Display device

Abstract

To provide a display device which is small and can display aerial videos with wide angles of field.SOLUTION: A display device 100 displaying aerial videos according to the present invention includes: a display light source 110 with an emission surface for emitting pictures; a beam splitter 130 arranged to face the emission surface of the display light source 110 in parallel; and a pair of retroreflection materials 120-1 and 120-2 arranged between the display light source 110 and the beam splitter 130. The pair of retroreflection materials 120-1 and 120-2 are arranged to be inclined to the outside with respect to the normal line of the emission surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a display device having a function of displaying an image in the air by using retroreflection.

Background Art

[0002] Aerial Imaging by Retro - Reflection: AIRR is known. For example, the display device of Patent Document 1 includes a first retroreflective portion disposed at a position in the emission direction of light emitted from a light source, and a light branching portion that reflects at least a part of the light transmitted through the first retroreflective portion as first reflected light and transmits at least a part of the first reflected light retroreflected by the first retroreflective portion, enabling observation of an aerial image from a wide angle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an AIRR - type display device, since a user often views an aerial image not only from the front but also from the side, it is required to widen the viewing angle. FIG. 1 is a diagram showing an optical system of a wide - viewing - angle display device. In the figure, solid lines indicate incident light, and dashed lines indicate retroreflected light.

[0005] As shown in the figure, the display device 10 includes a display light source 20, a beam splitter 30, and a retroreflective material 40. The beam splitter 30 is arranged to be inclined like a "V" with respect to the display light source 20. The light emitted from the display light source 20 is partially reflected by the beam splitter 30, and the reflected light is reflected by the retroreflective material 40 in the same direction as the incident light. The retroreflected light passes through the beam splitter 30, and a virtual image P is displayed above it. The virtual image P is formed at a position symmetric to the display 20 with respect to the plane of the beam splitter 30.

[0006] The viewing angle θ at which the user U can observe the virtual image P is limited to the range in which the retroreflective material 40 can be seen from the viewpoint through the beam splitter 30. In a conventional display device, there is a problem that if the viewing angle θ of the virtual image P is to be increased, the size of the optical system has to be increased, and this problem is more prominent when a display such as an LCD is used as the light source.

[0007] An object of the present invention is to solve such a conventional problem and provide a display device that can display a virtual image with a wide viewing angle while being small in size.

Means for Solving the Problem

[0008] The display device according to the present invention is capable of displaying a virtual image using retroreflection, and includes a light source having an emission surface for emitting an image, an optical member that separates incident light into reflected light and transmitted light, the optical member being arranged such that its main surface faces the emission surface of the light source in parallel, and a pair of retroreflective materials arranged in a region including at least the space between the light source and the optical member. The pair of retroreflective materials are arranged to be inclined outward with respect to the normal of the emission surface.

[0009] In one aspect, the optical member has a rectangular shape larger than the exit surface, the pair of retroreflective materials have a rectangular shape, and one of the retroreflective materials is disposed between one end of the exit surface and one end of the optical member, and the other retroreflective material is disposed between the other end of the exit surface and the other end of the optical member. In one aspect, the pair of retroreflective materials have a curved retroreflective surface. In one aspect, each of the pair of retroreflective materials is tilted at an angle according to the viewpoint position of the user. In one aspect, the ends of the pair of retroreflective materials are bent in the vertical direction according to the size of the optical member. In one aspect, the optical member is a half mirror, a beam splitter, or a polarizing beam splitter. In one aspect, the display device is disposed in the vehicle interior space between the driver's seat and the passenger seat.

Effect of the Invention

[0010] According to the present invention, by providing a pair of inclined retroreflective materials in a region including at least the space between the light source and the optical member, it is possible to widen the viewing angle of the aerial image while making the optical system thinner.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] The display device according to the present invention displays a retroreflective aerial image or aerial image using a three-dimensional space that can be visually recognized without wearing special glasses or the like. It should be noted that the drawings referred to in the following description of the embodiments include exaggerated displays for ease of understanding of the invention, and do not represent the actual shape and scale of the product as it is.

Embodiment

[0013] Next, embodiments of the present invention will be described in detail. FIG. 2 is a diagram showing the configuration of the display device according to an embodiment of the present invention, FIG. 2(A) is a front view thereof, FIG. 2(B) is a perspective view thereof, and FIG. 2(C) is a top view thereof.

[0014] The display device 100 of the present embodiment includes a light source 110, a pair of retroreflective materials 120-1 and 120-2, and a beam splitter 130. Although these members are not shown here, they can be attached to, for example, a housing or a casing.

[0015] The light source 110 is not particularly limited as long as it has a function of emitting an image or a picture. For example, it is a display light source such as a liquid crystal display device, an organic EL display device, or a projection display device. The display light source has, for example, a rectangular emission surface and emits an image in the normal direction (optical axis direction) of the emission surface. Such a display light source is not particularly limited, and may be, for example, the screen of a smartphone as shown in FIG. 2(A), or other screens of portable terminals, personal computers, projectors, etc.

[0016] The beam splitter 130 is an optical member that separates incident light into transmitted light and reflected light. For example, a half mirror or a polarizing beam splitter is used when polarized light is used. The beam splitter 130 exemplified here is composed of a rectangular sheet or thin plate larger than the emission surface of the light source 110. That is, the lengths of the beam splitter 130 in the longitudinal and transverse directions are larger than the lengths of the emission surface in the longitudinal and transverse directions, and its main surface is arranged to face horizontally the emission surface of the light source 110. The distance between the beam splitter 130 and the emission surface is appropriately determined according to the sizes and tilt angles of the retroreflective materials 120-1 and 120-2 arranged in the region including at least the space therebetween.

[0017] The pair of retroreflective materials 120-1 and 120-2 are optical members that reflect light in the same direction as the incident light. For example, they are composed of prism-type retroreflective elements such as triangular pyramid-type retroreflective elements and full cube corner-type retroreflective elements, or bead-type retroreflective elements. The pair of retroreflective materials 120-1 and 120-2 exemplified here are composed of rectangular sheets or thin plates of the same size and are arranged in the region including at least the space between the light source 110 and the beam splitter 130. That is, the rear ends of the retroreflective materials 120-1 and 120-2 may protrude deeper than the light source 110 when viewed from the user's viewpoint, or the front ends of the retroreflective materials 120-1 and 120-2 may protrude in front of the beam splitter 130 when viewed from the user's viewpoint.

[0018] More specifically, as shown in Fig. 2(C), one of the retroreflective materials 120-1 is aligned with one end 110A of the emission surface of the light source 110 and one end 130A of the beam splitter 130, and is arranged to be inclined at an angle θA with respect to the normal (optical axis) of the emission surface. The other retroreflective material 120-2 is arranged to be aligned with the other end 110B of the emission surface of the light source 110 and the other end 130B of the beam splitter 130, and is inclined at an angle θB with respect to the normal (optical axis) of the emission surface. As will be described later, the angles θA and θB are determined according to the viewpoint position of the user. If the viewpoint positions of the left and right users are symmetric with respect to the display device 100, θA = θB, and the pair of retroreflective materials 120-1 and 120-2 may be arranged symmetrically with respect to the optical axis 110. In this case, the aspect ratio of the beam splitter 130 may be the same as that of the emission surface, or the aspect ratios may be different.

[0019] Next, the operation of the display device of this embodiment will be described. Fig. 3 is an optical path diagram when the aerial image is displayed. Fig. 3A is a top view thereof, Fig. 3B is a front view thereof, and Fig. 3C is a side view thereof. It is assumed that the retroreflective materials 120-1 and 120-2 are inclined outward at an angle θA = θB.

[0020] The light (image) emitted from the emission surface of the light source 110 in the direction of the normal (optical axis) enters the beam splitter 130. Part of the incident light is reflected there, and the reflected light is reflected by the retroreflective materials 120-1 and 120-2 in the same direction as the incident light. The retroreflected light passes through the beam splitter 130, and the transmitted light forms an image to generate the aerial image P. The aerial image P is generated at a position symmetric to the light source 110 with respect to the surface of the beam splitter 130.

[0021] As shown in Fig. 3A, the retroreflective material 120-2 is arranged at an inclination angle θB. Since the left user U1 located in the retroreflecting direction can observe the retroreflective material 120-2 through the beam splitter 130 from the viewpoint, the aerial image P can be visually recognized in the line-of-sight direction. Similarly, the retroreflective material 120-1 is arranged at an inclination angle θA. Since the right user U2 located in the retroreflecting direction can observe the retroreflective material 120-1 through the beam splitter 130 from the viewpoint, the aerial image P can be visually recognized in the line-of-sight direction. Note that from the front position at the center of the viewpoints of the left user U1 and the right user U2, it is impossible or difficult to observe the retroreflective materials 120-1 and 120-2 through the beam splitter 130, so it is impossible or difficult to visually recognize the aerial image P.

[0022] Thus, according to this embodiment, by arranging the beam splitter 130 parallel to the light source 110 and arranging a pair of retroreflective materials 120-1 and 120-2 that are inclined outward in a region including at least the space between the light source 110 and the beam splitter 130, it is possible to widen the viewing angle of the aerial image while realizing a thin optical system.

[0023] In a certain aspect of this embodiment, when the light emitted from the light source 110 is polarized light (for example, the image of a liquid crystal display device, etc.), a λ / 4 film, for example, may be provided as a retardation film on the surfaces of the retroreflective sheets 120-1 and 120-2, and a polarization beam splitter may be used for the beam splitter 130. The polarization beam splitter transmits a part of the light in a certain polarization state and reflects the rest. The polarization direction of the polarization beam splitter is determined in relation to the polarization direction of the light emitted from the light source 110. For example, it is determined such that the polarization direction of the light source 110 is substantially orthogonal to the polarization direction of the polarization beam splitter.

[0024] In the above embodiment, a pair of retroreflective materials 120-1 and 120-2 are arranged on the left and right sides of the light source 110 to widen the viewing angle in the left-right direction of the aerial image. However, when widening the viewing angle in the up-down direction of the aerial image, a pair of retroreflective materials can be arranged above and below the light source, respectively.

[0025] Next, a modified example of the display device of this embodiment will be described. FIG. 4 is a top view of the display device 100A of the modified example. In the previous embodiment, the retroreflective surfaces of the retroreflective materials 120-1 and 120-2 were flat. However, in the display device 100A of the modified example, the retroreflective materials 120A-1 and 120A-2 have a curved surface or a spherical surface with a fan-shaped curvature for the retroreflective surface. The curvature or the center of curvature of the retroreflective materials 120A-1 and 120A-2 is appropriately determined according to the positions of the left and right user viewpoints U1 and U2. By using such a retroreflective material with a curved surface shape, the viewing angle can be widened more than when using a retroreflective material with a flat shape.

[0026] FIG. 5(A) is a front view of a display device 100B of another modified example, and FIG. 5(B) is a perspective view of the display device 100B of another modified example. As shown in FIG. 2, it is possible to make the length L2 of the pair of retroreflective materials 120-1 and 120-2 longer than the length L1 of the beam splitter 130 and use the protruding lower end portion W when viewing the aerial image from a certain viewpoint. On the other hand, in order to miniaturize the optical system, it may be desirable to make the length L1 of the beam splitter 130 and the lengths L2 of the pair of retroreflective materials 120-1 and 120-2 substantially equal. However, when using existing mass-produced parts, it may not be easy to make the length L1 of the beam splitter 130 and the lengths L2 of the retroreflective sheets 120-1 and 120-2 equal (L2>L1).

[0027] In such a case, align the upper ends of the retroreflective materials 120-1 and 120-2 with the upper end of the beam splitter 130, and bend the elongated lower ends W of the retroreflective materials 120-1 and 120-2 at a position matching the length L1 of the beam splitter 130 by 90 degrees. The bent lower ends W do not directly affect the display of the aerial image. On the contrary, the lower ends of the retroreflective materials 120-1 and 120-2 may be aligned with the lower end of the beam splitter 130, and the upper ends of the retroreflective materials 120-1 and 120-2 may be bent. By bending the retroreflective materials in this way, the miniaturization of the optical system of the display device 100B can be achieved, and the manufacturing cost can be reduced.

[0028] Next, an application example of the display device of this embodiment will be described. Fig. 6(A) is a side view showing the positional relationship between the user and the display device 100, and Fig. 6(B) is a front view showing the positional relationship between the user and the display device 100. It should be noted that these positional relationships are merely examples, and the display device of the present invention is not limited to such positional relationships.

[0029] For example, the display device 100 is arranged at an intermediate position between the user U1 and the user U2 and is inclined upward so as to face the viewing direction of the user. The internal left and right retroreflective materials are inclined outward so as to face the viewing directions of the users U1 and U2. The left and right users U1 and U2 can visually recognize the aerial image in their respective line-of-sight directions.

[0030] FIG. 6(C) shows an example in which the display device 100 is attached to the interior space (for example, the dashboard or the instrument panel portion) between the driver's seat 150 and the passenger seat 160. The driver sitting on the driver's seat 150 and the passenger sitting on the passenger seat 160 can visually recognize the aerial image displayed by the display device 100 from their respective line-of-sight directions. Also, the passengers sitting on the seats behind the driver's seat 150 and the passenger seat 160 can also visually recognize the aerial image from their respective line-of-sight directions. Further, when the line-of-sight direction of the passenger sitting on the rear seat is generally in the direction of viewing the display device 100 from the front, the passenger on the rear seat can also visually recognize, not the aerial image, but the image emitted from the light source via the beam splitter. In this case, the beam splitter is, for example, a half mirror.

[0031] Furthermore, the display device of the present embodiment can also be applied to devices and systems that are used for viewing from the left and right in addition to the interior space. For example, it can be applied in front of the seats of a two-seater attraction, or in front of the seats of a train, a bus, an aircraft, etc.

[0032] As described above in detail with respect to the preferred embodiments of the present invention, the present invention is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the gist of the invention described in the claims.

Explanation of Reference Numerals

[0033] 100, 100A, 100B: Display device 110: Light source 120-1, 120-2, 120A-1, 120A-2: Retroreflective material 130: Beam splitter 150: Driver's seat 160: Passenger seat

Claims

1. A display device capable of displaying an aerial image using retroreflection, comprising: a light source having an emission surface for emitting an image; an optical member that separates incident light into reflected light and transmitted light, the optical member being arranged such that its main surface faces the emission surface of the light source in parallel; a pair of retroreflective materials arranged in a region including at least the space between the light source and the optical member; The pair of retroreflective materials is arranged to be inclined outward with respect to the normal of the emission surface. The display device.

2. The optical member has a rectangular shape larger than the emission surface, and the pair of retroreflective materials has a rectangular shape. One of the pair of retroreflective materials is arranged between one end of the emission surface and one end of the optical member, and the other retroreflective material is arranged between the other end of the emission surface and the other end of the optical member. The display device according to claim 1.

3. The pair of retroreflective materials has a curved retroreflective surface. The display device according to claim 1.

4. Each of the pair of retroreflective materials is inclined at an angle corresponding to the viewpoint position of the user. The display device according to claim 1.

5. The ends of the pair of retroreflective materials are bent vertically according to the size of the optical member. The display device according to claim 2.

6. The optical member is a half mirror, a beam splitter, or a polarizing beam splitter. The display device according to claim 1.

7. The display device is arranged in the interior space between the driver's seat and the passenger seat. The display device according to claim 1.

Images