JP2014102275A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct aberration to accurately display an image.SOLUTION: A display device displays an image toward a view point of an observer, and includes a backlight unit that emits parallel light and a plurality of prisms arranged side by side in a horizontal direction. The display device further includes a dioptric system that deflects light from the backlight unit in the horizontal direction to be directed toward an observation direction, a light collection optical system that collects the light transmitted through the dioptric system into the view point of the observer, and a display panel that transmits the light from the light collection optical system to display an image. The plurality of prisms have a refractive angle larger in an area farther from an optical axis than in an area closer to the optical axis.

Description

  The present invention relates to a display device.

There is known a stereoscopic display device for the naked eye that uses a lenticular to display different images to the left and right eyes of an observer who is not wearing a dedicated lens.
[Prior art documents]
[Patent Literature]
[Patent Document 1] JP 2012-133024 A

  The stereoscopic display device of Patent Document 1 widens the viewing angle by refracting parallel light from a backlight with a prism and condensing the refracted light onto the observer's eyes with a lens. However, in such a stereoscopic display device, since the light incident on the lens is light obliquely after being refracted by the prism, the aberration due to the lens has increased.

  In the first aspect of the present invention, the display device displays an image toward the observer's viewpoint, and includes a backlight unit that emits parallel light and a plurality of prisms arranged in a horizontal direction, A refracting optical system that refracts light from the backlight unit in a horizontal direction so as to go in the observation direction, a condensing optical system that condenses the light transmitted through the refracting optical system to an observer's viewpoint, and the refraction A display panel that transmits light from the optical system and displays an image, and the plurality of prisms have a gradual refraction angle in a region farther from the optical axis than in a region near the optical axis. I will provide a.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The structure of the display apparatus 10 which concerns on this embodiment is shown. The arrangement of the display panel 20, the irradiation optical system 22, the prism panel 23, the condensing optical system 24, the lenticular 25, and the vertical diffusion unit 26 provided in the display device 10 according to the present embodiment is shown. The structure at the time of seeing the display apparatus 10 which concerns on this embodiment from the upper side is shown. The structure of the display apparatus 10 and the optical path from the light source pattern 40 to a 1st observer's viewpoint are shown. The structure of the display apparatus 10 and the optical path from the light source pattern 40 to a 2nd observer's viewpoint are shown. An example of an optical path when the condensing optical system 24 condenses the parallel light refracted by the refractive optical system having a uniform refraction angle is shown. An example of an optical path in the case where the refractive optical system 51 having a gradual refraction angle in the peripheral portion is gentler than the portion close to the optical axis is shown. An example of the integrally formed lens 70 is shown. An example of a large cylindrical Fresnel lens 72 and an integrally formed lens 70 that is a part of the large cylindrical Fresnel lens 72 is shown. An example of the cut-out position in the case of cutting out the integrally formed lenses 70-1 to 70-9 corresponding to the respective viewpoints from the large cylindrical Fresnel lens 72 is shown. An example of the optical path in the case where the lenticular 25 and the condensing optical system 24 are arranged in this order from the light source side is shown. An example of the optical path in the case where the condensing optical system 24 and the lenticular 25 are arranged in this order from the light source side is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration of a display device 10 according to the present embodiment. FIG. 2 shows an arrangement of the display panel 20, the irradiation optical system 22, the prism panel 23, the condensing optical system 24, the lenticular 25, and the vertical diffusion unit 26 provided in the display device 10 according to the present embodiment. FIG. 3 shows a configuration when the display device 10 according to the present embodiment is viewed from above.

  The display device 10 simultaneously displays a stereoscopic image to a plurality of observers who are not wearing image separation glasses. For example, in the case where the observation range is divided into right and left parts, the display device 10 uses the right eye for each of the first observer located in the left area and the second observer located in the right area. The right eye image is irradiated, and the left eye image is irradiated to the left eye.

  As shown in FIGS. 1 to 3, the display device 10 includes a display panel 20, a projector unit 21, an irradiation optical system 22, a prism panel 23, a condensing optical system 24, a lenticular 25, and a vertical direction. And a diffusion unit 26. The display panel 20 transmits light applied to the back surface and displays a right-eye image and a left-eye image to a plurality of observers positioned on the front surface side.

  The projector unit 21 is provided on the back side of the display panel 20. The projector unit 21 emits light to the back surface of the display panel 20. The projector unit 21 can project an optical image having a preset pattern onto the back side of the display panel 20 by receiving an image signal from the outside.

  In the present embodiment, the projector unit 21 includes a right-eye projector 31, a left-eye projector 32, and a beam splitter 33. The right-eye projector 31 emits light that passes through the display panel 20 and the like toward the right eye of the observer. The left-eye projector 32 emits light that passes through the display panel 20 and the like toward the left eye of the observer. The beam splitter 33 transmits one of the light emitted from the right-eye projector 31 and the light emitted from the left-eye projector 32 and reflects the other, whereby the light emitted from the right-eye projector 31. And the light emitted from the left-eye projector 32 are combined, and the combined light is irradiated on the back surface of the display panel 20.

  The irradiation optical system 22 condenses the light emitted from the projector unit 21 into parallel light. The irradiation optical system 22 projects parallel light onto the back surface of the display panel 20.

  For example, the irradiation optical system 22 includes a front-stage cylindrical lens 34 and a rear-stage cylindrical lens 35. The front-stage cylindrical lens 34 condenses the light from the projector unit 21 in the first direction (in this example, the vertical direction of the display panel 20). The rear-stage cylindrical lens 35 condenses the light transmitted through the front-stage cylindrical lens 34 in a direction that is 90 degrees different from the first direction (in this example, the horizontal direction of the display panel 20). In the present example, the front cylindrical lens 34 and the rear cylindrical lens 35 are each a Fresnel lens.

  The projector unit 21 and the irradiation optical system 22 can project parallel light on the back side of the display panel 20. In addition, the projector unit 21 emits light of a planar light emission pattern set in advance according to the input image signal, and projects a light source pattern 40 having a plurality of light source images on the back side of the display panel 20. The projector unit 21 and the irradiation optical system 22 function as a backlight unit having a plurality of light sources that emit parallel light. The light source pattern 40 projected on the back surface of the display panel 20 will be further described with reference to FIGS.

  The prism panel 23 is disposed between the irradiation optical system 22 and the display panel 20, and enters parallel light emitted from the projector unit 21 and the irradiation optical system 22 from the back surface. The prism panel 23 refracts the parallel light incident from the back surface in a direction toward each of a plurality of regions having different horizontal directions.

  In this example, the prism panel 23 is refracted in two directions: a direction toward the left region and a direction toward the right region when the observation range is divided into left and right parts. Since such a prism panel 23 refracts parallel light, chromatic aberration caused by refraction can be reduced.

  In the present embodiment, the prism panel 23 includes a plurality of refractive optical systems 51 having different refracting directions. The plurality of refractive optical systems 51 are provided corresponding to the observation directions toward the respective regions when the observation range is divided into a plurality in the horizontal direction. Each of the plurality of refractive optical systems 51 includes a plurality of prisms 52 arranged in a horizontal direction at a predetermined pitch, and refracts the parallel light from the irradiation optical system 22 so as to be directed in a corresponding observation direction.

  Each of the plurality of refractive optical systems 51 has a strip shape extending in the horizontal direction of the display panel 20. The plurality of refractive optical systems 51 having such a shape are arranged side by side in the vertical direction.

  In this example, the prism panel 23 includes a plurality of first refractive optical systems 51-1 that refract parallel light toward the left observation direction, and a plurality of second refraction light that refracts parallel light toward the right observation direction. Refracting optical system 51-2. In the prism panel 23, the first refractive optical system 51-1 and the second refractive optical system 51-2 are alternately arranged in the vertical direction.

  Furthermore, the plurality of prisms 52 included in each of the plurality of refractive optical systems 51 has an optical axis that is closer to the optical axis of the condensing optical system 24 (in this example, the center axis of the display panel 20). The refraction angle is gentler in the region far from the region. Thereby, the plurality of prisms 52 can correct in advance the coma aberration generated in the subsequent condensing optical system 24. Details thereof will be further described with reference to FIGS.

  The condensing optical system 24 is provided on the back side of the display panel 20 and condenses the light transmitted through each refractive optical system 51 included in the prism panel 23 to the corresponding observer's viewpoint. The condensing optical system 24 is, for example, a cylindrical Fresnel lens that condenses light in the horizontal direction.

  In this example, the condensing optical system 24 condenses the light refracted by the first refractive optical system 51-1 to the viewpoint of the first observer located in the left region. Furthermore, the condensing optical system 24 condenses the light refracted by the second refractive optical system 51-2 to the viewpoint of the second observer located in the right region.

  Further, in this case, the condensing optical system 24 uses the light emitted from the right-eye projector 31 to the right of each of a plurality of observers (in this example, the first observer and the second observer). Focus on the eyes. The condensing optical system 24 condenses the light emitted from the left-eye projector 32 to the left eyes of a plurality of observers (in this example, the first observer and the second observer). To do.

  The lenticular 25 is provided between the condensing optical system 24 and the display panel 20 and makes light from the condensing optical system 24 incident from the back surface. The lenticular 25 separates the light from the condensing optical system 24 into a plurality of light beams corresponding to a plurality of viewpoints arranged in the horizontal direction. For example, the lenticular 25 includes a plurality of strip-shaped cylindrical lenses extending in the vertical direction of the display panel 20. Each of the plurality of cylindrical lenses separates (diverges) light incident on the back surface in the horizontal direction. The lenticular 25 is formed by arranging a plurality of such cylindrical lenses in the horizontal direction.

  Such a lenticular 25 separates the light refracted by the refractive optical system 51 further toward each of a plurality of viewpoints. Therefore, the lenticular 25 can increase the number of viewpoints that can be observed by the display device 10 such as 2 viewpoints, 5 viewpoints, 7 viewpoints, and 9 viewpoints in each region in which the observation range is largely divided in the horizontal direction. In this example, the lenticular 25 can increase the number of observable viewpoints, such as 2 viewpoints, 5 viewpoints, 7 viewpoints, and 9 viewpoints, in each of the left area and the right area of the display device 10. .

  The vertical diffusing unit 26 is provided between the lenticular 25 and the display panel 20 and makes light from the lenticular 25 incident from the back surface. The vertical diffusion unit 26 transmits light from the lenticular 25 and diffuses it in the vertical direction. Thereby, even if the refractive optical system 51 refracting in a specific observation direction is discretely arranged in the vertical direction, the vertical diffusion unit 26 makes light directed to the specific observation direction uniform in the vertical direction. The entire back surface of the display panel 20 can be irradiated.

  As an example, the vertical diffusion unit 26 includes a first vertical diffusion plate 55 and a second vertical diffusion plate 56. The first vertical diffusion plate 55 is provided on the lenticular 25 side and diffuses light from the lenticular 25 in the vertical direction. The second vertical diffusion plate 56 is provided on the display panel 20 side, and further diffuses light from the first vertical diffusion plate 55 in the vertical direction.

  Here, the diffusion plate has a configuration in which a plurality of cylindrical lenses extending in a direction orthogonal to the diffusing direction are arranged in the diffusing direction. Therefore, the light transmitted through one diffusion plate has a light amount at the center of each cylindrical lens that is larger than that of the surroundings, resulting in some unevenness. Therefore, the second vertical diffusion plate 56 is a distance at which at least a part of light spots (regions in which the amount of light is larger than the surroundings) adjacent to each other in the vertical direction formed by the first vertical diffusion plate 55 are overlapped. As described above, the first vertical diffusion plate 55 is disposed apart from the first vertical diffusion plate 55. As a result, the first vertical diffusion plate 55 and the second vertical diffusion plate 56 can emit uniform light more evenly in the vertical direction than when the light is diffused by one diffusion plate.

  The display panel 20 displays an image according to the light from the vertical diffusion unit 26. In this case, the display panel 20 displays the right-eye image according to the light emitted from the right-eye projector 31, and displays the left-eye image according to the light emitted from the left-eye projector 32. .

  For example, it is assumed that the right-eye projector 31 emits light having a first polarization, and the left-eye projector 32 emits light having a second polarization that is orthogonal to or opposite to the first polarization. In this case, the display panel 20 has a region that transmits the first polarized light and blocks the second polarized light, and a display region that transmits the second polarized light and blocks the first polarized light. Then, the display panel 20 displays the right-eye image given to the right eye in a region that transmits the first polarized light and blocks the second polarized light, transmits the second polarized light, and blocks the first polarized light. A left-eye image to be given to the left eye is displayed in the area to be displayed.

  Further, for example, it is assumed that the right-eye projector 31 and the left-eye projector 32 emit light at different timings alternately at regular time intervals. In this case, the display panel 20 displays the right-eye image given to the right eye at the light emission timing of the right-eye projector 31, and displays the left-eye image given to the left eye at the light emission timing of the left-eye projector 32.

  The display device 10 configured as described above can display the right-eye image only for the observer's right eye, and can display the left-eye image only for the observer's left eye. Thus, according to the display device 10, a stereoscopic image can be displayed to an observer who is not wearing image separation glasses.

  FIG. 4 shows a configuration of the display device 10 and an optical path from the light source pattern 40 to the viewpoint of the first observer. FIG. 5 shows a configuration of the display device 10 and an optical path from the light source pattern 40 to the viewpoint of the second observer.

  The projector unit 21 and the irradiation optical system 22 have a light source pattern 40 including images of a plurality of light sources each emitting parallel light with respect to the back side of the display panel 20 (more specifically, the back side of the prism panel 23). Project. More specifically, the right-eye projector 31 is on the back surface of the prism panel 23 where the emitted light passes through the prism panel 23, the condensing optical system 24, and the lenticular 25 toward the right eye of each observer. Each of the plurality of right-eye light source images 41 is projected onto each of the plurality of positions. The left-eye projector 32 passes through the prism panel 23, the condensing optical system 24, and the lenticular 25 to the left eye of each observer at a plurality of positions on the back surface of the prism panel 23. Each of the left eye light source images 42 is projected onto each of them.

  In this example, as shown in FIG. 4, the projector unit 21 emits light toward the first observer located on the left side of the observation region on the back surface of the first refractive optical system 51-1. The first right-eye light source image 41-1 and the first left-eye light source image 42-1 are projected. As a result, the light emitted from the first right-eye light source image 41-1 is converted into the first refractive optical system 51-1, the condensing optical system 24, the lenticular 25, the vertical diffusion unit 26, and the display panel 20. Are sequentially collected and focused on the right eye of the first observer. The light emitted from the first left-eye light source image 42-1 passes through the first refractive optical system 51-1, the condensing optical system 24, the lenticular 25, the vertical diffusion unit 26, and the display panel 20. It passes sequentially and is focused on the left eye of the first observer.

  In addition, as shown in FIG. 5, the projector unit 21 emits light toward the second observer located on the right side of the observation region on the back surface of the second refractive optical system 51-2. The right-eye light source image 41-2 and the second left-eye light source image 42-2 are projected. Thereby, the light emitted from the image 41-2 of the second right eye light source is converted into the second refractive optical system 51-2, the condensing optical system 24, the lenticular 25, the vertical diffusion unit 26, and the display panel 20. Are sequentially collected and focused on the right eye of the second observer. The light emitted from the second left-eye light source image 42-2 passes through the second refractive optical system 51-2, the condensing optical system 24, the lenticular 25, the vertical diffusing unit 26, and the display panel 20. It passes sequentially and is focused on the left eye of the second observer.

  As described above, the projector unit 21 projects the light source pattern 40 on the back side of the display panel 20 to display the right-eye image only for the right eye of the observer, and for the left eye of the observer. Only the left-eye image can be displayed.

  Note that the projector unit 21 may project a light source pattern 40 having an image of a light source for each of a plurality of colors (for example, red, blue, and green) so as to become white light when combined. The position of the image of the light source for each color is adjusted so that each image faces the right eye or the left eye. As a result, when an image of a white light source is projected, the projector unit 21 projects the light source of each color at a position where chromatic aberration is corrected in advance even if the optical path shifts for each color due to chromatic aberration. can do.

  FIG. 6 shows an example of an optical path when a refractive optical system having a uniform refraction angle is used. When parallel light obliquely to the optical axis is incident on the lens, the position of the light beam that has passed through the central portion of the lens on the image plane (viewpoint surface) and the image of the light beam that has passed through the peripheral portion of the lens There is a deviation from the position on the surface due to aberration (coma aberration). Therefore, when the condensing optical system 24 condenses oblique parallel light refracted by the refractive optical system 51 as in the present embodiment, the refraction angle of each prism 52 included in the refractive optical system 51 is If all are uniform, as shown in FIG. 6, the light beam passing near the optical axis of the condensing optical system 24 and the light beam passing through a position far from the optical axis of the condensing optical system 24 are on the image plane. Deviation occurs in position.

  FIG. 7 shows an example of an optical path when the refractive optical system 51 is used in which the refraction angle is gentler in the peripheral portion than in the center of the optical axis. Here, in this embodiment, the refraction angles of the plurality of prisms 52 included in the refractive optical system 51 are refracted in the peripheral portion far from the optical axis than in the central portion near the optical axis of the condensing optical system 24. The angle is moderate (obtuse). As a result, the plurality of prisms 52 can make the light flux corrected in advance for coma generated in the condensing optical system 24 enter the condensing optical system 24.

  Further, the refraction angles of the plurality of prisms 52 may be adjusted for each position in the horizontal direction so as to correct in advance the coma aberration generated in the condensing optical system 24. As a result, the plurality of prisms 52 are arranged such that the position of the light beam that has passed through the central portion of the condensing optical system 24 and the position of the light beam that has passed through the peripheral portion of the condensing optical system 24 on a predetermined image surface. The position on the image plane can be matched.

  Thus, the display device 10 can reduce the aberration generated in the condensing optical system 24 and show a clear image to the observer.

  FIG. 8 shows an example of the integrally formed lens 70. FIG. 9 shows an example of a large cylindrical Fresnel lens 72 and an integrally formed lens 70 that is a part of the large cylindrical Fresnel lens 72. FIG. 10 shows an example of the cutout position when the integrally formed lenses 70-1 to 70-9 corresponding to the respective viewpoints are cut out from the large cylindrical Fresnel lens 72.

  In this embodiment, the condensing optical system 24 (cylindrical Fresnel lens) and the prism panel 23 may be integrally formed. In other words, in the present embodiment, the display device 10 includes, as shown in FIG. 8, a composite panel 74 that is a lens in which a condensing optical system 24 (cylindrical Fresnel lens) and a prism panel 23 are integrally formed. It may replace with the panel 23 and the condensing optical system 24, and may be provided. Thereby, the display device 10 can be easily manufactured with fewer optical members.

  Here, as shown in FIG. 9, a part of the lens configuration in the vertical direction in the composite panel 74 (integrated lens 70) is a large cylindrical Fresnel lens whose horizontal direction is larger than the horizontal width of the integrally formed lens 70. 72 has the same shape as a part of 72. The large cylindrical Fresnel lens 72 has a focal length that matches the distance from the integrally formed lens 70 to the viewpoint.

  Further, the composite panel 74 has a configuration in which a plurality of integrally formed lenses 70 having different condensing positions in the horizontal direction are arranged side by side in the vertical direction. Therefore, for example, when manufacturing the composite panel 74 for condensing each of the nine viewpoints having different horizontal positions, as shown in FIG. A shape obtained by cutting out nine types of integrally formed lenses 70-1 to 70-9 having the same width and shifted from each other by a fixed amount from the large cylindrical Fresnel lens 72 is calculated. Then, as shown in FIG. 10B, the composite panel 74 can be designed by arranging these nine types of integrally formed lenses 70-1 to 70-9 in order and cyclically in the vertical direction. Thereby, the synthetic | combination panel 74 can be easily manufactured, without carrying out a complicated design.

  FIG. 11 shows an example of an optical path when the lenticular 25 → the condensing optical system 24 are arranged in this order from the light source side. For example, as shown in FIG. 11, when the condensing optical system 24 is arranged at the subsequent stage of the lenticular 25, the light beam expanded by each cylindrical lens of the lenticular 25 is imaged by the condensing optical system 24 (the surface at the viewpoint position). ). Here, there is a difference between the optical path length to the image plane of the light beam passing near the center of the condensing optical system 24 and the optical path length to the image surface of the light beam passing through the periphery of the condensing optical system 24. If there is a difference in the optical path length from the lenticular 25 to the image plane, a difference will occur in the magnification on the image plane of the enlarged image of each cylindrical lens of the lenticular 25.

  For example, when the viewpoint is located near the center, the optical path length to the image plane of the light beam passing near the center of the condensing optical system 24 is shorter than the optical path length to the image surface of the light flux passing through the periphery. Therefore, the magnification on the image plane of the enlarged image of the cylindrical lens near the center is smaller than the magnification on the image plane of the enlarged image of the peripheral cylindrical lens. Thus, if a magnification difference occurs in the enlarged image of the cylindrical lens of the condensing optical system 24 between the central portion and the peripheral portion, uniform light cannot be irradiated on the back surface of the display panel 20.

  FIG. 12 shows an example of an optical path in the case where the light condensing optical system 24 and the lenticular 25 are arranged in this order from the light source side. Therefore, in the display device 10 according to the present embodiment, a lenticular 25 is disposed at the rear stage of the condensing optical system 24 as shown in FIG.

  As described above, when the lenticular 25 is arranged at the rear stage of the condensing optical system 24, a difference occurs in the incident angle between the vicinity of the center of the lenticular 25 and the peripheral edge. Specifically, the light beam incident on the cylindrical lens at the center of the lenticular 25 has a small incident angle, and the light beam incident on the cylindrical lens at the periphery of the lenticular 25 has a large incident angle.

  The cylindrical lens has a smaller apparent magnification as the incident angle increases due to the characteristics of the lens. Therefore, when the lenticular 25 is arranged at the rear stage of the condensing optical system 24, the apparent magnification of the cylindrical lens around the lenticular 25 is larger than the apparent magnification of the cylindrical lens at the center of the lenticular 25. Becomes smaller. As a result, the magnification on the image plane of the magnified image of the cylindrical lens near the center and the magnification on the image plane of the magnified image of the peripheral cylindrical lens become nearly uniform.

  Therefore, according to the display device 10, uniform light can be applied to the back surface of the display panel 20. Thereby, according to the display apparatus 10, a clear image can be shown to an observer.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Display apparatus, 20 Display panel, 21 Projector part, 22 Irradiation optical system, 23 Prism panel, 24 Condensing optical system, 25 Lenticular, 26 Vertical diffusing part, 31 Right eye projector, 32 Left eye projector, 33 Beam Splitter, 34 front cylindrical lens, 35 rear cylindrical lens, 40 light source pattern, 41 right eye light source image, 42 left eye light source image, 51 refractive optical system, 52 prism, 55 first vertical diffusing plate, 56 th 2 Vertical diffuser plate, 70 Integrated lens, 72 Large cylindrical Fresnel lens, 74 Composite panel

Claims (10)

A display device that displays an image toward an observer's viewpoint,
A backlight unit that emits parallel light;
A refractive optical system having a plurality of prisms arranged in a horizontal direction and refracting light from the backlight unit in the horizontal direction so as to go in the observation direction;
A condensing optical system that condenses the light transmitted through the refractive optical system on the viewpoint of the observer;
A display panel that transmits light from the condensing optical system and displays an image;
With
The plurality of prisms have a gentler refraction angle in a region far from the optical axis than in a region near the optical axis. The display device according to claim 1, further comprising a lenticular lens that separates light from the condensing optical system into a plurality of light beams corresponding to a plurality of viewpoints. The display device according to claim 2, wherein the condensing optical system condenses the light transmitted through the refractive optical system on an observer's viewpoint. The display device is a display device that displays an image by refracting light in each of a plurality of different observation directions in the horizontal direction,
A plurality of refractive optical systems that are provided corresponding to each of the plurality of observation directions and refract light from the backlight unit in the corresponding observation directions;
The display device according to claim 1, wherein the plurality of refractive optical systems are arranged side by side in a vertical direction. The display device according to claim 4, wherein the condensing optical system is a cylindrical Fresnel lens that condenses light in a horizontal direction. The display device according to claim 5, wherein the refractive optical system and the cylindrical Fresnel lens are integrally formed. The integrally formed lens in which the refractive optical system and the cylindrical Fresnel lens are integrally formed is formed by cutting out a partial region of a large cylindrical Fresnel lens having a focal length that matches a distance to a viewpoint. Display device. A vertical diffusion unit that transmits light from the refractive optical system and diffuses the light in the vertical direction;
The vertical diffusion part is
A first vertical diffuser;
A second vertical diffusion plate disposed at a distance from the first vertical diffusion plate by a distance equal to or longer than a distance at which at least some of the adjacent light spots formed by the first vertical diffusion plate are overlapped with each other. When,
The display device according to claim 4, comprising: The backlight unit is
A projector unit that projects light onto a predetermined range;
An irradiation optical system that collects the light projected from the projector unit and outputs parallel light; and
The display device according to claim 1, comprising: The irradiation optical system is
A pre-stage cylindrical Fresnel lens that condenses light from the projector unit in a first direction;
The display device according to claim 9, further comprising: a rear-stage cylindrical Fresnel lens that condenses light transmitted through the front-stage cylindrical Fresnel lens in a direction that is 90 degrees different from the first direction.

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