Display device

Abstract

To improve display quality in a multi-view display device compared with conventional ones.SOLUTION: In a display device (1P), a display panel (31) includes a first pixel group (313A) contributing to formation of a first image on a display surface (319) and a second pixel group (313B) contributing to formation of a second image. A barrier (316) prevents part of first light, which is illumination light emitted from a backlight (32P) and wavelength-converted by the first pixel group (313A), and part of second light, which is the illumination light wavelength-converted by the second pixel group (313B), from traveling toward the display surface (319). In a first display mode, the display device (1P) minimizes the light transmittance of the display panel (31) at positions corresponding to the second pixel group (313B) and stops emission of second illumination light having directivity toward a second position. In a second display mode, the display device (1P) minimizes the light transmittance of the display panel (31) at positions corresponding to the first pixel group (313A) and stops emission of first illumination light (90A) having directivity toward a first position.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The following disclosure relates to display devices. [Background technology]

[0002] A display device that can present multiple individual images corresponding to the viewing direction of a user (viewer) on a single display surface is called a multi-view display device. Patent Document 1 listed below discloses an example of the configuration of a multi-view display device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication WO2004 / 088996 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present disclosure is to improve the display quality of a multi-view display device compared to conventional devices. [Means for solving the problem]

[0005] In order to solve the above problem, a display device according to one aspect of the present disclosure is a display device that presents a first image to a first user located at a first position relative to a display surface, and presents a second image different from the first image to a second user located at a second position different from the first position, the display device including a display panel having a first pixel group that contributes to forming the first image on the display surface and a second pixel group that contributes to forming the second image on the display surface, a backlight that emits illumination light toward the first pixel group and the second pixel group, and a backlight that emits illumination light toward the display surface, the first pixel group being a portion of the illumination light whose wavelength has been converted by the first pixel group, and the second pixel group being a portion of the illumination light whose wavelength has been converted by the second pixel group. and a control unit that controls the display panel and the backlight, wherein in a first display mode, the control unit (i) controls the display panel to minimize the light transmittance of the display panel at a position corresponding to the second pixel group, and (ii) controls the backlight to stop emission of second illumination light, which is the illumination light having directionality toward the second position, and in a second display mode different from the first display mode, (i) controls the display panel to minimize the light transmittance of the display panel at a position corresponding to the first pixel group, and (ii) controls the backlight to stop emission of first illumination light, which is the illumination light having directionality toward the first position. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, it is possible to improve the display quality of a multi-view display device compared to conventional methods. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a display device according to a reference embodiment. [Figure 2] 1 illustrates a schematic diagram of a dual view display. [Figure 3] FIG. 1 is a schematic plan view illustrating a dual-view structure. [Figure 4]10A and 10B are diagrams for explaining various lights involved in dual view in an ideal operation example of the reference embodiment. [Figure 5] 10 shows examples of a first image and a second image displayed in an ideal operation example of the reference embodiment. [Figure 6] 10A and 10B are diagrams for explaining various lights involved in dual view in an actual operation example of the reference embodiment. [Figure 7] 10 shows examples of a first image and a second image displayed in an actual operation example of the reference embodiment. [Figure 8] 1 is a block diagram showing an example of the configuration of a display device according to a first embodiment. [Figure 9] 1A and 1B are diagrams for explaining various lights involved in dual view in the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of operation in a first period. [Figure 11] FIG. 10 is a diagram illustrating an example of operation in a second period. [Figure 12] 3A and 3B schematically illustrate a time sequence of display control of a first image and a second image in a first period and a second period. [Figure 13] FIG. 10 is a diagram illustrating an angle θ as an explanatory variable. [Figure 14] 1 shows an example of white luminance in the reference embodiment and the first embodiment. [Figure 15] 15 is a graph showing an enlarged portion of the graph in FIG. 14. [Figure 16] 1 shows an example of black luminance in the reference embodiment and the first embodiment. [Figure 17] 10 shows examples of crosstalk index values ​​in the reference embodiment and the first embodiment. [Figure 18] An example of the light directionality of BL is shown. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Reference form] Prior to describing the display device 1P of the first embodiment, a display device 1 as a reference embodiment will be described. For convenience of explanation, components having the same functions as those described in the reference embodiment will be denoted by the same reference numerals in the following embodiments, and their descriptions will not be repeated. Also, for brevity, descriptions of matters similar to those in known technologies will be omitted as appropriate. All components and numerical values ​​described in this specification are merely examples unless otherwise stated. Therefore, for example, unless otherwise stated, the positional and connection relationships of each component are not limited to the examples in the figures.

[0009] FIG. 1 is a block diagram showing an example of the configuration of a display device 1. The display device 1 includes a control unit 2 and a display unit 3. The display device 1 may be a mobile information terminal or a stationary display device. In this specification, "backlight" is abbreviated as "BL." In this specification, a case where the display device 1 is a liquid crystal display device is exemplified.

[0010] The control unit 2 comprehensively controls each component of the display device 1. In the reference embodiment, the control unit 2 functions as a display control device that controls the display of the display unit 3. The control unit 2 includes a panel control unit 21 and a BL control unit 22. Therefore, the control unit 2 controls the display panel 31 and the BL 32 described below.

[0011] The panel control unit 21 generates liquid crystal data corresponding to an arbitrary input image. The liquid crystal data is data that indicates the spatial distribution of the liquid crystal transmittance (light transmittance of the liquid crystal) in the display panel 31. The panel control unit 21 supplies the generated liquid crystal data to the panel drive unit 33, which will be described below.

[0012] The BL control unit 22 generates BL data corresponding to the input image. The BL data is data that indicates the spatial distribution of luminance in the BL 32. The BL control unit 22 supplies the generated BL data to a BL driving unit 34, which will be described below.

[0013] The display unit 3 displays the input image in accordance with instructions from the control unit 2. The display unit 3 in the first embodiment is a liquid crystal display. In the example of Fig. 1, the display unit 3 includes a display panel 31, a BL 32, a panel driving unit 33, and a BL driving unit 34.

[0014] The display panel 31 has a display area in which a plurality of pixels (more precisely, display pixels) PIX are arranged. In this specification, a liquid crystal display panel is exemplified as the display panel 31. The display panel 31 displays a predetermined image in accordance with instructions from the control unit 2.

[0015] For ease of explanation, this specification uses an XYZ Cartesian coordinate system as shown in FIG. 2 (described later). The X and Y directions correspond to the column and row directions of the display panel 31, respectively. The Z direction is the normal direction to the display surface of the display panel 31. In this specification, it is assumed that the user of the display device 1 is located on the positive side of the Z direction. For this reason, the positive side of the Z direction is also referred to as the viewer side. On the other hand, the negative side of the Z direction is also referred to as the substrate side. In this specification, the Z direction is also the thickness direction of the display device 1.

[0016] As is clear from the above description, the XY plane in this specification is a plane parallel to the display surface of the display panel 31. As shown in Fig. 1, the display panel 31 has a plurality of pixels PIX regularly arranged in each of the X and Y directions.

[0017] The BL32 has a light-emitting element (not shown) as a light source for the display unit 3. The BL32 may have one or more light-emitting elements. By controlling the light emission of the light-emitting element, the spatial distribution of brightness in the BL32 can be controlled. The BL32 emits illumination light toward the display unit 3. In this specification, a case where the light-emitting element is a white LED (Light Emitting Diode) is exemplified. Therefore, in this specification, a case where the illumination light is white light is exemplified.

[0018] The panel driving unit 33 drives the display panel 31 in accordance with the liquid crystal data acquired from the panel control unit 21. Specifically, the panel driving unit 33 changes the light transmittance at each position on the display panel 31 in accordance with the liquid crystal data.

[0019] The BL driving unit 34 drives the BL 32 in accordance with the BL data acquired from the BL control unit 22. Specifically, the BL driving unit 34 controls the lighting of the BL 32 in accordance with the BL data. More specifically, the BL driving unit 34 controls the brightness of the light-emitting elements in the BL 32 in accordance with the BL data.

[0020] As described above, the control unit 2 (i) drives the display panel 31 through the panel drive unit 33, and (ii) drives the BL 32 through the BL drive unit , thereby causing the display panel 31 to display an input image.

[0021] The display device 1 in the reference embodiment is a multi-view liquid crystal display device. For clarity of explanation, the reference embodiment illustrates a case where the display device 1 is a dual-view liquid crystal display device. Therefore, the display device 1 is configured to present two separate images (dual-view display) depending on the viewing direction of the user.

[0022] In this specification, one of the two separate images in a dual-view display is referred to as a first image, and the other is referred to as a second image. The display device 1 in the reference embodiment is an example of a known dual-view liquid crystal display device. In this specification, the second image is an image different from the first image.

[0023] Fig. 2 schematically illustrates dual view display on the display device 1. In Fig. 2, two users are illustrated as viewers of an image displayed on the display device 1. In this specification, one of the two users is referred to as a first user U1, and the other is referred to as a second user U2.

[0024] In the example of FIG. 2, the side facing the negative X direction is referred to as the first side, and the side facing the positive X direction is referred to as the second side. That is, the second side is the side opposite the first side in the X direction. In the example of FIG. 2, the first side is the left side in the plane of the paper. The first side may also be referred to as side A. Meanwhile, the second side is the right side in the plane of the paper. The second side may also be referred to as side B.

[0025] In this specification, it is assumed that a first user U1 is located at a first position relative to the display surface (not shown in FIG. 2) of the display device 1. Meanwhile, it is assumed that a second user U2 is located at a second position relative to the display surface. In this specification, it is assumed that the second position is a position different from the first position.

[0026] In the example of FIG. 2, the first user U1 is located on a first side of the display surface, and the second user U2 is located on a second side of the display surface. Therefore, in this specification, the second position is exemplified as a position opposite to the first position. In the example of FIG. 2, the first position is a position on the left side of the display surface of the display device 1, and the second position is a position on the right side of the display surface. In the example of FIG. 2, the first image 190A is an image presented to the first user U1. On the other hand, the second image 190B is an image presented to the second user U2.

[0027] 3 is a schematic plan view illustrating a dual-view structure (a hardware configuration for realizing a dual-view display device). In the reference embodiment, a case is illustrated in which the display panel 31 is an RGB (Red, Green, Blue) liquid crystal display panel. In the example of FIG. 3, one pixel PIX is composed of one red subpixel SUBPX_R, one green subpixel SUBPX_G, and one blue subpixel SUBPX_B.

[0028] In the example of FIG. 3, the red subpixel SUBPX_R has a red color filter, the green subpixel SUBPX_G has a green color filter, and the blue subpixel SUBPX_B has a blue color filter.

[0029] Therefore, the white light emitted from BL32 that enters the red subpixel SUBPX_R is converted to red light. The white light emitted from BL32 that enters the green subpixel SUBPX_G is converted to green light. The white light emitted from BL32 that enters the blue subpixel SUBPX_B is converted to blue light. In the display panel 31, an image is displayed on the display surface using the red, green, and blue lights that are emitted from the pixel PIX and proceed toward the viewing side.

[0030] As described above, the display device 1 is a dual-view liquid crystal display device. Therefore, the display panel 31 in the example of Fig. 3 has a first pixel group 313A and a second pixel group 313B. The first pixel group 313A is a group of pixels PIX that contribute to displaying a first image. On the other hand, the second pixel group 313B is a group of pixels PIX that contribute to displaying a second image.

[0031] The first pixel group 313A in the example of FIG. 3 is a group of pixels PIX with odd column numbers. Therefore, for example, the pixel PIX located in the first column belongs to the first pixel group 313A. The pixel PIX located in the third column also belongs to the first pixel group 313A. On the other hand, the second pixel group 313B in the example of FIG. 3 is a group of pixels PIX with even column numbers. Therefore, for example, the pixel PIX located in the second column belongs to the second pixel group 313B. The pixel PIX located in the fourth column also belongs to the second pixel group 313B.

[0032] As described above, the first pixel groups 313A and the second pixel groups 313B are alternately positioned along the X direction in the display panel 31. In this way, for example, when observed along the direction from the first position to the second position (e.g., the X direction), the first pixel groups 313A and the second pixel groups 313B can be alternately positioned in the display panel 31.

[0033] In addition, as shown in FIG. 3, the display panel 31 further includes a barrier 316. The barrier 316 may include any light-absorbing material. The barrier 316 may also be called a parallax barrier. The barrier 316 may also be called a light-blocking portion. When viewed from the display surface, the barrier 316 covers a portion of the first pixel group 313A and a portion of the second pixel group 313B (see also FIG. 4 described below). In other words, the barrier 316 is located closer to the viewer than the first pixel group 313A and the second pixel group 313B.

[0034] In this specification, the light obtained by wavelength conversion (e.g., color conversion) of the illumination light emitted from BL32 by the first pixel group 313A is referred to as the first light. On the other hand, the light obtained by wavelength conversion of the illumination light emitted from BL32 by the second pixel group 313B is referred to as the second light. The barrier 316 prevents a portion of the first light from traveling toward the display surface (not shown in FIG. 3) of the display panel 31. The barrier 316 also prevents a portion of the second light from traveling toward the display surface.

[0035] (Example of dual view in reference format) 4 and 5 show an ideal example of dual-view operation in the display device 1. FIG. 4 is a diagram for explaining various types of light involved in dual-view. As shown in FIG. 4, the display panel 31 is located closer to the viewer than the BL 32. In FIG. 4, in addition to the first pixel group 313A, the second pixel group 313B, and the barrier 316 described above, a display surface 319 is also shown as each component of the display panel 31.

[0036] As described above, the BL driving unit 34 drives the BL 32 in accordance with commands from the BL control unit 22. Therefore, as shown in Fig. 4, illumination light 80 is emitted from the BL 32 toward the first pixel group 313A and the second pixel group 313B. As shown in Fig. 4, the BL 32 in the reference embodiment does not have any particular optical directivity.

[0037] At the same time, panel driver 33 drives display panel 31 in accordance with instructions from panel controller 21. Specifically, panel driver 33 drives first pixel group 313A and second pixel group 313B in accordance with instructions from panel controller 21. In the example of Fig. 4, panel controller 21 drives first pixel group 313A and second pixel group 313B under the control of panel driver 33 so as to cause display panel 31 to display a first image and a second image.

[0038] In an ideal operating example, the light absorption rate of the barrier 316 is assumed to be 100%. Therefore, as shown in Fig. 4, an opening HL that allows a portion of the first light and a portion of the second light to pass through is formed in the barrier 316. The opening HL is positioned so as to expose a portion of each of the first pixel group 313A and the second pixel group 313B when viewed from the display surface.

[0039] Therefore, a portion of the first light having directivity toward the first side passes through the opening HL and heads toward the display surface 319A. Light 81A in FIG. 4 is an example of first light having directivity toward the first position that passes through the opening HL and heads toward the display surface 319. The light 81A has directivity toward the first side, for example. The light 81A contributes to the formation of a first image on the display surface 319.

[0040] On the other hand, a portion of the second light having directivity toward the second position passes through the opening HL and proceeds toward the display surface 319. Light 81B in FIG. 4 is an example of the second light having directivity toward the second side that passes through the opening HL and proceeds toward the display surface 319. Light 81A has directivity toward the second side, for example. Light 81B contributes to the formation of a second image on the display surface 319.

[0041] Fig. 5 shows examples of a first image and a second image displayed in an ideal operating example of the display device 1. Fig. 5 corresponds to the example of Fig. 4 described above. The first image 190A in Fig. 5 is an image showing a black background and a white circle located in the center. The second image 190B in Fig. 5 is an image showing a black and white checkered pattern.

[0042] 5 is an ideal example, and therefore no crosstalk occurs between the first image 190A and the second image 190B. In this specification, crosstalk refers to a phenomenon in which one display image is mixed with another display image in a multi-view display. In the following description of the reference embodiment, as an example of crosstalk, a case in which one display image is mixed with the other display image in a dual-view display will be described.

[0043] 6 and 7 show an actual operation example of the dual view in the display device 1. FIGS. 6 and 7 are counterparts of the above-described FIGS. 4 and 5, respectively. First, let us refer to FIG. 6. In this actual operation example, unlike the example of FIG. 4, the first light, which has directionality toward the second position, is not completely blocked by the barrier 316. For example, in this actual operation example, a portion of the first light passes through the opening HL toward the display surface 319. Light 82A in FIG. 6 is an example of the first light, which has directionality toward the second position, passing through the opening HL toward the display surface 319.

[0044] Similarly, in an actual operation example, the light of the second light that has directionality toward the first position is not completely blocked by the barrier 316. For example, in an actual operation example, a portion of the second light passes through the opening HL toward the display surface 319. Light 82B in FIG. 6 is an example of the second light that has directionality toward the first position and passes through the opening HL toward the display surface 319.

[0045] In addition, the light absorption rate of the actual barrier 316 is lower than 100%. Therefore, in an actual operation example, a portion of the first light passes through a portion of the barrier 316 that overlaps with the first pixel group 313A and the second pixel group 313B and proceeds toward the display surface 319. Similarly, a portion of the second light passes through this portion and proceeds toward the display surface 319. Light 83A in FIG. 6 is an example of the first light that passes through this portion and proceeds toward the display surface 319, and has directionality toward the second position. Light 83B is an example of the second light that passes through this portion and proceeds toward the display surface 319, and has directionality toward the first position.

[0046] FIG. 7 shows examples of the first and second images displayed in an actual operation example of the display device 1. As described above with reference to FIG. 6, in an actual operation example, a portion of the first light is deflected to the second position. Therefore, the second image 191B in the example of FIG. 7 is an image in which the first image 190A is mixed into the second image 190B in the example of FIG. 5. The mixing of the first image 190A into the second image 190B is caused by the light 82A and light 83A in the example of FIG. 6. Thus, the light 82A and light 83A are undesirable first light in dual-view display.

[0047] Similarly, in an actual operation example, a portion of the second light will find its way around to the first position. Therefore, first image 191A in the example of FIG. 7 is an image in which second image 190B is mixed into first image 190A in the example of FIG. 5. The mixing of second image 190B into first image 190A is caused by light 82B and light 83B in the example of FIG. 6. Thus, light 82B and light 83B are undesirable second light in dual-view display.

[0048] [Embodiment 1] As described above, in the conventional technology (e.g., display device 1), the display quality of the first and second images in dual view display may be degraded. In order to solve this problem in the conventional technology, the inventors of the present application (hereinafter abbreviated as "the inventors") have newly created a display device 1P of embodiment 1 that is different from conventional display devices.

[0049] Fig. 8 is a block diagram showing an example of the configuration of a display device 1P. Fig. 8 is a diagram paired with the above-mentioned Fig. 1. The display device 1P includes a control unit 2P and a display unit 3P. The control unit 2P includes a panel control unit 21P and a BL control unit 22P. The display unit 3P includes a BL32P instead of the BL32.

[0050] (Example of dual view in embodiment 1) 9 is a diagram for explaining various types of light involved in dual view in display device 1P. In consideration of correspondence with the above-mentioned FIG. 5, FIG. 9 illustrates a virtual display mode in which a first light is emitted from first pixel group 313A and a second light is emitted from second pixel group 313B during a certain period. Therefore, it should be noted that the display mode in the example of FIG. 9 is different from the first display mode and second display mode described below.

[0051] As shown in FIG. 9, BL32P has higher light directivity in a predetermined direction (e.g., X direction) than BL32. In this specification, illumination light having directivity toward a first position is referred to as first illumination light. On the other hand, illumination light having directivity toward a second position is referred to as second illumination light. FIG. 9 illustrates first illumination light 90A and second illumination light 90B. As an example, the first illumination light 90A has directivity toward the first side, and the second illumination light 90B has directivity toward the second side.

[0052] Light 91A in FIG. 9 is an example of a first light that passes through the opening HL and proceeds toward the display surface 319 and has directivity toward a first position. The light 91A originates from the first illumination light 90A. Therefore, the light 91A has a higher directivity toward the first position than the above-described light 81A. As an example, the light 91A has a higher directivity toward the first side than the above-described light 81A.

[0053] Light 91B in FIG. 9 is an example of second light that passes through the opening HL and travels toward the display surface 319 and has directivity toward a second position. The light 91B originates from the second illumination light 90B. The light 91B has higher directivity toward the second side than the above-described light 81B. As an example, the light 91B has higher directivity toward the second side than the above-described light 81B.

[0054] For these reasons, crosstalk can be reduced compared to conventional methods by using BL32P, which has high optical directivity in the X direction. BL32P can be any BL with any light-guiding mechanism. Examples of light-guiding mechanisms include prism-shaped light guides, viewing angle control films, and louvers. These light-guiding mechanisms can generate first illumination light 90A and second illumination light 90B.

[0055] Additionally, the display device 1P employs a display control method different from that of the prior art to further reduce crosstalk. Specifically, the control unit 2P switches the light-emitting state of the display unit 3P during (i) a first period in which the display unit 3P displays a first image and (ii) a second period in which the display unit 3P displays a second image. In the first embodiment, the first period and the second period are separate periods. That is, in the first embodiment, unlike the reference embodiment, the first image and the second image are displayed in a time-division manner.

[0056] 10 and 11 each show an example of dual view operation in display device 1P. Each of Fig. 10 and Fig. 11 is a pair of Fig. 9 described above. First, Fig. 10 will be referred to. Fig. 10 is a diagram for explaining an example of operation in the first period.

[0057] The control unit 2P drives the display unit 3P in a first display mode during the first period. The first display mode is a mode intended to cause the display unit 3P to display only a first image during the first period.

[0058] Specifically, in the first display mode, the BL control unit 22P controls the BL drive unit 34 to cause the BL 32P to emit only the first illumination light 90A. In other words, in the first display mode, the BL control unit 22P controls the BL drive unit 34 to cause the BL 32P to stop emitting the second illumination light 90B. Therefore, in the first display mode, the second illumination light 90B is not emitted from the BL 32P (see reference numeral 95B in FIG. 10).

[0059] Additionally, in the first display mode, the panel control unit 21P controls the panel driving unit 33 to cause the display panel 31 to display the first image only at positions corresponding to the first pixel group 313A. In other words, in the first display mode, the panel control unit 21P controls the panel driving unit 33 to cause the display panel 31 to display black at positions corresponding to the second pixel group 313B.

[0060] Specifically, in the first display mode, the panel control unit 21P controls the panel driving unit 33 to minimize the light transmittance of the display panel 31 at a position corresponding to the second pixel group 313B. In this specification, the minimum value of the light transmittance is ideally 0.

[0061] By driving BL32P and the display panel 31 as described above, in the first display mode, unlike the second display mode described below, light 91B is not emitted from the second pixel group 313B (see reference numeral 96B in FIG. 10).

[0062] Therefore, in the first display mode, leakage of the second light from the second pixel group 313B to the first position is significantly reduced compared to the conventional case. Therefore, in the first display mode, the degree of mixing of the second image into the first image is significantly reduced compared to the conventional case. Ideally, in the first display mode of the display device 1P, only the first light having directionality toward the first position passes through the opening HL and heads toward the display surface 319 (see light 91A in FIG. 10 ).

[0063] Next, reference will be made to FIG. 11. FIG. 11 is a diagram for explaining an example of operation in the second period. In the second period, the control unit 2P drives the display unit 3P in the second display mode. The second display mode is a mode intended to cause the display unit 3P to display only the second image in the second period. In this way, the second display mode is a display mode different from the first display mode.

[0064] Specifically, in the second display mode, the BL control unit 22P controls the BL drive unit 34 to cause the BL 32P to emit only the second illumination light 90B. In other words, in the second display mode, the BL control unit 22P controls the BL drive unit 34 to cause the BL 32P to stop emitting the first illumination light 90A. Therefore, in the second display mode, the first illumination light 90A is not emitted from the BL 32P (see reference numeral 95A in FIG. 11).

[0065] Additionally, in the second display mode, the panel control unit 21P controls the panel driving unit 33 to cause the display panel 31 to display the second image only at positions corresponding to the second pixel group 313B. In other words, in the second display mode, the panel control unit 21P controls the panel driving unit 33 to cause the display panel 31 to display black at positions corresponding to the first pixel group 313A.

[0066] Specifically, in the second display mode, the panel control unit 21P controls the panel driving unit 33 to minimize the light transmittance of the display panel 31 at a position corresponding to the first pixel group 313A.

[0067] By driving the BL 32P and the display panel 31 as described above, in the second display mode, unlike the first display mode described above, the light 91A is not emitted from the first pixel group 313A (see reference numeral 96A in FIG. 11).

[0068] Therefore, in the second display mode, leakage of the first light from the first pixel group 313A to the second position is significantly reduced compared to the conventional case. Therefore, in the second display mode, the degree of mixing of the first image into the second image is significantly reduced compared to the conventional case. Ideally, in the second display mode of the display device 1P, only the second light having directionality toward the second position passes through the opening HL and heads toward the display surface 319 (see light 91B in FIG. 11 ).

[0069] Fig. 12 schematically shows the time series of display control of the first image and the second image in the first period and the second period. In Fig. 12, reference numeral 1210 indicates the time series of display control of the first image, and reference numeral 1220 indicates the time series of display control of the second image. In Fig. 12, t represents time on the time axis. In this specification, a case where the duration of the first period is equal to the duration of the second period is exemplified.

[0070] 12 illustrates, for convenience of explanation, a case in which the panel driver 33 has two separate drivers. The panel driver 33 in the example of FIG. 12 has a first driver dedicated to display control of the first image and a second driver dedicated to display control of the second image. In this example, the first driver is not involved in driving the portion of the display panel 31 corresponding to the second pixel group 313B. Similarly, the second driver is not involved in driving the portion of the display panel 31 corresponding to the first pixel group 313A.

[0071] First, the example of reference numeral 1210 will be described. The example of reference numeral 1210 corresponds to an operation example of the first driver. As described above, during the first period, the BL 32P emits only the first illumination light 90A under the control of the BL control unit 22P. Then, during the first period, the first driver drives only a portion of the display panel 31 corresponding to the first pixel group 313A so as to display only the first image on the display panel 31. As a result, during the first period, only the first image can be presented to the first user U1 located at a first position relative to the display panel 31 (e.g., the first user U1 located on the first side relative to the display panel 31).

[0072] On the other hand, in the example of reference numeral 1210, during the second period, the first driver causes the portion of the display panel 31 corresponding to the first pixel group 313A to display black. Therefore, during the second period, the first driver does not drive any portion of the display panel 31.

[0073] Next, an example of the reference numeral 1220 will be described. The example of the reference numeral 1220 corresponds to an example of the operation of the second driver. As described above, during the second period, the BL 32P emits only the second illumination light 90B under the control of the BL control unit 22P. Then, during the second period, the second driver drives only a portion of the display panel 31 corresponding to the second pixel group 313B so as to display only the second image on the display panel 31. As a result, during the second period, only the second image can be presented to the second user U2 located at a second position relative to the display panel 31 (e.g., the second user U2 located on the second side relative to the display panel 31).

[0074] On the other hand, in the example of reference numeral 1220, during the first period, the second driver causes the portion of the display panel 31 corresponding to the second pixel group 313B to display black. Therefore, during the first period, the second driver does not drive any portion of the display panel 31.

[0075] 12, in the first embodiment, the first period and the second period are alternately repeated. Therefore, the control unit 2P controls the display unit 3P to alternately switch between the first display mode and the second display mode. As an example, the control unit 2P may switch between the first display mode and the second display mode at a predetermined frequency.

[0076] Preferably, the control unit 2P switches between the first display mode and the second display mode at a frequency of 120 Hz or higher. By switching between the first display mode and the second display mode at a frequency of 120 Hz or higher, flicker that may occur when switching between the first display mode and the second display mode becomes less noticeable to the user. This further improves the display quality of the dual view display in the first embodiment.

[0077] (Example of quantitative evaluation results) The inventors performed various quantitative evaluations of the display device 1 and the display device 1P to verify the effects of the display device 1P. As an example, consider a case where the first image is a white display image (an image showing only a white background) and the second image is a black display image (an image showing only a black background). In this case, the first image is mixed into the second image during dual view display, which can increase the luminance of the second image.

[0078] Therefore, for example, when the display state is changed from a predetermined display state to another display state, an index value indicating the degree of crosstalk (hereinafter referred to as a "crosstalk index value") can be determined based on the increase in luminance of the display panel. In the following description, crosstalk will also be abbreviated as XT.

[0079] In this example, the display state of the liquid crystal panel is represented as W for white display and K for black display. In this example, the state in which white display is made on the first side and black display is made on the second side is represented as "AWBK." This representation is sometimes used to represent the brightness of the display panel in this state.

[0080] On the other hand, the state in which black is displayed on the first side and white is displayed on the second side is expressed as "AKBW." This expression is sometimes also used to represent the brightness of the display panel in this state.

[0081] Furthermore, the state in which black is displayed on the first side and black is displayed on the second side is expressed as "AKBK." This expression is sometimes also used to represent the brightness of the display panel in this state.

[0082] On the other hand, the state in which both the first side and the second side are displayed in white is expressed as "AWBW." This expression is sometimes used to represent the brightness of the display panel in this state.

[0083] Additionally, in this example, notation is introduced to represent the light emission state of BL. The notation "_A" indicates that the state of emitting light only to the first pixel group is maintained. The notation "_B" indicates that the state of emitting light only to the second pixel group is maintained. On the other hand, the notation "_AB" indicates that the state of emitting light to both the first pixel group and the second pixel group is maintained. This state corresponds to the operation example in the reference embodiment.

[0084] The notation "_S" indicates that the light-emitting state of the BL is controlled to be switched as described in the first embodiment. The notation "_N" indicates a general BL that does not have any particular light directivity. In this example, in cases other than "_N," the BL is assumed to have the light directivity described in the first embodiment.

[0085] As described above, in the example of the first embodiment, the first display mode and the second display mode are switched at a predetermined frequency. The length of the first period and the length of the second period are set to be equal. Based on this, in this example, the luminance in the case of "_S" is set as follows: AWBK_S=(AWBK_A+AKBW_B) / 2 …(1-1) AKBW_S=(AKBW_B+AKBK_A) / 2 …(1-2) AKBK_S=(AKBK_A+AKBK_B) / 2 …(1-3) AWBW_S=(AWBW_A+AWBW_B) / 2 …(1-4) It is set forth as follows.

[0086] FIG. 13 is a diagram illustrating the angle θ as an explanatory variable in this example. θ represents the tilt angle in the X direction with respect to the Y axis. θ is a parameter corresponding to the line of sight of a user when the user is viewing the display surface. As shown in FIG. 13, in this specification, when the optical axis of interest is parallel to the Y axis, θ=0°. Therefore, when the optical axis of interest is optical axis 1310 in FIG. 13, θ=0°.

[0087] In this specification, when the direction of the optical axis of interest coincides with the negative direction of the X direction, θ=−90°. Therefore, when the optical axis of interest is optical axis 1320 in FIG. 13, θ<0°. In the example of FIG. 13, the first user U1 is located on the side where θ is negative. In FIG. 13, the side where θ is negative is written as “θ=−side.” In FIG. 13, “θ=−side” corresponds to the first side.

[0088] On the other hand, if the direction of the optical axis under consideration coincides with the positive direction of the X direction, then θ=90°. Therefore, if the optical axis under consideration is optical axis 1330 in FIG. 13, then θ>0°. In the example of FIG. 13, second user U2 is located on the side where θ is positive. In FIG. 13, the side where θ is positive is written as "θ=+ side." In FIG. 13, "θ=+ side" corresponds to the second side.

[0089] Fig. 14 shows an example of white luminance (luminance of the display image of a white display) in the reference embodiment and embodiment 1. In the graph of Fig. 14, the horizontal axis represents θ and the vertical axis represents luminance. The horizontal axis is in degrees and the vertical axis is in arbitrary units.

[0090] 14, the peak waveform of white luminance is sharper in the case of "_S" than in the case of "_N." This indicates that the method of embodiment 1 can effectively reduce light leakage during dual view display compared to conventional methods.

[0091] Fig. 15 is a graph obtained by enlarging a portion of the graph in Fig. 14. Specifically, Fig. 15 is a graph obtained by enlarging the graph in Fig. 14 at a position near the value 0 on the vertical axis.

[0092] Fig. 16 shows examples of black luminance (luminance when a black display image is displayed) in the reference embodiment and embodiment 1. As shown in Fig. 16, the minimum black luminance is smaller in the case of "_S" than in the case of "_N." This also shows that the technique of embodiment 1 can effectively reduce light leakage during dual view display compared to conventional techniques.

[0093] Next, the inventors calculated the crosstalk index value XTA on the first side and the crosstalk index value XTB on the second side in the reference embodiment as follows: XTA = (AKBW-AKBK) / AKBK … (2A) XTB = (AWBK-AKBK) / AKBK … (2B) were respectively defined as follows.

[0094] Furthermore, the inventors have defined the crosstalk index value XTA_S on the first side and the crosstalk index value XTB_S on the second side in the first embodiment as follows: XTA_S=(AKBW_S-AKBK_S) / AKBK_S …(3A) XTB_S=(AWBK_S-AKBK_S) / AKBK_S …(3B) were respectively defined as follows.

[0095] Fig. 17 shows examples of crosstalk index values ​​in the reference embodiment and embodiment 1. The legend "embodiment 1" in Fig. 17 indicates the crosstalk index value in embodiment 1. The legend "comparison example 1" indicates the crosstalk index value on the first side in the reference embodiment when a BL with "_N" is used. The legend "comparison example 2" indicates the crosstalk index value in the reference embodiment when a BL with optical directionality is used.

[0096] 17, the crosstalk index value at θ<0° represents the crosstalk index value on the first side. Specifically, the crosstalk index value on the first side in Comparative Examples 1 and 2 represents the above-mentioned XTA. On the other hand, the crosstalk index value on the first side in Embodiment 1 represents the above-mentioned XTA_S.

[0097] 17, the crosstalk index value at θ>0° represents the crosstalk index value on the second side. Specifically, the crosstalk index value on the second side in Comparative Examples 1 and 2 represents the above-mentioned XTB. On the other hand, the crosstalk index value on the second side in Embodiment 1 represents the above-mentioned XTB_S.

[0098] 17, the method of embodiment 1 can effectively reduce the crosstalk index value compared to the reference embodiment. This also shows that the method of embodiment 1 can effectively reduce light leakage during dual-view display compared to conventional methods. As described above, the quantitative evaluation results also support the idea that the method of embodiment 1 can improve the display quality of a multi-view display device compared to conventional methods.

[0099] (supplement) FIG. 18 shows an example of the light directivity of the BL in the quantitative evaluation described above. The legend "Embodiment 1: First Side" in FIG. 18 indicates the light directivity of the first side when the technique of Embodiment 1 is adopted. The legend "Embodiment 1: Second Side" indicates the light directivity of the second side when that technique is adopted. The legend "Comparative Example" indicates the light directivity of the "_N" BL. As can be seen from FIG. 18, each of the above-mentioned luminances in the display device is affected by the light directivity of the BL.

[0100] [Software implementation example] The functions of the display devices 1 to 1P (hereinafter referred to as "devices") can be realized by a program that causes a computer to function as the device, and a program that causes a computer to function as each control block of the device (particularly, each part included in the control units 2 to 2P).

[0101] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0102] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0103] In addition, some or all of the functions of each of the control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of one aspect of the present disclosure. In addition, the functions of each of the control blocks can also be realized by, for example, a quantum computer.

[0104] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0105] 〔summary〕 A display device according to a first aspect of the present disclosure is a display device that presents a first image to a first user located at a first position relative to a display surface, and presents a second image different from the first image to a second user located at a second position different from the first position, the display device comprising: a display panel having a first pixel group that contributes to forming the first image on the display surface and a second pixel group that contributes to forming the second image on the display surface; a backlight that emits illumination light toward the first pixel group and the second pixel group; and a backlight that prevents a portion of the first light, which is the illumination light whose wavelength has been converted by the first pixel group, and a portion of the second light, which is the illumination light whose wavelength has been converted by the second pixel group, from proceeding toward the display surface. The display device includes a barrier and a control unit that controls the display panel and the backlight, wherein in a first display mode, the control unit (i) controls the display panel to minimize the light transmittance of the display panel at a position corresponding to the second pixel group, and (ii) controls the backlight to stop emitting second illumination light, which is the illumination light having directionality toward the second position, and in a second display mode different from the first display mode, (i) controls the display panel to minimize the light transmittance of the display panel at a position corresponding to the first pixel group, and (ii) controls the backlight to stop emitting first illumination light, which is the illumination light having directionality toward the first position.

[0106] In a display device according to a second aspect of the present disclosure, in the first aspect, the control unit may alternately switch between the first display mode and the second display mode at a frequency of 120 Hz or higher.

[0107] In a display device according to a third aspect of the present disclosure, in the first or second aspect, the backlight may have a light guide mechanism that generates the first illumination light and the second illumination light.

[0108] In a display device according to aspect 4 of the present disclosure, in any one of aspects 1 to 3, an opening may be formed in the barrier, and in the first display mode, a portion of the first light having directionality toward the first position may pass through the opening toward the display surface, and in the second display mode, a portion of the second light having directionality toward the second position may pass through the opening toward the display surface.

[0109] In a display device according to aspect 5 of the present disclosure, in any one of aspects 1 to 4, the first pixel group and the second pixel group may be positioned alternately in the display panel when observed along a direction from the first position to the second position.

[0110] In a display device according to aspect 6 of the present disclosure, in any one of aspects 1 to 5, the first position may be a position on the left side of the display surface, and the second position may be a position on the right side of the display surface.

[0111] In the display device according to Aspect 7 of the present disclosure, in any one of Aspects 1 to 6, the display panel may be a liquid crystal display panel.

[0112] [Additional Notes] One aspect of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of one aspect of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0113] 1P display device 2P control unit 3P display 21P Panel control unit 22P BL control unit 31 Display panel 32P BL (backlight) 33 Panel drive unit 34 BL drive unit 90A First illumination light 90B 2nd illumination light 91A 1st Light 91B 2nd light 190A 1st image 190B 2nd image 313A 1st pixel group 313B 2nd pixel group 316 Barrier 319 Display surface HL aperture U1 First User U2 Second user

Claims

1. 1. A display device that presents a first image to a first user located at a first position relative to a display surface, and presents a second image different from the first image to a second user located at a second position different from the first position, a display panel having a first pixel group that contributes to forming the first image on the display surface and a second pixel group that contributes to forming the second image on the display surface; a backlight that emits illumination light toward the first pixel group and the second pixel group; a barrier that prevents a portion of first light, which is the illumination light whose wavelength has been converted by the first pixel group, and a portion of second light, which is the illumination light whose wavelength has been converted by the second pixel group, from traveling toward the display surface; a control unit that controls the display panel and the backlight, The control unit In a first display mode, (i) the display panel is controlled to minimize the light transmittance of the display panel at a position corresponding to the second pixel group, and (ii) the backlight is controlled to stop emitting the second illumination light, which is the illumination light having directionality toward the second position; In a second display mode different from the first display mode, (i) the display panel is controlled to minimize the light transmittance of the display panel at a position corresponding to the first pixel group, and (ii) the backlight is controlled to stop emitting first illumination light, which is the illumination light having directionality toward the first position.

2. The display device according to claim 1 , wherein the control unit alternately switches between the first display mode and the second display mode at a frequency of 120 Hz or higher.

3. The display device according to claim 1 , wherein the backlight includes a light guide mechanism that generates the first illumination light and the second illumination light.

4. The barrier has an opening formed therein, In the first display mode, a portion of the first light having directionality toward the first position passes through the opening and travels toward the display surface; The display device according to claim 1 , wherein in the second display mode, a portion of the second light having directionality toward the second position passes through the opening and travels toward the display surface.

5. 2. The display device according to claim 1, wherein the first pixel group and the second pixel group are alternately positioned on the display panel when observed along a direction from the first position to the second position.

6. the first position is a position on the left side of the display surface, The display device according to claim 1 , wherein the second position is a position on the right side of the display surface.

7. The display device according to claim 1 , wherein the display panel is a liquid crystal display panel.

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