JP2016206288A - Display device, control method of display device, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flicker-less display device reducing moving image blur caused by performing black display in a moving image.SOLUTION: The display device comprises: a liquid crystal panel in which a plurality of pixels divided into a first pixel group and a second pixel group are arranged in matrix; and control means for dividing one frame into a first period and a subsequent second period, and controls the luminance of the plurality of pixels. The first pixel group is controlled so that luminance in the first period is larger than luminance in the second period. The second pixel group is controlled so that, when a difference of the corresponding pixels between frames is larger than a predetermined threshold, the luminance in the first period is larger than the luminance in the second period, and when the difference is smaller than the predetermined threshold, the luminance in the first period is smaller than the luminance in the second period.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid crystal display device such as a liquid crystal projector, a liquid crystal display, and a liquid crystal television.

  Unlike an impulse-type display device such as a cathode ray tube (CRT) that emits pulses in one frame, the liquid crystal display device is a hold-type display device in which a display state is held in one frame. The hold-type display device has lower moving image visibility than the impulse-type display device, and image quality deterioration called moving image blur is likely to occur. In Patent Document 1, in order to improve motion blur and improve motion picture visibility, one frame is divided into a plurality of subfields, and black display (black insertion) is performed in one or more subfields. A method of performing display close to an impulse type display device has been proposed.

Japanese Patent No. 4655341

  Displaying black in a moving area in the video is effective for improving video visibility, but in a non-moving area in the video, there is no movement, but the display blinks greatly. It becomes uncomfortable. This is generally called flicker and becomes unpleasant as the area where there is no movement is wide.

  In view of such a problem, an object of the present invention is to provide a display device free from flicker while improving motion blur due to black display in a moving image.

  A display device according to one aspect of the present invention includes a liquid crystal panel in which a plurality of pixels divided into a first pixel group and a second pixel group are arranged in a matrix, and one frame following a first period. Control means for controlling the luminance of the plurality of pixels divided into a second period, wherein the first pixel group has a luminance in the first period larger than that in the second period. The second pixel group is configured such that the luminance of the first period is greater than the luminance of the second period when the difference between corresponding pixels between frames is greater than a predetermined threshold. When the difference is smaller than the predetermined threshold value, the luminance of the first period is controlled to be smaller than the luminance of the second period.

  According to another aspect of the present invention, there is provided a control method for a display device including a liquid crystal panel in which a plurality of pixels divided into a first pixel group and a second pixel group are arranged in a matrix. A method comprising: dividing one frame into a first period and a subsequent second period; comparing a corresponding pixel difference between frames with a predetermined threshold; and a corresponding pixel difference between frames Is greater than a predetermined threshold value, the first pixel group is controlled such that the luminance of the first period is greater than the luminance of the second period, and the second pixel group is When the luminance of the period is controlled to be larger than the luminance of the second period, and when the difference is smaller than the predetermined threshold, the first pixel group has the luminance of the first period Greater than the brightness of the second period Is controlled to the second pixel group and having the steps of: is controlled to be smaller than the luminance of the first luminance is the second period of time.

  According to the present invention, it is possible to provide a display device free from flicker while improving motion blur caused by black display in a moving image.

1 is a block diagram of a liquid crystal projector as an example of a liquid crystal display device according to an embodiment of the present invention. FIG. 2A is a diagram illustrating the luminance characteristics of the impulse display device, and FIG. 2B is a diagram illustrating the luminance characteristics of the liquid crystal display device. FIG. 3A is a diagram illustrating the luminance characteristics of a liquid crystal display device that performs black display in the subfield SFx2, and FIG. 3B is a diagram that illustrates luminance characteristics of the liquid crystal display device that performs black display in the subfield SFx1. It is a flowchart which shows the method of selecting the subfield which performs black display. FIG. 3 is a layout diagram of pixel groups according to the first exemplary embodiment. 6A is a diagram showing an image in which a rectangle is scrolled from left to right by one pixel per frame, and FIG. 6B is a diagram showing an image in which a rectangle is scrolled from top to bottom by one pixel per frame. is there. It is the figure which showed execution of the black display of Example 1. FIG. FIG. 10 is a layout diagram of pixel groups according to the second embodiment. It is the figure which showed execution of the black display of Example 2. FIG. FIG. 10A is an arrangement diagram of the pixel group according to the third or fourth embodiment. FIG. 10B is a layout diagram of the pixel group according to the fourth embodiment. FIG. 11A is a diagram showing execution of black display in the third or fourth embodiment, and FIG. 11B is a diagram showing execution of black display in the fourth embodiment. FIG. 10 is a block diagram of a liquid crystal projector of Example 4. 14 is a flowchart illustrating a method for determining the arrangement of pixel groups in each frame according to the fourth embodiment. It is the figure which showed execution of black display in a fixed field. FIG. 10 is a diagram illustrating execution of black display by arranging pixel groups for vertical movement.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  A liquid crystal projector as an example of the liquid crystal display device of the present invention will be described with reference to FIG. A liquid crystal projector is a projection display device that modulates and drives a liquid crystal panel in accordance with an input signal, and projects (enlarges and projects) an image on a projection surface (such as a screen) (not shown) using light from a light source. However, the liquid crystal display device applicable to the present embodiment includes a liquid crystal display and a liquid crystal television.

  The liquid crystal projector includes an input terminal 101, a video input circuit 102, a video processing circuit 103, a black insertion circuit 104, a panel drive circuit 105, a liquid crystal panel 106, a controller (control means) 107, an operation panel 108, and a remote controller 109. The input signal input to the input terminal 101 is discriminated by the video input circuit 102, and if it is an analog video signal, A / D conversion is performed and subsequent processing is performed. The video processing circuit 103 adjusts a signal input to the panel drive circuit 105 by the controller 107 so that image processing unique to the product or image processing adjusted by the user using the operation panel 108 or the remote controller 109 can be performed. Controlled to be done. The black insertion circuit 104 performs black display. The panel drive circuit 105 drives the liquid crystal panel 106 so that the display image of the liquid crystal projector has an appropriate luminance corresponding to the input signal. A plurality of pixels are arranged in a matrix on the liquid crystal panel 106.

  Unlike an impulse-type display device such as a CRT that emits pulses in one frame shown in FIG. 2A, the liquid crystal display device is driven at a constant luminance over one frame as shown in FIG. 2B. . In a liquid crystal display device, moving image blur is more visually recognized than in an impulse-type display device. Therefore, by driving one frame divided into a subfield for outputting original luminance and a subfield for performing black display by the black insertion circuit 104, driving close to an impulse type display device is obtained.

  3A and 3B, each frame Fx (x = 1, 2,...) Is divided into a subfield SFx1 (first period) and a subsequent subfield SFx2 (second period) to display black. It is a figure which shows the luminance characteristic after correct | amending the luminance characteristic of FIG.2 (b) by performing. FIG. 3A is a diagram showing the luminance characteristics of the liquid crystal display device that performs black display in the subfield SFx2, and FIG. 3B is a diagram that illustrates the luminance characteristics of the liquid crystal display device that performs black display in the subfield SFx1. The controller 107 performs control so that the entire area is constituted by the pixel group 1 that always performs black display in the subfield SFx2 and the pixel group 2 that performs black display by selecting one of the subfields SFx1 and SFx2.

  FIG. 4 is a flowchart illustrating a method of selecting a subfield for performing black display on the pixel group 2 executed by the controller 107, and “S” is an abbreviation for a step. The method of FIG. 4 can be implemented as a program for causing a computer to execute each step. Furthermore, the program may be installed in a liquid crystal projector or a personal computer via a storage medium storing the program, such as a semiconductor memory or an optical disk, the Internet, or a LAN.

  First, the controller 107 calculates a difference amount between the pixel belonging to the pixel group 2 and the previous frame of the pixel, and compares the calculated difference amount with a predetermined threshold (S101). When the difference amount is larger than the threshold value, black is displayed in the subfield SFx2 as shown in FIG. 3A (S102). When the difference amount is smaller than the threshold value, black is displayed in the subfield SFx1 as shown in FIG. 3B (S103). When the difference amount is equal to the threshold value, the process may proceed to S102 or may proceed to S103. When the threshold is set to 0, every change between frames is handled for each pixel.

  Hereinafter, the black display control method of this embodiment will be described in detail. In this embodiment, the pixel groups 1 and 2 are arranged so that the composition ratio per unit area is substantially equal and without directivity. That is, the pixel groups 1 and 2 are arranged so that the appearance period of the pixels 1 and 2 does not change even if the entire region is rotated 90 degrees or inverted. By doing so, it is possible to reduce the direction dependency on the calculation result of the difference amount between frames. In this embodiment, as shown in FIG. 5, the pixels 1, 3, 6, 8, 9, 11, 14, 16 are set as a pixel group 1, and the pixels 2, 4, 5, 7, 10, 12, 13, 15 is a pixel group 2.

  Here, the black display control method will be described with reference to a diagram showing an image in which a rectangle is scrolled from left to right by one pixel per frame shown in FIG. 6A. A case where black display is performed in a conventional fixed field will be described with reference to FIG. In FIG. 14, in the subfield SFx1 or SFx2, black display is performed in the entire region. In this case, the subfields SFx1 and SFx2 are largely blinked, and the viewer feels flicker.

  FIG. 7 is a diagram illustrating execution of black display in each frame of the present embodiment. In the frame F2, the pixels 1, 3, 6, 8, 9, 11, 14, and 16 classified into the pixel group 1 are always displayed in black in the subfield SF22. Among the pixels 2, 4, 5, 7, 10, 12, 13, and 15 classified into the pixel group 2, the pixels 2, 4, 5, 7, 12, 13, and 15 that do not move from the frame F1 are The subfield SF21 is displayed in black. On the other hand, the pixel 10 that moves from the frame F1 is displayed in black in the subfield SF22. At this time, the luminance of the pixels 7, 8, 11, 12, 15, and 16 having no motion changes between the subfield SF <b> 21 and the subfield SF <b> 22. However, the average luminance does not change between the subfield SF21 and the subfield SF22 in a region continuous as a space including the pixels 7, 8, 11, 12, 15, and 16. Therefore, the viewer is less likely to feel flicker. In addition, the edge-like region including the moving pixels 6, 10, and 14 outputs the original luminance in the subfield SF21 and is displayed in black in the subfield SF22, so that the moving image blur is improved.

  According to the control method described above, moving image blur due to impulse driving is improved in a region with motion, and flicker is not visually observed by performing black display so that the luminance for each subfield is constant in a region without motion. In addition, when black display is performed for each pixel according to the difference amount between frames, it is necessary to perform luminance compensation and color compensation depending on whether black display is performed, but it is difficult to perform them from liquid crystal characteristics. However, in this embodiment, since black display is performed in all pixels, it is not necessary to perform luminance compensation and color compensation.

  The configuration of the liquid crystal projector of the present embodiment is the same as that of the liquid crystal projector of the first embodiment. In the present embodiment, similarly to the first embodiment, the pixel groups 1 and 2 are arranged so that the configuration ratio per unit area is substantially equal and without directivity. In this embodiment, as shown in FIG. 8, in the frames F1, F3, and F5, the pixels 1, 3, 6, 8, 9, 11, 14, and 16 are set as the pixel group 1, and the pixels 2, 4, 5, 7, 10, 12, 13, and 15 are defined as a pixel group 2. In the frames F2 and F4, the pixels 2, 4, 5, 7, 10, 12, 13, and 15 are the pixel group 1, and the pixels 1, 3, 6, 8, 9, 11, 14, and 16 are the pixel group 2. And

  Also in the present embodiment, a black display control method will be described with reference to a diagram showing an image in which a rectangle is scrolled from left to right by one pixel per frame shown in FIG. FIG. 9 is a diagram illustrating execution of black display in each frame of the present embodiment.

  In the frame F2, the pixels 2, 4, 5, 7, 10, 12, 13, and 15 classified into the pixel group 1 are always displayed in black in the subfield SF22. Among the pixels 1, 3, 6, 8, 9, 11, 14, and 16 classified into the pixel group 2, the pixels 1, 3, 8, 9, 11, and 16 that do not move from the frame F1 are subfields. Black is displayed at SF21. On the other hand, the moving pixels 6 and 14 from the frame F1 are displayed in black in the subfield SF22.

  In the frame F3, the pixels 1, 3, 6, 8, 9, 11, 14, and 16 classified into the pixel group 1 are always displayed in black in the subfield SF32. Among the pixels 2, 4, 5, 7, 10, 12, 13, and 15 classified into the pixel group 2, the pixels 2, 4, 10, and 12 that do not move from the frame F2 are displayed in black in the subfield SF31. Is done. On the other hand, the moving pixels 5, 7, 13, and 15 from the frame F2 are displayed in black in the subfield SF32.

  The luminance of the pixels 7, 8, 11, 12, 15, and 16 having no motion in the frame F2 changes between the subfield SF21 and the subfield SF22. However, the average luminance does not change between the subfield SF21 and the subfield SF22 in a region continuous as a space including the pixels 7, 8, 11, 12, 15, and 16. Therefore, the viewer is less likely to feel flicker. Similarly, the pixels 4, 8, 12, and 16 having no motion in the frame F3 change in luminance between the subfield SF31 and the subfield SF32. However, the average luminance does not change between the subfield SF31 and the subfield SF32 in a region that is continuous as a space including the pixels 4, 8, 12, and 16. Therefore, the viewer is less likely to feel flicker. Also, the moving edge-shaped region including the moving pixels 6, 10, and 14 in the frame F 2 outputs the original luminance in the subfield SF 21 and is displayed in black in the subfield SF 22, so that the moving image blur is generated. Improved. Similarly, the edge-like region including the moving pixels 5, 7, 9, 11, 13, and 15 in the frame F 3 outputs the original luminance in the subfield SF 31, and black display is performed in the subfield SF 32. , Video blur is improved.

  According to the control method described above, moving image blur due to impulse driving is improved in a region with motion, and flicker is not visually observed by performing black display so that the luminance for each subfield is constant in a region without motion. Further, when black display is performed for each pixel in accordance with the difference in frame feeling, it is necessary to perform luminance compensation and color compensation depending on whether or not black display is performed, but it is difficult to perform them from the liquid crystal characteristics. However, in this embodiment, since black display is performed in all pixels, it is not necessary to perform luminance compensation and color compensation.

  The configuration of the liquid crystal projector of the present embodiment is the same as that of the liquid crystal projectors of the first and second embodiments. In this embodiment, the pixel groups 1 and 2 are arranged so that the composition ratio per unit area is substantially equal. In this embodiment, as shown in FIG. 10A, the pixels 1, 2, 3, 4, 9, 10, 11, 12 are set as a pixel group 1, and the pixels 5, 6, 7, 8, 13, 14 are used. , 15 and 16 are set as a pixel group 2.

  Also in the present embodiment, a black display control method will be described with reference to a diagram showing an image in which a rectangle is scrolled from left to right by one pixel per frame shown in FIG. FIG. 11A is a diagram illustrating the execution of black display in each frame of the present embodiment.

  In the frame F2, the pixels 1, 2, 3, 4, 9, 10, 11, and 12 classified in the pixel group 1 are always displayed in black in the subfield SF22. Of the pixels 5, 6, 7, 8, 13, 14, 15, 16 classified into the pixel group 2, the pixels 5, 7, 8, 13, 15, 16 that do not move from the frame F1 are subfields. Black is displayed at SF21. On the other hand, the moving pixels 6 and 14 from the frame F1 are displayed in black in the subfield SF22. At this time, the luminance of the pixels 3, 4, 7, 8, 11, 12, 15, and 16 that do not move is changed between the subfield SF21 and the subfield SF22. However, the average luminance does not change between the subfield SF21 and the subfield SF22 in a continuous area as a space including the pixels 3, 4, 7, 8, 11, 12, 15, and 16. Therefore, the viewer is less likely to feel flicker. In addition, the edge-like region including the moving pixels 6, 10, and 14 outputs a target luminance in the subfield SF21 and performs black display in the subfield SF22, so that the moving image blur is improved.

  According to the control method described above, moving image blur due to impulse driving is improved in a region with motion, and flicker is not visually observed by performing black display so that the luminance for each subfield is constant in a region without motion. In addition, when black display is performed for each pixel according to the difference amount between frames, it is necessary to perform luminance compensation and color compensation depending on whether black display is performed, but it is difficult to perform them from liquid crystal characteristics. However, in this embodiment, since black display is performed in all pixels, it is not necessary to perform luminance compensation and color compensation.

  FIG. 12 is a block diagram of the liquid crystal projector of this embodiment. Unlike the other embodiments, the liquid crystal projector of this embodiment includes a motion detection circuit (determination means) 110. The motion detection circuit 110 determines which of the horizontal motion amount of the video (input image) of the input signal or the vertical motion amount orthogonal to the horizontal direction is greater. For example, a similar block of a plurality of consecutive frames of the input signal is searched, and if the block moves largely in the horizontal direction from the vertical direction, it is determined that the block moves in the horizontal direction, and if the block moves in the vertical direction from the horizontal direction, Judge that it is moving vertically. It is also possible to control the place of interest by dividing the region and using a weighted average value of the movement direction for each region. Since other configurations are the same as those of the other embodiments, detailed description thereof is omitted.

  In this embodiment, the pixel groups 1 and 2 are arranged so that the composition ratio per unit area is substantially equal. In this embodiment, pixel groups 1 and 2 are arranged for each frame as shown in FIGS. 10 (a) and 10 (b). The arrangement of FIG. 10A is used when it is determined that the input image is moving in the horizontal direction, and the pixels in the pixel groups 1 and 2 are adjacent in the horizontal direction and not adjacent in the vertical direction. The arrangement of FIG. 10B is used when it is determined that the input image is moving in the vertical direction, and the pixels of the pixel groups 1 and 2 are adjacent in the vertical direction and not adjacent in the horizontal direction.

  FIG. 13 is a flowchart illustrating a method for determining the arrangement of pixel groups in each frame, which is executed by the controller 107, based on the output from the motion detection circuit, and “S” is an abbreviation for a step. First, the motion detection circuit 110 determines whether the amount of motion in the horizontal direction or the vertical direction of the input image is larger (S201). If the motion detection circuit 110 determines that the amount of motion in the vertical direction is large, the controller 107 arranges the pixel group as shown in FIG. 10B (S202). If the motion detection circuit 110 determines that the amount of motion in the horizontal direction is large, the controller 107 arranges the pixel group as shown in FIG. 10A (S203). In this embodiment, the movement direction of the input image is determined for each frame, but the movement direction may be determined from more frames.

  Next, a black display control method according to this embodiment will be described. First, the case where the figure shown in FIG. 6A showing an image in which a rectangle is scrolled from left to right by one pixel per frame will be described.

  FIG. 14 shows a case where black display is performed in the entire region in the subfield SFx1 or SFx2. In this case, the subfields SFx1 and SFx2 are largely blinked, and the viewer feels flicker.

  FIG. 15 shows a case where a pixel group is arranged for the vertical movement in FIG. 10B and black display is performed in each frame, regardless of the detection result of the motion detection circuit 110. Since the pixel groups 1 and 2 are arranged along the vertical direction, pixels on which black display is performed continue over two subfields. For example, in the pixels 6, 10, and 14 in the edge directions of the frames F2 and F3, black display is continuously performed in the subfields SF22 and SF31, and the visibility is deteriorated.

  In this embodiment, the motion detection circuit 110 determines that the video in FIG. 6A has a larger amount of horizontal motion. If it is determined that the amount of movement in the horizontal direction is larger, the controller 107 arranges the pixel group for horizontal movement as shown in FIG. FIG. 11A is a diagram illustrating execution of black display in each frame in a state where the pixel group is arranged for horizontal movement.

  In the frame F2, the pixels 1, 2, 3, 4, 9, 10, 11, and 12 classified in the pixel group 1 are always displayed in black in the subfield SF22. Of the pixels 5, 6, 7, 8, 13, 14, 15, 16 classified into the pixel group 2, the pixels 5, 7, 8, 13, 15, 16 that do not move from the frame F1 are subfields. Black is displayed at SF21. On the other hand, the moving pixels 6 and 14 from the frame F1 are displayed in black in the subfield SF22. Therefore, pixels in which black display is continuously performed in the two subfields are not adjacent to each other.

  Next, a case will be described in which the figure shown in FIG. 6B shows an image in which a rectangle scrolls from top to bottom by one pixel per frame. In the present embodiment, the motion detection circuit 110 determines that the amount of motion in the vertical direction of the video in FIG. If it is determined that the amount of motion in the vertical direction is larger, the controller 107 arranges the pixel group for vertical motion as shown in FIG. FIG. 11B is a diagram showing execution of black display in each frame in a state where the pixel group is arranged for vertical movement.

In the frame F2, 1, 3, 5, 7, 9, 11, 13, and 15 classified into the pixel group 1 are always displayed in black in the subfield SF22. In addition, 2, 4, 6, 8, which are classified into the pixel group 2
Among pixels 10, 12, 14, and 16, pixels 2, 4, 10, 12, 14, and 16 that do not move from the frame F1 are displayed in black in the subfield SF21. On the other hand, the moving pixels 6 and 8 from the frame F1 are displayed in black in the subfield SF22. At this time, the luminance of the non-moving pixels 2, 4, 10, 12, 14, and 16 changes between the subfield SF21 and the subfield SF22. However, the average luminance does not change between the subfield SF21 and the subfield SF22 in a continuous region as a space including the pixels 2, 4, 10, 12, 14, and 16. Therefore, the viewer is less likely to feel flicker. In addition, since the edge-like region including the moving pixels 6, 7, and 8 outputs the target luminance in the subfield SF21 and is displayed in black in the subfield SF22, the motion blur is improved. Therefore, pixels in which black display is continuously performed in the two subfields are not adjacent to each other.

  According to the control method described above, the motion blur is improved by impulse driving in a region where there is motion, and flicker is not visually recognized by performing black display so that the luminance for each subfield is constant in a region where there is no motion. In addition, when black display is performed for each pixel according to the difference amount between frames, it is necessary to perform luminance compensation and color compensation depending on whether black display is performed, but it is difficult to perform them from liquid crystal characteristics. However, in this embodiment, since black display is performed in all pixels, it is not necessary to perform luminance compensation and color compensation.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

106 Liquid crystal panel 107 Controller (control means)

Claims (9)

A liquid crystal panel in which a plurality of pixels divided into a first pixel group and a second pixel group are arranged in a matrix;
Control means for dividing one frame into a first period and a subsequent second period and controlling the luminance of the plurality of pixels;
The first pixel group is controlled such that the luminance during the first period is greater than the luminance during the second period;
The second pixel group is controlled such that the luminance of the first period is greater than the luminance of the second period when a difference between corresponding pixels between frames is greater than a predetermined threshold. Is smaller than the predetermined threshold, the display device is controlled so that the luminance in the first period is smaller than the luminance in the second period. The pixels included in the first pixel group are arranged not to be adjacent to each other in a first direction and a second direction orthogonal to the first direction,
The display device according to claim 1, wherein pixels included in the second pixel group are arranged so as not to be adjacent to each other in the first and second directions.   The display device according to claim 1, wherein the first and second pixel groups are exchanged for each frame. A determination unit for determining a movement direction of the input image;
The display device according to claim 1, wherein the control unit changes an arrangement of the first and second pixel groups according to the determination of the determination unit.   In the first and second pixel groups, the pixels included in the first pixel group are adjacent to the pixels included in the second pixel group in the first direction, and are orthogonal to the first direction. The display device according to claim 4, wherein the display device is arranged so as not to be adjacent in the direction of 2. The movement directions are the first and second directions;
When the movement direction is the first direction, the control means includes a pixel included in the first pixel group adjacent to a pixel included in the second pixel group in the first direction, When the first and second pixel groups are arranged so as not to be adjacent in the two directions, and the movement direction is the second direction, the pixels included in the first pixel group are the second pixels. 6. The display according to claim 5, wherein the first and second pixel groups are arranged so as to be adjacent to pixels included in the group in the second direction and not adjacent to each other in the first direction. apparatus. A control method for a display device including a liquid crystal panel in which a plurality of pixels including a first pixel group and a second pixel group are arranged in a matrix,
Dividing one frame into a first period and a subsequent second period;
Comparing corresponding pixel differences between frames with a predetermined threshold;
When the difference between corresponding pixels between frames is larger than a predetermined threshold, the first pixel group is controlled such that the luminance in the first period is larger than the luminance in the second period, The pixel group is controlled such that the luminance during the first period is greater than the luminance during the second period;
When the difference is smaller than the predetermined threshold, the first pixel group is controlled such that the luminance of the first period is larger than the luminance of the second period, and the second pixel group is And a step of controlling the luminance of the first period to be smaller than the luminance of the second period.   The program which makes a computer perform the control method of Claim 7.   A storage medium for storing the program according to claim 8.