Space floating image display device and retroreflective member used therein

Abstract

To suitably display a video to the outside of a space, which contributes to "3 Good Health and Well-Being," "9 Industry, Innovation and Infrastructure" and "11 Sustainable Cities and Communities" of Sustainable Development Goals.SOLUTION: A space floating video information display system comprises: a display panel that displays a video; a light source device for the display panel; and a retroreflective member that reflects video light from the display panel and causes a space floating video of a real image to be displayed in a space with the reflected light. Technical means and structure preventing entry of moisture or the like from end faces of laminated reflecting surfaces of the retroreflective member are provided to provide the retroreflective member with excellent environmental resistance performance.SELECTED DRAWING: Figure 36

Description

[Technical Field]

[0001] The present invention provides Space-floating image display device The present invention also relates to a retroreflective member used therefor. [Background technology]

[0002] For example, Patent Document 1 discloses a retroreflective optical member used in an image display device that displays images in space in a space floating information display system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-128722 Summary of the Invention [Problem to be solved by the invention]

[0004] In retroreflective optical elements of the prior art, after reflective surfaces are laminated and each reflective surface is adhesively fixed, changes in the temperature and humidity of the surrounding environment can allow liquids such as moisture to penetrate from the edge of the bonded surface, causing the bonded surface to separate and creating an interface, which not only significantly reduces the retroreflective properties but also causes external light to be reflected at the interface when an observer directly observes the retroreflective element, significantly reducing the image quality of the floating image in space. Furthermore, reflection at the interface makes it appear as if the ordinary glass material has cracked, and the floating information display system has malfunctioned, but conventional retroreflective elements do not take into consideration the technical means or structure to prevent moisture and other liquids from penetrating from the edge of the bonded portion.

[0005] The object of the present invention is to provide a retroreflective member with excellent environmental resistance by providing technical means and a structure that prevents moisture and the like from entering through the laminated end faces of the reflective surfaces of the retroreflective member used in a space-floating information display system or a space-floating image display device. [Means for solving the problem]

[0006] To solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above problems, and the following provides an example of a space-floating image display device using a retroreflective optical element. The retroreflective optical element used in the space-floating image information display system as an example of the present application is formed by laminating reflective surfaces and adhesively fixing each reflective surface, and then performing a bonding process on the end faces or a post-processing to prevent the penetration of moisture, etc. into the end faces. [Effects of the Invention]

[0007] According to the present invention, a space-floating image information system with excellent environmental resistance can be realized, and in particular, by preventing the laminated and joined reflective surfaces from separating due to the intrusion of moisture or the like from the end face of the retroreflective member, the space-floating image information can be displayed in an optimal manner without degrading the image quality. Other problems, configurations, and effects will be made clear in the following description of the embodiment. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams illustrating the configuration of a retroreflective member according to an embodiment of the present invention and the position where a spatially floating image is generated. [Figure 2] 1 is an explanatory diagram for explaining the mechanism by which a ghost image is generated by an extraordinary ray generated by retroreflection according to an embodiment of the present invention. FIG. [Figure 3] 10 is an explanatory diagram for explaining the mechanism of generation of extraordinary rays generated by a retroreflective member used in another space floating image information system. FIG. [Figure 4] 1 is an explanatory diagram for explaining the mechanism for eliminating extraordinary rays that occur when external light is incident on a retroreflective member according to an embodiment of the present invention. FIG. [Figure 5] 10 is a characteristic diagram showing the optimum use conditions of the retroreflective member in the space floating image information display system according to one embodiment of the present invention. FIG. [Figure 6] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image information display system according to an embodiment of the present invention; [Figure 7]1 is a diagram showing a second embodiment of the main part configuration and retroreflection part configuration of a space floating image information display system according to an embodiment of the present invention; [Figure 8] 10 is a diagram showing a third embodiment of the main part configuration and retroreflection part configuration of the space floating image information display system according to an embodiment of the present invention. FIG. [Figure 9] 10 is a diagram showing a fourth embodiment of the main part configuration and retroreflection part configuration of the space floating image information display system according to an embodiment of the present invention; FIG. [Figure 10] 1 is an explanatory diagram for explaining the operation principle of an optical member that refracts image light used in the space floating image information display system of the present invention. [Figure 11] 1 is an explanatory diagram showing the structure and principle of a space floating image information display system using an optical element that refracts image light according to the present invention; [Figure 12] 1 is an explanatory diagram for explaining the structure of an optical member that refracts image light used in the space floating image information display system of the present invention. FIG. [Figure 13] 10 is an explanatory diagram for explaining the arrangement of an optical member and an image source used in the space floating image information display system of the present invention, which prevents a viewer from directly viewing the image displayed by the image source. FIG. [Figure 14] 4 is a cross-sectional view showing the arrangement of a member that blocks extraordinary rays generated in a retroreflecting portion according to an embodiment of the present invention. FIG. [Figure 15] 1 is a diagram showing a configuration of a main part of a first embodiment of a space floating image information display system according to an embodiment of the present invention; [Figure 16] 10A and 10B are diagrams showing the appearance and main components of a second embodiment of a space floating image information display system according to an embodiment of the present invention; [Figure 17] 10 is a diagram showing the appearance and main components of a second embodiment of another space floating image information display system according to an embodiment of the present invention; FIG. [Figure 18] 1 is an explanatory diagram for explaining a sensing means provided in a space floating image information display system according to an embodiment of the present invention; [Figure 19] FIG. 10 is a diagram showing another example of a specific configuration of a light source device of another type. [Figure 20A]FIG. 10 is a structural diagram showing another example of a specific configuration of a light source device of another type. [Figure 20B] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 20C] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 20D] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 21A] FIG. 10 is a structural diagram showing another example of a specific configuration of a light source device of another type. [Figure 21B] FIG. 10 is a diagram showing another example of a specific configuration of a light source device of another type. [Figure 22] 10 is an enlarged view showing the surface shape of a light guide diffusion portion of another example of a specific configuration of a light source device. FIG. [Figure 23] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 24] 3A and 3B are structural diagrams showing examples of specific configurations of the light source device. [Figure 25] 1A to 1C are a perspective view, a top view, and a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 26] 1A and 1B are perspective and top views showing an example of a specific configuration of a light source device. [Figure 27] 10A and 10B are explanatory diagrams for explaining the light source diffusion characteristics of the image display device. [Figure 28] 10A and 10B are explanatory diagrams for explaining the light source diffusion characteristics of the image display device. [Figure 29] FIG. 10 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 30] FIG. 10 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 31] FIG. 1 is a diagram showing a coordinate system for measuring visual characteristics of a liquid crystal panel. [Figure 32] FIG. 1 is a diagram showing the luminance angle characteristics (longitudinal direction) of a typical liquid crystal panel. [Figure 33] FIG. 1 is a diagram showing the luminance angle characteristics (short side direction) of a typical liquid crystal panel. [Figure 34]FIG. 1 is a diagram showing the angle characteristics (longitudinal direction) of contrast of a typical liquid crystal panel. [Figure 35] FIG. 1 is a diagram showing the angle characteristics (short side direction) of contrast of a typical liquid crystal panel. [Figure 36] 1A and 1B are explanatory diagrams for explaining a structure for preventing performance degradation due to moisture absorption caused by retroreflection according to one embodiment of the present invention. [Figure 37] 1 is an explanatory diagram for explaining the structure of a goods vending machine equipped with a space floating image information display system according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the contents of the embodiments described below (hereinafter also referred to as "the present disclosure"). The present invention also extends to the spirit of the invention and the scope of the technical ideas described in the claims, or equivalents thereof. Furthermore, the configurations of the embodiments (examples) described below are merely examples, and various changes and modifications may be made by those skilled in the art within the scope of the technical ideas disclosed in this specification.

[0010] Furthermore, in the drawings for explaining the present invention, components having the same or similar functions are given the same reference numerals, and different names are used as appropriate, while repeated explanations of functions, etc. may be omitted. In the following description of the embodiments, an image floating in space is expressed using the term "space-floating image." Instead of this term, it is also acceptable to express it as "aerial image," "spatial image," "floating image," "space-floating optical image of displayed image," "floating optical image of displayed image," etc. The term "space-floating image," which is mainly used in the description of the embodiments, is used as a representative example of these terms.

[0011] The present disclosure relates to an information display system that can transmit an image generated by image light from a large-area image light source through a transparent member that divides a space, such as the glass of a shop window, and display it as a floating image inside or outside a store (space). The present disclosure also relates to a retroreflective member used in such an information display system.

[0012] According to the following embodiment, for example, high-resolution video information can be displayed in a floating state on the glass surface of a shop window or a light-transmitting plate. In this case, by making the divergence angle of the emitted video light small, i.e., acute, and further aligning it with a specific polarization, it is possible to efficiently reflect only the normal reflected light from the retroreflective material. This results in high light utilization efficiency, and it is possible to suppress ghost images that occur in addition to the main floating image, which was a problem with conventional retroreflective methods, and to obtain a clear floating image in space.

[0013] Furthermore, a device including the light source of the present disclosure can provide a novel and highly usable floating image information display system that can significantly reduce power consumption. Furthermore, the technology of the present disclosure can provide a floating image information display system for a vehicle that can display a so-called unidirectional floating image that can be viewed from outside the vehicle through shield glass such as the vehicle's windshield, rear window, or side window.

[0014] On the other hand, conventional floating-image information display systems combine an organic electroluminescence (EL) panel or a liquid crystal display panel (LCD panel or display panel) as a high-resolution color display image source with a retroreflective member. The first retroreflective member 2 used in conventional floating-image display devices diffuses image light over a wide angle. Therefore, in addition to the light reflected normally by the retroreflective member of the first embodiment, which is a polyhedron as shown in FIG. 3, the shape of the retroreflective member 2a used in FIG. 3 is hexahedral, and as a result, six ghost images, including ghost images 3a and 3f, are generated by the image light incident from an oblique angle, impairing the image quality of the floating-image. Furthermore, the ghost images, which are the same floating-image as the viewer, can be viewed by people other than the viewer, posing a major security issue.

[0015] 1(A), the second retroreflective member 5 used in the space floating image display device is formed by arranging optical members 20 having a large number of band-like planar light reflecting portions at a constant pitch perpendicularly on one side surface of the first light control panel 221 and the second light control panel 222 of the transparent flat plates 18 and 17, each having a constant thickness. Here, the light reflecting portions of the optical members 20 constituting the first light control panel 221 and the second light control panel 222 are arranged to intersect (orthogonal in this embodiment) in plan view.

[0016] Next, the function of the second retroreflective member used in the space-floating image display device and a specific example of the space-floating image display device will be described. As shown in Fig. 1(B), the second retroreflective member 5 is generally disposed at an angle of 40 to 50 degrees relative to the image display device 1. In this case, the space-floating image 3 is emitted from the second retroreflective member 5 at the same angle as the angle at which the image light enters the second retroreflective member 5. In this case, the space-floating image is formed at a symmetrical position, a distance equal to the distance L1 from the image display device 1 to the second retroreflective member 5.

[0017] The mechanism of how the space-floating image is formed will be explained in detail below with reference to Figures 1 and 2. Image light emitted from the image display device 1 provided on one side of the second retroreflective member 5 is reflected by the flat light reflecting portion C (the reflecting surface of the light reflecting member 20) of the second light control member 222, and then reflected by the flat light reflecting portion C' (the reflecting surface of the light reflecting member 20) of the first light control member 221, thereby forming a space-floating image 3 (a real image) at a position outside the second retroreflective member 5 (the space on the other side). In other words, by using this second retroreflective member 5, a space-floating image information device is established, and the image of the image display device 1 can be displayed in space as a space-floating image.

[0018] As described above, the second retroreflective member 5 has two reflective surfaces, and therefore generates two ghost images 3a and 3b in accordance with the number of reflective surfaces in addition to the spatially floating image 3, as shown in Figures 2(A) and 2(B).

[0019] Furthermore, it was found that when the intensity of external light is high and it enters from the top surface of the second retroreflective member 5, the spacing between the reflective surfaces (300 μm or less) becomes short, causing optical interference, resulting in the observation of rainbow-colored reflected light, which could lead to the observer's awareness of the presence of the retroreflective member. Therefore, to prevent the interference light generated by the pitch of the reflective surfaces of the retroreflective member 5 due to the incidence of external light from returning to the observer, the area where the interference light occurs was experimentally determined using the measurement environment shown in Figure 4, with the angle of incidence of the external light as a parameter. The results obtained are shown in Figure 5. It was found that when the pitch of the reflective surfaces is 300 μm and the height of the reflective surfaces is 300 μm, the interference light does not return to the observer if the inclination angle θYZ of the retroreflective member is 35 degrees or more.

[0020] On the other hand, it was found that with the ratio (H / P) of the pitch P of the light-reflecting member 20 to the height H of the reflective surface described above, approximately 60% of the reflective surface forms a space-floating image due to retroreflection, while the remaining 40% becomes abnormally reflected light that generates ghost images. In order to improve the resolution of space-floating images in the future, it will be necessary to shorten the pitch of the reflective surface. Additionally, to suppress the generation of ghost images, the height of the reflective surface must be made higher than it is currently. However, due to manufacturing constraints on the second retroreflective member 5, it is best to select the ratio (H / P) of the reflective surface pitch P to the height H from the current 1.0 in the range of 0.8 to 1.2.

[0021] As a result of the above-mentioned investigations, the inventors have investigated a retroreflective optical system that realizes high quality of the space-floating image obtained in a space-floating image information display system using a second retroreflective member that, in principle, generates a small amount of ghost images, and have arrived at the present invention. The present invention will be described in detail below with reference to the drawings.

[0022] <Configuration example of the first retroreflection optical system forming the space floating image information display system> FIG. 6 is a diagram showing an example of the configuration of a retro-optical system used to realize the space-floating image information display system of the present disclosure. FIG. 6 is also a diagram illustrating the overall configuration of the space-floating image information display system of the present disclosure. Referring to FIG. 6, for example, according to the space-floating image information display system of the present disclosure (hereinafter also referred to as "the present system"), when the space-floating image information display system is placed on a desk, a monitor of the space-floating image will view the space-floating image from below at an angle θ6. It has been discovered that the optimal position for monitoring the space-floating image is to arrange the image display device 1 so that the sum (θ2 + θ1) of the angle θ2 between the display surface of the image display device 1 and the retroreflective member 5 and the angle θ1 between the retroreflective member 5 and the space-floating image are approximately equal.

[0023] As described above, the floating image is formed symmetrically to the image display device 1 with respect to the second retroreflective member 5, so the angles θ1 and θ2 formed by their respective arrangements are equal. Therefore, once the angle θ6 at which the observer looks into the floating image display system is determined, it is advisable to arrange the image display device 1 and the second retroreflective member 5 in the retroreflective optical system so that the angle θ2 = θ6 / 2. Furthermore, a predetermined distance L1 is required between the image display device 1 and the second retroreflective member 5 to improve the cooling efficiency of the image display device 1. Furthermore, in order to structurally obtain the angle θ2 described above, it is necessary to determine the distance L2 relative to L1.

[0024] The configuration of the space-floating image information display system of the present disclosure will be described in more detail. As shown in Fig. 6, the system includes an image display device 1 that diverges image light of a specific polarized wave at a narrow angle, and a second retroreflective member 5. The image display device 1 includes a liquid crystal display panel (hereinafter sometimes simply referred to as a liquid crystal panel) 11, and a light source device 13 that generates light of a specific polarized wave having narrow-angle diffusion characteristics.

[0025] The image light of a specific polarization from the image display device 1 is selectively transmitted through an absorption polarizing sheet 101 with an anti-reflection film on the surface of the second retroreflective member 5 that faces the outside of the device (not shown), and the other polarized wave contained in the external light is absorbed, thereby preventing the influence of the reflected light from the surface of the second retroreflective member 5 on the spatially floating image obtained.

[0026] Here, the absorptive polarizing sheet 101, which selectively transmits image light of a specific polarization, has the property of transmitting image light of a specific polarization, so the image light of a specific polarization passes through the absorptive polarizing sheet 101. The transmitted image light forms a floating image 3 in a position symmetrical to the retroreflective member 5.

[0027] The light that forms the floating image 3 is a collection of light rays that converge from the retroreflective member 5 onto the optical image of the floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is an image with high directionality, unlike the diffused image light formed on a screen by a general projector or the like.

[0028] 6, the levitating image 3 will appear as a bright image when viewed by a user from the direction shown in the figure, but when viewed by other people from above, below, or in front of or behind the page, the levitating image 3 will not appear as an image at all. This characteristic is extremely suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0029] Depending on the performance of the retroreflective member 5, the polarization axis of the reflected image light may become misaligned. In this case, a portion of the image light with a misaligned polarization axis is absorbed by the above-mentioned absorptive polarizing sheet 101. This prevents unnecessary reflected light from being generated in the retroreflective optical system, and can prevent or suppress degradation in the image quality of the spatially floating image.

[0030] Furthermore, in the space-floating image display device using the retroreflective optical system of the present disclosure, even when an observer looks into the space-floating image, the display screen of the image display device 1 is shielded from light by the reflective surface of the retroreflective member 5. Therefore, in this space-floating image display device, the image displayed by the image display device 1 is more difficult to see directly than when the image display device 1 and the retroreflective member are directly opposite each other.

[0031] <Configuration example of the second retroreflection optical system forming the space floating image information display system> FIG. 7 is a diagram showing the main components of another example of a retro-optical system for realizing a space-floating image information display system according to an embodiment of the present invention. This space-floating image information display system is suitable for an observer to observe a space-floating image from diagonally above. The image display device 1 comprises a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with a narrow-angle diffusion characteristic. The liquid crystal display panel 11 may be a small liquid crystal display panel with a screen size ranging from about 5 inches to a large liquid crystal display panel exceeding 80 inches. The image light from the liquid crystal display panel 11 is emitted toward a retroreflective member (retroreflective portion or retroreflective plate) 5.

[0032] Light from a narrow-divergence light source device 13 (described later) is incident on the liquid crystal panel 11, generating a narrow-divergence image light beam that is then incident on the retroreflective member 5 to produce a floating image 3. The floating image 3 is formed at a symmetrical position on the image display device 1, with the retroreflective member 5 as the plane of symmetry. To eliminate ghost images and produce a high-quality floating image 3, an image light control sheet 334, the structure of which is shown in FIG. 12(A), can be provided on the exit side of the liquid crystal panel 11 to control the diffusion characteristics in unwanted directions. Furthermore, since the reflectivity of the image light from the liquid crystal panel 11 can be increased by a reflective member such as a retroreflective member, it is preferable to use S-polarized light. However, if the observer wears polarized sunglasses, the floating image will be reflected or absorbed by the polarized sunglasses. To address this issue, a depolarizing element 339 can be provided to optically convert a portion of the image light of a specific polarization into the other polarization, thereby simulating natural light. This allows observers to observe a good floating image even when wearing polarized sunglasses. When these are optically joined by adhesive 338, no light reflecting surface is generated, and the image quality of the floating image in space is not impaired.

[0033] Commercially available depolarizing elements include Cosmoshine SRF (manufactured by Toyobo Co., Ltd.) and depolarizing adhesive (manufactured by Nagase & Co., Ltd.). In the case of Cosmoshine SRF (manufactured by Toyobo Co., Ltd.), applying the adhesive to an image display device reduces interfacial reflection and improves brightness. In the case of depolarizing adhesive, a colorless transparent plate is bonded to the image display device via the depolarizing adhesive. An image light control sheet 338 is also provided on the image output surface of the retroreflective member 5 to eliminate ghost images that appear on both sides of the normal image of the spatially floating image 3 due to unwanted light. In this embodiment, the retroreflective member 5 is positioned parallel to the horizontal plane in space, allowing the spatially floating image 3 to be displayed at an angle θ1 relative to the horizontal plane. To achieve this, the display surface of the image display device 1 is tilted by θ1 on the opposite side of the spatially floating image 3 relative to the horizontal plane. Furthermore, in this embodiment, the image display device 1 is equipped with a light source device 13 that generates specifically polarized light with a narrow angle with the liquid crystal display panel 11 and a diffusion characteristic.

[0034] <Configuration example of the third retro-reflection optical system forming the space floating image information display system> 8 is a diagram showing another example of the configuration of the main components of a retroreflecting optical system for realizing a space-floating image information display system. This space-floating image information display system is suitable for an observer to observe a space-floating image from diagonally above in front. The image display device 1 is configured with a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 is configured with a screen size ranging from a small one of about 5 inches to a large one exceeding 80 inches.

[0035] Image light from the liquid crystal display panel 11 is emitted toward the retroreflective member 5. Light from a light source device 13 with a narrow divergence angle, which will be described later, is incident on the liquid crystal panel 11 to generate an image light beam with a narrow divergence angle, which is then incident on the retroreflective member 5 to obtain a space-floating image 3. The space-floating image 3 is formed at a symmetrical position on the image display device 1 with the retroreflective member 5 as the plane of symmetry.

[0036] To eliminate ghost images generated by the space-floating image 3 and obtain a high-quality space-floating image 3, an image light control sheet 334 may be provided on the output side of the liquid crystal panel 11 shown in FIG. 14(A) to control the diffusion characteristics in unnecessary directions. On the other hand, as shown in FIG. 14(B), an image light control sheet 338 may also be provided on the image output surface of the retroreflective member 5 to eliminate ghost images generated on both sides of the normal image of the space-floating image 3 due to unnecessary light. By tilting the retroreflective sheet 5 (θ2) relative to the horizontal plane, the space-floating image 3 can be generated at an angle θ1 relative to the horizontal plane. Therefore, for example, if the configuration of FIG. 8 is incorporated into the top of a kiosk terminal and a space-floating image is displayed as an avatar on the top edge of the terminal, the image light is directed toward the observer's eyes, allowing for the observation of a high-brightness space-floating image.

[0037] In order to obtain the desired elevation angle and position of the floating image 3, it is sufficient to optimally design the inclination angle θ2 of the retroreflective member 5 and the inclination angle θ3 of the image display device 1, as in the first and second embodiments.

[0038] <Configuration example of the fourth retroreflection system forming the space floating image information display system> 9 is a diagram showing the main components of another example of a retroreflecting optical system for realizing a space-floating image information display system. This space-floating image information display system is suitable for an observer to observe a space-floating image from diagonally above. The image display device 1 is configured with a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 is configured with a screen size ranging from a small one of about 5 inches to a large one exceeding 80 inches.

[0039] In order to make the image light from the liquid crystal display panel 11 obliquely incident on the retroreflective member 5 placed directly opposite, a linear Fresnel sheet 105 as shown in FIG. 10 may be placed close to the image display surface of the liquid crystal panel 11 of the image display device 1 as the image light control sheet 334, and the image light may be refracted in the desired direction. In this case, a light-shielding layer may be provided on the vertical surface of the linear Fresnel to block the incidence of image light from sources other than the Fresnel lens, thereby suppressing the generation of unwanted light. Furthermore, by providing an anti-reflection film on the image light entrance and exit surfaces of the linear Fresnel sheet, the generation of unwanted light can be suppressed, resulting in good characteristics.

[0040] The image light is emitted toward the retroreflective member 5 by the image light control sheet 334 equipped with the linear Fresnel sheet 105 described above. Light from a narrow divergence angle light source device 13 (described later) is incident on the liquid crystal panel 11, generating an image light beam with a narrow divergence angle, which is incident on the retroreflective member 5, thereby obtaining a space-floating image 3. The space-floating image 3 is formed at a symmetrical position on the display surface of the image display device 1, with the retroreflective member 2 as the symmetry plane. In this embodiment, the retroreflective member 2 and the image display device 1 are positioned directly opposite each other, so when an observer looks into the retroreflective member 5 of the space-floating image information display device, the image displayed on the liquid crystal panel 11 overlaps with the space-floating image, significantly degrading the image quality of the space-floating image.

[0041] To prevent the above-described image light from overlapping with the spatially floating image, an image light control sheet is provided on the image light exit surface of the liquid crystal panel 11. For example, a viewing angle control film (VCF) from Shin-Etsu Polymer Co., Ltd. is suitable as this image light control sheet. Its structure is a sandwich structure in which transparent silicon and black silicon are alternately arranged and a synthetic resin is placed on the light entrance and exit surfaces, so it is expected to have the same effect as the ambient light control film of this embodiment. In this case, the viewing angle control film (VFC) has transparent silicon and black silicon stretched in a predetermined direction alternately arranged. Therefore, as shown in FIG. 13, it is recommended to tilt the stretching direction of the transparent silicon and black silicon of the image light control sheet 334 relative to the vertical direction of the pixel arrangement direction of the liquid crystal panel 11 (θ10 in the figure) to reduce moiré that occurs due to the pitch between the pixels and the ambient light control film.

[0042] In the fourth embodiment, the retroreflective member 5 is arranged parallel to the bottom surface of the housing. As a result, external light enters the retroreflective member 5 and enters the housing, resulting in a degradation in the quality of the generated space-floating image 3. To eliminate ghost images generated in the space-floating image 3 and obtain a high-quality space-floating image 3, as in the second and third embodiments, an image light control sheet 334 may be provided on the exit side of the liquid crystal panel 11 to control the diffusion characteristics in unnecessary directions, as shown in Figures 14(A) and 14(B). On the other hand, an image light control sheet 338 may also be provided on the image exit surface of the retroreflective member 5 to eliminate ghost images generated on both sides of the normal image of the space-floating image 3 due to unnecessary light. By arranging the above-described structure inside the housing, external light is prevented from entering the retroreflective member 5, thereby preventing the generation of ghost images.

[0043] If the Fresnel angle of the linear Fresnel sheet 105 shown in FIG. 10 is 20 degrees and the base material of the linear Fresnel sheet 105 is acrylic, the refractive index is 1.49 and the output angle θ9 of the linear Fresnel sheet is 30 degrees. When the output light beam from the image display device 1 is emitted perpendicular to the display surface, if the divergence angle of the light beam is ±20 degrees, the maximum angle of incidence on the output surface is +40 degrees. As a result, the output light beam angle from the linear Fresnel sheet 105 becomes a maximum of +70 degrees, which is 1.75 times larger. On the other hand, if the divergence angle is -20 degrees, the angle of incidence on the output surface is 10 degrees, and the divergence angle can be increased by 1.5 times from 20 degrees to 30 degrees.

[0044] Furthermore, it was also found that the intensity of ghost images 3a and 3b that occur in addition to the spatially floating image 3 shown in (A) and (B) can be reduced, that is, the brightness of the ghost images 3a and 3b can be reduced because the diffusion angle of the abnormally reflected light reflected by the retroreflective member 5 increases. Above, we have described the configuration and effects of the optical system in which the linear Fresnel sheet 105 shown in Fig. 10 is placed between the retroreflective member 5 and the image display device 1 for the purpose of increasing the diffusion angle and reducing ghost images.

[0045] Next, an embodiment of a housing using an optical system with a linear Fresnel sheet 105 in a space-floating image information display device will be described with reference to FIG. 11. As described above, the image light beam is refracted by the action of the linear Fresnel sheet 105. At this time, the direction of the light beam emitted from the image display device 1 is controlled so that the chief ray of the light beam (the light beam with the highest brightness) can obtain a desired angle θ9 with respect to the space-floating image surface 3. At this time, as shown in FIG. 10, the angle θ8 after refraction is calculated from the angle of incidence on the linear Fresnel sheet 105, the Fresnel angle, and the refractive index of the base material of the linear Fresnel sheet 105, and the angle of emission θ9 after refraction at the air interface can also be uniquely determined.

[0046] As a result, chief ray B1 of the image light emitted perpendicularly from the liquid crystal display panel 11 constituting the image display device 1 is refracted obliquely and enters the retroreflective member 5, and after being reflected by two reflective surfaces, forms a floating image 3 in a position symmetrical to the liquid crystal display panel 11. At this time, the image light beam has a narrow divergence angle due to the light source device 13 of the present invention (included in the image display device 1 shown in FIG. 11) which has narrow-angle diffusion characteristics as shown in FIG. 30, but the diffusion angle θ11 of one light beam B11 relative to the chief ray B1 is greatly expanded by the action of the Fresnel lens sheet 105. In addition, the other light beam B12 is diffused at a diffusion angle θ12 which is approximately equal to the original diffusion angle.

[0047] For this reason, when observing the floating image 3 in space, the brightness is highest when the image is viewed from the direction of the chief ray. For this reason, in a floating image information system having an optical system with a linear Fresnel sheet 105, in order to direct the floating image in space with maximum brightness in the monitoring direction of the observer, a hinge 513 is provided on a housing base 516 serving as a base to hold the housing 511 and rotate it relative to the housing base 516 (see angle θ13 in FIG. 11), and the housing 511 is connected to a support arm 512, one end of which is connected to the hinge 513. As a result, it becomes possible to rotate and hold the housing 511 relative to the housing base 516, so that the observer can monitor the floating image 3 in space with maximum brightness.

[0048] Furthermore, by providing the above-described mechanism, when the spatial floating image information display system is not in use, a compact storage form can be realized by storing the housing 511 in the space defined by the housing cover 515 provided on the housing base 516 and the housing base 516. The image display device 1 including a liquid crystal panel (not shown) and a light source (not shown), and the retroreflective member 5 are built into the inside of the housing 511. In addition, the back cover 514 has an inclined surface provided near the hinge, which prevents the back cover 514 of the housing 511 from contacting the housing base 516 when stored.

[0049] While a linear Fresnel sheet typically has a Fresnel lens formed parallel to one side of its outer shape, in the first embodiment of the present invention, the Fresnel lens shape has at least one boundary surface, as shown in FIG. 12(A). FIG. 12(A) shows the boundary surface between the inclined linear Fresnel sheet 517 and the inclined linear Fresnel sheet 518. As a result, the image light beam from the image displayed on the flat display of the image display device 1 located at the bottom in FIG. 13 is refracted in the direction indicated by the arrow in FIG. 12(A). As a result, the light output direction of the resulting floating image 3 in space can be set to two directions. Furthermore, if a linear Fresnel sheet is configured so that the boundary surface is two-sided, it goes without saying that the light output direction of the floating image 3 in space can be set to three directions.

[0050] Furthermore, as a second embodiment of the present invention, an eccentric Fresnel sheet 519 as shown in FIG. 12(B) has an eccentric circular Fresnel sheet structure, and the lens action obtained by the Fresnel shape causes the light emitted from the floating image 3 to exit in a direction perpendicular to the Fresnel lens surface. As a result, the image light beam from the image displayed on the flat display provided in the image display device 1 located on the lower side in FIG. 13 is refracted in the direction indicated by the arrow in FIG. 12(B). Here, in order to control the light emitted from the floating image 3, the eccentricity amount and Fresnel angle of the circular Fresnel sheet are optimally designed as parameters. Furthermore, by keeping the Fresnel angles of the linear Fresnel sheet and the circular Fresnel sheet constant, it is possible to achieve both control of the emitted light and a slim optical system set.

[0051] Although the above describes the technical means for controlling the emission direction of the image light beam from the image display device 1 by the action of the Fresnel lens, it goes without saying that the same effect can be obtained by electrically changing the refractive index or shape to control the emission direction of the image light beam and the emission direction and diffusion angle of the light from the spatially floating image. Furthermore, as will be described later, the same effect can be obtained by controlling the emission direction of the light source light beam incident on the liquid crystal panel 11 from the light source device 13.

[0052] <First Configuration Example of the Space Floating Image Information Display System> A first embodiment of a space-floating image information system using the four retroreflective optical systems described above is shown in Figure 15. A retroreflective member 5 is adhesively or glue-fixed to a transparent sheet 100. By using a structure that allows the distance between the image display device 1 and the retroreflective member 5 to be changed and the imaging position of the space-floating image 3 to be changed, it is possible to give movement to the space-floating image, and to realize an image information display device that can display pseudo-three-dimensional space-floating images.

[0053] <Second example of the configuration of the space floating image information display system> A second embodiment of the space-floating image information display system will be described with reference to FIG. 16. FIG. 16 shows a first embodiment in which a space-floating image display device 202 is incorporated into a tablet terminal. The space-floating image display device 202 and the flat display 200 are provided in the same housing 201. In addition, a sensing unit 203 that covers the entire display image 204 of the flat display 200 and the space-floating display 202 is provided at the end of the housing 201 where both the flat display 200 and the space-floating image display device 202 are located, on the same plane as the floating image 204. The sensing unit 203 can sense both the sensing area of ​​the flat display 200 and the sensing area of ​​the space-floating display 202 on the same plane, which is shown as sensing area 226 in FIG. 16. In addition, when a configuration is provided with two or more sensing areas, such as the sensing area of ​​the flat display 200 and the sensing area of ​​the space-floating display 202, they may exist parallel to each other on a plane, above and below each other, or behind and before and after each other. They may also exist on the same plane. In this case, the sensing unit 203 may be divided and installed for each sensing area. The space-floating image display device 202 and the flat display 200 may be installed side by side in the same housing 201. Although the present embodiment is described using the flat display 200, any display may be used, not limited to a flat display. In the second configuration example, the sensing area is positioned higher from the front of the device to the rear, and has a slope. This realizes an arrangement that makes input easy. The sensing unit will be described in detail later.

[0054] In this image information display system, if the wavelength of the light source of the TOF system, which is the ranging system of the sensing unit 203 used, is set to a long wavelength of 900 (nm) or more, it is less susceptible to the influence of external light. In this case, the user is given the illusion that the spatial operation input performed on the displayed floating image 204 can also be performed on the image display surface of the flat display 200. Therefore, spatial operation input can be performed without directly touching the display screen of the flat display 200.

[0055] Furthermore, the inventors conducted an experiment to determine how far the flat display 200 and the sensing area 226 should be apart so that the operator's fingers do not touch the surface of the flat display 200 even when performing spatial operations based on the screen displayed on the flat display 200. As a result of this experiment, it was found that by setting the imaging position of the floating image 204 40 mm or more away from the flat display 200, the probability that the operator will directly touch the screen of the flat display 200 can be reduced to 50% or less. Furthermore, by setting the distance 50 mm or more, operations will no longer directly touch the flat display 200.

[0056] The configuration described in FIG. 16 is not limited to the tablet terminal described above, but may also be incorporated into various other display devices such as ATMs, automatic ticket vending machines, kiosk terminals, and stationary display devices.

[0057] <Third Configuration Example of the Space Floating Video Information Display System> A third embodiment of the space-floating image information display system will be described with reference to FIG. 17. FIG. 17 shows a second embodiment in which a space-floating image display device 202 is incorporated into a tablet terminal. The space-floating image display device 202 and a flat display 200 are mounted in the same housing 201, and there is a first sensing unit 203a that senses a first sensing area (sensing region) 226a that covers the imaging area of ​​the space-floating image 204 of the space-floating image display device 202, and a second sensing unit 203b that senses a second sensing area 226b that covers the image display area of ​​the flat display 200. The first sensing area 226a and the second sensing area 226b are provided at the starting points of the space-floating image display device 202 and the flat display 200, respectively. Furthermore, the first sensing area 226a and the second sensing area 226b are arranged closely to each other. The first sensing area and the second sensing area exist parallel to each other or in front and behind each other on a plane. As shown in FIG. 15, the first sensing area and the second sensing area may be configured to exist on the same plane. The space floating image display device 202 and the flat display 200 may be installed side by side in the same housing 201. In this embodiment, the flat display 200 is used for explanation, but the display is not limited to a flat display and may be any display. In this embodiment, the area is arranged approximately parallel to the image display surface of the flat display 200. The sensing unit used here will also be described in detail later.

[0058] In the third embodiment of the video information display system described above, the user also has the illusion that the spatial operation input performed on the displayed floating-in-space image 204 can be performed on the image display surface of the flat display 200 in the same way. Therefore, spatial operation input can be performed without directly touching the display screen of the flat display 200.

[0059] In this regard, an evaluation was conducted using a prototype to assess finger contact with the flat display 200 using an actual device, and it was found that by positioning the imaging position of the floating image 204 at a distance of 50 mm or more from the flat display 200, the operator was able to perform spatial operation input to the video information display system without directly touching the screen of the flat display 200.

[0060] As described above, the configuration described in FIG. 17 is not limited to tablet terminals, but may be incorporated into various display devices such as ATMs, automatic ticket vending machines, kiosk terminals, and stationary display devices.

[0061] <Technical means for sensing spatial images> In order to allow a monitor (operator) to be connected to an information system bidirectionally via a space-floating image display device, sensing technology for pseudo-operating the space-floating image will be described below.

[0062] In the space-floating image information system, sensing information is read together with the space-floating image using a two-dimensional sensor (described later), enabling image manipulation of the displayed image.

[0063] This section describes a sensing technology for pseudo-operating a floating image in space, enabling a monitor (operator) to connect bidirectionally to an information system via a floating image display device. Figure 18 illustrates the principle of this sensing technology. A distance measuring device 203 incorporating a Time of Flight (TOF) system compatible with floating images is installed. A near-infrared light-emitting diode (LED) serving as the light source is synchronized with the system's signal. An optical element for controlling the divergence angle is provided on the LED's light-emitting side, and a pair of highly sensitive avalanche diodes with picosecond time resolution are used as light-receiving elements, aligned horizontally to correspond to the area. The LED light source emits light in synchronization with the system's signal. The phase shift Δt corresponds to the time it takes for the light to reflect off the target object (the monitor's fingertip) and return to the light-receiving element. The distance to the target is calculated from this time difference Δt, and the position and movement of the operator's finger are sensed as two-dimensional information, combined with the position information of multiple sensors arranged in parallel. Furthermore, it is possible to realize a space-floating information display system or a space-floating image display device that has a sensing function with few false detections for the display screen of a flat display and the space-floating image.

[0064] <Technical means to reduce ghost images> A technical means for realizing a high-quality spatial image display device with reduced ghost images as a spatial floating image display device will be described with reference to Fig. 14. In order to control the divergence angle and divergence angle of the image light from the liquid crystal panel 13 as the image display element in a desired direction, it is advisable to provide an image light control sheet 334 on the exit surface of the liquid crystal panel 13, as shown in Fig. 14(A). Furthermore, the image light control sheet 334 is provided on the light exit surface or the light entrance surface or both of the retroreflective member to absorb abnormal light that generates ghost images.

[0065] 14(A) and 14(B) show a specific method for applying the image light control sheet 334 to a spatial image display device. The image light control sheet 334 is provided on the output surface of a liquid crystal panel 335, which is an image display element. In this case, the following two methods (1) and (2) are effective in reducing moiré that occurs due to interference between the pixels of the liquid crystal panel 335 and the pitch of the transmissive portions 336 and light absorbing portions 337 of the image light control sheet 334.

[0066] (1) As shown in FIG. 13, the image light control sheet 334 is tilted by θ10 relative to the vertical stripes caused by the transmissive and light absorbing portions and the pixel arrangement of the liquid crystal panel 335 (shown as the liquid crystal panel 11 in FIG. 15).

[0067] (2) If the pixel size of the liquid crystal panel 335 is A (see the double-headed arrow A in Figure 14(A)) and the pitch of the vertical stripes of the image light control sheet 334 is B (see the double-headed arrow B in Figure 14(A)), this ratio (B / A) is selected outside the integer multiple.

[0068] Each pixel 339 on an LCD panel consists of three color pixels (RGB) arranged in parallel, and is generally square, so the moire pattern described above cannot be suppressed across the entire screen. Therefore, we experimentally determined that the tilt θ10 shown in (1) should be optimized between 5 and 25 degrees so that the moire pattern can be intentionally shifted to a location where the floating image is not displayed. While we have used an LCD panel as an example to reduce moire, the moire pattern that occurs between the retroreflective member 5 and the image light control sheet 334 is a linear structure. Therefore, as shown in Figure 4, by optimally tilting the image light control sheet along the X axis, it is possible to reduce large, low-frequency moire patterns that can be seen with the naked eye even with long wavelengths.

[0069] 14(A) is a vertical cross-sectional view of the image display device 1 of the present invention, in which an image light control sheet 334 is arranged on the image light output surface of a liquid crystal panel 335. The image light control sheet 334 is configured by alternately arranging light-transmitting portions 336 and light-absorbing portions 337, and is adhesively fixed to the image light output surface of the liquid crystal panel 335 by an adhesive layer 338.

[0070] Furthermore, as mentioned above, when a 7-inch WUXGA (1920 × 1200 pixels) liquid crystal display panel is used as the image display device 1, even if one pixel (one triplet) (the length of the double-headed arrow A shown in FIG. 14A) is approximately 80 μm, the pitch B of the image light control sheet 334, consisting of a 300 μm transmissive portion d2 and a 40 μm light-absorbing portion d1, may be 340 μm. This configuration ensures sufficient transmission characteristics, controls the diffusion characteristics of the image light from the image display device that causes abnormal light, and reduces ghost images that appear on both sides of the spatially floating image. Furthermore, in this case, making the thickness of the image control sheet at least two-thirds of the pitch B significantly improves the ghost reduction effect.

[0071] 14(B) is a vertical cross-sectional view of a retroreflective member of the present invention in which an image light control sheet 334 is disposed on the image light exit surface of the retroreflective member 5. The image light control sheet 334 is configured by alternatingly arranging light-transmitting portions 336 and light-absorbing portions 337, and is inclined at an inclination angle θ1 to match the exit direction of the retroreflected light. As a result, the abnormal light generated by the retroreflection described above is absorbed, while allowing the normally reflected light to pass through without loss.

[0072] When using a 7-inch WUXGA (1920 × 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) (the length of the double-headed arrow A in Figure 14(A)) is approximately 80 μm, if the pitch B is 420 μm, for example, consisting of a 400 μm transmissive portion d2 of the retroreflective part and a 20 μm light-absorbing portion d1, sufficient transmission characteristics are achieved, and the diffusion characteristics of the image light from the image display device, which causes abnormal light to be generated in the retroreflective member, are controlled, thereby reducing ghost images that appear on both sides of the spatially floating image.

[0073] The image light control sheet 334 described above also prevents external light from entering the interior of the spatial floating image display device, which leads to improved reliability of the components. For example, a viewing angle control film (VCF) from Shin-Etsu Polymer Co., Ltd. is suitable as this image light control sheet, and its structure is a sandwich structure in which transparent silicon and black silicon are alternately arranged with synthetic resin placed on the light entrance and exit surfaces, so it can be expected to have the same effect as the external light control film of this example.

[0074] <LCD panel performance> Incidentally, in a typical TFT (Thin Film Transistor) liquid crystal panel, the brightness and contrast performance differ depending on the light output direction due to the mutual characteristics of the liquid crystal and polarizer. In an evaluation in the measurement environment shown in Figure 31, the brightness and viewing angle characteristics in the short side (up and down) direction of the panel were superior at an angle slightly shifted (+5 degrees in this example) from the output angle perpendicular to the panel surface (output angle of 0 degrees), as shown in Figure 33. The reason for this is that in the short side (up and down) direction of the liquid crystal panel, the light twisting characteristic does not become 0 degrees when the applied voltage is at its maximum.

[0075] On the other hand, as shown in Figure 35, the contrast performance in the short side (up and down) direction of the panel is excellent in the range of -15 degrees to +15 degrees, and when combined with the brightness characteristics, the best characteristics are obtained when used in the range of ±10 degrees with 5 degrees as the center.

[0076] Furthermore, the brightness and viewing angle characteristics in the longitudinal (left-right) direction of the panel are superior at an output angle perpendicular to the panel surface (output angle of 0 degrees), as shown in Figure 32. The reason for this is that the light twisting characteristic in the longitudinal (left-right) direction of the liquid crystal panel becomes 0 degrees when the applied voltage is at its maximum.

[0077] Similarly, the contrast performance in the longitudinal (left-right) direction of the panel is excellent in the range of -5 degrees to -10 degrees, as shown in Fig. 34, and when combined with the brightness characteristics, the best characteristics are obtained when used in the range of ±5 degrees with -5 degrees as the center. For this reason, the image quality and performance of the image display device 1 are improved by making the light emitted from the liquid crystal panel incident on the liquid crystal panel from a direction that provides the best characteristics using the light beam direction conversion means (reflecting surfaces 307, 314, etc.) provided on the light guide of the light source device 13 described above, and modulating the light using a video signal.

[0078] In order to make the most of the brightness and contrast characteristics of the liquid crystal panel as an image display element, the image quality of the floating image can be improved by setting the incident light from the light source to the liquid crystal panel within the above-mentioned range.

[0079] <Light source light control method> In this embodiment, in order to improve the utilization efficiency of the light beam emitted from the light source device 13 and significantly reduce power consumption, in the image display device 1 comprising the light source device 13 and the liquid crystal display panel 11, the light from the light source device 13 is incident on the liquid crystal panel 11 at an incident angle that maximizes the characteristics of the liquid crystal panel 11, and then the image light beam is luminance-modulated in accordance with the image signal and emitted toward the retroreflective member. At this time, in order to reduce the set volume of the spatial floating image information display system, it is desired to increase the degree of freedom in the arrangement of the liquid crystal panel 11 and the retroreflective member. Furthermore, in order to form the floating image at the desired position after retroreflection and ensure optimal directionality, the following technical means are used.

[0080] 10 and 12, a transparent sheet made of optical components such as a linear Fresnel lens is provided on the image display surface of the liquid crystal panel 11 as a light direction conversion panel, and the image position of the floating image in space is determined by controlling the direction of emission of the incident light beam to the retroreflective optical element while providing high directivity. With this configuration, the image light from the image display device 1 reaches the observer efficiently with high directivity (straightness) like laser light, and as a result, it is possible to display high-quality floating images with high resolution and significantly reduce the power consumption of the image display device 1 including the light source device 13.

[0081] <Example 1 of video display device> Fig. 24 shows another example of the specific configuration of the image display device 1. Light source device 13 in Fig. 24 is similar to the light source device in Fig. 25 etc. This light source device 13 is configured by housing LEDs, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and has a liquid crystal display panel 11 attached to its upper surface. Also, an LED board on which LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and their control circuits are mounted are attached to one side of the case of light source device 13, and a heat sink (not shown), which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer surface of the LED board.

[0082] The liquid crystal display panel frame attached to the top surface of the case is configured to have attached thereto a liquid crystal display panel 11 attached to the frame, and further to have attached thereto an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light together with the LED elements 14a and 14b, which are solid-state light sources, based on a control signal from a control circuit (not shown here) that constitutes the electronic device.

[0083] <Example 1 of Light Source Device for Example 1 of Image Display Device> Next, the configuration of the optical system, such as the light source device housed in the case, will be described in detail with reference to Figures 25(a) and (b) as well as Figure 23. Figures 23 and 24 show LEDs 14a and 14b that constitute the light source, which are attached at predetermined positions relative to the collimator 15. Each collimator 15 is formed of a light-transmitting resin such as acrylic. As also shown in Figure 22(b), the collimator 15 has an outer peripheral surface 156 that has a conical convex shape obtained by rotating a parabolic cross section, and has a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center of its apex (the side that contacts the LED substrate).

[0084] Furthermore, the central part of the flat part (the side opposite to the apex) of the collimator 15 has a convex lens surface 154 that protrudes outward (or may be a concave lens surface that is recessed inward). Note that the parabolic surface 156 that forms the outer peripheral surface of the cone shape of the collimator 15 is set within an angle range that allows the light emitted from the LEDs 14a and 14b in the peripheral direction to be totally reflected therein, or a reflective surface is formed thereon.

[0085] The LEDs 14a and 14b are arranged at predetermined positions on the surface of the circuit board, 102. The substrate 102 is arranged and fixed to the collimator 15 so that the LEDs 14a and 14b on the surface are located at the center of the recess 153.

[0086] According to this configuration, the collimator 15 described above condenses the light emitted from the LED 14a or 14b, particularly the light emitted upward from the central portion (toward the right in the figure), into parallel light by the two convex lens surfaces 157, 154 that form the outer shape of the collimator 15. Furthermore, the light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the conical shape of the collimator 15, and is similarly condensed into parallel light. In other words, the collimator 15, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light, thereby improving the utilization efficiency of the generated light.

[0087] A polarization conversion element 21 is provided on the light exit side of the collimator 15. The polarization conversion element 21 may also be referred to as a polarization conversion member. As is clear from FIG. 24(a), this polarization conversion element 21 is configured by combining a columnar light-transmitting member having a parallelogram cross section (hereinafter referred to as a parallelogram prism) and a columnar light-transmitting member having a triangular cross section (hereinafter referred to as a triangular prism), and arranging a plurality of these in an array parallel to a plane perpendicular to the optical axis of the collimated light from the collimator 15. Furthermore, a polarization beam splitter (hereinafter referred to as a "PBS film") 211 and a reflective film 212 are alternately provided at the interface between adjacent light-transmitting members arranged in the array, and a λ / 2 phase plate 213 is provided on the exit surface from which light incident on the polarization conversion element 21 and transmitted through the PBS film 211 exits.

[0088] 24(a) is further provided on the exit surface of this polarization conversion element 21. That is, the light emitted from LED 14a or 14b is converted into parallel light by the action of collimator 15, enters synthesizing diffusion block 16, is diffused by texture 161 on the exit side, and then reaches light guide 17.

[0089] The light guide 17 is a rod-shaped member made of a translucent resin such as acrylic and having an approximately triangular cross section (see Figure 24(b)). As can be seen from Figure 25, the light guide 17 has a light incident portion (surface) 171 that faces the exit surface of the synthetic diffusion block 16 via a first diffuser plate 18a, a light guide light reflecting portion (surface) 172 that forms an inclined surface, and a light guide light exit portion (surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via a second diffuser plate 18b.

[0090] 23, which is a partially enlarged view, a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth pattern on the light guide light reflecting portion (surface) 172 of this light guide 17. The reflective surfaces 172a (line segments sloping upward to the right in the figure) form angles αn (n: natural number, for example, 1 to 130 in this example) with respect to the horizontal plane indicated by the dashed dotted line in the figure, and as an example, αn is set to 43 degrees or less (but 0 degree or more).

[0091] Light guide entrance portion (surface) 171 is formed in a curved convex shape inclined toward the light source. Accordingly, parallel light from the exit surface of synthetic diffusion block 16 is diffused and incident via first diffuser plate 18a, and as is clear from the figure, is bent (deflected) slightly upward by light guide entrance portion (surface) 171 before reaching light guide light reflecting portion (surface) 172, where it is reflected and reaches liquid crystal display panel 11 provided on the exit surface at the top of the figure.

[0092] According to the image display device 1 described above in detail, it is possible to further improve the light utilization efficiency and its uniform illumination characteristics, and at the same time, it is possible to manufacture a compact and low-cost device, including a modularized S-polarized light source device. In the above explanation, the polarization conversion element 21 is described as being attached after the collimator 15, but the present invention is not limited to this, and similar functions and effects can be obtained by providing it in the optical path leading to the liquid crystal display panel 11.

[0093] The light guide light reflecting portion (surface) 172 has a number of alternating reflective surfaces 172a and connecting surfaces 172b formed in a sawtooth pattern. The illumination light beam is totally reflected by each reflective surface 172a and directed upward. The light beam then enters the light redirecting panel 54, which adjusts the directional characteristics of the light beam by providing a narrow-angle diffuser plate on the light guide light exiting portion (surface) 173. The light exiting direction of the image display device 1 is controlled by the light redirecting panel 54 provided on the upper surface of the light source device 13. As a result, the light exiting from the liquid crystal display panel 11 is also controlled, thereby controlling the light diffusion direction of the spatially floating image produced by the spatially floating image information system using the image display device 1. In this embodiment, the light redirecting panel 54 is provided between the light guide exiting surface 173 and the liquid crystal display panel 11. However, the same effect can be achieved by providing the light redirecting panel 54 on the exiting surface of the liquid crystal display panel 11.

[0094] In a typical TV device, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in the horizontal direction of the screen (the display direction corresponding to the X-axis of the graph in FIG. 30(A)) and the vertical direction of the screen (the display direction corresponding to the Y-axis of the graph in FIG. 30(B)), as shown in the plot curves of "conventional characteristics (X direction)" in FIG. 30(A) and "conventional characteristics (Y direction)" in FIG. 30(B).

[0095] In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel of this embodiment are, for example, as shown in the plot curves of "Example 1 (X direction)" in Figure 30(A) and "Example 1 (Y direction)" in Figure 30(B).

[0096] In one specific example, when the viewing angle at which the brightness is 50% (brightness reduced to about half) of the brightness when viewed from the front (angle of 0 degrees) is set to 13 degrees, this angle is about 1 / 5 of the diffusion characteristics of a typical home TV (angle of 62 degrees). Similarly, in one example where the vertical viewing angles are set unevenly between the upper and lower sides, the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized so that the upper viewing angle is held down (narrowed) to about 1 / 3 of the lower viewing angle.

[0097] By setting the viewing angle and other settings as described above, the amount of light in the image directed toward the user's viewing direction increases dramatically (significantly improving image brightness) compared to conventional LCD TVs, and the brightness of the image becomes more than 50 times greater.

[0098] Furthermore, in the case of the viewing angle characteristics shown in "Example 2" in Fig. 30, if the viewing angle at which the brightness of the image obtained when viewed from the front (angle of 0 degrees) is 50% (brightness reduced to about half) is set to 5 degrees, the angle (narrow viewing angle) will be about 1 / 12 of the diffusion characteristics (angle of 62 degrees) of a typical home TV device. Similarly, in an example where the vertical viewing angle is set equally on the top and bottom sides, the reflection angle and the area of ​​the reflective surface of the reflective light guide are optimized so that the vertical viewing angle is reduced (narrowed) to about 1 / 12 of the conventional value.

[0099] By making these settings, the brightness (amount of light) of the image in the viewing direction (the direction of the user's line of sight) is significantly improved compared to conventional LCD TVs, and the brightness of the image is more than 100 times higher.

[0100] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux directed in the viewing direction can be concentrated, significantly improving light utilization efficiency. As a result, even when using a liquid crystal display panel for general TV applications, by adjusting the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create a video display device that is compatible with information display systems facing bright outdoor environments.

[0101] When using a large LCD panel, the brightness of the screen can be improved by directing the light from the periphery of the screen inward toward the viewer when the viewer is facing the center of the screen. Figure 27 shows the convergence angle between the long and short sides of the LCD panel when the distance L from the LCD panel to the viewer and the panel size of the image display device (screen ratio 16:10) are used as parameters. The upper diagram assumes that the image is viewed with the LCD panel screen in portrait orientation (hereinafter also referred to as "portrait viewing"). In this case, the convergence angle can be set to match the short side of the LCD panel (see the direction of arrow V in Figure 27 as appropriate).

[0102] As a more specific example, as shown in the plot graph in Figure 27, when a 22" panel is used vertically and the viewing distance is 0.8 m, by setting the convergence angle to 10 degrees, the image light from each corner (four corners) of the screen can be effectively projected or output toward the viewer.

[0103] Similarly, when viewing a 15" panel in portrait orientation, if the viewing distance is 0.8 m, a convergence angle of 7 degrees will allow image light from the four corners of the screen to be effectively directed toward the viewer. As described above, the overall brightness of the screen can be improved by directing image light from the periphery of the screen to the viewer who is in the optimum position to view the center of the screen, depending on the size of the LCD panel and whether it is used portrait or landscape.

[0104] As shown in Figure 30 above, the basic configuration involves a light source device directing a light beam with a narrow angle of directionality to the liquid crystal display panel 11, which is then luminance-modulated according to the video signal. The video information displayed on the screen of the liquid crystal display panel 11 is then reflected by a retroreflective member, and the resulting spatially floating image is displayed indoors or outdoors via a transparent member 100.

[0105] A number of other examples of the light source device will be described below, and any of these other examples of the light source device may be used in place of the light source device in the example of the image display device described above.

[0106] As mentioned above, when a large LCD panel is used, the light from the periphery of the screen can be directed inward so that it faces the viewer when the viewer is facing the center of the screen, improving the overall brightness of the screen, but on the other hand, binocular parallax occurs depending on whether the viewer uses their left or right eye to view the image. Figure 28 shows the convergence angle between the long and short sides of the LCD panel, calculated based on the positions of the left and right eyes, when the distance L from the LCD panel to the viewer and the panel size of the image display device (screen ratio 16:10) are used as parameters.

[0107] The smaller the panel size and the closer the monitoring distance, the larger the convergence angle in binocular vision by the left and right eyes. When using a small panel of 7 inches or less, the convergence angle due to binocular parallax is an important requirement, so for a panel of 7 inches or less, for example, the light diffusion characteristics of the light source shown in Figure 30 should be expanded or given directional characteristics so that the image light is directed toward the optimal monitoring range of the system.

[0108] Furthermore, depending on the required specifications of the system, it may be necessary to optimally design the shape, surface roughness, inclination, etc. of the reflective surface of the light guide of the light source device 13 described above in order to obtain horizontal and vertical directional characteristics and diffusion characteristics.

[0109] <Light source device example 1> Next, another example of the light source device will be described with reference to Fig. 19. Figs. 19(a) and (b) are diagrams in which the liquid crystal display panel 11 and the diffusion plate 206 are partially omitted in order to explain the light guide 311.

[0110] 19 shows a state in which the LEDs 14 constituting the light source are mounted on a substrate 102. The LEDs 14 and the substrate 102 are attached to a reflector 15 at predetermined positions.

[0111] 19(a), the LEDs 14 are arranged in a row in a direction parallel to the side (short side in this example) of the liquid crystal display panel 11 on which the reflector 300 is arranged. In the example shown in the figure, the reflector 300 is arranged corresponding to the arrangement of the LEDs. Note that a plurality of reflectors 300 may be arranged.

[0112] In one embodiment, the reflectors 300 are each made of a plastic material. Alternatively, the reflectors 300 may be made of a metal material or a glass material, but plastic materials are easier to mold, so in this embodiment, plastic materials are used.

[0113] 19(b), the inner surface (right side in the figure) of the reflector 300 has a reflecting surface (hereinafter may be referred to as a "paraboloid") 305 shaped like a paraboloid cut at its meridian plane. The reflector 300 converts the divergent light emitted from the LED 14 into approximately parallel light by reflecting it off the reflecting surface 305 (paraboloid), and directs the converted light to be incident on an end face of the light guide 311. In one specific example, the light guide 311 is a transmissive light guide.

[0114] The reflecting surface of reflector 300 has a shape asymmetric with respect to the optical axis of the light emitted from LED 14. Furthermore, reflecting surface 305 of reflector 300 is a parabolic surface as described above, and by placing the LED at the focus of this parabolic surface, the light flux after reflection is converted into approximately parallel light.

[0115] Because the LED 14 is a surface light source, even if it is placed at the focus of a parabolic surface, the divergent light from the LED cannot be converted into completely parallel light, but this does not affect the performance of the light source of the present invention. The LED 14 and reflector 300 form a pair. Furthermore, to ensure the specified performance when the LED 14 is attached to the substrate 102 with an accuracy of ±40 μm, the number of LEDs attached to the substrate should be limited to a maximum of 10 or less, and considering mass production, it is best to limit it to around 5.

[0116] Although the LED 14 and reflector 300 are partly close to each other, heat can be dissipated into the space on the opening side of the reflector 300, reducing the temperature rise of the LED. This makes it possible to use a plastic molded reflector 300. As a result, with this reflector 300, the shape precision of the reflective surface can be improved by 10 times or more compared to a reflector made of glass material, thereby improving light utilization efficiency.

[0117] On the other hand, a reflective surface is provided on the bottom surface 303 of the light guide 311, and the light from the LEDs 14 is converted into a parallel beam by the reflector 300, reflected by the reflective surface, and emitted toward the liquid crystal display panel 11 disposed opposite the light guide 311. The reflective surface provided on the bottom surface 303 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel beam from the reflector 300, as shown in Fig. 19. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel beam from the reflector 300.

[0118] Furthermore, the shape of the reflective surface provided on the bottom surface 303 may be flat. In this case, the refractive surface 314 provided on the surface of the light guide 311 facing the liquid crystal display panel 11 refracts the light reflected by the reflective surface provided on the bottom surface 303 of the light guide 311, making it possible to adjust with high precision the amount of light and the emission direction of the light beam heading toward the liquid crystal display panel 11. As a result, the amount of light and the emission direction of the light incident on the liquid crystal display panel 11 and the light emitted from the liquid crystal display panel 11 can also be controlled with high precision, so that in a spatial image information display system using an image display device that uses this light source, the diffusion direction and diffusion angle of the image light of the spatially floating image can be set to desired values.

[0119] 19(a) and 19(b), the refractive surface 314 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300. The inclinations of the plurality of surfaces refract the light reflected by the reflective surface provided on the bottom surface 303 of the light guide 311 toward the liquid crystal display panel 11. Alternatively, the refractive surface 314 may be a transmissive surface.

[0120] If a diffuser plate 206 is provided in front of the liquid crystal display panel 11, the light reflected by the reflective surface is refracted toward the diffuser plate 206 due to the multiple inclinations of the refracting surface 314. That is, the extension direction of the multiple surfaces with different inclinations of the refracting surface 314 is parallel to the extension direction of the multiple surfaces with different inclinations of the reflective surface provided on the bottom surface 303. By making the extension directions of both surfaces parallel, the angle of the light can be adjusted more appropriately. On the other hand, the LEDs 14 are soldered to the metallic substrate 102. This allows heat generated by the LEDs to be dissipated into the air via the substrate.

[0121] The reflector 300 may be in contact with the substrate 102, or a space may be left between them. If a space is left between them, the reflector 300 is attached to the housing. By leaving a space between them, heat generated by the LED can be dissipated into the air, improving the cooling effect. As a result, the operating temperature of the LED can be reduced, allowing for the maintenance of luminous efficiency and a longer lifespan.

[0122] <Another example of light source device 2> Next, the configuration of an optical system relating to a light source device in which the light utilization efficiency is improved by 1.8 times by using polarization conversion compared to the light source device shown in Fig. 19 will be described in detail with reference to Fig. 20A, Fig. 20B, Fig. 20C, and Fig. 20D. Note that the sub-reflector 308 is not shown in Fig. 20A.

[0123] 20, 20B, and 20C show a state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured as a unit 312 having a plurality of blocks, with the reflector 300 and the LEDs 14 forming a pair of blocks.

[0124] 20A(2) is the base material of the substrate 102. Generally, the metallic substrate 102 generates heat, so it is preferable to use a plastic material or the like for the substrate 320 in order to insulate (heat-insulate) the heat of the substrate 102. The material and shape of the reflecting surface of the reflector 300 may be the same as those of the example of the light source device in FIG.

[0125] The reflecting surface of the reflector 300 may also have an asymmetric shape with respect to the optical axis of the light emitted from the LED 14. The reason for this will be explained with reference to Fig. 20A(2). In this embodiment, the reflecting surface of the reflector 300 is a parabolic surface, as in the example of Fig. 19, and the center of the light-emitting surface of the LED, which is a surface light source, is located at the focal position of the parabolic surface.

[0126] Furthermore, due to the characteristics of the parabolic surface, the light emitted from the four corners of the light-emitting surface also becomes approximately parallel light beams, and the only difference is the direction of emission. Therefore, even if the light-emitting part has an area, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected as long as the distance between the polarization conversion element and the reflector 300 located downstream is short.

[0127] Furthermore, even if the mounting position of the LED 14 is shifted in the XY plane with respect to the focal point of the corresponding reflector 300, an optical system can be realized that can reduce the decrease in light conversion efficiency for the reasons described above. Furthermore, even if the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light beam simply moves in the ZX plane, and the mounting precision of the LED, which is a surface light source, can be significantly reduced. In this embodiment, the reflector 300 having a reflective surface formed by meridionally cutting out a portion of a paraboloid has been described, but the LED may also be placed in a portion of the cutout with the entire paraboloid as the reflective surface.

[0128] 20B(1) and 20C, the present embodiment is characterized in that the divergent light from the LED 14 is reflected by the parabolic surface 321 and converted into approximately parallel light, and then the parallel light is incident on the end face of the polarization conversion element 21 at the subsequent stage, and aligned into a specific polarization by the polarization conversion element 21. With this characteristic configuration, the present embodiment achieves a light utilization efficiency that is 1.8 times that of the example in FIG. 26 described above, thereby realizing a highly efficient light source.

[0129] At this time, the substantially parallel light resulting from the reflection of the divergent light from the LED 14 by the parabolic surface 321 is not all uniform. Therefore, by adjusting the angular distribution of the reflected light by the reflecting surface 307 having a plurality of inclinations, it is possible for the light to be incident on the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11.

[0130] In the example shown in this figure, the direction of the light (principal ray) entering the reflector from the LED is approximately parallel to the direction of the light entering the LCD panel. This arrangement is easy to design, and placing the heat source below the light source device is preferable because it allows air to escape upwards, reducing the temperature rise of the LED.

[0131] 20B(1), in order to improve the capture rate of divergent light from LED 14, the light beam that cannot be captured by reflector 300 is reflected by sub-reflector 308 provided on light-shielding plate 309 arranged above the reflector, and is reflected by the slope of sub-reflector 310 below to enter the effective area of ​​polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency. That is, in this embodiment, a part of the light reflected by reflector 300 is reflected by sub-reflector 308, and the light reflected by sub-reflector 308 is reflected by sub-reflector 310 in a direction toward light guide 306.

[0132] The substantially parallel light beam, which has been aligned to a specific polarization by the polarization conversion element 21, is reflected by a reflection shape provided on the surface of the reflective light guide 306 toward the liquid crystal display panel 11 disposed opposite the light guide 306. At this time, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is optimally designed by the shape and arrangement of the reflector 300 described above, and the shape (cross-sectional shape) of the reflective surface of the reflective light guide, as well as the inclination and surface roughness of the reflective surface.

[0133] The shape of the reflective surface provided on the surface of the light guide 306 is such that multiple reflective surfaces are arranged opposite the exit surface of the polarization conversion element, and the inclination, area, height, and pitch of the reflective surfaces are optimized according to the distance from the polarization conversion element 21, thereby achieving the desired light intensity distribution of the light beam incident on the liquid crystal display panel 11, as described above.

[0134] As shown in FIG. 20B(2), the reflective surface 307 of the reflective light guide can be configured with multiple inclinations on one surface, thereby enabling more precise adjustment of reflected light. Note that the reflective surface may be configured with multiple surfaces, polyhedrons, or curved surfaces. Furthermore, the diffusing effect of the diffuser 206 achieves a more uniform light intensity distribution. Light incident on the diffuser plate closer to the LED can be uniformly distributed by changing the inclination of the reflective surface. As a result, the amount and direction of light beams directed toward the liquid crystal display panel 11 can be precisely adjusted. Therefore, the amount and direction of light incident on and emitted from the liquid crystal display panel 11 can be similarly precisely controlled. Therefore, in a spatial image information display system using an image display device with this light source, the diffusion direction and diffusion angle of the image light of a floating image can be set to desired values.

[0135] In this embodiment, a plastic material such as heat-resistant polycarbonate is used for the base material of the reflecting surface 307. The angle of the reflecting surface 307 immediately after emission from the λ / 2 plate 213 varies depending on the distance between the λ / 2 plate and the reflecting surface.

[0136] In this embodiment, the LED 14 and the reflector 300 are also partially adjacent to each other, but the temperature rise of the LED can be reduced by dissipating heat into the space on the opening side of the reflector 300. Furthermore, the substrate 102 and the reflector 300 may be arranged upside down as shown in Figures 20A, 20B, and 20C.

[0137] However, if the substrate 102 is placed on top, the substrate 102 will be close to the liquid crystal display panel 11, which may make the layout difficult. Therefore, as shown in the figure, placing the substrate 102 below the reflector 300 (on the side farther from the liquid crystal display panel 11) will simplify the internal configuration of the device.

[0138] A light-shielding plate 410 may be provided on the light-incident surface of the polarization conversion element 21 to prevent unnecessary light from entering the downstream optical system. This configuration achieves a light source device that suppresses temperature rise. The polarizer provided on the light-incident surface of the liquid crystal display panel 11 reduces temperature rise by absorbing the uniformly polarized light beam of the present invention. However, when reflected by the reflective light guide, the polarization direction rotates, and some of the light is absorbed by the incident-side polarizer. Furthermore, the temperature of the liquid crystal display panel 11 also rises due to absorption by the liquid crystal itself and temperature rise caused by light incident on the electrode pattern. However, there is sufficient space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, allowing for natural cooling.

[0139] Fig. 20D is a modified example of the light source device of Fig. 20B(1) and Fig. 20C. Fig. 20D(1) illustrates a modified example of a portion of the light source device of Fig. 20B(1). The other configuration is the same as that of the light source device described above in Fig. 20B(1), so illustration and repeated explanation will be omitted.

[0140] 20D(1), the height of recess 319 of sub-reflector 310 is adjusted to be lower than phosphor 114 so that the chief ray of fluorescence output laterally (in the X-axis direction) from phosphor 114 (see the straight line extending in a direction parallel to the X-axis in FIG. 20D(1)) can exit from recess 319 of sub-reflector 310. Furthermore, the height of light-shielding plate 410 is adjusted to be lower in the Z-axis direction relative to the position of phosphor 114 so that the chief ray of fluorescence output laterally from phosphor 114 can enter the effective area of ​​polarization conversion element 21 without being blocked by light-shielding plate 410.

[0141] Furthermore, the reflective surface of the convex portion of the uneven top of the sub-reflector 310 reflects the light reflected by the sub-reflector 308 in order to guide the light reflected by the sub-reflector 308 to the light guide 306. Therefore, the height of the convex portion 318 of the sub-reflector 310 is adjusted so that the light reflected by the sub-reflector 308 is reflected and incident on the effective area of ​​the polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency.

[0142] 20A(2), the sub-reflector 310 is arranged to extend in one direction and has an uneven shape. Furthermore, the top of the sub-reflector 310 has unevenness with one or more recesses periodically arranged in one direction. By using such an uneven shape, it is possible to configure the sub-reflector 310 so that the chief ray of the fluorescence output laterally from the phosphor 114 enters the effective area of ​​the polarization conversion element 21.

[0143] Furthermore, the concave and convex shapes of sub-reflector 310 are periodically arranged at a pitch such that concave portions 319 are located at positions where LEDs 14 are present. That is, each of phosphors 114 is periodically arranged in one direction corresponding to the pitch of the arrangement of concave portions of the concave and convex shapes of sub-reflector 310. Note that when phosphor 114 is provided in LED 14, phosphor 114 may be expressed as a light-emitting portion of the light source.

[0144] 20D(2) illustrates a modified example of a portion of the light source device of FIG. 20C. Other configurations are the same as those of the light source device of FIG. 20C, and therefore illustrations and repeated explanations are omitted. As shown in FIG. 20D(2), the sub-reflector 310 is not necessary, but as in FIG. 20D(1), the height of the light-shielding plate 410 is adjusted to be lower in the Z-axis direction relative to the position of the phosphor 114 so that the chief ray of the fluorescence output laterally from the phosphor 114 is not blocked by the light-shielding plate 410 and enters the effective area of ​​the polarization conversion element 21.

[0145] 20A, 20B, 20C, and 20D, side walls 400 may be provided as shown in Fig. 20A(1) to prevent dust from entering the space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, to prevent stray light from being generated outside the light source device, and to prevent stray light from entering from outside the light source device. When side walls 400 are provided, they are arranged to sandwich the space between the light guide 306 and the diffuser plate 206.

[0146] The light exit surface of the polarization conversion element 21, which emits light that has been polarization-converted by the polarization conversion element 21, faces a space surrounded by the side wall 400, the light guide 306, the diffuser plate 206, and the polarization conversion element 21. Furthermore, a reflective surface having a reflective film or the like is used for a portion of the inner surface of the side wall 400 that laterally covers the space into which light is output from the exit surface of the polarization conversion element 21 (the space to the right of the exit surface of the polarization conversion element 21 in FIG. 20B(1)). In other words, the surface of the side wall 400 facing the space has a reflective area having a reflective film. By using this portion of the inner surface of the side wall 400 as a reflective surface, the light reflected by the reflective surface can be reused as light source light, thereby improving the brightness of the light source device.

[0147] Of the inner surfaces of the side wall 400, the surface that covers the side of the polarization conversion element 21 is made to have low light reflectivity (such as a black surface without a reflective film). This is because if light is reflected from the side surface of the polarization conversion element 21, light with an unexpected polarization state will be generated, causing stray light. In other words, by making the above surface a surface with low light reflectivity, it is possible to prevent or suppress the occurrence of stray light in the image and light with an unexpected polarization state. Furthermore, the side wall 400 may be configured to have holes in parts to allow air to pass through, thereby improving the cooling effect.

[0148] 20A, 20B, 20C, and 20D have been described assuming a configuration using the polarization conversion element 21. However, these light source devices may be configured without the polarization conversion element 21. In this case, a light source device can be provided at a lower cost.

[0149] <Another example of light source device 3> Next, the configuration of the optical system for a light source device using a reflective light guide 304 based on the light source device shown in Example 1 of the light source device will be described in detail with reference to Figures 21A(1), (2), (3) and 21B.

[0150] 21A shows a state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured as a pair of blocks, each consisting of a collimator 18 and an LED 14, and a unit 328 having a plurality of blocks. Since the collimator 18 in this embodiment is located close to the LED 14, a glass material is used for the collimator 18 in consideration of heat resistance. The shape of the collimator 18 is the same as that described for the collimator 15 in FIG. 20. In addition, by providing a light shielding plate 317 in the stage before the light enters the polarization conversion element 21, it is possible to prevent or suppress unwanted light from entering the optical system in the subsequent stage, thereby reducing the temperature rise caused by the unwanted light.

[0151] Other configurations and effects of the light source shown in Fig. 21A are the same as those in Fig. 20A, Fig. 20B, Fig. 20C, and Fig. 20D, and therefore repeated explanations will be omitted. The light source device in Fig. 21A may be provided with side walls, as explained in Fig. 20A, Fig. 20B, and Fig. 20C. The configurations and effects of the side walls have already been explained, and therefore repeated explanations will be omitted.

[0152] Fig. 21B is a cross-sectional view of Fig. 21A(2). The configuration of the light source shown in Fig. 21B is common to part of the structure of the light source in Fig. 20, and has already been explained in Fig. 18, so repeated explanation will be omitted.

[0153] <Another example of light source device 4> Next, the light source device of Fig. 25 is configured with a unit 328 having a plurality of blocks, each of which is a pair of the collimator 18 and the LED 14 used in the light source device shown in Fig. 21. The configuration of the optical system relating to the light source device using the LEDs and the reflective light guide 504 arranged at both ends of the back surface of the liquid crystal display panel 11 will be described in detail with reference to Figs. 25(a), (b), and (c).

[0154] 25 shows a state in which LEDs 14 constituting a light source are mounted on a substrate 505, and these are configured as units 503 having a plurality of blocks, each of which is a pair of a collimator 18 and an LED 14. The units 503 are arranged at both ends of the rear surface of the liquid crystal display panel 11 (in this embodiment, three units are arranged side by side in the short side direction). Light output from the units 503 is reflected by a reflective light guide 504 and enters the liquid crystal display panel 11 (shown in FIG. 25(c)) arranged opposite.

[0155] As shown in Fig. 25(c), the reflective light guide 504 is divided into two blocks corresponding to the units arranged at each end, and is arranged so that the central part is the highest. Because the collimator 18 is located close to the LED 14, a glass material is used for the collimator 18 in consideration of its heat resistance to the heat emitted from the LED 14. The shape of the collimator 18 is the same as that described for the collimator 15 in Fig. 20.

[0156] Light from LED 14 enters polarization conversion element 501 via collimator 18. The distribution of light entering reflective light guide 504 at the subsequent stage is adjusted by the shape of optical element 81. That is, the light intensity distribution of the light beam entering liquid crystal display panel 11 is optimally designed by adjusting the shape and arrangement of collimator 18 described above, the shape of optical element 81, the diffusion characteristics, the shape (cross-sectional shape) of the reflective surface of the reflective light guide, the inclination of the reflective surface, and the surface roughness of the reflective surface.

[0157] As shown in FIG. 25(b), the shape of the reflective surface provided on the surface of the reflective light guide 504 is such that multiple reflective surfaces are arranged opposite the exit surface of the polarization conversion element, and the inclination, area, height, and pitch of the reflective surfaces are optimized according to the distance from the polarization conversion element 21. Furthermore, by dividing the area of ​​the same reflective surface (i.e., the surface facing the polarization conversion element) into a polyhedron, the light intensity distribution of the light beam incident on the liquid crystal display panel 11 can be adjusted (optimized) to a desired value, as described above. This allows the light intensity and exit direction of the light beam toward the liquid crystal display panel 11 to be adjusted with high precision. As a result, the light intensity and exit direction of the light incident on the liquid crystal display panel 11 and the light exiting from the liquid crystal display panel 11 can also be controlled with high precision. Therefore, in a spatial image information display system using an image display device that uses this light source, the diffusion direction and diffusion angle of the image light of the spatially floating image can be set to desired values ​​(see the four solid arrows indicating "reflected light from the light guide" in FIG. 26).

[0158] 20B, the reflective surface provided on the reflective light guide can adjust the reflected light with higher precision by configuring one surface (the area where light is reflected) to have a shape with multiple inclinations (in the example of FIG. 25, the XY plane is divided into 14 sections with different inclinations), thereby preventing the reflected light from leaking from the side of light source device 13. Also, by providing light-shielding wall 507, it is possible to prevent light from leaking in any direction other than the desired direction (towards liquid crystal display panel 11).

[0159] Furthermore, the units 503 arranged on the left and right sides of the reflective light guide 504 in Fig. 25 may be replaced with the light source device in Fig. 20. That is, a configuration may be adopted in which a plurality of light source devices (substrate 102, reflector 300, LED 14, etc.) in Fig. 20 are prepared and these plurality of light source devices are arranged in positions facing each other, as shown in Figs. 25(a), (b), and (c).

[0160] FIG. 26(B) shows a light source device configured with six units 503 shown in FIG. 26(A) arranged on the top and six on the bottom. The light source device shown in FIG. 26(B) has units 503, each with five LEDs arranged horizontally, arranged as described above, and the desired brightness is obtained by controlling the current using a single power supply. Therefore, as a light source device for illuminating an LCD panel, the light source brightness can be controlled for each area illuminated by each unit 503. The configuration shown in FIG. 26 includes a reflective surface 222 and a reflective surface 502 different from the reflective surface 222. Of these, the reflective surface 222 has a horizontal lattice-like shape or a strip-like shape with a predetermined width. On the other hand, the reflective surface 502 has a vertical and horizontal lattice-like shape. By optimally designing the shape of these fine lattices and the inclination of the dividing surfaces, the desired output light distribution (output direction and diffusion characteristics of the output light) can be obtained. 16 and 17, the amount of light and the direction of emission of the light beam toward the liquid crystal display panel 11 can be adjusted with high precision. As a result, similar to the two embodiments described above, the amount of light and the direction of emission of the light incident on the liquid crystal display panel 11 and the light emitted from the liquid crystal display panel 11 can be controlled with high precision, and therefore, in a spatial image information display system using an image display device that uses this light source, the diffusion direction and diffusion angle of the image light of the spatial floating image can be set to desired values.

[0161] 22 is a cross-sectional view showing an example of the shape of the diffuser plate 206. As described above, the divergent light output from the LED is converted into approximately parallel light by the reflector 300 or the collimator 18, converted into specific polarization by the polarization conversion element 21, and then reflected by the light guide. The light beam reflected by the light guide then passes through the flat portion of the incident surface of the diffuser plate 206 and enters the liquid crystal display panel 11 (see the two solid arrows indicating "reflected light from the light guide" in FIG. 22).

[0162] Furthermore, of the light emitted from the polarization conversion element 21, the divergent light beam is totally reflected by the inclined surfaces of the protrusions having inclined surfaces provided on the incident surface of the diffuser plate 206, and then enters the liquid crystal display panel 11. In order to totally reflect the light emitted from the polarization conversion element 21 by the inclined surfaces of the protrusions of the diffuser plate 206, the angle of the inclined surfaces of the protrusions is changed based on the distance from the polarization conversion element 21. If the angle of the inclined surface of the protrusions on the side farther from the polarization conversion element 21 or farther from the LEDs is α, and the angle of the inclined surface of the protrusions on the side closer to the polarization conversion element 21 or closer to the LEDs is α', then α is smaller than α' (α<α'). By setting in this way, it becomes possible to effectively utilize the polarization-converted light beam.

[0163] <Technology for controlling diffusion characteristics of video display devices> One method for adjusting the diffusion distribution of the image light from the liquid crystal display panel 11 is to provide a lenticular lens between the light source device 13 and the liquid crystal display panel 11 or on the surface of the liquid crystal display panel 11 and optimize the shape of the lens. That is, by optimizing the shape of the lenticular lens, it is possible to adjust the emission characteristics of the image light (hereinafter also referred to as "image luminous flux") emitted in one direction from the liquid crystal display panel 11.

[0164] Alternatively or additionally, a microlens array may be arranged in a matrix on the surface of the liquid crystal display panel 11 (or between the light source device 13 and the liquid crystal display panel 11), and the arrangement may be adjusted. That is, by adjusting the arrangement of the microlens array, it is possible to adjust the emission characteristics in the X-axis and Y-axis directions of the image light beam emitted from the image display device 1, and as a result, it is possible to obtain an image display device with desired diffusion characteristics.

[0165] As a further configuration example, two lenticular lenses may be combined and arranged at a position where the image light emitted from the image display device 1 passes, or a sheet that adjusts the diffusion characteristics by arranging a microlens array in a matrix may be provided. By configuring the optical system in this way, the brightness (relative brightness) of the image light in the X-axis and Y-axis directions can be adjusted according to the reflection angle of the image light (reflection angle with the vertical reflection as the reference (0 degrees)).

[0166] In this example, by using such a lenticular lens, it is possible to obtain excellent optical characteristics that are clearly different from the graphs (plot curves) of conventional characteristics, as shown in the graphs (plot curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in Figure 29(b). Specifically, in the plot curves of Example 1 (Y direction) and Example 2 (Y direction), the brightness characteristic in the vertical direction is made steeper, and further, by changing the balance of the directional characteristics in the up and down direction (positive and negative directions of the Y axis), it is possible to increase the brightness (relative brightness) of light due to reflection and diffusion.

[0167] Therefore, according to this embodiment, the image light has a narrow diffusion angle (high straightness) and contains only specific polarization components, like the image light from a surface-emitting laser image source, and can be adjusted to suppress the ghost images that would occur in the retroreflective member when using an image display device using conventional technology, and to efficiently deliver the spatially floating image caused by retroreflection to the viewer's eyes.

[0168] Furthermore, the light source device described above can provide directional characteristics with significantly narrower angles in both the X-axis and Y-axis directions compared to the diffusion characteristics of emitted light from a general liquid crystal display panel shown in (A) and (B) of Figure 30 (indicated as "conventional characteristics" in the figure). In this embodiment, by providing such narrow-angle directional characteristics, it is possible to realize an image display device that emits nearly parallel image light beams in a specific direction and emits light of a specific polarization.

[0169] FIG. 30 shows an example of the characteristics of the lenticular lens employed in this embodiment. This example particularly shows the characteristics in the X direction (vertical direction) relative to the Z axis. Characteristic O shows a luminance characteristic that is symmetrical vertically, with the peak of the light emission direction occurring at an angle of approximately 30 degrees upward from the vertical direction (0 degrees). Furthermore, the plot curves of characteristic A and characteristic B shown in the graph of FIG. 30 show examples of characteristics in which the image light above the peak luminance is further concentrated at approximately 30 degrees, thereby increasing the luminance (relative luminance). Therefore, in characteristic A and characteristic B, as can be seen by comparing them with the plot curve of characteristic O, the luminance (relative luminance) of light drops sharply in the region where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ>30°).

[0170] That is, with the optical system including the lenticular lens described above, when the image light beam from the image display device 1 is incident on the retroreflective member, the emission angle and viewing angle of the image light aligned to a narrow angle by the light source device 13 can be adjusted, significantly improving the flexibility of retroreflective sheet installation. As a result, the flexibility of the image position of the floating image that is reflected or transmitted through the window glass and focused at the desired position can be significantly improved. As a result, it is possible to efficiently deliver light with a narrow diffusion angle (high linearity) and only specific polarization components to the eyes of viewers indoors or outdoors. As a result, even if the intensity (brightness) of the image light from the image display device 1 is reduced, viewers can accurately recognize the image light and obtain information. In other words, by reducing the output of the image display device 1, it is possible to realize an information display system with low power consumption.

[0171] <Structural example of retroreflective material> FIG. 36 shows another configuration of the second retroreflective member 5 of the present invention. In the retroreflective member 50 of FIG. 36(A) or the retroreflective member 500 of FIG. 36(B), which are other examples of the second retroreflective member 5 of FIG. 2, the first light control panel 221 and the second light control panel 222 are formed by arranging optical members 20 of a predetermined width or distance, each having a plurality of strip-shaped reflective portions perpendicular to one side of the flat plates 17 and 18. The first light control panel 221 and the second light control panel 222 are fixed to the transparent flat plates 17 and 18, which are disposed approximately perpendicular to the reflective portions of the optical members 20. Here, the reflective portions of the optical members 20 constituting the first light control panel 221 and the second light control panel 222 are arranged so as to intersect (orthogonal in this embodiment) in a planar view, and will hereinafter be referred to as a planar light reflective portion 220. In this embodiment, the first light control panel 221 and the second light control panel 222 are bonded with an adhesive. Furthermore, the first light control panel 221 and the second light control panel 222 are adhered and fixed to the transparent flat plates 17 and 18. Although the transparent flat plates 17 and 18 are referred to as transparent flat plates in this specification, they are not limited to being transparent and may be non-transparent. The light control panels may also be referred to as light control members.

[0172] The first light control panel 221 will be described below. In the first light control panel 221, multiple optical members 20 are arranged in parallel, and a flat light reflecting portion 220 is provided on one surface of the optical members 20. The flat light reflecting portion 220 is generally formed by depositing a reflective film on the surface of the optical members 20 using vapor deposition or sputtering technology, and an easy-to-handle adhesive is used to secure them together. The first light control panel 221 and the transparent flat plate 17 are bonded and fixed with a UV-curable acrylic adhesive by irradiating UV rays from the transparent flat plate 17 side. Similarly, in the second light control panel 222, the optical members 20 are arranged in parallel, and the optical members 20 are bonded to each other. The second light control panel 222 is also bonded and fixed to the transparent flat plate 18. Experiments have made it clear that if a liquid such as water penetrates the end face of a retroreflective member 50 manufactured using the method described above, causing the adhesive surface to separate and an interface to form, allowing external light to enter the retroreflective member due to reflection at the adhesive / air interface in addition to the normal reflective surface, an observer will recognize this as an abnormal phenomenon due to the double reflective surface created by the interface and will conclude that the member is faulty.

[0173] To solve the above-mentioned problems, the inventors discovered that applying a resin-based adhesive 217, which is normally used as an adhesive, to the joints of the end faces of the retroreflective member 50, as shown in Figure 36(A), and covering the exposed joints at the end faces, can prevent the penetration of moisture and other liquids. Silicon-based adhesives can expand and contract even when the transparent flat plates 17, 18 are made of resin, even if the external dimensions change due to expansion caused by temperature fluctuations or moisture absorption. This allows them to absorb the shape changes of the transparent flat plates 17, 18, stably cover the joints, and prevent the penetration of liquids such as moisture. Furthermore, the resin-based adhesive 217 may be transparent or opaque. Figure 36(A) uses a transparent resin-based adhesive 217. In this embodiment, the transparent resin-based adhesive 217 is an acrylic-modified silicone resin-based adhesive, such as Cemedine Super XG No. 777.

[0174] In addition to the edge treatment described above, it is also effective to prevent the intrusion of moisture and other liquids by adhering moisture-proof tape 218 to the edge of retroreflective member 500, as shown in Figure 36(B). Furthermore, by covering the edge with adhesive 217 and then adhering moisture-proof tape 218, a double-layered structure preventing the intrusion of liquids such as moisture can be achieved, resulting in even better waterproofing. Furthermore, moisture-proof tape 218 may be either transparent or opaque; for example, Scotch Powerful Waterproof Repair Tape BBT-50 is used. A spatial floating image information display system using the resulting retroreflective member can be realized that is highly resistant to environmental changes.

[0175] <Method for manufacturing retroreflective members> As described above, in the retroreflective member 50 or the retroreflective member 500, the optical members 20 of the respective light control members 221 and 222 are arranged in parallel and cross each other. Furthermore, the light control members 221 and 222 are fixed to the transparent flat plates 17 and 18 with an ultraviolet-curing adhesive.

[0176] Generally, the transparent flat plates 17 and 18 are made of plastic that does not contain ultraviolet absorbing materials (which absorb light of 400 nm or less) so that ultraviolet rays can pass through. However, in an ultraviolet exposure test conducted by the inventors, a problem occurred in which the plastic substrate reacted to ultraviolet rays and turned yellow. To address this problem, the transparent flat plate 17, which is placed on the side where external light is incident, uses plastic that contains ultraviolet absorbing materials, and ultraviolet rays are irradiated from the opposite side of the transparent flat plate 17 to bond the light control member 221 with an ultraviolet-curing adhesive. The other transparent flat plate 18 uses plastic that does not contain ultraviolet absorbing materials, and the light control member 222 is bonded by irradiating ultraviolet rays from the direction of the transparent flat plate 18 to bond and fix with an ultraviolet-curing adhesive.

[0177] As a result, the floating video information display system 2920 can also be applied to an outdoor vending machine 2900, which has a drink display section 2901, a bill slot 2902, a drink dispenser 2903, a change dispenser 2904, a coin dispenser 2905, etc., as shown in FIG. 37.

[0178] In the example shown in FIG. 37, for example, when selecting a product, concierge 2921 is displayed on floating video information display system 2920, and a voice saying, "Welcome. The screen will change to numeric buttons. Please select the product number you want," is played, followed by numeric buttons 2922 and decision button 2923. When a product number is pressed using numeric button 2922 and decision button 2923 is pressed, the product with that product number is dispensed from drink dispenser 2903, concierge 2921 is displayed again, and a voice saying, for example, "Thank you very much. We look forward to seeing you again," is played to end the process.

[0179] Various embodiments or examples (i.e., specific examples) to which the present invention is applied have been described in detail above. However, the present invention is not limited to the above-described embodiments (specific examples) and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0180] The light source device described above is not limited to the space floating image display device, but can also be applied to information display devices such as HUDs, tablets, digital signage, and the like.

[0181] The technology according to this embodiment displays high-resolution, high-brightness floating images in a floating state, allowing users to operate the system without worrying about contact infection. Using the technology according to this embodiment in a system used by an unspecified number of users reduces the risk of contact infection and provides a contactless user interface that can be used without anxiety. The present invention, which provides such technology, contributes to the "Good Health and Well-Being" goal, one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0182] Furthermore, the technology according to the above-described embodiment reduces the divergence angle of the emitted image light and aligns it with a specific polarization, thereby efficiently reflecting only the normal reflected light from the retroreflective material, resulting in high light utilization efficiency and a bright, clear, floating image in space. The technology according to the present embodiment can provide a highly usable non-contact user interface that can significantly reduce power consumption. The present invention, which provides such technology, contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation" and "Make cities and towns sustainable."

[0183] Furthermore, the technology according to the above-described embodiment makes it possible to form a floating image using highly directional (linear) image light. The technology according to this embodiment makes it possible to provide a non-contact user interface with low risk of people other than the user peeking at the floating image, even when displaying images that require high security, such as those in bank ATMs or train station ticket machines, or highly confidential images that should be kept secret from people directly facing the user, by displaying highly directional image light. By providing the above-described technology, the present invention contributes to "Sustainable Cities and Communities," one of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Explanation of symbols]

[0184] 1...image display device, 2...first retroreflective member, 5...second retroreflective member, 3...spatial image (space-floating image), 100...transmissive plate, 13...light source device, 54...light direction conversion panel, 105...linear Fresnel sheet, 101...absorptive polarizing sheet (absorptive polarizing plate), 200...flat display, 201...housing, 203...sensing system, 217...resin-based adhesive, 218...moisture-proof tape, 226...sensing area, 102...substrate, 11, 335...liquid crystal display panel, 206...diffuser, 21...polarization conversion element, 300...reflector, 213...λ / 2 plate, 306...reflective light guide, 307...reflective surface, 308, 310...sub-reflector, 204...space-floating image, 334...image light control sheet, 336...transmitting portion, 337...light absorbing portion, 81...optical element, 501...polarization conversion element, 503...unit, 507...light-shielding wall, 401, 402...light-shielding plate, 320...substrate, 511...housing, 512...support arm, 513...hinge, 514...back cover, 515...housing cover, 516...housing base, 517, 518...inclined linear Fresnel sheet, 519...eccentric Fresnel sheet, 2900...vending machine, 2901...drink display portion, 2902...bill slot, 2903...drink outlet, 2904...change outlet, 2905...coin slot, 2920...space-floating video information display system, 2921...concierge, 2922...number buttons, 2923...decision button.

Claims

1. A space floating image display device, a display panel for displaying images; a light source device that emits light to the display panel; a retroreflective member that reflects image light from the display panel and displays a real image floating in space in the air using the reflected light; The retroreflective member includes two light control members, and the two light control members are bonded together with an adhesive; The retroreflective member has moisture-proof tape attached to an end face of the joint where the two light control members are joined.

2. 2. The space floating image display device according to claim 1, The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and the moisture-proof tape is further attached to the retroreflective member.

3. 3. The space floating image display device according to claim 1, A space floating image display device, wherein a silicone-based adhesive is applied as the adhesive to the end faces where the two light control members are joined.

4. 4. The space floating image display device according to claim 1, the light control member includes an optical member; A reflective film is formed on one surface of the optical member by vapor deposition or sputtering technology.

5. 5. The space floating image display device according to claim 1, The light control member is adhered and fixed to the flat plate by ultraviolet light irradiation from the flat plate side with an ultraviolet-curing acrylic adhesive.

6. 6. The space floating image display device according to claim 5, The space floating image display device has two flat plates, one of which is made of plastic containing an ultraviolet absorbing material.

7. A retroreflective member that reflects light from a light source device, The retroreflective member includes two light control members, the two light control members are bonded together with an adhesive; The light control member includes optical members arranged in parallel and fixed to a flat plate provided substantially perpendicular to the reflecting portions of the optical members, The retroreflective member has moisture-proof tape attached to an end face of the joint where the two light control members are joined.

8. The retroreflective member according to claim 7, The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and further has the moisture-proof tape attached thereto.

9. The retroreflective member according to claim 7 or 8, A retroreflective member in which a silicone-based adhesive is applied as the adhesive to the end surface where the two light control members are joined.

10. The retroreflective member according to any one of claims 7 to 9, the light control member includes an optical member; A retroreflective member in which a reflective film is formed on one surface of the optical member by vapor deposition or sputtering technology.

11. The retroreflective member according to any one of claims 7 to 10, The light control member is a retroreflective member that is bonded and fixed to the flat plate by irradiating ultraviolet rays from the flat plate side with an ultraviolet-curing acrylic adhesive.

12. The retroreflective member according to any one of claims 7 to 11, The retroreflective member has two flat plates, one of which uses a plastic containing an ultraviolet absorbing material.

13. A space floating image display device, a display panel for displaying images; a light source device that emits light to the display panel; a retroreflective member that reflects image light from the display panel and displays a real image floating in space in the air using the reflected light; The retroreflective member includes two light control members, and the two light control members are bonded together with an adhesive; the light control member is bonded and fixed to the flat plate by ultraviolet light irradiation from the flat plate side with an ultraviolet-curing acrylic adhesive; There are two flat plates, and one of the flat plates is made of plastic containing an ultraviolet absorbing material, The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and further has moisture-proof tape attached thereto.

14. A retroreflective member that reflects light from a light source device, The retroreflective member includes two light control members, the two light control members are bonded together with an adhesive; The light control member includes optical members arranged in parallel and fixed to a flat plate provided substantially perpendicular to the reflecting portions of the optical members, There are two flat plates, and one of the flat plates is made of plastic containing an ultraviolet absorbing material, The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and further has moisture-proof tape attached thereto.

15. A space floating image display device, a display panel for displaying images; a light source device that emits light to the display panel; a retroreflective member that reflects image light from the display panel and displays a real image floating in space in the air using the reflected light; The retroreflective member includes two light control members, and the two light control members are bonded together with an adhesive; The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and further has moisture-proof tape attached thereto.

16. In the spatial floating image display device according to claim 15, A space floating image display device, wherein a silicone-based adhesive is applied as the adhesive to the end faces where the two light control members are joined.

17. In the spatial floating image display device according to claim 15 or claim 16, the light control member includes an optical member; A reflective film is formed on one surface of the optical member by vapor deposition or sputtering technology.

18. A spatial floating image display device according to any one of claims 15 to 17, The light control member is adhered and fixed to the flat plate by ultraviolet light irradiation from the flat plate side with an ultraviolet-curing acrylic adhesive.

19. In the space floating image display device according to claim 18, The space floating image display device has two flat plates, one of which is made of plastic containing an ultraviolet absorbing material.

20. A retroreflective member that reflects light from a light source device, The retroreflective member includes two light control members, the two light control members are bonded together with an adhesive; The light control member includes optical members arranged in parallel and fixed to a flat plate provided substantially perpendicular to the reflecting portions of the optical members, The retroreflective member has an adhesive applied to the end face of the joint where the two light control members are joined, and further has moisture-proof tape attached thereto.

21. The retroreflective member according to claim 20, A retroreflective member in which a silicone-based adhesive is applied as the adhesive to the end surface where the two light control members are joined.

22. The retroreflective member according to claim 20 or claim 21, the light control member includes an optical member; A retroreflective member in which a reflective film is formed on one surface of the optical member by vapor deposition or sputtering technology.

23. The retroreflective member according to any one of claims 20 to 22, The light control member is a retroreflective member that is bonded and fixed to the flat plate by irradiating ultraviolet rays from the flat plate side with an ultraviolet-curing acrylic adhesive.

Images