Space-floating image display device

Abstract

To provide a spatially-suspended video display device of a portable type that is compact and contributes to the sustainable development goals of "3 good health and well-being to all people" and "9 create the base for industry and technological innovation".SOLUTION: A spatially-suspended video display device comprises: a cylindrical housing with a housing upper part and a housing lower part; a window part which is provided at a part of the housing upper part, and transmits video light for forming a spatially suspended video; a video display device which is provided inside the housing upper part, and includes a light source device, and a display panel for generating and emitting video light based on the light from the light source device; a retroreflective member which is provided between the window part and the video display device, inside the housing upper part, in order to subject the video light from the video display device to retroreflection; and a battery charger accommodated in the housing lower part.SELECTED DRAWING: Figure 6C

Description

Technical Field

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

Background Art

[0002] As an example of a spatial floating image display device, Patent Document 1 discloses that "the CPU of an information processing device includes an approach direction detection unit that detects the approach direction of a user to an image formed in the air, an input coordinate detection unit that detects the coordinates at which an input is detected, an operation reception unit that processes the reception of an operation, and an operation screen update unit that updates an operation screen according to the received operation. When the user approaches the image from a predetermined direction, the CPU receives the movement of the user as an operation and executes processing according to the operation (summary excerpt)."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although the spatial floating image display device of Patent Document 1 described above can improve the operability of the spatial floating image, it does not consider improving the visual resolution or contrast of the spatial floating image, and there is a reality that further improvement of the video quality is required.

[0005] The applications of the floating image display device are wide-ranging. When used as signage (advertising billboards), its novelty—that of "images floating in space"—unlike conventional flat displays, attracts the attention of many people. Furthermore, as described in Patent Document 1, if the floating image is used as a human interface for some kind of operation, its contactless nature provides an effect of preventing viral infections transmitted through contact points such as push buttons.

[0006] On the other hand, until now, there have been no practical examples of using a floating image display device as a portable device. For example, if a floating image display device could be easily carried with one hand and users could display floating images at their preferred location and time, it could not only be used as part of an entertainment system, but floating images could also greatly expand their applications in areas such as information dissemination.

[0007] In particular, if a floating video device can be easily installed inside a vehicle such as an automobile, the floating video of a person or other object (hereinafter referred to as a concierge) can, for example, provide directions or Point of Interest (POI) information to the driver or passengers. Conversely, the driver or passengers can give instructions to the concierge, such as setting the air conditioning temperature or selecting music, using voice commands, and the concierge can respond with both video and audio. This would allow for more visually engaging, safer, and more comfortable driving assistance than simply pressing buttons.

[0008] The object of the present invention is to provide a spatial levitation image display device that can display suitable spatial levitation images with high visibility, and further, to provide a small (compact) and portable spatial levitation image display device that is suitable for use in vehicles and the like. [Means for solving the problem]

[0009] 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 as follows: The floating spatial image display device comprises a cylindrical housing having an upper part and a lower part, a window provided in a part of the upper part of the housing that transmits image light for forming a floating spatial image, an image display device provided inside the upper part of the housing that has a light source device and a display panel that generates and emits image light based on the light from the light source device, a retroreflective member provided inside the upper part of the housing between the window and the image display device that retroreflects the image light from the image display device, and a rechargeable battery housed in the lower part of the housing. [Effects of the Invention]

[0010] According to the present invention, a spatial floating image display device capable of displaying suitable and highly visible spatial floating images can be realized. Furthermore, by making the spatial floating image display device small, lightweight, and portable, it can be used anytime, anywhere. In particular, considering its use in vehicles, its shape can be installed and stored in a bottle holder or the like inside a vehicle, thereby greatly improving convenience for the user. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example of how to use a spatially floating image display device according to one embodiment of the present invention. [Figure 2] This figure shows an example of the main component configuration and retroreflective component configuration of a spatial floating image display device according to one embodiment of the present invention. [Figure 3] This figure shows the challenges of a spatially floating image display device. [Figure 4] This is a characteristic diagram showing the relationship between the surface roughness of the retroreflective material and the amount of blurring in the retroreflective image. [Figure 5] This figure shows the challenges of a spatially floating image display device. [Figure 6A]It is a diagram showing another implementation of the main configuration of the spatial floating image display device according to an embodiment of the present invention. [Figure 6B] It is a diagram showing the appearance of a spatial floating image display device that can be installed in a bottle holder according to an embodiment of the present invention. [Figure 6C] It is a diagram showing the main configuration of a spatial floating image display device that can be installed in a bottle holder according to an embodiment of the present invention. [Figure 6D] It is a diagram showing an example of the state of a spatial floating image display device installed in a bottle holder according to an embodiment of the present invention. [Figure 6E] It is a diagram showing an example of a spatial floating image. [Figure 6F] It is a diagram showing an example of the configuration of the lid of a spatial floating image display device that can be installed in a bottle holder according to an embodiment of the present invention. [Figure 7] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 8] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 9] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 10] It is an arrangement diagram showing the main part of the spatial floating image display device according to an embodiment of the present invention. [Figure 11] It is a cross-sectional view showing the configuration of the image display device that constitutes the spatial floating image display device according to an embodiment of the present invention. [Figure 12] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 13] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 14] It is a cross-sectional view showing an example of the specific configuration of the light source device. [Figure 15] It is an explanatory diagram for explaining the diffusion characteristics of the image display device. [Figure 16] It is an explanatory diagram for explaining the diffusion characteristics of the image display device. [Figure 17] It is a cross-sectional view showing the configuration of the image display device that constitutes the spatial floating image display device according to an embodiment of the present invention. [Figure 18] It is a diagram showing an example of a specific configuration of a light source device according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the disclosure of the embodiments, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification. Also, in all the drawings for explaining the present invention, those having the same function may be given the same reference numerals, and repeated explanations may be omitted.

[0013] The following embodiments relate to a spatial floating image display device capable of, for example, displaying an image by image light from a large-area video light source through a transparent member that partitions a space such as the glass of a show window, and displaying it as a spatial floating image inside or outside the space of a store. The present invention also relates to a large-scale digital signage system configured using a plurality of such spatial floating image display devices.

[0014] According to the following embodiments, for example, high-resolution video information can be displayed in a spatially floating state on the glass surface of a show window or on a light-transmissive plate material. At this time, according to the following embodiments, by making the divergence angle of the emitted video light small, that is, an acute angle, and further aligning it with a specific polarization, only regular reflected light can be efficiently reflected to the retroreflective member, so the light utilization efficiency is high, and it is possible to suppress ghost images that occur in addition to the main spatial floating image, which has been a problem in the conventional retroreflective method, and obtain a clear spatial floating image. Also, an apparatus including the light source of this embodiment can provide a novel and highly usable spatial floating image display device capable of significantly reducing power consumption. Further, for example, a spatial floating image display device capable of so-called one-way spatial floating image display that can be visually recognized outside a vehicle through a shield glass including a front glass, a rear glass, or a side glass of the vehicle can be provided.

[0015] On the other hand, conventional floating image display devices combine organic EL panels or liquid crystal display panels with retroreflective materials as high-resolution color display image sources. In conventional floating image display devices, because the image light diffuses at a wide angle, and the retroreflective part is hexahedron, in addition to the reflected light that is reflected normally, as shown in Figure 3, ghost images are generated by image light that is incident on the retroreflective material 2 (retroreflective sheet) at an oblique angle, degrading the image quality of the floating image. As the retroreflective material (retroreflective part 2a) shown in the conventional technology is hexahedron, as shown in Figure 5, in addition to the normal image R1 of the floating image, multiple ghost images are generated from the first ghost image G1 to the sixth ghost image G6. Therefore, ghost images, which are the same floating image, can be monitored by people other than the viewer, posing a major security challenge.

[0016] Furthermore, the floating image obtained by reflecting video light from a video display device with narrow-angle directivity characteristics (described later) using a retroreflective material showed blurring at each pixel of the liquid crystal display panel, in addition to the ghost image described above, as shown in Figure 4.

[0017] <Spatial Floating Image Display Device (1)> Figure 1 shows an example of how to use a spatially floating image display device according to one embodiment of the present invention. Figure 1(A) shows the overall configuration of the spatially floating image display device according to this embodiment. For example, in a store, the space is partitioned by a show window (window glass 105) which is a light-transmitting material (transparent material) such as glass. According to the spatially floating information display device of this embodiment, it is possible to transmit light through such a transparent material and display a spatially floating image in one direction to the outside of the store space. Specifically, light with a narrow-angle directional characteristic and specific polarization is emitted from the image display device 1 as an image light beam, enters the retroreflective member 2, is retroreflected and transmits through the window glass 105, and forms an aerial image (spatially floating image 3), which is a real image, on the outside of the store. In Figure 1, the inside of the window glass 105 (inside the store) is shown in the depth direction and the outside (for example, the sidewalk) is shown in the foreground. On the other hand, by providing means for reflecting specific polarization on the window glass 105, it is also possible to reflect the light and form an aerial image at a desired position inside the store.

[0018] Figure 1(B) is a block diagram showing the configuration of the video display device 1 described above. The video display device 1 includes a video display unit 1a that displays the original image of the aerial image, a video control unit 1b that converts the input video to match the resolution of the panel, a video signal receiving unit 1c that receives video signals, and a receiving antenna 1d. The video signal receiving unit 1c supports wired input signals such as USB (Universal Serial Bus) input and HDMI (High-Definition Multimedia Interface) input, as well as wireless input signals such as Wi-Fi (Wireless Fidelity), and can function as a standalone video receiver and display device, and can also display video information from tablets, smartphones, etc. Furthermore, by connecting a stick PC, it can be equipped with the capability to perform calculation processing and video analysis processing.

[0019] Figure 2 shows an example of the main components and retroreflective components of a spatially floating image display device according to one embodiment of the present invention. The configuration of the spatially floating image display device will be explained in more detail using Figure 2. As shown in Figure 2(A), a transparent member 100 such as glass is equipped with an image display device 1 that emits image light of a specific polarization at a narrow angle in an oblique direction. The image display device 1 comprises a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics.

[0020] The image light of a specific polarization from the image display device 1 is reflected by a polarization separation member 101, which has a film that selectively reflects the image light of the specific polarization and is provided on the transparent member 100, and then incident on the retroreflective member 2. In the example in Figure 2, the polarization separation member 101 is formed in a sheet shape and is adhered to the transparent member 100. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflective member 2. The image light is polarized from the specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, once when it is incident on the retroreflective member 2 and once when it is emitted. Here, the polarization separation member 101, which selectively reflects the image light of the specific polarization, has the property of transmitting the polarization of the other polarization after polarization conversion, so the image light of the specific polarization after polarization conversion passes through the polarization separation member 101. The image light that has passed through the polarization separation member 101 forms a spatially floating image 3, which is a real image, on the outside of the transparent member 100.

[0021] The light that forms the floating image 3 is a collection of light rays that converge from the retroreflective member 2 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. Thus, in the configuration shown in Figure 2, when a user views from the direction of arrow A, the floating image 3 is visible as a bright image, but when another person views from the direction of arrow B, the floating image 3 is not visible as an image at all. This characteristic is very suitable for use in systems that display images requiring high security or highly confidential images that should be hidden from people facing the user.

[0022] Depending on the performance of the retroreflective member 2, the polarization axes of the reflected image light may become uneven. In this case, some of the image light with uneven polarization axes is reflected by the polarization separation member 101 and returns to the image display device 1. This light is re-reflected on the image display surface of the liquid crystal display panel 11 that constitutes the image display device 1, potentially generating ghost images and degrading the image quality of the floating image 3. Therefore, in this embodiment, an absorbing polarizing plate 12 is provided on the image display surface of the image display device 1. The image light emitted from the image display device 1 is transmitted through the absorbing polarizing plate 12, while the reflected light returning from the polarization separation member 101 is absorbed by the absorbing polarizing plate 12. This suppresses the re-reflection and prevents image quality degradation due to ghost images in the floating image.

[0023] The polarization separation member 101 described above may be formed, for example, from a reflective polarizer or a multilayer metal film that reflects specific polarizations.

[0024] Next, Figure 2(B) shows the surface shape of a typical retroreflective member 2 manufactured by Nippon Carbide Industries Co., Ltd., which was used in this study. In the retroreflective member 2, light rays incident on the retroreflective section 2a, which consists of regularly arranged hexagonal prisms, are reflected by the walls and bottom surfaces of the hexagonal prisms and emitted as retroreflected light in the direction corresponding to the incident light, forming the normal image R1 shown in Figure 5. On the other hand, as shown in Figure 3, depending on the video light from the video display device 1 that is incident on the retroreflective member 2 at an oblique angle, ghost images (ghost images G1 to G6 in Figure 5) are formed separately from the normal image R1.

[0025] Therefore, the floating image display device of this embodiment displays a floating image 3, which is a real image, based on the image displayed on the image display device 1 of the present invention, without forming a ghost image. The resolution of this floating image 3 depends not only on the resolution of the liquid crystal display panel 11, but also largely on the outer diameter D and pitch P of the retroreflective portion 2a of the retroreflective member 2 shown in Figure 2(B). For example, when using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel 11, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective portion 2a is 240 μm and the pitch is 300 μm, then one pixel of the floating image 3 will be equivalent to 300 μm. As a result, the effective resolution of the floating image 3 is reduced to about 1 / 3. Therefore, in order to make the resolution of the floating image 3 equivalent to the resolution of the image display device 1, it is desirable to bring the diameter D and pitch P of the retroreflective portion 2a closer to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moiré patterns caused by the retroreflective member 2 and the pixels of the liquid crystal display panel 11, it is advisable to design their respective pitch ratios to be outside of integer multiples of one pixel. Furthermore, the shape should be such that none of the sides of the retroreflective portion 2a overlap with any of the sides of one pixel of the liquid crystal display panel 11.

[0026] The inventor experimentally determined the relationship between the acceptable amount of blur l of a spatially floating image and the pixel size L by creating an image display device 1 that combines a liquid crystal display panel with a pixel pitch of 40 μm and a light source with a narrow divergence angle (divergence angle of 15°) according to the present invention, in order to improve visibility. Figure 4 shows the experimental results. It was found that the amount of blur l that deteriorates visibility is preferably 40% or less of the pixel size L, and that it is hardly noticeable if it is 15% or less. In this case, the surface roughness of the reflective surface for which the amount of blur l is acceptable is an average roughness of 160 nm or less in the range of a measurement distance of 40 μm, and it was found that for an even less noticeable amount of blur l, the surface roughness of the reflective surface is preferably 120 nm or less. For this reason, it is desirable to reduce the surface roughness of the retroreflective member 2 mentioned above, and to make the surface roughness including the reflective film and its protective film that form the reflective surface less than or equal to the above values.

[0027] On the other hand, in order to manufacture the retroreflective member 2 at a low cost, it is preferable to use a roll press method for molding. Specifically, this method involves aligning the retroreflective portion 2a and shaping it on a film. In this method, the inverse shape of the shape to be shaped is formed on the roll surface, ultraviolet-curing resin is applied to a fixing base material and passed between the rolls to shape the required form, and then it is cured by irradiation with ultraviolet light to obtain the retroreflective member 2 of the desired shape.

[0028] The image display device 1 of the present invention, comprising a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics (described later), has a structurally superior system in which the possibility of images being incident on the retroreflective member 2 from an oblique angle is small, the occurrence of ghost images is prevented, and even if ghost images occur, the brightness of the ghost images is low.

[0029] <Spatial Floating Image Display Device (2)> Figure 6A shows another example (second example) of the main components of a spatially floating image display device according to one embodiment of the present invention. 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 is composed of a liquid crystal display panel of a selected size, ranging from small ones with a screen size of about 5 inches to large liquid crystal display panels exceeding 80 inches. The image light from the liquid crystal display panel 11 is reflected toward the retroreflective member 2 by a polarization separation member 101, such as a reflective polarizer.

[0030] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2, and the polarization is converted by passing the image light through the λ / 4 plate 21 twice, that is, converting a specific polarization (one polarization) to the other polarization. As a result, the other polarization after polarization conversion is transmitted through the polarization separation member 101, and a floating image 3, which is a real image, is formed and displayed on the outside of the transparent member 100. An absorbing polarizer plate 112 is provided on the external light incident surface of the transparent member 100. With the polarization separation member 101 described above, the polarization axis may become uneven due to retroreflection of light, so some of the image light is reflected back to the image display device 1. When this light is reflected again on the image display surface of the liquid crystal display panel 11 that constitutes the image display device 1, the aforementioned ghost image is generated, and the image quality of the floating image 3 is significantly reduced. Therefore, in this embodiment, an absorbing polarizer plate 12 is provided on the image display surface of the image display device 1. The absorbing polarizing plate 12 transmits the image light while absorbing the reflected light mentioned above, thereby preventing image degradation due to ghost images in the floating image 3.

[0031] To reduce the degradation of image quality caused by external light such as sunlight or illumination light from the set of this floating video display device, it is preferable to provide an absorbing polarizing plate 112 on the surface of the transparent member 100. Furthermore, since external light incident on the retroreflective member 2 generates a strong ghost image, the configuration is such that the incidence of external light is blocked by the fourth light-shielding member 25. The polarization separation member 101 is formed from a reflective polarizing plate or a metal multilayer film that reflects specific polarizations.

[0032] Between the polarization separation member 101 and the liquid crystal display panel 11, there are a second light-shielding member 23 and a third light-shielding member 24 that block oblique image light other than the normal image light (normal image R1 in Figure 5) that forms the floating image 3 in space. In addition, a first light-shielding member 22 is provided between the retroreflective member 2 and the polarization separation member 101 to block oblique image light other than the normal image light. Furthermore, as described above, a fourth light-shielding member 25 is also provided to block oblique light that generates ghost images, so that ambient light does not directly enter the retroreflective member 2. As a result, the generation of ghost images can be suppressed.

[0033] The inventors confirmed through experiments that the light-shielding effect can be enhanced by placing a third light-shielding member 24 and a second light-shielding member 23 in the space between the liquid crystal display panel 11 and the polarization separation member 101. In these experiments, the inner diameters of the second light-shielding member 23 and the third light-shielding member 24 were set to 110% of the area of ​​the region through which the normal image light beam that forms the floating image 3 passes, allowing the parts to be manufactured and assembled within the range of mechanical tolerances. To further reduce the occurrence of ghost images, setting the area of ​​the aforementioned light-shielding members to 104% or less of the region through which the normal image light beam passes suppressed the occurrence of ghost images to a level that is not a practical problem. On the other hand, the first light-shielding member 22, placed between the retroreflective member 2 and the polarization separation member 101, could further reduce the occurrence of ghost images if the distance L1 between the first light-shielding member 22 and the retroreflective member 2 was set to 50% or less of the distance between the retroreflective member 2 and the polarization separation member 101, and at 30% or less, it could be reduced to a level that is not a practical problem when viewed with the naked eye. Furthermore, by providing a fourth light-shielding member 25, a first light-shielding member 22, a second light-shielding member 23, and a third light-shielding member 24 surrounding the retroreflective member 2, the level of ghost images could be further reduced.

[0034] The cross-sectional shape of the light-shielding member in Figure 6A is approximately the same size as the effective area of ​​the light-shielding member with respect to the region through which the normal image light beam that forms the floating image 3 passes (corresponding in this embodiment to the region through which the image light beam in the absorbing polarizer 112 passes). Furthermore, the cross-sectional shape of the light-shielding member is improved by providing a beam on the inner surface, which reflects the abnormal light that forms the ghost image multiple times off the surface of the beam, thereby absorbing the abnormal light. The region through which the normal image light beam passes is reduced relative to the outer frame of the light-shielding member, and its area is made equivalent to the area of ​​the inscribed surface of the beam.

[0035] On the other hand, the shape of the retroreflective member 2 may be a concave or convex surface with a radius of curvature of 200 mm or more, rather than a planar shape directly facing the image display device 1. This allows for the ghost image to be made invisible to the viewer by moving the ghost image generated after reflection out of the viewer's field of view, even if a ghost image is generated by oblique image light reflected by the retroreflective member 2. However, a new problem arises: the amount of normally reflected light among the light reflected around the retroreflective member 2 with a radius of curvature of 100 mm or less decreases, resulting in a decrease in the ambient light intensity of the resulting floating spatial image 3. Therefore, in order to reduce the ghost image to a level that does not pose a practical problem, it is advisable to select and apply the above-mentioned technical means, or to use them in combination.

[0036] <Spatial Floating Image Display Device (3)> Figure 6B is a perspective view showing an example of the external appearance of a spatial levitation image display device (third example) according to one embodiment of the present invention. The spatial levitation image display device shown in Figure 6B has a generally cylindrical, and more specifically, cylindrical, housing 106, as shown in the figure. This spatial levitation image display device having a cylindrical housing 106 can be stored in a bottle holder (also called a drink holder; see Figure 6D below) inside a vehicle, and is a relatively small (compact) and portable spatial levitation image display device. This cylindrical shape has an axis of the cylinder extending in the height direction (corresponding to the vertical direction; Z direction in Figure 6C), and a diameter of the cylinder extending in a direction perpendicular to that (corresponding to the horizontal direction; X,Y directions in Figure 6C). This cylindrical housing 106 has a main upper housing 601 and a lower housing 602, which are integrally connected. The housing 106 houses the optical system, control circuit board, and, if necessary, a rechargeable battery.

[0037] This cylindrical housing 106 has rigidity, light-shielding properties, and waterproof properties, and has not only curved side surfaces 606 and 607, but also an upper surface 603 and a lower surface 608, which enclose the internal space of the housing.

[0038] This cylindrical housing 106 has, in some examples of its dimensions, a height of approximately 20 cm, a diameter of approximately 9 cm at the upper part 601 of the housing, and a diameter of approximately 7 cm at the lower part 602 of the housing. The size of the floating image 3 corresponds to the screen size of the liquid crystal display panel 11 and the size of the window 605, and can be, for example, 2 to 3 inches. The distance corresponding to the optical path length from the window 605 to the position where the floating image 3 is formed (distance 690 in Figure 6C) is approximately 6 cm as an example.

[0039] In this embodiment, the diameter of the upper part 601 of the housing is larger than the diameter of the lower part 602 of the housing. This configuration takes into consideration the fact that the lower part 602 of the housing is housed within the internal space of the bottle holder and the upper part 601 of the housing is exposed above the bottle holder. At the same time, this configuration allows the optical system to be housed in a larger volume in the upper part 601 of the housing than in the lower part 602. As a result, it is easier to arrange larger elements in the optical system within the upper part 601 of the housing, and it is easier to secure a longer optical path length, and a longer projection distance (distance 690 in Figure 6C) from the housing 106 (inclined surface 604) to the formation position of the floating image 3 can be secured. In addition, the screen size of the liquid crystal display panel 11 can be made larger, and correspondingly the size of the floating image 3 can be made larger. The relationship between the diameters of the lower part 602 and the upper part 601 of the housing is not limited to the above, and configurations in which the diameters of the lower part 602 and the upper part 601 of the housing are the same, or configurations in which the diameter of the upper part 601 of the housing is smaller than the diameter of the lower part 602 of the housing are also possible.

[0040] As shown in the figure, the upper part 601 of the housing has a shape in which a part of a cylinder including the top surface 603 and the side surface 606 is diagonally cut out, thereby providing a top surface 603 that is roughly a semicircular region and a sloped surface 604 that is roughly a semicircular region. A rectangular window (in other words, an opening) 605 in which a transparent member 100 or the like is placed is provided on the sloped surface 604. The window (opening) 605 is the part that emits image light to the outside. Image light from the optical system inside the housing 106 passes through this window (opening) 605 and forms a floating image 3 in space at a predetermined distance outside the housing 106, as shown in the figure. Note that the shape of the window (opening) 605 is shown as a rectangle as an example, but it is not limited to this and various shapes such as circles, ellipses, polygons, etc. are possible.

[0041] In this embodiment, the angle of the inclined surface 604 and the window portion 605 is, for example, about 45 degrees with respect to the upper surface 603 (angle α3 in Figure 6C). Correspondingly, the optical axis of the floating spatial image 3 (optical axis A3 in Figure 6C) is set to an oblique upward direction of about 45 degrees from the horizontal plane (direction W in Figure 6C). The angle and direction of the arrangement of the inclined surface 604 and the optical axis are designed to be easily directed towards the driver's face when this floating spatial image display device is installed in a bottle holder inside a vehicle (Figure 6D). The configuration of the angle and direction of the arrangement of the inclined surface 604 and the optical axis is not limited to this. For example, the angle α3 and the elevation angle of the optical axis A3 can be within a predetermined angle range (e.g., 45 degrees ± 15 degrees).

[0042] Figure 6C shows an example of the internal configuration of the portable spatial levitation image display device shown in Figure 6B. The upper part of the housing 601 mainly houses the optical system for generating the spatial levitation image 3, while the lower part of the housing 602 mainly houses the control board 610 and the rechargeable battery 611. The control board 610 and the elements of the optical system, such as the image display device 1, are interconnected by signal lines, etc.

[0043] The upper part 601 of the housing is equipped with an optical system for generating a highly visible floating image 3 in space without producing ghost images. The optical system of the upper part 601 of the housing consists of an image display device 1 (light source device 13, liquid crystal display panel 11, and a absorbing polarizer 12 in Figure 6C), a planar mirror 4, a beam splitter (in other words, a polarization separation member) 101, a retroreflective member 2 and a λ / 4 plate 21 which is a phase difference plate, a transparent member 100 and an absorbing polarizer 112.

[0044] The rechargeable battery 611 in the lower part of the housing 602 is a rechargeable battery such as a lithium-ion battery or a power supply circuit. The control board 610 is a control circuit board that constitutes the video control unit and the video / audio signal transmission / reception unit, and is equipped with a processor, memory, interfaces, etc., in other words it is the controller of this floating video display device. The control board 610 is arranged, for example, vertically in a part of the lower part of the housing 602. The control board 610 may also be equipped with a communication interface function and may send and receive data to the internet, etc.

[0045] The housing 106 has its lower part 602 housed within a bottle holder. In this levitating video display device, the housing 106 is vertically elongated and cylindrical in shape, with the optical system housed in the upper part 601 and the rechargeable battery 611, which is relatively heavier than the optical system, housed in the lower part 602. The center of gravity of the entire levitating video display device is located downwards. This allows the levitating video display device to be stably held in the bottle holder. Furthermore, this levitating video display device is relatively stable even against vibrations such as vehicle shaking.

[0046] Furthermore, in this embodiment, the height of the upper part 601 of the housing is greater than the height of the lower part 602 of the housing. The height of the upper part 601 of the housing is limited to a certain length to ensure that the device can be stably held when the lower part 602 of the housing is housed within the bottle holder.

[0047] Furthermore, an input / output terminal 5 is provided at one location on the side 606 of the upper part 601 of the housing 106. The input / output terminal 5 is connected to the control board 610. The input / output terminal 5 is a power input and signal input / output terminal, and is, for example, a USB terminal, but is not limited to this. This input / output terminal 5 is provided as a terminal for supplying power from, for example, a vehicle's cigarette lighter socket, and as a terminal for taking in various information, including video signals to be output as a floating spatial image 3 (concierge, etc.). The control board 610 supplies the video signal input from the outside through the input / output terminal 5 to the video display device 1. Alternatively, the video signal input from the outside through the input / output terminal 5 may be supplied directly to the video display device 1.

[0048] The input / output terminal 5 may be provided as multiple input / output terminals, separated into a power input terminal and a signal input / output terminal. The input / output terminal 5 may be located anywhere on the housing 106. The input / output terminal 5 may be located at one point on the top surface 603, or at one point on the side surface 607 of the lower part 602 of the housing. In this embodiment, the input / output terminal 5 on the upper part 601 of the housing can be easily accessed even when the lower part 602 of the housing is housed in a drink holder.

[0049] The input / output terminal 5 can be connected to the vehicle's power supply. External power input from the vehicle's power supply (e.g., cigarette lighter socket) is supplied to the rechargeable battery 611 through the input / output terminal 5, and the rechargeable battery 611 is charged. The rechargeable battery 611 supplies power to various parts such as the control board 610. Since this floating video device is small, a dry cell battery may be used as the rechargeable battery 611. External input information, such as input information from a car navigation system, is input to the control board 610 through the input / output terminal 5. Based on the input information, the control board 610 creates images of a concierge and corresponding audio to be displayed as the floating video 3, and controls the video display device 1, etc.

[0050] This floating video display device is also capable of voice control. Devices such as microphones and speakers may be connected to the input / output terminal 5 of the housing 106, or a car navigation system or in-vehicle system controller may be connected. The user's smartphone may also be connected. In that case, voice input and output control is possible based on the control board 610's control of the microphone, etc. That is, the control board 610 can input voice from the microphone, etc., recognize the input voice, and perform processing corresponding to the recognized predetermined instruction (e.g., display on / off). In addition, along with displaying the floating video 3, the control board 610 can read out or create voice associated with the floating video 3 (e.g., voice spoken by a concierge) using a voice synthesis function and output it to the driver, etc. through a speaker, etc. The configuration is not limited to these, and the housing 106 of the floating video display device may also be equipped with a microphone, speaker, etc.

[0051] Figure 6D shows an example of the appearance of the portable spatial levitation image display device of this embodiment installed in a cylindrical bottle holder 600H inside a vehicle. The driver or passengers inside the vehicle insert the lower part 602 of the housing of the spatial levitation image display device into the bottle holder 600H inside the vehicle and store it there. The upper part 601 of the housing protrudes above the bottle holder 600H, and the image light emitted from the window 605 forms the spatial levitation image 3.

[0052] Figure 6D shows an example where a bottle holder 600H is installed near the air conditioner, above the area where the car navigation system and other devices are located, near the center of the vehicle's dashboard 6001. This example shows a floating image display device installed in the bottle holder 600H. The orientation of the window portion 605 of the floating image display device in the bottle holder 600H (i.e., the direction of the optical axis of the image light, the orientation of the floating image 3) is adjusted to face the driver's face and eyes in the driver's seat on the right side. This orientation can be adjusted by rotating the cylindrical housing 106 inside the bottle holder 600H. When a passenger wants to view the floating image 3, the orientation of the window portion 605 should be adjusted to face the passenger's face and eyes.

[0053] Furthermore, the 600H bottle holder is not limited to those mounted in vehicles; there are also types that can be attached and detached, and this floating image display device can be installed in bottle holders in various locations, not just the example shown.

[0054] In Figure 6C, the optical system within the cylindrical housing 106 of this floating image display device is designed to fit the cylindrical housing 106, which is suitable for installation in the bottle holder 600H. The elements of the optical system are arranged to correspond to the long vertical space within the cylindrical housing 106 (especially the upper part 601 of the housing), and the optical system is designed to maximize the optical path length in the vertical direction by bending the optical path with the planar mirror 4.

[0055] In Figure 6C, the video display device 1, planar mirror 4, beam splitter 101, retroreflective member 2, and transparent member 100 are arranged in order from bottom to top in the height direction on the upper part 601 of the housing. Each element is fixed to the upper part 601 of the housing in a predetermined relationship. More specifically, for example, the beam splitter 101, retroreflective member 2, and transparent member 100 (installed in the window part 605) are arranged so that one side touches each other, or so that one side is close to each other with a predetermined gap between them. The housing 106 is longer in the height direction than in the radial direction, and the elements constituting the optical system are arranged as shown in the figure to ensure that the optical path of the video light is as long as possible in the height direction. The video display device 1, planar mirror 4, retroreflective member 2, etc. are arranged at an angle to the height direction. The video display device 1 is arranged at an angle α1. The retroreflective member 2 is arranged at an angle α2. The beam splitter 101 is arranged horizontally. The inclined surface 604 and the transparent member 100 are positioned at an angle α3. The planar mirror 4 is also positioned at an angle α4, with its plane slightly inclined relative to the vertical plane. The optical path of the image light in this optical system is the path reflected by the planar mirror 4. The optical path of the image light in this optical system is the path with the beam splitter 101 positioned between the planar mirror 4 and the retroreflective member 2.

[0056] The optical path of the image light in this optical system is, in order, from the image display device 1, through the plane mirror 4, beam splitter 101, λ / 4 plate 21, retroreflective member 2, λ / 4 plate 21, beam splitter 101, transparent member 100, and absorbing polarizer 112, to the floating image 3. Points p1 to p6 are examples of points that the image light passes through on its optical path. Point p1 is the reference point (e.g., the center point) of the image emission surface of the liquid crystal display panel 11. Point p2 is the reference point of the plane mirror 4. Point p3 is the reference point of the beam splitter 101. Point p4 is the reference point of the retroreflective member 2. Point p5 is the reference point of the transparent member 100. Point p6 is the reference point of the floating image 3. This floating image 3 is most optimally visible when viewed by the user's eye from the direction of arrow A, which corresponds to optical axis A3 (the direction directly facing the image surface).

[0057] The floating image display device shown in Figure 6B, etc., generates a floating image 3 at a predetermined distance diagonally above the housing 106. The floating image 3 may display, for example, the face of a person (concierge) who provides navigation information and POI information around the vehicle to the vehicle driver via video and audio. Figure 6E schematically shows an example of the concierge's display in the floating image 3 as seen from the driver's perspective. The floating image 3 has, for example, a rectangular area with a predetermined maximum size, and an image 3001 of the concierge is displayed within that area. The image 3001 may be a video or a still image. In addition, in conjunction with the display of the image 3001, the voice 3002 spoken by the concierge (for example, a guide for the estimated time of arrival at the destination) is output from a speaker (a vehicle speaker, or a speaker housed in the housing 106 of the floating image display device).

[0058] In Figure 6C, the video 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. Here, the liquid crystal display panel 11 is a small one with a screen size of about 2 to 3 inches. In this embodiment, the video display device 1 has a configuration in which an absorbing polarizing plate 12 is further provided on the image display surface. Alternatively, by further providing an anti-reflective film (not shown) on the image output side of the absorbing polarizing plate 12 provided on the surface of the video display device 1, the light of ghost images is transmitted and absorbed by the absorbing polarizing plate 12, thereby preventing image quality degradation due to ghost images.

[0059] Referring to Figure 6C, the internal configuration and characteristics of the portable space-floating image display device will be described in detail. The image display device 1, which consists of a liquid crystal display panel 11, an absorptive polarizing plate 12, and a light source device 13, is positioned and fixed to the housing 106 at a predetermined angle (the optical axis is at an angle α1 with respect to the horizontal plane), as shown in the figure. The light source device 13 functions as a backlight that supplies illumination light with narrow-angle diffusion characteristics to the liquid crystal display panel 11. The image light from the image display device 1 (point p1 with respect to the optical axis) is reflected on the plane mirror 4 (point p2), changes direction, and enters the beam splitter 101 (point p3). The image light then passes through the beam splitter 101 (point p3) and continues toward the retroreflective member 2 (point p4).

[0060] As will be explained later in Figures 8 and 9, the light source from the light source device 13 can be either S-polarized (perpendicularly polarized) (Figure 8) or P-polarized (parallel polarized) (Figure 9). In either case, the light source from the light source device 13 functions as the backlight for the liquid crystal display panel 11. Correspondingly, the video light emitted from the video display device 1 (liquid crystal display panel 11) (i.e., the video light modulated by the video source signal on the liquid crystal display panel 11 based on the light source) can also be either S-polarized or P-polarized. Below, we will first explain the case where the video light from the video display device 1 has the characteristics of P-polarized video light.

[0061] The image light (P-polarized) emitted from the liquid crystal display panel 11 and transmitted through the absorbing polarizer 12 initially heads towards the plane mirror 4, as shown by optical axis A1. This image light (P-polarized) is reflected on the plane mirror 4 and heads towards the beam splitter 101, as shown by optical axis A2.

[0062] The beam splitter (polarization separation member) 101 has a polarization separation function and is an element with a structure that transmits P-polarized light from the liquid crystal display panel 11, i.e., the image display device 1, which uses the light source device 13 as a backlight, but reflects (in other words does not transmit) S-polarized light. Such a beam splitter 101 is formed from a reflective polarizer or a multilayer film that reflects specific polarizations. In this embodiment, the multilayer film is a metal multilayer film.

[0063] Next, the video light (e.g., P-polarized) that has passed through the beam splitter 101 heads towards the retroreflective member 2. A λ / 4 plate 21 is provided on the light incidence surface of the retroreflective member 2. The video light (P-polarized) from the beam splitter 101, as video light (P-polarized) from the video display device 1, passes through the λ / 4 plate 21 twice: once when it is incident on the retroreflective member 2 and again when it is emitted after reflection. As a result, this video light undergoes a polarization conversion from one polarization to the other. Specifically, it is converted from P-polarized to S-polarized. As a result, the video light reflected by the retroreflective member 2 becomes video light with S-polarized characteristics (video light with different polarization characteristics than the original video light) and heads towards the beam splitter 101. This video light (S-polarized) is reflected by the beam splitter 101 and heads towards the transparent member 100, as shown by optical axis A3. The image light (S-polarized) is transmitted to the outside through the transparent member 100 and the absorbing polarizer 112 of the window section 605, generating and displaying a real image, a floating image 3, at a predetermined distance 690 outside the window section 605.

[0064] Alternatively, in the opposite case to the above embodiment, where the image light from the image display device 1 is S-polarized, the following occurs. The S-polarized image light emitted from the image display device 1 is reflected by the plane mirror 4 and directed towards the beam splitter 101. In this case, the beam splitter 101 is an element with a structure that transmits the image light (S-polarized) from the image display device 1 and reflects the P-polarized light. The image light (S-polarized) from the beam splitter 101 is polarized by reflection by the retroreflective member 2 and passing twice through the λ / 4 plate 21 to become P-polarized. This image light (P-polarized) is reflected by the beam splitter 101 and directed towards the transparent member 100, and passes through the transparent member 100, etc., to form the floating image 3.

[0065] The design of the polarization of the above-mentioned video light and beam splitter 101, etc., is possible in any of the embodiments. Furthermore, when the video light from the video display device 1 is S-polarized, there is the advantage of higher reflectivity at the planar mirror 4. When the video light from the video display device 1 is P-polarized, there is the advantage of easier viewing even when the user is wearing polarized sunglasses and viewing the floating image 3 in space.

[0066] Here, when installing the portable spatial floating image display device of this embodiment inside a vehicle, it is known that when external light (sunlight or external lighting) entering from outside the vehicle is reflected by the windshield, most of the S-polarized component of the external light (about 80%) is reflected, and the external light entering the vehicle has a large P-polarized component. Therefore, it is preferable to provide an absorbing polarizer plate 112 on the external light incident surface of the transparent member 100.

[0067] The window portion 605 transmits image light. The transparent member 100 is provided in the window portion 605 and is made of a glass plate or the like. An absorbing polarizing plate 112 is also provided on the external light incident surface of the transparent member 100. In the window portion 605 of the inclined surface 604, the transparent member 100 and the absorbing polarizing plate 112 are arranged in the portion that allows image light to pass through, while the other portion (i.e., part of the housing 106) is made of a light-shielding member to prevent external light from entering the housing 106. The size of the window portion 605 corresponds to the size of the floating image 3. In addition, in the transparent member 100 of the window portion 605, a portion (the portion that allows image light to pass through) may be formed of a transparent material, and another portion may be formed of a light-shielding member.

[0068] To reduce image quality degradation caused by external light such as sunlight and illumination from outside the housing 106 that houses the video display device 1 and other optical components, an absorbing polarizing plate 112 is provided on the outer surface of the transparent member 100. Much of the external light is absorbed by the absorbing polarizing plate 112 and does not easily enter the upper part 601 of the housing.

[0069] In the beam splitter (polarization separation member) 101, the polarization axes may become misaligned due to retroreflection of light, causing some of the image light to reflect back to the image display device 1. This light is then reflected again by the image display surface of the liquid crystal display panel 11 that constitutes the image display device 1, generating the aforementioned ghost image and significantly degrading the image quality of the floating image 3. Therefore, in this embodiment, an absorbing polarizing plate 12 is further provided on the image display surface of the image display device 1. Alternatively, an anti-reflective film (not shown) is further provided on the image output side of the absorbing polarizing plate 12 on the surface of the image display device 1, thereby transmitting the light of the ghost image and absorbing it with the absorbing polarizing plate 12, thus preventing image quality degradation due to the ghost image.

[0070] If ambient light is directly incident on the retroreflective member 2, a strong ghost image may be generated. Therefore, in this embodiment, as shown in Figure 6C, the retroreflective member 2 is positioned at an angle α2, tilted diagonally downward, and the transparent member 100 of the window portion 605 and the retroreflective member 2 (especially the retroreflective surface) are arranged in a structure where they are at a relationship of approximately 90 degrees, as shown in the figure. The main incident direction of ambient light components incident from the outside through the transparent member 100 of the window portion 605 is the same direction as the optical axis A3 of the image light (perpendicular to the surface of the transparent member 100). In this case, the retroreflective member 2 and the λ / 4 plate 21 are arranged such that the direction of the optical axis of the retroreflective member 2 (perpendicular to the surface) is at a relationship of approximately 90 degrees. In other words, the retroreflective member 2 and the λ / 4 plate 21 are arranged such that the retroreflective surface of the retroreflective member 2 and the surface of the transparent member 100 are at a relationship of approximately 90 degrees. Even when ambient light is incident on the upper part 601 of the housing, the retroreflective member 2 is positioned downward (approximately 90 degrees in Figure 6C) relative to the window 605 through which ambient light enters. Therefore, the ambient light is unlikely to directly enter the retroreflective member 2. Thus, this optical system configuration that obstructs ambient light incidence prevents the generation of strong ghost images.

[0071] Furthermore, the video display device 1 is positioned at a distance from the window 605, via the beam splitter 101 and the planar mirror 4. The video display device 1 is positioned so that the video light from optical axis A1 emitted from the video display device 1 cannot be seen through the window 605 from the direction of arrow A (optical axis A3). This further reduces the occurrence of ghost images.

[0072] In Figure 6C, the optical path length from point p1 on the video display device 1, through point p2 on the planar mirror 4, to point p3 on the beam splitter 101, is correlated with the optical path length from point p3 on the beam splitter 101 to point p6 on the floating image 3. By ensuring a sufficiently long distance 690 for forming the floating image 3 outward from the window portion 605, the floating sensation of the floating image 3 can be enhanced. Therefore, in this embodiment, as an optical system housed and arranged within a small, vertically elongated housing 106, each element is arranged at an angle, and a planar mirror 4 is provided to ensure that the optical path length from the video display device 1 to the beam splitter 101 is as long as possible.

[0073] As described above, the compact and portable spatial levitation image display device of this embodiment can be suitably installed in a bottle holder or the like inside a vehicle, and can suitably provide the driver or other users with spatial levitation images 3 such as a concierge. The cylindrical housing 106 can be suitably installed in bottle holders that are standard equipment in general vehicles, or in bottle holders that can be attached and removed. Users can easily attach and detach this spatial levitation image display device to a bottle holder or similar container or space as needed. Furthermore, by providing input / output terminals 5 on the housing 106, this spatial levitation image display device can also be powered from a power source such as the vehicle's cigarette lighter socket to the rechargeable battery 611. Therefore, this device can be charged at all times even while driving, and there is no need to worry about the battery running out even during long periods of use.

[0074] The floating image 3 formed by the floating image display device of this embodiment has directionality with respect to the viewing direction, as described above. In order for the driver and passengers in the vehicle to be able to view a bright image favorably when viewing the floating image 3, it is most desirable to view it from a direction that is directly in front of the floating image 3 (a direction aligned with the optical axis A3), as shown by arrow A in Figure 6C. In the absolute spatial coordinate system, the orientation of this floating image 3 (optical axis A3) also depends on the position and orientation of the device when it is installed in the drink holder. Furthermore, the relative orientation when the driver, etc., views the floating image 3 depends on the relationship between the position and orientation of the floating image 3 (optical axis A3) and the position and orientation of the driver's face and eyes.

[0075] Therefore, in this embodiment, assuming a bottle holder (Figure 6D) with an opening at the top in the vertical direction, the window portion 605 of the slope 604 and the corresponding optical system were designed so that when this floating image display device is installed in the bottle holder, the floating image 3 can be easily adjusted to face the driver's face and eyes. Specifically, the window portion 605 of the slope 604 is configured at an angle of approximately 45 degrees, and the optical axis A3 of the floating image 3 is set at an angle of approximately 45 degrees diagonally upward. As a result, when the driver views the floating image 3, they can easily view the floating image 3 as a bright image from directly in front of them without having to move their head or other body parts much.

[0076] If the direction of the image light emitted from the floating image display device is vertical or horizontal, the driver or other person would need to move their head or other body to match the direction of the image light, for example, to peer into the image, in order to view the floating image from directly in front of them. According to this embodiment, such a need is eliminated, and the bright floating image 3 can be viewed in a relatively natural posture even while driving.

[0077] Figure 6F shows a modified example of the above embodiment, in which a lid is provided on the housing 106. Figure 6F(A) shows that a lid 651, like a bottle cap, is provided on the upper part 601 of the housing so that the top surface 603 and the window portion 605 can be hidden in response to user operation. When the floating image display device is not in use, the lid 651 can be attached as shown in the figure to prevent scratches and dirt from adhering to the window portion 605 and to increase its strength. When the floating image display device is in use, the lid 651 is removed.

[0078] Figure 6F(B) shows another configuration example, in which the upper part 601 of the housing has a cover 652 provided on the window portion 605. The shape of the cover 652 is, for example, a flat plate. One side of this cover 652 is connected to a hinge provided on the side where the upper surface 603 and the sloped surface 604 (Figure 6B) meet, and it rotates around the hinge as an axis of rotation in response to user operation. When the floating image display device is not in use, the window portion 605 can be covered with the cover 652 as shown in the figure, which prevents scratches and dirt from adhering to the window portion 605 and also increases its strength. When the floating image display device is in use, the cover 652 is rotated as shown by the arrow and positioned on the upper surface 603, so that the window portion 605 is open.

[0079] Figure 6F(C) shows another configuration example, which includes a lid 653 provided in the upper part 601 of the housing, in a space area created by cutting out a part of the aforementioned cylinder near the window portion 605. This lid 653 may have a structure that rotates like the lid 652, but as shown in the figure, it may also have a structure that is attached to a projection or the like provided on a surface of the inclined surface 604 other than the window portion 605. When the floating image display device is not in use, the window portion 605 can be covered with the lid 653 as shown in the figure, which prevents scratches and dirt from adhering to the window portion 605 and also increases its strength. When the floating image display device is in use, the lid 653 is removed and the window portion 605 is opened. In addition to the lid, the housing 106 of the floating image display device may also be provided with a handle for carrying.

[0080] The following variations are also possible. The cylindrical housing 106 is not limited to a cylinder; it can have various cross-sectional shapes in the horizontal plane. The cross-sectional shape of the housing 106 may be, for example, rectangular (or polygonal), resulting in a cuboid-shaped housing 106. In the case of the cylindrical housing 106 of the embodiment, there is the advantage that it can be neatly fitted into a cylindrical bottle holder. In the case of a cuboid-shaped housing 106 as a variation, there are advantages such as being easy to manufacture and easy to hold.

[0081] Furthermore, in the configuration example shown in Figure 6C, the beam splitter 101, the retroreflective member 2, and the transparent member 100 of the window 605 are arranged so that their sides touch, forming a triangle, in consideration of achieving a smaller size. However, the arrangement is not limited to this, and the sides of these elements may be spaced further apart to ensure a longer optical path length.

[0082] Although the above embodiment shows a vehicle-mounted configuration, this portable spatial levitation video device is not limited to this and can be used in various locations because it is portable. For example, it can be used in a user's home, for instance, by installing it in a container other than a bottle holder. It can also be used simply by placing it on a desk or other surface without being housed in a container.

[0083] The floating image display device may use a highly directional speaker as its speaker. A highly directional speaker is a speaker that outputs highly directional sound so that the output sound can be heard only in a specific spatial area near the user's ears. The floating image display device may also be equipped with a camera and a distance measuring sensor, and may be configured to use these to detect touch operations by the user's fingers, etc., on the floating image 3 and perform predetermined processing according to the detection. The floating image display device may also detect the presence or absence of a user based on the camera image or sensor detection, or may be configured to perform user authentication by analyzing and determining the user's face, etc. Furthermore, when a card or paper is held over the floating image 3, the floating image display device may read a barcode or other code from the card or paper based on the camera image, etc., and perform processing according to the code.

[0084] As an alternative modification, similar to the light-shielding member in Figure 6A described above, a light-shielding member may be placed in the space connecting the image display device 1 and the retroreflective member 2 via the beam splitter 101 (for example, the space below the beam splitter 101) to block image light from the liquid crystal display panel 11 having a divergence angle exceeding a specific angle from entering the retroreflective member 2.

[0085] In this embodiment, the light source device 13 is preferably configured as follows (details will be described later). The light source device 13 includes a point-shaped or planar light source, optical means for reducing the divergence angle of light from the light source, polarization conversion means for aligning the light from the light source to a polarization in a specific direction, and a light guide having a reflective surface for propagating the light from the light source to the liquid crystal display panel 11. The configuration controls the light by the shape and surface roughness of the reflective surface of the light source device 13, causing the liquid crystal display panel 11 to emit an image light beam with a narrow divergence angle as image light.

[0086] Furthermore, in this embodiment, the amount of blurring in the floating image 3 is reduced and visibility is improved by reducing the surface roughness of the retroreflective surface of the retroreflective member 2 to a predetermined value or less per unit length. For example, the surface roughness of the retroreflective surface is set to 160 nm or less.

[0087] <Reflective polarizing plate> In this embodiment, if the beam splitter 101 is a reflective polarizer with a grid structure, the characteristics for light perpendicular to the polarization axis will be reduced. For this reason, a specification aligned with the polarization axis is desirable, and the light source device of this embodiment, which can emit the image light from the liquid crystal display panel 11 at a narrow angle, is an ideal light source. Similarly, the characteristics in the horizontal direction will also be reduced for light coming from an oblique angle. Considering these characteristics, the following describes an example configuration of this embodiment in which a light source (light source device 13) that can emit the image light from the liquid crystal display panel 11 at an even narrower angle is used as the backlight for the liquid crystal display panel 11. This makes it possible to provide a high-contrast floating image 3.

[0088] <Video display device> Next, the video display device 1 of this embodiment shown in Figure 1 will be described with reference to Figure 7. The video display device 1 of this embodiment includes a liquid crystal display panel 11, which is a video display element, and a light source device 13 that constitutes the light source of the liquid crystal display panel 11. In Figure 7, the light source device 13 is shown together with the liquid crystal display panel 11 as an unfolded perspective view.

[0089] As shown by the arrow 30 in Figure 7, the liquid crystal display panel 11 obtains an illumination beam from the light source device 13, which is a backlight device, that has narrow-angle diffusion characteristics, that is, strong directionality (in other words, straight-line propagation), and characteristics similar to laser light with the polarization plane aligned in one direction. It then emits modulated image light according to the input video signal. As a result, as shown in Figure 1, the emitted image light is reflected by the retroreflective member 2 and transmitted through the wind glass 105 to form a real image, which is a floating image in space 3.

[0090] Furthermore, in Figure 7, the image display device 1 is configured to include a liquid crystal display panel 11, an optical direction conversion panel 54 that controls the directional characteristics of the light beam emitted from the light source device 13, and, if necessary, a narrow-angle diffuser (not shown). That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and as indicated by the arrow 30 in Figure 7, image light with a specific polarization is emitted with its intensity modulated by the image signal. As a result, the image display device 1 projects the desired image as light with a specific polarization that has high directivity (straight-line propagation) towards the retroreflective member 2 via the optical direction conversion panel 54, and after reflection by the retroreflective member 2, it is transmitted towards the eye of a viewer outside the store space in Figure 1 to form a floating image 3 in space. A protective cover 50 (see Figures 8 and 9) may be provided on the surface of the optical direction conversion panel 54 described above.

[0091] In this embodiment, in order to improve the utilization efficiency of the light beam emitted from the light source device 13 indicated by arrow 30 in Figure 7 and to significantly reduce power consumption, the image display device 1, which includes the light source device 13 and the liquid crystal display panel 11, can project the light indicated by arrow 30 from the light source device 13 toward the retroreflective member 2 in Figure 1, and after reflection by the retroreflective member 2, the directivity can be controlled by a transparent sheet (not shown) provided on the surface of the windshield glass 105 to form a floating image 3 at a desired position. Specifically, this transparent sheet controls the imaging position of the floating image while providing high directivity with optical components such as a Fresnel lens or a linear Fresnel lens. As a result, the image light from the image display device 1 reaches an observer outside the windshield glass 105 (e.g., on the sidewalk) with high directivity (straight-line propagation) like laser light, and as a result, it is possible to display a high-quality floating image in high resolution and significantly reduce the power consumption of the image display device 1, including the LED (Light Emitting Diode) element 201 of the light source device 13.

[0092] <Example of a video display device (1)> Figure 8 shows another example of the video display device 1. Figure 8 also shows a state in which a liquid crystal display panel 11 and a light direction conversion panel 54 are placed on top of the light source device 13 of Figure 7. This light source device 13 is made of, for example, plastic, and is constructed by housing LED elements 201 and a light guide 203 inside. As shown in Figure 8, the end face of the light guide 203 has a lens shape that gradually increases in cross-sectional area toward the light receiving part in order to convert the divergent light emitted from each LED element 201 into a nearly parallel luminous beam, and has the effect of gradually decreasing the divergence angle by totally reflecting multiple times as the light propagates inside. The liquid crystal display panel 11 that constitutes the video display device 1 is attached to the upper surface of the light guide 203. In addition, an LED substrate 202 on which semiconductor light sources, LED elements 201 and control circuits for the LED elements 201 are mounted is attached to one side of the case of the light source device 13 (the left end face in Figure 8 in this example). In addition, a heat sink, which is a component for cooling the heat generated by the LED element 201 and the control circuit, may be attached to the outer surface of the LED substrate 202.

[0093] Furthermore, the frame (not shown) of the liquid crystal display panel 11, which is mounted on the top surface of the case of the light source device 13, is configured by mounting the liquid crystal display panel 11 attached to the frame, as well as FPCs (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light based on control signals from a control circuit (not shown) that constitutes the electronic device, together with the LED element 201, which is a solid light source. At this time, the generated image light has a narrow diffusion angle and consists only of specific polarization components, so a new and unprecedented image display device 1 is obtained that is similar to a surface-emitting laser image source driven by an image signal. Currently, it is technically and safely impossible to obtain a laser beam of the same size as the image obtained by the above-described image display device 1 using a laser device. Therefore, in this embodiment, for example, light similar to the surface-emitting laser image light described above is obtained from a beam of light from a general light source equipped with an LED element 201.

[0094] Next, the configuration of the optical system housed within the case of the light source device 13 will be described in detail with reference to Figures 8 and 9. Since Figures 8 and 9 are cross-sectional views, only one of the multiple LED elements 201 constituting the light source is shown. The light from these multiple LED elements 201 is converted into approximately collimated light (approximately parallel light) by the shape of the light-receiving end face 203a of the light guide 203. For this reason, the light-receiving portion of the end face of the light guide and the LED elements 201 are mounted while maintaining a predetermined positional relationship. Each of these light guides 203 is formed from a light-transmitting resin such as acrylic. The LED light-receiving surface at the end of this light guide, although not shown, has, for example, a cone-convex outer surface obtained by rotating a parabolic cross-section, and at its apex, it has a recess with a convex portion (i.e., a convex lens surface) in its center, and at the center of its planar portion, it has a convex lens surface that protrudes outward (or a concave lens surface that is recessed inward). Furthermore, the outer shape of the light-receiving section of the light guide 203 to which the LED element 201 is attached is a parabolic shape that forms a conical outer surface, and is set within an angle range in which light emitted from the LED element 201 in the peripheral direction can be totally reflected inside it, or a reflective surface is formed.

[0095] On the other hand, the LED elements 201 are each positioned at predetermined locations on the surface of the LED substrate 202, which is the circuit board for the LED elements 201. The LED substrate 202 is fixed to the LED collimator (the light-receiving end face 203a of the light guide 203) such that the LED elements 201 on its surface are each positioned in the center of the aforementioned recess.

[0096] With this configuration, the shape of the light-receiving end face 203a of the light guide 203 makes it possible to extract the light emitted from the LED element 201 as substantially parallel light, thereby improving the utilization efficiency of the generated light.

[0097] As described above, the light source device 13 is configured by attaching a light source unit, which consists of multiple LED elements 201 arranged in a row, to a light-receiving end surface 203a, which is a light-receiving part provided on the end surface of the light guide 203. The divergent light beam from the LED elements 201 is converted into approximately parallel light by the lens shape of the light-receiving end surface 203a of the light guide 203 and guided through the inside of the light guide 203 (in the direction parallel to the drawing), as shown by the arrows, and emitted toward the liquid crystal display panel 11, which is arranged approximately parallel to the light guide 203, by the light beam direction conversion means 204. By optimizing the distribution (density) of this light beam direction conversion means 204 depending on the shape of the inside or surface of the light guide 203, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled.

[0098] The aforementioned light beam direction conversion means 204 directs the light beam propagating within the light guide 203 toward the liquid crystal display panel 11, which is positioned approximately parallel to the light guide 203, by changing the shape of the surface of the light guide 203 or by providing, for example, a portion with a different refractive index inside the light guide 203. At this time, if the relative brightness ratio when comparing the brightness of the center of the screen and the periphery of the screen with the liquid crystal display panel 11 facing the center of the screen and the viewpoint positioned at the same position as the screen diagonal dimension is 20% or more, there will be no practical problems, and if it exceeds 30%, it will be an even better characteristic.

[0099] Figures 8 and 9 are cross-sectional diagrams illustrating the configuration and operation of the light source (light source device 13) of this embodiment, which performs polarization conversion, in the light source device 13 including the light guide 203 and LED element 201 described above. Figure 8 shows the case of conversion from P-polarization to S-polarization, and Figure 9 shows the case of conversion from S-polarization to P-polarization. In Figures 8 and 9, the light source device 13 consists of a light guide 203 with a light beam direction conversion means 204 provided on the surface or inside, formed by, for example, plastic, an LED element 201 as a light source, a reflective sheet 205, a phase difference plate 216, a lenticular lens, etc., and a liquid crystal display panel 11 equipped with polarizing plates on the light source light incident surface and the image light output surface is attached to the upper surface of the light source device 13 (light guide 203).

[0100] In Figure 8, a film or sheet-like reflective polarizer 49 is provided on the light source light incident surface (bottom surface) of the liquid crystal display panel 11 facing the light source device 13. This selectively reflects one side of the polarization (e.g., P-wave) 212 of the natural light beam 210 emitted from the LED element 201, reflects it off a reflective sheet 205 provided on one (lower) surface of the light guide 203, and directs it back towards the liquid crystal display panel 11. A λ / 4 plate, which is a phase difference plate 216, is provided between the reflective sheet 205 and the light guide 203, or between the light guide 203 and the reflective polarizer 49. By reflecting the light off the reflective sheet 205 and passing it through twice, the reflected light beam is converted from P-polarized to S-polarized, thereby improving the efficiency of utilizing the light source as image light. As shown by arrow 213 in Figure 8, the video light beam whose light intensity has been modulated by the video signal on the liquid crystal display panel 11 enters the retroreflective member 2 in Figure 1, and after reflection, passes through the window glass 105 to obtain a real image, a floating image 3, inside or outside the store space.

[0101] In Figure 9, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (bottom surface) of the liquid crystal display panel 11 facing the light source device 13. This selectively reflects one side of the polarization (e.g., S-wave) 211 of the natural light beam 210 emitted from the LED element 201, reflects it off a reflective sheet 205 provided on one (lower) surface of the light guide 203, and directs it back towards the liquid crystal display panel 11. A λ / 4 plate, which is a phase difference plate 216, is provided between the reflective sheet 205 and the light guide 203, or between the light guide 203 and the reflective polarizing plate 49. By reflecting the light off the reflective sheet 205 and passing it through twice, the reflected light beam is converted from S-polarized to P-polarized, thereby improving the efficiency of utilizing the light source as image light. As shown by arrow 214 in Figure 9, the video light beam whose light intensity is modulated by the video signal in the liquid crystal display panel 11 enters the retroreflective member 2 in Figure 1, and after reflection, passes through the window glass 105 to obtain a real image, a floating image 3, inside or outside the store space.

[0102] In the light source device 13 shown in Figures 8 and 9, the reflective polarizer 49, provided on the light incident surface of the opposing liquid crystal display panel 11, reflects one side of the polarization component. Therefore, the theoretically obtainable contrast ratio is the product of the reciprocal of the cross transmittance of the reflective polarizer 49 and the reciprocal of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel 11. This results in high contrast performance. In actual experiments, it was confirmed that the contrast performance of the displayed image improved by more than 10 times. As a result, high-quality images comparable to those of self-emissive organic EL displays were obtained.

[0103] <Example of a video display device (2)> Figure 10 shows another example of the specific configuration of the video display device 1. The light source device 13 in Figure 10 has a similar configuration to the light source device shown in Figure 12 and other figures, which will be described later. This light source device 13 is constructed by housing LEDs, a collimator, a composite diffusion block, and a light guide inside 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 102 on which an LED element 14, which is a semiconductor light source as shown in Figures 12 and 13, and its control circuit are mounted is attached to one side of the case of the light source device 13, and a heat sink 103, which is a component for cooling the heat generated by the LED element 14 and the control circuit, is attached to the outer surface of the LED substrate 102.

[0104] 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 403 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) that constitutes an electronic device, together with an LED element 14 which is a solid light source.

[0105] <Example of a video display device (3)> Next, another example of the specific configuration of the video display device 1 will be explained using Figure 11. The light source device of this video display device 1 converts the divergent luminous flux of natural light, which contains a mixture of P-polarization and S-polarization from the LED element 14 (e.g., LED element 14a), into a nearly parallel luminous flux using the LED collimator lens 18, and reflects it toward the liquid crystal display panel 11 using the reflective light guide 304. The reflected light is incident on a wave plate and a reflective polarizer 49 placed between the liquid crystal display panel 11 and the reflective light guide 304. A specific polarization (e.g., S-polarization) is reflected by the reflective polarizer 49, its phase is converted by the wave plate, it returns to the reflective surface, passes through the phase difference plate 216 again, and is converted into a polarization (e.g., P-polarization) that passes through the reflective polarizer 49.

[0106] As a result, natural light from the LED element 14 is aligned to a specific polarization (e.g., P polarization), incident on the liquid crystal display panel 11, and is luminance-modulated in accordance with the video signal to display an image on the panel surface. Similar to the example described above, Figure 11 shows multiple LED elements 14 (only one LED element 14a is shown in the case of a vertical cross-section) that constitute the light source, and these are mounted in predetermined positions on the LED collimator lens 18. Each of these LED collimator lenses 18 is made of a light-transmitting resin such as acrylic or glass. Similar to the example described above, the LED collimator lens 18 has a cone-convex outer surface obtained by rotating a parabolic cross-section, and at its apex, it has a recess with a convex portion (i.e., a convex lens surface) in the center. In addition, the center of its planar portion has a convex lens surface that protrudes outward (or a concave lens surface that is recessed inward). Furthermore, the parabolic surface forming the conical outer surface of the LED collimator lens 18 is set within an angle range that allows for total internal reflection of light emitted from the LED element 14 in the edge direction, or a reflective surface is formed therein.

[0107] The above configuration is the same as the light source device of the image display device shown in Figures 12 and 13. Furthermore, the light converted to approximately parallel light by the LED collimator lens 18 shown in Figure 11 is reflected by the reflective light guide 304, and a specific polarization of light is transmitted by the action of the reflective polarizer 49. The reflected light of the other polarization passes through the reflective light guide 304 again and is reflected by a reflector 271 that is placed on the side of the reflective light guide 304 opposite to the liquid crystal display panel 11. At this time, the polarization is changed by passing twice through a λ / 4 plate, which is a phase difference plate 270 placed between the reflector 271 and the reflective light guide 304, and passes through the light guide 304 again, and passes through the reflective polarizer 49 on the opposite side, i.e., the side of the liquid crystal display panel 11, to align the polarization direction and incident on the liquid crystal display panel 11. As a result, all of the light from the light source can be used, so the light utilization efficiency is doubled.

[0108] In conventional TV sets, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown as the X-axis in Figure 16(A)) and the vertical direction of the screen (shown as the Y-axis in Figure 16(B)). In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel 11 in this embodiment are such that, as shown in Example 1 of Figure 16, the viewing angle at which the brightness is 50% of that of a front view (0-degree angle) is 13 degrees, which is 1 / 5 of the conventional 62 degrees. Similarly, the vertical viewing angle is made uneven vertically, and the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized so that the upper viewing angle is about 1 / 3 of the lower viewing angle. As a result, the amount of image light directed towards the viewing direction is significantly improved compared to conventional LCD TVs, and the brightness is more than 50 times higher.

[0109] Furthermore, with the viewing angle characteristics shown in Example 2 of Figure 16, the viewing angle at which the brightness is 50% of that of a front view (0-degree angle) is set to 5 degrees, which is 1 / 12 of the conventional 62 degrees. Similarly, the vertical viewing angle is made uniform both vertically and horizontally, and the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized to reduce the viewing angle to about 1 / 12 of that of a conventional display. As a result, the amount of image light directed towards the viewing direction is significantly improved compared to conventional LCD TVs, and the brightness is more than 100 times higher. As described above, by narrowing the viewing angle, the amount of light flux directed towards the viewing direction can be concentrated, so the efficiency of light utilization is greatly improved. As a result, even when using a conventional LCD display panel for TVs, by controlling the light diffusion characteristics of the light source device, a significant improvement in brightness can be achieved with similar power consumption, and an image display device 1 that is compatible with a space-floating image display device for outdoor use can be created.

[0110] Returning to Figure 11, the basic configuration involves a light source device that emits a narrow-angle directional beam 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 the retroreflective member 2, and the resulting floating image 3 is displayed outdoors or indoors via the window glass 105 shown in Figure 1.

[0111] <Example of light source device 13 (1)> Next, a detailed example of the optical system configuration, including the light source device 13 housed within the housing 106 in Figure 6B, will be explained in detail with reference to Figures 12 and 13(A) and (B).

[0112] Figure 12 shows the LED elements 14 (14a, 14b) that constitute the light source, which are attached to the LED collimator 15 at predetermined positions. The LED collimator 15 is made of a light-transmitting resin such as acrylic. As shown in Figure 13(B), the LED collimator 15 has a cone-shaped outer surface 156 obtained by rotating a parabolic cross section, and at its apex, it has a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center. In addition, the center of its planar portion has a convex lens surface (or a concave lens surface) 154 that protrudes outward (or is recessed inward). The parabolic surface that forms the cone-shaped outer surface 156 of the LED collimator 15 is set within an angle range in which light emitted from the LED elements 14 in the peripheral direction can be totally reflected inside it, or a reflective surface is formed thereon.

[0113] Furthermore, the LED elements 14 are each positioned at predetermined locations on the surface of the LED substrate 102, which is the circuit board for the LED elements. The LED substrate 102 is fixed to the LED collimator 15 such that the LED elements 14 (14a, 14b) on its surface are each positioned in the center of the recess 153.

[0114] With this configuration, the light emitted from the LED element 14, particularly the light emitted upward from its central portion (to the right in Figure 13(B)), is focused by the two convex lens surfaces 157 and 154 that form the outer shape of the LED collimator 15, becoming parallel light. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface forming the conical outer surface 156 of the LED collimator 15, and is also focused to become parallel light. In other words, with an LED collimator 15 having a convex lens in its center and a parabolic surface around its periphery, it becomes possible to extract almost all of the light generated by the LED elements 14 (14a, 14b) as parallel light, thereby improving the utilization efficiency of the generated light.

[0115] Furthermore, a polarization conversion element 21 is provided on the light output side of the LED collimator 15. As is clear from Figure 13, 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 LED collimator 15. In addition, polarizing beam splitters (hereinafter referred to as "PBS films") 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 215 is provided on the output surface from which light incident on the polarization conversion element 21 and transmitted through the PBS films 211 is emitted.

[0116] The emission surface of this polarization conversion element 21 is further provided with a rectangular composite diffusion block 16, as shown in Figure 13(A). That is, the light emitted from the LED element 14 becomes parallel light due to the action of the LED collimator 15, enters the composite diffusion block 16, is diffused by the emission side texture 161, and then reaches the light guide 17.

[0117] As shown in Figure 13(B), the light guide 17 is a member formed in the shape of a rod with a substantially triangular cross-section from a translucent resin such as acrylic. As is clear from Figure 12, the light guide 17 comprises a light guide light incident portion (including the light guide light incident surface) 171 that faces the emission surface of the composite diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (including the light guide light reflection surface) 172 that forms a slope, and a light guide light emission portion (including the light guide light emission surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via the second diffusion plate 18b.

[0118] As shown in Figure 12 and Figure 13(B), which is a partially enlarged view, the light-reflecting portion 172 of the light guide 17 has a number of reflective surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth pattern. The reflective surfaces 172a (sloping line segments in Figure 13(B)) form αn (where n is a natural number, and in this example it is 1 to 130) with respect to the horizontal plane shown by the dashed line in the figure. As an example, here αn is set to 43 degrees or less (but greater than or equal to 0 degrees).

[0119] The light guide incident portion 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 Figure 12, it is slightly bent (deflected) upward by the light guide incident portion 171 as it reaches the light guide light reflection portion 172, where it is reflected and reaches the liquid crystal display panel 11 provided on the upper exit surface in Figure 12.

[0120] As described above, the image display device 1 improves light utilization efficiency and its uniform illumination characteristics, and can be manufactured in a compact and low-cost manner, including a modularized S-polarized wave light source device. In the above description, the polarization conversion element 21 was described as being installed after the LED collimator 15, but it is not limited to this, and similar effects and benefits can be obtained by installing it in the optical path leading to the liquid crystal display panel 11.

[0121] As described above, the light guide's light reflection section 172 has numerous reflective surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth pattern. The illumination beam is totally reflected on each reflective surface 172a and directed upward. Furthermore, a narrow-angle diffuser (not shown) is provided on the light guide's light emission section 173 to control the directional characteristics as a substantially parallel diffuse 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 section 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.

[0122] <Example of light source device 13 (2)> Figure 14 shows another example of the configuration of the optical system, such as the light source device 13. In Figure 14, as in the example in Figure 13, a plurality of LED elements 14 (14a, 14b) constituting the light source are shown (two in this example), and these are attached to the LED collimator 15 at predetermined positions. Each of these LED collimators 15 is made of a translucent resin, such as acrylic. Also, as in the example in Figure 13, the LED collimator 15 has a cone-shaped outer surface 156 obtained by rotating a parabolic cross-section, and at its apex, it has a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center. Furthermore, in the center of its planar portion, it has a convex lens surface 154 that protrudes outward (or a concave lens surface that is recessed inward). The parabolic surface forming the cone-shaped outer surface 156 of the LED collimator 15 is set within an angle range in which light emitted from the LED elements 14 in the peripheral direction can be totally reflected inside it, or a reflective surface is formed.

[0123] Furthermore, the LED elements 14 (14a, 14b) are each positioned at predetermined locations on the surface of the LED substrate 102, which is the circuit board. The LED substrate 102 is fixed to the LED collimator 15 such that the LED elements 14 (14a, 14b) on its surface are each positioned in the center of the recess 153.

[0124] With this configuration, the LED collimator 15, as described above, focuses the light emitted from the LED element 14, particularly the light emitted upward (to the right in Figure 14) from its central portion, onto the two convex lens surfaces 157 and 154 that form the outer shape of the LED collimator 15, resulting in parallel light. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface forming the conical outer surface 156 of the LED collimator 15, and is also focused into parallel light. In other words, with an LED collimator 15 that has a convex lens in its center and a parabolic surface around its periphery, it becomes possible to extract almost all of the light generated by the LED element 14 as parallel light, thereby improving the utilization efficiency of the generated light.

[0125] As shown in Figure 14(A), a light guide 170 is provided on the light output side of the LED collimator 15 via a first diffuser plate 18a. The light guide 170 is a member formed in the shape of a rod with a roughly triangular cross-section from a translucent resin such as acrylic. As is clear from Figure 14(A), the light guide 170 comprises a light guide incident portion (including the incident surface) 171 that faces the output surface of the composite diffusion block 16 via the first diffuser plate 18a, a light guide light reflection portion (including the light guide light reflection surface) 172 that forms a slope, and a light guide light output portion (including the light guide light output surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via a reflective polarizer plate 200.

[0126] If, for example, a reflective polarizer 200 is selected that has the characteristic of reflecting P-polarized light and transmitting S-polarized light, it will reflect P-polarized light from the natural light emitted from the LED element 14, which is the light source, pass through the λ / 4 plate 172c provided in the light guide light reflecting section 172 shown in Figure 14(B), be reflected by the reflective surface 172d, and pass through the λ / 4 plate 172c again to be converted to S-polarized light, so that all the light beam incident on the liquid crystal display panel 11 is unified to S-polarized light.

[0127] Similarly, if a reflective polarizer 200 is selected that has the characteristic of reflecting S-polarized light and transmitting P-polarized light, the S-polarized light from the natural light emitted from the LED element 14, which is the light source, will be reflected, pass through the λ / 4 plate 172c provided in the light guide light reflecting section 172 shown in Figure 14(B), be reflected by the reflective surface 172d, and then pass through the λ / 4 plate 172c again to be converted to P-polarized light. As a result, all the light beam incident on the liquid crystal display panel 52 will be unified into P-polarized light. Polarization conversion can be achieved with the configuration described above as well.

[0128] <Example of light source device 13 (3)> Using Figure 11, another example of the configuration of the optical system, such as a light source device, will be explained. In the third example, as shown in Figure 11, the divergent luminous flux of natural light from the LED substrate 102, which contains a mixture of P-polarized and S-polarized light, is converted into a nearly parallel luminous flux by the LED collimator lens 18 and reflected toward the liquid crystal display panel 11 by the reflective light guide 304. The reflected light is incident on a reflective polarizer 206 placed between the liquid crystal display panel 11 and the reflective light guide 304. A specific polarization (e.g., S-polarization) is reflected by the reflective polarizer 206, passes through the surface connecting the reflective surfaces of the light guide 304, is reflected by a reflector 271 placed facing the opposite side of the light guide 304, undergoes polarization conversion by passing through a phase plate (λ / 4 wave plate) 270 twice, passes through the light guide and the reflective polarizer, is incident on the liquid crystal display panel 11, and is modulated into image light. At this time, by aligning the specific polarization with the polarization-converted polarization plane, the light utilization efficiency becomes twice that of normal, and the polarization degree (extinction ratio) of the reflective polarizer is also incorporated into the extinction ratio of the entire system. Therefore, by using the light source device of this embodiment, the contrast ratio of the information display system is greatly improved.

[0129] As a result, natural light from the LEDs is aligned to a specific polarization (e.g., P polarization). In Figure 11, as in the example described above, multiple LED elements 14 (only one is shown because it is a vertical cross-section) constituting the light source are provided and are attached to the LED collimator lens 18 at predetermined positions. Each of these LED collimator lenses 18 is made of a light-transmitting resin such as acrylic or glass. As in the example described above, the LED collimator lens 18 has a cone-convex outer surface obtained by rotating a parabolic cross-section, and at its apex, it has a recess with a convex portion (i.e., a convex lens surface) in the center. In addition, the center of its planar portion has a convex lens surface that protrudes outward (or a concave lens surface that is recessed inward). The parabolic surface that forms the cone-shaped outer surface of the LED collimator lens 18 is set within an angle range in which light emitted from the LED collimator lens 18 in the peripheral direction can be totally reflected inside it, or a reflective surface is formed.

[0130] Furthermore, the LED elements 14 are each positioned at predetermined locations on the surface of the LED substrate 102, which is the circuit board for the LED elements. The LED substrate 102 is fixed to the LED collimator lens 18 such that the LEDs on its surface are each positioned in the center of their respective recesses.

[0131] With this configuration, the light emitted from the LED element 14, particularly the light emitted from its central portion, is focused by the two convex lens surfaces forming the outer shape of the LED collimator lens 18, becoming parallel light. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface forming the conical outer surface of the LED collimator lens 18, and is also focused, becoming parallel light. In other words, with an LED collimator lens 18 having a convex lens in its center and a parabolic surface around its periphery, it becomes possible to extract almost all of the light generated by the LED element 14 as parallel light, thereby improving the utilization efficiency of the generated light.

[0132] <Example of light source device 13 (4)> Furthermore, Figure 17 illustrates another example of the configuration of the optical system, such as a light source device. Two optical sheets 207 are used on the light output side of the LED collimator lens 18 to convert the diffusion characteristics in the vertical and horizontal directions as shown in the drawing, and the light from the LED collimator lens 18 is incident between the two optical sheets 207 (also called diffusion sheets or diffusion films). When a single optical sheet 207 is used, the vertical and horizontal diffusion characteristics are controlled by the fine shape of the front and back surfaces. Alternatively, multiple optical sheets 207 may be used to share the function. The diffusion angle of the light from the LED collimator lens 18 in the vertical direction of the screen is matched to the width of the vertical surface of the reflective surface of the optical sheet 207, and in the horizontal direction, the number of LED elements 14 and the divergence angle from the optical elements 107 should be optimally designed as design parameters so that the diffusion angle in the vertical direction of the light from the LED collimator lens 18 is matched to the width of the vertical surface of the reflective surface of the optical sheet 207, and the surface density of the light beam emitted from the liquid crystal display panel 11 is uniform. In other words, in this embodiment, the diffusion characteristics are controlled by the surface shapes of multiple diffusion sheets instead of a light guide. In this embodiment, polarization conversion is performed in the same manner as in Example 3 of the light source device described above. Furthermore, a polarization conversion element may be provided between the LED collimator lens 18 and the optical sheet 207 to perform polarization conversion before the light source light is incident on the optical sheet 207.

[0133] If the aforementioned reflective polarizer 206 is selected to have the characteristic of reflecting S-polarized light and transmitting P-polarized light, it will reflect S-polarized light from the natural light emitted from the LED element, which is the light source, pass through the phase difference plate 270, be reflected by the reflective surface 272, and pass through the phase difference plate 270 again to be converted to P-polarized light before being incident on the liquid crystal display panel 11. The thickness of this phase difference plate 270 needs to be selected to an optimal value depending on the angle of incidence of the light rays onto the phase difference plate, and the optimal value exists in the range of λ / 16 to λ / 4.

[0134] <Example of light source device 13 (5)> Using Figure 18, another example of the optical system configuration of the light source device 13 is explained. As shown in Figure 18(C), a polarization conversion element 21 is placed on the light output side of the LED collimator lens 18. Natural light from the LED element 14 (e.g., LED element 14c) is then incident on an optical element 81 that controls the diffusion characteristics by aligning the polarization to a specific level. By controlling the diffusion characteristics in the vertical and horizontal directions of the diagram, the light distribution characteristics toward the reflective surface of the reflective light guide 220 are optimized. As shown in Figure 18(B), an uneven pattern 222 is provided on the surface of the reflective light guide 220, and the light is reflected toward an image display device (not shown) placed on the opposite surface of the reflective light guide 220 to obtain the desired diffusion characteristics. The arrangement accuracy of the LED element 14 and the LED collimator lens 18 of the light source greatly affects the efficiency of the light source, so an optical axis accuracy of about 50 μm is usually required. Therefore, as a countermeasure against the deterioration of mounting accuracy due to the expansion of the LED collimator lens 18 caused by the heat generated by the LED, the inventor mitigated the deterioration of mounting accuracy by using multiple or a single unit in the light source device, with the structure of the light source unit 223 being an integrated unit of several LED elements 14 and the LED collimator lens 18.

[0135] In the embodiment shown in Figures 18(A), 18(B), and 18(C), multiple light source units 223, each integrating an LED element 14 and an LED collimator lens 18, are incorporated at both ends of the reflective light guide 220 in the direction of its long side (three on each side in the embodiment of Figure 18), thereby achieving uniform brightness of the light source device. Multiple uneven patterns 222, substantially parallel to the light source unit, are formed on the reflective surface 220a of the light guide 220, and even within a single uneven pattern 222, the surface forms a polyhedron, allowing for high-precision control of the amount of light incident on the image display device. In this embodiment, the shape of the reflective surface was described as an uneven pattern 222, but it may also be a pattern in which triangular surfaces, corrugated surfaces, etc., are arranged regularly or irregularly, and the light distribution pattern from the light guide 220 to the image display device can be controlled by the surface shape. Furthermore, a light-shielding wall 224 is provided on the side of the light guide 220 to prevent light controlled by the LED collimator lens 18 from leaking out of the light source device 13, and the LED element 14 is designed with a metal substrate 225 to enhance heat dissipation.

[0136] <Lenticular Sheet> The following describes the function of the lenticular lens in controlling the diffusion characteristics of the light emitted from the video display device 1 described above. By optimizing the lens shape of the lenticular lens, it becomes possible to efficiently obtain a floating image 3 in space by transmitting or reflecting the light emitted from the video display device 1 through the wind glass 105. Specifically, by providing a sheet that controls the diffusion characteristics of the video light from the video display device 1 by combining two lenticular lenses or arranging a microlens array in a matrix, the brightness (relative brightness) of the video light can be controlled in the X and Y axis directions according to its reflection angle (0 degrees in the vertical direction). In this embodiment, such a lenticular lens makes the brightness characteristics in the vertical direction steeper compared to conventional methods, as shown in Figure 16(B). Furthermore, by changing the balance of the directional characteristics in the vertical direction (positive and negative directions of the Y axis), the brightness (relative brightness) of the light due to reflection and diffusion can be increased. These effects result in image light with a narrow diffusion angle (in other words, high directivity) and containing only specific polarization components, similar to image light from a surface-emitting laser image source. This suppresses ghost images that were generated by retroreflective materials when using conventional image display devices, and efficiently controls the delivery of a floating image in space via retroreflection to the viewer's eye.

[0137] Furthermore, the aforementioned light source devices enable 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 16(A) and (B) (indicated as "conventional" in the figures). This makes it possible to realize a video display device that emits light with a specific polarization, emitting an image light beam nearly parallel to a specific direction.

[0138] Figure 15 shows an example of the characteristics of the lenticular lens used in this embodiment. In this example, the characteristics in the X-axis (vertical direction) 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 (0 degrees). Characteristics A and B further 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, the brightness (relative brightness) of the light decreases sharply at angles exceeding 30 degrees compared to characteristic O.

[0139] 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 2, the emission angle and viewing angle of the image light, which is aligned to a narrow angle by the light source device 13,230, can be controlled, and the degree of freedom in the installation of the retroreflective member 2 can be greatly improved. As a result, the degree of freedom in the relationship of the image formation position of the floating image 3, which is reflected or transmitted through the window glass 105 in Figure 1 and formed at a desired position, can be greatly improved. As a result, the light can be efficiently delivered to the eyes of an outdoor or indoor viewer as light with a narrow diffusion angle (high directivity) and containing only specific polarization components. 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, a floating image display device with low power consumption can be realized.

[0140] Although various embodiments have been described in detail above, the present invention is not limited to the embodiments described above and includes various modifications. For example, the above embodiments describe the entire system in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to having all the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments 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.

[0141] In this embodiment, the technology displays high-resolution and high-brightness video information in a floating state, allowing users to operate the system without feeling anxious about contact transmission of infectious diseases. By using this technology in systems used by a large number of users, it is possible to reduce the risk of contact transmission of infectious diseases and provide a contactless user interface that can be used without anxiety. This contributes to the United Nations' Sustainable Development Goal (SDG) 3, "Ensure healthy lives and promote well-being for all." Furthermore, in this embodiment, by reducing the divergence angle of the emitted video light and aligning it to a specific polarization, only the correct reflected light is efficiently reflected by the retroreflective material, resulting in high light utilization efficiency and enabling the acquisition of bright, clear floating images. According to this embodiment, it is possible to provide a highly usable contactless user interface that significantly reduces power consumption. This contributes to the United Nations' Sustainable Development Goal (SDG) 9, "Build resilient infrastructure, foster inclusive and sustainable industrialization and promote sustainable innovation." [Explanation of Symbols]

[0142] 1: Video display device, 2: Retroreflective material, 3: Space-floating image, 4: Planar mirror, 5: Input / output terminal, 11: Liquid crystal display panel, 12: Absorbing polarizer, 13: Light source device, 21: λ / 4 plate, 100: Transparent material, 101: Beam splitter (polarization separation material), 106: Housing, 112: Absorbing polarizer, 601: Top of housing, 602: Bottom of housing, 603: Top surface, 604: Sloping surface, 605: Window section, 606: Side, 607: Side, 608: Bottom surface, 610: Control board, 611: Rechargeable battery.

Claims

1. A spatial floating image display device that forms a spatial floating image, A cylindrical housing having an upper part and a lower part, A window portion is provided in a part of the upper part of the housing, which transmits light for forming the floating image in space, An image display device is provided inside the upper part of the housing and has a light source device and a display panel that generates and emits image light based on the light from the light source device. Inside the upper part of the housing, a retroreflective member is provided in the optical path through which the video light output from the video display device reaches the window, and which retroreflects the video light from the video display device. Inside the upper part of the housing, a polarization separation member is provided between the window and the image display device, which reflects the image light from the retroreflective member toward the window. A planar mirror is placed in the space connecting the image display device and the polarization separation member, and reflects the image light of a specific polarization from the image display device toward the polarization separation member. The housing includes a rechargeable battery housed in the lower part of the housing, A floating image display device.

2. In the spatial floating image display device according to claim 1, The lower part of the housing is housed in a control unit which has a control board, The control board is located below the video display device. A floating image display device.

3. In the spatial floating image display device according to claim 1, The aforementioned housing is equipped with a microphone, The control unit receives audio input from the microphone, reads out and outputs audio associated with the floating image in space, and performs processing corresponding to predetermined instructions. A floating image display device.

4. In the spatial floating image display device according to claim 1, The aforementioned enclosure has a speaker installed inside, The speaker outputs audio associated with the floating image in space to the user. A floating image display device.

5. In the spatial floating image display device according to claim 1, The enclosure is equipped with input / output terminals on its side, Power is supplied from an external source to the rechargeable battery housed in the lower part of the housing via the input / output terminals. A floating image display device.

6. In the spatial floating image display device according to claim 1, The enclosure is equipped with input / output terminals on the side of the upper part, A signal is supplied to the video display device from an external source via the input / output terminal. A floating image display device.

7. In the spatial floating image display device according to claim 1, The cylindrical housing can be stored in at least part of a bottle holder inside the vehicle. A floating image display device.

8. In the spatial floating image display device according to claim 1, The outside of the aforementioned window section is provided with a cover. A floating image display device.

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