Display device

Abstract

The invention provides a display device which is small in size and capable of displaying an aerial image with a wide field angle. This aerial image display device (100) is provided with: a display light source (110) provided with an emission surface for emitting an image; a beam splitter (130) disposed so as to face the emission surface of the display light source (110) in parallel; and a pair of retro-reflectors (120-1, 120-2) disposed between the display light source (110) and the beam splitter (130), the pair of retro-reflectors (120-1, 120-2) being disposed so as to be inclined outward with respect to the normal line of the emission surface.

Description

Technical Field

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

[0002] There is known aerial display using retroreflection (Aerial Imaging by Retro-Reflection: AIRR). 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 relatively large angle.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-47438 Summary of the Invention

[0006] In the display device of the AIRR method, users often view the aerial image not only from the front but also from the side. Therefore, an enlarged viewing angle is required. Figure 1 It is a diagram showing an optical system of a display device with a wide viewing angle. In the figure, solid lines represent incident light, and dashed lines represent retroreflected light.

[0007] As shown in this figure, the display device 10 includes a display light source 20, a beam splitter 30, and a retroreflective member 40. The beam splitter 30 is disposed obliquely in a shape of the Chinese character "ハ" with respect to the display light source 20. A part of the light emitted from the display light source 20 is reflected by the beam splitter 30, and the reflected light is reflected by the retroreflective member 40 in the same direction as the incident light. The retroreflected light transmits through the beam splitter 30, and an aerial image P is displayed above it. The aerial image P is formed at a position symmetric to the display 20 with respect to the plane of the beam splitter 30.

[0008] The viewing angle θ at which the user U can observe the aerial image P is limited to the range in which the retroreflective member 40 can be observed via the beam splitter 30 from the viewing point. In the conventional display device, if one wants to increase the viewing angle θ of the aerial image P, there is a technical problem that the size of the optical system must be increased, and this technical problem is more significant in the case of a display using a display such as an LCD as the light source.

[0009] An object of the present invention is to solve such a conventional technical problem and provide a small-sized display device capable of displaying an aerial image with a wide viewing angle.

[0010] The display device of the present invention can display a virtual image in the air by using retroreflection. The display device includes: a light source having an emission surface for emitting an image; an optical component that separates incident light into reflected light and transmitted light and is arranged such that its main surface faces the emission surface of the light source in parallel; and a pair of retroreflective members arranged in a region including at least the space between the light source and the optical component, and the pair of retroreflective members are arranged to be inclined outward with respect to the normal line of the emission surface.

[0011] In one mode, the optical component has a rectangular shape larger than the emission surface, the pair of retroreflective members have a rectangular shape, one retroreflective member is arranged between one end of the emission surface and one end of the optical component, and the other retroreflective member is arranged between the other end of the emission surface and the other end of the optical component. In one mode, the pair of retroreflective members have curved retroreflective surfaces. In one mode, the pair of retroreflective members are respectively inclined at an angle corresponding to the viewing position of the user. In one mode, the ends of the pair of retroreflective members are bent in the vertical direction according to the size of the optical component. In one mode, the optical component is a semi-transmissive semi-reflective mirror, a beam splitter, or a polarization beam splitter. In one mode, the display device is arranged in the vehicle interior space between the driver's seat and the front passenger seat.

[0012] Advantages of the Invention

[0013] According to the present invention, by providing a pair of inclined retroreflective members in a region including at least the space between the light source and the optical component, it is possible to expand the viewing angle of the virtual image in the air while making the optical system thin. Description of the Drawings

[0014] Figure 1 is a schematic diagram showing the schematic structure of a conventional display device.

[0015] Figure 2 is a view showing the structure of the display device according to an embodiment of the present invention, Figure 2 (A) of which is a front view, Figure 2 (B) of which is a perspective view, Figure 2 and (C) of which is a top view.

[0016] Figure 3A is a top view showing the optical path of the virtual image in the display device of the present embodiment.

[0017] Figure 3B is a front view showing the optical path of the virtual image in the display device of the present embodiment.

[0018] Figure 3C is a side view showing the optical path of the virtual image in the display device of the present embodiment.

[0019] Figure 4 This is a diagram showing a modified example of the display device of this embodiment.

[0020] Figure 5 This is a diagram showing another modified example of the display device of this embodiment.

[0021] Figure 6 This is a diagram showing an application example of the display device of an embodiment of the present invention. Detailed Description of the Invention

[0022] The display device of the present invention displays an aerial image or an aerial image using retroreflection in a three-dimensional space that can be visually confirmed without wearing special glasses or the like. It should be noted that the drawings referred to in the following description of the embodiments include displays exaggerated for easy understanding of the invention and do not directly represent the actual shape and ratio of the product as it is.

[0023] [Embodiment]

[0024] Next, embodiments of the present invention will be described in detail. Figure 2 This is a diagram showing the structure of the display device of an embodiment of the present invention. Figure 2 (A) of this is a front view thereof. Figure 2 (B) of this is a perspective view thereof. Figure 2 (C) of this is a top view thereof.

[0025] The display device 100 of this embodiment is configured to include a light source 110, a pair of retroreflective members 120-1 and 120-2, and a beam splitter 130. Although not shown here, these components can be mounted on a frame, a housing, etc., for example.

[0026] The light source 110 only needs to have a function of emitting an image or a picture, and is not particularly limited. For example, it is a display light source such as a liquid crystal display device, an organic EL display device, a projection display device, etc. 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 for example, it can be Figure 2 the screen of a smartphone as shown in (A) of this, and in addition, it can also be the screen of a portable terminal, the screen of a personal computer, the screen of a projector, etc.

[0027] The beam splitter 130 is an optical component that separates incident light into transmitted light and reflected light. For example, a semi-transmissive and semi-reflective mirror is used, or a polarization beam splitter is used in the case of light after polarization is used. The beam splitter 130 illustrated here is composed of a rectangular sheet or thin plate larger than the light-emitting surface of the light source 110. That is, the lengths in the length direction and width direction of the beam splitter 130 are larger than the lengths in the length direction and width direction of the light-emitting surface, and it is arranged such that its main surface is horizontally opposed to the light-emitting surface of the light source 110. The distance between the beam splitter 130 and the light-emitting surface is appropriately determined according to the size and tilt angle of the retroreflective members 120-1 and 120-2 arranged in at least the region of the space therebetween.

[0028] The pair of retroreflective members 120-1 and 120-2 are optical components 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-angle corner-type retroreflective elements, and bead-type retroreflective elements. The pair of retroreflective members 120-1 and 120-2 illustrated here are composed of rectangular sheets or thin plates of the same size and are arranged in at least the region of the space between the light source 110 and the beam splitter 130. That is, the inner ends of the retroreflective members 120-1 and 120-2 can protrude to the inner side beyond the light source 110 when viewed from the user's viewing point, and the front ends of the retroreflective members 120-1 and 120-2 can also protrude to the front of the beam splitter 130 when viewed from the user's viewing point.

[0029] More specifically, as shown in (C) of Figure 2 , one retroreflective member 120-1 is arranged to match one end 110A of the light-emitting surface of the light source 110 and one end 130A of the beam splitter 130, and is tilted at an angle θA with respect to the normal line (optical axis) of the light-emitting surface. The other retroreflective member 120-2 is arranged to match the other end 110B of the light-emitting surface of the light source 110 and the other end 130B of the beam splitter 130, and is tilted at an angle θB with respect to the normal line (optical axis) of the light-emitting surface. As will be described later, the angles θA and θB are determined according to the viewing point position of the user. If the viewing point positions of the left and right users are symmetric with respect to the display device 100, it is also possible to set θA = θB and arrange the pair of retroreflective members 120-1 and 120-2 symmetrically with respect to the optical axis 110. In this case, the aspect ratio of the beam splitter 130 can be the same as the aspect ratio of the light-emitting surface, or the aspect ratios can also be different.

[0030] Next, the operation of the display device of this embodiment will be described. Figures 3A to 3C It is an optical path diagram when displaying a virtual image, Figure 3A It is a top view thereof, Figure 3B It is a front view thereof, Figure 3Cis a side view thereof. In addition, the retroreflective members 120-1 and 120-2 are inclined outward at an angle θA = θB.

[0031] The light (image) emitted from the light source 110 toward the normal direction (optical axis) from the emission surface is incident on the beam splitter 130. Here, a part of the incident light is reflected, and the reflected light is reflected by the retroreflective members 120-1 and 120-2 in the same direction as the incident light. The retroreflected light passes through the beam splitter 130, and the light after passing through forms an image to generate an 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.

[0032] As Figure 3A shown, the retroreflective member 120-2 is arranged at an inclination angle θB. The user U1 on the left side in the direction of its retroreflection can observe the retroreflective member 120-2 from the viewpoint through the beam splitter 130, so that the aerial image P can be visually confirmed in the line-of-sight direction. Similarly, the retroreflective member 120-1 is arranged at an inclination angle θA. The user U2 on the right side in the direction of its retroreflection can observe the retroreflective member 120-1 from the viewpoint through the beam splitter 130, so that the aerial image P can be visually confirmed in the line-of-sight direction. In addition, from the front position at the center of the viewpoints of the left user U1 and the right user U2, the retroreflective members 120-1 and 120-2 cannot be observed or are difficult to observe through the beam splitter 130, so the aerial image P cannot be visually confirmed or is difficult to visually confirm.

[0033] In this way, according to the present embodiment, by arranging the beam splitter 130 in parallel with the light source 110 and arranging a pair of retroreflective members 120-1 and 120-2 inclined outward in a region including at least the space between the light source 110 and the beam splitter 130, a thin optical system can be realized and the viewing angle of the aerial image can be enlarged.

[0034] As a certain mode of the present embodiment, when the light emitted from the light source 110 is polarized light (such as an image of a liquid crystal display device, etc.), a λ / 4 film can be provided on the surfaces of the retroreflective sheets 120-1 and 120-2 as a retardation film, and the beam splitter 130 uses a polarization beam splitter. The polarization beam splitter transmits a part of the light in a certain polarization state and reflects the remaining part. 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 that the polarization direction of the light source 110 is substantially orthogonal to the polarization direction of the polarization beam splitter.

[0035] In addition, in the above-described embodiments, in order to expand the viewing angle in the left-right direction of the aerial image, a pair of retroreflective members 120-1 and 120-2 are respectively arranged on the left and right of the light source 110. However, in the case of expanding the viewing angle in the up-down direction of the aerial image, the pair of retroreflective members can be respectively arranged above and below the light source.

[0036] Next, a modified example of the display device of the present embodiment will be described. Figure 4 is a top view of the modified display device 100A. In the previous embodiment, the retroreflective surfaces of the retroreflective members 120-1 and 120-2 are flat surfaces. However, in the modified display device 100A, the retroreflective members 120A-1 and 120A-2 have curved surfaces or spherical surfaces with fan-shaped curved retroreflective surfaces. The curvature or the center of curvature of the retroreflective members 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 retroreflective members with a curved surface shape, the viewing angle can be further expanded compared with the case of using retroreflective members with a flat surface shape.

[0037] Figure 5 (A) of is a front view of another modified display device 100B, Figure 5 (B) of is a perspective view of another modified display device 100B. As Figure 2 shown, the length L2 of the pair of retroreflective members 120-1 and 120-2 is made longer than the length L1 of the beam splitter 130, and the protruding lower end portion W can be used when observing the aerial image from a certain viewpoint. On the other hand, in order to miniaturize the optical system, sometimes it is desired that the length L1 of the beam splitter 130 is substantially equal to the length L2 of the pair of retroreflective members 120-1 and 120-2. However, when using existing mass-produced components, it is sometimes not easy to make the length L1 of the beam splitter 130 equal to the length L2 of the retroreflective sheets 120-1 and 120-2 (L2 > L1).

[0038] In this case, the upper end portions of the retroreflective members 120-1 and 120-2 are aligned with the upper end portion of the beam splitter 130, and the elongated lower end portion W of the retroreflective members 120-1 and 120-2 is bent in the 90-degree direction at a position consistent with the length L1 of the beam splitter 130. The bent lower end portion W does not directly affect the display of the aerial image. On the contrary, the lower end portions of the retroreflective members 120-1 and 120-2 can also be aligned with the lower end portion of the beam splitter 130, and the upper end portions of the retroreflective members 120-1 and 120-2 can be bent. By bending the retroreflective members in this way, miniaturization of the optical system of the display device 100B can be achieved, and the manufacturing cost can be reduced.

[0039] Next, an application example of the display device of the present embodiment will be described. Figure 6(A) is a side view showing the positional relationship between the user and the display device 100. Figure 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 illustrative, and the display device of the present invention is not limited to such positional relationships.

[0040] For example, the display device 100 is arranged at a position intermediate between the users U1 and U2 and tilted upward in the direction of the user's viewing point, and the left and right retroreflective members inside are arranged to be tilted outward in the direction of the viewing points of the users U1 and U2. The left and right users U1 and U2 can visually confirm the aerial image in their respective line-of-sight directions.

[0041] Figure 6 (C) shows an example in which the display device 100 is installed in the vehicle interior space (for example, the instrument panel, instrument panel part) between the driver's seat 150 and the front passenger seat 160. The driver sitting in the driver's seat 150 and the passenger sitting in the front passenger seat 160 can visually confirm the aerial image displayed by the display device 100 from their respective line-of-sight directions. In addition, the passengers sitting in the seats behind the driver's seat 150 and the front passenger seat 160 can also visually confirm the aerial image from their respective line-of-sight directions. Moreover, when the line-of-sight direction of the passengers sitting in the rear seats is a direction of observing the display device 100 from approximately the front, the passengers in the rear seats can also visually confirm the image emitted from the light source via the beam splitter instead of visually confirming the aerial image. In this case, the beam splitter is, for example, a semi-transmissive semi-reflective mirror.

[0042] Moreover, the display device of the present embodiment can be applied not only to the vehicle interior space but also to devices and systems having uses for viewing from the left and right. For example, it can also be applied in front of the seats of a two-seater attraction vehicle, or in front of the seats of a tram, bus, aircraft, etc.

[0043] As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to specific embodiments, and various modifications and changes can be made within the scope of the gist of the invention described in the claims.

[0044] [Description of Reference Numerals]

[0045] 100, 100A, 100B: Display device

[0046] 110: Light source

[0047] 120-1, 120-2, 120A-1, 120A-2: Retroreflective member

[0048] 130: Beam splitter

[0049] 150: Driver's seat

[0050] 160: Passenger seat.

Claims

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

2. The display device according to claim 1, characterized in that The optical component has a rectangular shape larger than the emission surface, and the pair of retroreflectors have a rectangular shape, One retroreflector is arranged between one end of the emission surface and one end of the optical component, and the other retroreflector is arranged between the other end of the emission surface and the other end of the optical component.

3. The display device according to claim 1, characterized in that The pair of retroreflectors have curved retroreflective surfaces.

4. The display device according to claim 1, characterized in that The pair of retroreflectors are respectively inclined at angles corresponding to the viewing position of the user.

5. The display device according to claim 2, characterized in that The ends of the pair of retroreflectors are bent in the vertical direction according to the size of the optical component.

6. The display device according to claim 1, characterized in that The optical component is a semi-transmissive semi-reflective mirror, a beam splitter, or a polarization beam splitter.

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

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