Aerial floating image display device

Abstract

To provide a more suitable aerial levitation image display device. [Solution] An aerial levitation image display device comprising: an image display unit for displaying an image; a first housing for holding the image display unit; a polarizing mirror; a polarizing mirror holder for holding the polarizing mirror; a retroreflective plate; a second housing for holding the retroreflective plate; a first variable mechanism for varying the relative angle between the first housing and the polarizing mirror holder; and a second variable mechanism for varying the relative angle between the second housing and the polarizing mirror holder. The first housing and the polarizing mirror holder are connected via the first variable mechanism, and the rotation axis of the first variable mechanism is contained within the first housing when the first housing is viewed from the direction of the rotation axis of the first variable mechanism. The second housing and the polarizing mirror holder are connected via a second variable mechanism, and the rotation axis of the second variable mechanism is contained within the second housing when the second housing is viewed from the direction of the rotation axis of the second variable mechanism.

Description

Technical Field

[0001] The present invention relates to an airborne video display device.

Background Art

[0002] Regarding airborne information display technology, for example, it is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the disclosure of Patent Document 1, the configurations for obtaining practical brightness and quality of airborne video, and the configurations for allowing users to view airborne video more enjoyably, etc. were not sufficiently considered.

[0005] An object of the present invention is to provide a more suitable airborne video display device.

Means for Solving the Problems

[0006] To solve the above problems, for example, the configuration described in the claims is adopted. The present application includes multiple means for solving the above problems, but one example is an aerial levitation image display device for displaying aerial levitation images, comprising: an image display unit for displaying images; a first housing for holding the image display unit; a polarizing mirror; a polarizing mirror holder for holding the polarizing mirror; a retroreflective plate; a second housing for holding the retroreflective plate; a first variable mechanism for varying the relative angle between the first housing and the polarizing mirror holder; and a second variable mechanism for varying the relative angle between the second housing and the polarizing mirror holder. The structure comprises a first housing and a polarizing mirror holder, wherein the first housing and the polarizing mirror holder are connected via a first variable mechanism, and the rotation axis of the first variable mechanism is contained within the first housing when the first housing is viewed from the direction of the rotation axis of the first variable mechanism; and the second housing and the polarizing mirror holder are connected via a second variable mechanism, and the rotation axis of the second variable mechanism is contained within the second housing when the second housing is viewed from the direction of the rotation axis of the second variable mechanism. [Effects of the Invention]

[0007] According to the present invention, a more suitable aerial floating image display device can be realized. Other problems, configurations, and effects will be clarified in the following description of embodiments. [Brief explanation of the drawing]

[0008] [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 2A] 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 2B] 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 2C] 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 an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4A] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4B] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4C] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4D] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4E] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4F] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4G] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4H] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4I] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4J] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4K] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4L] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 4M] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 5] This cross-sectional view shows an example of a specific configuration of a light source device according to one embodiment of the present invention. [Figure 6] This cross-sectional view shows a specific example of the configuration of a light source device according to one embodiment of the present invention. [Figure 7]It is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 8] It is a layout diagram showing a main part of a spatial floating image display device according to an embodiment of the present invention. [Figure 9] It is a cross-sectional view showing the configuration of a display device according to an embodiment of the present invention. [Figure 10] It is a cross-sectional view showing the configuration of a display device according to an embodiment of the present invention. [Figure 11] It is an explanatory diagram for explaining the light source diffusion characteristics of a video display device according to an embodiment of the present invention. [Figure 12] It is an explanatory diagram for explaining the diffusion characteristics of a video display device according to an embodiment of the present invention. [Figure 13A] It is an explanatory diagram of an example of a problem solved by image processing according to an embodiment of the present invention. [Figure 13B] It is an explanatory diagram of an example of image processing according to an embodiment of the present invention. [Figure 13C] It is an explanatory diagram of an example of video display processing according to an embodiment of the present invention. [Figure 13D] It is an explanatory diagram of an example of video display processing according to an embodiment of the present invention. [Figure 14A] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14B] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14C] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14D] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14E] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14F] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14G] It is a diagram showing an example of the configuration of a spatial floating image display device according to an embodiment of the present invention. [Figure 14H] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14I] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14J] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14K] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14L] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14M] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14N] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Figure 14O] This figure shows an example of the configuration of a spatially floating image display device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the examples described herein, and various modifications and alterations are possible by those skilled in the art within the scope of the technical ideas disclosed herein. Furthermore, in all the figures used to illustrate the present invention, components having the same function are given the same reference numerals, and repeated descriptions may be omitted.

[0010] The following embodiments relate to an image display device capable of transmitting an image generated by image light from an image light source through a transparent component that partitions a space, such as glass, and displaying it as a floating image in space outside the transparent component. In the following description of embodiments, the image floating in space is referred to as a "floating image in space." Instead of this term, other terms such as "aerial image," "spatial image," "floating image in space," "floating optical image of a displayed image," or "floating optical image of a displayed image in space" may be used. The term "floating image in space," which is mainly used in the description of embodiments, is used as a representative example of these terms.

[0011] According to the following embodiment, a suitable video display device can be realized for applications such as bank ATMs, train station ticket machines, and digital signage. For example, currently, bank ATMs and train station ticket machines typically use touch panels, but by using a transparent glass surface or a light-transmitting plate material, high-resolution video information can be displayed on this glass surface or light-transmitting plate material in a state of floating in space. At this time, by making the divergence angle of the emitted video light small, i.e., acute, and further aligning it to a specific polarization, only the normal reflected light is efficiently reflected by the retroreflector, resulting in high light utilization efficiency. This suppresses ghost images that occur in addition to the main floating image, which was a problem in conventional retroreflection methods, and allows for the acquisition of a clear floating image. Furthermore, the device including the light source of this embodiment can provide a novel and highly usable floating image display device (floating image display system) that can significantly reduce power consumption. In addition, for example, a floating image display device for vehicles can be provided that enables so-called unidirectional floating image display, which is visible inside and / or outside a vehicle.

[0012] <Example 1> <An example of how a spatially floating image display device can be used> Figure 1 is a diagram showing an example of how to use a spatially floating image display device according to one embodiment of the present invention, and is a diagram showing the overall configuration of the spatially floating image display device according to this embodiment. The specific configuration of the spatially floating image display device will be described in detail using Figure 2, etc., but light with narrow-angle directivity and specific polarization is emitted from the image display device 1 as an image light beam, and after reflection in the optical system inside the spatially floating image display device, it enters the retroreflector plate 2, is retroreflected and passes through a transparent member 100 (glass, etc.), and forms an aerial image (spatially floating image 3), which is a real image, on the outside of the glass surface. In the following embodiments, the retroreflector plate 2 (retroreflective plate) will be used as an example of a retroreflective member. However, the retroreflector plate 2 of the present invention is not limited to a planar plate, but is used as an example of a concept that includes a sheet-like retroreflector attached to a planar or non-planar member, or the entire assembly in which a sheet-like retroreflector is attached to a planar or non-planar member.

[0013] Furthermore, in stores and other similar establishments, the space is partitioned by a translucent material such as glass, called a "show window" (also known as "window glass") 105. According to the spatial floating image display device of this embodiment, it is possible to transmit such a transparent material and display the floating image in one direction to the outside and / or inside of the store (space).

[0014] 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 polarizations in the window glass 105, it is also possible to reflect the light and form an aerial image at a desired location inside the store.

[0015] <Example of optical system configuration for a floating image display device> Figure 2A is a diagram showing an example of the configuration of the optical system 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 2A. As shown in Figure 2A(1), a display device 1 is provided that emits image light of a specific polarization at a narrow angle in the oblique direction of a transparent member 100 such as glass. The 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.

[0016] The image light of a specific polarization from the display device 1 is reflected by a polarization separation member 101 (in the figure, the polarization separation member 101 is formed in a sheet shape and adhered to the transparent member 100) which has a film that selectively reflects the image light of the specific polarization, and is incident on the retroreflector 2. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflector 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 retroreflector 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 is transmitted through the polarization separation member 101. The image light that has been transmitted 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.

[0017] Here, we will describe a first example of polarization design in the optical system shown in Figure 2A. For example, the display device 1 may emit S-polarized video light to the polarization separation member 101, and the polarization separation member 101 may have the characteristic of reflecting S-polarized light and transmitting P-polarized light. In this case, the S-polarized video light that reaches the polarization separation member 101 from the display device 1 is reflected by the polarization separation member 101 and heads towards the retroreflector 2. When the video light is reflected by the retroreflector 2, it passes through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2 twice, so the video light is converted from S-polarized to P-polarized light. The video light converted to P-polarized light heads towards the polarization separation member 101 again. Here, since the polarization separation member 101 has the characteristic of reflecting S-polarized light and transmitting P-polarized light, the P-polarized video light passes through the polarization separation member 101 and then through the transparent member 100. Since the image light transmitted through the transparent member 100 is light generated by the retroreflector 2, a floating image 3, which is an optical image of the display image of the display device 1, is formed at a position that is mirror-like to the display image of the display device 1 with respect to the polarization separation member 101. With such a polarization design, a floating image 3 can be suitably formed.

[0018] Next, a second example of polarization design in the optical system shown in Figure 2A will be described. For example, the display device 1 may emit P-polarized image light to the polarization separation member 101, and the polarization separation member 101 may have the characteristic of reflecting P-polarized light and transmitting S-polarized light. In this case, the P-polarized image light that reaches the polarization separation member 101 from the display device 1 is reflected by the polarization separation member 101 and heads towards the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2 twice, so the image light is converted from P-polarized to S-polarized light. The image light converted to S-polarized light heads towards the polarization separation member 101 again. Here, since the polarization separation member 101 has the characteristic of reflecting P-polarized light and transmitting S-polarized light, the S-polarized image light passes through the polarization separation member 101 and then through the transparent member 100. Since the image light transmitted through the transparent member 100 is light generated by the retroreflector 2, a floating image 3, which is an optical image of the display image of the display device 1, is formed at a position that is mirror-like to the display image of the display device 1 with respect to the polarization separation member 101. With such a polarization design, a floating image 3 can be suitably formed.

[0019] The light that forms the floating image 3 is a collection of light rays converging from the retroreflector 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 of Figure 2A, when a user views from the direction of arrow A, the floating image 3 is visible as a bright image. However, when another person views from the direction of arrow B, the floating image 3 cannot be seen 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 directly facing the user.

[0020] Furthermore, depending on the performance of the retroreflector 2, the polarization axis of the reflected image light may become uneven. The reflection angle may also become uneven. Such uneven light may not maintain the polarization state and propagation angle assumed in the design. For example, light with such an unintended polarization state and propagation angle may re-enter the image display side of the liquid crystal display panel 11 directly from the position of the retroreflector 2 without passing through the polarization separation member. Light with such an unintended polarization state and propagation angle may also be reflected by components within the floating image display device and then re-enter the image display side of the liquid crystal display panel 11. This re-entered light on the image display side of the liquid crystal display panel 11 may be re-reflected by the image display surface of the liquid crystal display panel 11 that constitutes the display device 1, potentially generating ghost images and degrading the image quality of the floating image. Therefore, in this embodiment, an absorbing polarizer 12 may be provided on the image display surface of the display device 1. The image light emitted from the display device 1 is transmitted through the absorbing polarizer 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorbing polarizer 12, thereby suppressing the above-mentioned re-reflection. This prevents image quality degradation due to ghost images of floating images in space. Specifically, if the display device 1 emits S-polarized image light to the polarization separation member 101, the absorbing polarizer 12 should be a polarizer that absorbs P-polarized light. Alternatively, if the display device 1 emits P-polarized image light to the polarization separation member 101, the absorbing polarizer 12 should be a polarizer that absorbs S-polarized light.

[0021] 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.

[0022] Next, Figure 2A(2) shows the surface shape of a retroreflector manufactured by Nippon Carbide Industries, Ltd., which was used in this study as a typical retroreflector 2. Light rays incident inside the 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, and a spatially floating image, which is a real image, is displayed on the display device 1.

[0023] The resolution of this floating image 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 of the retroreflective plate 2 shown in Figure 2A(2). For example, when using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective portion is 240 μm and the pitch is 300 μm, then one pixel of the floating image will be equivalent to 300 μm. As a result, the effective resolution of the floating image is reduced to about one-third.

[0024] Therefore, in order to make the resolution of the floating image in space equivalent to the resolution of the display device 1, it is desirable to make the diameter and pitch of the retroreflective portion close to that of 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 plate and the pixels of the liquid crystal display panel, it is good to design the respective pitch ratios to be different from integer multiples of one pixel. Furthermore, the shape should be arranged so that none of the sides of the retroreflective portion overlap with any of the sides of one pixel of the liquid crystal display panel.

[0025] The surface shape of the retroreflector according to this embodiment is not limited to the example described above. It may have various surface shapes that realize retroreflection. Specifically, retroreflective elements formed by periodically arranging triangular pyramidal prisms, hexagonal pyramidal prisms, other polygonal prisms, or combinations thereof may be provided on the surface of the retroreflector according to this embodiment. Alternatively, retroreflective elements that form cube corners by periodically arranging these prisms may be provided on the surface of the retroreflector according to this embodiment. Alternatively, capsule lens type retroreflective elements formed by periodically arranging glass beads may be provided on the surface of the retroreflector according to this embodiment. Since the detailed configuration of these retroreflective elements can be done using existing technology, a detailed explanation will be omitted. Specifically, the technology disclosed in Japanese Patent Publication No. 2001-33609, Japanese Patent Publication No. 2001-264525, Japanese Patent Publication No. 2005-181555, Japanese Patent Publication No. 2008-70898, Japanese Patent Publication No. 2009-229942, etc., can be used.

[0026] <Another example of the optical system configuration for a spatially floating image display device 1> Another example of the optical system configuration for the floating image display device will be explained using Figure 2B. In Figure 2B, components with the same reference numerals as those in Figure 2A have the same function and configuration as those in Figure 2A. For simplicity, repeated explanations of such components will be omitted.

[0027] In the optical system shown in Figure 2B, as in Figure 2A, image light with a specific polarization is output from the display device 1. The image light with a specific polarization output from the display device 1 is input to the polarization separation member 101B. The polarization separation member 101B is a member that selectively transmits image light with a specific polarization. Unlike the polarization separation member 101 in Figure 2A, the polarization separation member 101B is not integrated with the transparent member 100, but has an independent plate-like shape. Therefore, the polarization separation member 101B may also be described as a polarization separation plate. The polarization separation member 101B may be configured as a reflective polarizer, for example, by attaching a polarization separation sheet to a transparent member. Alternatively, it may be formed by a metal multilayer film that selectively transmits the specific polarization and reflects the polarization of other specific polarizations to the transparent member. In Figure 2B, the polarization separation member 101B is configured to transmit image light with a specific polarization output from the display device 1.

[0028] The image light that has passed through the polarization separation member 101B is incident on the retroreflector 2. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflector. The image light is polarized from one polarization to the other by passing through the λ / 4 plate 21 twice, once when it is incident on the retroreflector and once when it is emitted. Here, the polarization separation member 101B has the property of reflecting the polarization of the other polarization that has been polarized by the λ / 4 plate 21, so the image light after polarization conversion is reflected by the polarization separation member 101B. The image light reflected by the polarization separation member 101B passes through the transparent member 100, forming a spatially floating image 3, which is a real image, on the outside of the transparent member 100.

[0029] Here, we will describe a first example of polarization design in the optical system shown in Figure 2B. For example, the display device 1 may emit P-polarized image light to the polarization separation member 101B, and the polarization separation member 101B may have the characteristic of reflecting S-polarized light and transmitting P-polarized light. In this case, the P-polarized image light that reaches the polarization separation member 101B from the display device 1 passes through the polarization separation member 101B and heads towards the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2 twice, so the image light is converted from P-polarized to S-polarized light. The image light converted to S-polarized light heads towards the polarization separation member 101B again. Here, since the polarization separation member 101B has the characteristic of reflecting S-polarized light and transmitting P-polarized light, the S-polarized image light is reflected by the polarization separation member 101 and transmitted through the transparent member 100. Since the image light transmitted through the transparent member 100 is light generated by the retroreflector 2, a floating image 3, which is an optical image of the display image of the display device 1, is formed at a position that is mirror-like to the display image of the display device 1 with respect to the polarization separation member 101B. With such a polarization design, a floating image 3 can be suitably formed.

[0030] Next, a second example of polarization design in the optical system shown in Figure 2B will be described. For example, the display device 1 may emit S-polarized video light to the polarization separation member 101B, and the polarization separation member 101B may be configured to reflect P-polarized light and transmit S-polarized light. In this case, the S-polarized video light that reaches the polarization separation member 101B from the display device 1 passes through the polarization separation member 101B and heads towards the retroreflector 2. When the video light is reflected by the retroreflector 2, it passes through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2 twice, so the video light is converted from S-polarized to P-polarized light. The video light converted to P-polarized light heads towards the polarization separation member 101B again. Here, since the polarization separation member 101B has the characteristic of reflecting P-polarized light and transmitting S-polarized light, the P-polarized video light is reflected by the polarization separation member 101 and transmitted through the transparent member 100. Since the image light transmitted through the transparent member 100 is light generated by the retroreflector 2, a floating image 3, which is an optical image of the display image of the display device 1, is formed at a position that is mirror-like to the display image of the display device 1 with respect to the polarization separation member 101B. With such a polarization design, the floating image 3 can be suitably formed.

[0031] In Figure 2B, the image display surface of the display device 1 and the surface of the retroreflector 2 are arranged parallel to each other. The polarization separation member 101B is positioned at an angle α (e.g., 30°) relative to the image display surface of the display device 1 and the surface of the retroreflector 2. As a result, in the reflection by the polarization separation member 101B, the direction of propagation of the image light reflected by the polarization separation member 101B (the direction of the principal ray of the image light) differs from the direction of propagation of the image light incident from the retroreflector 2 (the direction of the principal ray of the image light) by an angle β (e.g., 60°). With this configuration, in the optical system of Figure 2B, image light is output at a predetermined angle shown toward the outside of the transparent member 100, forming a real image of a floating image in space 3. In the configuration of Figure 2B, when a user views from the direction of arrow A, the floating image in space 3 is visible as a bright image. However, when another person views from the direction of arrow B, the floating image in space 3 cannot be seen as an image at all. This characteristic makes it ideal for systems that display video requiring high security, or highly confidential video that should be kept hidden from the user.

[0032] As explained above, the optical system in Figure 2B, although having a different configuration from the optical system in Figure 2A, can form suitable floating images in space, just like the optical system in Figure 2A.

[0033] Alternatively, an absorbing polarizer may be provided on the side of the transparent member 100 facing the polarization separation member 101B. This absorbing polarizer should transmit the polarization of the image light from the polarization separation member 101B and absorb the polarization that is 90° out of phase with the polarization of the image light from the polarization separation member 101B. In this way, the image light for forming the floating image 3 can be sufficiently transmitted, while the ambient light incident on the floating image 3 side of the transparent member 100 can be reduced by approximately 50%. This reduces stray light in the optical system shown in Figure 2B, which is caused by ambient light incident on the floating image 3 side of the transparent member 100.

[0034] <Another example of the optical system configuration for a floating image display device (2)> Another example of the optical system configuration for the floating image display device will be explained using Figure 2C. In Figure 2C, components with the same reference numerals as those in Figure 2B have the same function and configuration as those in Figure 2B. Such configurations will not be repeated in order to simplify the explanation.

[0035] The only difference between the optical system in Figure 2C and the optical system in Figure 2B is the positioning angle of the polarization separation member 101B with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. All other configurations are the same as those of the optical system in Figure 2B, so repeated explanations are omitted. The polarization design of the optical system in Figure 2C is also the same as that of the optical system in Figure 2B, so repeated explanations are omitted.

[0036] In the optical system shown in Figure 2C, the polarization separation member 101B is positioned at an angle α with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. In Figure 2C, this angle α is 45°. With this configuration, in the reflection by the polarization separation member 101B, the angle β between the direction of propagation of the image light reflected by the polarization separation member 101B (the direction of the principal ray of the image light) and the direction of propagation of the image light incident from the retroreflector 2 (the direction of the principal ray of the image light) is 90°. With this configuration, the image display surface of the display device 1 and the surface of the retroreflector 2 are perpendicular to the direction of propagation of the image light reflected by the polarization separation member 101B, thus simplifying the angular relationships of the surfaces constituting the optical system. If the surface of the transparent member 100 is positioned perpendicular to the direction of propagation of the image light reflected by the polarization separation member 101B, the angular relationships of the surfaces constituting the optical system can be further simplified. In the configuration shown in Figure 2C, when a user views the image from the direction of arrow A, the floating image 3 is visible as a bright image. However, when another person views the image from the direction of arrow B, the floating image 3 is not visible at all. This characteristic makes it ideal for systems that display highly secure images or highly confidential images that should be concealed from people directly facing the user.

[0037] As explained above, the optical system in Figure 2C, while having a different configuration from the optical systems in Figures 2A and 2B, can form suitable floating images in space, just like the optical systems in Figures 2A and 2B. Furthermore, the angles of the surfaces constituting the optical system can be made simpler.

[0038] Alternatively, an absorbing polarizer may be provided on the side of the transparent member 100 facing the polarization separation member 101B. This absorbing polarizer should transmit the polarization of the image light from the polarization separation member 101B and absorb the polarization that is 90° out of phase with the polarization of the image light from the polarization separation member 101B. In this way, the image light for forming the floating image 3 can be sufficiently transmitted, while the ambient light incident on the floating image 3 side of the transparent member 100 can be reduced by approximately 50%. This reduces stray light in the optical system shown in Figure 2C, which is caused by ambient light incident on the floating image 3 side of the transparent member 100.

[0039] As described above, the optical systems shown in Figures 2A, 2B, and 2C can provide brighter, higher-quality floating images.

[0040] <<Block diagram of the internal structure of the floating image display device>> Next, a block diagram of the internal configuration of the floating image display device 1000 will be described. Figure 3 is a block diagram showing an example of the internal configuration of the floating image display device 1000.

[0041] The floating video display device 1000 includes a retroreflective section 1101, a video display section 1102, a light guide 1104, a light source 1105, a power supply 1106, an external power input interface 1111, an operation input section 1107, a non-volatile memory 1108, a memory 1109, a control section 1110, a video signal input section 1131, an audio signal input section 1133, a communication section 1132, an aerial operation detection sensor 1351, an aerial operation detection section 1350, an audio output section 1140, a video control section 1160, a storage section 1170, an imaging section 1180, and the like. It may also include a removable media interface 1134, an attitude sensor 1113, a transmissive self-emissive video display device 1650, a second display device 1680, or a secondary battery 1112.

[0042] Each component of the floating video display device 1000 is arranged in the housing 1190. Note that the imaging unit 1180 and the aerial operation detection sensor 1351 shown in Figure 3 may be provided on the outside of the housing 1190.

[0043] The retroreflective section 1101 in Figure 3 corresponds to the retroreflective plate 2 in Figures 2A, 2B, and 2C. The retroreflective section 1101 retroreflectively reflects light modulated by the image display section 1102. The floating image 3 is formed by the light from the reflected light from the retroreflective section 1101 that is output to the outside of the floating image display device 1000.

[0044] The image display unit 1102 in Figure 3 corresponds to the liquid crystal display panel 11 in Figures 2A, 2B, and 2C. The light source 1105 in Figure 3 corresponds to the light source device 13 in Figures 2A, 2B, and 2C. The image display unit 1102, light guide 1104, and light source 1105 in Figure 3 correspond to the display device 1 in Figures 2A, 2B, and 2C.

[0045] The video display unit 1102 is a display unit that generates an image by modulating transmitted light based on a video signal input under control by the video control unit 1160, which will be described later. The video display unit 1102 corresponds to the liquid crystal display panel 11 in Figures 2A, 2B, and 2C. For example, a transmissive liquid crystal panel can be used as the video display unit 1102. Alternatively, a reflective liquid crystal panel or a DMD (Digital Micromirror Device: registered trademark) panel that modulates reflected light may also be used as the video display unit 1102.

[0046] The light source 1105 generates light for the image display unit 1102 and is a solid-state light source such as an LED or laser light source. The power supply 1106 converts the AC current input from an external source via the external power input interface 1111 into DC current and supplies power to the light source 1105. The power supply 1106 also supplies the necessary DC current to each part of the floating image display device 1000. The secondary battery 1112 stores the power supplied from the power supply 1106. The secondary battery 1112 also supplies power to the light source 1105 and other components that require power via the external power input interface 1111 when power is not supplied from an external source. In other words, if the floating image display device 1000 is equipped with a secondary battery 1112, the user can use the floating image display device 1000 even when power is not supplied from an external source.

[0047] The light guide 1104 guides the light generated by the light source 1105 and illuminates the image display unit 1102. The combination of the light guide 1104 and the light source 1105 can also be called the backlight of the image display unit 1102. The light guide 1104 may be mainly made of glass. The light guide 1104 may be mainly made of plastic. The light guide 1104 may be made of mirrors. Various combinations of the light guide 1104 and the light source 1105 are possible. Specific examples of combinations of the light guide 1104 and the light source 1105 will be explained in detail later.

[0048] The aerial operation detection sensor 1351 is a sensor that detects the operation of the floating video 3 by the user 230's finger. The aerial operation detection sensor 1351 senses, for example, the area that overlaps with the entire display range of the floating video 3. Alternatively, the aerial operation detection sensor 1351 may sense only the area that overlaps with at least a portion of the display range of the floating video 3.

[0049] Specific examples of the aerial operation detection sensor 1351 include distance sensors using invisible light such as infrared, invisible light lasers, and ultrasonic waves. The aerial operation detection sensor 1351 may also be configured by combining multiple sensors to detect coordinates on a two-dimensional plane. Furthermore, the aerial operation detection sensor 1351 may consist of a Time of Flight (ToF) LiDAR (Light Detection and Ranging) or an image sensor.

[0050] The aerial operation detection sensor 1351 only needs to be able to sense touch operations, etc., on an object displayed as a floating image 3 in space, using the user's finger. Such sensing can be performed using existing technologies.

[0051] The aerial operation detection unit 1350 acquires sensing signals from the aerial operation detection sensor 1351 and, based on the sensing signals, calculates whether or not the user 230's finger has made contact with an object in the floating spatial image 3, and the position where the user 230's finger made contact with the object (contact position). The aerial operation detection unit 1350 is composed of circuits such as an FPGA (Field Programmable Gate Array). In addition, some functions of the aerial operation detection unit 1350 may be implemented in software, for example, by a spatial operation detection program executed in the control unit 1110.

[0052] The aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be built into the floating video display device 1000, or they may be provided separately from the floating video display device 1000. When provided separately from the floating video display device 1000, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 are configured to transmit information and signals to the floating video display device 1000 via wired or wireless communication lines or video signal transmission lines.

[0053] Furthermore, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be provided as separate components. This makes it possible to construct a system in which the floating video display device 1000 without the aerial operation detection function is used as the main unit, and only the aerial operation detection function can be added as an option. Alternatively, the aerial operation detection sensor 1351 may be a separate component, and the aerial operation detection unit 1350 may be built into the floating video display device 1000. When it is desired to place the aerial operation detection sensor 1351 more freely relative to the installation position of the floating video display device 1000, there is an advantage to having only the aerial operation detection sensor 1351 as a separate component.

[0054] The imaging unit 1180 is a camera with an image sensor that captures images of the space near the floating image 3 and / or the user's face, arms, fingers, etc. Multiple imaging units 1180 may be provided. By using multiple imaging units 1180, or by using imaging units with depth sensors, the aerial operation detection unit 1350 can be assisted when detecting touch operations on the floating image 3 by the user 230. The imaging unit 1180 may be provided separately from the floating image display device 1000. If the imaging unit 1180 is provided separately from the floating image display device 1000, it should be configured to transmit imaging signals to the floating image display device 1000 via a wired or wireless communication connection path.

[0055] For example, if the aerial operation detection sensor 1351 is configured as an object intrusion sensor that detects whether or not an object has entered a plane (intrusion detection plane) that includes the display surface of the floating spatial image 3, the aerial operation detection sensor 1351 may not be able to detect information such as how far away an object that has not entered the intrusion detection plane (for example, a user's finger) is from the intrusion detection plane, or how close an object is to the intrusion detection plane.

[0056] In such cases, the distance between the object and the intrusion detection plane can be calculated by using information such as depth calculation information of the object based on images captured by multiple imaging units 1180 and depth information of the object from a depth sensor. This information, as well as various other information such as the distance between the object and the intrusion detection plane, is then used for various display controls of the floating spatial image 3.

[0057] Alternatively, instead of using the aerial operation detection sensor 1351, the aerial operation detection unit 1350 may detect touch operations on the floating video 3 by the user 230 based on the image captured by the imaging unit 1180.

[0058] Alternatively, the imaging unit 1180 may capture an image of the face of the user 230 operating the floating video 3, and the control unit 1110 may perform user identification processing. Furthermore, in order to determine whether other people are standing around or behind the user 230 operating the floating video 3 and whether they are peeking at the user 230's operation of the floating video 3, the imaging unit 1180 may capture an area that includes the user 230 operating the floating video 3 and the area surrounding the user 230.

[0059] The operation input unit 1107 is, for example, an operation button, a signal receiving unit such as a remote controller, or an infrared light receiving unit, and inputs signals for operations other than aerial operations (touch operations) by the user 230. Separately from the aforementioned user 230 who touches the floating spatial image 3, the operation input unit 1107 may also be used, for example, by an administrator to operate the floating spatial image display device 1000.

[0060] The video signal input unit 1131 receives video data by connecting an external video output device. Various digital video input interfaces are possible for the video signal input unit 1131. For example, it can be configured with an HDMI (High-Definition Multimedia Interface) standard video input interface, a DVI (Digital Visual Interface) standard video input interface, or a DisplayPort standard video input interface. Alternatively, an analog video input interface such as analog RGB or composite video may be provided. The audio signal input unit 1133 receives audio data by connecting an external audio output device. The audio signal input unit 1133 can be configured with an HDMI standard audio input interface, an optical digital terminal interface, or a coaxial digital terminal interface. In the case of an HDMI standard interface, the video signal input unit 1131 and the audio signal input unit 1133 may be configured as an integrated interface with terminals and cables. The audio output unit 1140 can output audio based on the audio data input to the audio signal input unit 1133. The audio output unit 1140 may be configured as a speaker. Furthermore, the audio output unit 1140 may output built-in operation sounds or error warning sounds. Alternatively, the audio output unit 1140 may be configured to output as a digital signal to an external device, such as the Audio Return Channel function specified in the HDMI standard.

[0061] The non-volatile memory 1108 stores various data used by the floating image display device 1000. The data stored in the non-volatile memory 1108 includes, for example, data for various operations displayed on the floating image 3, display icons, data and layout information for objects that the user operates. Memory 1109 stores video data to be displayed as the floating image 3, control data for the device, and the like.

[0062] The control unit 1110 controls the operation of each connected part. The control unit 1110 may also work in cooperation with a program stored in the memory 1109 to perform calculation processing based on information acquired from each part of the floating image display device 1000.

[0063] The communication unit 1132 communicates with external devices, external servers, etc., via a wired or wireless communication interface. If the communication unit 1132 has a wired communication interface, the wired communication interface may be configured as, for example, an Ethernet standard LAN interface. If the communication unit 1132 has a wireless communication interface, it may be configured as, for example, a Wi-Fi communication interface, a Bluetooth communication interface, or a mobile communication interface such as 4G or 5G. Various types of data, such as video data, image data, and audio data, are transmitted and received through communication via the communication unit 1132.

[0064] Furthermore, the removable media interface 1134 is an interface for connecting removable recording media. Removable recording media may consist of semiconductor memory such as solid-state drives (SSDs), magnetic recording media recording devices such as hard disk drives (HDDs), or optical recording media such as optical discs. The removable media interface 1134 can read various types of information, such as video data, image data, and audio data, recorded on the removable recording media. Video data, image data, etc., recorded on the removable recording media are output as floating-in-space images 3 via the video display unit 1102 and the retroreflective unit 1101.

[0065] The storage unit 1170 is a storage device that records various types of information, such as video data, image data, and audio data. The storage unit 1170 may be composed of a magnetic recording medium such as a hard disk drive (HDD) or a semiconductor memory such as a solid-state drive (SSD). The storage unit 1170 may have various types of information, such as video data, image data, and audio data, pre-recorded in it at the time of product shipment. The storage unit 1170 may also record various types of information, such as video data, image data, and audio data, acquired from external devices or external servers via the communication unit 1132.

[0066] The video data, image data, etc., recorded in the storage unit 1170 are output as floating-in-space video 3 via the video display unit 1102 and the retroreflection unit 1101. The video data, image data, etc., of display icons and user-operated objects, etc., which are displayed as floating-in-space video 3, are also recorded in the storage unit 1170.

[0067] Layout information such as display icons and objects shown as the floating spatial image 3, as well as various metadata information related to the objects, are also recorded in the storage unit 1170. Audio data recorded in the storage unit 1170 is output as audio from, for example, the audio output unit 1140.

[0068] The video control unit 1160 performs various controls related to the video signals input to the video display unit 1102. The video control unit 1160 may also be called a video processing circuit and may be composed of hardware such as an ASIC, FPGA, or video processor. The video control unit 1160 may also be called a video processing unit or image processing unit. For example, the video control unit 1160 performs video switching control, such as determining which video signal to input to the video display unit 1102 from among the video signals stored in the memory 1109 and the video signals (video data) input to the video signal input unit 1131.

[0069] Alternatively, the video control unit 1160 may generate a superimposed video signal by superimposing the video signal to be stored in the memory 1109 and the video signal input from the video signal input unit 1131, and then input the superimposed video signal to the video display unit 1102 to form the composite image as a floating image 3.

[0070] Furthermore, the video control unit 1160 may perform image processing on video signals input from the video signal input unit 1131 and video signals stored in the memory 1109. Examples of image processing include scaling, which enlarges, reduces, and transforms images; brightness adjustment, which changes the brightness; contrast adjustment, which changes the contrast curve of an image; and retinex processing, which decomposes an image into its light components and changes the weighting of each component.

[0071] Furthermore, the video control unit 1160 may perform special effects video processing on the video signal input to the video display unit 1102 to assist the user 230's aerial operation (touch operation). Special effects video processing is performed, for example, based on the detection result of the user 230's touch operation by the aerial operation detection unit 1350 or on the image captured by the imaging unit 1180 of the user 230.

[0072] The attitude sensor 1113 is a sensor composed of a gravity sensor, an acceleration sensor, or a combination thereof, and can detect the orientation in which the floating video display device 1000 is installed. Based on the attitude detection result of the attitude sensor 1113, the control unit 1110 may control the operation of each connected part. For example, if an undesirable orientation for the user is detected, the control unit 1110 may stop displaying the video that the video display unit 1102 was showing and display an error message to the user. Alternatively, if the attitude sensor 1113 detects that the installation orientation of the floating video display device 1000 has changed, the control unit 1110 may rotate the orientation of the video that the video display unit 1102 was showing.

[0073] As explained above, the floating image display device 1000 is equipped with various functions. However, the floating image display device 1000 does not need to have all of these functions; any configuration is acceptable as long as it has the function of forming the floating image 3.

[0074] <Example configuration of a floating image display device> Next, we will describe an example configuration of the floating image display device. The layout of the components of the floating image display device according to this embodiment can vary depending on the usage. Below, we will describe each of the layouts shown in Figures 4A to 4M. In all of the examples in Figures 4A to 4M, the thick lines surrounding the floating image display device 1000 indicate an example of the housing structure of the floating image display device 1000.

[0075] Figure 4A shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4A is equipped with an optical system corresponding to the optical system in Figure 2A. In the floating image display device 1000 shown in Figure 4A, it is installed horizontally so that the side on which the floating image 3 is formed faces upward. That is, in Figure 4A, the floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The floating image 3 is formed above the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels diagonally upward. If the air operation detection sensor 1351 is installed as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger. Note that the x direction is the left-right direction from the user's perspective, the y direction is the front-back direction (depth direction) from the user's perspective, and the z direction is the up-down direction (vertical direction). In the following Figure 4, the definitions of the x, y, and z directions are the same, so repeated explanations will be omitted.

[0076] Figure 4B shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4B is equipped with an optical system corresponding to the optical system in Figure 2A. The floating image display device 1000 shown in Figure 4B is installed vertically so that the side on which the floating image 3 is formed faces the front of the floating image display device 1000 (towards the user 230). That is, in Figure 4B, the floating image display device has a transparent member 100 installed on the front of the device (towards the user 230). The floating image 3 is formed on the user 230 side relative to the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels diagonally upward. If the aerial operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger. As shown in Figure 4B, the airborne operation detection sensor 1351 senses the user's finger from above, allowing it to utilize the reflection of sensing light from the user's fingernail for touch detection. Generally, fingernails have a higher reflectivity than the pads of the fingers, so this configuration can improve the accuracy of touch detection.

[0077] Figure 4C shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4C is equipped with an optical system corresponding to the optical system in Figure 2B. In the floating image display device 1000 shown in Figure 4C, it is installed horizontally so that the side on which the floating image 3 is formed faces upward. That is, in Figure 4C, the floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The floating image 3 is formed above the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels diagonally upward. If the aerial operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger.

[0078] Figure 4D shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4D is equipped with an optical system corresponding to the optical system in Figure 2B. The floating image display device 1000 shown in Figure 4D is installed vertically so that the side on which the floating image 3 is formed faces the front of the floating image display device 1000 (towards the user 230). That is, in Figure 4D, the floating image display device 1000 has a transparent member 100 installed on the front of the device (towards the user 230). The floating image 3 is formed on the user 230 side of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels diagonally upward. If the aerial operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger. Here, as shown in Figure 4D, the airborne operation detection sensor 1351 senses the user's finger from above, and the reflection of the sensing light from the user's fingernail can be used for touch detection. Generally, fingernails have a higher reflectivity than the pads of the fingers, so this configuration can improve the accuracy of touch detection.

[0079] Figure 4E shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4E is equipped with an optical system corresponding to the optical system in Figure 2C. In the floating image display device 1000 shown in Figure 4E, it is installed horizontally so that the side on which the floating image 3 is formed faces upward. That is, in Figure 4E, the floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The floating image 3 is formed above the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels in a direction directly upward. If the air operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger.

[0080] Figure 4F shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4F is equipped with an optical system corresponding to the optical system in Figure 2C. The floating image display device 1000 shown in Figure 4F is installed vertically so that the side on which the floating image 3 is formed faces the front of the floating image display device 1000 (towards the user 230). That is, in Figure 4F, the floating image display device 1000 has a transparent member 100 installed on the front of the device (towards the user 230). The floating image 3 is formed on the user 230 side relative to the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels in the direction toward the user. If the aerial operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger.

[0081] Figure 4G shows an example of the configuration of a floating image display device. The floating image display device 1000 shown in Figure 4G is equipped with an optical system corresponding to the optical system in Figure 2C. In the optical systems of the floating image display devices shown in Figures 4A to 4F, the optical path of the center of the image light emitted from the display device 1 was on the yz plane. That is, within the optical systems of the floating image display devices shown in Figures 4A to 4F, the image light traveled in the front-to-back and up-and-down directions as viewed from the user. In contrast, in the optical system of the floating image display device shown in Figure 4G, the optical path of the center of the image light emitted from the display device 1 is on the xy plane. That is, within the optical system of the floating image display device shown in Figure 4G, the image light travels in the left-to-right and front-to-back directions as viewed from the user. In the floating image display device 1000 shown in Figure 4G, the side on which the floating image 3 is formed is installed so that it faces the front of the device (towards the user 230). In other words, in Figure 4G, the floating image display device 1000 has a transparent member 100 installed on the front of the device (towards the user 230). The floating image 3 is formed on the user side relative to the surface of the transparent member 100 of the floating image display device 1000. The light of the floating image 3 travels toward the user. If the aerial operation detection sensor 1351 is provided as shown in the figure, it is possible to detect operation of the floating image 3 by the user 230's finger.

[0082] Figure 4H shows an example of the configuration of a floating image display device. The floating image display device 1000 in Figure 4H differs from the floating image display device in Figure 4G in that it has a window with a transparent plate 100B made of glass or plastic on the back of the device (opposite the position from which the user 230 views the floating image 3, i.e., opposite the direction of propagation of the image light of the floating image 3 toward the user 230). The other configurations are the same as those of the floating image display device in Figure 4G, so repeated explanations will be omitted. The floating image display device 1000 in Figure 4H has a window with a transparent plate 100B at a position opposite to the direction of propagation of the image light of the floating image 3. Therefore, when the user 230 views the floating image 3, they can recognize the scenery behind the floating image display device 1000 as the background of the floating image 3. Therefore, the user 230 can perceive the floating image 3 as floating in the air in front of the scenery behind the floating image display device 1000. This further enhances the sense of floating in the air of the floating image 3.

[0083] Furthermore, depending on the polarization distribution of the video light output from the display device 1 and the performance of the polarization separation member 101B, a portion of the video light output from the display device 1 may be reflected by the polarization separation member 101B and directed toward the transparent plate 100B. Depending on the coating performance of the surface of the transparent plate 100B, this light may be reflected again by the surface of the transparent plate 100B and may be visible to the user as stray light. Therefore, in order to prevent such stray light, the transparent plate 100B may not be provided in the window on the back of the floating video display device 1000.

[0084] Figure 4I shows an example of the configuration of a floating image display device. The floating image display device 1000 in Figure 4I differs from the floating image display device in Figure 4H in that it has an opening / closing door 1410 for light shielding on the window of the transparent plate 100B located on the back of the device (opposite the position from which the user 230 views the floating image 3). The other configurations are the same as those of the floating image display device in Figure 4H, so repeated explanations are omitted. The opening / closing door 1410 of the floating image display device 1000 in Figure 4I has, for example, a light shielding plate and is equipped with a mechanism for moving (sliding), rotating, or attaching / detaching the light shielding plate, so that the window (rear side window) of the transparent plate 100B located on the back side of the floating image display device 1000 can be switched between an open state and a light-shielded state. The movement (sliding) or rotation of the light shielding plate by the opening / closing door 1410 may be electrically driven by a motor (not shown). This motor may be controlled by the control unit 1110 in Figure 3. Note that in the example shown in Figure 4I, the number of light-shielding plates for the opening / closing door 1410 is two. However, the number of light-shielding plates for the opening / closing door 1410 may be one.

[0085] For example, if the view beyond the window of the transparent panel 100B of the floating image display device 1000 is outdoors, the brightness of sunlight will vary depending on the weather. If the sunlight outdoors is strong, the background of the floating image 3 may become too bright, reducing the visibility of the floating image 3 for the user 230. In such cases, by moving (sliding), rotating, or attaching the light-shielding plate of the opening / closing door 1410 to block the light on the rear window, the background of the floating image 3 will become darker, thereby relatively improving the visibility of the floating image 3. This shielding operation by the light-shielding plate of the opening / closing door 1410 may be performed directly by the force of the user 230's hand. Alternatively, the control unit 1110 may control a motor (not shown) in response to an operation input via the operation input unit 1107 in Figure 3 to perform the shielding operation by the light-shielding plate of the opening / closing door 1410.

[0086] Furthermore, an illuminance sensor may be installed on the rear side of the floating spatial image display device 1000 (opposite side of the user 230), such as near the rear window, to measure the brightness of the space beyond the rear window. In this case, the control unit 1110 in Figure 3 may control a motor (not shown) to open and close the light-shielding plate of the opening / closing door 1410 according to the detection result of the illuminance sensor. By controlling the opening and closing operation of the light-shielding plate of the opening / closing door 1410 in this way, the visibility of the floating spatial image 3 can be more favorably maintained without the user 230 having to manually open or close the light-shielding plate of the opening / closing door 1410.

[0087] Furthermore, the light-shielding plate provided by the opening / closing door 1410 may be manually detachable. Depending on the intended use and installation environment of the spatial floating image display device 1000, the user can choose whether to leave the rear window open or detached. If the rear window is to be used in a detached state for a long period of time, the detachable light-shielding plate can be fixed in the detached state. If the rear window is to be used in an open state for a long period of time, the detachable light-shielding plate can be removed. The light-shielding plate may be attached and detached using screws, a hook structure, or a snap-in structure.

[0088] In the example of the floating video display device 1000 shown in Figure 4I, depending on the polarization distribution of the video light output from the display device 1 and the performance of the polarization separation member 101B, some of the video light output from the display device 1 may be reflected by the polarization separation member 101B and directed toward the transparent plate 100B. Depending on the coating performance of the surface of the transparent plate 100B, this light may be reflected again by the surface of the transparent plate 100B and seen by the user as stray light. Therefore, in order to prevent such stray light, the floating video display device 1000 may be configured without a transparent plate 100B in the window on the back of the device. The window without the transparent plate 100B can be provided with the above-mentioned opening and closing door 1410. In order to prevent such stray light, it is desirable that the inner surface of the housing of the light-shielding plate of the above-mentioned opening and closing door 1410 has a coating or material with low light reflectivity.

[0089] Figure 4J shows an example of the configuration of a floating image display device. The floating image display device 1000 in Figure 4J differs from the floating image display device in Figure 4H in that instead of placing a transparent plate 100B made of glass or plastic in the rear window, an electronically controlled variable transmittance device 1620 is placed therein. The other configurations are the same as those of the floating image display device in Figure 4H, so repeated explanations are omitted. An example of the electronically controlled variable transmittance device 1620 is a liquid crystal shutter. That is, a liquid crystal shutter can control the transmitted light by voltage control of a liquid crystal element sandwiched between two polarizing plates. Therefore, by controlling the liquid crystal shutter to increase the transmittance, the background of the floating image 3 becomes a state where the scenery through the rear window is visible. Alternatively, by controlling the liquid crystal shutter to increase the transmittance, the scenery through the rear window can be made invisible as the background of the floating image 3. Furthermore, since the liquid crystal shutter can be controlled in intermediate lengths, it is possible to set the transmittance to 50% or other states. For example, the control unit 1110 can control the transmittance of the electronically controlled variable transmittance device 1620 in response to an operation input via the operation input unit 1107 in Figure 3. With this configuration, if the view through the rear window is desired as the background for the floating image 3, but the view through the rear window is too bright, reducing the visibility of the floating image 3, the visibility of the floating image 3 can be adjusted by adjusting the transmittance of the electronically controlled variable transmittance device 1620.

[0090] Alternatively, an illuminance sensor may be installed on the rear side of the floating image display device 1000 (opposite the user 230), such as near the rear window, to measure the brightness of the space beyond the rear window. In this case, the control unit 1110 in Figure 3 can control the transmittance of the electronically controlled variable transmittance device 1620 according to the detection result of the illuminance sensor. In this way, the transmittance of the electronically controlled variable transmittance device 1620 can be adjusted according to the brightness of the space beyond the rear window without the user 230 having to perform an operation input via the operation input unit 1107 in Figure 3, thereby making it possible to maintain the visibility of the floating image 3 more favorably.

[0091] Furthermore, in the above example, a liquid crystal shutter was described as an example of the electronically controlled variable transmittance device 1620. In contrast, electronic paper may be used as another example of the electronically controlled variable transmittance device 1620. The same effects as described above can be obtained even when electronic paper is used. Moreover, electronic paper consumes very little power to maintain the halftone state. Therefore, a spatial levitation image display device with lower power consumption can be realized compared to the case in which a liquid crystal shutter is used.

[0092] Figure 4K shows an example of the configuration of a floating image display device. The floating image display device 1000 in Figure 4K differs from the floating image display device in Figure 4G in that it has a transmissive self-emissive image display device 1650 instead of a transparent member 100. The other configurations are the same as those of the floating image display device in Figure 4G, so repeated explanations are omitted.

[0093] In the spatial levitation image display device 1000 shown in Figure 4K, the spatial levitation image 3 is formed outside the spatial levitation image display device 1000 after the image light beam passes through the display surface of the transmissive self-emissive image display device 1650. That is, when an image is displayed on the transmissive self-emissive image display device 1650, which is a two-dimensional planar display, the spatial levitation image 3 can be displayed as a projecting image further in front of the user than the image on the transmissive self-emissive image display device 1650. At this time, the user 230 can simultaneously view two images at different depth positions. The transmissive self-emissive image display device 1650 can be constructed using existing technologies such as transmissive organic EL panels, as disclosed in, for example, Japanese Patent Application Publication No. 2014-216761. Although the transmissive self-emissive image display device 1650 is not shown in Figure 3, it can be configured as a component of the spatial levitation image display device 1000 shown in Figure 3, and connected to other processing units such as the control unit 1110.

[0094] Here, if the transparent self-emissive video display device 1650 displays both the background and objects such as characters, and then performs an effect such as having only the objects such as characters move to the floating video 3 in the foreground space, the user 230 can be provided with a more effective surprise video experience.

[0095] Furthermore, if the interior of the floating image display device 1000 is kept dark, the background of the transmissive self-emissive image display device 1650 becomes sufficiently dark. Therefore, when no image is displayed on the display device 1, or when the light source of the display device 1 is turned off and only the transmissive self-emissive image display device 1650 displays an image, the user 230 will perceive the transmissive self-emissive image display device 1650 as a normal two-dimensional planar display rather than a transmissive display (because the floating image 3 in the embodiment of the present invention is displayed as a real optical image in space without a screen, if the light source of the display device 1 is turned off, the planned display location for the floating image 3 becomes empty space). Therefore, when the transmissive self-emissive image display device 1650 is being used as if it were a general two-dimensional planar display to show an image, characters or objects can be suddenly displayed in mid-air as floating images 3, providing the user 230 with a more effective surprise visual experience.

[0096] Furthermore, the darker the interior of the floating image display device 1000 is made, the more the transmissive self-emissive image display device 1650 appears like a two-dimensional planar display. Therefore, an absorbing polarizing plate (not shown) that transmits the polarization of the image light reflected by the polarization separation member 101B and absorbs polarization that is 90° out of phase with that polarization may be provided on the interior side of the transmissive self-emissive image display device 1650 (the incident surface for the image light reflected by the polarization separation member 101B into the transmissive self-emissive image display device 1650, i.e., the side of the transmissive self-emissive image display device 1650 opposite to the floating image 3). In this way, the impact on the image light forming the floating image 3 is not so great, but the amount of light incident on the interior of the floating image display device 1000 from the outside via the transmissive self-emissive image display device 1650 can be significantly reduced, making the interior of the floating image display device 1000 darker, which is preferable.

[0097] Figure 4L shows an example of the configuration of a floating image display device. The floating image display device 1000 in Figure 4L is a modified version of the floating image display device in Figure 4K. The orientation of the components in the floating image display device 1000 differs from that of the floating image display device in Figure 4K, and is closer to that of the floating image display device in Figure 4F. The functions and operations of each component are the same as those of the floating image display device in Figure 4K, so repeated explanations are omitted.

[0098] In the floating image display device shown in Figure 4L, after the light beam of the image passes through the transmissive self-emissive image display device 1650, the floating image 3 is formed on the user 230 side of the transmissive self-emissive image display device 1650.

[0099] In both the example of the floating image display device in Figure 4K and the example of the floating image display device in Figure 4L, the floating image 3 is displayed superimposed in front of the image on the transmissive self-emissive image display device 1650 to the user 230. Here, the position of the floating image 3 and the position of the image on the transmissive self-emissive image display device 1650 are configured to have a difference in the depth direction. Therefore, when the user moves their head (viewpoint position), they can perceive the depth of the two images due to parallax. Thus, by displaying two images with different depth positions, a three-dimensional image experience can be more favorably provided to the user with the naked eye, without the need for stereoscopic glasses or other such devices.

[0100] Figure 4M shows an example of the configuration of a floating image display device. In the floating image display device 1000 of Figure 4M, a second display device 1680 is provided on the side furthest from the user's perspective relative to the polarization separation member 101B of the floating image display device in Figure 4G. The other configurations are the same as those of the floating image display device in Figure 4G, so repeated explanations are omitted.

[0101] In the configuration example shown in Figure 4M, the second display device 1680 is located behind the display position of the floating image 3, with its display surface facing the floating image 3. With this configuration, the user 230 can view the image from the second display device 1680 and the floating image 3, which are displayed at two different depths, superimposed on each other. In other words, the second display device 1680 is positioned to display the image in the direction of the user 230 who is viewing the floating image 3. Although the second display device 1680 is not shown in Figure 3, it can be configured as a component of the floating image display device 1000 in Figure 3, connected to other processing units such as the control unit 1110.

[0102] In Figure 4M, the video light from the second display device 1680 of the floating video display device 1000 is seen by the user 230 after passing through the polarization separation member 101B. Therefore, in order for the video light from the second display device 1680 to pass through the polarization separation member 101B more favorably, it is desirable that the video light output from the second display device 1680 has polarization in the direction of vibration that the polarization separation member 101B passes through more favorably. That is, it is desirable that the polarization is in the same direction of vibration as the video light output from the display device 1. For example, if the video light output from the display device 1 is S-polarized, it is desirable that the video light output from the second display device 1680 is also S-polarized. Also, if the video light output from the display device 1 is P-polarized, it is desirable that the video light output from the second display device 1680 is also P-polarized.

[0103] The example of the floating image display device in Figure 4M has the same effect as the examples of the floating image display devices in Figure 4K and Figure 4L, in that it displays a second image behind the floating image 3. However, unlike the examples of the floating image display devices in Figure 4K and Figure 4L, in the example of the floating image display device in Figure 4M, the light beam of the image light that forms the floating image 3 does not pass through the second display device 1680. Therefore, the second display device 1680 does not need to be a transmissive self-emissive image display device, and can be a liquid crystal display, which is a two-dimensional planar display. The second display device 1680 can also be an organic EL display. Therefore, in the example of the floating image display device in Figure 4M, it is possible to realize the floating image display device 1000 at a lower cost than in the examples of the floating image display devices in Figure 4K and Figure 4L.

[0104] Here, depending on the polarization distribution of the video light output from the display device 1 and the performance of the polarization separation member 101B, a portion of the video light output from the display device 1 may be reflected by the polarization separation member 101B and directed toward the second display device 1680. This light (a portion of the video light) may be reflected again by the surface of the second display device 1680 and may be visible to the user as stray light.

[0105] Therefore, in order to prevent stray light, an absorbing polarizer may be provided on the surface of the second display device 1680. In this case, the absorbing polarizer should be one that transmits the polarization of the image light output from the second display device 1680 and absorbs polarization that is 90° out of phase with the polarization of the image light output from the second display device 1680. If the second display device 1680 is a liquid crystal display, an absorbing polarizer also exists on the image output side inside the liquid crystal display. However, if there is a cover glass (cover glass on the image display surface side) on the output surface of the absorbing polarizer on the image output side inside the liquid crystal display, it is not possible to prevent stray light caused by reflection from the cover glass due to light from outside the liquid crystal display. Therefore, it is necessary to separately provide the above-mentioned absorbing polarizer on the surface of the cover glass.

[0106] Furthermore, when displaying an image on the second display device 1680, which is a two-dimensional planar display, the floating spatial image 3 can be displayed as an image in front of the user, above the image on the second display device 1680. In this case, the user 230 can simultaneously view two images at different depth positions. By displaying a character on the floating spatial image 3 and a background on the second display device 1680, it is possible to provide the user 230 with the effect of viewing the space in which the character exists in three dimensions.

[0107] Furthermore, if the second display device 1680 displays both the background and objects such as characters, and then has only the objects such as characters move to the floating image 3 in the foreground, the user 230 can be provided with a more effective surprise-style video experience.

[0108] <Display device> Next, the display device 1 of this embodiment will be described with reference to the figures. The display device 1 of this embodiment includes a video display element 11 (liquid crystal display panel) and a light source device 13 that constitutes its light source. Figure 5 shows the light source device 13 together with the liquid crystal display panel as an exploded perspective view.

[0109] As shown by the arrow 30 in Figure 5, this liquid crystal display panel (image display element 11) receives an illumination beam from the light source device 13, which is a backlight device, that has narrow-angle diffusion characteristics, that is, strong directionality (straight-line propagation) and characteristics similar to laser light with the polarization plane aligned in one direction. The liquid crystal display panel (image display element 11) modulates the received illumination beam according to the input video signal. The modulated video light is reflected by the retroreflector 2 and transmitted through the transparent member 100 to form a floating image in space, which is a real image (see Figure 1).

[0110] Furthermore, Figure 5 shows that the display device 1 is configured with 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 a narrow-angle diffuser (not shown) as needed. Specifically, polarizing plates are provided on both sides of the liquid crystal display panel 11, and image light with a specific polarization is emitted after the intensity of the light is modulated by the image signal (see arrow 30 in Figure 5). As a result, the desired image is projected as light with a specific polarization that has high directionality (straight-line propagation) towards the retroreflector 2 via the optical direction conversion panel 54, reflected by the retroreflector 2, and transmitted towards the eyes of a monitor outside the store (space) to form a floating image 3 in space. A protective cover 50 (see Figures 6 and 7) may be provided on the surface of the optical direction conversion panel 54 described above.

[0111] <Example of a display device 1> Figure 6 shows an example of the specific configuration of the display device 1. In Figure 6, a liquid crystal display panel 11 and a light direction conversion panel 54 are arranged on top of the light source device 13 shown in Figure 5. The light source device 13 is formed from, for example, plastic on the case shown in Figure 5, and houses LED elements 201 and a light guide 203 inside. As shown in Figure 5, the end face of the light guide 203 has a lens shape that gradually increases in cross-sectional area toward the light receiving part, and has the effect of gradually decreasing the divergence angle by undergoing multiple total internal reflections as the light propagates through the interior, in order to convert the divergent light emitted from each LED element 201 into a nearly parallel luminous beam. The liquid crystal display panel 11 that constitutes the display device 1 is mounted on the top surface of the display device 1. In addition, an LED (Light Emitting Diode) element 201, which is a semiconductor light source, and an LED substrate 202 on which its control circuit is mounted are attached to one side of the case of the light source device 13 (the left end face in this example). A heat sink, which is a component for cooling the heat generated by the LED elements and control circuit, may be attached to the outer surface of the LED substrate 202.

[0112] Furthermore, the frame (not shown) of the liquid crystal display panel, 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, and further mounting an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is an image display element, generates a display image by modulating the intensity of transmitted light based on a control signal from a control circuit (image control unit 1160 in Figure 3) 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 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 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 light beam from a general light source equipped with an LED element.

[0113] Next, the configuration of the optical system housed within the case of the light source device 13 will be explained in detail with reference to Figure 7, along with Figure 6.

[0114] Since Figures 6 and 7 are cross-sectional views, only one of the multiple LED elements 201 constituting the light source is shown, and these are converted into approximately collimated 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 are mounted while maintaining a predetermined positional relationship.

[0115] Each of these light guides 203 is formed from a translucent resin, such as acrylic. The LED light-receiving surface at the end of the light guide 203 has, for example, a cone-shaped outer surface obtained by rotating a parabolic cross-section, with a recess at its apex that forms a convex portion (i.e., a convex lens surface) in its center, and a convex lens surface (or a concave lens surface that is recessed inward) in the center of its flat surface (not shown). The outer shape of the light-receiving portion of the light guide to which the LED element 201 is attached is a parabolic shape that forms a cone-shaped outer surface, and is set within an angle range that allows for total internal reflection of light emitted from the LED element in the peripheral direction, or a reflective surface is formed.

[0116] On the other hand, the LED elements 201 are each positioned at predetermined locations on the surface of the LED substrate 202, which is their circuit board. The LED substrate 202 is fixed to the LED collimator (light-receiving end face 203a) such that the LED elements 201 on its surface are each positioned in the center of the aforementioned recess.

[0117] 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.

[0118] 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 face of a 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 on the end face of the light guide, and guided through the inside of the light guide 203 (in the direction parallel to the drawing) as shown by the arrows. The light beam direction conversion means 204 then emits the light towards the liquid crystal display panel 11, which is arranged approximately parallel to the light guide 203 (in the direction perpendicular to the viewer in the drawing). 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, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled.

[0119] The aforementioned light beam direction conversion means 204, by the shape of the surface of the light guide or by providing, for example, a portion with a different refractive index inside the light guide, emits the light beam propagated within the light guide toward the liquid crystal display panel 11, which is positioned approximately parallel to the light guide 203 (in a direction perpendicular to the viewer in the drawing). 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 is no practical problem, and if it exceeds 30%, it is an even better characteristic.

[0120] Figure 6 is a cross-sectional diagram illustrating the configuration and operation of the light source in this embodiment, which performs polarization conversion, in the light source device 13 including the light guide 203 and LED element 201 described above. In Figure 6, 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, which is formed of plastic or the like, an LED element 201 as a light source, a reflective sheet 205, a phase difference plate 206, 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 its upper surface.

[0121] Furthermore, a film or sheet-like reflective polarizer 49 is provided on the light source light incidence surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, selectively reflecting one side of the polarization (e.g., P-wave) 212 of the natural light beam 210 emitted from the LED element 201. The reflected light is reflected again by a reflective sheet 205 provided on one side (lower surface in the figure) of the light guide 203 and directed towards the liquid crystal display panel 11. Therefore, a phase difference plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizer 49, causing the reflected light beam to be reflected by the reflective sheet 205 and passed through twice, converting the reflected light beam from P-polarization to S-polarization and improving the efficiency of utilizing the light source light as image light. The image light beam whose light intensity has been modulated by the image signal in the liquid crystal display panel 11 (arrow 213 in Figure 6) is incident on the retroreflector 2. After reflection by the retroreflector 2, a spatially floating image, which is a real image, can be obtained.

[0122] Figure 7, similar to Figure 6, is a cross-sectional arrangement diagram illustrating the configuration and operation of the light source in this embodiment, which performs polarization conversion, in a light source device 13 including a light guide 203 and an LED element 201. The light source device 13 is similarly composed of a light guide 203 with a light beam direction conversion means 204 provided on the surface or inside, for example, made of plastic, an LED element 201 as a light source, a reflective sheet 205, a phase difference plate 206, a lenticular lens, and the like. A liquid crystal display panel 11, equipped with polarizing plates on the light source light incident surface and the image light emission surface, is mounted on the upper surface of the light source device 13 as an image display element.

[0123] Furthermore, a film or sheet-like reflective polarizer 49 is provided on the light source light incidence surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, selectively reflecting one side of the polarization (e.g., S-wave) 211 of the natural light beam 210 emitted from the LED element 201. That is, in the example of Figure 7, the selective reflection characteristics of the reflective polarizer 49 are different from those in Figure 7. The reflected light is reflected by a reflective sheet 205 provided on one side (lower surface in the figure) of the light guide 203 and returns to the liquid crystal display panel 11. A phase difference plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizer 49, causing the reflected light beam to be reflected by the reflective sheet 205 and passed through twice, thereby converting the reflected light beam from S-polarization to P-polarization and improving the utilization efficiency of the light source light as image light. The image light beam whose light intensity has been modulated by the image signal in the liquid crystal display panel 11 (arrow 214 in Figure 7) is incident on the retroreflector 2. After reflection by retroreflector 2, a real image, which is a floating image in space, can be obtained.

[0124] In the light source devices shown in Figures 6 and 7, in addition to the action of the polarizer provided on the light incident surface of the corresponding liquid crystal display panel 11, a reflective polarizer 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 and the reciprocal of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel. 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.

[0125] <Example of display device 2> Figure 8 shows another example of the specific configuration of the display device 1. This light source device 13 is constructed by housing LEDs, a collimator, a composite diffusion block, a light guide, etc., in a case made of, for example, plastic, and a liquid crystal display panel 11 is mounted on its top surface. In addition, an LED substrate on which semiconductor light source LED (Light Emitting Diode) elements 14a and 14b and their control circuits are mounted is attached to one side of the case of the light source device 13, and a heat sink 103, which is a component for cooling the heat generated by the LED elements and control circuits, is attached to the outer surface of the LED substrate.

[0126] Furthermore, the liquid crystal display panel frame attached to the top surface of the case is configured with a liquid crystal display panel 11 attached to the frame, and an FPC (Flexible Printed Circuits) 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 here) that constitutes an electronic device, together with LED elements 14a and 14b, which are solid light sources.

[0127] <Example of a display device 3> Next, using Figure 9, another example of the specific configuration of the display device 1 (Example 3 of the display device) will be explained. In this display device 1, the light source device converts the divergent luminous flux of light from the LED (a mixture of P-polarized and S-polarized light) into a nearly parallel luminous flux by the collimator 18, and reflects it toward the liquid crystal display panel 11 by the reflective surface of the reflective light guide 304. The reflected light is incident on a reflective polarizer 49 placed between the liquid crystal display panel 11 and the reflective light guide 304. The reflective polarizer 49 transmits light of a specific polarization (e.g., P-polarized light), and the transmitted polarized light is incident on the liquid crystal display panel 11. Here, other polarizations other than the specific polarization (e.g., S-polarized light) are reflected by the reflective polarizer 49 and return to the reflective light guide 304.

[0128] The reflective polarizer 49 is installed at an angle to the liquid crystal display panel 11 so as not to be perpendicular to the principal ray of light from the reflective surface of the reflective light guide 304. The principal ray of light reflected by the reflective polarizer 49 is incident on the transmissive surface of the reflective light guide 304. The light incident on the transmissive surface of the reflective light guide 304 passes through the back of the reflective light guide 304, passes through the λ / 4 plate 270 which is a phase difference plate, and is reflected by the reflector 271. The light reflected by the reflector 271 passes through the λ / 4 plate 270 again and passes through the transmissive surface of the reflective light guide 304. The light that has passed through the transmissive surface of the reflective light guide 304 is incident on the reflective polarizer 49 again.

[0129] At this time, the light that again enters the reflective polarizer 49 has passed through the λ / 4 plate 270 twice, so its polarization has been converted to a polarization that can be transmitted through the reflective polarizer 49 (for example, P-polarization). Therefore, the light whose polarization has been converted passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Regarding the polarization design related to polarization conversion, it is also acceptable to configure the polarization in reverse from the above explanation (reversing S-polarization and P-polarization).

[0130] As a result, the light from the LEDs 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, multiple LEDs constituting the light source are shown (however, only one is shown in Figure 9 because it is a vertical cross-section), and these are mounted in predetermined positions relative to the collimator 18.

[0131] Each collimator 18 is formed from a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer surface obtained by rotating a parabolic cross-section. The collimator 18 may also have a recess with a convex portion (i.e., a convex lens surface) in the center of the top portion (the side facing the LED substrate 102). Furthermore, the central part of the planar portion of the collimator 18 (the side opposite to the top portion) has a convex lens surface that protrudes outward (or a concave lens surface that is recessed inward). The parabolic surface forming the cone-shaped outer surface of the collimator 18 is set within an angle range that allows for total internal reflection of light emitted from the LED in the peripheral direction, or a reflective surface is formed thereon.

[0132] The LEDs are each positioned at predetermined locations on the surface of the LED board 102, which is the circuit board for the LEDs. The LED board 102 is fixed to the collimator 18 such that the LEDs on its surface are each positioned at the center of the apex of the cone-shaped convex form (or in the recess if there is a recess at the apex).

[0133] With this configuration, the collimator 18 focuses the light emitted from the LED, particularly the light emitted from its central portion, into parallel light due to the convex lens surface that forms the outer shape of the collimator 18. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface that forms the conical outer surface of the collimator 18, and is also focused into parallel light. In other words, a collimator 18 with a convex lens in its center and a parabolic surface around its periphery makes it possible to extract almost all of the light generated by the LED as parallel light, thereby improving the utilization efficiency of the generated light.

[0134] Furthermore, the light converted to nearly parallel light by the collimator 18 shown in Figure 9 is reflected by the reflective light guide 304. Of this light, light of a specific polarization is transmitted through the reflective polarizer 49, and the light of the other polarization reflected by the reflective polarizer 49 is transmitted through the light guide 304 again. This light is reflected by the reflector 271 located opposite the liquid crystal display panel 11 to the reflective light guide 304. At this time, the light undergoes polarization conversion by passing through the λ / 4 plate 270, which is a phase difference plate, twice. The light reflected by the reflector 271 is transmitted through the light guide 304 again and incident on the reflective polarizer 49 located on the opposite side. Since the polarization conversion has been performed on this incident light, it is transmitted through the reflective polarizer 49, its polarization direction is aligned, and it is incident on the liquid crystal display panel 11. As a result, all of the light from the light source can be utilized, so the geometrical optical utilization efficiency of the light is doubled. Furthermore, since the polarization degree (extinction ratio) of the reflective polarizer is also added to the extinction ratio of the entire system, the contrast ratio of the entire display device is significantly improved by using the light source device of this embodiment. The reflection and diffusion angles of light at each reflective surface can be adjusted by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 should be adjusted for each design to further optimize the uniformity of the light incident on the liquid crystal display panel 11.

[0135] Note that the λ / 4 plate 270, which is the phase difference plate in Figure 9, does not necessarily need to have a phase difference of λ / 4 with respect to polarization incident perpendicularly to the λ / 4 plate 270. In the configuration of Figure 9, any phase difference plate that changes its phase by 90° (λ / 2) after the polarization passes through it twice is sufficient. The thickness of the phase difference plate should be adjusted according to the incident angle distribution of the polarization.

[0136] <Example of a display device 4> Furthermore, another example of the optical system configuration for the light source device of a display device (Example 4 of a display device) will be explained using Figure 10. This is an example of a configuration in which a diffusion sheet is used instead of the reflective light guide 304 in the light source device of Example 3 of a display device. Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) that convert the diffusion characteristics in the vertical and horizontal directions (front and back directions in the figure, not shown) are used on the light output side of the collimator 18, and the light from the collimator 18 is incident between the two optical sheets (diffusion sheet).

[0137] Note that the optical sheet described above may be a single sheet instead of two. If a single sheet is used, the vertical and horizontal diffusion characteristics are adjusted by the micro-shapes of the front and back surfaces of the single optical sheet. Alternatively, multiple diffusion sheets may be used to share the function. In the example shown in Figure 10, the reflection and diffusion characteristics of optical sheets 207A and 207B are optimized by designing the number of LEDs, the divergence angle from the LED substrate (optical element) 102, and the optical specifications of the collimator 18 as design parameters so that the surface density of the light beam emitted from the liquid crystal display panel 11 is uniform. In other words, the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of a light guide.

[0138] In the example shown in Figure 10, polarization conversion is performed in the same manner as in Example 3 of the display device described above. That is, in the example shown in Figure 10, the reflective polarizer 49 should be configured to have the characteristic of reflecting S-polarized light (and transmitting P-polarized light). In that case, P-polarized light from the light source LED is transmitted, and the transmitted light is incident on the liquid crystal display panel 11. S-polarized light from the light source LED is reflected, and the reflected light passes through the phase difference plate 270 shown in Figure 10. The light that has passed through the phase difference plate 270 is reflected by the reflector 271. The light reflected by the reflector 271 is converted to P-polarized light by passing through the phase difference plate 270 again. The polarized light passes through the reflective polarizer 49 and is incident on the liquid crystal display panel 11.

[0139] Note that the λ / 4 plate 270, which is the phase difference plate in Figure 10, does not necessarily need to have a phase difference of λ / 4 with respect to polarization incident perpendicularly to the λ / 4 plate 270. In the configuration of Figure 10, any phase difference plate that changes its phase by 90° (λ / 2) after the polarization passes through it twice is sufficient. The thickness of the phase difference plate should be adjusted according to the incident angle distribution of the polarization. Also, in Figure 10, regarding the polarization design related to polarization conversion, the polarization can be reversed from the explanation above (S-polarization and P-polarization are reversed).

[0140] In typical TV applications, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in both the horizontal direction (shown on the X-axis in Figure 12(a)) and the vertical direction (shown on the Y-axis in Figure 12(b)). In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel in this embodiment are such that, for example, as shown in Example 1 in Figure 12, 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 62 degrees of a typical TV application. Similarly, the vertical viewing angle is made uneven, with the upper viewing angle being reduced to about 1 / 3 of the lower viewing angle by optimizing the reflection angle of the reflective light guide and the area of ​​the reflective surface. As a result, compared to conventional liquid crystal TVs, the amount of image light directed towards the viewing direction is significantly improved, and the brightness is more than 50 times higher.

[0141] Furthermore, with the viewing angle characteristics shown in Example 2 of Figure 12, 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 62 degrees of a typical TV device. 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 typical TV device. As a result, the amount of image light directed towards the monitoring direction is significantly improved compared to conventional LCD TVs, and the brightness becomes more than 100 times higher.

[0142] As described above, by narrowing the viewing angle, the amount of light flux directed towards the monitoring direction can be concentrated, significantly improving the efficiency of light utilization. As a result, even when using a liquid crystal display panel for general TV applications, by controlling the light diffusion characteristics of the light source device, a significant increase in brightness can be achieved with similar power consumption, making it possible to create a video display device that is suitable for information display systems for bright outdoor environments.

[0143] When using a large LCD display panel, the overall brightness of the screen can be improved by directing the light from the edges of the screen inward so that it is directed towards the monitor when the monitor is facing the center of the screen. Figure 11 shows the convergence angles of the long and short sides of the panel, with the monitor's distance L from the panel and the panel size (screen aspect ratio 16:10) as parameters. When monitoring with the screen in portrait orientation, the convergence angle should be set to match the short side. For example, with a 22" panel used vertically and a monitoring distance of 0.8m, setting the convergence angle to 10 degrees will effectively direct the video light from the four corners of the screen towards the monitor.

[0144] Similarly, when monitoring with a 15" panel in portrait orientation, if the monitoring distance is 0.8m, a convergence angle of 7 degrees allows the image light from all four corners of the screen to be effectively directed towards the monitor. As described above, depending on the size of the LCD display panel and whether it is used vertically or horizontally, the overall brightness of the screen can be improved by directing the image light from the periphery of the screen towards the monitor who is in the optimal position to monitor the center of the screen.

[0145] In its basic configuration, as shown in Figure 9, a light source device emits a light beam with narrow-angle directional characteristics onto the liquid crystal display panel 11. By modulating the brightness in accordance with the video signal, the video information displayed on the screen of the liquid crystal display panel 11 is reflected by a retroreflector, and the resulting floating image is displayed outdoors or indoors via a transparent member 100.

[0146] By using the display device and light source device according to one embodiment of the present invention described above, it becomes possible to realize a spatial floating image display device with higher light utilization efficiency.

[0147] <Example of video display processing in a spatially floating video display device> Next, an example of a problem that the image processing of this embodiment solves will be explained using Figure 13A. In the floating spatial image display device 1000, when the area behind the floating spatial image 3 is inside the housing of the floating spatial image display device 1000 as seen from the user's perspective, and is sufficiently dark, the user perceives the background of the floating spatial image 3 as black.

[0148] Here, using Figure 13A, we will explain an example of displaying the character "Panda" 1525 in the floating spatial image 3. First, the image control unit 1160 in Figure 3 recognizes the pixel area for drawing the image of the character "Panda" 1525 and the transparent information area 1520, which is the background image, in an image that includes both the pixel area for drawing the image of the character "Panda" 1525 and the transparent information area 1520, which is the background image, as shown in Figure 13A(1).

[0149] One method for distinguishing and recognizing character images and background images is to configure the image processing of the video control unit 1160 so that the background image layer and the character image layer in front of the background image layer can be processed as separate layers, and the character images and background images can be distinguished and recognized based on the superposition relationship when these layers are combined.

[0150] Here, the video control unit 1160 recognizes the black pixels that render objects such as character images and the transparent information pixels as different information. However, it is assumed that both the black pixels that render objects and the transparent information pixels have a brightness of 0. In this case, when displaying the floating spatial image 3, there is no difference in brightness between the pixels that render black in the image of the character "panda" 1525 and the pixels of the transparent information area 1520, which is the background image. Therefore, in the floating spatial image 3, as shown in Figure 13A(2), neither the pixels that render black in the image of the character "panda" 1525 nor the pixels of the transparent information area 1520 have brightness, and are optically perceived by the user as the same black space. In other words, the parts of the image of the character "panda" 1525 that are rendered in black blend into the background, and only the non-black parts of the character "panda" 1525 are perceived as floating in the display area of ​​the floating spatial image 3.

[0151] An example of image processing in this embodiment will be explained using Figure 13B. Figure 13B illustrates an example of image processing that more effectively resolves the problem described in Figure 13A, where the black image area of ​​an object blends into the background. In Figures 13B(1) and (2), the display state of the floating spatial image 3 is shown on the upper side, and the input / output characteristics of the image processing of the object's image are shown on the lower side. The image of the object (character "Panda" 1525) and its corresponding data may be read from the storage unit 1170 or memory 1109 in Figure 3. Alternatively, it may be input from the video signal input unit 1131. Alternatively, it may be acquired via the communication unit 1132.

[0152] In the state shown in Figure 13B(1), the input / output characteristics of the image processing of the object's image are in a linear state with no special adjustments. In this case, the display state is the same as in Figure 13A(2), and the black image area of ​​the object blends into the background. In contrast, in Figure 13B(2), the video control unit 1160 of this embodiment adjusts the input / output characteristics of the image processing of the object (character "Panda" 1525) to the input / output characteristics shown in the lower section.

[0153] In other words, the video control unit 1160 performs input-output characteristic image processing on the image of the object (character "Panda" 1525), which has the characteristic of converting the pixels of the input image into output pixels with increased brightness values ​​for pixels in the low-brightness region. After the image of the object (character "Panda" 1525) is subjected to this input-output characteristic image processing, the video including the image of the object (character "Panda" 1525) is input to the display device 1 and displayed. As a result, the display state of the floating video 3 is as shown in the upper part of Figure 13B(2), where the brightness of the pixel regions that draw black in the image of the character "Panda" 1525 increases. This makes it possible to distinguish the regions that draw black within the area where the image of the character "Panda" 1525 is drawn from the black background and allow the user to recognize it, making it possible to display the object more favorably.

[0154] In other words, by using the image processing shown in Figure 13B(2), the area displaying the image of the object character "Panda" 1525 can be distinguished from the black background inside the housing of the floating image display device 1000 via the window, thereby improving the visibility of the object. Therefore, for example, even if an object contains pixels with a brightness value of 0 before the image processing (i.e., when the image of the object and its corresponding data are read from the storage unit 1170 or memory 1109 in Figure 3, or when the image of the object is input from the video signal input unit 1131, or when the data of the object is acquired via the communication unit 1132, etc.), the image processing of the input / output characteristics by the video control unit 1160 converts it into an object with increased brightness values ​​in the low-brightness region, which is then displayed on the display device 1 and converted into a floating image 3 by the optical system of the floating image display device 1000.

[0155] In other words, the pixels constituting the object after image processing of the input / output characteristics are converted to a state in which no pixels with a brightness value of 0 are included, and then displayed on the display device 1, and converted into a floating image 3 by the optical system of the floating image display device 1000.

[0156] Furthermore, in the image processing shown in Figure 13B(2), one method for applying the input / output characteristics image processing shown in Figure 13B(2) only to the area of ​​the object (character "Panda" 1525) image is to configure the image processing of the video control unit 1160 so that the background image layer and the character image layer in front of the background image layer can be processed as separate layers, and the input / output characteristics image processing shown in Figure 13B(2) can be applied to the character image layer, while the background image layer can not be processed in the same way.

[0157] Subsequently, when these layers are combined, as shown in Figure 13B(2), only the character image will be subjected to image processing that enhances the low-luminance areas of the input image. Alternatively, the character image layer and the background image layer may be combined first, and then the image processing with the input / output characteristics shown in Figure 13B(2) may be applied only to the character image area.

[0158] Furthermore, the input / output video characteristics used in video processing to enhance the low-luminance region of the input / output characteristics for the input video are not limited to the example shown in Figure 13B(2). Any video processing that enhances low luminance is acceptable, including so-called bright adjustment. Alternatively, video processing that improves visibility may be performed by controlling the gain that changes the weighting of the retinex processing, as disclosed in International Publication No. 2014 / 162533.

[0159] As explained above, the image processing shown in Figure 13B(2) allows for the rendering of black areas within the image rendering area, such as characters and objects, to be recognized by the user without blending into the black background, thereby achieving a more suitable display.

[0160] In the examples shown in Figures 13A and 13B, the challenges and more suitable image processing methods were explained using examples of spatial levitation image display devices where the background appears black (for example, the spatial levitation image display device 1000 in Figures 4A-G, or the spatial levitation image display device 1000 in Figures 4I and 4J with the rear window shading). However, this image processing method is also effective for devices other than these spatial levitation image display devices.

[0161] Specifically, in the floating image display device 1000 shown in Figure 4H, and in the floating image display device 1000 shown in Figures 4I and 4J with the rear window not shading, the background of the floating image 3 is not black, but rather the scenery behind the floating image display device 1000 through the window. In this case as well, the problems described in Figures 13A and 13B still exist.

[0162] In other words, the parts of the image of the character "Panda" 1525 that are rendered in black blend into the scenery behind the floating video display device 1000 through the window. In this case as well, by using the image processing shown in Figure 13B(2), the parts of the image of the character "Panda" 1525 that are rendered in black can be distinguished and recognized from the scenery behind the floating video display device 1000 through the window, thereby improving the visibility of the object.

[0163] In other words, by using the image processing shown in Figure 13B(2), the area displaying the image of the object character "Panda" 1525 can be distinguished from the scenery behind the spatially floating image display device 1000 through the window, making it more favorable to recognize that the object character "Panda" 1525 is in front of the scenery, thereby improving the visibility of the object.

[0164] Furthermore, in the floating image display device 1000 shown in Figures 4K, 4L, and 4M, as described above, if another image (such as the image from the transmissive self-emissive image display device 1650 or the image from the second display device 1680) is displayed at a different depth from the floating image 3, the background of the floating image 3 will not be black, but will be that other image. In this case as well, the problems described in Figures 13A and 13B still exist.

[0165] In other words, the parts of the image of the object character "Panda" 1525 that are rendered in black blend into the other image which is displayed at a different depth from the floating spatial image 3. In this case as well, by using the image processing shown in Figure 13B(2), the parts of the image of the object character "Panda" 1525 that are rendered in black can be distinguished and recognized from the other image, thereby improving the visibility of the object.

[0166] In other words, by using the image processing shown in Figure 13B(2), the area displaying the image of the object character "Panda" 1525 can be recognized separately from the other video, making it more favorable to recognize that the object character "Panda" 1525 is in front of the other video, thereby improving the visibility of the object.

[0167] An example of the video display processing in this embodiment will be explained using Figure 13C. Figure 13C is an example of video display in this embodiment in which the floating video 3 and a second image 2050, which is another video, are displayed simultaneously. The second image 2050 may correspond to the display video of the transmissive self-emissive video display device 1650 in Figure 4K or Figure 4L. Alternatively, the second image 2050 may correspond to the display video of the second display device 1680 in Figure 4M.

[0168] In other words, the example of video display in Figure 13C is a concrete example of the video display example of the spatial floating video display device 1000 shown in Figures 4K, 4L, and 4M. In this example, a bear character is displayed in spatial floating video 3. Areas other than the bear character in spatial floating video 3 are displayed in black and are transparent as spatial floating video. The second image 2050 is a background image depicting a plain, mountains, and the sun.

[0169] In Figure 13C, the floating image 3 and the second image 2050 are displayed at different depths. By viewing the two images, floating image 3 and the second image 2050, in the line of sight indicated by arrow 2040, user 230 can see the two images superimposed. Specifically, the bear character from floating image 3 appears superimposed in front of the background of plains, mountains, and the sun depicted in the second image 2050.

[0170] Here, since the floating image 3 is projected as a real image in the air, when user 230 slightly moves their viewpoint, they can perceive the depth of the floating image 3 and the second image 2050 due to parallax. Therefore, user 230 can view the two images superimposed and obtain a stronger sense of floating in the floating image 3.

[0171] An example of the video display processing in this embodiment will be explained using Figure 13D. Figure 13D(1) is a view of the floating-in-space video 3 from the user 230's line of sight, as seen in the example of video display in this embodiment shown in Figure 13C. Here, a bear character is displayed in the floating-in-space video 3. Areas other than the bear character in the floating-in-space video 3 are displayed in black and are transparent as a floating-in-space video.

[0172] Figure 13D(2) is a view of the second image 2050 from the user 230's line of sight, as seen in the example of video display of this embodiment in Figure 13C. In this example, the second image 2050 is a background image depicting a plain, mountains, and the sun.

[0173] Figure 13D(3) shows an example of the video display in this embodiment of Figure 13C, where the second image 2050 and the floating spatial image 3 appear superimposed in the user 230's line of sight. Specifically, the bear character from the floating spatial image 3 appears superimposed in front of the background of plains, mountains, and the sun depicted in the second image 2050.

[0174] Here, when displaying the floating image 3 and the second image 2050 simultaneously, it is desirable to pay attention to the balance of brightness between the two images in order to better ensure the visibility of the floating image 3. If the second image 2050 is too bright compared to the brightness of the floating image 3, the displayed image of the floating image 3 will become transparent, and the background, the second image 2050, will become transparent and strongly visible.

[0175] Therefore, the output of the light source for the floating image 3 and the display image brightness of the display device 1, as well as the output of the light source of the display device that displays the second image 2050 and the display image brightness of the display device, should be set such that the brightness per unit area of ​​the floating image 3 at the display position of the floating image 3 is greater than the brightness per unit area of ​​the image light reaching the display position of the floating image 3 from the second image 2050.

[0176] Furthermore, since this condition only needs to be met when the floating image 3 and the second image 2050 are displayed simultaneously, when switching from the first display mode, which displays only the second image 2050 without displaying the floating image 3, to the second display mode, which displays the floating image 3 and the second image 2050 simultaneously, control may be performed to reduce the brightness of the second image 2050 by lowering the output of the light source of the display device that displays the second image 2050 and / or the display image brightness of the display device. These controls can be achieved by the control unit 1110 in Figure 3 controlling the display device 1 and the display device that displays the second image 2050 (the transmissive self-emissive image display device 1650 in Figure 4K or Figure 4L, or the second display device 1680 in Figure 4M).

[0177] Furthermore, when switching from the first display mode to the second display mode described above, if control is performed to reduce the brightness of the second image 2050, the brightness may be reduced uniformly across the entire screen of the second image 2050. Alternatively, instead of uniformly reducing the brightness across the entire screen of the second image 2050, the area where an object is displayed in the floating spatial image 3 may be set to the state with the highest brightness reduction effect, and the brightness reduction effect may be gradually reduced in the surrounding areas. In other words, if the brightness reduction of the second image 2050 is achieved only in the area where the floating spatial image 3 is superimposed on the second image 2050 and visible, the visibility of the floating spatial image 3 can be sufficiently ensured.

[0178] Here, since the floating image 3 and the second image 2050 are displayed at different depths, if the user 230 slightly changes their viewpoint, the superimposed position of the floating image 3 on the second image 2050 changes due to parallax. Therefore, when switching from the first display mode to the second display mode described above, if the brightness is to be reduced unevenly across the entire screen of the second image 2050, it is not desirable to sharply reduce the brightness based on the outlines of the objects displayed in the floating image 3. Rather, it is desirable to perform a gradient processing of the brightness reduction effect, which changes the brightness reduction effect step by step depending on the position, as described above.

[0179] In the case of the floating image display device 1000, where the position of the object displayed in the floating image 3 is approximately in the center of the floating image 3, the position where the brightness reduction effect of the gradient processing is highest should be the center of the floating image 3.

[0180] According to the video display processing of this embodiment described above, the user 230 can more favorably view the floating video 3 and the second image 2050.

[0181] Furthermore, when displaying the floating image 3, the display of the second image 2050 may be controlled to be disabled. Disabling the display of the second image 2050 improves the visibility of the floating image 3, making it suitable for floating image display devices 1000 and other applications where the user must reliably view the floating image 3 when it is displayed.

[0182] <Example 2> As Embodiment 2 of the present invention, an example of a foldable configuration for a floating spatial image display device will be described. The floating spatial image display device according to this embodiment is a modified version of the floating spatial image display device described in Embodiment 1, with the configuration changed to a foldable configuration. In this embodiment, the differences from Embodiment 1 will be explained, and similar configurations and similarities will not be repeated. In the following description of the embodiment, the expression "storage" does not only mean completely fitting an element into a certain place. That is, even if an element is partially fitted into a certain place and partially exposed, it is still described as "storage". Therefore, it is acceptable to read "storage" as "holding". In this case, "to store" can be read as "holding", and "to be stored" can be read as "to be held".

[0183] Figure 14A shows an example of a foldable floating image display device 1000. The floating image display device 1000 in Figure 14A has multiple housings, housing A1711 and housing B1712. Housings A1711 and B1712 are connected via a polarizing mirror holder 1750 that holds a polarizing separation member 101B, which is a polarizing mirror. A rotating mechanism 1751 is provided at the connection between the polarizing mirror holder 1750 and housing A1711, and the rotation function of the rotating mechanism 1751 allows the relative angle between the polarizing mirror holder 1750 (and polarizing separation member 101B) and housing A1711 to be changed. A rotating mechanism 1752 is provided at the connection between the polarizing mirror holder 1750 and the housing B1712, and the rotation function of the rotating mechanism 1752 allows the relative angle between the polarizing mirror holder 1750 (and the polarizing separation member 101B) and the housing B1712 to be changed.

[0184] Here, we will describe the state in which the housing A1711, housing B1712, and polarization separation member 101B are positioned in front of the user 230 at an angle that forms the letter N as shown in Figure 14A(1) (usage state). This arrangement of housing A1711, housing B1712, and polarization separation member 101B at this angle may also be referred to as the N-shaped arrangement.

[0185] In the following embodiments, various configurations, functions, and modifications of the foldable floating image display device 1000 will be described. In these descriptions, the various configurations, functions, and modifications other than those limited to the folding function can also be used for various configurations, functions, and modifications of a floating image display device with an N-shaped arrangement. In other words, these various configurations, functions, and modifications are also effective for floating image display devices with an N-shaped arrangement that do not have a folding function.

[0186] Here, the display device 1, which has a light source device (hereinafter also simply called the light source) 13 and a liquid crystal display panel 11, displays an image, and the image light from the display device 1 is emitted to the polarization separation member 101B. Of the image light from the display device 1, the light that passes through the polarization separation member 101B passes through the λ / 4 plate 21, is reflected by the retroreflector 2, passes through the λ / 4 plate 21 again, and is emitted to the polarization separation member 101B. The light emitted from the λ / 4 plate 21, incident on the polarization separation member 101B, and reflected by the polarization separation member 101B forms a floating image 3.

[0187] The details of the optical system in this embodiment for forming the floating image 3 have already been explained in Figures 2 and 4 of Embodiment 1, so a repeated explanation will be omitted. The details of the light source 13 of the display device 1 in this embodiment have already been explained in Figures 5 to 12 of Embodiment 1, so a repeated explanation will be omitted.

[0188] As explained in Figures 2 and 4 of Example 1, an absorbing polarizing plate 12 may be provided on the image display surface of the liquid crystal display panel 11. The spatial levitation image display device of this embodiment may be configured to have the elements shown in the internal block diagram of Figure 3. In this case, each element shown in the housing 1190 of Figure 3 may be configured to be housed or held in any of the parts of housing A1711, housing B1712, and polarizing mirror holder 1750.

[0189] However, if elements requiring wiring of power supply lines from power supply 1106 in Figure 3 (various circuit boards, various processing units, various interfaces, various sensors, etc.) and elements requiring wired connection to control unit 1110 are separated and placed in housings A1711 and B1712, the wiring of power supply lines and wired control signal lines will be required through the internal structures of the rotating mechanism 1751, rotating mechanism 1752, and polarizing mirror holder 1750, resulting in a complex structure.

[0190] Therefore, it is preferable to configure the components that require power supply and components that require wired signal line connections to be housed in the housing A1711, which houses the display device 1 that always requires power supply. In this case, wiring of power supply lines and wired control signal lines through the internal structures of the rotating mechanism 1751, the rotating mechanism 1752, and the polarizing mirror holder 1750 becomes unnecessary, and the floating spatial image display device 1000 can be provided at a lower cost. For the same reason, it is preferable to house the power supply 1106 and the secondary battery 1112 in the housing A1711, which houses the display device 1 that has a power supply that is driven using these power sources.

[0191] Here, when the floating image display device 1000 is positioned in the operating state shown in Figure 14A(1), the optical path from the display device 1 to the floating image 3 via the retroreflective plate 2 requires a predetermined optical path length. Therefore, in the operating state, the floating image display device 1000 requires a predetermined volume of space between the housing A1711 and the opposing housing B1712, which includes at least the range of the light beam in the optical path of the image light reaching from the display device 1 to the retroreflective plate 2.

[0192] In each of the floating image display devices 1000 in the first embodiment of the present invention, for example, Figure 4, even when the floating image display device 1000 is not in use, a predetermined volume of space including the range of the light beam in the optical path of the image light reaching from the display device 1 to the retroreflector 2 is maintained within the housing of each floating image display device 1000. Therefore, each of the floating image display devices 1000 in the first embodiment of the present invention, for example, Figure 4, has a large volume even when not in use, and there is room for improvement in terms of portability and storage.

[0193] Therefore, in the operating state, the floating image display device 1000 in Figure 14A is configured such that the relative angles of the housing A1711, housing B1712, and polarization separation member 101B are as shown in Figure 14A(1) so that the image light from the display device 1 forms a floating image 3 in space via the retroreflective plate 2. Specifically, the rotation mechanism 1751 is provided with a stopper to limit the adjustment range of the relative angle between housing A1711 and the polarization mirror holder 1750, and the upper limit of the angle at which housing A1711 and the polarization mirror holder 1750 open is the angle shown in Figure 14A(1).

[0194] Furthermore, the rotating mechanism 1752 may be configured to include a stopper to limit the adjustment range of the relative angle between the housing B1712 and the polarizing mirror holder 1750, so that the upper limit of the angle at which the housing B1712 and the polarizing mirror holder 1750 open is the angle shown in Figure 14A(1). The rotating mechanism 1751, the rotating mechanism 1752, and the stopper may be constructed using existing technology.

[0195] Furthermore, the floating image display device 1000 in Figure 14A is configured such that the housing A1711 can be rotated in the direction of the thick arrow shown in Figure 14A(1) by a rotation mechanism 1751, thereby deforming the floating image display device 1000 so that the relative angle between the housing A1711 and the polarizing mirror holder 1750 becomes smaller. Additionally, the housing B1712 can be rotated in the direction of the thick arrow shown in Figure 14A(1) by a rotation mechanism 1752, thereby deforming the floating image display device 1000 so that the relative angle between the housing B1712 and the polarizing mirror holder 1750 becomes smaller. The shape of the floating image display device 1000 after this deformation is shown in Figure 14A(2). Hereinafter, the state in which the floating image display device 1000 is folded, as shown in Figure 14A(2), will be referred to as the folded state.

[0196] Here, the volume obtained by multiplying the maximum width (x direction), maximum depth (y direction), and maximum height (z direction) of the spatial levitation image display device 1000 is defined as the maximum volume of the spatial levitation image display device 1000's external dimensions. The maximum volume of the spatial levitation image display device 1000 in the folded state shown in Figure 14A(2) is smaller than the maximum volume of the spatial levitation image display device 1000 in the usage state shown in Figure 14A(1). Therefore, in the example shown in Figure 14A, when the user 230 uses the spatial levitation image display device 1000, they view the spatial levitation image 3 in the usage state shown in Figure 14A(1), and when the spatial levitation image display device 1000 is not in use, they fold it in the state shown in Figure 14A(2), thereby reducing its maximum volume and making the device easier to carry and store.

[0197] Note that in the folded state shown in Figure 14A(2), it is not possible to form the floating image 3. Therefore, in the folded state, it is not necessary to emit image light from the display device 1, and it is preferable to keep the light source 13 of the display device 1 turned off. The control of turning off the light source 13 of the display device 1 when transitioning from the operating state to the folded state may be performed by the control unit 1110 based on user operation via the operation input unit 1107 in Figure 3.

[0198] Furthermore, an open / close sensor 1741 may be provided to detect whether or not the floating video display device 1000 is in a folded state, as shown in Figures 14A(1) and 14A(2), and the light source 13 of the display device 1 may be controlled to turn off based on the detection result of the open / close sensor. The open / close sensor 1741 may be configured as, for example, a proximity detection sensor using infrared light. The proximity detection sensor may be configured as an active infrared sensor in which the sensor itself emits sensing light such as infrared light, and the sensor detects the reflected light of the sensing light.

[0199] Here, considering the efficiency of wired connections, it is preferable that the open / close sensor 1741, which requires a power supply, be housed in the housing A1711, which houses the display device 1, which always requires a power supply. In this case, the open / close sensor 1741 may detect the distance between the housing A1711 and the polarizing mirror holder 1750 and detect when the floating image display device 1000 is in a folded state according to that distance.

[0200] Alternatively, the opening / closing sensor 1741 may detect the distance between housing A1711 and housing B1712 and detect when the floating spatial image display device 1000 is in a folded state according to that distance. When detecting the distance between housing A1711 and housing B1712, the infrared sensing light emitted by the opening / closing sensor 1741, which is an active infrared sensor, may be configured to pass through the polarization separation member 101B. The sensing light that has passed through the polarization separation member 101B may be reflected by the retroreflective plate 2, pass through the polarization separation member 101B again, and return to the opening / closing sensor 1741.

[0201] In the description of Example 1, the image light forming the floating image 3 passes through the λ / 4 plate 21 twice, before and after reflection by the retroreflective plate 2, and is therefore reflected by the polarization separation member 101B. This differs from the transmission and reflection characteristics of the sensing light emitted by the opening / closing sensor 1741. Therefore, in order to configure the system so that the infrared sensing light emitted by the opening / closing sensor 1741, which is an active infrared sensor, passes through the polarization separation member 101B again and returns to the opening / closing sensor 1741, it is necessary to make the optical characteristics of the polarization separation member 101B different for the visible light, which is the image light forming the floating image 3, and the infrared light, which is the invisible sensing light emitted by the opening / closing sensor 1741, which is an active infrared sensor. For example, in the infrared region, the system may be configured to have a predetermined transmittance of approximately 50% regardless of the polarization state.

[0202] As explained above, by providing the opening / closing sensor 1741, it is possible to more effectively detect when the floating spatial image display device 1000 is in the folded state. Furthermore, when the opening / closing sensor 1741 detects that the floating spatial image display device 1000 is in the folded state, it becomes possible to more effectively control the switching off of the light source 13 of the display device 1.

[0203] Next, Figure 14B shows a perspective view of an example of the floating image display device 1000 arranged in a state of use. In Figure 14B, the floating image display device 1000 of Figure 14A is shown as an example. In the state of use shown in Figure 14B, the housing A1711, housing B1712, and polarization separation member 101B are positioned in front of the user 230 at an angle that forms the letter N, similar to Figure 14A(1). The polarization separation member 101B is held by the polarization mirror holder 1750. The user can view the floating image 3 formed in front of the polarization separation member 101B. In the example shown in this figure, a rabbit character is displayed in the floating image 3. As explained above using Figure 14B, the floating image display device 1000 with folding function of this embodiment allows for the viewing of the floating image 3 in a suitable state of use.

[0204] Next, using Figure 14C, an example of how to assemble the housing A1711, housing B1712, and polarizing mirror holder 1750, which constitute the spatial floating image display device 1000, will be explained. Here, the polarization separation member 101B is held in the polarizing mirror holder 1750. This figure shows the view from the user's perspective in the operating state.

[0205] In the example shown in Figure 14C, the rotating mechanism 1751 and the rotating mechanism 1752 are both hinge-based rotating mechanisms.

[0206] In the example shown in Figure 14C, the rotating mechanism 1751A is the part of the rotating mechanism 1751 that is located on the polarizing mirror holder 1750 side. If the rotating mechanism 1751 is a hinge-type rotating mechanism, then the rotating mechanism 1751A is the hinge tube (shaft cylinder) on the polarizing mirror holder 1750 side. In contrast, the rotating mechanism 1751B is the part of the rotating mechanism 1751 that is located on the housing A1711 side. If the rotating mechanism 1751 is a hinge-type rotating mechanism, then the rotating mechanism 1751B is the hinge tube (shaft cylinder) on the housing A1711 side. As shown by the arrows in the figure, the rotating mechanism 1751A is fitted into the shaded space of the rotating mechanism 1751B, and an axis (not shown) is passed through the hinge tube on the polarizing mirror holder 1750 side and the hinge tube on the housing A1711 side, thereby forming the hinge of the rotating mechanism 1751. As a result, the polarizing mirror holder 1750 and the housing A1711 are connected to each other via the hinge, and their relative angles can be changed by the rotation function of the hinge.

[0207] Next, in the example of Figure 14C, the rotating mechanism 1752A is the part of the rotating mechanism 1752 that is located on the polarizing mirror holder 1750 side. If the rotating mechanism 1752 is a hinge-type rotating mechanism, then the rotating mechanism 1752A is the hinge tube (shaft cylinder) on the polarizing mirror holder 1750 side. In contrast, the rotating mechanism 1752B is the part of the rotating mechanism 1752 that is located on the housing B1712 side. If the rotating mechanism 1752 is a hinge-type rotating mechanism, then the rotating mechanism 1752B is the hinge tube (shaft cylinder) on the housing B1712 side. As shown by the arrows in the figure, the rotating mechanism 1752A is fitted into the shaded space of the rotating mechanism 1752B, and by passing an axis (not shown) through the hinge tube on the polarizing mirror holder 1750 side and the hinge tube on the housing B1712 side, the hinge of the rotating mechanism 1752 can be formed. As a result, the polarizing mirror holder 1750 and the housing B1712 are connected to each other via the hinge, and the relative angle can be changed by the rotation function of the hinge.

[0208] According to the example assembly method described above, a spatial floating image display device 1000 can be assembled by connecting housing A1711, housing B1712, and polarizing mirror holder 1750, and having a configuration that allows the relative angles of each to be changed.

[0209] In the rotating mechanism 1751, a stopper for limiting the adjustment range of the relative angle between the housing A1711 and the polarizing mirror holder 1750 may be configured by providing a protrusion on the shape of the polarizing mirror holder 1750 around the rotating mechanism 1751A, or by providing a protrusion on the shape of the housing A1711 around the rotating mechanism 1751B. When the relative angle between the housing A1711 and the polarizing mirror holder 1750 reaches a desired angle, these protrusions will interfere with other parts, thereby limiting the upper limit of the relative angle. Similarly, in the rotating mechanism 1752, a stopper for limiting the adjustment range of the relative angle between the housing B1712 and the polarizing mirror holder 1750 may be configured by providing a protrusion on the shape of the polarizing mirror holder 1750 around the rotating mechanism 1752A, or by providing a protrusion on the shape of the housing B1712 around the rotating mechanism 1752B. The upper limit of the relative angle between the housing B1712 and the polarizing mirror holder 1750 can be limited by interference between these protrusions and other parts when the relative angle between them reaches a desired angle.

[0210] In the example shown in Figure 14C, a hinge mechanism was described as an example of a rotation mechanism. However, the rotation mechanism applicable to the spatial floating image display device 1000 of this embodiment is not limited to a hinge mechanism. Mechanisms with a higher degree of freedom, such as a link mechanism, may also be used.

[0211] Next, using Figure 14D, an example of the configuration of the housing B1712 containing the spatial floating image display device 1000 will be described. Figures 14D(1) and 14D(2) are diagrams of the device in use, viewed from the housing A1711 side.

[0212] Figure 14D(1) shows an example of the configuration of the housing B1712. The housing B1712 is equipped with the rotating mechanism 1752B described in Figure 14C. Also, as shown in the figure, the housing B1712 is equipped with a retroreflective plate 2. The portion of the housing B1712 other than the retroreflective plate 2 on the surface having the retroreflective plate 2 forms a frame portion 1731. When the spatial floating image display device 1000 is in use, if some of the image light from the display device 1 is irradiated onto the frame portion 1731 and reflected by the frame portion 1731, stray light may be generated around the spatial floating image 3. Therefore, it is preferable that the surface of the frame portion 1731 be constructed using a low-reflectivity coating or a low-reflectivity color or material. For example, the surface of the frame portion 1731 may be constructed using black resin. Alternatively, for example, the frame portion 1731 may be covered with black fine hairs. These black materials have low light reflectivity and can reduce stray light.

[0213] Figure 14D(2) shows an example of a modified configuration of the housing B1712. In the example in Figure 14D(2), the difference from the example in Figure 14D(1) is that the frame portion 1732 extends further inward from the user's perspective than the frame portion 1731, and this extended portion is provided with a light-shielding plate area LE. The retroreflective plate 2 is not placed in the light-shielding plate area LE. The surface of the light-shielding plate area LE is preferably constructed using a low-reflectivity coating or a low-reflectivity color or material. The effects of providing the light-shielding plate area LE will be described later.

[0214] Next, using Figure 14E, an example of the configuration of the housing A1711 comprising the spatial floating image display device 1000 will be described. Figures 14E(1) and 14E(2) are diagrams of the operating state as seen from the housing B1712 side.

[0215] Figure 14E(1) shows an example of the configuration of housing A1711. Housing A1711 is equipped with a rotating mechanism 1751B as described in Figure 14C. The front surface of housing A1711 in Figure 14E(1) has the image display surface 1708 of the liquid crystal display panel 11 of the display device 1. A bezel portion 1733 is provided around the image display surface. When the spatial levitation image display device 1000 is in use, if light from outside the device is reflected by the bezel portion 1733, stray light may be generated around the spatial levitation image 3. Therefore, it is preferable that the surface of the bezel portion 1733 be constructed using a low-reflectivity coating or a low-reflectivity color or material. Here, as shown in Figure 14E(1), the image display surface 1708 is included within the range of the orthogonal projection 1709 of the retroreflective plate 2 of housing B1712 onto the surface of housing A1711 that has the image display surface 1708. In the example shown in Figure 14E(1), the placement of the image display surface 1708 on the surface of the housing A1711 is such that it is positioned near the center in both the vertical and horizontal directions with respect to the range of the orthogonal projection 1709 of the retroreflective plate 2.

[0216] Next, Figure 14E(2) shows an example of a modified configuration of the housing A1711. The difference between the example in Figure 14E(2) and the example in Figure 14E(1) is that the placement of the image display surface 1708 on the surface of the housing A1711 is offset vertically (upward) from the center of the orthogonal projection 1709 of the retroreflective plate 2. In other words, the center of the image display surface 1708 is offset vertically from the center of the orthogonal projection 1709 of the retroreflective plate 2. The effect of offsetting the placement of the image display surface 1708 upward (upward) will be described later.

[0217] Next, using Figure 14F, an example of the layout of each element (component) housed in the housing A1711 of the spatial floating image display device 1000 will be described. Figures 14F(1) and 14F(2) are diagrams of the device in use, viewed from the housing B1712 side. Figures 14F(1) and 14F(2) show examples corresponding to Figures 14E(1) and 14E(2), respectively, with the dotted lines indicating the placement positions of each element housed on the back side of the frame portion 1733 shown in Figures 14E(1) and 14E(2).

[0218] First, let's explain the example in Figure 14F(1). In the housing A1711 of Figure 14F(1), the image display surface 1708 is the image display surface of the liquid crystal display panel 11 of the display device 1. Therefore, in the housing A1711, the display device 1 is housed in the area surrounded by the dotted line that encloses the image display surface 1708. Here, if the levitating image display device 1000 is a battery-powered device, the battery 1768 is housed in the housing A1711 at a position lower than the display device 1, as shown in Figure 14F(1). Also, if the levitating image display device 1000 is a device that supports external power input, the power supply circuit 1769 that performs voltage transformation processing for the external power supply is housed at a position lower than the display device 1.

[0219] The battery and power supply circuit have a higher weight density compared to the other elements (components). Therefore, it is preferable to position the battery and power supply circuit lower in the housing A1711 in the vertical direction when in use. This lowers the center of gravity of the floating image display device 1000 in use, resulting in a more stable installation. In other words, it is desirable to position the power supply circuit 1769 and the battery 1768 such that their centers of gravity are lower in the vertical direction than the center of the housing A1711 when the floating image display device 1000 is in use.

[0220] Since the display device 1 is housed in the housing A1711, in order to achieve the above effect, it is preferable that the battery 1768 and the power supply circuit 1769 be positioned vertically below the display device 1 when in use. That is, it is desirable that the center of gravity of the power supply circuit 1769 be positioned vertically lower than the center of gravity of the display device 1. It is also desirable that the center of gravity of the battery 1768 be positioned vertically lower than the center of gravity of the display device 1.

[0221] Next, in the example shown in Figure 14F(1), the housing A1711 houses an input interface board (input IF board) 1763. The input interface board 1763 may be configured to include circuits and terminals corresponding to, for example, the video signal input section 1131, the audio signal input section 1133, the communication section 1132, and the removable media interface (removable media IF) 1134 shown in Figure 3.

[0222] Here, as shown in Figure 14F(1), it is preferable that the input interface board 1763 in the housing A1711 be positioned on the side opposite to the side with the rotation mechanism 1751B (the left side in the figure), with respect to the display device 1. In the housing A1711 in Figure 14F(1), the side opposite to the side with the rotation mechanism 1751B is located towards the back from the user's perspective when the levitation video display device 1000 is in use. By positioning the input interface board 1763 in this way, it becomes possible to place various terminals corresponding to the video signal input section 1131, the audio signal input section 1133, the communication section 1132, and the media slot of the removable media interface 1134 on a side that is not visible to the user when the levitation video display device 1000 is in use.

[0223] To achieve the above effects, it is preferable to position the input interface board 1763 in the housing A1711 at a position that is further back from the user's perspective when the spatial levitation image display device 1000 is in use, relative to the display device 1. Note that "further back from the user's perspective when the spatial levitation image display device 1000 is in use" can also be expressed as the rear side of the housing A1711 from the user's perspective.

[0224] Next, in the example shown in Figure 14F(1), the main circuit board 1762 is located on the rear side of the enclosure A1711, relative to the user, compared to the display device 1. Furthermore, the main circuit board 1762 is positioned above the input interface board 1763 and is located in close proximity to the input interface board 1763.

[0225] The main circuit board 1762 may be configured to include circuits corresponding to, for example, the control unit 1110, non-volatile memory 1108, memory 1109, and video control unit 1160 shown in Figure 3. For example, the video control unit 1160 has the function of processing video input from the video signal input unit 1131. Therefore, it is preferable to place the main circuit board 1762 in close proximity to the input interface board 1763 so that wiring can be arranged efficiently.

[0226] Furthermore, the various terminals on the input interface board 1763 may be configured to allow external connections of cables for receiving or transmitting video signals, audio signals, and other data. In this case, if the input interface board 1763 is positioned vertically upward in the housing A1711 when the levitation video display device 1000 is in use, the cables connected to the various terminals on the input interface board 1763 will be connected vertically upward in the housing A1711 when the levitation video display device 1000 is in use. In this case, if the cables are connected to a high position on the levitation video display device 1000, and a tensile force acts on the levitation video display device 1000 from the cables due to the orientation of the cable wiring when in use, a rotational moment with the bottom surface of the housing A1711 as the pivot point may act, potentially causing the levitation video display device 1000 to tip over.

[0227] Therefore, in the housing A1711, it is preferable to position the input interface board 1763 vertically below the main circuit board 1762, thereby positioning the various terminals on the input interface board 1763 at a lower position on the levitating image display device 1000. At a minimum, it is desirable that the cable connection position to the input interface board 1763, i.e., the position of the cable connection terminals, be positioned vertically lower than the center position of the housing A1711. This reduces the height from the bottom surface of the housing A1711 to the cable connection position even when cables are connected to the various terminals on the input interface board 1763, thereby reducing the rotational moment with the bottom surface of the housing A1711 as the pivot point due to the tensile force from the cables, and thus preventing the levitating image display device 1000 from tipping over.

[0228] In the example shown in Figure 14F(1), an opening / closing sensor 1741 is provided on the housing A1711. The opening / closing sensor 1741 is a sensor that detects whether the spatial floating image display device 1000 is in a folded state or not, and can be configured as a proximity sensor using infrared or far-infrared light, and the control unit 1110 in Figure 3, which is provided on the main circuit board 1762, performs various controls according to the sensing result of the opening / closing sensor 1741. Therefore, the wiring arrangement is made more efficient by arranging the opening / closing sensor 1741 on the main circuit board 1762 as in the example shown in Figure 14F(1). As shown for the opening / closing sensor 1741, a transmissive window that allows the sensing light used by the opening / closing sensor 1741 to pass through can be provided on the frame of the housing A1711.

[0229] Next, in the example shown in Figure 14F(1), the housing A1711 houses the backlight drive board 1761. The backlight drive board 1761 supplies a drive voltage to the light source device 13, which is the backlight of the display device 1. The backlight drive board 1761 is controlled by the control unit 1110 shown in Figure 3, which is located on the main circuit board 1762. In the example shown in Figure 14F(1), the backlight drive board 1761 is positioned adjacent to the top of the display device 1 and adjacent to the right of the main circuit board 1762. This ensures that the backlight drive board 1761 is adjacent to both the display device 1 and the main circuit board 1762, thus streamlining the wiring arrangement.

[0230] As explained above, in the example shown in Figure 14F(1), the battery 1768 or power supply circuit 1769, input interface board 1763, main circuit board 1762, and backlight drive board 1761 are arranged on the back side of the frame portion 1733 surrounding the display device 1 in the housing A1711. This makes it possible to efficiently utilize the space on the back side of the frame portion 1733 in the housing A1711, and makes it possible to reduce the thickness of the housing A1711 in the x direction (left-right direction as viewed from the user when the spatial floating image display device 1000 is in use).

[0231] The thickness of the housing A1711 in the x-direction affects the maximum width (in the x-direction) of the levitating video display device 1000 in its folded state. Therefore, by arranging circuits and circuit boards other than the display device 1 in the housing A1711 on the back side of the frame portion 1733, as shown in Figure 14F(1), the maximum volume of the levitating video display device 1000 in its folded state can be reduced, making it easier to carry and store the device in its folded state.

[0232] In the example of Figure 14F(2), as explained in Figure 14E(2), the placement of the image display surface 1708 of the display device 1 in the housing A1711 is offset vertically (upward) from the center of the orthogonal projection 1709 of the retroreflective plate 2. That is, the center of the image display surface 1708 of the display device 1 is offset upward (upward) from the center of the orthogonal projection 1709 of the retroreflective plate 2. Accordingly, in the example of Figure 14F(2), the backlight drive board 1761 is placed adjacent to the bottom of the display device 1, rather than above it. In the example of Figure 14F(2), the placement of the display device 1 and the backlight drive board 1761 differs from the example of Figure 14F(1), but the other configurations and placements are the same as in the example of Figure 14F(1), so repeated explanations are omitted.

[0233] As explained above, the configuration shown in Figure 14F allows for the creation of a thinner and more suitable housing, enabling the realization of a spatially floating image display device that is more convenient for carrying and storing in a folded state.

[0234] Next, using Figure 14G, we will explain the advantages of offsetting the center position of the image display surface 1708 in the z direction (upward in the vertical direction when the spatially floating image display device 1000 is in use) relative to the center position of the retroreflective plate, as shown in Figures 14E(2) and 14F(2).

[0235] Figure 14G is a view of the floating image display device 1000 in use, viewed from the x-direction (left-right direction from the user's perspective). For example, in the example shown in Figure 14G, the floating image display device 1000 is installed and used on a desk 2000. In Figure 14G, the position of the retroreflective plate 2 on the floating image display device 1000 is indicated by a dotted line. In addition, the image display surface 1708A, which corresponds to the image display surface 1708 in Figures 14E(1) and 14F(1), and the image display surface 1708b, which corresponds to the image display surface 1708 in Figures 14E(2) and 14F(2), are shown with some overlap.

[0236] Furthermore, the floating image when the video display surface is at the position of video display surface 1708A is shown as floating image 3a. The floating image when the video display surface is at the position of video display surface 1708b is shown as floating image 3b. In this explanation, for illustrative purposes, the cases where the video display surface is at the position of video display surface 1708A and the cases where the video display surface is at the position of video display surface 1708b are compared and explained. However, please note that this does not describe an example in which the floating image display device 1000 has multiple video display surfaces simultaneously at both the position of video display surface 1708A and the position of video display surface 1708b.

[0237] In the example shown in Figure 14G, the height range Ha is the height range between the height at which the lower end of the image display surface 1708a is located and the height at which the upper end of the image display surface 1708a is located. This height range Ha is the same as the height range between the upper end position of the floating image 3a and the lower end position of the floating image 3a. Note that the height of the center position of the image display surface 1708a is the same as the height of the center position of image 2 of the retroreflective plate.

[0238] In the example shown in Figure 14G, the height range Hb is the height range between the height at which the lower end of the image display surface 1708b is located and the height at which the upper end of the image display surface 1708b is located. This height range Hb is the same as the height range between the upper end position of the floating image 3b and the lower end position of the floating image 3b. Note that the height of the center position of the image display surface 1708b is higher than the center position of the image 2 of the retroreflective plate, and is offset vertically upward (in the z direction) by a predetermined distance from the center position of the image 2 of the retroreflective plate.

[0239] In Figure 14G, five viewpoints (Viewpoint A, Viewpoint B, Viewpoint C, Viewpoint D, Viewpoint E) with different heights are shown for the user's perspective. In the following explanation, a virtual retroreflective image 2' is set on the drawing. The virtual retroreflective image 2' is located at a mirror-symmetric position of the retroreflective plate 2 with respect to the polarization separation member 101B. The virtual retroreflective image 2' is a virtual image of the retroreflective plate 2 as seen from the user's side due to the reflection by the polarization separation member 101B.

[0240] The following explains the height ranges in which each viewpoint exists.

[0241] First, viewpoint A is located above the line (or plane) 1801 passing through the lower end of the retroreflective image 2' and the lower end of the floating image 3b. Next, viewpoint B is located below the line (or plane) 1801 passing through the line (or plane) 1801 passing through the line (or plane) 1802 passing through the lower end of the retroreflective image 2' and the lower end of the floating image 3a. Next, viewpoint C is located below the line (or plane) 1802 passing through the line (or plane) 1802 passing through the line (or plane) 1803 passing through the upper end of the retroreflective image 2' and the upper end of the floating image 3b. Next, viewpoint D is located below the line (or plane) 1803 passing through the upper end position of the retroreflective image 2' and the upper end position of the floating image 3b, and above the line (or plane) 1804 passing through the upper end position of the retroreflective image 2' and the upper end position of the floating image 3a. Next, viewpoint E is located below the line (or plane) 1804 passing through the line (or plane) 1804 passing through the upper end position of the retroreflective image 2' and the upper end position of the floating image 3a.

[0242] The following describes the viewing conditions of the floating images from each perspective.

[0243] First, at viewpoint A, since it is located above the straight line (or plane) 1801, even when viewing the floating image 3b, the image 2' of the retroreflective plate is not visible behind the position corresponding to the lower edge of the floating image 3b. As a result, the light from the lower edge of the image display surface 1708b is vignetted due to the limitations of the retroreflective plate 2's range and cannot be seen from viewpoint A. Similarly, at viewpoint A, since it is located above the straight line (or plane) 1802, even when viewing the floating image 3a, the image 2' of the retroreflective plate is not visible behind the position corresponding to the lower edge of the floating image 3a. As a result, the light from the lower edge of the image display surface 1708A is vignetted due to the limitations of the retroreflective plate 2's range and cannot be seen from viewpoint A.

[0244] Next, at viewpoint B, since it is located below the straight line (or plane) 1801, when viewing the floating image 3b, the image 2' of the retroreflective plate is visible behind the position corresponding to the lower edge of the floating image 3b. As a result, light from the lower edge of the image display surface 1708b is not vignetted by the retroreflective plate 2 and can be viewed from viewpoint B. On the other hand, at viewpoint B, since it is located above the straight line (or plane) 1802, even when viewing the floating image 3A, the image 2' of the retroreflective plate is not visible behind the position corresponding to the lower edge of the floating image 3A. As a result, light from the lower edge of the image display surface 1708A is vignetted due to the limitation of the retroreflective plate 2's range and cannot be viewed from viewpoint A.

[0245] Next, at viewpoint C, since it is located below the straight line (or plane) 1801, when viewing the floating image 3b, the image 2' of the retroreflective plate is visible behind the position corresponding to the lower edge of the floating image 3b. As a result, light from the lower edge of the image display surface 1708b is not vignetted by the retroreflective plate 2 and can be viewed from viewpoint C. Similarly, at viewpoint C, since it is located below the straight line (or plane) 1802, when viewing the floating image 3A, the image 2' of the retroreflective plate is visible behind the position corresponding to the lower edge of the floating image 3A. As a result, light from the lower edge of the image display surface 1708A is not vignetted by the retroreflective plate 2 and can be viewed from viewpoint C. Furthermore, since viewpoint C is located above the straight line (or plane) 1803, when viewing the floating image 3b, the image 2' of the retroreflective plate is visible behind the position corresponding to the upper edge of the floating image 3b. As a result, light from the upper edge of the image display surface 1708b is not vignetted by the retroreflective plate 2 and can be viewed from viewpoint C. Similarly, since viewpoint C is located above the straight line (or plane) 1804, when viewing the floating image 3A, the image 2' of the retroreflective plate is visible behind the position corresponding to the upper edge of the floating image 3A. As a result, light from the upper edge of the image display surface 1708A is not vignetted by the retroreflective plate 2 and can be viewed from viewpoint C.

[0246] Next, at viewpoint D, since it is located above the straight line (or plane) 1804, when viewing the floating image 3A, the image 2' of the retroreflective plate is visible behind the position corresponding to the upper edge of the floating image 3A. As a result, light from the upper edge of the image display surface 1708b does not experience vignetting due to the retroreflective plate 2 and can be seen from viewpoint D. On the other hand, at viewpoint D, since it is located below the straight line (or plane) 1803, even when viewing the floating image 3b, the image 2' of the retroreflective plate is not visible behind the position corresponding to the upper edge of the floating image 3b. As a result, light from the upper edge of the image display surface 1708A experiences vignetting due to the limitations of the retroreflective plate 2's range and cannot be seen from viewpoint D.

[0247] Next, at viewpoint E, since it is located below the straight line (or plane) 1803, even if the floating image 3b is viewed assuming that the desk 2000 does not extend towards the user, the image 2' of the retroreflective plate is not visible behind the position corresponding to the upper edge of the floating image 3b. Consequently, even if the desk 2000 does not extend towards the user, the light from the upper edge of the image display surface 1708b will be vignetted due to the limitations of the retroreflective plate 2's range and will not be visible from viewpoint E. Similarly, at viewpoint E, since it is located below the straight line (or plane) 1804, even if the floating image 3A is viewed assuming that the desk 2000 does not extend towards the user, the image 2' of the retroreflective plate is not visible behind the position corresponding to the upper edge of the floating image 3A. Consequently, the light from the upper edge of the image display surface 1708A will be vignetted due to the limitations of the retroreflective plate 2's range and will not be visible from viewpoint E.

[0248] As described above, in the example of Figure 14G, when the video display surface is at the position of video display surface 1708a and the floating video 3a is displayed, the floating video 3a can be seen from viewpoints C and D without any vignetting at either the top or bottom edge in the vertical direction. However, in this case, from viewpoints A, B, and E, the floating video 3a will be seen with vignetting at either the top or bottom edge in the vertical direction.

[0249] Furthermore, in the example shown in Figure 14G, when the video display surface is at the position of video display surface 1708b and the floating video 3b is displayed, the floating video 3a can be viewed from viewpoints B and C without any vignetting at either the top or bottom edge in the vertical direction. However, in this case, from viewpoints A, D, and E, the floating video 3b will be viewed with vignetting at either the top or bottom edge in the vertical direction.

[0250] Here, as in the example in Figure 14G, when the floating image display device 1000 is installed and used on a desk 2000, the desk is generally positioned lower than the user's viewpoint. Therefore, in Figure 14G, it is likely that it would be more user-friendly to allow the floating image 3B to be viewed from viewpoints B and C without vignetting at both the top and bottom edges, rather than allowing the floating image 3A to be viewed from viewpoints C and D without vignetting at both the top and bottom edges in the vertical direction. Consequently, in the case of the floating image display device 1000 installed and used on a desk 2000 as in Figure 14G, it is preferable that the position of the image display surface be at the position of image display surface 1708b rather than at the position of image display surface 1708a. That is, it is preferable that the center position of the image display surface, such as image display surface 1708b, be offset vertically upward from the center position of the retroreflective plate 2 when in use. Furthermore, this offset arrangement is meaningful even if the floating image display device 1000 is not foldable. In other words, it may also be applied to floating image display devices 1000 of other embodiments that are not foldable.

[0251] Next, using Figure 14H, an example of a modified housing A1714, which is a modified housing A comprising the spatial floating image display device 1000, will be described. Figures 14H(1) and 14H(2) are views from the housing B side in the operating state. Figures 14H(1) and 14H(2) show modified examples corresponding to Figures 14F(1) and 14F(2), respectively, and, similar to Figures 14F(1) and 14F(2), the arrangement positions of each element stored on the back side of the frame portion 1733 are indicated by dotted lines. Also, similar to Figures 14E(1) and 14E(2), the shaded area on the surface of housing A shown in Figures 14H(1) and 14H(2) is the frame portion.

[0252] In Figures 14H(1) and 14H(2), components that are denoted by the same reference numerals as those in Figures 14F(1) and 14F(2) have the same function and configuration as those in Figures 14F(1) and 14F(2), even if there are differences in size or arrangement. For such components, in order to simplify the explanation, repeated explanations will be omitted except for the differences.

[0253] In Figure 14H(2), the display device 1 is positioned offset vertically (z-direction) upward compared to Figure 14H(1), similar to Figures 14F(1) and 14F(2). The effect of this vertical (z-direction) upward offset is explained in Figure 14G.

[0254] Next, in Figures 14H(1) and 14H(2), the backlight driver board 1761 is positioned on the lateral side (y-direction side) of the display device 1, rather than on the vertical side (z-direction side). Depending on the backlight arrangement, positioning the backlight driver board 1761 on the lateral side of the display device 1 may be more efficient.

[0255] Furthermore, in Figures 14H(1) and 14H(2), the upper end of the housing A1714 is provided with an upper flange portion 1771, and the lower end of the housing A1714 is provided with a lower flange portion 1772. The upper flange portion 1771 and the lower flange portion 1772 act as covers that cover the polarizing mirror holder 1750 and the polarizing separation member 101B when the spatial floating image display device 1000 is in a folded state. The effects of providing the upper flange portion 1771 and the lower flange portion 1772 will be described later.

[0256] Next, Figure 14I is a view of the housing A1714 of the floating video display device 1000, as seen from the rear side from the user's perspective when the floating video display device 1000 is in use. On the right side of the housing A1714 are the video display surface 1708 and the frame portion 1733. An upper flange portion 1771 is provided at the upper end of the housing A1714, protruding from the surface of the video display surface 1708 and the frame portion 1733. The upper flange portion 1771 acts as a cover that covers the upper side of the polarizing mirror holder 1750 and the polarizing separation member 101B when the floating video display device 1000 is in a folded state. A lower flange portion 1772 is provided at the lower end of the housing A1714, protruding from the surface of the video display surface 1708 and the frame portion 1733. The lower flange portion 1772 acts as a cover that covers the lower side of the polarizing mirror holder 1750 and the polarizing separation member 101B when the spatial floating image display device 1000 is in a folded state. When the housing A1714 is provided with an upper flange portion 1771, it is preferable that the opening / closing sensor 1741 be provided on the upper flange portion 1771. This is because it is closer to the housing B than the surface where the image display surface 1708 and the frame portion 1733 are located, which improves the accuracy of the opening / closing sensor 1741.

[0257] Furthermore, the rear surface 17141 of the housing A1714 is provided with, for example, a power cable terminal 1780. It is preferable that this terminal be located on the rear surface of the battery 1768 or power supply circuit 1769 housed in the housing A1714.

[0258] Also, in the example of FIG. 14I, on the back surface of the input interface board (input IF board) 1763, a communication interface terminal (communication IF terminal) 1781, a video signal input interface terminal (video signal input IF terminal) 1782, and a removable media interface (removable media IF) insertion port 1783 are provided.

[0259] Here, as described in FIG. 14F, in the foldable space - floating video display device 1000, in order to suppress tipping over, the connection positions of the cables connected to various terminals are preferably at lower positions in the vertical direction. Here, in FIG. 14I, a communication cable such as a LAN cable is connected to the communication interface terminal 1781. A video signal transmission / reception cable such as an HDMI cable, a DisplayPort cable, or a DVI cable is connected to the video signal input interface terminal 1782. On the other hand, a removable media such as a card - type recording medium is inserted into the removable media interface insertion port 1783, but no cable is connected. Therefore, among the terminals provided on the back surface of the input interface board 1763 in FIG. 14I, the video signal input interface terminal 1782 to which a cable is connected is preferably provided at a lower position than the removable media interface insertion port 1783 to which no cable is connected. The communication interface terminal 1781 to which a cable is connected is preferably provided at a lower position than the removable media interface insertion port 1783 to which no cable is connected. Here, the reference for the "lower position" may be the center position of the terminal area of each interface on the back surface of the housing A1714.

[0260] Also, in FIG. 14I, even when a cable is connected to the communication interface terminal 1781, it is preferable that the removable media can be easily inserted into and removed from the removable media interface insertion port 1783. Here, on the back surface of the housing A1714, if the communication interface terminal 1781 is located more outside than the removable media interface insertion port 1783, the cable connected to the communication interface terminal 1781 may interfere with the user's insertion and removal of the removable media. Therefore, on the back surface of the housing A1714, it is preferable that the communication interface terminal 1781 is arranged more inside than the removable media interface insertion port 1783. In other words, on the back surface of the housing A1714, it is preferable that the removable media interface insertion port 1783 is arranged more outside than the communication interface terminal 1781. In terms of the entire device, on the back surface of the spatial floating image display device 1000, it is preferable that the removable media interface insertion port 1783 is arranged at a position farther from the retroreflective plate 2 than the communication interface terminal 1781.

[0261] Arranging the removable media interface slot 1783 and the communication interface terminal 1781 in this manner makes it more user-friendly. Furthermore, if the video signal input interface terminal 1782 is located further outward from the removable media interface slot 1783 on the back of the housing A1714, the cable connected to the video signal input interface terminal 1782 may get in the way when the user inserts or removes removable media. Therefore, it is preferable that the video signal input interface terminal 1782 be located further inward from the removable media interface slot 1783 on the back of the housing A1714. In other words, it is preferable that the removable media interface slot 1783 be located further outward than the video signal input interface terminal 1782 on the back of the housing A1714. Expressed as a whole device, it is preferable that the removable media interface slot 1783 be located further away from the retroreflective plate 2 than the video signal input interface terminal 1782 on the back of the spatial levitation video display device 1000. Arranging the removable media interface slot 1783 and the video signal input interface terminal 1782 in this manner makes it more user-friendly.

[0262] Note that in the other examples in Figure 14, the explanation of the various terminals on the back of the enclosure A is omitted, but in any of these examples, the layout of the various terminals described in Figure 14I should be adopted.

[0263] As described above, the layout of the various terminals on the back of the spatially floating image display device 1000 according to one embodiment of the present invention makes it possible to more effectively suppress the device from tipping over and to improve usability for the user.

[0264] Next, using Figure 14J, we will describe a foldable spatial floating image display device 1000, which is a modified example of Figure 14A. In the description of Figure 14J, we will explain the differences from Figure 14A, and repeating explanations of the same configuration as Figure 14A will be omitted.

[0265] In the spatially floating image display device 1000 shown in Figure 14J, housing A1714, as described in Figures 14H and 14I, is used as housing A. Furthermore, housing B1713, as described in Figure 14D(2), is used as housing B.

[0266] First, as explained in Figure 14D(2), the housing B1713 is provided with a light-shielding plate area LE. This light-shielding plate area LE is an area that was not provided in the housing B1712 of Figure 14A, and in the operating state of the floating spatial image display device 1000, it extends beyond the floating spatial image 3 to the user side. The effect of providing this light-shielding plate area LE will now be explained.

[0267] In Figure 14J(1), arrow 1798 indicates the line of sight when user 230 looks at the part of the polarization separation member 101B closest to user 230 with the eye closest to the polarization separation member 101B, and the line of sight when that line of sight is specularly reflected by the polarization separation member 101B. In Figure 14J(1), a light-shielding plate area LE is provided to block the reflected line of sight, so even when user 230 looks at the part of the polarization separation member 101B closest to user 230, a black space is visible, preventing the viewing of unnecessary space. In contrast, in the spatial floating image display device 1000 of Figure 14A, a light-shielding plate area LE is not provided in the housing B1712, so when user 230 looks at the part of the polarization separation member 101B closest to user 230, an unnecessary space on the left side (negative x-direction side) from user 230's perspective is visible. If the user 230 perceives unnecessary space in the vicinity of the floating image 3 in the left-right direction, it reduces the user's ability to perceive the floating image 3, which is undesirable in terms of the quality of the floating image display device 1000. Therefore, in the floating image display device 1000 of Figure 14J, a light-shielding plate area LE is provided in the housing B1713 to prevent the user 230 from perceiving unnecessary space, thereby further improving the quality of the N-shaped floating image display device. Here, "preventing the user from perceiving unnecessary space" can also be expressed as "blocking unnecessary field of view."

[0268] Furthermore, in the spatially floating image display device 1000 shown in Figure 14J, the housing B1713 is extended further toward the user 230 than the housing B1712 in Figure 14A. This configuration ensures that, in the folded state shown in Figure 14J(2), the front surface of housing A1714 as viewed from the user and the front surface of housing B1713 as viewed from the user are aligned in the y-direction, forming a continuous surface. Additionally, as explained in Figures 14H and 14I, housing A1714 is provided with an upper flange 1771 at its upper end and a lower flange 1772 at its lower end. In the folded state shown in Figure 14J(2), the upper flange 1771 covers the polarizing mirror holder 1750 and the polarizing separation member 101B from above, and the surface of housing B1713 on the housing side of housing B1713 is in a face-to-face state with the surface of housing A1714 on housing B1713. In the folded state shown in Figure 14J(2), the lower flange portion 1772 covers the polarizing mirror holder 1750 and the polarizing separation member 101B from below, and the surface of the lower flange portion 1772 on the housing B1713 side and the surface of housing B1713 on housing A1714 are in a face-to-face state. In other words, in the folded state shown in Figure 14J(2), the upper flange portion 1771 and the lower flange portion 1772 act as covers that cover the polarizing mirror holder 1750 and the polarizing separation member 101B from above and below, respectively. The protection provided by the upper flange portion 1771 and the lower flange portion 1772 from contact with the outside during transport is a desirable configuration for the polarizing separation member 101B, which is an optical component. Furthermore, the opening / closing sensor 1741 can be configured to detect when the surface of the upper flange portion 1771 on the housing B1713 side and the surface of housing B1713 on housing A1714 are in a face-to-face state, and the control unit 1110 shown in Figure 3 can determine that the floating spatial image display device 1000 is in a folded state.

[0269] Furthermore, in the spatial floating image display device 1000 shown in Figure 14J, the housing B1713 is provided with a rear flange portion 1773. The user-facing side of the rear flange portion 1773 is aligned with the back surface 17141 of the housing A1714 when the device is folded in Figure 14J(2). In the folded state shown in Figure 14J(2), the various terminals provided on the back surface 17141 of the housing A1714 are covered by the rear flange portion 1773 of the housing B1713, protecting them from contact with the outside during transport. Also, in the folded state shown in Figure 14J(2), the right side (positive x-direction) of the housing A1714 as viewed from the user and the right side (positive x-direction) of the rear flange portion 1773 of the housing B1713 as viewed from the user are aligned to form a continuous surface.

[0270] Furthermore, in the example shown in Figure 14J, the heights of the top surfaces of housing A1714 and housing B1713 are aligned, and the heights of the bottom surfaces of housing A1714 and housing B1713 are also aligned. As a result, the spatial floating image display device 1000 forms a roughly rectangular parallelepiped shape when folded as shown in Figure 14J(2), resulting in a simple shape that is easy to handle both for carrying and storage.

[0271] As described above, the floating image display device 1000 shown in Figure 14J of this embodiment can realize a higher quality floating image display device by preventing the user 230 from seeing unnecessary space. Furthermore, the floating image display device 1000 shown in Figure 14J of this embodiment can realize a more suitable configuration in which the polarization separation member 101B, which is an optical component, is covered and protected by the housing when folded. In addition, the floating image display device 1000 shown in Figure 14J of this embodiment forms a roughly rectangular parallelepiped shape when folded, realizing a simple shape that is easy to handle both when carrying and when storing.

[0272] Next, using Figure 14K, we will describe a foldable spatial floating image display device 1000, which is a modified example of Figure 14J. In the description of Figure 14K, we will explain the differences from Figure 14J, and repeating explanations of the same configuration as Figure 14J will be omitted.

[0273] The difference between the floating image display device 1000 in Figure 14K and the floating image display device 1000 in Figure 14J is that in the floating image display device 1000 in Figure 14K, a front flange portion 1774 is provided on the housing A1714, and corresponding to the provision of the front flange portion 1774 on the housing A1714, the extension amount of the housing B1713 on the user 230 side is shortened. With this configuration, in Figure 14K(1), which shows the floating image display device 1000 in use, arrow 1799 indicates the same line of sight of the user 230 as arrow 1798 in Figure 14J(1). In the configuration of Figure 14K(1), the unnecessary field of view that was blocked by the light-shielding plate area LE of the housing B1713 in arrow 1798 in Figure 14J(1) can be blocked by the front flange portion 1774.

[0274] Furthermore, as shown in the enlarged view of Figure 14K(2), the front flange portion 1774 is provided with a front wall 17741 and a side wall 17742. When viewed from the user 230 side, the front flange portion 1774 is closed by the front wall 17741. Also, when viewed from the x-direction side, the front flange portion 1774 is closed by the side wall 17742. In the spatial floating image display device 1000 of Figure 14K, in the folded state of Figure 14K(2), the front flange portion 1774 covers the front of the housing B1713 as viewed from the user 230. Also, in the folded state of Figure 14K(2), the rear side of the side wall 17742 of the front flange portion 1774 as viewed from the user 230 and the front side of the housing B1713 as viewed from the user 230 are aligned. Furthermore, in the spatial levitation image display device 1000 shown in Figure 14K, in the folded state shown in Figure 14K(2), the left side (negative x-direction side) of the side wall 17742 of the front flange portion 1774 as viewed from the user 230 and the left side (negative x-direction side) of the housing B1713 as viewed from the user 230 are aligned to form a continuous surface. Therefore, even in the configuration of the spatial levitation image display device 1000 shown in Figure 14K, the folded state shown in Figure 14K(2) forms a roughly rectangular parallelepiped shape, resulting in a simple shape that is easy to handle for both carrying and storage.

[0275] Furthermore, in the configuration of the spatially floating image display device 1000 shown in Figure 14K, the polarization separation member 101B, which is an optical component, is covered and protected by the housing in the folded state shown in Figure 14K(2).

[0276] As described above, the floating image display device 1000 in Figure 14K of this embodiment can realize a higher quality floating image display device by preventing the user 230 from seeing unnecessary space. Furthermore, the floating image display device 1000 in Figure 14K of this embodiment can realize a more suitable configuration in which the polarization separation member 101B, which is an optical component, is covered and protected by the housing when folded. In addition, the floating image display device 1000 in Figure 14K of this embodiment forms a roughly rectangular parallelepiped shape when folded, realizing a simple shape that is easy to handle both when carrying and when storing.

[0277] Next, using Figure 14L, we will describe a foldable spatial floating image display device 1000, which is a modified example of Figure 14A. In the description of Figure 14L, we will explain the differences from Figure 14A, and repeating explanations of the same configuration as Figure 14A will be omitted.

[0278] In the floating image display device 1000 of Figure 14L, a link mechanism 1753 is used instead of the rotation mechanism 1751 of Figure 14A to vary the relative angle between the polarization separation member 101B and the housing A1715. Here, a link mechanism is a rotation mechanism having two or more rotation axes. In the example of Figure 14L(1), the various distances of the optical path from the display device 1 to the floating image 3 in Figure 14A(1) remain unchanged. However, by using the link mechanism 1753 instead of the rotation mechanism 1751, the polarization separation member 101B can be made smaller than in the configuration of Figure 14A. Also, the housing A can be made smaller than the housing A1711 of Figure 14A, becoming the smaller housing A1715.

[0279] In the folded state of the floating image display device shown in Figure 14A(2), the element that had the greatest influence on the maximum depth (y-direction) of the external dimensions was the depth (y-direction) of the polarization separation member 101B. In contrast, in the example shown in Figure 14L(2), the adoption of the link mechanism 1753 allows the polarization separation member 101B to be configured to have a shorter depth (y-direction). As a result, in Figure 14L(2), the maximum depth (y-direction) of the external dimensions of the floating image display device in the folded state can be made smaller than in Figure 14A(2).

[0280] Furthermore, housing B1716 extends the user-side surface of housing B1712 in Figure 14A toward the user 230, and in the folded state shown in Figure 14L(2), its position in the y-direction approximately coincides with the part of the link mechanism 1753 closest to the user 230. This makes it possible to cover and protect the entire surface of the polarization separation member 101B on the housing B1716 side with housing B1716 in the folded state shown in Figure 14L(2). Housing B1716 also has a rear flange portion 1773. In the folded state shown in Figure 14L(2), the rear surface of housing A1715, as viewed from the user side, is configured to align with the user-side surface of the rear flange portion 1773 of housing B1716. As a result, if various terminals are provided on the back of housing A1715 as viewed from the user's side, these terminals can be covered and protected by the rear flange portion 1773 of housing B1716 in the folded state shown in Figure 14L(2). Furthermore, in the folded state shown in Figure 14L(2), the right side (positive x-direction) of housing A1715 as viewed from the user's side and the right side (positive x-direction) of the rear flange portion 1773 of housing B1716 as viewed from the user's side are aligned to form a continuous surface.

[0281] With the above configuration, in the spatial floating image display device 1000 of FIG. 14L, by adopting the link mechanism 1753, in the usage state of FIG. 14L(1), it is possible to display the same spatial floating image 3 as that of the spatial floating image display device 1000 of FIG. 14A, and in the folded state of FIG. 14L(2), it is possible to make the outer shape smaller than that of the spatial floating image display device 1000 of FIG. 14A. Therefore, according to the spatial floating image display device 1000 of FIG. 14L, by making the maximum volume in the folded state smaller, the device can be carried and stored more suitably.

[0282] In addition, in the housing A1715 of the spatial floating image display device 1000 of FIG. 14L, the configuration of the upper flange portion 1771 and the lower flange portion 1772 of the housing A1714 described in FIGS. 14H, 14I, and 14J may be adopted. By doing so, in the folded state, the polarizing mirror holder 1750 and the polarization separation member 101B can be covered and protected by the housing A.

[0283] Next, with reference to FIG. 14M, a foldable spatial floating image display device 1000, which is a modification of FIG. 14A, will be described. In the description of FIG. 14M, the differences from FIG. 14A will be described, and the repeated description of the same configuration as that of FIG. 14A will be omitted.

[0284] Figure 14M shows an example of a configuration for a foldable floating image display device 1000 that includes an imaging unit 1180 and an aerial operation detection unit 1350. The housing A1717 in Figure 14M extends further toward the user 230 than the housing A1711 in Figure 14A. The front surface of housing A1717 (the side facing the user 230) extends to a position closer to the user 230 than the floating image 3. In the example of Figure 14M, the aerial operation detection unit 1350 is provided in this extended portion of housing A1717. This makes it possible to detect operations by the user 230 on the surface including the floating image 3 when the floating image display device 1000 is in use as shown in Figure 14M(1). The configuration and function of the aerial operation detection unit 1350 are as described in Example 1, so a repeated explanation will be omitted. Furthermore, in the housing A1717 of Figure 14M, the imaging unit 1180 may be provided on the front surface (the side facing the user 230) of the extension portion of housing A1717 that is closer to the user 230 than housing A1711 of Figure 14A. This makes it possible for the imaging unit 1180 to image the user 230 when the spatial levitation video display device 1000 is in use as shown in Figure 14M(1). The control unit 1110 may perform identification processing to determine who the user 230 is based on the image captured by the imaging unit 1180. The imaging unit 1180 may image an area including the user 230 operating the spatial levitation video 3 and the area surrounding the user 230, and the control unit 1110 may perform identification processing to determine whether the user 230 is in front of the spatial levitation video display device 1000 based on the image. The control unit 1110 may also calculate the distance from the user 230 to the spatial levitation video display device 1000 based on the image.

[0285] In this case, if the spatial floating image display device 1000 is equipped with an imaging unit 1180, an aerial operation detection unit 1350, etc., it is preferable to equip it on the housing A1717 side, as shown in Figure 14M, rather than on the housing B1718 side. The reason for this is that, as explained in Figure 14A, it is preferable to configure the housing A side, where the display device 1 which always requires a power supply is housed, to house components that require a power supply and components that require wired signal line connections.

[0286] Furthermore, as shown in Figure 14M, even if the imaging unit 1180 and the air operation detection unit 1350 are provided near the front of the housing A1717, the folding function can be maintained, as shown in the folded state in Figure 14M(2).

[0287] As explained above, the floating video display device 1000 in Figure 14M makes it possible to more favorably incorporate a user aerial operation detection function into a foldable floating video display device. Furthermore, the floating video display device 1000 in Figure 14M makes it possible to incorporate an imaging function capable of capturing images of the user into a foldable floating video display device.

[0288] Figure 14G illustrates that the appearance of the floating image 3 differs at different user viewpoints at different heights, depending on the z-direction position of the image display surface 1708 in the floating image display device 1000. Specifically, it explains that vignetting occurs in the floating image 3 due to limitations in the range of the retroreflective plate 2, depending on the range of the retroreflective plate 2, the position of the image display surface 1708, and the user's viewpoint. Figure 14G illustrates an example where the floating image display device 1000 is installed on a desk 2000. However, the relationship between the height at which the floating image display device 1000 is installed and the user's viewpoint varies depending on the user's environment in which the floating image display device 1000 is used. Therefore, an example of a floating image display device 1000 configured to allow users to more favorably view the floating image 3 in various usage environments will be explained using Figure 14N.

[0289] Figure 14N shows an example of a modified housing A1714, which is a modified housing A comprising the spatial floating image display device 1000. Note that Figure 14N(1) is a view from the housing B side in the operating state. Figure 14N(1) shows a modified example corresponding to Figure 14H(1) or Figure 14H(2). In Figure 14N(1), as with Figures 14H(1) and 14H(2), the arrangement positions of each element stored on the back side of the frame portion 1733 are shown by dotted lines. As with Figures 14H(1) and 14H(2), the surface of housing A in the shaded area is the frame portion 1733. Note that in the explanation of Figure 14N(1), the differences from Figure 14H(1) or Figure 14H(2) will be explained, and the same configuration and similarities as Figure 14H(1) or Figure 14H(2) will not be repeated in the explanation. Here, the frame portion 1733 of the housing A1714 in Figure 14N(1) has a frame portion opening 1733A that is wider vertically than the image display surface 1708. Furthermore, the housing A1714 in Figure 14N(1) has a position variable mechanism 1757 that changes the vertical (z-direction) position of the display device 1 having the image display surface 1708. In the example of Figure 14N, the position variable mechanism 1757 comprises a slider 1758 and a rail guide 1759. In Figure 14N(1), the slider 1758 is located on the back of the display device 1 as viewed from the figure. In Figure 14N(1), it can be seen that the rail guide 1759 is located behind the frame portion opening 1733A.

[0290] Here, the configuration of the display device 1 and the position-adjustable mechanism 1757 in this figure will be explained using Figure 14N(2). Figure 14N(2) is a perspective view of the portion of the housing A1714 that houses the display device 1, the position-adjustable mechanism 1757, and the backlight drive board housing 1761B. The display device 1 includes a liquid crystal display panel 11 having an image display surface 1708, and a light source device 13 on the opposite side of the image display surface 1708. The backlight drive board housing 1761B is provided on the side of the light source device 13. The position-adjustable mechanism 1757 is located on the rear side of the light source device 13 as viewed from the housing B. A slider 1758 is mounted on the rear side of the light source device 13 as viewed from the housing B. In the position-adjustable mechanism 1757, the slider 1758 is vertically adjustable along a vertically extending rail guide 1759. Here, the display device 1, the backlight drive board housing 1761B, and the slider 1758 are fastened together with fastening components such as screws, and their relative positions are fixed. The backlight drive board housing 1761B may be integrated with the display device 1. Therefore, when the slider 1758 is displaced vertically, the display device 1 and the backlight drive board housing 1761B are displaced in accordance with that displacement. In other words, when the slider 1758 is displaced vertically, the image display surface 1708 is displaced in accordance with that displacement. The user adjusts the position of the display device 1 according to the usage state of the floating image display device 1000. The user adjusts the position of the slider 1758 so that the display device 1 is in the desired position, and then fixes the position of the slider 1758 in that position. The method for fixing the position of the slider 1758 in the position variable mechanism 1757 may be locking with fasteners such as screws, or pressing with an elastic body such as a spring. Alternatively, the rail guide 1759 may be provided with periodic grooves, and a position fixing member that fixes the relative position of the slider 1758 and the rail guide 1759 may be fitted into the grooves of the rail guide 1759 to fix the position of the slider 1758. Alternatively, the relative position of the slider 1758 and the housing A1714 may be fixed using a position fixing member that fixes the relative position of the slider 1758 and the housing A1714.In any case, the method for fixing the vertical position of slider 1758 may be to apply various existing techniques for fixing the position of slider mechanisms.

[0291] As described above, the backlight drive board housing 1761B is displaced vertically by the position variable mechanism 1757. Therefore, the control lines and power lines connecting the backlight drive board 1761 to other boards, the battery 1768, or the power supply circuit 1769 should be flexible and adaptable to the displacement of the backlight drive board housing 1761B.

[0292] Figure 14O shows the adjustment of the vertical position of the image display surface 1708 in the housing A1714 of the spatially floating image display device 1000, which has the position variable mechanism 1757 of Figure 14N. In the explanation of Figure 14O, the differences from Figure 14N will be explained, and the same configuration and similarities as in Figure 14N will not be repeated.

[0293] Figure 14O(1) shows the state in which the image display surface 1708 is fixed near the lower end of the vertically extending frame opening 1733A. The display device 1 having the image display surface 1708 can adjust its position vertically from this position using the position adjustment mechanism 1757 as shown by the arrow in the figure. At this time, the backlight drive board 1761 housed inside the frame 1733 also changes position in conjunction with it as shown by the arrow in the figure.

[0294] Furthermore, Figure 14O(2) shows the state in which the image display surface 1708 is fixed near the upper end of the vertically extending frame opening 1733A. The display device 1 having the image display surface 1708 can adjust its position vertically from this position using the position adjustment mechanism 1757 as shown by the arrow in the figure. At this time, the backlight drive board 1761 housed inside the frame 1733 also changes position in conjunction with it as shown by the arrow in the figure.

[0295] The adjustment of the position of the image display surface 1708 in the floating image display device 1000 having a position variable mechanism 1757 has been explained above using Figures 14N and 14O. In the floating image display device 1000 shown in these figures, the user can adjust the position of the image display surface 1708 using the position variable mechanism 1757 according to the usage situation. As a result, the occurrence of vignetting of the floating image 3 caused by the relationship between the range of the retroreflective plate 2, the position of the image display surface 1708, and the position of the user's viewpoint, as explained in Figure 14G, can be reduced at the user's desired viewpoint. In other words, according to the floating image display device 1000 in Figures 14N and 14O, the floating image 3 can be viewed more favorably at the user's desired viewpoint.

[0296] In the technology according to this embodiment, high-resolution and high-brightness video information is displayed in a state of floating in space, enabling users to operate the system without feeling anxious about contact transmission of infectious diseases. By using the technology according to this embodiment in a system used by an unspecified number of users, it becomes possible to reduce the risk of contact transmission of infectious diseases and provide a contactless user interface that can be used without anxiety. This contributes to the United Nations' Sustainable Development Goal (SDG) 3, "Good Health and Well-being."

[0297] Furthermore, the technology according to this embodiment reduces the divergence angle of the emitted image light and aligns it to a specific polarization, thereby efficiently reflecting only the normally reflected light off the retroreflector. This results in high light utilization efficiency and enables the acquisition of bright, clear floating images in space. According to the technology according to this embodiment, it is possible to provide a highly usable non-contact user interface that can significantly reduce power consumption. This contributes to the United Nations' Sustainable Development Goals (SDGs) "9. Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation" and "11. Make cities and human settlements inclusive, safe, and resilient and sustainable."

[0298] Although various embodiments have been described in detail above, the present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are detailed explanations of the entire system in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace 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. [Explanation of symbols]

[0299] 1...Display device, 2...Retroreflective plate (retroreflective plate), 3...Spatial image (floating image in space), 105...Wind glass, 100...Transparent material, 101...Polarization separation material, 101B...Polarization separation material, 12...Absorbing polarizer, 13...Light source device, 54...Optical direction conversion panel, 151...Retroreflective plate, 102, 202...LED substrate, 203...Light guide, 205, 271...Reflective sheet, 206, 270...Phase difference plate, 230...User, 1000...Floating image display device, 1110...Control unit, 1160...Image control unit, 1180...Imaging unit, 1102...Image display unit, 1350...Air operation detection unit, 1351...Air operation detection sensor.

Claims

1. An aerial levitation image display device that displays a real image of a levitating object, A video display unit that displays images, A first housing that holds the aforementioned video display unit, Polarizing mirror and A polarizing mirror holder that holds the aforementioned polarizing mirror, Retroreflective plate and A second housing that holds the retroreflective plate, A first variable mechanism for varying the relative angle between the first housing and the polarizing mirror holder, A second variable mechanism for varying the relative angle between the second housing and the polarizing mirror holder, Equipped with, The first housing and the polarizing mirror holder are connected via the first variable mechanism, and the rotation axis of the first variable mechanism is contained within the first housing when the first housing is viewed from the direction of the rotation axis of the first variable mechanism. The second housing and the polarizing mirror holder are connected via the second variable mechanism, and the rotation axis of the second variable mechanism is contained within the second housing when the second housing is viewed from the direction of the rotation axis of the second variable mechanism. Aerial levitation display device.

2. In the aerial floating image display device according to claim 1, The aerial levitation image display device is configured to be transformable from a state in use to a folded state, by varying the relative angle between the first housing and the polarizing mirror holder using the first variable mechanism, and by varying the relative angle between the second housing and the polarizing mirror holder using the second variable mechanism. Aerial levitation display device.

3. In the aerial floating image display device according to claim 2, Regarding the maximum volume calculated by multiplying the maximum width, maximum depth, and maximum height of the aerial levitation video display device, the maximum volume of the aerial levitation video display device in its folded state is smaller than the maximum volume of the aerial levitation video display device in its operating state. Aerial levitation display device.

4. In the aerial floating image display device according to claim 2, The first housing is equipped with a sensor that detects whether the aerial levitation image display device is in the operating state or the folded state. Aerial levitation display device.

5. In the aerial floating image display device according to claim 1, In the operating state of the aerial floating image display device, the first variable mechanism is configured to be positioned closer to the user viewing the aerial floating image than the second variable mechanism. Aerial levitation display device.

6. In the aerial floating image display device according to claim 1, In the operating state of the aerial levitation image display device, the image display unit held in the first housing and the retroreflective plate held in the second housing are arranged to face each other. Aerial levitation display device.

7. In the aerial floating image display device according to claim 6, In the operating state of the aerial levitation image display device, the center position of the image display screen of the image display unit held in the first housing is offset vertically upward from the center position of the orthogonal projection of the retroreflective plate held in the second housing onto the first housing. Aerial levitation display device.

8. In the aerial floating image display device according to claim 1, Circuit boards and sensors requiring power supply are located in the first housing, just like the video display unit, while the second housing does not contain any circuit boards or sensors requiring power supply. Aerial levitation display device.

9. In the aerial floating image display device according to claim 1, Equipped with a power supply circuit, The first housing is configured such that, when the aerial levitation image display device is in use, the power supply circuit is positioned such that its center of gravity is lower in the vertical direction than the center of the first housing. Aerial levitation display device.

10. In the aerial floating image display device according to claim 1, Equipped with a rechargeable battery, The first housing is configured such that, when the aerial levitation image display device is in use, the secondary battery is positioned such that its center of gravity is lower in the vertical direction than the center position of the first housing. Aerial levitation display device.

11. In the aerial floating image display device according to claim 1, The first housing contains an input interface board, and a cable can be connected to the input interface board from the outside, and the position of the cable connection terminal is positioned lower vertically than the center position of the first housing. Aerial levitation display device.

12. In the aerial floating image display device according to claim 2, When the aerial levitation image display device is in use, the user-facing surface of the first housing and the user-facing surface of the second housing are configured to be aligned in the direction toward the user when the aerial levitation image display device is in use, respectively. Aerial levitation display device.

13. In the aerial floating image display device according to claim 2, In the operating state of the aerial levitation image display device, the end of the first housing on the user's side is provided with a front flange portion, which is a flange portion. In the folded state of the aerial levitation image display device, the front flange portion is configured to cover the user-facing side of the second housing when the aerial levitation image display device is in use. Aerial levitation display device.

14. In the aerial floating image display device according to claim 13, The front flange portion is configured such that the side of the second housing facing the levitating image display device in use and the side of the second housing opposite to the first housing facing the levitating image display device in use are aligned when the levitating image display device is folded. Aerial levitation display device.

15. In the aerial floating image display device according to claim 2, An upper flange portion, which is a flange portion, is provided at the upper end of the first housing. A lower flange portion is provided at the lower end of the first housing, In the folded state of the aerial floating image display device, the upper flange and the lower flange are configured to cover the polarizing mirror. Aerial levitation display device.

16. In the aerial floating image display device according to claim 2, In the second housing, a rear flange portion is provided on the rear side as seen from the user when the aerial levitation image display device is in use. In the folded state of the aerial levitation image display device, the rear flange is configured to cover the back surface of the first housing. Aerial levitation display device.

17. In the aerial floating image display device according to claim 1, A camera for capturing images of the user is provided in the first housing, but not in the second housing. Aerial levitation display device.

18. In the aerial floating image display device according to claim 1, An operation detection sensor for detecting user operations for manipulating the aerial floating image is provided in the first housing, but not in the second housing. Aerial levitation display device.

19. In the aerial floating image display device according to claim 1, The first housing is provided with a position-variable mechanism that allows the position of the video display unit to be changed in the vertical direction during use of the aerial levitation video display device. Aerial levitation display device.

20. In the aerial floating image display device according to claim 19, It includes a slider for changing the position of the video display unit. Aerial levitation display device.

21. In the aerial floating image display device according to claim 1, The second housing has a light-shielding plate area where the retroreflective plate is not located, extending horizontally toward the user from the surface of the retroreflective plate held by the second housing, in order to prevent the user viewing the aerial levitation image display device from viewing unnecessary space through reflection by the polarizing mirror when the aerial levitation image display device is in use. Aerial levitation display device.

22. In the aerial floating image display device according to any one of claims 1 to 21, The first variable mechanism and the second variable mechanism are both rotational mechanisms. Aerial levitation display device.

23. An aerial levitation image display device that displays a real image of a levitating object, A video display unit that displays images, A first housing that holds the aforementioned video display unit, Polarizing mirror and A polarizing mirror holder that holds the aforementioned polarizing mirror, Retroreflective plate and The system comprises a second housing that holds the retroreflective plate, The first housing and the polarizing mirror holder are connected via a first variable mechanism, and the rotation axis of the first variable mechanism is contained within the first housing when the first housing is viewed from the direction of the rotation axis of the first variable mechanism. The second housing and the polarizing mirror holder are connected via a second variable mechanism, and the rotation axis of the second variable mechanism is contained within the second housing when the second housing is viewed from the direction of the rotation axis of the second variable mechanism. In the operating state of the aerial levitation image display device, when the aerial levitation image display device is viewed from the vertical direction, the first housing, the polarizing mirror, and the second housing are arranged to form the letter N. Aerial levitation display device.

24. In the aerial floating image display device according to claim 23, In the operating state of the aerial levitation image display device, the image display unit held in the first housing and the retroreflective plate held in the second housing are arranged to face each other. Aerial levitation display device.

25. In the aerial floating image display device according to claim 24, In the operating state of the aerial levitation image display device, the center position of the image display screen of the image display unit held in the first housing is offset vertically upward from the center position of the orthogonal projection of the retroreflective plate held in the second housing onto the first housing. Aerial levitation display device.

26. In the aerial floating image display device according to claim 23, Circuit boards and sensors requiring power supply are located in the first housing, just like the video display unit, while the second housing does not contain any circuit boards or sensors requiring power supply. Aerial levitation display device.

27. In the aerial floating image display device according to claim 23, Equipped with a power supply circuit, The first housing is configured such that, when the aerial levitation image display device is in use, the power supply circuit is positioned such that its center of gravity is lower in the vertical direction than the center of the first housing. Aerial levitation display device.

28. In the aerial floating image display device according to claim 23, Equipped with a rechargeable battery, The first housing is configured such that, when the aerial levitation image display device is in use, the secondary battery is positioned such that its center of gravity is lower in the vertical direction than the center position of the first housing. Aerial levitation display device.

29. In the aerial floating image display device according to claim 23, The first housing contains an input interface board, and a cable can be connected to the input interface board from the outside, and the position of the cable connection terminal is positioned lower vertically than the center position of the first housing. Aerial levitation display device.

30. In the aerial floating image display device according to claim 23, A camera for capturing images of the user is provided in the first housing, but not in the second housing. Aerial levitation display device.

31. In the aerial floating image display device according to claim 23, An operation detection sensor for detecting user operations for manipulating the aerial floating image is provided in the first housing, but not in the second housing. Aerial levitation display device.

32. In the aerial floating image display device according to claim 23, The first housing is provided with a position-variable mechanism that allows the position of the video display unit to be changed in the vertical direction during use of the aerial levitation video display device. Aerial levitation display device.

33. In the aerial floating image display device according to claim 32, It includes a slider for changing the position of the video display unit. Aerial levitation display device.

34. In the aerial floating image display device according to claim 23, The second housing has a light-shielding plate area where the retroreflective plate is not located, extending horizontally toward the user from the surface of the retroreflective plate held by the second housing, in order to prevent the user viewing the aerial levitation image display device from viewing unnecessary space through reflection by the polarizing mirror when the aerial levitation image display device is in use. Aerial levitation display device.

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