminance image H moves only in the short side direction. In this case, the parameter control unit 3B sets the control parameter (lighting speed) A for the short side direction.

[0065] Determination method (2): If count_LR=0 and count_TB>0, the high-luminance image H moves only in the long-side direction. In this case, the parameter control unit 3B sets the control parameter (lighting speed) B for the long-side direction.

[0066] Determination method (3): If count_LR>0 and count_TB>0, the high-luminance image H is moving in a diagonal direction, or high-luminance images H moving in the short side direction and high-luminance images moving in the long side direction are mixed. In this case, the parameter control unit 3B determines the control parameter (lighting speed) C according to the ratio of count_LR to count_TB.

[0067] Specifically, the control parameter Ca=the control parameter A×(count_LR / (count_LR+count_TB)), and the control parameter Cb=the control parameter B×(count_TB / (count_LR+count_TB)). Therefore, the parameter control unit 3B calculates the control parameter C=the control parameter Ca (the control parameter for the short side direction)+the control parameter Cb (the control parameter for the long side direction).

[0068] Figures 11A and 11B are figures for explaining the lighting speed of the light-emitting area LE of (a) a display device of a comparative example and (b) a display device 10 of the present embodiment when a high-brightness image H moves in the short side direction of the light-emitting area LE.

[0069] When the high-brightness image H moves in the short side direction of the light-emitting area LE, if both the turning-on speed and the turning-off speed are high, the switching speed and contrast between the turned-on and turned-off states of the backlight BL become good, as can be seen from the comparison between Figures 11A and 11B.

[0070] Figures 12A and 12B are figures for explaining the lighting speed of the light-emitting area LE of (a) a display device of a comparative example and (b) a display device 10 of the present embodiment when a high-brightness image H moves in the long side direction of the light-emitting area LE.

[0071] When the high-luminance image H moves in the long side direction of the luminous area LE, the turn-off speed of the luminous area LE corresponding to the end in the movement direction of the high-luminance area H is fast, but the turn-on speed of the luminous area LE corresponding to the end in the movement direction of the high-luminance area H is slow. As can be seen from a comparison between Figures 12A and 12B, this makes the lighting operation less noticeable, improving the display quality of the display panel DP caused by changes in the luminance of the luminous area LE.

[0072] (Embodiment 2) Display device 10 of embodiment 2 will be described with reference to Figures 13A to 13CB and Figures 14A to 14C. Note that, in the following, description of the same points as display device 10 of embodiment 1 will not be repeated. Display device 10 of the present embodiment differs from display device 10 of embodiment 1 in the following points.

[0073] Figures 13A to 13C are first to third diagrams, respectively, showing the relationship between the lighting rate of each light-emitting region LE of display device 10 of embodiment 2 and the position of high-luminance image H moving in the short side direction. Figures 14A to 14C are first to third diagrams, respectively, showing the relationship between the lighting rate of each light-emitting region LE of display device 10 of embodiment 2 and the position of high-luminance image H moving in the long side direction.

[0074] In the present embodiment, the control unit CT uses different filter coefficients constituting the matrix of the smoothing filter as control parameters for movement in the long side direction of the light emitting area LE and movement in the short side direction of the light emitting area LE. In other words, according to display device 10 of the present embodiment, as shown in Figures 13A to 13C and 14A to 14C, the control unit CT changes the degree of smoothing in the smoothing process of multiple light emitting areas LE.

[0075] In this embodiment as well, the control unit CT determines the control parameters of the backlight BL so as to bring the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE closer to the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE. However, the process executed by the control unit CT in this embodiment is different from the process executed by the control unit CT in embodiment 1. In this embodiment, when the tip of the high-luminance image H moves in the long-side direction of the light-emitting area LE, the control unit CT increases the degree of smoothing in the smoothing process of the multiple light-emitting areas LE compared to when the high-luminance image H moves in the short-side direction of the light-emitting area LE. To this end, the control unit CT determines the control parameters (filter coefficients) of the multiple light-emitting areas LE.

[0076] More specifically, the image gradation determination unit 1 determines the control parameters (filter coefficients) of the backlight BL so as to increase the degree of smoothing in the smoothing process of the multiple light-emitting areas LE at a position corresponding to a specific light-emitting area LE and at positions in the vicinity thereof. This also makes it possible to reduce the difference in display quality between when the high-luminance image H moves in the long-side direction and when the high-luminance image H moves in the short-side direction.

[0077] The control unit CT determines a control parameter (filter coefficient) of the backlight BL according to the ratio between the number of specific light-emitting areas LE in which the high-brightness image H moves in the long-side direction and the number of specific light-emitting areas LE in which the high-brightness image H moves in the short-side direction of the specific light-emitting area LE.

[0078] According to the above control of the control unit CT, when the high-luminance image H moves in a composite direction of the long side direction and the short side direction of the light emitting area LE, the control parameters (filter coefficients) of the backlight BL can be effectively determined.

[0079] (Embodiment 3) Display device 10 according to the third embodiment will be described with reference to Fig. 15. Note that, in the following, description of the same points as display device 10 according to the first embodiment will not be repeated. Display device 10 according to the present embodiment differs from display device 10 according to the first or second embodiment in the following points.

[0080] FIG. 15 is a diagram for explaining the process executed by the control unit CT of the display device 10 according to the third embodiment.

[0081] In the present embodiment as well, the control unit CT determines the control parameters of the backlight BL so as to bring the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE closer to the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE. However, as shown in Fig. 15, the display device 10 of the present embodiment differs from the display device 10 of the first embodiment in the following points.

[0082] 15, in scene A where fireworks rise and scene C where the window scrolls in the direction of the white arrow, the control unit CT executes a process to determine the control parameters of the backlight BL (lighting speed in embodiment 1, filter coefficient in embodiment 2). However, in scene B where the moon and clouds in the night sky are stationary, the control unit CT does not execute a process to determine the control parameters of the backlight BL.

[0083] That is, the control unit CT determines the control parameters (the lighting speed in the first embodiment or the filter coefficient in the second embodiment) of the backlight BL on the condition that the high-luminance image H moves in the same direction by a distance greater than a predetermined value. By this determination, also in this embodiment, the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE is made closer to the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE.

[0084] In this embodiment, the mismatch rate when the high-luminance image H moves in the long-side direction of the specific light-emitting region LE may be made to approach the mismatch rate when the high-luminance image H moves in the short-side direction of the specific light-emitting region LE. According to the control of this control unit CT, the mismatch rate when the high-luminance image H moves in the long-side direction of the specific light-emitting region LE is made to approach the mismatch rate when the high-luminance image H moves in the short-side direction of the specific light-emitting region LE only when necessary. Therefore, the control burden on the control unit CT can be reduced.

[0085] Furthermore, the control unit CT may increase the degree of smoothing of the multiple light-emitting regions LE when the high-brightness image H moves in the long-side direction compared to when the high-brightness image H moves in the short-side direction, on the condition that the high-brightness image H moves in the same direction by a distance greater than a predetermined value. In this case as well, the control unit CT determines the filter coefficients of the multiple light-emitting regions LE so as to increase the degree of smoothing of the multiple light-emitting regions LE. According to this control by the control unit CT, the degree of smoothing is increased only when necessary. Therefore, the control burden on the control unit CT can be reduced.

[0086] (Embodiment 4) Display device 10 of embodiment 4 will be described with reference to Fig. 16. Note that, in the following, description of the same points as display device 10 of embodiment 1 will not be repeated. Display device 10 of the present embodiment differs from display device 10 of embodiments 1 to 3 in the following points.

[0087] FIG. 16 is a diagram for explaining the process executed by the control unit CT of the display device 10 according to the fourth embodiment.

[0088] 16, the display panel DP changes from a state in which the high-luminance image H moves in the up-down direction of the display panel DP in scene A to a state in which the high-luminance image H moves in the left-right direction of the display panel DP in scene B. In this case, the display panel DP changes from a state in which the high-luminance image H moves in the long-side direction of a specific light-emitting region LE to a state in which the high-luminance image H moves in the short-side direction of the specific light-emitting region LE.

[0089] 16, the display panel DP changes from a state in which the high-luminance image H moves in the left-right direction of the display panel DP in scene B to a state in which the high-luminance image H moves in the up-down direction of the display panel DP in scene C. In this case, the display panel DP changes from a state in which the high-luminance image H moves in the short-side direction of a specific light-emitting region LE to a state in which the high-luminance image H moves in the long-side direction of the specific light-emitting region LE.

[0090] In this embodiment as well, the control unit CT determines the control parameters of the backlight BL so as to bring the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE closer to the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE. However, in switching between the above-mentioned scenes A, B, and C, there are cases where the state in which the high-luminance image H moves in the short-side direction of a specific light-emitting area LE and the state in which the high-luminance image H moves in the long-side direction of a specific light-emitting area LE suddenly switch (within a predetermined time). In this case, in this embodiment, the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE and the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE are gradually brought closer to each other.

[0091] More specifically, as shown by the inclined portion of the graph in Fig. 16, the control parameter in the long side direction and the control parameter in the short side direction are gradually switched. The control unit CT may gradually bring the mismatch rate when the high-luminance image moves in the long side direction of a specific light-emitting area LE closer to the mismatch rate when the high-luminance image moves in the short side direction of the specific light-emitting area LE. Furthermore, the control unit CT may gradually increase the degree of smoothing in the smoothing process of the multiple light-emitting areas LE when the high-luminance image H moves in the long side direction compared to when the high-luminance image H moves in the short side direction. In this case, the control unit CT gradually changes the control parameters (filter coefficients) of the backlight BL.

[0092] According to the above control, it is possible to suppress a decrease in the display quality of the moving image displayed on the display panel DP without making any sudden changes to the moving image. This is because if the display quality when the high-luminance image H moves in the long-side direction of the light-emitting area LE and the display quality when the high-luminance image H moves in the short-side direction of the light-emitting area LE are suddenly brought closer to each other, the state of the moving image displayed on the display panel DP will change suddenly. In general, since viewers of moving images tend to notice sudden changes in the display of moving images, it is considered preferable to change the moving image gradually. [Explanation of symbols]

[0093] BL Backlight LE Light Emitting Area DP display panel PX pixels CT control section 10 Display device

Claims

1. a backlight including a plurality of light-emitting regions arranged in a matrix, each of the plurality of light-emitting regions having a long side direction and a short side direction; a display panel having a plurality of pixels for displaying moving images by utilizing light emitted by the backlight; a control unit that controls the luminance of the backlight in each of the plurality of light-emitting regions, the control unit determines a control parameter related to the luminance of the backlight so as to bring a display quality in a case where a high-luminance image, which is brighter than surrounding images of the moving image, moves in the long side direction closer to a display quality in a case where the high-luminance image moves in the short side direction. Display device.

2. the control unit determines the control parameters related to a lighting rate of each of the plurality of light-emitting regions and a light transmittance of each of the plurality of pixels. The display device according to claim 1 .

3. With respect to a specific light-emitting area at a position corresponding to the leading end of the high-brightness image in the moving direction among the plurality of light-emitting areas, the product of the remaining moving distance of the high-brightness image and the lighting rate of the specific light-emitting area is defined as a mismatch rate, the control unit determines a control parameter of the backlight so as to bring the mismatch rate when the high-brightness image moves in the long-side direction closer to the mismatch rate when the high-brightness image moves in the short-side direction. The display device according to claim 1 .

4. the control unit determines a control parameter of the backlight so as to bring the mismatch rate when the high-brightness image moves in the long-side direction closer to the mismatch rate when the high-brightness image moves in the short-side direction. The display device according to claim 3 .

5. the control unit determines the control parameters of the backlight such that, when the high-luminance image moves in the long-side direction, a switching speed from an off state to a on state of a specific light-emitting area of ​​the plurality of light-emitting areas that is located at a position corresponding to an end of the high-luminance image in the moving direction is slower than when the high-luminance image moves in the short-side direction. The display device according to claim 1 .

6. the control unit determines the control parameter of the backlight so as to slow down a rate of change of a lighting rate of the specific light-emitting region when the high-brightness image moves in the long side direction. The display device according to claim 5 .

7. The control unit determines the control parameters of the backlight so as to increase the degree of smoothing in the smoothing process of the plurality of light emitting areas LE when the high luminance image moves in the long side direction compared to when the high luminance image moves in the short side direction. The display device according to claim 1 .

8. the control unit determines a control parameter of the backlight so as to bring a display quality when the high-brightness image moves in the long side direction closer to a display quality when the high-brightness image moves in the short side direction, on condition that the high-brightness image moves in the same direction by a distance greater than a predetermined value. The display device according to any one of claims 1 to 7.

9. when a state in which the high-brightness image moves in the short side direction and a state in which the high-brightness image moves in the long side direction are switched within a predetermined time, the control unit determines a control parameter of the backlight so as to gradually bring a display quality in which the high-brightness image moves in the long side direction closer to a display quality in which the high-brightness image moves in the short side direction. The display device according to any one of claims 1 to 7.

10. determining a control parameter of the backlight according to a ratio between the number of specific light-emitting areas in which the high-luminance image moves in the long-side direction among the plurality of light-emitting areas and the number of specific light-emitting areas in which the high-luminance image moves in the short-side direction among the plurality of light-emitting areas; The display device according to any one of claims 1 to 7.

11. A control method for a display device including a backlight including a plurality of light-emitting regions arranged in a matrix, each of the plurality of light-emitting regions having a long side direction and a short side direction, a display panel having a plurality of pixels that display moving images using light emitted by the backlight, and a control unit that controls the luminance of the backlight for each of the plurality of light-emitting regions, the control unit determines a control parameter related to the luminance of the backlight so as to bring a display quality in a case where a high-luminance image, which is brighter than surrounding images of the moving image, moves in the long side direction closer to a display quality in a case where the high-luminance image moves in the short side direction. A method for controlling a display device.

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