Display device, light emitting device, light emission control method, and light emission control program

Abstract

A display device according to the present technology comprises a display panel, a first light source, a second light source, a third light source, a light guide unit, and a light source control unit. The display panel has a display surface and a light-incident surface, transmits light incident on the light-incident surface, and emits the light from the display surface. The light guide unit guides light incident from each of the first to third light sources, and causes the light to be incident on the light-incident surface, and the viewing angle characteristics of luminance on the display surface from the light emitted from each of the first to third light sources differ from one another. The light source control unit controls the light emission intensity of each of the first to third light sources on the basis of the luminance viewing angle contribution ratio per unit power consumption of each of the first to third light sources and a detected viewing angle, which is the viewing angle detected with respect to the display surface.

Description

Display device, light emitting device, light emission control method, and light emission control program

[0001] The present technology relates to a display device, a light-emitting device, a light-emission control method, and a light-emission control program that perform display by irradiating a display panel with light.

[0002] Some display devices, such as liquid crystal displays, use illumination light projected from a backlight onto a display panel to display images. The illumination light passes through the display panel and diffuses, and while light traveling in the direction of a user contributes to the user's visibility of the displayed image, illumination light traveling in the direction of no user does not contribute to the user's visibility of the displayed image and is therefore unnecessary light. Therefore, if this unnecessary light could be reduced, power consumption could be reduced.

[0003] For example, Patent Document 1 discloses an image display device that includes an illumination means that emits light beams in at least three directions in a time-division manner and a display element that displays an image illuminated by each light beam in a time-division manner, the illumination means emitting each light beam in the direction of each observer. Patent Document 2 discloses a light source control method that controls the lighting of a light source according to the position of an observer in a directional backlight that includes a waveguide and a light source array. Patent Document 3 further discloses a backlight unit that includes two prism sheets and is switchable between narrow directivity and polarized directivity.

[0004] Japanese Patent Application Laid-Open No. 2007-33633 Japanese Patent Application Laid-Open No. 2015-527597 Japanese Patent Application Laid-Open No. 2008-123925

[0005] However, the configuration described in Patent Document 1 assumes display in three specific directions and does not consider the light distribution between them. Furthermore, it does not clarify the light distribution control of the front light guide plate or the countermeasures against moire using the light output patterns of each light guide plate. Furthermore, the configuration described in Patent Document 2 controls individual light sources, which makes the control complex and costly, and the positions where light sources can be placed are limited, making it difficult to achieve high brightness and a large screen. Furthermore, it is difficult to uniform the brightness distribution when the light sources on both ends are turned on, and each light source is assigned a specific brightness viewing angle, so the light distribution between the light sources is not considered. The configuration described in Patent Document 3 does not allow the light sources to be driven and controlled according to the user's direction.

[0006] In view of the above circumstances, an object of the present technology is to provide a display device, a light-emitting device, a light-emission control method, and a light-emission control program that are capable of reducing power consumption.

[0007] To achieve the above object, a display device according to an embodiment of the present technology includes a display panel, a first light source, a second light source, a third light source, a light guiding unit, and a light source controller. The display panel has a display surface and a light incident surface opposite the display surface, and transmits light incident on the light incident surface and emits it from the display surface. The light guiding unit guides light incident from each of the first to third light sources to make it incident on the light incident surface, and the light emitted from the first to third light sources has mutually different luminance viewing angle characteristics on the display surface. The light source controller controls the emission intensities of each of the first to third light sources based on the luminance viewing angle contribution rates per unit power consumption of each of the first to third light sources and a detected viewing angle, where the luminance contribution rates of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle are defined as luminance viewing angle contribution rates.

[0008] The light source control unit may preferentially increase the emission intensity of a light source having a large contribution rate at the detected visible angle among the first to third light sources.

[0009] The light source control unit may increase the emission intensity of a light source having a large contribution rate at the detected visible angle among the first to third light sources, more than the emission intensity of a light source having a small contribution rate.

[0010] The light source control unit may control the emission intensities of the first to third light sources so that, when the viewing angle characteristic of the luminance on the display surface when the first to third light sources are simultaneously made to emit light at a specific emission intensity is set to a target characteristic, the luminance value when the display surface is viewed from the detected viewing angle matches the luminance value of the target characteristic.

[0011] The light source control unit may control the emission intensities of the first to third light sources so that, when a viewing angle characteristic of luminance on the display surface when the first to third light sources are simultaneously made to emit light at a specific emission intensity is set as a target characteristic, the luminance value when the display surface is viewed from a viewing angle within a viewing angle range that is an angle range that includes the detected viewing angle matches the luminance value of the target characteristic.

[0012] The light source control unit may be capable of switching between a first state in which the light emission intensities of the first to third light sources are controlled so that the luminance value when the display surface is viewed from a viewing angle within a first viewing angle range matches the luminance value of the target characteristic, and a second state in which the light emission intensities of the first to third light sources are controlled so that the luminance value when the display surface is viewed from a viewing angle within a second viewing angle range wider than the first viewing angle range matches the luminance value of the target characteristic.

[0013] The luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources may have a maximum value at a different specific viewing angle, and may gradually decrease as the viewing angle increases away from the specific viewing angle.

[0014] When two light sources among the first to third light sources whose maximum values ​​are close to each other are caused to emit light only between specific viewing angles where the respective maximum values ​​are reached, the light source control unit may increase the emission intensity of one light source and decrease the emission intensity of the other light source in accordance with the detected viewing angle.

[0015] When causing only the two light sources to emit light, the light source control unit may, when bringing the emission intensity of one of the two light sources closer to zero in accordance with the detected viewing angle, reduce the rate of change in emission intensity of the light source with the higher contribution rate of the two light sources and increase the rate of change in emission intensity of the light source with the lower contribution rate.

[0016] The light guide unit may be configured by stacking a first light guide plate that guides light incident from the first light source and makes it incident on the light incident surface, a second light guide plate that guides light incident from the second light source and makes it incident on the light incident surface, and a third light guide plate that guides light incident from the third light source and makes it incident on the light incident surface, wherein the first light guide plate has a first end face facing the first light source, a first front surface that is a main surface facing the display panel, and a first back surface that is a main surface opposite to the first front surface, the second light guide plate has a second end face facing the second light source, a second main surface that is a main surface facing the display panel, and a second back surface that is a main surface opposite to the second front surface, and the third light guide plate has a third end face facing the third light source, a third main surface that is a main surface facing the display panel, and a third back surface that is a main surface opposite to the third front surface.

[0017] The first light guide plate may be disposed farthest from the display panel among the first to third light guide plates, and light incident from the first end surface may be emitted from the first surface to the second rear surface; the second light guide plate may be disposed between the first light guide plate and the display panel, and light incident from the second end surface and light incident from the second rear surface may be emitted from the second surface to the third rear surface; and the third light guide plate may be disposed between the second light guide plate and the display panel, and light incident from the third end surface and light incident from the third rear surface may be emitted from the third surface to the light incident surface.

[0018] The light guide unit may further include a prism sheet disposed between the first light guide plate and the second light guide plate, and the prism sheet may have prisms with apexes abutting against the first surface.

[0019] The first light source may be a plurality of point light sources arranged along a horizontal direction, the second light source and the third light source may be a plurality of point light sources arranged along a vertical direction, and the second light source and the third light source may be located on opposite sides of the light guide unit.

[0020] The display device may further include a fourth light source and a fifth light source, wherein the light guide unit guides light incident from each of the first to fifth light sources to make it incident on the light incident surface, and the light emitted from each of the first to fifth light sources has a luminance viewing angle characteristic on the display surface that is different from one another, and the light source control unit may control the emission intensity of each of the first to fifth light sources based on a luminance viewing angle contribution rate per unit power consumption of each of the first to fifth light sources and a detected viewing angle that is a detected viewing angle relative to the display surface.

[0021] The first light source may be a plurality of point light sources arranged along a horizontal direction, the second to fifth light sources may be a plurality of point light sources arranged along a vertical direction, and the second light source and the fourth light source and the third light source and the fifth light source may be located on opposite sides of the light guide unit.

[0022] The first light source, the fourth light source, and the fifth light source may be a plurality of point light sources arranged along a horizontal direction, the second light source and the third light source may be a plurality of point light sources arranged along a vertical direction, and the first light source, the fourth light source, and the fifth light source may be located on opposite sides of the light-guiding unit.

[0023] The display device may further include a viewing angle detection unit that detects the detected viewing angle.

[0024] In order to achieve the object, a light emitting device according to one embodiment of the present technology includes: a first light source; a second light source; a third light source; a display surface; and a light guide unit that is disposed on the light incident surface side of a display panel having a light incident surface opposite to the display surface, and that transmits light incident on the light incident surface and causes light to exit from the display surface, and that guides the light incident from each of the first to third light sources to be incident on the light incident surface, and that has mutually different luminance viewing angle characteristics on the display surface of the light emitted from the first to third light sources; and a light source control unit that controls the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and based on a detected viewing angle that is a detected viewing angle for the display surface, where the luminance viewing angle contribution rate is a contribution rate of the luminance of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle.

[0025] In order to achieve the above object, one embodiment of the present technology provides a light emission control method for controlling light emission intensities of each of first to third light sources in a light emitting device including a first light source, a second light source, a third light source, and a light guiding unit, wherein the light guiding unit has a display surface and a light incident surface opposite to the display surface, and is disposed on the light incident surface side of a display panel that transmits light incident on the light incident surface and causes light to exit from the display surface, and guides the light incident from each of the first light source, the second light source, and the third light source to enter the light incident surface, and the light emitted from each of the first to third light sources has mutually different luminance viewing angle characteristics on the display surface, and where a luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance viewing angle contribution rate, the light emission intensity of each of the first to third light sources is controlled based on the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle that is a detected viewing angle for the display surface.

[0026] In order to achieve the above object, a light-emitting control program according to one embodiment of the present technology is a light-emitting control program that controls light emission intensities of each of first to third light sources in a light-emitting device including a first light source, a second light source, a third light source, and a light-guiding unit, wherein the light-guiding unit has a display surface and a light-incident surface opposite to the display surface, and is arranged on the light-incident surface side of a display panel that transmits light incident on the light-incident surface and causes light to exit from the display surface, and guides the light incident from each of the first light source, the second light source, and the third light source to enter the light-incident surface, and the light emitted from each of the first to third light sources has mutually different luminance-viewing-angle characteristics on the display surface, and where a luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance-viewing-angle contribution rate, the program operates an information processing device as a light source control unit that controls the light emission intensities of each of the first to third light sources based on the luminance-viewing-angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle that is a detected viewing angle with respect to the display surface.

[0027] 1 is a perspective view of a display device according to a first embodiment of the present technology; FIG. 2 is a front view of the display device; FIG. 3 is a left side view of the display device; FIG. 4 is a right side view of the display device; FIG. 5 is a bottom view of the display device; FIG. 6 is an exploded perspective view of a light guide unit included in the display device; FIG. 7 is a left side view of the light guide unit; FIG. 8 is a right side view of the light guide unit; FIG. 9 is a perspective view of a prism sheet included in the light guide unit; FIG. 10 is a schematic view showing an optical path of light emitted from a first light source in the light guide unit; FIG. 11 is a schematic view showing an optical path of light emitted from a second light source in the light guide unit; FIG. 12 is a schematic view showing an optical path of light emitted from a third light source in the light guide unit; FIG. 13 is a graph showing luminance-viewing angle characteristics on a display surface of the light guide unit; FIG. 14 is a graph showing luminance-viewing angle contribution rates per unit power consumption of a first light source, a second light source, and a third light source included in the display device; FIG. 15 is a graph showing lighting duty ratio settings used by a light source control unit included in the display device; FIG. 16 is a graph showing the luminance of each light source and the total luminance of three light sources in the display device; FIG. 17 is a schematic view showing operation of the light source control unit; 10 is a graph showing the luminance of each light source when the detected viewing angle is 60° left. FIG. 11 is a graph showing the luminance of each light source when the detected viewing angle is 45° left. FIG. 12 is a graph showing the luminance of each light source when the detected viewing angle is 30° left. FIG. 13 is a graph showing the luminance of each light source when the detected viewing angle is 5° left. FIG. 14 is a graph showing the luminance of each light source when the detected viewing angle is 0°. FIG. 15 is a graph showing the luminance of each light source when the detected viewing angle is 5° right. FIG. 16 is a graph showing the luminance of each light source when the detected viewing angle is 30° right. FIG. 17 is a graph showing the luminance of each light source when the detected viewing angle is 45° right. FIG. 18 is a graph showing the luminance of each light source when the detected viewing angle is 60° right. FIG. 19 is a graph showing the total power consumption of each light source in the display device. FIG. 20 is a graph showing a lighting duty ratio setting for wide range tracking used by a light source control unit included in the display device. FIG. 21 is a graph showing the luminance of each light source and the total luminance of three light sources and the viewing angle range in the display device. This is a graph showing the luminance of each light source when the detected viewing angle is 60° to the left, 45° to the left, and 30° to the left.10 is a graph showing the luminance of each light source when the detected viewing angle is 5° left. FIG. 11 is a graph showing the luminance of each light source when the detected viewing angle is 0°. FIG. 12 is a graph showing the luminance of each light source when the detected viewing angle is 5° right. FIG. 13 is a graph showing the luminance of each light source when the detected viewing angle is 30° right. FIG. 14 is a graph showing the luminance of each light source when the detected viewing angle is 45° right. FIG. 15 is a graph showing the luminance of each light source when the detected viewing angle is 60° right. FIG. 16 is a graph showing the total power consumption of each light source in the display device. FIG. 17 is a plan view of a display device having another configuration according to a first embodiment of the present technology. FIG. 18 is a graph showing the luminance-viewing angle characteristics on the display surface of the light guiding unit. FIG. 19 is a graph showing the luminance-viewing angle characteristics (target characteristics) on the display surface of the light guiding unit. FIG. 19 is a graph showing the luminance-viewing angle contribution rates per unit power consumption of a first light source, a second light source, and a third light source included in the display device. FIG. 19 is a graph showing lighting duty ratio settings used by a light source control unit included in the display device. FIG. 19 is a graph showing the luminance of each light source and the total luminance of three light sources in the display device. 10 is a graph showing the luminance of each light source when the detected viewing angle is 60° left. FIG. 11 is a graph showing the luminance of each light source when the detected viewing angle is 45° left. FIG. 12 is a graph showing the luminance of each light source when the detected viewing angle is 30° left. FIG. 13 is a graph showing the luminance of each light source when the detected viewing angle is 5° left. FIG. 14 is a graph showing the luminance of each light source when the detected viewing angle is 0°. FIG. 15 is a graph showing the luminance of each light source when the detected viewing angle is 5° right. FIG. 16 is a graph showing the luminance of each light source when the detected viewing angle is 30° right. FIG. 17 is a graph showing the luminance of each light source when the detected viewing angle is 45° right. FIG. 18 is a graph showing the luminance of each light source when the detected viewing angle is 60° right. FIG. 19 is a graph showing the total power consumption of each light source in the display device. FIG. 19 is a perspective view of a display device according to a second embodiment of the present technology. FIG. 19 is a right side view of the display device. FIG. 19 is a bottom view of the display device. FIG. 19 is a left side view of the light guide unit. FIG. 19 is a right side view of the light guide unit. 1 is a graph showing a luminance-viewing angle characteristic on a display surface of the light guide unit, a graph showing a luminance-viewing angle characteristic (target characteristic) on a display surface of the light guide unit, and a graph showing a luminance-viewing angle contribution rate per unit power consumption of a first light source, a second light source, and a third light source provided in the display device.10 is a graph showing a lighting duty ratio setting used by a light source control unit included in the display device. FIG. 11 is a graph showing the luminance of each light source and the total luminance of three light sources in the display device. FIG. 12 is a graph showing the luminance of each light source when the detected viewing angle is 60° to the left. FIG. 13 is a graph showing the luminance of each light source when the detected viewing angle is 45° to the left. FIG. 14 is a graph showing the luminance of each light source when the detected viewing angle is 30° to the left. FIG. 15 is a graph showing the luminance of each light source when the detected viewing angle is 5° to the left. FIG. 16 is a graph showing the luminance of each light source when the detected viewing angle is 0°. FIG. 17 is a graph showing the luminance of each light source when the detected viewing angle is 5° to the right. FIG. 18 is a graph showing the luminance of each light source when the detected viewing angle is 30° to the right. FIG. 19 is a graph showing the luminance of each light source when the detected viewing angle is 45° to the right. FIG. 19 is a graph showing the luminance of each light source when the detected viewing angle is 60° to the right. FIG. 19 is a graph showing the total power consumption of each light source in the display device. FIG. 10 is a plan view of a display device having another configuration according to a second embodiment of the present technology. Fig. 1 is a left side view of the display device; Fig. 2 is a right side view of the display device; Fig. 3 is a bottom view of the display device; Fig. 4 is a schematic diagram showing a hardware configuration of an information processing device that constitutes a control unit according to first and second embodiments of the present technology;

[0028] First Embodiment A display device according to a first embodiment of the present technology will be described.

[0029] [Configuration of Display Device] Fig. 1 is a schematic diagram of a display device 100 according to this embodiment. As shown in the figure, the display device 100 includes a display panel 110 and a light-emitting device 120. Figs. 2 to 5 are plan views of the display device 100 as viewed from different directions. For convenience, each component is shown separated in Figs. 3 to 5. In each of the figures of this embodiment, the X, Y, and Z directions are three directions that are orthogonal to each other, with the X direction being the horizontal direction and the Y direction being the vertical direction.

[0030] The display panel 110 displays an image using light (hereinafter, referred to as illumination light) incident from the light-emitting device 120. As shown in FIGS. 3 and 4 , the display panel 110 has a display surface 110a and a light incident surface 110b. The display surface 110a is the surface viewed by a user, and the light incident surface 110b is the surface opposite the display surface 110a. When illumination light from the light-emitting device 120 is incident on the light incident surface 110b, the illumination light passes through the display panel 110 and exits from the display surface 110a. At this time, an image formed on the display panel 110 is illuminated and displayed. The display panel 110 may be a liquid crystal panel for a television or digital signage, or may be any other display panel that displays an image using the illumination light. The shape and size of the display panel 110 are also not particularly limited.

[0031] The light-emitting device 120 irradiates illumination light onto the light incident surface 110b of the display panel 110. As shown in Fig. 1, the light-emitting device 120 includes a light guide unit 130, a first light source 141, a second light source 142, a third light source 143, and a control unit 150. Hereinafter, as shown in Fig. 2, the directions as viewed from the display surface 110a side will be referred to as the "right," "left," "top," and "bottom" of the display device 100.

[0032] The light guide unit 130 guides light incident from the first light source 141, the second light source 142, and the third light source 143, respectively, and causes the light to enter the light incident surface 110b. FIG. 6 is an exploded perspective view of the light guide unit 130, and FIGS. 7 and 8 are side views of the light guide unit 130. For convenience, FIGS. 7 and 8 also show the respective components separated from each other. As shown in these figures, the light guide unit 130 includes a first light guide plate 131, a second light guide plate 132, a third light guide plate 133, a reflective sheet 134, a prism sheet 135, and a diffusion sheet 136. These are stacked in the following order from the display panel 110 side: the diffusion sheet 136, the third light guide plate 133, the second light guide plate 132, the prism sheet 135, the first light guide plate 131, and the reflective sheet 134.

[0033] The first light guide plate 131 guides light incident from the first light source 141 and makes it incident on the light incident surface 110b. The first light guide plate 131 is made of a light-transmitting material and has an end surface 131a, a front surface 131b, and a back surface 131c, as shown in FIGS. 7 and 8 . The end surface 131a is the lower end surface of the first light guide plate 131 and faces the first light source 141. The front surface 131b is the main surface of the first light guide plate 131 that faces the display panel 110. The back surface 131c is the main surface of the first light guide plate 131 that is opposite to the front surface 131b. The first light guide plate 131 is a plate-like member whose thickness gradually decreases from the end surface 131a, and the back surface 131c is configured to be inclined with respect to the light incident surface 110b.

[0034] The second light guide plate 132 guides light incident from the second light source 142 and causes it to enter the light incident surface 110b. The second light guide plate 132 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern may be a fine dot pattern or a stepped prism pattern. As shown in FIG. 7 , the second light guide plate 132 has an end surface 132a, a front surface 132b, and a back surface 132c. The end surface 132a is the left end surface of the second light guide plate 132 and faces the second light source 142. The front surface 132b is the main surface of the second light guide plate 132 that faces the display panel 110. The back surface 132c is the main surface of the second light guide plate 132 opposite the front surface 132b.

[0035] The third light guide plate 133 guides light incident from the third light source 143 and causes it to enter the light incident surface 110b. The third light guide plate 133 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern may be a fine dot pattern or a stepped prism pattern. As shown in FIG. 8 , the third light guide plate 133 has an end surface 133a, a front surface 133b, and a back surface 133c. The end surface 133a is the right end surface of the end surfaces of the third light guide plate 133 and faces the third light source 143. The front surface 133b is the main surface of the third light guide plate 133 that faces the display panel 110. The back surface 133c is the main surface of the third light guide plate 133 opposite the front surface 133b.

[0036] The reflection sheet 134 is located on the rear surface 131c side of the first light guide plate 131, and the rear surface 131c side has light reflectivity. The reflection sheet 134 reflects the light emitted from the first light source 141 that is incident from the end surface 131a toward the front surface 131b. Furthermore, when light emitted from the second light source 142 and the third light source 143 is incident on the reflection sheet 134, the reflection sheet 134 also reflects the light toward the front surface 131b.

[0037] Prism sheet 135 diffuses light incident from first light guide plate 131. Fig. 9 is a perspective view of a portion of prism sheet 135 viewed from the first light guide plate 131 side. As shown in the figure, prism sheet 135 is provided with a large number of prisms, which are triangular prism-shaped convex portions extending in the left-right direction (X direction), and the apexes of the prisms abut against surface 131b of first light guide plate 131. This type of prism sheet is called a "reverse prism type."

[0038] The diffusion sheet 136 diffuses and transmits the light incident from the third light guide plate 133, allowing the light to be incident on the light incident surface 101b. The diffusion sheet 136 adjusts the light distribution and prevents the light distribution patterns of the light guide plates from being visible.

[0039] The first light source 141 causes light to enter the first light guide plate 131. The first light source 141 is disposed below the light guide unit 130 as shown in Fig. 2, and faces an end surface 131a of the first light guide plate 131 as shown in Figs. 3 and 4. The first light source 141 may be a plurality of point light sources arranged along the horizontal direction (X direction), and may be, for example, LEDs (Light Emitting Diodes).

[0040] The second light source 142 causes light to enter the second light guide plate 132. The second light source 142 is disposed to the left of the light guide unit 130 as shown in Fig. 2, and faces an end surface 132a of the second light guide plate 132 as shown in Fig. 5. The second light source 142 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0041] The third light source 143 causes light to enter the third light guide plate 133. The third light source 143 is disposed to the right of the light guide unit 130 as shown in Fig. 2, and faces an end surface 133a of the third light guide plate 133 as shown in Fig. 5. The third light source 143 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0042] The second light source 142 and the third light source 143 are located on opposite sides of the light guide unit 130, as shown in FIG. The first light source 141, the second light source 142, and the third light source 143 do not have to be the same light source, and may have different light emission intensities. The numbers of the first light source 141, the second light source 142, and the third light source 143 are not particularly limited, and may be different numbers. The second light source 142 and the third light source 143 have the same length of arranged sides, but may have different numbers.

[0043] The control unit 150 controls illumination light in the display device 100. The control unit 150 may be built into the display device 100, or may be mounted on another device connected to the display device 100. As shown in FIG. 1 , the control unit 150 includes a viewing angle detection unit 151 and a light source control unit 152.

[0044] The viewing angle detection unit 151 detects the viewing angle of the user with respect to the display surface 110a. The viewing angle θ is shown in FIG. 5. As shown in the figure, the viewing angle θ is the angle formed with respect to the normal N of the display surface 110a. The viewing angle detection unit 151 can detect the viewing angle θ based on the output of a line-of-sight detection sensor (not shown). Hereinafter, the viewing angle θ detected by the viewing angle detection unit 151 will be referred to as the "detected viewing angle θ". ｄ When the user facing the display surface 110a changes his / her posture or moves, the detected viewing angle θ ｄ When there are multiple users facing the display surface 110a, the viewing angle detection unit 151 detects the viewing angle θ of each user. ｄ The visual angle detection unit 151 detects the visual angle θ ｄ is supplied to the light source control unit 152.

[0045] The light source control unit 152 controls the light emission intensity of each of the first light source 141, the second light source 142, and the third light source 143. The light source control unit 152 can control the light emission intensity of each light source by adjusting the duty ratio (the ratio of the on time to the off time in pulse width modulation) of each light source. A specific control method by the light source control unit 152 will be described later.

[0046] The display device 100 has the above-described configuration. The display device 100 is not limited to a horizontally elongated rectangular shape with the horizontal direction (X direction) as the longitudinal direction and the vertical direction (Y direction) as the short side direction when viewed from the thickness direction (Z direction), as shown in FIG. 2 . The display device 100 may also be a square shape with equal lengths in the horizontal direction (X direction) and the vertical direction (Y direction) when viewed from the thickness direction (Z direction), or a vertically elongated rectangular shape with the horizontal direction (X direction) as the short side direction and the vertical direction (Y direction) as the long side direction. Furthermore, the display device 100 may be a circle, an ellipse, or any other shape when viewed from the thickness direction (Z direction).

[0047] [Regarding Illumination Light] The light emitted from each of the first light source 141, the second light source 142, and the third light source 143 will now be described. FIG. 10 is a schematic diagram showing the optical path of light emitted from the first light source 141. As indicated by the arrows in the figure, the light emitted from the first light source 141 enters the first light guide plate 131 from the end surface 131a, and is emitted from the surface 131b in a direction inclined relative to the Z direction (Y+ side = diagonally upward) due to a fine pattern or the like formed on the surface 131b or the back surface 131c. The light reaches the prism sheet 135, and its traveling direction is changed to the Z direction (front direction) by the prism sheet 135. The light then passes through the second light guide plate 132 and the third light guide plate 133, is further diffused by the diffusion sheet 136, and enters the light incident surface 101b.

[0048] 11 is a schematic diagram showing the optical path of light emitted from second light source 142. As indicated by the arrows in the figure, the light emitted from second light source 142 enters second light guide plate 132 from end surface 132a, is refracted and diffused by second light guide plate 132, and is emitted from surface 131b in a diagonal direction to the right. Subsequently, the light passes through third light guide plate 133, is further diffused by diffusion sheet 136, and enters light incident surface 101b.

[0049] 12 is a schematic diagram showing the optical path of light emitted from third light source 142. As indicated by the arrows in the figure, light emitted from third light source 143 enters third light guide plate 133 from end surface 133a, is refracted and diffused by third light guide plate 133, and is emitted from surface 131b in a diagonal left direction. Subsequently, the light is further diffused by diffusion sheet 136 and enters light incident surface 101b.

[0050] Looking at each light guide plate, light incident on the first light guide plate 131 from the end face 131a is emitted from the front face 131b to the back face 132c of the second light guide plate 132. Light incident on the second light guide plate 132 from the end face 132a and the back face 132c is emitted from the front face 132b to the back face 133c of the third light guide plate 133. Light incident on the third light guide plate 133 from the end face 133a and the back face 133c is emitted from the front face 133b to the light incident surface 101b.

[0051] In this way, the light emitted from each of the first light source 141, the second light source 142, and the third light source 143 is mixed and incident on the light incident surface 101b, becoming illumination light from the light incident surface 101b side toward the display panel 110.

[0052] As described above, the first light source 141 is disposed below the light guide unit 130, and the emitted light is refracted by the prism sheet 135. The diffusion sheet 136, the second light guide plate 132, and the third light guide plate 133 are disposed between the prism sheet 135 and the light incident surface 101b, which further diffuses the light. Therefore, a reverse prism type prism sheet 135 with very strong directionality is preferable.

[0053] On the other hand, the second light source 142 and the third light source 143 are arranged on both the left and right sides of the light guide unit 130, and the emitted light is refracted by the second light guide plate 132 and the third light guide plate 133. In order not to impede the directionality provided by the prism sheet 135, it is preferable not to use a prism pattern with a strong inclination and a high area ratio for the second light guide plate 132 and the third light guide plate 133.

[0054] With such a configuration of the light guide unit 130, the first light source 141, the second light source 142, and the third light source 143, the luminance viewing angle characteristics (hereinafter referred to as luminance viewing angle characteristics) on the display surface 110a are as follows. Fig. 13 is a graph showing the luminance viewing angle characteristics on the display surface 110a. In the figure, "First Light Source (Reference Duty Ratio)" indicates the luminance when the first light source 141 is caused to emit light at the reference duty ratio, "Second Light Source (Reference Duty Ratio)" indicates the luminance when the second light source 142 is caused to emit light at the reference duty ratio, and "Third Light Source (Reference Duty Ratio)" indicates the luminance when the third light source 143 is caused to emit light at the reference duty ratio. If the duty ratio when each light source is caused to emit light at the maximum emission intensity is 100%, the reference duty ratios for all of them are 50%.

[0055] As shown in the figure, the luminance of the "first light source (reference duty ratio)" is greatest from the front (viewing angle 0°) and decreases as the viewing angle increases left and right. The luminance of the "second light source (reference duty ratio)" is greatest to the right (viewing angle around +50°) and decreases as the viewing angle moves away from that angle. The luminance of the "third light source (reference duty ratio)" is greatest to the left (viewing angle around -50°) and decreases as the viewing angle moves away from that angle. Thus, the luminance-viewing angle characteristics of the light emitted from the first light source 141, the second light source 142, and the third light source 143 are different from one another. This difference is due to the configuration of the light guide unit 130 and the arrangement of each light source (see FIGS. 9 to 12 ).

[0056] FIG. 13 also shows the luminance of "all light sources simultaneously (reference duty ratio)." This shows the luminance when the first light source 141, the second light source 142, and the third light source 143 are simultaneously illuminated at the reference duty ratio, and corresponds to the sum of the luminance of each light source for each viewing angle. For example, the luminance (L Ａ　３０° ) are the luminance (L １　３０° ), the luminance of the second light source 142 (L ２　３０° ) and the luminance (L ３　３０°) is added together. As will be described later, the light source control unit 152 controls each light source so that the characteristics of "all light sources simultaneously (reference duty ratio)" are obtained and power consumption can be minimized. Therefore, hereinafter, the characteristics of "all light sources simultaneously (reference duty ratio)" are referred to as "target characteristics."

[0057] 14 is a graph showing the luminance viewing angle contribution ratio per unit power consumption of the first light source 141, the second light source 142, and the third light source 143. The "luminance viewing angle contribution ratio" is the contribution ratio of the luminance of each of the first light source 141, the second light source 142, and the third light source 143 to the luminance when the display surface 101a is viewed from each viewing angle. For example, in FIG. 13, when the viewing angle is +30°, the luminance (L Ａ　３０° ) with respect to the luminance (L １　３０° ) contributes the most, and the luminance (L ３　３０° ) has the smallest contribution.

[0058] The luminance viewing angle contribution rate per unit power consumption can be calculated from the luminance viewing angle characteristics and power consumption of each light source using the following (Equation 1) to (Equation 3).

[0059] R １θ = (L １θ / P １ ) / (L １θ / P １ +L ２θ / P ２ +L ３θ / P ３ ) (Formula 1) R ２θ = (L ２θ / P ２ ) / (L １θ / P １ +L ２θ / P ２ +L ３θ / P ３ ) (Formula 2) R ３θ = (L ３θ / P ３ ) / (L １θ / P １ +L ２θ / P ２ +L ３θ / P ３ ) (Formula 3)

[0060] In addition, the values ​​in (Equation 1) to (Equation 3) are as follows: L １θ : Luminance L as seen from a viewing angle θ when the first light source 141 is turned on at a reference duty ratio ２θ : Luminance L as seen from the viewing angle θ when the second light source 142 is turned on at the reference duty ratio ３θ P: luminance as seen from the viewing angle θ when the third light source 143 is turned on at the reference duty ratio １ P: Power consumption when the first light source 141 is turned on at the reference duty ratio ２ P: Power consumption when the second light source 142 is turned on at the reference duty ratio ３ R: Power consumption when the third light source 143 is turned on at the reference duty ratio １θ R: Brightness viewing angle contribution rate per unit power consumption at the viewing angle θ of the first light source 141 ２θ R: luminance viewing angle contribution rate per unit power consumption at the viewing angle θ of the second light source 142 ３θ : Brightness viewing angle contribution rate per unit power consumption at the viewing angle θ of the third light source 143

[0061] 14, the luminance-viewing-angle contribution ratio per unit power consumption has a maximum value at a different specific viewing angle θ. In the same figure, the maximum value of the luminance-viewing-angle contribution ratio per unit power consumption of the first light source 141 is denoted by M １ and the maximum value of the second light source 142 is represented as the maximum value M ２ , the same maximum value of the third light source 142 is the maximum value M ３ The maximum value M １ The visual angle θ is 0°, and the maximum value M ２ The visual angle θ is 48°, and the maximum value M ３ The viewing angle θ at which this occurs is −52°. The luminance viewing angle contribution rate per unit power consumption of each light source gradually decreases as the viewing angle θ at which this occurs becomes the maximum value.

[0062] Note that the magnitude relationship between the luminance of each light source at a specific viewing angle θ does not necessarily coincide with the magnitude relationship between the luminance-viewing angle contribution rate per unit power consumption. In the example shown in FIGS. 13 and 14 , the number of first light sources 141 is twice as many as that of second light sources 142 and third light sources 143, and the first light sources 141 also consume more power when turned on at the reference duty ratio. For this reason, even if the luminance of the first light source 141 is high at a specific viewing angle θ, the luminance-viewing angle contribution rate per unit power consumption at the same viewing angle θ may be smaller than that of the other light sources. For example, when the viewing angle θ is +30°, the luminance (L １　３０° ) is the largest (see FIG. 13), but the luminance viewing angle contribution rate per unit power consumption is the value of the second light source 142 (R ２　３０° ) is the largest.

[0063] As described above, the first light source 141 is arranged horizontally (X direction) below the light-guiding unit 130, and the second light source 142 and the third light source 143 are arranged vertically (Y direction) across the left and right sides of the light-guiding unit 130. This arrangement of the light sources is preferable. Light emitted from the first light source 141 passes through the prism sheet 135, but when the light is diffused vertically (Y direction) by the prism sheet 135, asymmetry tends to occur in the luminance viewing angle characteristics. Even if asymmetry occurs in the luminance viewing angle characteristics in the vertical direction (Y direction), the difference in luminance is less noticeable to the user because the amount of viewpoint movement in the vertical direction (Y direction) is smaller than in the horizontal direction (Y direction). If the second light source 142 or the third light source 143 were arranged farthest from the display panel 110, asymmetry in the luminance viewing angle characteristics in the horizontal direction (Y direction) would occur when the emitted light passes through the prism sheet 135, which could be noticeable to the user.

[0064] [Operation of Display Device] The operation of the display device 100 according to the embodiment of the present technology will be described. The light source control unit 152 calculates the luminance viewing angle contribution rate per unit power consumption of each of the first light source 141, the second light source 142, and the third light source 143, and the detected viewing angle θ ｄ The light emission intensity of each light source is controlled based on the detected viewing angle θ ｄ is the viewing angle θ detected by the viewing angle detection unit 151 as described above.

[0065] Specifically, the light source control unit 152 can control the light emission intensity of each light source using a "lighting duty ratio setting." Fig. 15 is a graph showing the lighting duty ratio setting. This lighting duty ratio setting is specified so that the target characteristics (see Fig. 13) described above are obtained according to the viewing angle θ, and the total power consumption of the first light source 141, the second light source 142, and the third light source 143 is minimized based on the luminance-viewing angle contribution rate per unit power consumption (see Fig. 14).

[0066] The light source control unit 152 determines the detected visible angle θ according to the lighting duty ratio setting. ｄ The light emission intensity of each light source is controlled so that the luminance value when the display surface 101a is viewed from the viewing angle θ coincides with the luminance value of the target characteristic (see FIG. 13). ｄ 16 is a graph showing the luminance of each light source and the total luminance of the three light sources when the detected viewing angle θ ｄ The luminance (L １　３０° ), the luminance (L ２　３０° ) and the luminance (L ３　３０° ) indicates the detection visibility angle θ ｄ is +30°, that is, the luminance (L Ｖ　３０° ) is the luminance (L １　３０° ), the luminance of the second light source 142 (L ２　３０° ) and the luminance (L ３　３０° ) (in the figure, "total of three light sources"), and the target characteristic luminance (L Ａ　３０° , see FIG. 13).

[0067] At this time, the light source control unit 152 determines the detected visible angle θ of the first light source 141, the second light source 142, and the third light source 143 according to the lighting duty ratio setting. ｄ In FIG. 15 , the light source control unit 152 increases the light emission intensity of the light source having a large contribution rate to the luminance per unit power consumption relative to the viewing angle. The light source control unit 152 can increase the light emission intensity of the light source having a large contribution rate relative to the viewing angle relative to the luminance per unit power consumption relative to the viewing angle ... １　３０°The duty ratio of the second light source 142 at the same viewing angle θ is represented as Duty ratio D ３　３０°、 The duty ratio of the third light source 143 at the same viewing angle θ is defined as duty ratio D ３　３０° Shown as:

[0068] As shown in FIG. 14, when the viewing angle θ is +30°, the light source control unit 152 determines that the luminance viewing angle contribution rate per unit power consumption is the value of the second light source 142 (R ２　３０° ), the value of one light source 141 (R １　３０° ), the value of the third light source 143 (R ３　３０° ), the duty ratio of each light source also decreases in the order of the value of the second light source 142 (D ２　３０° ), the value of one light source 141 (D １　３０° ), the value of the third light source 143 (D ３　３０° ) in that order. Similarly, for other viewing angles θ, the light source control unit 152 increases the emission intensity of light sources with a large luminance-viewing-angle contribution rate per unit power consumption compared to light sources with a small contribution rate. Note that the light source control unit 152 does not necessarily have to match the magnitude relationship between the Duts of the light sources with the magnitude relationship between the luminance-viewing-angle contribution rates per unit power consumption over the entire range of viewing angles θ, as long as it preferentially increases the emission intensity of light sources with a large luminance-viewing-angle contribution rate per unit power consumption.

[0069] The detected visual angle θ ｄ When the light source control unit 152 detects the viewing angle θ, the light source control unit 152 adjusts the light emission intensity of each light source according to the lighting duty ratio setting. Specifically, when two light sources among the first light source 141, the second light source 142, and the third light source 143 have close maximum values ​​of the luminance viewing angle contribution rate per unit power consumption, and the light source control unit 152 controls the light emission intensity of each light source according to the lighting duty ratio setting, the light source control unit 152 detects the viewing angle θ when the two light sources are caused to emit light within a specific viewing angle θ at which the two light sources have close maximum values ​​of the luminance viewing angle contribution rate per unit power consumption. ｄ 17 is a schematic diagram showing this operation. In the figure, the viewing angle θ is the viewing angle at which the luminance viewing angle contribution rate per unit power consumption of the first light source 141 becomes maximum. １ , the viewing angle of the second light source 142 is defined as a viewing angle θ ２ , the viewing angle of the third light source 143 is defined as a viewing angle θ ３Let's say.

[0070] The light source control unit 152 detects the visible angle θ ｄ is the viewing angle θ １ and the viewing angle θ ２ When only the first light source 141 and the second light source 142 are illuminated, the detection visibility angle θ ｄ becomes larger (arrow A1 in the figure), the light emission intensity of the first light source 141 is reduced and the light emission intensity of the second light source 142 is increased in accordance with the lighting duty ratio setting. ｄ becomes smaller (arrow A2 in the figure), the light emission intensity of the first light source 141 is increased and the light emission intensity of the second light source 142 is decreased in accordance with the lighting duty ratio setting.

[0071] Furthermore, the light source control unit 152 determines the detected visible angle θ ｄ is the viewing angle θ １ and the viewing angle θ ３ When only the first light source 141 and the third light source 143 are illuminated, the detection visibility angle θ ｄ becomes larger (arrow A3 in the figure), the light emission intensity of the first light source 141 is increased and the light emission intensity of the third light source 143 is decreased in accordance with the lighting duty ratio setting. ｄ becomes smaller (arrow A4 in the figure), the light emission intensity of the first light source 141 is reduced and the light emission intensity of the third light source 143 is increased in accordance with the lighting duty ratio setting.

[0072] Furthermore, when only two light sources having close maximum values ​​emit light, the light source control unit 152 determines the detected visible angle θ ｄ When one of the light sources approaches zero in accordance with the above, the light source with the higher luminance / viewing angle contribution rate per unit power consumption is made smaller in the light emission intensity change rate, and the light source with the lower luminance / viewing angle contribution rate is made larger. The light emission intensity change rate depends on the slope of the lighting duty ratio setting of each light source (in the figure, ΔD １ , ΔD ２ and ΔD ３ ) applies.

[0073] Specifically, the light source control unit 152 detects the visible angle θ ｄ is the viewing angle θ １ and the viewing angle θ ２When only the first light source 141 and the second light source 142 are illuminated, the detection visibility angle θ ｄ When the light emission intensity of the first light source 141 is brought close to zero (arrow B1 in the figure) in accordance with the lighting duty ratio setting, the light emission intensity change rate (ΔD ２ ) is reduced, and the light emission intensity change rate (ΔD １ ) to increase the size.

[0074] The light source control unit 152 also controls the visible output angle θ ｄ Even when the light emission intensity of the second light source 142 is brought closer to zero (arrow B2 in the figure) in accordance with the lighting duty ratio setting, the light emission intensity change rate (ΔD １ ) is reduced, and the emission intensity change rate (ΔD ２ ) to increase the size.

[0075] Similarly, the light source control unit 152 detects the visible angle θ ｄ is the viewing angle θ １ and the viewing angle θ ３ When only the first light source 141 and the third light source 143 are illuminated, the detection visibility angle θ ｄ When the light emission intensity of the first light source 141 is made to approach zero (arrow B3 in the drawing) in accordance with the lighting duty ratio setting, the light emission intensity change rate (ΔD ３ ) is reduced, and the light emission intensity change rate (ΔD １ ) to increase the size.

[0076] The light source control unit 152 also controls the visible output angle θ ｄ Even when the light emission intensity of the third light source 143 is brought closer to zero (arrow B4 in the figure) in accordance with the lighting duty ratio setting, the light emission intensity change rate (ΔD １ ) is reduced, and the light emission intensity change rate (ΔD ３ ) to increase the size.

[0077] As described above, the light source control unit 152 determines the detected visible angle θｄ The light source control unit 152 can control the light emission intensity of each light source so that the luminance value when the display surface 101a is viewed from the detected viewing angle θ matches the luminance value of the target characteristic. ｄ It is also possible to control the light emission intensity of each light source so that the luminance value when the display surface 101a is viewed from a viewing angle within an angle range including the above-mentioned angle matches the luminance value of the target characteristic.

[0078] 18 is a graph showing the angle range and the luminance of each light source. ｄ is supplied, the detected visual angle θ ｄ The visual angle range H is set to include the detected visual angle θ ｄ Any angle range including the detection visibility angle θ ｄ The range of the detected viewing angle θ is ±5°. The light source control unit 152 can control the light emission intensity of each light source so that the luminance value when the display surface 101a is viewed from a viewing angle within the viewing angle range H matches the luminance value of the target characteristic. Specifically, the light source control unit 152 controls the light emission intensity of each light source so that the luminance value when the display surface 101a is viewed from a viewing angle within the viewing angle range H matches the luminance value of the target characteristic. ｄ Furthermore, in the viewing angle range H, the light emission intensity of each light source is controlled so that the luminance value of the "target characteristic" matches the luminance value of the "total of three light sources."

[0079] The user's line of sight is detected by the visual angle θ due to changes in the user's posture, etc. ｄ If the detection visibility angle θ ｄ There is a risk that a time lag will occur between the redetection of the light source and the change in brightness of each light source, which may cause fluctuations in the brightness perceived by the user. In response to this, by providing a viewing angle range H, it is possible to prevent fluctuations in brightness even if the user's viewing angle θ moves within the viewing angle range H.

[0080] The light source control unit 152 detects the visible angle θ ｄ The light emission intensity of each light source may be controlled using a lighting duty ratio setting in which the luminance value of the "target characteristic" and the luminance value of the "total of three light sources" match only within the visible angle range H, or the light emission intensity of each light source may be controlled using a lighting duty ratio setting in which the luminance value of the "target characteristic" and the luminance value of the "total of three light sources" match within the visible angle range H.ｄ When there is almost no change in the detected visual angle θ ｄ The lighting duty ratio setting is used so that the brightness value matches only when the detection visibility angle θ ｄ If the detected visible angle θ fluctuates slightly, a lighting duty ratio setting that matches the luminance value within the visible angle range H can be used. ｄ If the fluctuation is large, it is also possible to use a lighting duty ratio setting for wide range tracking, which will be described later.

[0081] Hereinafter, the detected visible angle θ by the light source control unit 152 ｄ 19 to 27 are graphs showing the luminance of each light source at each viewing angle.

[0082] As shown in FIG. 19, the detected viewing angle θ ｄ is 60° to the left (-60°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 0%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 83.4% based on the lighting duty ratio setting. As a result, the light emitted only from the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from 60° to the left can view illumination light equivalent to that when all light sources are turned on at the standard duty ratio.

[0083] Furthermore, since the first light source 141 and the second light source 142 are not turned on at this time, the total power consumption can be reduced. Fig. 28 is a graph showing the total power consumption of each light source when the duty ratio of each light source is controlled in accordance with the lighting duty ratio setting (see Fig. 15). In this graph, the power consumption when all light sources are turned on at the reference duty ratio is set to 100%. As shown in this graph, the detected visual angle θ ｄ When the angle is 60° to the left, the same brightness can be achieved with about 40% of the power consumption compared to when all the light sources are turned on at the standard duty ratio.

[0084] As shown in FIG. 20, the detected visual angle θ ｄis 45° to the left (-45°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 29.5%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 73.2% based on the lighting duty ratio settings. As a result, the light emitted from the first light source 141 and the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from 45° to the left can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0085] As shown in FIG. 21, the detected viewing angle θ ｄ is 30° to the left (-30°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 54.2%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 64.8% based on the lighting duty ratio settings. As a result, the light emitted from the first light source 141 and the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from 30° to the left can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0086] As shown in FIG. 22, the detected visual angle θ ｄ is 5° left (-5°), the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 57.4%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 37.3% based on the lighting duty ratio settings. As a result, the light emitted from the first light source 141 and the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from 5° to the left can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0087] As shown in FIG. 23, the detected viewing angle θ ｄ is the front (0°), the visible angle range H is the detected visible angle θ ｄWhen the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 60.8%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 0% based on the lighting duty ratio setting. As a result, the light emitted only from the first light source 141 matches the target characteristics, and therefore a user viewing the display surface 101a from the front can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0088] As shown in FIG. 24, the detected viewing angle θ ｄ is 5° to the right (+5°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 55.6%, the duty ratio of the second light source 142 to 42.4%, and the duty ratio of the third light source 143 to 0% based on the lighting duty ratio setting. As a result, the light emitted from the first light source 141 and the second light source 142 matches the target characteristics, and therefore a user viewing the display surface 101a from 5° to the right can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0089] As shown in FIG. 25, the detected viewing angle θ ｄ is 30° to the right (+30°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 53.6%, the duty ratio of the second light source 142 to 60.3%, and the duty ratio of the third light source 143 to 0% based on the lighting duty ratio setting. As a result, the light emitted from the first light source 141 and the second light source 142 matches the target characteristics, and therefore a user viewing the display surface 101a from 30° to the right can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0090] As shown in FIG. 26, the detected viewing angle θ ｄ is 45° to the right (+45°), and the visual recognition angle range H is the detected visual recognition angle θ ｄWhen the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 21.6%, the duty ratio of the second light source 142 to 77.5%, and the duty ratio of the third light source 143 to 0% based on the lighting duty ratio setting. As a result, the light emitted from the first light source 141 and the second light source 142 matches the target characteristics, and therefore a user viewing the display surface 101a from 45° to the right can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0091] As shown in FIG. 27, the detected viewing angle θ ｄ is 60° to the right (+60°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 0%, the duty ratio of the second light source 142 to 87.7%, and the duty ratio of the third light source 143 to 0% based on the lighting duty ratio setting. As a result, the light emitted only from the second light source 142 matches the target characteristics, and therefore a user viewing the display surface 101a from 60° to the right can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0092] Detection visibility angle θ ｄ is the above-mentioned each detection visual angle θ ｄ Even when the visual angle θ is between θ 1 and θ 2 , the light source control unit 152 determines the duty ratio of each light source according to the lighting duty ratio setting (see FIG. 15 ). ｄ When the viewing angle θ fluctuates, the light source control unit 152 seamlessly changes the duty ratio in accordance with the lighting duty ratio setting. As shown in FIG. 27 , the total power consumption of the first light source 141, the second light source 142, and the third light source 143 is less than 100% at any viewing angle θ, making it possible to reduce power consumption.

[0093] [Regarding Wide-Range Tracking] The light source control unit 152 can use a lighting duty ratio setting for wide-range tracking when multiple users view the display surface 101a, or when a single user views the display surface 101a but the viewing angle changes significantly. Figure 29 is a graph showing lighting duty ratio settings for wide-range tracking. This lighting duty ratio setting is also specified so that the target characteristics (see Figure 13) described above are obtained according to the viewing angle θ, and the total power consumption of the first light source 141, the second light source 142, and the third light source 143 is minimized based on the luminance-viewing-angle contribution rate per unit power consumption (see Figure 14).

[0094] The light source control unit 152 determines the detected visible angle θ according to the lighting duty ratio setting. ｄ The light emission intensity of each light source is controlled so that the luminance value when the display surface 101a is viewed from a viewing angle range H including the detected viewing angle θ ｄ is +30°, and the visual angle range H is the detected visual angle θ ｄ 10 is a graph showing the luminance of each light source at an angle of ±20°. Ｖ　３０° ) is the luminance (L １　３０° ), the luminance of the second light source 142 (L ２　３０° ) and the luminance (L ３　３０° ) and the target characteristic luminance (L Ａ　３０° 13). The luminance perceived by the user when viewing the display surface 101a from an angle within the viewing angle range H also matches the luminance of the target characteristic (see FIG. 13).

[0095] In this way, the lighting duty ratio setting for wide range tracking is set so that the luminance perceived by the user matches the luminance of the target characteristic over the entire wide viewing angle range H. The light source control unit 152 controls the light emission intensity of each light source in accordance with this lighting duty ratio setting for range tracking so that the luminance value when the display surface 101a is viewed from a viewing angle θ within the viewing angle range H matches the luminance value of the target characteristic (see FIG. 13 ). The viewing angle range H is set within the range of the detected viewing angle θ ｄ The angle is not limited to ±20° and can be changed depending on the size of the display surface 101a, etc.

[0096] The light source control unit 152 holds the lighting duty ratio setting for narrow range tracking shown in FIG. 15 and the lighting duty ratio setting for wide range tracking shown in FIG. 16, and determines the detected viewing angle θ ｄ The light source control unit 152 can select which lighting duty ratio setting to use depending on, for example, the detected visible angle θ ｄ If there is one, a setting for narrow range tracking can be selected, and if there are multiple, a setting for wide range tracking can be selected. ｄ It is also possible to select a narrow range tracking setting if the moving speed is slow, and a wide range tracking setting if the moving speed is fast. The light source control unit 152 can use three or more lighting duty ratio settings with different widths of the visible angle range H.

[0097] Hereinafter, an example of control of the lighting duty ratio of each light source by the light source control unit 152 using the lighting duty ratio setting for wide range tracking will be described. ｄ 10 is a graph showing the luminance of each light source in FIG.

[0098] As shown in FIG. 31, the detected viewing angle θ ｄ is 60° to the left (-60°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the viewing angle range is ±20°, the light source control unit 152 sets the duty ratio of the first light source 141 to 49.1%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 65.4% based on the lighting duty ratio settings. As a result, the light emitted from the first light source 141 and the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from the viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0099] Furthermore, since the second light source 142 is not turned on at this time, the total power consumption can be reduced. Fig. 40 is a graph showing the total power consumption of each light source when the duty ratio of each light source is controlled in accordance with the lighting duty ratio setting for wide range tracking (see Fig. 29). In this graph, the power consumption when all light sources are turned on at the reference duty ratio is set to 100%. As shown in this graph, the detected visual angle θ ｄ When the angle is 60° to the left, the same brightness can be achieved with about 60% of the power consumption compared to when all the light sources are turned on at the standard duty ratio.

[0100] Other detection visibility angles θ ｄ 32 to 39 , the light source control unit 152 controls each light source so that a user viewing the display surface 101a from within the viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio. As shown in Fig. 39 , the total power consumption of the first light source 141, the second light source 142, and the third light source 143 is less than 100% at any viewing angle θ, making it possible to reduce power consumption.

[0101] [Another Configuration of the Display Device] Another configuration of the display device 100 will be described. Fig. 41 is a plan view of the display device 100 having another configuration. As shown in the figure, in this display device, the number of second light sources 142 and the number of third light sources 143 are different, and the light distribution characteristics are different on the left and right. In addition, a DBEF (Dual Brightness Enhancement Film) (not shown) is attached to the display panel 110, which changes the light distribution characteristics.

[0102] 42 and 43 are graphs showing the luminance-viewing-angle characteristics on the display surface 110a. As shown in FIG. 42, if the duty ratios of the light sources are all set to 50%, the left-right balance of luminance is lost. For this reason, as shown in FIG. 43, the duty ratio of the first light source 141 is set to 50%, the duty of the second light source 142 is set to 52%, and the duty of the third light source 142 is set to 20%, which are used as the reference duty ratios of each light source. The luminance characteristics at this time are referred to as "target characteristics." Note that the target characteristics may have a difference in luminance between the left and right, and the reference duty ratio may also be set to a value that achieves the target characteristics.

[0103] 44 is a graph showing the luminance-viewing angle contribution ratio per unit power consumption of the first light source 141, the second light source 142, and the third light source 143. The luminance-viewing angle contribution ratio per unit power consumption can be calculated using the above-mentioned (Equation 1) to (Equation 3). As shown in the figure, the luminance-viewing angle contribution ratio per unit power consumption has a maximum value at a different specific viewing angle θ. In the figure, the maximum value of the luminance-viewing angle contribution ratio per unit power consumption of the first light source 141 is shown as the maximum value M １ and the maximum value of the second light source 142 is represented as the maximum value M ２ , the same maximum value of the third light source 142 is the maximum value M ３ The maximum value M １ The visual angle θ is 0°, and the maximum value M ２ The visual angle θ is 48°, and the maximum value M ３ The viewing angle θ at which this occurs is −52°. The luminance viewing angle contribution rate per unit power consumption of each light source gradually decreases as the viewing angle θ at which this occurs becomes the maximum value.

[0104] 45 is a graph showing the lighting duty ratio setting for the display device 100. The light source control unit 152 determines the detected visible angle θ in accordance with the lighting duty ratio setting. ｄ The light emission intensity of each light source is controlled so that the luminance value when the display surface 101a is viewed from the outside coincides with the luminance value of the target characteristic (see FIG. 43).

[0105] FIG. 46 shows the detected viewing angle θ ｄ 1 is a graph showing the luminance of each light source when the angle of the light source is +30°. Ｖ　３０° ) is the luminance (L １　３０° ), the luminance of the second light source 142 (L ２　３０° ) and the luminance (L ３　３０° ) and corresponds to the luminance of the target characteristic (see FIG. 43).

[0106] Hereinafter, the detected visible angle θ by the light source control unit 152 ｄ 47 to 55 are graphs showing the luminance of each light source at each viewing angle.

[0107] As shown in FIG. 47, the detected viewing angle θ ｄ is 60° to the left (-60°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ If the angle is ±5°, the light source control unit 152 sets the duty ratio of the first light source 141 to 0%, the duty ratio of the second light source 142 to 0%, and the duty ratio of the third light source 143 to 57.5% based on the lighting duty ratio setting. As a result, the light emitted from the third light source 143 matches the target characteristics, and therefore a user viewing the display surface 101a from the viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0108] Furthermore, since the first light source 141 and the second light source 142 are not turned on at this time, the total power consumption can be reduced. Fig. 56 is a graph showing the total power consumption of each light source when the duty ratio of each light source is controlled in accordance with the lighting duty ratio setting for wide range tracking (see Fig. 45). In this graph, the power consumption when all light sources are turned on at the reference duty ratio is set to 100%. As shown in this graph, the power consumption when the detected visual angle θ ｄ When the angle is 60° to the left, the same brightness can be achieved with about 60% of the power consumption compared to when all the light sources are turned on at the standard duty ratio.

[0109] Other detection visibility angles θ ｄ 48 to 55, the light source control unit 152 controls each light source so that a user viewing the display surface 101a from within the viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio. As shown in Fig. 56, the total power consumption of the first light source 141, the second light source 142, and the third light source 143 is less than 100% at any viewing angle θ, making it possible to reduce power consumption.

[0110] As described above, the luminance viewing angle characteristics of each light source on the display surface 110a change depending on the configuration of the display device 100, such as the number of light sources and light distribution characteristics. However, the light source control unit 152 can reduce power consumption while maintaining the luminance perceived by the user by using a lighting duty ratio setting based on the luminance viewing angle contribution rate per unit power consumption.

[0111] In this embodiment, the light source control unit 152 controls the light emission intensity of each light source using the duty ratio, but it is also possible to control the light emission intensity of each light source by adjusting something other than the duty ratio, such as the current value.

[0112] Second Embodiment A display device according to a second embodiment of the present technology will be described. The display device according to this embodiment differs from the display device according to the first embodiment mainly in the number of light sources and light guide plates.

[0113] 57 to 60 are plan views of a display device 200 according to a second embodiment of the present technology, viewed from various directions. As shown in these figures, the display device 200 includes a display panel 210 and a light-emitting device 220. Note that, for convenience, each component is shown separated from the others in FIGS. 58 to 60.

[0114] The display panel 210 displays an image using illumination light incident from the light-emitting device 220. As shown in FIGS. 58 and 59 , the display panel 210 has a display surface 210a and a light incident surface 210b. The display surface 210a is the surface viewed by a user, and the light incident surface 210b is the surface opposite the display surface 210a. When illumination light from the light-emitting device 220 is incident on the light incident surface 210b, the display panel 210 transmits the illumination light and emits it from the display surface 210a. At this time, an image formed on the display panel 210 is illuminated and displayed. The display panel 210 may be a liquid crystal panel for a television or digital signage, or may be any other display panel that displays an image using the illumination light. The shape and size of the display panel 210 are also not particularly limited.

[0115] The light-emitting device 220 irradiates illumination light onto the light incident surface 210b of the display panel 210. As shown in Figures 58 and 59, the light-emitting device 220 includes a light guide unit 230, a first light source 241, a second light source 242, a third light source 243, a fourth light source 244, a fifth light source 245, and a control unit 250. Hereinafter, as shown in Figure 57, the directions as viewed from the display surface 210a side will be referred to as the "right," "left," "top," and "bottom" of the display device 200.

[0116] The light guide unit 230 guides the light incident from each of the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245, and causes the light to be incident on the light incident surface 210b. FIGS. 61 and 62 are side views of the light guide unit 230. For convenience, the components are also shown separated from one another in FIGS. 61 and 62 . As shown in these figures, the light guide unit 230 includes a first light guide plate 231, a second light guide plate 232, a third light guide plate 233, a fourth light guide plate 234, a fifth light guide plate 235, a reflective sheet 236, a prism sheet 237, and a diffusion sheet 238. These are stacked in the following order from the display panel 210 side: diffusion sheet 238, fifth light guide plate 235, fourth light guide plate 234, third light guide plate 233, second light guide plate 232, prism sheet 237, first light guide plate 231, and reflection sheet 236.

[0117] The first light guide plate 231 guides light incident from the first light source 241 and makes it incident on the light incident surface 210b. The first light guide plate 231 is made of a light-transmitting material and, as shown in FIG. 61 , has an end surface 231a, a front surface 231b, and a back surface 231c. The end surface 231a is the lower end surface of the end surfaces of the first light guide plate 231 and faces the first light source 241. The front surface 231b is the main surface of the first light guide plate 231 that faces the display panel 210. The back surface 231c is the main surface of the first light guide plate 131 that is opposite to the front surface 231z. The first light guide plate 131 is a plate-like member whose thickness gradually decreases from the end surface 131a, and the back surface 231c is configured to be inclined with respect to the light incident surface 210b.

[0118] The second light guide plate 232 guides light incident from the second light source 242 and causes it to enter the light incident surface 210b. The second light guide plate 232 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern can be a fine dot pattern or a stepped prism pattern. The pattern characteristics (scattering property / tilt angle) of the second light guide plate 232 are adjusted so that the viewing angle is approximately 50°. As shown in FIG. 61 , the second light guide plate 232 has an end surface 232a, a front surface 232b, and a back surface 232c. The end surface 232a is the left end surface of the second light guide plate 232 and faces the second light source 242. The front surface 232b is the main surface of the second light guide plate 232 that faces the display panel 210. The back surface 232c is the main surface of the second light guide plate 232 opposite the front surface 232b.

[0119] The third light guide plate 233 guides light incident from the third light source 243 and causes it to enter the light incident surface 210b. The third light guide plate 233 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern can be a fine dot pattern or a stepped prism pattern. The pattern characteristics (scattering property / tilt angle) of the third light guide plate 233 are adjusted so that the viewing angle is approximately 50°. As shown in FIG. 62 , the third light guide plate 233 has an end surface 233a, a front surface 233b, and a back surface 233c. The end surface 233a is the right end surface of the end surfaces of the third light guide plate 233 and faces the third light source 243. The front surface 233b is the main surface of the third light guide plate 233 that faces the display panel 210. The back surface 233c is the main surface of the third light guide plate 233 opposite the front surface 233b.

[0120] The fourth light guide plate 234 guides light incident from the fourth light source 244 and causes it to enter the light incident surface 210b. The fourth light guide plate 234 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern may be a fine dot pattern or a stepped prism pattern. The fourth light guide plate 234 has light distribution characteristics different from those of the second light guide plate 232, and the pattern characteristics (scattering property / inclination angle) are adjusted to provide a viewing angle of approximately 20°. As shown in FIG. 61 , the fourth light guide plate 234 has an end surface 234a, a front surface 234b, and a back surface 234c. The end surface 234a is the left end surface of the fourth light guide plate 234 and faces the fourth light source 244. The front surface 234b is the main surface of the fourth light guide plate 234 that faces the display panel 210. The rear surface 234c is one of the main surfaces of the fourth light guide plate 234 opposite to the front surface 234b.

[0121] The fifth light guide plate 235 guides light incident from the fifth light source 245 and causes it to enter the light incident surface 210b. The fifth light guide plate 235 is made of a light-transmitting material and is a flat plate-like member provided with a light distribution pattern (not shown). The light distribution pattern may be a fine dot pattern or a stepped prism pattern. The fifth light guide plate 235 has light distribution characteristics different from those of the third light guide plate 233, and the pattern characteristics (scattering property / inclination angle) are adjusted to provide a viewing angle of approximately 20°. As shown in FIG. 62 , the fifth light guide plate 235 has an end surface 235a, a front surface 235b, and a back surface 235c. The end surface 235a is the right end surface of the fifth light guide plate 235 and faces the fifth light source 245. The front surface 235b is the main surface of the fifth light guide plate 235 that faces the display panel 210. The rear surface 235c is one of the main surfaces of the fifth light guide plate 235 opposite to the front surface 235b.

[0122] The reflection sheet 236 is located on the rear surface 231c side of the first light guide plate 231, and the rear surface 231c side has light reflectivity. The reflection sheet 236 reflects the light emitted from the first light source 241 that is incident from the end surface 231a toward the front surface 231b side. Furthermore, when light emitted from other light sources is incident on the reflection sheet 134, the reflection sheet 236 also reflects that light toward the front surface 231b side.

[0123] Prism sheet 237 changes the traveling direction of light incident from first light guide plate 231 to the Z direction (front direction). Prism sheet 237 is a reverse prism type prism sheet (see FIG. 8 ), and can be structured so that the apexes of the prisms abut on surface 231 b of first light guide plate 231.

[0124] The diffusion sheet 238 diffuses and transmits the light incident from the fifth light guide plate 235, allowing the light to be incident on the light incident surface 210b. The diffusion sheet 238 adjusts the light distribution and prevents the light distribution patterns of each light guide plate from being visible.

[0125] The first light source 241 causes light to enter the first light guide plate 231. The first light source 241 is disposed below the light guide unit 230 as shown in Fig. 57 and faces the end surface 231a of the first light guide plate 231 as shown in Fig. 58 and 59. The first light source 241 may be a plurality of point light sources arranged along the horizontal direction (X direction), and may be, for example, LEDs.

[0126] The second light source 242 causes light to enter the second light guide plate 232. The second light source 242 is disposed to the left of the light guide unit 230 as shown in Fig. 57 and faces the end surface 232a of the second light guide plate 232 as shown in Fig. 58. The second light source 242 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0127] The third light source 243 causes light to enter the third light guide plate 233. The third light source 243 is disposed to the right of the light guide unit 230 as shown in Fig. 57 and faces the end surface 233a of the third light guide plate 233 as shown in Fig. 59. The third light source 243 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0128] The fourth light source 244 causes light to enter the fourth light guide plate 234. The fourth light source 244 is disposed to the left of the light guide unit 230 as shown in Fig. 57 and faces the end surface 234a of the fourth light guide plate 234 as shown in Fig. 58. The fourth light source 244 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0129] The fifth light source 245 causes light to enter the fifth light guide plate 235. The fifth light source 245 is disposed to the right of the light guide unit 230 as shown in Fig. 57 and faces the end surface 235a of the fifth light guide plate 235 as shown in Fig. 59. The fifth light source 245 may be a plurality of point light sources arranged along the vertical direction (Y direction), and may be, for example, LEDs.

[0130] As shown in FIG. 57 , the second light source 242 and the fourth light source 244 are located on opposite sides of the light guide unit 230. The first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 do not have to be the same light source, and may have different light emission intensities. Furthermore, the number of light sources is not particularly limited, and may be different from one another. The second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 may have the same length of arranged sides, but the number of light sources may be different.

[0131] The control unit 250 controls illumination light in the display device 100. The control unit 250 may be built into the display device 100, or may be mounted on another device connected to the display device 100. As shown in Fig. 57 , the control unit 250 includes a viewing angle detection unit 251 and a light source control unit 252.

[0132] The viewing angle detection unit 251 detects the viewing angle of the user with respect to the display surface 210a. The viewing angle θ is shown in FIG. 60. As shown in these figures, the viewing angle θ is an angle with respect to the normal N of the display surface 210a. The viewing angle detection unit 251 can detect the viewing angle θ based on the output of a line-of-sight detection sensor (not shown). The viewing angle detection unit 251 detects the detected viewing angle θ ｄ is supplied to the light source control unit 152.

[0133] The light source control unit 252 controls the light emission intensity of each of the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245. The light source control unit 252 can control the light emission intensity of each light source by adjusting the duty ratio of each light source. A specific control method by the light source control unit 252 will be described later.

[0134] The display device 200 has the above-described configuration. Note that the display device 200 is not limited to a horizontally long rectangular shape with the horizontal direction (X direction) as the long side and the vertical direction (Y direction) as the short side when viewed from the thickness direction (Z direction), as shown in FIG. 57 . The display device 100 may be a square shape with equal lengths in the horizontal direction (X direction) and the vertical direction (Y direction) when viewed from the thickness direction (Z direction), or may be a vertically long rectangular shape with the horizontal direction (X direction) as the short side and the vertical direction (Y direction) as the long side. Furthermore, the display device 100 may be a circle, an ellipse, or any other shape when viewed from the thickness direction (Z direction).

[0135] [Regarding Illumination Light] The light emitted from each of the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 will be described. The light emitted from the first light source 241 enters the first light guide plate 231 from the end surface 231a, is reflected by the reflecting sheet 236 on the back surface 231c (see Figures 61 and 62), and travels toward the light incident surface 210b. The light then exits the front surface 231b and reaches the prism sheet 237, where it is refracted primarily in the vertical direction (Y direction) and diffused in the same direction by the prism sheet 237. The light then passes through the second light guide plate 232, the third light guide plate 233, the fourth light guide plate 234, and the fifth light guide plate 235, is further diffused by the diffusion sheet 238, and enters the light incident surface 210b.

[0136] Light emitted from the second light source 242 enters the second light guide plate 232 from the end surface 232a (see FIG. 61), is refracted and diffused by the second light guide plate 232, and is emitted from the surface 232b in a diagonal direction to the right. The light then passes through the third light guide plate 233, the fourth light guide plate 234, and the fifth light guide plate 235, is further diffused by the diffusion sheet 238, and is incident on the light incident surface 210b.

[0137] Light emitted from the third light source 243 enters the third light guide plate 233 from the end surface 233a (see FIG. 62), is refracted and diffused by the third light guide plate 233, and is emitted from the surface 233b in a diagonal left direction. Subsequently, the light is further diffused by the diffusion sheet 238 and enters the light incident surface 210b.

[0138] The light emitted from the fourth light source 244 enters the fourth light guide plate 234 from the end surface 234a (see FIG. 61), is refracted and diffused by the fourth light guide plate 234, and is emitted from the surface 234b in a diagonal direction to the right. The light is then further diffused by the diffusion sheet 238 and enters the light incident surface 210b.

[0139] Light emitted from the fifth light source 245 enters the fifth light guide plate 235 from the end surface 235a (see FIG. 62), is refracted and diffused by the fifth light guide plate 235, and is emitted from the surface 235b in a diagonal left direction. Subsequently, the light is further diffused by the diffusion sheet 238 and enters the light incident surface 210b.

[0140] Looking at each light guide plate, light incident on the first light guide plate 231 from the end face 231a is emitted from the front face 231b to the back face 232c of the second light guide plate 232. Light incident on the second light guide plate 232 from the end face 232a and the back face 232c is emitted from the front face 232b to the back face 233c of the third light guide plate 233. Light incident on the third light guide plate 233 from the end face 233a and the back face 233c is emitted from the front face 233b to the back face 234c of the fourth light guide plate 234.

[0141] Light incident on the fourth light guide plate 234 from the end surface 234a and the back surface 234c is emitted from the front surface 234b to the back surface 235c of the fifth light guide plate 235. Light incident on the fifth light guide plate 235 from the end surface 235a and the back surface 235c is emitted from the front surface 235b to the light incident surface 210b.

[0142] In this manner, the light emitted from the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 is mixed and incident on the light incident surface 210b, becoming illumination light from the light incident surface 210b side of the display panel 210. Note that, as in the first embodiment, the prism sheet 237 is preferably an inverted prism type having very strong directionality.

[0143] With the above-described configuration of the light guide unit 230 and each light source, the luminance viewing angle characteristics on the display surface 210a are as follows. FIGS. 63 and 64 are graphs showing the luminance viewing angle characteristics on the display surface 210a. As shown in these figures, the luminance viewing angle characteristics of the light emitted from the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 255 are different from one another. Also, as shown in these figures, the luminance viewing angle characteristics change depending on the duty ratio of each light source, but any duty ratio can be used as the reference duty ratio. Furthermore, the luminance characteristics when each light source is used at the reference duty ratio are referred to as "target characteristics." Here, the duty ratio shown in FIG. 64 is used as the reference duty ratio.

[0144] 65 is a graph showing the luminance-viewing angle contribution ratio per unit power consumption of each light source. The luminance-viewing angle contribution ratio per unit power consumption can be calculated using the above-mentioned (Equation 1) to (Equation 3), and can be calculated similarly for the fourth light source 244 and the fourth light source 245 from the luminance and power consumption of each light source. As shown in the figure, the luminance-viewing angle contribution ratio per unit power consumption has a maximum value at a different specific viewing angle θ. In the figure, the maximum value of the luminance-viewing angle contribution ratio per unit power consumption of the first light source 241 is shown as the maximum value M １ and the maximum value of the second light source 242 is represented as the maximum value M ２ , the same maximum value of the third light source 242 is the maximum value M ３ , the same maximum value of the fourth light source 244 is the maximum value M ４ , the same maximum value of the fifth light source 245 is the maximum value M ５ The maximum value M １ The visual angle θ is 0°, and the maximum value M ２ The visual angle θ is 52°, and the maximum value M ３ The visual angle θ is −54°, and the maximum value M ４ The visual angle θ is 24°, and the maximum value M ５ The viewing angle θ at which the luminance is maximized is −24°. The luminance viewing angle contribution rate per unit power consumption of each light source gradually decreases as the viewing angle θ becomes farther from the maximum value.

[0145] [Operation of Display Device] The operation of the display device 200 according to the embodiment of the present technology will be described. The light source control unit 252 calculates the luminance viewing angle contribution rate per unit power consumption of each of the first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245, and the detected viewing angle θ ｄ The light emission intensity of each light source is controlled based on the above.

[0146] Specifically, the light source control unit 252 can control the light emission intensity of each light source using a lighting duty ratio setting. Fig. 66 is a graph showing lighting duty ratio settings for the display device 200. This lighting duty ratio setting is specified so that the target characteristics (see Fig. 64) described above are obtained according to the viewing angle θ, and so that the total power consumption of each light source is minimized based on the luminance viewing angle contribution rate per unit power consumption (see Fig. 65).

[0147] The light source control unit 252 determines the detected visible angle θ according to the lighting duty ratio setting. ｄ The light emission intensity of each light source is controlled so that the luminance value when the display surface 210a is viewed from the viewing angle θ coincides with the luminance value of the target characteristic (see FIG. 64). ｄ 10 is a graph showing the luminance of each light source when the angle is +30°. Ｖ　３０° ) is the luminance (L １　３０° ), the luminance of the second light source 242 (L ２　３０° ), the luminance of the third light source 243 (L ３　３０° ), the luminance of the fourth light source 244 (L ４　３０° ) and the fifth light source 245 (L ５　３０° ) and corresponds to the brightness of the target characteristic (see FIG. 64). ｄ The operation of the light source control unit 252 is the same as in the first embodiment, in that the light emission intensity of a light source having a large luminance viewing angle contribution rate per unit power consumption is preferentially increased.

[0148] Hereinafter, the detected visible angle θ by the light source control unit 252 ｄ 68 to 76 are graphs showing the luminance of each light source at each viewing angle.

[0149] As shown in FIG. 68, the detected viewing angle θ ｄ is 60° to the left (-60°), and the visual recognition angle range H is the detected visual recognition angle θ ｄ When the viewing angle is ±5°, light source control unit 252 sets the duty ratio of first light source 241 to 0%, the duty ratio of second light source 242 to 0%, the duty ratio of third light source 243 to 68.6%, the duty ratio of fourth light source 244 to 0%, and the duty ratio of fifth light source 245 to 0% based on the lighting duty ratio setting. As a result, the light emitted from third light source 143 matches the target characteristics, and a user viewing display surface 210a from viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio.

[0150] Furthermore, since the light sources other than the third light source 243 are not turned on at this time, the total power consumption can be reduced. Fig. 77 is a graph showing the total power consumption of each light source when the duty ratio of each light source is controlled in accordance with the lighting duty ratio setting (see Fig. 66). In this graph, the power consumption when all light sources are turned on at the reference duty ratio is set to 100%. As shown in this graph, the detected visual angle θ ｄ When the angle is 60° to the left, the same brightness can be achieved with about 40% of the power consumption compared to when all the light sources are turned on at the standard duty ratio.

[0151] Other detection visibility angles θ ｄ 69 to 76, the light source control unit 252 controls each light source so that a user viewing the display surface 210a from within the viewing angle range H can view illumination light equivalent to that when all light sources are turned on at the reference duty ratio. As shown in Fig. 77, the total power consumption of the light sources is less than 100% at any viewing angle θ, making it possible to reduce power consumption.

[0152] [Regarding Wide-Range Tracking] When a plurality of users are viewing the display surface 210a, or when a single user is viewing the display surface 210a but the amount of movement is large, the light source control unit 252 can use the lighting duty ratio setting for wide-range tracking, as in the first embodiment.ｄ The lighting duty ratio setting to be used can be selected according to the lighting conditions.

[0153] [Other Configurations of the Display Device] Other configurations of the display device 200 will be described. Figures 78 to 81 are plan views of the display device 200 having other configurations, viewed from various directions. As shown in these figures, the fourth light source 244 may be disposed below the light guide unit 230 and may face the end surface 234a of the fourth light guide plate 234, as shown in Figures 79 and 80. Furthermore, the fifth light source 245 may be disposed above the light guide unit 230 and may face the end surface 235a of the fifth light guide plate 235, as shown in Figures 79 and 80.

[0154] In this configuration, the first light source 241, the fourth light source 244, and the fifth light source 245 are located on opposite sides of the light-guiding unit 230, as shown in FIG. 78 . The first light source 241, the second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 do not have to be the same light source, and may have different light emission intensities. Furthermore, the number of light sources is not particularly limited, and may be different numbers. The second light source 242, the third light source 243, the fourth light source 244, and the fifth light source 245 have the same length of arranged sides, but the numbers may be different.

[0155] In this configuration, the light source control unit 252 controls the light emission intensities of the first light source 241, the second light source 242, and the third light source 243 in the left-right direction (X direction) to detect a visible angle θ ｄ The light source control unit 252 controls the light emission intensity of each light source so that the luminance value when the display surface 210a is viewed from the vertical direction (Y direction) coincides with the luminance value of the target characteristic. ｄ The light emission intensity of each light source is controlled so that the luminance value when viewing the display surface 210a from the horizontal direction matches the luminance value of the target characteristic. This makes it possible to reduce power consumption while maintaining luminance in accordance with the viewing angle θ not only in the horizontal direction but also in the vertical direction.

[0156] In this embodiment, the light source control unit 252 controls the light emission intensity of each light source using the duty ratio, but it is also possible to control the light emission intensity of each light source by adjusting something other than the duty ratio, such as the current value.

[0157] (Hardware configuration of control unit) The hardware configuration of the information processing device 300 constituting the control unit 150 in the first embodiment and the control unit 250 in the second embodiment of the present technology will be described. Note that the control unit 150 and the control unit 250 may be an information processing unit provided in an independent information processing device or display device as long as they include at least a part of the hardware configuration described below. Fig. 82 is a schematic diagram showing the hardware configuration of this information processing device 300.

[0158] As shown in the figure, the information processing device 300 incorporates a CPU (Central Processing Unit) 1001 and a GPU (Graphics Processing Unit) 1002. An input / output interface 1006 is connected to the CPU 1001 and the GPU 1002 via a bus 1005. A ROM (Read Only Memory) 1003 and a RAM (Random Access Memory) 1004 are connected to the bus 1005.

[0159] The input / output interface 1006 is connected to an input unit 1007 including input devices such as a keyboard and a mouse through which a user inputs operation commands, an output unit 1008 that outputs a processing operation screen and images of processing results to a display device, a storage unit 1009 including a hard disk drive or the like that stores programs and various data, and a communication unit 1010 including a LAN (Local Area Network) adapter or the like that executes communication processing via a network typified by the Internet. Also connected is a drive 1011 that reads and writes data from a removable storage medium 1012 such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory.

[0160] The CPU 1001 executes various processes in accordance with a program stored in a ROM 1003 or a program read from a removable storage medium 1012 such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, installed in a storage unit 1009, and loaded from the storage unit 1009 into a RAM 1004. The RAM 1004 also stores data necessary for the CPU 1001 to execute various processes as appropriate. The GPU 1002 executes calculations necessary for image rendering under the control of the CPU 1001.

[0161] In the information processing device 300 configured as described above, the CPU 1001 performs the above-described series of processes by, for example, loading a program stored in the memory unit 1009 into the RAM 1004 via the input / output interface 1006 and the bus 1005 and executing it.

[0162] The program executed by information processing device 300 can be provided by being recorded on removable storage medium 1012 such as a package medium, for example. The program can also be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

[0163] Furthermore, in the information processing device 300, the program can be installed in the storage unit 1009 via the input / output interface 1006 by attaching the removable storage medium 1012 to the drive 1011. The program can also be received by the communication unit 1010 via a wired or wireless transmission medium and installed in the storage unit 1009. Alternatively, the program can be installed in advance in the ROM 1003 or the storage unit 1009.

[0164] The program executed by the information processing device 300 may be a program that is processed chronologically in the order described in this disclosure, or may be a program that is processed in parallel or at the required timing, such as when called.

[0165] Furthermore, the entire hardware configuration of the information processing device 300 does not have to be installed in one device, and the information processing device 300 may be configured by multiple devices. Furthermore, part of the hardware configuration of the information processing device 300 may be installed in multiple devices connected via a network.

[0166] The present technology can also be configured as follows.

[0167] (1) A display device comprising: a display panel having a display surface and a light incident surface opposite to the display surface, the display panel transmitting light incident on the light incident surface and emitting it from the display surface, a first light source, a second light source, and a third light source, a light guide unit guiding the light incident from each of the first to third light sources to make it incident on the light incident surface and having the light emitted from the first to third light sources have mutually different luminance viewing angle characteristics on the display surface, and a light source controller that controls emission intensities of the first to third light sources based on a luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle that is a detected viewing angle for the display surface, where the luminance viewing angle contribution rate is a contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle. (2) The display device according to (1), wherein the light source controller preferentially increases the emission intensity of a light source among the first to third light sources that has a larger contribution rate at the detected viewing angle. (3) The display device according to (2), wherein the light source control unit increases the emission intensity of one of the first to third light sources, which has a larger contribution rate at the detection viewing angle, more than the emission intensity of another light source, which has a smaller contribution rate at the detection viewing angle. (4) The display device according to (2) or (3), wherein the light source control unit controls the emission intensities of the first to third light sources so that, when a viewing angle characteristic of luminance on the display surface when the first to third light sources are caused to emit light simultaneously at specific emission intensities is a target characteristic, the luminance value when the display surface is viewed from the detection viewing angle coincides with the luminance value of the target characteristic. (5) The display device according to any one of (1) to (4), wherein the light source control unit controls the emission intensities of the first to third light sources so that, when a viewing angle characteristic of luminance on the display surface when the first to third light sources are caused to emit light simultaneously at specific emission intensities is a target characteristic, the luminance value when the display surface is viewed from a viewing angle within a viewing angle range that includes the detection viewing angle coincides with the luminance value of the target characteristic.(6) The display device according to (5) above, wherein the light source control unit is capable of switching between a first state in which the light emission intensities of the first to third light sources are controlled so that a luminance value when the display surface is viewed from a viewing angle within a first viewing angle range matches a luminance value of the target characteristic, and a second state in which the light emission intensities of the first to third light sources are controlled so that a luminance value when the display surface is viewed from a viewing angle within a second viewing angle range wider than the first viewing angle range matches the luminance value of the target characteristic. (7) The display device according to any one of (1) to (6) above, wherein the luminance viewing angle contribution ratios per unit power consumption of the first to third light sources have maximum values ​​at different specific viewing angles and gradually decrease as the viewing angle becomes farther from the specific viewing angle. (8) The display device according to (7), wherein, when causing only the two light sources to emit light between specific viewing angles where two light sources among the first to third light sources have close maximum values, the light source control unit increases the emission intensity of one light source and decreases the emission intensity of the other light source in accordance with the detected viewing angle. (9) The display device according to (8), wherein, when causing only the two light sources to emit light, the light source control unit decreases the emission intensity change rate of the light source with the higher contribution rate of the two light sources and increases the emission intensity change rate of the light source with the lower contribution rate when bringing the emission intensity of one light source closer to zero in accordance with the detected viewing angle.(10) The display device according to any one of (1) to (9), wherein the light guide unit is configured by stacking a first light guide plate that guides light incident from the first light source and makes it incident on the light incident surface, a second light guide plate that guides light incident from the second light source and makes it incident on the light incident surface, and a third light guide plate that guides light incident from the third light source and makes it incident on the light incident surface, wherein the first light guide plate has a first end face facing the first light source, a first front surface that is a main surface facing the display panel, and a first back surface that is a main surface opposite to the first front surface, wherein the second light guide plate has a second end face facing the second light source, a second main surface that is a main surface facing the display panel, and a second back surface that is a main surface opposite to the second front surface, and wherein the third light guide plate has a third end face facing the third light source, a third main surface that is a main surface facing the display panel, and a third back surface that is a main surface opposite to the third front surface. (11) The display device according to (10) above, wherein the first light guide plate is arranged farthest from the display panel among the first to third light guide plates, and light incident from the first end face is emitted from the first front surface to the second rear face, the second light guide plate is arranged between the first light guide plate and the display panel, and light incident from the second end face and light incident from the second rear face are emitted from the second front surface to the third rear face, and the third light guide plate is arranged between the second light guide plate and the display panel, and light incident from the third end face and light incident from the third rear face are emitted from the third front surface to the light incident surface. (12) The display device according to (11) above, wherein the light guide unit further includes a prism sheet arranged between the first light guide plate and the second light guide plate, and apexes of prisms of the prism sheet abut against the first front face. (13) The display device according to (12), wherein the first light source is a plurality of point light sources arranged along a horizontal direction, the second light source and the third light source are a plurality of point light sources arranged along a vertical direction, and the second light source and the third light source are located on opposite sides of the light guide unit.(14) The display device according to any one of (1) to (3), further comprising: a fourth light source; and a fifth light source, wherein the light guide unit guides light incident from each of the first to fifth light sources to make it incident on the light incident surface, and the light emitted from each of the first to fifth light sources has a luminance viewing angle characteristic on the display surface that is different from one another, and the light source control unit controls the emission intensity of each of the first to fifth light sources based on a luminance viewing angle contribution rate per unit power consumption of each of the first to fifth light sources and a detected viewing angle that is a detected viewing angle with respect to the display surface. (15) The display device according to (14), wherein the first light source is a plurality of point light sources arranged along a horizontal direction, and the second to fifth light sources are a plurality of point light sources arranged along a vertical direction, and the second light source and the fourth light source and the third light source and the fifth light source are located on opposite sides of the light guide unit. (16) The display device according to (14), wherein the first light source, the fourth light source, and the fifth light source are a plurality of point light sources arranged along a horizontal direction, the second light source and the third light source are a plurality of point light sources arranged along a vertical direction, and the first light source, the fourth light source, and the fifth light source are located on opposite sides of the light guide unit. (17) The display device according to any one of (1) to (16), further comprising a viewing angle detection unit that detects the detected viewing angle.(18) A light emitting device comprising: a first light source; a second light source; a third light source; a display surface; and a light guide unit disposed on the light incident surface side of a display panel having a light incident surface opposite to the display surface, the light guide unit transmitting light incident on the light incident surface and emitting light from the display surface, the light guide unit guiding the light incident from each of the first to third light sources to make it incident on the light incident surface, and the light emitted from the first to third light sources having mutually different luminance viewing angle characteristics on the display surface; and a light source control unit controlling the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and based on a detected viewing angle which is a detected viewing angle for the display surface, where the luminance viewing angle contribution rate is a contribution rate of the luminance of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle. (19) A light emission control method for controlling the light emission intensities of each of the first to third light sources in a light emitting device including a first light source, a second light source, a third light source, and a light guide unit, wherein the light guide unit has a display surface and a light incident surface opposite to the display surface, and is arranged on the light incident surface side of a display panel that transmits light incident on the light incident surface and causes light to exit from the display surface, and guides the light incident from each of the first light source, the second light source, and the third light source to enter the light incident surface, and the light emitted from each of the first to third light sources has mutually different luminance viewing angle characteristics on the display surface, and the light emission intensities of each of the first to third light sources are controlled based on the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle that is a detected viewing angle for the display surface, where the luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance viewing angle contribution rate.(20) A light-emitting control program that controls the light emission intensity of each of the first to third light sources in a light-emitting device that includes a first light source, a second light source, a third light source, and a light-guiding unit, wherein the light-guiding unit has a display surface and a light-incident surface opposite to the display surface, and is arranged on the light-incident surface side of a display panel that transmits light incident on the light-incident surface and causes light to exit from the display surface, and guides the light incident from each of the first light source, the second light source, and the third light source to enter the light-incident surface, and the light emitted from each of the first to third light sources has a luminance-viewing-angle characteristic on the display surface that is different from one another, and the light-emitting control program causes an information processing device to operate as a light source control unit that controls the light emission intensity of each of the first to third light sources based on the luminance-viewing-angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle that is a detected viewing angle with respect to the display surface, where the luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance-viewing-angle contribution rate.

[0168] DESCRIPTION OF SYMBOLS 100, 200... Display device 110, 210... Display panel 120, 220... Light-emitting device 130, 230... Light guide unit 131, 231... First light guide plate 132, 232... Second light guide plate 133, 233... Third light guide plate 234... Fourth light guide plate 235... Fifth light guide plate 135, 237... Prism sheet 141, 241... First light source 142, 242... Second light source 143, 243... Third light source 244... Fourth light source 245... Fifth light source 150, 250... Control unit 151, 251... Viewing angle detection unit 152, 252... Light source control unit

Claims

1. A display device comprising: a display panel having a display surface and a light incident surface opposite to the display surface, the display panel transmitting light that is incident on the light incident surface and causing it to exit from the display surface; a first light source, a second light source, a third light source; a light guide unit that guides light incident from each of the first to third light sources to be incident on the light incident surface, and the light emitted from the first to third light sources has mutually different luminance viewing angle characteristics on the display surface; and a light source control unit that controls the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and based on a detected viewing angle, which is the detected viewing angle for the display surface, where the luminance viewing angle contribution rate is the contribution rate of the luminance of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle.

2. A display device according to claim 1, wherein the light source control unit preferentially increases the emission intensity of the light source having the largest contribution rate at the detected viewing angle among the first to third light sources.

3. A display device according to claim 2, wherein the light source control unit increases the emission intensity of the light source having the larger contribution rate at the detected viewing angle among the first to third light sources, more than the emission intensity of the light source having the smaller contribution rate.

4. A display device according to claim 2, wherein the light source control unit controls the emission intensities of the first to third light sources so that, when the viewing angle characteristic of the luminance on the display surface when the first to third light sources are simultaneously made to emit light at a specific emission intensity is set as a target characteristic, the luminance value when the display surface is viewed from the detected viewing angle matches the luminance value of the target characteristic.

5. A display device according to claim 2, wherein the light source control unit controls the emission intensities of the first to third light sources so that, when the viewing angle characteristic of the luminance on the display surface when the first to third light sources are simultaneously made to emit light at a specific emission intensity is set as a target characteristic, the luminance value when the display surface is viewed from a viewing angle within a viewing angle range that is an angle range that includes the detected viewing angle matches the luminance value of the target characteristic.

6. A display device according to claim 5, wherein the light source control unit is capable of switching between a first state in which the light emission intensities of the first to third light sources are controlled so that the luminance value when the display surface is viewed from a viewing angle within a first viewing angle range matches the luminance value of the target characteristic, and a second state in which the light emission intensities of the first to third light sources are controlled so that the luminance value when the display surface is viewed from a viewing angle within a second viewing angle range wider than the first viewing angle range matches the luminance value of the target characteristic.

7. A display device according to claim 1, wherein the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources has a maximum value at a different specific viewing angle, and gradually decreases as the viewing angle moves away from the specific viewing angle.

8. A display device according to claim 7, wherein the light source control unit increases the emission intensity of one light source and decreases the emission intensity of the other light source in accordance with the detected viewing angle when two of the first to third light sources whose maximum values ​​are close to each other are made to emit light between specific viewing angles where the respective maximum values ​​are achieved.

9. A display device according to claim 8, wherein the light source control unit, when causing only the two light sources to emit light, reduces the rate of change in the emission intensity of the light source with the higher contribution rate of the two light sources and increases the rate of change in the emission intensity of the light source with the lower contribution rate when bringing the emission intensity of one of the two light sources closer to zero in accordance with the detected viewing angle.

10. A display device according to claim 1, wherein the light guide unit is configured by stacking a first light guide plate that guides light incident from the first light source and makes it incident on the light incident surface, a second light guide plate that guides light incident from the second light source and makes it incident on the light incident surface, and a third light guide plate that guides light incident from the third light source and makes it incident on the light incident surface, wherein the first light guide plate has a first end face facing the first light source, a first front surface that is the main surface facing the display panel, and a first back surface that is the main surface opposite the first front surface, wherein the second light guide plate has a second end face facing the second light source, a second main surface that is the main surface facing the display panel, and a second back surface that is the main surface opposite the second front surface, and wherein the third light guide plate has a third end face facing the third light source, a third main surface that is the main surface facing the display panel, and a third back surface that is the main surface opposite the third front surface.

11. A display device according to claim 10, wherein the first light guide plate is arranged farthest from the display panel among the first to third light guide plates, and light incident from the first edge surface is emitted from the first front surface to the second rear surface; the second light guide plate is arranged between the first light guide plate and the display panel, and light incident from the second edge surface and light incident from the second rear surface are emitted from the second front surface to the third rear surface; and the third light guide plate is arranged between the second light guide plate and the display panel, and light incident from the third edge surface and light incident from the third rear surface are emitted from the third front surface to the light incident surface.

12. A display device according to claim 11, wherein the light guide unit further comprises a prism sheet disposed between the first light guide plate and the second light guide plate, and the prism sheet has prisms whose apexes abut against the first surface.

13. A display device according to claim 12, wherein the first light source is a plurality of point light sources arranged along the horizontal direction, the second light source and the third light source are a plurality of point light sources arranged along the vertical direction, and the second light source and the third light source are located on opposite sides of the light guide unit.

14. A display device according to claim 1, further comprising a fourth light source and a fifth light source, wherein the light guide unit guides light incident from each of the first to fifth light sources and makes it incident on the light incident surface, and the light emitted from each of the first to fifth light sources has different luminance viewing angle characteristics on the display surface, and the light source control unit controls the light emission intensity of each of the first to fifth light sources based on the luminance viewing angle contribution rate per unit power consumption of each of the first to fifth light sources and a detected viewing angle, which is the detected viewing angle relative to the display surface.

15. A display device according to claim 14, wherein the first light source is a plurality of point light sources arranged along the horizontal direction, the second to fifth light sources are a plurality of point light sources arranged along the vertical direction, and the second and fourth light sources and the third and fifth light sources are located on opposite sides of the light guide unit.

16. A display device according to claim 14, wherein the first light source, the fourth light source and the fifth light source are a plurality of point light sources arranged along the horizontal direction, the second light source and the third light source are a plurality of point light sources arranged along the vertical direction, and the first light source, the fourth light source and the fifth light source are located on opposite sides of the light guide unit.

17. A display device according to claim 1, further comprising a viewing angle detection unit that detects the detected viewing angle.

18. A light emitting device comprising: a first light source, a second light source, a third light source; a display surface; and a light guide unit disposed on the light incident surface side of a display panel having a light incident surface opposite to the display surface, the light transmitting the light incident thereon and emitting it from the display surface, the light guide unit guiding the light incident from each of the first to third light sources to make it incident on the light incident surface, the light emitted from the first to third light sources having mutually different luminance viewing angle characteristics on the display surface; and a light source control unit controlling the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources based on a detected viewing angle which is the detected viewing angle for the display surface, where the luminance viewing angle contribution rate is the contribution rate of the luminance of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle.

19. A light emission control method for controlling the light emission intensity of each of the first to third light sources in a light emitting device comprising a first light source, a second light source, a third light source, and a light guide unit, wherein the light guide unit has a display surface and a light incident surface opposite to the display surface, and is arranged on the light incident surface side of a display panel that transmits light incident on the light incident surface and emits it from the display surface, and guides light incident from each of the first light source, the second light source, and the third light source to make it incident on the light incident surface, and the light emitted from each of the first to third light sources has mutually different luminance viewing angle characteristics on the display surface, and where the luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance viewing angle contribution rate, the light emission intensity of each of the first to third light sources is controlled based on the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle which is the detected viewing angle for the display surface.

20. A light-emitting control program for controlling the light emission intensity of each of the first to third light sources in a light-emitting device comprising a first light source, a second light source, a third light source, and a light-guiding unit, wherein the light-guiding unit has a display surface and a light-incident surface opposite to the display surface, and is arranged on the light-incident surface side of a display panel that transmits light incident on the light-incident surface and emits it from the display surface, and guides light incident from each of the first light source, the second light source, and the third light source to make it incident on the light-incident surface, and the light emitted from each of the first to third light sources has mutually different luminance viewing angle characteristics on the display surface, and where the luminance contribution rate of each of the first to third light sources to the luminance when the display surface is viewed from each viewing angle is defined as a luminance viewing angle contribution rate, the light-emitting control program causes an information processing device to operate as a light source control unit that controls the light emission intensity of each of the first to third light sources based on the luminance viewing angle contribution rate per unit power consumption of each of the first to third light sources and a detected viewing angle, which is the detected viewing angle for the display surface.

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