Space-floating image display device

Abstract

To suitably display a video to the outside of a space, thereby the present invention contributing to the sustainable development goals: 3, Good Health and Well-Being, 9, Industry, Innovation and Infrastructure, 11, Sustainable Cities and Communities.SOLUTION: A spatial floating video display device comprises: a first display panel for displaying a video; a light source device for the first display panel; a retroreflective member for reflecting video light from the first display panel and causing a spatial floating video of the actual image to be displayed in the air by reflected light; a second display panel for displaying a video on a surface; and a sensor for sensing both of operational input to the spatial floating video and operational input to the video displayed by the second display panel.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a spatial floating image display device.

Background Art

[0002] As a spatial floating information display system, a video display device that directly displays an image toward the outside and a display method that is displayed as a spatial screen are already known. Also, a detection system for reducing false detection of an operation on the operation surface of the displayed spatial image is disclosed in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a spatial floating information display system, a video display device that directly displays an image toward the outside and a display method that is displayed as a spatial screen are already known. However, in the above-described conventional spatial floating video information display system, there are no preventive measures for problems that occur when external light enters the retroreflective member that generates the spatial floating video, and as a detection system for operating the video displayed on a video display system with a composite configuration in which a spatial floating video display device and a flat display are provided side by side on the same operation surface in space, there is no consideration for an optimization technique for the design including the light source of the video display device that is the video source of the spatial floating video.

[0005] The object of the present invention is to provide a method and technology for displaying suitable images in a spatial floating information display system or spatial floating image display device, which enables spatial floating image display with high visibility (apparent resolution and contrast) and reduced influence of ambient light, and which allows for high-precision manipulation of the spatial image and the image displayed on the flat panel display in a system installed in conjunction with a flat panel display. [Means for solving the problem]

[0006] To solve the above problems, for example, the configuration described in the claims is adopted. The present application includes multiple means for solving the above problems, but one example is a spatial floating image display device. The spatial floating image display device as an example of the present application includes a first display panel for displaying an image, a light source device for the first display panel, a retroreflective member that reflects the image light from the first display panel and displays a spatial floating image of a real image in the air with the reflected light, a second display panel for displaying an image on a surface, and the spatial floating image Touch operation Input and video displayed on the second display panel Touch operation Both inputs on the same plane It is equipped with a sensing sensor. [Effects of the Invention]

[0007] According to the present invention, even when ambient light is incident, there is no degradation in the image quality of the floating image, and floating image information can be displayed suitably. Furthermore, by providing a floating image display device and a display, operation input can be performed without directly touching the display screen. Other issues, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the configuration of a retroreflective member and the location where a floating image is generated in space according to one embodiment of the present invention. [Figure 2] This is an explanatory diagram illustrating the mechanism for generating ghost images caused by abnormal light rays generated by retroreflection according to one embodiment of the present invention. [Figure 3] This is an explanatory diagram illustrating the mechanism of abnormal ray generation that occurs in retroreflective materials used in other spatial floating image information systems. [Figure 4] This is an explanatory diagram illustrating the mechanism for eliminating abnormal light rays generated when ambient light is incident on a retroreflective member according to one embodiment of the present invention. [Figure 5] This is a characteristic diagram showing the optimal usage conditions for a retroreflective member in a spatial floating image information display system according to one embodiment of the present invention. [Figure 6] This figure shows an example of the main component configuration and retroreflective component configuration of a spatial floating image information display system according to one embodiment of the present invention. [Figure 7] This figure shows the main component configuration and a second embodiment of the retroreflective component configuration of a spatial floating image information display system according to one embodiment of the present invention. [Figure 8] This figure shows the main component configuration and a third embodiment of the retroreflective component configuration of a spatial floating image information display system according to one embodiment of the present invention. [Figure 9] This figure shows a fourth embodiment of the main component configuration and retroreflective component configuration of a spatial floating image information display system according to one embodiment of the present invention. [Figure 10] This is an explanatory diagram illustrating the operating principle of the optical element that refracts video light used in the spatially floating video information display system of the present invention. [Figure 11] This is an explanatory diagram illustrating the arrangement of an optical element and an image source used in the spatial floating image information display system of the present invention, which prevents the viewer from directly viewing the displayed image of the image source. [Figure 12] This is a cross-sectional view showing the arrangement of members that block abnormal light rays generated in a retroreflective section according to one embodiment of the present invention. [Figure 13] This figure shows the main components of the first embodiment of a spatial floating image information display system according to one embodiment of the present invention. [Figure 14] This figure shows the external appearance and main components of a second embodiment of a spatial floating video information display system according to one embodiment of the present invention. [Figure 15]It is a diagram showing the appearance and main component configuration of a second embodiment of another spatial floating video information display system according to an embodiment of the present invention. [Figure 16] It is an explanatory diagram for explaining sensing means provided in a spatial floating video information display system according to an embodiment of the present invention. [Figure 17] It is a diagram showing another example of the specific configuration of a different type of light source device. [Figure 18A] It is a structural diagram showing another example of the specific configuration of a different type of light source device. [Figure 18B] It is a diagram excerpting a part of another example of the specific configuration of a different type of light source device. [Figure 18C] It is a diagram excerpting a part of another example of the specific configuration of a different type of light source device. [Figure 18D] It is a diagram excerpting a part of another example of the specific configuration of a different type of light source device. [Figure 19A] It is a structural diagram showing another example of the specific configuration of a different type of light source device. [Figure 19B] It is a diagram showing another example of the specific configuration of a different type of light source device. [Figure 20] It is an enlarged diagram showing the surface shape of the light guide diffusion part of another example of the specific configuration of the light source device. [Figure 21] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 22] It is a structural diagram showing an example of the specific configuration of the light source device. [Figure 23] It is a perspective view, top view, and cross-sectional view showing an example of the specific configuration of the light source device. [Figure 24] It is a perspective view and top view showing an example of the specific configuration of the light source device. [Figure 25] It is an explanatory diagram for explaining the light source diffusion characteristics of the video display device. [Figure 26] It is an explanatory diagram for explaining the light source diffusion characteristics of the video display device. [Figure 27] It is an explanatory diagram for explaining the diffusion characteristics of the video display device. [Figure 28] It is an explanatory diagram for explaining the diffusion characteristics of the video display device. [Figure 29] This figure shows the coordinate system used to measure the visual characteristics of a liquid crystal panel. [Figure 30] This diagram shows the brightness angle characteristics (longitudinal direction) of a typical liquid crystal panel. [Figure 31] This diagram shows the brightness angle characteristics (short-side direction) of a typical liquid crystal panel. [Figure 32] This figure shows the angular contrast characteristics (longitudinal direction) of a typical liquid crystal panel. [Figure 33] This figure shows the angular contrast characteristics (short-axis direction) of a typical liquid crystal panel. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments described below (hereinafter also referred to as "the Disclosure"). The present invention also extends to the spirit of the invention or the scope of the technical ideas described in the claims, or their equivalents. Furthermore, the configurations of the embodiments (examples) described below are merely illustrative, and various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed herein.

[0010] Furthermore, in the drawings used to illustrate the present invention, components having the same or similar functions are assigned 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 embodiments, images floating in space are referred to as "floating images." Instead of this term, you may also use terms such as "aerial image," "spatial image," "floating image," "floating optical image of a displayed image," or "floating optical image of a displayed image." The term "floating image" primarily used in the description of embodiments is used as a representative example of these terms.

[0011] This disclosure relates to an information display system capable of displaying images as floating images inside or outside a store (space) by transmitting images from a large-area image light source through a transparent partitioning material such as the glass of a shop window. This disclosure also relates to a large-scale digital signage system composed of multiple such information display systems.

[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 on 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 to a specific polarization, only the normal reflected light can be efficiently reflected by the retroreflective material. As a result, the light utilization efficiency is high, and ghost images that occur in addition to the main floating image, which was a problem in conventional retroreflection methods, can be suppressed, and a clear floating image can be obtained.

[0013] Furthermore, the device including the light source of this disclosure can provide a novel and highly usable floating spatial image information display system that can significantly reduce power consumption. In addition, according to the technology of this disclosure, it is possible to provide a floating spatial image information display system for vehicles that can display so-called one-way floating spatial images that are visible from outside the vehicle through shield glass including the windshield, rear window, and side windows of the vehicle.

[0014] On the other hand, conventional floating video information display systems combine an organic EL panel or liquid crystal display panel (liquid crystal panel or display panel) as a high-resolution color display image source with a retroreflective member. In the first retroreflective member 2 used in conventional floating video display devices, the image light diffuses at a wide angle. Therefore, in addition to the reflected light that is normally reflected by the retroreflective member, which is the first embodiment composed of a polyhedron as shown in Figure 3, six ghost images, including the ghost images indicated by symbols 3a and 3f, are generated by the image light incident at an oblique angle, as the shape used for the retroreflective member 2a is a hexahedron as shown in Figure 3, thus degrading the image quality of the floating video. Furthermore, the same floating video, which consists of ghost images, can be viewed by people other than the viewer, posing a major security challenge.

[0015] Furthermore, as shown in Figure 1(A), the second retroreflective member 5 used in the floating image display device is formed by arranging numerous strip-shaped planar light-reflecting parts at a constant pitch on one side surface of transparent flat plates 18 and 17 of constant thickness, respectively, for the first optical control panel 221 and the second optical control panel 222. Here, the light-reflecting parts of the optical members 20 constituting the first optical control panel 221 and the second optical control panel 222 are arranged intersecting (orthogonal in this embodiment) when viewed from above.

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

[0017] The mechanism of image formation for the floating image in space will be explained in detail below using Figures 1 and 2. The image light emitted from the image display device 1, which is provided on one side of the second retroreflective member 5, is reflected by the planar light reflecting part C (the reflective surface of the light reflecting member 20) of the second light control member 222, and then reflected by the planar light reflecting part C' (the reflective surface of the light reflecting member 20) of the first light control member 221, thereby forming a floating image 3 (real image) on the outside of the second retroreflective member 5 (in the space on the other side). In other words, by using this second retroreflective member 5, a floating image information device is established, and the image from the image display device 1 can be displayed in space as a floating image in space.

[0018] As described above, the second retroreflective member 5 has two reflective surfaces, so in addition to the floating image 3 in space, two ghost images 3a and 3b are generated, corresponding to the number of reflective surfaces, as shown in Figures 2(A) and (B).

[0019] Furthermore, it was found that when ambient light intensity is high, if light is incident from the upper surface of the second retroreflective member 5, the spacing between the reflective surfaces (less than 300 μm) becomes shorter, causing optical interference and resulting in the observation of rainbow-colored reflected light, which has the drawback of allowing the observer to recognize the presence of the retroreflective member. Therefore, to prevent interference light generated by the pitch of the reflective surfaces of the retroreflective member 5 from returning to the observer due to ambient light incidence, the area where interference light is generated was experimentally determined using the measurement environment shown in Figure 4, with the incident angle of ambient light as a parameter. The obtained results are shown in Figure 5. When the pitch of the reflective surfaces is 300 μm and the height of the reflective surfaces is 300 μm, it was found that if the inclination angle θYZ of the retroreflective member is tilted to 35 degrees or more, the interference light does not return to the observer.

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

[0021] Based on the above considerations, the inventors investigated a retroreflective optical system that achieves high image quality of the floating images obtained in a floating image information display system using a second retroreflective member that, in principle, generates less ghost images, and arrived at the present invention. The details will be explained below with reference to the figures.

[0022] <Example of the configuration of the first retroreflective optical system forming a spatially floating video information display system> Figure 6 shows an example of the configuration of a retroreflective optical system used to realize the spatial floating image information display system of this disclosure. Figure 6 also shows the overall configuration of the spatial floating image information display system in this embodiment. Referring to Figure 6, for example, according to the spatial floating image information display system of this disclosure (hereinafter also referred to as "this system"), if the spatial floating image information display system is placed on a desk for the person monitoring the spatial floating image, the spatial floating image will be viewed downward at an angle θ6. At this time, it has been found that the optimal arrangement for monitoring the spatial floating image is to arrange the image so that the sum 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 spatial floating image (θ2 + θ1) is approximately equal.

[0023] As described above, the floating spatial image is formed symmetrically with respect to the second retroreflective member 5 and the image display device 1, so the angles θ1 and θ2 formed by each arrangement are equal. Therefore, once the angle θ6 at which the observer looks into the floating spatial image display system is determined, it is preferable to arrange the image display device 1 and the second retroreflective member 5 in the retroreflective optical system at an angle θ2 = θ6 / 2. Furthermore, a predetermined gap 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. In addition, it is necessary to determine the gap L2 relative to L1 in order to structurally obtain the aforementioned θ2.

[0024] The configuration of the spatially floating video information display system of this disclosure will be described in more detail. As shown in Figure 6, it comprises a video display device 1 that emits video light of a specific polarization to a narrow angle and a second retroreflective member 5. The video display device 1 comprises 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 polarization having narrow-angle diffusion characteristics.

[0025] The image light of a specific polarization from the image display device 1 is transmitted to the surface of the second retroreflective member 5 that is in contact with the outside of the device (not shown). An absorbing polarizing sheet 101 with an anti-reflective coating on its surface is provided to selectively transmit the image light of the specific polarization, and absorb the other polarization contained in the ambient light. This prevents the reflected light reflected by the surface of the second retroreflective member 5 from influencing the spatially floating image obtained.

[0026] Here, the absorbing 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 is transmitted through the absorbing polarizing sheet 101. The transmitted image light forms a floating image 3 in space at a position symmetrical with respect to the retroreflective member 5.

[0027] Furthermore, the light that forms the floating image 3 is a collection of light rays that converge from the retroreflective member 5 to 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, unlike the diffused image light formed on a screen by a typical projector, the floating image 3 is an image with high directivity.

[0028] Therefore, in the configuration shown in Figure 6, when a user views the image from the direction shown in the figure, the floating image 3 is visible as a bright image. However, when other people view the image from above, below, or in front of or behind the page, the floating image 3 is not visible at all. This characteristic is highly suitable for systems that display images requiring high security or highly confidential images that should be concealed from people directly facing the user.

[0029] Furthermore, depending on the performance of the retroreflective member 5, the polarization axes of the reflected image light may become misaligned. In this case, some of the image light with misaligned polarization axes is absorbed by the absorption-type polarizing sheet 101 described above. As a result, unwanted reflected light is not generated in the retroreflective optical system, and a decrease in the image quality of the floating image can be prevented or suppressed.

[0030] Furthermore, in the floating video display device using the retroreflective optical system of this disclosure, even if a monitor looks closely at the floating video, the display screen of the video display device 1 is shielded from light by the reflective surface of the retroreflective member 5, making it more difficult to directly view the display image of the video display device 1 compared to when the video display device 1 and the retroreflective member are facing each other.

[0031] <Example of the configuration of the second retroreflective optical system forming a spatially floating video information display system> Figure 7 shows the main components of another example of a retrooptics system for realizing a spatial floating image information display system according to one embodiment of the present invention. This spatial image information display system is suitable for a monitor to observe a spatial 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 having narrow-angle diffusion characteristics. The liquid crystal display panel 11 can range from small ones with a screen size of about 5 inches to large ones exceeding 80 inches. The image light from the liquid crystal display panel 11 is emitted toward a retroreflective member (retroreflective part or retroreflective plate) 5.

[0032] Light from a narrow-angle light source device 13 (described later) is incident on the liquid crystal panel 11 to generate a narrow-angle image beam, which is then incident on the retroreflective member 5 to obtain a floating image 3. The floating image 3 is formed at symmetrical positions on the image display device 1 with the retroreflective member 5 as the plane of symmetry. To eliminate the ghost image generated at this time and obtain a high-quality floating image 3, it is preferable to provide an image light control sheet 334, whose structure is shown in Figure 12(A), on the output side of the liquid crystal panel 11 to control the diffusion characteristics in unwanted directions. Furthermore, since the reflectivity of reflective members such as retroreflective members can be increased in principle with image light from the liquid crystal panel 11, it is preferable to use S polarization. However, if the observer uses polarized sunglasses, the floating image will be reflected or absorbed by the polarized sunglasses. As a countermeasure, a depolarization element 339 is provided that optically converts a portion of the image light of a specific polarization to the other polarization, thereby simulating natural light. This allows the observer to monitor a good floating image even when using polarized sunglasses. When these are optically joined by the adhesive 338, no light-reflecting surface is created, and the image quality of the floating image in space is not impaired.

[0033] Commercially available depolarization elements include CosmoShine SRF (manufactured by Toyobo Co., Ltd.) and depolarization adhesive (manufactured by Nagase & Co., Ltd.). In the case of CosmoShine SRF (manufactured by Toyobo Co., Ltd.), brightness can be improved by reducing interface reflection by laminating the adhesive onto the image display device. In the case of depolarization adhesive, it is used by laminating a colorless transparent plate and the image display device via the depolarization adhesive. An image light control sheet 338 is also provided on the image emission surface of the retroreflective member 5 to eliminate ghost images that occur on both sides of the normal image of the floating image 3 due to unwanted light. In this embodiment, the retroreflective member 5 is arranged parallel to the horizontal plane in space, and the floating image 3 can be displayed at an angle of θ1 with respect to the horizontal plane. For this reason, the display surface of the image display device 1 is configured to be tilted θ1 on the opposite side of the floating image 3 with respect to the horizontal plane. Furthermore, in this embodiment, the image display device 1 is equipped with a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics.

[0034] <Example of the configuration of the third retroreflective optical system forming a spatially floating video information display system> Figure 8 shows another example of the configuration of the main components of a recursive optical system for realizing a spatially floating image information display system. This spatial image information display system is suitable for a monitor to observe the spatially floating image from diagonally above and in front. 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 having narrow-angle diffusion characteristics. The liquid crystal display panel 11 can range from small ones with a screen size of about 5 inches to large ones exceeding 80 inches.

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

[0036] To eliminate ghost images generated in the floating image 3 and obtain a high-quality floating image 3, a video light control sheet 334 may be provided on the output side of the liquid crystal panel 11 shown in Figure 12(A) to control the diffusion characteristics in unwanted directions. On the other hand, as shown in Figure 12(B), a video light control sheet 338 may also be provided on the video output surface of the retroreflective member 5 to eliminate ghost images generated on both sides of the normal image of the floating image 3 due to unwanted light. By tilting the retroreflective sheet 5 (θ2) with respect to the horizontal plane, the floating image 3 can be generated at an angle of θ1 with respect to the horizontal plane. For this reason, for example, when the configuration shown in Figure 8 is incorporated into the top of a KIOSK terminal and the floating image is displayed as an avatar at the top of the terminal, the video light is directed towards the observer's eyes, allowing for monitoring of a high-brightness floating image.

[0037] To obtain the floating image 3 in space at a desired elevation angle and position, the tilt angle θ2 of the retroreflective member 5, the tilt angle θ3 of the image display device 1, and their respective positions should be optimally designed, similar to the first and second embodiments.

[0038] <Example of the configuration of the fourth retroreflective system forming a spatially floating video information display system> Figure 9 shows the main components of another example of a recurrent optical system for realizing a floating spatial image information display system. This floating spatial image information display system is suitable for a monitor to observe floating spatial images from an oblique angle 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 having narrow-angle diffusion characteristics. The liquid crystal display panel 11 can range from small ones with a screen size of about 5 inches to large ones exceeding 80 inches.

[0039] To cause the image light from the liquid crystal display panel 11 to be obliquely incident on the retroreflective member 5 positioned directly opposite it, it is preferable to place a linear Fresnel sheet 105, as shown in Figure 10, close to the image display surface of the liquid crystal panel 11 of the image display device 1 as an image light control sheet 334, and refract the image light in the desired direction. At this time, by providing a light-shielding layer on the vertical surface of the linear Fresnel and blocking the incidence of image light from sources other than the Fresnel lens, the generation of unwanted light can be suppressed. Furthermore, by providing an anti-reflective coating on the image light incidence surface and exit surface of the linear Fresnel sheet, the generation of unwanted light can be suppressed and good characteristics can be obtained.

[0040] The image light control sheet 334, equipped with the linear Fresnel sheet 105 described above, emits light towards the retroreflective member 5. Light from a narrow-angle light source device 13, described later, is incident on the liquid crystal panel 11 to generate a narrow-angle image beam, which is then incident on the retroreflective member 5 to obtain a floating image 3. The 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 plane of symmetry. In this embodiment, since the retroreflective member 2 and the image display device 1 are positioned directly opposite each other, if a monitor looks into the retroreflective member 5 of the floating image information display device, the image displayed on the liquid crystal panel 11 overlaps with the floating image, significantly degrading the image quality of the floating image.

[0041] To prevent the aforementioned image light from overlapping with the floating image, an image light control sheet is provided on the image light emission surface of the liquid crystal panel 11. For example, Shin-Etsu Polymer Co., Ltd.'s viewing angle control film (VCF) is suitable as this image light control sheet. Its structure consists of alternating transparent silicone and black silicone layers with synthetic resin on the light input and output surfaces, forming a sandwich structure, and is expected to have the same effect as the ambient light control film in this embodiment. In this case, since the viewing angle control film (VFC) has alternating transparent silicone and black silicone layers stretched in a predetermined direction, it is preferable to tilt the stretching direction of the transparent silicone and black silicone of the image light control sheet 334 with respect to the vertical direction of the pixel arrangement direction of the liquid crystal panel 11 (θ10 in the figure), as shown in Figure 11, in order to reduce moiré patterns generated at 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, ambient light enters the retroreflective member 5 and penetrates the inside of the housing, leading to a decrease in the image quality of the floating spatial image 3. To eliminate ghost images generated in the floating spatial image 3 and obtain a high-quality floating spatial image 3, as in the second and third embodiments, an image light control sheet 334 may be provided on the output side of the liquid crystal panel 11, as shown in Figures 12(A) and (B), to control the diffusion characteristics in unwanted directions. On the other hand, 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 floating spatial image 3 due to unwanted light. By arranging the above-described structures inside the housing, ambient light is prevented from entering the retroreflective member 5, thus preventing the generation of ghost images.

[0043] <First Configuration Example of a Space-Floating Video Information Display System> Figure 13 shows a first embodiment of a spatially floating image information system using the four retroreflective optical systems described above. A retroreflective member 5 is fixed to a transparent sheet 100 using adhesive or bonding. By making the distance between the image display device 1 and the retroreflective member 5 variable, the image formation position of the spatially floating image 3 can be varied, thereby giving movement to the spatially floating image and realizing an image information display device that can display a pseudo-3D spatially floating image.

[0044] <Second Configuration Example of a Spatial Floating Video Information Display System> A second embodiment of the floating video information display system will be described with reference to Figure 14. Figure 14 shows an example in which the floating video display device 202 is incorporated into a tablet terminal. The floating video display device 202 and the flat display 200 are provided in the same housing 201, and a sensing unit 203 that covers all of the display images 204 of the flat display 200 and the floating video display 202 is provided at the starting point of the flat display 200 and the floating video 204, and is provided in the same plane as a sensing area 226. Furthermore, if there are two or more sensing areas, they may be located parallel or in front of and behind each other on the plane, or they may be located on the same plane. The floating video display device 202 and the flat display 200 may be installed side by side in the same housing 201. In this embodiment, a flat display 200 is used for explanation, but it is not limited to a flat display and any display will do. In the second configuration example, this sensing area is located at a higher position from the front to the rear of the device and has a slope. This realizes an arrangement that is easy to input. The sensing unit will be described in detail later.

[0045] In this video information display system, if the wavelength of the light source of the TOF system, which is the distance measuring system of the sensing unit 203 used, is set to a long wavelength of 900 nm or more, the system becomes less susceptible to the influence of ambient light. At this time, the user will have the illusion that they can perform the same spatial manipulation input on the display surface of the flat panel display 200 as they do on the displayed floating image 204. Therefore, spatial manipulation input can be performed without directly touching the display screen of the flat panel display 200.

[0046] Furthermore, the inventors experimentally determined how far apart the flat-panel display 200 and the sensing area 226 should be so that the operator's fingers do not touch the surface of the flat-panel display 200 when performing spatial operations based on the screen displayed on the flat-panel display 200. As a result, they experimentally found that by positioning the image of the floating spatial image 204 at a distance of 40 mm or more from the flat-panel display 200, the probability of the operator directly touching the screen of the flat-panel display 200 could be reduced to 50% or less. Moreover, by moving the distance to 50 mm or more, direct contact with the flat-panel display 200 during operation was eliminated.

[0047] Furthermore, the configuration shown in Figure 14 is not limited to tablet devices; it may also be incorporated into various display devices such as ATMs, automatic ticket vending machines, kiosk terminals, and stationary display devices.

[0048] <Third Configuration Example of a Space-Floating Video Information Display System> A third embodiment of the floating image information display system will be described with reference to Figure 15. Figure 15 shows an example in which the floating image display device 202 is incorporated into a tablet terminal. The floating image display device 202 and the flat display 200 are provided 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 floating image 204 of the 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 floating image display device 202 and the flat display 200, respectively. The first sensing area 226a and the second sensing area 226b are also located in close proximity to each other. The first sensing area and the second sensing area exist parallel to each other or in front of and behind each other on a plane. As shown in Figure 15, the first sensing area and the second sensing area may be configured to exist on the same plane. The floating spatial image display device 202 and the flat display 200 may be installed together in the same housing 201. In this embodiment, a flat display 200 is used for explanation, but it is not limited to a flat display and any display will suffice. In this embodiment, it 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.

[0049] In the third embodiment of the video information display system described above, the user is given the illusion that they can perform the same spatial manipulation input on the display surface of the flat panel display 200 as they do on the floating spatial image 204. Therefore, spatial manipulation input can be performed without directly touching the display screen of the flat panel display 200.

[0050] At this time, the prototype was evaluated using an actual device to assess finger contact with the flat display 200. The results showed that by positioning the floating image 204 at a distance of 50 mm or more from the flat display 200, the operator could perform spatial manipulation input to the video information display system without directly touching the screen of the flat display 200.

[0051] Furthermore, the configuration shown in Figure 15 is not limited to tablet devices; it may also be incorporated into various display devices such as ATMs, automatic ticket vending machines, kiosk terminals, and stationary display devices.

[0052] <Technical means for sensing spatial images> The following describes sensing technology for simulating the manipulation of floating images in order for the monitor (operator) to connect bidirectionally to the information system via the floating image display device.

[0053] In the floating video information system, by reading sensing information in conjunction with the floating video using a 2D sensor (described later), image manipulation of the displayed video becomes possible.

[0054] The following describes sensing technology for simulating the manipulation of floating images in space, as the monitor (operator) is connected bidirectionally to the information system via a floating image display device. Figure 16 is a schematic diagram illustrating the principle of the sensing technology. A distance measuring device 203 incorporating a TOF (Time of Flight) system corresponding to the floating image in space is provided. A near-infrared emitting LED (Light Emitting Diode), which is the light source, is made to emit light in synchronization with the system signal. An optical element for controlling the divergence angle is provided on the light-emitting side of the LED, and a pair of highly sensitive avalanche diodes with picosecond time resolution are used as light-receiving elements, arranged horizontally in alignment to correspond to the area. The phase Δt shifts by the time it takes for the LED, which is the light source, to emit light in synchronization with the signal from the system, to reflect off the object to be measured (the tip of the monitor's finger), and return to the light-receiving unit. The distance to the object is calculated from this time difference Δt, and together with the position information of multiple sensors arranged in parallel, the position and movement of the operator's finger are sensed as two-dimensional information. Furthermore, it is possible to realize a spatial floating information display system or spatial floating image display device that has a sensing function that minimizes false detections between the display screen of a flat panel display and the spatial floating image.

[0055] <Technical means for reducing ghost images> Technical means for realizing a high-quality spatial image display device with reduced ghost images as a spatial floating image display device will be explained with reference to Figure 12. To control the divergence angle of the image light from the liquid crystal panel 13, which is an image display element, in a desired direction, it is preferable to provide an image light control sheet 334 on the output surface of the liquid crystal panel 13. Furthermore, by providing a light emission control sheet 334 on the light emission surface or the light incidence surface or both sides of the retroreflective member, abnormal light that generates ghost images can be absorbed.

[0056] Figure 12 shows a specific method for applying the video light control sheet 334 to a spatial video display device. The video light control sheet 334 is placed on the output surface of the liquid crystal panel 335, which is a video display element. In this case, the following two methods are effective in reducing moiré patterns caused by interference between the pixels of the liquid crystal panel 13 and the pitch of the transmissive portion 336 and light-absorbing portion 337 of the video light control sheet 334.

[0057] (1) The vertical stripes generated by the light-transmitting and light-absorbing portions of the video light control sheet 334 are tilted by θ10 with respect to the pixel arrangement of the liquid crystal panel 335 (indicated as liquid crystal panel 11 in Figure 11), as shown in Figure 11.

[0058] (2) When the pixel dimensions of the liquid crystal panel 335 are A and the pitch of the vertical stripes of the image light control sheet 334 is B, this ratio (B / A) is selected from an integer multiple.

[0059] Each pixel 339 in a liquid crystal panel consists of three pixels of RGB arranged in parallel, and is generally square in shape. Therefore, it is not possible to completely suppress the occurrence of moiré patterns across the entire screen. For this reason, it was experimentally determined that the tilt θ10 shown in (1) should be optimized within a range of 5 to 25 degrees so that the moiré occurrence location can be intentionally shifted to a location where the floating image is not displayed. Although a liquid crystal panel was used as an example to discuss reducing moiré patterns, the moiré patterns that occur between the retroreflective member 5 and the image light control sheet 334 are also linear structures. As shown in Figure 4, by optimally tilting the image light control sheet with respect to the X-axis, it is possible to reduce large, low-frequency moiré patterns that are visible even to the naked eye with long wavelengths.

[0060] Figure 12(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 placed on the image light emitting surface of the liquid crystal panel 335. The image light control sheet 334 is constructed by alternately arranging light-transmitting portions 336 and light-absorbing portions 337 and is adhesively fixed to the image light emitting surface of the liquid crystal panel 335 by an adhesive layer 338.

[0061] Furthermore, as mentioned above, when using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel as the image display device 1, even if one pixel (one triplet) (A in the figure) is approximately 80 μm, if the pitch B of the image light control sheet 334, for example, consisting of a transmissive portion d2 of 300 μm and a light-absorbing portion d1 of 40 μm, is 340 μm, it can control sufficient transmission characteristics and the diffusion characteristics of image light from the image display device, which are the cause of abnormal light generation, thereby reducing ghost images that occur on both sides of the floating image in space. At this time, if the thickness of the image control sheet is 2 / 3 or more of the pitch B, the ghost reduction effect is greatly improved.

[0062] Figure 12(B) is a vertical cross-sectional view of the retroreflective member of the present invention, in which an image light control sheet 334 is placed on the image light emission surface of the retroreflective member 5. The image light control sheet 334 is constructed by alternately arranging light transmitting portions 336 and light absorbing portions 337, and is inclined with an inclination angle θ1 in accordance with the emission direction of retroreflective light. As a result, abnormal light generated due to retroreflection is absorbed, while normal reflected light is transmitted without loss.

[0063] When using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) (A in the figure) is approximately 80 μm, if, for example, the pitch B consisting of a 400 μm transmissive portion d2 and a 20 μm light-absorbing portion d1 of the retroreflective part is 420 μm, then sufficient transmission characteristics and the diffusion characteristics of the image light from the image display device, which are the cause of abnormal light generation in the retroreflective material, are controlled to reduce ghost images that occur on both sides of the floating image in space.

[0064] The aforementioned video light control sheet 334 also prevents external light from entering the space-floating video display device, thus contributing to improved reliability of the components. For example, Shin-Etsu Polymer Co., Ltd.'s viewing angle control film (VCF) is suitable as this video light control sheet. Its structure consists of alternating transparent and black silicone layers with synthetic resin on the light input and output surfaces, forming a sandwich structure, and is expected to have the same effect as the external light control film in this embodiment.

[0065] <LCD panel performance> Incidentally, in typical TFT (Thin Film Transistor) liquid crystal panels, the brightness and contrast performance differ depending on the characteristics of the liquid crystal and polarizer, depending on the direction of light emission. In the evaluation in the measurement environment shown in Figure 29, the brightness and viewing angle characteristics in the short-side (up and down) direction of the panel are superior at angles slightly deviated from the emission angle perpendicular to the panel surface (emission angle 0 degrees) (in this embodiment, +5 degrees), as shown in Figure 31. This is because, 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.

[0066] On the other hand, as shown in Figure 33, the contrast performance in the short-side (vertical) direction of the panel is best in the range of -15 degrees to +15 degrees. When combined with the brightness characteristics, the best performance is obtained when used in a range of ±10 degrees centered around 5 degrees.

[0067] Furthermore, as shown in Figure 30, the brightness and viewing angle characteristics in the longitudinal (left-right) direction of the panel are superior at an emission angle perpendicular to the panel surface (emission angle of 0 degrees). This is because, in the longitudinal (left-right) direction of the liquid crystal panel, the light twisting characteristic becomes 0 degrees when the applied voltage is at its maximum.

[0068] Similarly, as shown in Figure 32, the contrast performance in the longitudinal (left-right) direction of the panel is best in the range of -5 to -10 degrees. When combined with the brightness characteristics, the best performance is obtained when used within a range of ±5 degrees centered on -5 degrees. For this reason, the emission angle of the image light emitted from the liquid crystal panel is adjusted by the light beam direction conversion means (reflective surfaces 307, 314, etc.) provided on the light guide of the light source device 13 as described above. By inducing light into the liquid crystal panel from the direction that yields the best characteristics and modulating the light with the image signal, the image quality and performance of the image display device 1 will be improved.

[0069] To maximize the brightness and contrast characteristics of a liquid crystal panel as an image display element, the image quality of floating images can be improved by setting the incident light from the light source to the liquid crystal panel within the range described above.

[0070] <Method for controlling light source> 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, the image display device 1, which includes the light source device 13 and the liquid crystal display panel 11, emits a luminance-modulated image beam from the light source device 13 towards the retroreflective member after it has been incident on the liquid crystal panel 11 at an incident angle that maximizes the characteristics of the liquid crystal panel 11, in accordance with the image signal. At this time, in order to reduce the set volume of the floating image information display system, it is desirable to increase the degree of freedom in the arrangement of the liquid crystal panel 11 and the retroreflective member. Furthermore, in order to form a floating image at a desired position after retroreflection and ensure optimal directivity, the following technical means are used.

[0071] A transparent sheet made of optical components such as a linear Fresnel lens, as shown in Figure 10, is provided on the image display surface of the liquid crystal panel 11 as an optical direction conversion panel. By controlling the direction of the incident light beam to the retroreflective optical member while maintaining high directivity, the image formation position of the floating image in space is determined. As a result, the image light from the image display device 1 reaches the observer efficiently with high directivity (straight-line propagation), like laser light. Consequently, it is possible to display high-quality floating images in high resolution and significantly reduce the power consumption of the image display device 1, including the light source device 13.

[0072] <Example of a video display device 1> Figure 22 shows another example of the specific configuration of the video display device 1. The light source device 13 in Figure 22 is similar to the light source device in Figure 23, etc. This light source device 13 is constructed by housing LEDs, a collimator, a composite diffusion block, a light guide, etc., in a case made of, for example, plastic, and a liquid crystal display panel 11 is mounted on its top surface. In addition, an LED substrate on which semiconductor light source LED (Light Emitting Diode) elements 14a, 14b and their control circuits are mounted is attached to one side of the case of the light source device 13, and a heat sink (not shown in the figure) is attached to the outer surface of the LED substrate to cool the heat generated by the LED elements and control circuits.

[0073] Furthermore, the liquid crystal display panel frame attached to the top surface of the case is configured with a liquid crystal display panel 11 attached to the frame, and an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. In other words, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light based on control signals from a control circuit (not shown here) that constitutes an electronic device, together with LED elements 14a and 14b, which are solid light sources.

[0074] <Example 1 of the light source device for the video display device> Next, the configuration of the optical system, including the light source device housed in the case, will be described in detail with reference to Figure 21 and Figures 22(a) and (b). Figures 21 and 22 show the LEDs 14a and 14b that constitute the light source, and these are mounted in predetermined positions on the collimator 15. The collimator 15 is formed from a translucent resin such as acrylic. As shown in Figure 22(b), the collimator 15 has a cone-shaped outer surface 156 obtained by rotating a parabolic cross-section, and a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center of its apex (the side in contact with the LED substrate).

[0075] Furthermore, the central part of the flat portion of the collimator 15 (the side opposite to the apex mentioned above) has a convex lens surface 154 that protrudes outward (or a concave lens surface that is recessed inward). The parabolic surface 156 that forms the conical outer surface of the collimator 15 is set within an angle range in which light emitted from LEDs 14a and 14b in the peripheral direction can be totally reflected inside it, or a reflective surface is formed therein.

[0076] Furthermore, LEDs 14a and 14b are positioned at predetermined locations on the surface of the circuit board, substrate 102. This substrate 102 is fixed to the collimator 15 such that LEDs 14a or 14b on its surface are positioned in the center of their respective recesses 153.

[0077] With this configuration, the collimator 15, as described above, focuses the light emitted from the LED 14a or 14b, particularly the light emitted upward (to the right in the diagram) from its central portion, onto the two convex lens surfaces 157 and 154 that form the outer shape of the collimator 15, resulting in parallel light. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface that forms the outer surface of the conical shape of the collimator 15, and is also focused into parallel light. In other words, with a collimator 15 that has a convex lens in its central portion and a parabolic surface in its peripheral portion, it becomes 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.

[0078] Furthermore, a polarization conversion element 21 is provided on the light output side of the collimator 15. The polarization conversion element 21 may also be called a polarization conversion member. As is clear from Figure 22(a), this polarization conversion element 21 is constructed by combining a translucent member with a parallelogram cross-section (hereinafter referred to as a parallelogram prism) and a translucent member with a triangular cross-section (hereinafter referred to as a triangular prism), and arranging multiple such elements in an array parallel to a plane perpendicular to the optical axis of the parallel light from the collimator 15. In addition, polarizing beam splitters (hereinafter abbreviated as "PBS film") 211 and reflective films 212 are alternately provided at the interfaces between adjacent translucent members arranged in this array, and a λ / 2 phase plate 213 is provided on the output surface from which light incident on the polarization conversion element 21 and transmitted through the PBS film 211 is emitted.

[0079] The emission surface of this polarization conversion element 21 is further provided with a rectangular composite diffusion block 16, as shown in Figure 22(a). That is, the light emitted from LED 14a or 14b becomes parallel light due to the action of the collimator 15 and enters the composite diffusion block 16, where it is diffused by the emission-side texture 161 before reaching the light guide 17.

[0080] The light guide 17 is a rod-shaped member formed from a translucent resin such as acrylic, with a roughly triangular cross-section (see Figure 23(b)). As is clear from Figure 25, it comprises a light guide light incident portion (surface) 171 facing the emission surface of the composite diffusion block 16 via a first diffuser plate 18a, a light guide light reflecting portion (surface) 172 forming a slope, and a light guide light emission portion (surface) 173 facing the liquid crystal display panel 11, which is a liquid crystal display element, via a second diffuser plate 18b.

[0081] As shown in Figure 23, a magnified view of the light guide 17, the light guide's light-reflecting portion (surface) 172 has numerous reflective surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth pattern. The reflective surfaces 172a (sloping line segments in the figure) form αn (n is a natural number, for example, 1 to 130) with respect to the horizontal plane shown by the dashed line in the figure. As an example, αn is set to 43 degrees or less (but greater than or equal to 0 degrees).

[0082] The light guide incident surface 171 is formed in a curved convex shape that is inclined toward the light source. As a result, parallel light from the exit surface of the composite diffusion block 16 is diffused and incident via the first diffusion plate 18a, and as is clear from the figure, it is slightly bent (deflected) upward by the light guide incident surface 171 as it reaches the light guide light reflecting surface 172, where it is reflected and reaches the liquid crystal display panel 11 provided on the upper exit surface in the figure.

[0083] The image display device 1 described in detail above improves light utilization efficiency and its uniform illumination characteristics, while also enabling the manufacture of a compact and low-cost device, including a modularized S-polarized wave light source. In the above description, the polarization conversion element 21 was described as being installed after the collimator 15, but the present invention is not limited to this, and similar effects and benefits can be obtained by providing it in the optical path leading to the liquid crystal display panel 11.

[0084] Furthermore, the light guide's light-reflecting surface (face) 172 has numerous reflective surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth pattern. The illumination luminous beam is totally reflected on each reflective surface 172a and directed upward. In addition, a narrow-angle diffuser plate is provided on the light guide's light-emitting surface (face) 173 to adjust the directional characteristics as a substantially parallel diffused luminous beam, which is then incident on the light direction conversion panel 54 and incident on the liquid crystal display panel 11 from an oblique direction. In this embodiment, the light direction conversion panel 54 is provided between the light guide's emission surface 173 and the liquid crystal display panel 11, but the same effect can be obtained by providing it on the emission surface of the liquid crystal display panel 11.

[0085] In a typical TV application, 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 in the graph in Figure 28(A)) and the vertical direction of the screen (the display direction corresponding to the Y-axis in the graph in Figure 28(B)), as shown in the plotted curves for "Conventional Characteristics (X-direction)" in Figure 28(A) and "Conventional Characteristics (Y-direction)" in Figure 28(B).

[0086] In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel in this embodiment are as shown in the plotted curves of "Example 1 (X direction)" in Figure 28(A) and "Example 1 (Y direction)" in Figure 28(B).

[0087] In one specific example, if the viewing angle is set to 13 degrees so that the brightness is 50% of the brightness when viewed from the front (0-degree angle), this is approximately 1 / 5 of the diffusion characteristic (62-degree angle) of a typical home TV device. Similarly, in an example where the vertical viewing angles are set unevenly between the top and bottom, the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized so that the upper viewing angle is reduced to about 1 / 3 of the lower viewing angle.

[0088] By adjusting the viewing angle and other settings as described above, the amount of light in the image directed towards the user's viewing direction increases dramatically compared to conventional LCD TVs (resulting in a significant improvement in image brightness), with the brightness of the image becoming more than 50 times greater.

[0089] Furthermore, if the viewing angle characteristics are as shown in "Example 2" of Figure 28, and the viewing angle is set to 5 degrees so that the brightness of the image obtained when viewed from the front (angle 0 degrees) is 50% (brightness reduced to about half), then the angle is about 1 / 12th (narrower viewing angle) compared to the diffusion characteristics (angle 62 degrees) of a typical home TV device. Similarly, in an example where the vertical viewing angle is set equally on 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 vertical viewing angle is reduced to about 1 / 12th (narrower) compared to conventional methods.

[0090] With these settings, the brightness (light intensity) of the image directed towards the viewing direction (the direction of the user's gaze) is significantly improved compared to conventional LCD TVs, becoming more than 100 times brighter.

[0091] As described above, by narrowing the viewing angle, the amount of light beam directed towards the viewing direction can be concentrated, significantly improving the efficiency of light utilization. As a result, even when using a liquid crystal display panel for general TV applications, a significant increase in brightness can be achieved with similar power consumption by adjusting the light diffusion characteristics of the light source device, making it possible to create a video display device suitable for information display systems for bright outdoor environments.

[0092] When using a large liquid crystal display panel, the overall brightness of the screen is improved by directing the light from the edges of the screen inward so that it is directed towards the viewer when the viewer is facing the center of the screen. Figure 25 shows the convergence angle between the long side and the short side of the liquid crystal display panel, with the distance L from the liquid crystal display panel to the viewer and the panel size of the video display device (screen aspect ratio 16:10) as parameters.

[0093] The diagram shown at the top of Figure 25 assumes that the LCD display panel is oriented vertically (hereinafter also referred to as "vertical orientation") when viewing the image. In this case, the convergence angle should be set to match the shorter side of the LCD display panel (refer to the direction of arrow V in Figure 25 as appropriate). As a more specific example, as shown in the plot graph in Figure 15, for example, when using a 22" panel vertically and the viewing distance is 0.8m, setting the convergence angle to 10 degrees allows the image light from each corner (4 corners) of the screen to be effectively projected or output towards the viewer.

[0094] Similarly, when viewing a 15" panel in portrait orientation, if the viewing distance is 0.8m, a convergence angle of 7 degrees allows the image light from the four corners of the screen to be effectively directed towards the viewer. As described above, by directing the image light from the periphery of the screen towards the viewer who is in the optimal position to view the center of the screen, depending on the size of the LCD display panel and whether it is used in portrait or landscape orientation, the overall brightness of the screen can be improved.

[0095] In its basic configuration, as shown in Figure 26 above, a light source device emits a light beam with narrow-angle directional characteristics onto the liquid crystal display panel 11. By modulating the brightness in accordance with the video signal, the video information displayed on the screen of the liquid crystal display panel 11 is reflected by a retroreflective member, and the resulting floating image is displayed outdoors or indoors via a transparent member 100.

[0096] The following describes several other examples of light source devices. These alternative examples of light source devices may be used in place of the light source device in the example of the video display device described above.

[0097] When using a large liquid crystal display panel, as mentioned above, the overall brightness of the screen is improved by directing the light around the screen inward so that it faces the viewer when the viewer is directly facing the center of the screen. On the other hand, binocular parallax occurs depending on whether the viewer uses their left or right eye to view the screen. Figure 26 shows the convergence angle between the long side and short side of the liquid crystal display panel, calculated based on the position of the left and right eyes, with the distance L from the liquid crystal display panel to the viewer and the panel size of the video display device (screen aspect ratio 16:10) as parameters.

[0098] The smaller the panel size and the closer the monitoring distance, the larger the convergence angle for binocular viewing by the left and right eyes. In particular, when using small panels of 7 inches or less, the convergence angle due to binocular parallax is an important requirement. For example, for panels of 7 inches or less, the light diffusion characteristics of the light source shown in Figure 28 should be enlarged or directional characteristics should be added so that the image light is directed towards the optimal monitoring range of the system.

[0099] Furthermore, in order to obtain horizontal and vertical directional and diffusion characteristics according to the system requirements, it is necessary to optimally design the shape, surface roughness, and inclination of the reflective surface of the light guide of the aforementioned light source device 13.

[0100] <Example of a light source device 1> Next, with reference to Figure 17, another example of a light source device will be described. Figures 17(a) and (b) are diagrams in which parts of the liquid crystal display panel 11 and diffuser plate 206 are omitted in order to illustrate the light guide 311.

[0101] Figure 17 shows the state in which the LEDs 14 constituting the light source are mounted on the substrate 102. These LEDs 14 and the substrate 102 are mounted in predetermined positions relative to the reflector 15.

[0102] As shown in Figure 17(a), the LEDs 14 are arranged in a single row parallel to the side of the liquid crystal display panel 11 on the side where the reflector 300 is located (in this example, the shorter side). In the illustrated example, the reflector 300 is positioned in correspondence with this arrangement of LEDs. Note that multiple reflectors 300 may be used.

[0103] In one specific example, each reflector 300 is formed from a plastic material. In other examples, the reflector 300 may be formed from a metal material or a glass material, but since plastic material is easier to mold, plastic is used in this embodiment.

[0104] As shown in Figure 17(b), the inner surface (right side in the figure) of the reflector 300 is provided with a reflective surface (hereinafter sometimes referred to as "paraboloid") 305 that has the shape of a paraboloid cut off by the meridional plane. The reflector 300 converts the divergent light emitted from the LED 14 into approximately parallel light by reflecting it with the reflective surface 305 (paraboloid), and directs the converted light onto the end face of the light guide 311. In one specific example, the light guide 311 is a transmissive light guide.

[0105] The reflective surface of the reflector 300 is asymmetrical with respect to the optical axis of the light emitted from the LED 14. Furthermore, the reflective surface 305 of the reflector 300 is a parabolic surface as described above, and by placing the LED at the focal point of this parabolic surface, the reflected light beam is converted into approximately parallel light.

[0106] Since LED14 is a surface light source, even if it is placed at the focal point of a parabolic surface, it cannot convert the divergent light emitted from the LED into perfectly parallel light, but this does not affect the performance of the light source of the present invention. LED14 and reflector300 are a pair, and in order to ensure the predetermined performance with an LED14 mounting accuracy of ±40μm on the substrate102, the number of LEDs mounted on the substrate should be limited to a maximum of 10 or fewer, and considering mass production, it is preferable to limit it to about 5.

[0107] Although the LED 14 and reflector 300 are in close proximity in some areas, heat can be dissipated into the space on the opening side of the reflector 300, thus reducing the temperature rise of the LED. This allows the use of a plastic molded reflector 300. As a result, the shape accuracy of the reflective surface can be improved by more than 10 times compared to a glass reflector, thereby improving light utilization efficiency.

[0108] On the other hand, a reflective surface is provided on the bottom surface 303 of the light guide 311. Light from the LED 14 is converted into a parallel luminous beam by the reflector 300, reflected by the reflective surface, and emitted toward the liquid crystal display panel 11 which is positioned opposite the light guide 311. As shown in Figure 17, the reflective surface provided on the bottom surface 303 may have multiple surfaces with different inclinations in the direction of propagation of the parallel luminous beam from the reflector 300. Each of the multiple surfaces with different inclinations may have a shape that extends in a direction perpendicular to the direction of propagation of the parallel luminous beam from the reflector 300.

[0109] Furthermore, the shape of the reflective surface provided on the bottom surface 303 may be planar. 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 from the reflective surface provided on the bottom surface 303 of the light guide 311, thereby precisely adjusting the amount of light and the direction of emission of the light beam directed toward the liquid crystal display panel 11.

[0110] As shown in Figure 17, the refractive surface 314 may have multiple surfaces with different inclinations in the direction of propagation of the parallel light beam from the reflector 300. Each of the multiple surfaces with different inclinations may have a shape that extends in a direction perpendicular to the direction of propagation of the parallel light beam from the reflector 300. The inclination of these multiple surfaces refracts 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. The refractive surface 314 may also be a transmissive surface.

[0111] Furthermore, if a diffuser plate 206 is located 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 refractive surface 314. That is, the extension directions of the multiple surfaces of the refractive surface 314 with different inclinations and the extension directions of the multiple surfaces of the reflective surface provided on the bottom surface 303 with different inclinations are parallel. By making the extension directions of both parallel, the angle of light can be adjusted more effectively. On the other hand, the LED 14 is soldered to a metallic substrate 102. Therefore, the heat generated by the LED can be dissipated into the air via the substrate.

[0112] Furthermore, the reflector 300 may be in contact with the circuit board 102, but a gap may be left between them. If a gap is left, the reflector 300 is attached to the housing. Leaving a gap allows the heat generated by the LED to dissipate into the air, improving the cooling effect. As a result, the operating temperature of the LED can be reduced, thus maintaining luminous efficiency and extending its lifespan.

[0113] <Another example of a light source device 2> Next, the optical system configuration for a light source device that improves light utilization efficiency by 1.8 times using polarization conversion compared to the light source device shown in Figure 17 will be described in detail with reference to Figures 18A, 18B, 18C7C, and 18D. Note that the sub-reflector 308 is not shown in Figure 18A.

[0114] Figures 18, 18B, and 18C show the state in which the LEDs 14 constituting the light source are mounted on the substrate 102. These consist of a reflector 300 and an LED 14 as a pair of blocks, and are composed of a unit 312 having multiple blocks.

[0115] Of these, the base material 320 shown in Figure 18A(2) is the base material for the substrate 102. Generally, since the metallic substrate 102 generates heat, it is preferable to use a plastic material or the like for the base material 320 in order to insulate (heat-insulate) the heat of the substrate 102. The material and shape of the reflector 300 and the reflective surface may be the same as those of the example light source device in Figure 26.

[0116] Furthermore, the reflective surface of the reflector 300 may 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 in Figure 18A(2). In this embodiment, similar to the example in Figure 17, the reflective surface of the reflector 300 is a parabolic surface, and the center of the light-emitting surface of the LED, which is a surface light source, is positioned at the focal point of the parabolic surface.

[0117] Furthermore, due to the parabolic nature, the light emitted from the four corners of the light-emitting surface is also approximately parallel, with only the direction of emission differing. Therefore, even if the light-emitting part has a large area, if the distance between the polarization conversion element and the reflector 300 located in the subsequent stage is short, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected.

[0118] Furthermore, even if the mounting position of the LED 14 is shifted in the XY plane relative to the focal point of the corresponding reflector 300, an optical system can be realized that can mitigate the decrease in light conversion efficiency for the reasons mentioned above. Moreover, even if the mounting position of the LED 14 is scattered in the Z-axis direction, only the converted parallel light beam moves in the ZX plane, and the mounting accuracy of the LED, which is a surface light source, can be greatly reduced. In this embodiment, a reflector 300 having a reflective surface formed by meridional cutting out a part of a parabolic surface has been described, but the LED may also be placed in a part of the parabolic surface that has been cut out as a reflective surface.

[0119] On the other hand, in this embodiment, as shown in Figures 18B(1) and 18C, the divergent light from the LED 14 is reflected by the parabolic surface 321 and converted into substantially parallel light, which is then incident on the end face of the subsequent polarization conversion element 21, where the polarization conversion element 21 adjusts it to a specific polarization. This characteristic configuration allows the light utilization efficiency in this invention to be 1.8 times higher than in the example shown in Figure 26, thus realizing a highly efficient light source.

[0120] However, at this time, the approximately parallel light reflected by the parabolic surface 321 from the divergent light emitted from the LED 14 is not all uniform. Therefore, by adjusting the angular distribution of the reflected light using multiple inclined reflective surfaces 307, it is possible to direct the light toward the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11.

[0121] In this example, the LEDs are positioned so that the direction of the light (main rays) entering the reflector is approximately parallel to the direction of the light entering the liquid crystal display panel. This arrangement is easy to implement in terms of design, and placing the heat source below the light source device is preferable because it allows air to escape upwards, thus reducing the temperature rise of the LEDs.

[0122] Furthermore, as shown in Figure 18B(1), in order to improve the capture rate of divergent light from the LED 14, the light beam that cannot be captured by the reflector 300 is reflected by a sub-reflector 308 provided on a light-shielding plate 309 located above the reflector, and then reflected by the slope of the lower sub-reflector 310 to enter the effective area of ​​the subsequent polarization conversion element 21, thereby further improving the efficiency of light utilization. In other words, in this embodiment, a portion of the light reflected by the reflector 300 is reflected by the sub-reflector 308, and the light reflected by the sub-reflector 308 is reflected by the sub-reflector 310 in the direction toward the light guide 306.

[0123] The polarization conversion element 21 directs a nearly parallel light beam aligned to a specific polarization towards the liquid crystal display panel 11, which is positioned opposite the light guide 306, by the reflective shape provided on the surface of the reflective light guide 306. At this time, the light intensity 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 as described above, as well as the reflective surface shape (cross-sectional shape), inclination of the reflective surface, and surface roughness of the reflective light guide.

[0124] As for the shape of the reflective surface provided on the surface of the light guide 306, multiple reflective surfaces are arranged opposite the output 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 making the light intensity distribution of the light beam incident on the liquid crystal display panel 11 a desired value, as described above.

[0125] As shown in Figure 18B(2), the reflective surface 307 on the reflective light guide can be configured to have multiple inclinations on a single surface, thereby enabling more precise adjustment of reflected light. The configuration of the reflective surface to have multiple inclinations on a single surface may involve multiple surfaces, a multifaceted or curved surface. Furthermore, the diffusion effect of the diffuser plate 206 achieves a more uniform light intensity distribution. Light incident on the diffuser plate closer to the LED achieves a uniform light intensity distribution by changing the inclination of the reflective surface.

[0126] In this embodiment, the base material of the reflective surface 307 is a plastic material such as heat-resistant polycarbonate. Furthermore, the angle of the reflective surface 307 immediately after the λ / 2 plate 213 is ejected changes depending on the distance between the λ / 2 plate and the reflective surface.

[0127] In this embodiment as well, the LED 14 and the reflector 300 are in close proximity in some areas, but heat can be dissipated into the space on the opening side of the reflector 300, thereby reducing the temperature rise of the LED. Furthermore, the substrate 102 and the reflector 300 may be arranged upside down as shown in Figures 18A, 18B, and 18C.

[0128] However, if the circuit board 102 is placed on top, it will be close to the liquid crystal display panel 11, which may make the layout difficult. Therefore, as shown in the figure, placing the circuit board 102 on the underside of the reflector 300 (the side further from the liquid crystal display panel 11) results in a simpler configuration within the device.

[0129] A light-shielding plate 410 is provided on the light-incident surface of the polarization conversion element 21 to prevent unwanted light from entering the subsequent optical system. This configuration enables the realization of a light source device that suppresses temperature rise. In the polarizing plate provided on the light-incident surface of the liquid crystal display panel 11, the temperature rise is reduced by absorption with respect to the aligned polarization 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 polarizing plate. Furthermore, the temperature of the liquid crystal display panel 11 also rises due to absorption by the liquid crystal itself and the 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.

[0130] Figure 18D shows a modified version of the light source device shown in Figures 18B(1) and 18C. Figure 18D(1) illustrates a modified version of a part of the light source device shown in Figure 18B(1). The other components are the same as those of the light source device described in Figure 18B(1), so their illustration and repeated explanation are omitted.

[0131] First, in the example shown in Figure 18D(1), the height of the recess 319 of the subreflector 310 is adjusted to be lower than the phosphor 114 so that the principal ray of fluorescence emitted laterally (in the X-axis direction) from the phosphor 114 (see the straight line extending in the direction parallel to the X-axis in Figure 18D(1)) passes through the recess 319 of the subreflector 310. Furthermore, 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 principal ray of fluorescence emitted laterally from the phosphor 114 is incident on the effective region of the polarization conversion element 21 without being obstructed by the light-shielding plate 410.

[0132] Furthermore, the reflective surfaces of the protrusions on the top of the subreflector 310 reflect the light reflected by the subreflector 308 in order to guide the light reflected by the subreflector 308 to the light guide 306. Therefore, by adjusting the height of the protrusions 318 of the subreflector 310 so that the light reflected by the subreflector 308 is reflected and incident into the effective region of the subsequent polarization conversion element 21, the efficiency of light utilization can be further improved.

[0133] As shown in Figure 18A(2), the sub-reflector 310 is arranged to extend in one direction and has an uneven surface. Furthermore, the top of the sub-reflector 310 has one or more recesses arranged periodically along one direction. By having such an uneven surface, it is possible to configure the principal ray of fluorescence emitted laterally from the phosphor 114 to be incident on the effective region of the polarization conversion element 21.

[0134] Furthermore, the uneven shape of the sub-reflector 310 is arranged periodically at a pitch where the recesses 319 are located at the positions of the LEDs 14. In other words, each of the phosphors 114 is periodically arranged along one direction corresponding to the pitch of the recesses in the uneven shape of the sub-reflector 310. Note that if the phosphors 114 are provided on the LEDs 14, the phosphors 114 may also be described as the light-emitting part of the light source.

[0135] Furthermore, Figure 18D(2) shows a modified version of the light source device shown in Figure 18C, with a portion of it extracted. The other components are the same as those in the light source device in Figure 18C, so their illustration and repeated explanations are omitted. As shown in Figure 18D(2), the sub-reflector 310 is not required, but, similar to Figure 18D(1), the height of the light shield 410 is adjusted to be lower in the Z-axis direction relative to the position of the phosphor 114 so that the principal fluorescence rays emitted laterally from the phosphor 114 are not blocked by the light shield 410 and instead enter the effective region of the polarization conversion element 21.

[0136] Furthermore, for the light source devices shown in Figures 18A, 18B, 18C, and 18D, a side wall 400 may be provided, as shown in Figure 18A(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. If a side wall 400 is provided, it will be positioned to sandwich the space between the light guide 306 and the diffuser plate 206.

[0137] The light-emitting surface of the polarization-converting element 21, which emits light that has been polarized by the polarization-converting element 21, faces the space enclosed by the side wall 400, the light guide 306, the diffuser plate 206, and the polarization-converting element 21. Furthermore, the inner surface of the side wall 400 that covers the space from which light is emitted from the emission surface of the polarization-converting element 21 (the space to the right of the emission surface of the polarization-converting element 21 in Figure 18B(1)) is a reflective surface having a reflective film or the like. That is, the surface of the side wall 400 facing the above space has a reflective region having a reflective film. By making this portion of the inner surface of the side wall 400 a reflective surface, the light reflected by this reflective surface can be reused as light source light, thereby improving the brightness of the light source device.

[0138] Of the inner surfaces of the side wall 400, the surface that covers the polarization conversion element 21 from the side should be a surface with low light reflectivity (such as a black surface without a reflective film). This is because if reflected light is generated on the side 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 generation of stray light and light with an unexpected polarization state in the image. In addition, the side wall 400 may be configured to improve the cooling effect by making holes in a part of it that allow air to pass through.

[0139] The light source devices shown in Figures 18A, 18B, 18C, and 18D were described assuming a configuration using a 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.

[0140] <Another example of a 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 explained in detail with reference to Figures 19A(1), (2), (3), and 19B.

[0141] Figure 19A shows the state in which the LED 14 constituting the light source is mounted on the substrate 102. These are composed of a unit 328 having multiple blocks, with the collimator 18 and LED 14 forming a pair of blocks. In this embodiment, the collimator 18 is made of glass material considering heat resistance because it is close to the LED 14. The shape of the collimator 18 is the same as the shape described for the collimator 15 in Figure 18. Furthermore, by providing a light shielding plate 317 before the light is incident on the polarization conversion element 21, unwanted light is prevented or suppressed from incident on the subsequent optical system, and the temperature rise caused by such unwanted light is reduced.

[0142] The other configurations and effects of the light source shown in Figure 19A are the same as those in Figures 18A, 18B, 18C, and 18D, so a repeated explanation will be omitted. The light source device in Figure 19A may also have side walls, as described in Figures 18A, 18B, and 18C. The configurations and effects of the side walls have already been described, so a repeated explanation will be omitted.

[0143] Figure 19B is a cross-sectional view of Figure 19A(2). The configuration of the light source shown in Figure 19B is partially the same as the structure of the light source in Figure 18, and has already been explained in Figure 18, so a repeated explanation will be omitted.

[0144] <Another example of a light source device 4> Next, the light source device in Figure 23 is composed of a unit 328 having multiple blocks, each containing a collimator 18 and an LED 14 as a pair, as used in the light source device shown in Figure 19. The configuration of the optical system for the light source device using LEDs and reflective light guides 504 placed at both ends of the back of the liquid crystal display panel 11 will be explained in detail with reference to Figures 23(a), (b), and (c).

[0145] Figure 23 shows the state in which the LEDs 14 constituting the light source are mounted on the substrate 505. These are made up of units 503, which have multiple blocks in which a collimator 18 and an LED 14 form a pair. The units 503 are arranged at both ends of the back of the liquid crystal display panel 11 (in this embodiment, three units are arranged in a row in the short side direction). The light output from the units 503 is reflected by a reflective light guide 504 and incident on the liquid crystal display panel 11 (shown in Figure 23(c)) which is arranged opposite it.

[0146] As shown in Figure 23(c), the reflective light guide 504 is divided into two blocks corresponding to the units located at each end, with the central part being the highest. Since the collimator 18 is in close proximity to the LED 14, glass material is used to ensure heat resistance to the heat emitted from the LED 14. The shape of the collimator 18 is the same as that of collimator 15 in Figure 18.

[0147] Light from the LED 14 enters the polarization conversion element 501 via the collimator 18. The shape of the optical element 81 is used to adjust the distribution of light incident on the subsequent reflective light guide 504. In other words, the light intensity distribution of the light beam incident on the liquid crystal display panel 11 is optimally designed by adjusting the shape and arrangement of the collimator 18, the shape and diffusion characteristics of the optical element 81, 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.

[0148] As shown in Figure 23(b), the reflective surface shape provided on the surface of the reflective light guide 504 is such that multiple reflective surfaces are arranged opposite the output 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 region that will be the same reflective surface (i.e., the surface opposite 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 set to a desired value (optimized), as described above.

[0149] The reflective surface on the reflective light guide, similar to the reflective light guide described in Figure 18B, is configured to have multiple inclined shapes on one surface (the area that reflects light) (in the example in Figure 23, it is divided into 14 sections in the XY plane and composed of different inclined surfaces), allowing for more precise adjustment of reflected light. Furthermore, by providing a light-shielding wall 507 to prevent reflected light from leaking from the side of the light source device 13, it is possible to prevent light leakage in directions other than the desired direction (towards the liquid crystal display panel 11).

[0150] Furthermore, the units 503 positioned on the left and right of the reflective light guide 504 in Figure 23 may be replaced with the light source devices shown in Figure 18. That is, multiple light source devices (substrate 102, reflector 300, LED 14, etc.) shown in Figure 18 may be prepared, and these multiple light source devices may be arranged in positions facing each other, as shown in Figures 23(a), (b), and (c).

[0151] Figure 24(B) shows a light source device configured by arranging six of the units 503 shown in Figure 24(A) at the top and six at the bottom. As shown in the figure, the LEDs are arranged in a unit configuration of five LEDs side by side, and the desired brightness is obtained by current control with a single power supply. Therefore, as a light source device for illuminating a liquid crystal panel, the brightness of the light source can be controlled for each area illuminated by each unit. In the configuration of Figure 24, there is a reflective surface 502 that is different from the reflective surface 222, and the reflective surface 222. The reflective surface 222 has a shape like a horizontal grid or a strip with a predetermined width. The reflective surface 502 has a shape like a vertical and horizontal grid. These shapes allow for fine control of the brightness and angle of the reflected light. Therefore, even if a single light source is used in the planar display and the floating image information device shown in Figures 14 and 15, the brightness of the light source can be controlled for each illuminated area.

[0152] Figure 20 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 collimator 18, converted to a 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 planar portion of the incident surface of the diffuser plate 206 and is incident on the liquid crystal display panel 11 (see the two solid arrows in Figure 19 indicating "reflected light from the light guide").

[0153] Furthermore, of the light emitted from the polarization conversion element 21, the divergent luminous flux is totally reflected by the inclined surface of the projection on the incident surface of the diffuser plate 206 and incident on the liquid crystal display panel 11. In order to totally reflect the light emitted from the polarization conversion element 21 by the inclined surface of the projection on the diffuser plate 206, the angle of the inclined surface of the projection is changed based on the distance from the polarization conversion element 21. If the angle of the inclined surface of the projection on the side farther from the polarization conversion element 21 or farther from the LED is α, and the angle of the inclined surface of the projection on the side closer to the polarization conversion element 21 or closer to the LED is α', then α is smaller than α' (α < α'). By setting it in this way, it becomes possible to effectively utilize the polarized luminous flux.

[0154] <Diffusion characteristic control technology for video display devices> One method for adjusting the diffusion distribution of 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. In other words, by optimizing the shape of the lenticular lens, the emission characteristics of the image light (hereinafter also referred to as "image light beam") emitted in one direction from the liquid crystal display panel 11 can be adjusted.

[0155] 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 configuration of this arrangement may be adjusted. That is, by adjusting the arrangement of the microlens array, the emission characteristics in the X and Y axes of the image light beam emitted from the image display device 1 can be adjusted, and as a result, an image display device with desired diffusion characteristics can be obtained.

[0156] As further configuration examples, two lenticular lenses may be arranged in combination at the position through which the image light emitted from the image display device 1 passes, or a sheet may be provided in which a microlens array is arranged in a matrix to adjust the diffusion characteristics. With such an optical system configuration, the brightness (relative brightness) of the image light can be adjusted in the X and Y axis directions according to the reflection angle of the image light (reflection angle with the case of reflection in the vertical direction as the reference (0 degrees)).

[0157] In this embodiment, by using such a lenticular lens, it is possible to obtain superior optical characteristics that are clearly different from those of conventional characteristics, as shown in the graphs (plotted curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in Figure 27(b). Specifically, in the plotted curves of Example 1 (Y direction) and Example 2 (Y direction), the brightness characteristics in the vertical direction are made steeper, and furthermore, the balance of the directional characteristics in the vertical direction (positive and negative directions of the Y axis) is changed, thereby increasing the brightness of light due to reflection and diffusion (relative brightness).

[0158] Therefore, according to this embodiment, the image light has a narrow diffusion angle (high directivity) and consists only of specific polarization components, similar to the image light from a surface-emitting laser image source. This suppresses the ghost image that was generated by the retroreflective member when using conventional image display devices, and allows the spatially floating image due to retroreflection to be efficiently delivered to the viewer's eye.

[0159] Furthermore, the light source device described above makes it possible to provide significantly narrower directional characteristics in both the X and Y axes compared to the light diffusion characteristics of a typical liquid crystal display panel shown in Figures 28(A) and (B) (indicated as "conventional characteristics" in the figures). In this embodiment, by providing such narrow-angle directional characteristics, it is possible to realize an image display device that emits a nearly parallel image light beam directed in a specific direction and emits light with a specific polarization.

[0160] Figure 27 shows an example of the characteristics of the lenticular lens used in this embodiment. In this example, the characteristics in the X direction (vertical direction) with respect to the Z axis are shown in particular. Characteristic O shows a symmetrical brightness characteristic with the peak of the light emission direction at an angle of approximately 30 degrees upward from the vertical direction (0 degrees). Furthermore, the plotted curves of characteristics A and B shown in the graph of Figure 27 show examples of characteristics in which the image light above the peak brightness at approximately 30 degrees is focused to increase the brightness (relative brightness). As a result, in characteristics A and B, as can be seen by comparing them with the plotted curve of characteristic O, the brightness (relative brightness) of the light decreases sharply in the region where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ > 30°).

[0161] In other words, 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, which is aligned to a narrow angle by the light source device 13, can be adjusted, greatly improving the freedom of installation of the retroreflective sheet. As a result, the degree of freedom in the relationship of the image formation position of the spatially floating image that is reflected or transmitted through the window glass and formed at a desired position can be greatly improved. As a result, it becomes possible to efficiently deliver light with a narrow diffusion angle (high directivity) and only specific polarization components to the eyes of the viewer outdoors or indoors. This means that even if the intensity (brightness) of the image light from the image display device 1 is reduced, the viewer can accurately perceive the image light and obtain information. In other words, by reducing the output of the image display device 1, it becomes possible to realize an information display system with low power consumption.

[0162] The above describes in detail various embodiments and examples (i.e., specific examples) to which the present invention is applied. On the other hand, the present invention is not limited to the embodiments (specific examples) described above, but includes various modifications. For example, the embodiments described above are detailed explanations of the entire system in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace a 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. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0163] The light source device described above is not limited to floating image display devices, but can also be applied to information display devices such as HUDs, tablets, and digital signage.

[0164] In the technology according to this embodiment, by displaying high-resolution and high-brightness video information in a state of floating in space, users can, for example, operate the device without feeling anxious about contact transmission of infectious diseases. If the technology according to this embodiment is used in a system used by an unspecified number of users, it becomes possible to reduce the risk of contact transmission of infectious diseases and provide a contactless user interface that can be used without anxiety. The present invention, which provides such technology, contributes to the United Nations' Sustainable Development Goal (SDG) 3, "Good Health and Well-being."

[0165] Furthermore, in the technology according to the above-described embodiment, by reducing the divergence angle of the emitted image light and further aligning it to a specific polarization, only the normally reflected light is efficiently reflected by the retroreflective member, resulting in high light utilization efficiency and the ability to obtain bright and clear floating images in space. According to the technology according to this embodiment, it is possible to provide a highly usable non-contact user interface that can significantly reduce power consumption. The present invention, which provides such technology, contributes to the United Nations' Sustainable Development Goals (SDGs) "9 Industry, Innovation and Infrastructure" and "11 Sustainable Cities and Communities".

[0166] Furthermore, the technology according to the above-described embodiment makes it possible to form floating images in space using highly directional (straight-line) video light. In the technology according to this embodiment, 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 hidden from people facing the user, the display of highly directional video light makes it possible to provide a contactless user interface that reduces the risk of anyone other than the user looking at the floating images in space. By providing the above-described technology, the present invention contributes to "SDG 11: Make cities and human settlements inclusive, safe, resilient and sustainable," one of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Explanation of Symbols]

[0167] 1…Image display device, 2…First retroreflective member, 5…Second retroreflective member, 3…Spatial image (spatial floating image), 100…Transmissive plate, 13…Light source device, 54…Optical direction conversion panel, 105…Linear Fresnel sheet, 101…Absorbing polarizing sheet (Absorbing polarizing plate), 200…Flat-panel display, 201…Housing, 203…Sensing system, 226…Sensing area, 102…Substrate, 11, 335… Liquid crystal display panel, 206...diffuser plate, 21...polarization conversion element, 300...reflector, 213...λ / 2 plate, reflective light guide...306, reflective surface...307, 308, 310...sub-reflector, 204...space-floating image, 334...image light control sheet, 336...transmitting part, 337...light absorbing part, 81...optical element, polarization conversion element...501, unit...503, light-shielding wall...507, 401, 402...light-shielding plate, 320...substrate

Claims

1. A spatially floating image display device, A first display panel for displaying images, The light source device for the first display panel, A retroreflective member that reflects the video light from the first display panel and displays a real image floating in space in the air using the reflected light, A second display panel that displays images on its surface, The system includes a sensor that senses both touch input to the floating image in space and touch input to the image displayed on the second display panel on the same plane. A floating image display device.

2. In the spatial floating image display device according to claim 1, The sensing area of ​​the sensor includes a spatial area corresponding to the floating image and an area corresponding to the image displayed by the second display panel, and is located on the same plane. A floating image display device.

3. In the spatial floating image display device according to claim 1, The aforementioned sensor is a Time of Flight (TOF) type sensor equipped with a light source and a light receiving unit. A floating image display device.

4. In the spatial floating image display device according to claim 1, The wavelength of the light source of the sensor is 900 nm or longer. A floating image display device.

5. In the spatial floating image display device according to claim 1, The first display panel is equipped with an image light control sheet positioned in close proximity to the image display surface, The video light beam, whose direction of emission is controlled by the aforementioned video light control sheet, is reflected by the retroreflective member and then displays a floating image in space. A floating image display device.

6. In the spatial floating image display device according to claim 1, The retroreflective member is positioned at an angle with its lower part extended forward relative to the upper part of the floating image display device, and the image light is positioned to be incident on the retroreflective member at an angle. A floating image display device.

7. In the spatial floating image display device according to claim 1, The aforementioned light source device is A point or planar light source, A reflector that reflects light from the aforementioned light source, The system includes a light guide that directs light from the reflector toward the first display panel, The reflective surface of the reflector has an asymmetric shape with respect to the optical axis of the light emitted from the light source. A floating image display device.

8. In the spatial floating image display device according to claim 7, The light guide is a reflective light guide. A floating image display device.

9. In the spatial floating image display device according to claim 7, A diffuser plate that diffuses light from the light guide, The system comprises side walls positioned to sandwich the space between the light guide and the diffuser plate, A floating image display device.

10. In the spatial floating image display device according to claim 7, The reflector uses plastic, glass, or metal materials. A floating image display device.

Images