Aerial floating image display device and aerial floating image display system

Abstract

To provide a more suitable aerial floating image display device which, according to the present invention, contributes to Sustainable Development Goals: 3, "Ensure healthy lives and promote well-being for all at all ages," 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."SOLUTION: The aerial floating image display device comprises: a video processing unit; a display unit for displaying the video having undergone video processing by the video processing unit; and an optical system for generating an aerial floating video on the basis of the video displayed by the display unit. At least part of the aerial floating video is formed in a liquid stored in a liquid storage tank.SELECTED DRAWING: Figure 18A

Description

[Technical field]

[0001] The present invention relates to a space floating image display device and a space floating image display system. [Background technology]

[0002] The technology for displaying floating information in space is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-128722 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the disclosure of Patent Document 1 does not sufficiently consider a configuration for obtaining practical brightness and quality of the floating image in space, or a configuration for allowing a user to view the floating image in space more enjoyably.

[0005] An object of the present invention is to provide a more suitable space floating image display device. [Means for solving the problem]

[0006] In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above problems, but to give one example, a space floating image display device includes an image processing unit, a display unit that displays an image processed by the image processing unit, and an optical system that generates a space floating image based on the image displayed by the display unit, and at least a part of the space floating image is formed in a liquid stored in a liquid storage tank. Effect of the Invention

[0007] According to the present invention, a more suitable space floating image display device can be realized. Other objects, configurations and effects will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image display device according to an embodiment of the present invention; [Figure 2A] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2B] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2C] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2D] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a floating-in-the-air image display device according to an embodiment of the present invention; [Figure 2E] 1 is a projection diagram of a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention; [Figure 2F] FIG. 2 is a top view of a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 2G] FIG. 2 is a perspective view showing a corner reflector constituting a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 2H] FIG. 2 is a top view showing a corner reflector constituting a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 2I] 1 is a side view showing a corner reflector constituting a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention; FIG. [Diagram 3] 1 is a diagram showing a configuration example of a space floating image display device according to an embodiment of the present invention; [Figure 4A] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4B] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4C] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4D] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4E] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4F] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4G] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4H] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4I] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4J] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4K] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4L] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4M] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4N] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4O] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Diagram 5] FIG. 2 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 6] FIG. 2 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 7]FIG. 2 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] 1 is a layout diagram showing a main part of a space floating image display device according to an embodiment of the present invention; [Figure 9] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 11] 1 is an explanatory diagram for explaining a light source diffusion characteristic of an image display device according to an embodiment of the present invention. [Figure 12] 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device according to an embodiment of the present invention; [Figure 13A] 1 is a diagram illustrating an example of a problem to be solved by image processing according to an embodiment of the present invention; [Figure 13B] FIG. 4 is an explanatory diagram of an example of image processing according to an embodiment of the present invention. [Figure 13C] FIG. 4 is an explanatory diagram of an example of a video display process according to an embodiment of the present invention. [Figure 13D] FIG. 4 is an explanatory diagram of an example of a video display process according to an embodiment of the present invention. [Figure 14] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 15] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 16] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 17] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 18A] FIG. 1 is a diagram showing an example of a configuration of a space floating image display device according to an embodiment of the present invention. [Figure 18B] FIG. 13 is a diagram showing an example of a state in which a spatial floating image is displayed inside an aquarium. [Figure 19] 1 is a diagram showing an example of a space floating image display system according to an embodiment of the present invention; [Figure 20] 5 is a flowchart showing an example of an operation of the space floating image display device according to an embodiment of the present invention. [Figure 21] FIG. 11 is a diagram illustrating examples of judgment items and judgment conditions. [Figure 22] FIG. 11 is a diagram illustrating an example of settings in a second mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the description of the embodiments, and various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed in this specification. In addition, in all the drawings for explaining the present invention, the same reference numerals are given to parts having the same functions, and repeated explanations thereof may be omitted.

[0010] The following embodiment relates to an image display device capable of transmitting an image produced by image light from an image emission source through a transparent member that divides a space, such as glass, and displaying the image as a floating image outside the transparent member. In the following description of the embodiment, an image floating in space is expressed by the term "floating image in space". Instead of this term, it is also acceptable to express it as "aerial image", "spatial image", "floating image in space", "floating optical image of a displayed image", "floating optical image of a displayed image", etc. The term "floating image in space" that is mainly used in the description of the embodiment is used as a representative example of these terms.

[0011] According to the following embodiment, for example, a suitable image display device can be realized for bank ATMs, station ticket vending machines, digital signage, etc. For example, currently, touch panels are usually used in bank ATMs, station ticket vending machines, etc., but by using a transparent glass surface or a light-transmitting plate material, high-resolution image information can be displayed in a space-floating state on the glass surface or light-transmitting plate material. At this time, by making the divergence angle of the emitted image light small, that is, an acute angle, and further aligning it with a specific polarization, only the normal reflected light is efficiently reflected by the retroreflector, so that the light utilization efficiency is high, and ghost images that occur in addition to the main space-floating image, which was a problem in the conventional retroreflection method, can be suppressed, and a clear space-floating image can be obtained. In addition, a device including the light source of this embodiment can provide a novel and highly usable space-floating image display device (space-floating image display system) that can significantly reduce power consumption. In addition, for example, a space-floating image display device for vehicles that can display a so-called unidirectional space-floating image that can be viewed inside and / or outside the vehicle can be provided. <Example 1>

[0012] <An example of how the space floating image display device can be used> FIG. 1 is a diagram showing an example of a usage form of a space-floating image display device according to an embodiment of the present invention, and is a diagram showing the overall configuration of the space-floating image display device according to this embodiment. The specific configuration of the space-floating image display device will be described in detail using FIG. 2 and the like, but light with a narrow-angle directional characteristic and specific polarization is emitted from the display device (display unit) 1 as an image light beam, and is once incident on the retroreflector 2 after reflection in the optical system in the space-floating image display device, and is retroreflected and transmitted through a transparent member 100 (glass, etc.), forming a real spatial image (space-floating image 3) on the outside of the glass surface. In the following embodiment, the retroreflector 2 (retroreflector) is used as an example of the retroreflector. However, the retroreflector 2 of the present invention is not limited to a flat plate, and is used as an example of a concept including a sheet-like retroreflector attached to a flat or non-flat member, and an entire assembly in which a sheet-like retroreflector is attached to a flat or non-flat member. Furthermore, since the light rays reflected by the retroreflector 2 have the optical property of forming an image, the retroreflector 2 may be expressed as an imaging optical member or an imaging optical plate.

[0013] In addition, in a store or the like, a space is divided by a show window (also called "window glass") 105, which is a light-transmitting member such as glass. According to the space floating image display device of this embodiment, it is possible to transmit the floating image through such a transparent member and display it in one direction to the outside and / or inside of the store (space).

[0014] 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 the window glass 105 with a means for reflecting a specific polarized wave, it is possible to form an aerial image (aerial image) at a desired position inside the store.

[0015] <Example of optical system configuration for space floating image display device> Fig. 2A is a diagram showing an example of the configuration of an optical system of a space-floating image display device according to an embodiment of the present invention. The configuration of the space-floating image display device will be described in more detail with reference to Fig. 2A. As shown in Fig. 2A(1), a display device 1 that diverges specific polarized image light at a narrow angle is provided in the oblique direction of a transparent member 100 such as glass. The display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates specific polarized light having a narrow-angle diffusion characteristic.

[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 into a sheet shape and adhered to the transparent member 100) having a film that selectively reflects the image light of a specific polarization provided on a transparent member 100, and enters the retroreflector 2. A λ / 4 plate 21 is provided on the image light incidence surface of the retroreflector 2. The image light is made to pass through the λ / 4 plate 21 twice, when it enters the retroreflector 2 and when it leaves, and is polarized and converted from the specific polarization to the other polarization. Here, the polarization separation member 101 that selectively reflects the image light of a specific polarization has a property of transmitting the polarized light of the other polarization that has been polarized and converted, so the image light of the specific polarization after polarization conversion passes through the polarization separation member 101. The image light that has passed through the polarization separation member 101 forms a space floating image 3, which is a real image, outside the transparent member 100. 2A shows an example in which the chief ray of the image light incident on the retroreflector 2 is incident at an angle of 90° to the retroreflector 2. However, the incident angle of the chief ray of the image light on the retroreflector 2 is not limited to 90°, and may be, for example, 90°±15°.

[0017] Here, a first example of the polarization design in the optical system of FIG. 2A will be described. For example, the display device 1 may be configured to emit S-polarized image light to the polarization separation member 101, and the polarization separation member 101 may have the property of reflecting S-polarized light and transmitting P-polarized light. In this case, the S-polarized image light that reaches the polarization separation member 101 from the display device 1 is reflected by the polarization separation member 101 and travels toward 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 that the image light is converted from S-polarized light to P-polarized light. The image light converted to P-polarized light travels again toward the polarization separation member 101. Here, the polarization separation member 101 has the property of reflecting S-polarized light and transmitting P-polarized light, so that the P-polarized image light passes through the polarization separation member 101 and then through the transparent member 100. The image light transmitted through the transparent member 100 is generated by the retroreflector 2, and therefore forms a floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 with respect to the polarization separation member 101. This polarization design allows the floating image 3 to be formed appropriately.

[0018] Next, a second example of the polarization design in the optical system of FIG. 2A will be described. For example, the display device 1 may be configured to emit P-polarized image light to the polarization separation member 101, and the polarization separation member 101 may have a property 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 travels toward 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 that the image light is converted from P-polarized light to S-polarized light. The image light converted to S-polarized light travels again toward the polarization separation member 101. Here, the polarization separation member 101 has a property of reflecting P-polarized light and transmitting S-polarized light, so that the S-polarized image light passes through the polarization separation member 101 and then through the transparent member 100. The image light transmitted through the transparent member 100 is generated by the retroreflector 2, and therefore forms a floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 with respect to the polarization separation member 101. This polarization design allows the floating image 3 to be formed appropriately.

[0019] The light that forms the floating image 3 is a collection of light rays that converge from the retroreflector 2 to the optical image of the floating image 3, and these light rays continue to travel straight even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is an image with high directivity, unlike the diffuse image light formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2A, when a user views the floating image 3 in the direction of the arrow A, the floating image 3 is viewed as a bright image. However, when another person views the floating image 3 in the direction of the arrow B, the floating image 3 cannot be viewed as an image at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people facing the user.

[0020] Depending on the performance of the retroreflector 2, the polarization axis of the image light after reflection may become uneven. Also, the reflection angle may become uneven. Such uneven light may not maintain the polarization state and traveling angle assumed in the design. For example, light with such a polarization state and traveling angle that is not assumed in the design may re-enter the image display surface side of the liquid crystal display panel 11 directly from the position of the retroreflector 2 without passing through the polarization separation member. Such light with a polarization state and traveling angle that is not assumed in the design may re-enter the image display surface side of the liquid crystal display panel 11 after being reflected by a component in the space floating image display device. Such light that re-enters the image display surface 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, generating a ghost image and possibly degrading the image quality of the space floating image. Therefore, in this embodiment, an absorbing polarizing plate 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 absorptive polarizing plate 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorptive polarizing plate 12, thereby suppressing the re-reflection. This makes it possible to prevent degradation of image quality due to ghost images of spatially floating images. Specifically, if the display device 1 is configured to emit S-polarized image light to the polarization separation member 101, the absorptive polarizing plate 12 may be a polarizing plate that absorbs P-polarized light. Also, if the display device 1 is configured to emit P-polarized image light to the polarization separation member 101, the absorptive polarizing plate 12 may be a polarizing plate that absorbs S-polarized light.

[0021] The above-mentioned polarization separation member 101 may be formed, for example, of a reflective polarizing plate or a metal multilayer film that reflects a specific polarized wave.

[0022] 2A(2) shows an example of the surface shape of a retroreflector as a representative retroreflector 2. A ray of light incident on the interior of regularly arranged hexagonal prisms is reflected by the walls and bottoms of the hexagonal prisms and emitted as retroreflected light in a direction corresponding to the incident light, and a real floating image is displayed based on the image displayed on the display device 1.

[0023] The resolution of this floating image in space depends not only on the resolution of the liquid crystal display panel 11, but also on the outer shape D and pitch P of the retroreflector 2 shown in Fig. 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 about 80 μm, if the diameter D of the retroreflector is 240 μm and the pitch is 300 μm, one pixel of the floating image in space will be equivalent to 300 μm. For this reason, the effective resolution of the floating image in space will be reduced to about 1 / 3.

[0024] Therefore, in order to make the resolution of the spatial floating image equal to that of the display device 1, it is desirable to make the diameter and pitch of the retroreflective portion close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moire due to the retroreflective plate and the pixels of the liquid crystal display panel, it is preferable to design the pitch ratio of each to be a different integer multiple of one pixel. In addition, it is preferable to arrange the shape so that none of the sides of the retroreflective portion overlaps 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 above example. It may have various surface shapes that realize retroreflection. Specifically, a retroreflection element in which triangular pyramid prisms, hexagonal pyramid prisms, other polygonal prisms, or a combination of these are periodically arranged may be provided on the surface of the retroreflector of this embodiment. Alternatively, a retroreflection element in which these prisms are periodically arranged to form a cube corner may be provided on the surface of the retroreflector of this embodiment. These can also be expressed as a corner reflector array or a multifaceted reflector array. Alternatively, a capsule lens type retroreflection element in which glass beads are periodically arranged may be provided on the surface of the retroreflector of this embodiment. The detailed configuration of these retroreflection elements can be achieved by using existing technology, so a detailed description will be omitted. Specifically, the techniques disclosed in Japanese Patent Application Laid-Open Nos. 2001-33609, 2001-264525, 2005-181555, 2008-70898, and 2009-229942 may be used.

[0026] <Another configuration example 1 of the optical system of the space floating image display device> Another example of the configuration of the optical system of the space floating image display device will be described with reference to Fig. 2B. In Fig. 2B, the components with the same reference numerals as Fig. 2A have the same functions and configurations as Fig. 2A. For such components, repeated explanations will be omitted to simplify the explanation.

[0027] In the optical system of FIG. 2B, as in FIG. 2A, image light of a specific polarization is output from the display device 1. The image light of 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 the image light of a specific polarization. Unlike the polarization separation member 101 of FIG. 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 be expressed as a polarization separation plate. The polarization separation member 101B may be configured as a reflective polarizing plate configured by attaching a polarization separation sheet to a transparent member, for example. Alternatively, the transparent member may be formed of a metal multilayer film that selectively transmits a specific polarization and reflects a polarization of another specific polarization. In FIG. 2B, the polarization separation member 101B is configured to transmit the image light of a specific polarization output from the display device 1.

[0028] The image light transmitted 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 and converted from a specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, when it enters the retroreflector and when it leaves the retroreflector. Here, the polarization separation member 101B has a property of reflecting the polarized light of the other polarization converted by the λ / 4 plate 21, so that 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 and forms a space floating image 3, which is a real image, outside the transparent member 100.

[0029] Here, a first example of the polarization design in the optical system of FIG. 2B will be described. For example, the display device 1 may be configured to emit P-polarized image light to the polarization separation member 101B, and the polarization separation member 101B may have a property 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 travels toward 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 that the image light is converted from P-polarized light to S-polarized light. The image light converted to S-polarized light travels again toward the polarization separation member 101B. Here, the polarization separation member 101B has a property of reflecting S-polarized light and transmitting P-polarized light, so that the S-polarized image light is reflected by the polarization separation member 101 and passes through the transparent member 100. Since the image light transmitted through the transparent member 100 is generated by the retroreflector 2, it forms a space-floating image 3, which is an optical image of the display image of the display device 1, at a position that is in a mirror relationship with the display image of the display device 1 with respect to the polarization separation member 101B. This polarization design allows the space-floating image 3 to be formed appropriately.

[0030] Next, a second example of the polarization design in the optical system of FIG. 2B will be described. For example, the display device 1 may be configured to emit S-polarized image light to the polarization separation member 101B, which may have the property of reflecting P-polarized light and transmitting S-polarized light. In this case, the S-polarized image light reaching the polarization separation member 101B from the display device 1 passes through the polarization separation member 101B and travels toward 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 that the image light is converted from S-polarized light to P-polarized light. The image light converted to P-polarized light travels again toward the polarization separation member 101B. Here, the polarization separation member 101B has the property of reflecting P-polarized light and transmitting S-polarized light, so that the P-polarized image light is reflected by the polarization separation member 101 and passes through the transparent member 100. The image light transmitted through the transparent member 100 is generated by the retroreflector 2, and therefore forms a space-floating image 3, which is an optical image of the display image of the display device 1, at a position that is in a mirror relationship with the display image of the display device 1 with respect to the polarization separation member 101B. With this polarization design, the space-floating image 3 can be formed suitably.

[0031] In FIG. 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 arranged at an angle α (for example, 30°) with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. Then, in the reflection of the polarization separation member 101B, the traveling direction of the image light reflected by the polarization separation member 101B (the direction of the chief ray of the image light) differs from the traveling direction of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light) by an angle β (for example, 60°). By configuring in this way, in the optical system of FIG. 2B, the image light is output at a predetermined angle shown in the figure toward the outside of the transparent member 100, and the space-floating image 3, which is a real image, is formed. In the configuration of FIG. 2B, when the user views the image in the direction of the arrow A, the space-floating image 3 is viewed as a bright image. However, when another person views the image in the direction of the arrow B, the space-floating image 3 cannot be viewed as an image at all. This characteristic is extremely suitable for use in a system that displays images that require high security or highly confidential images that should be concealed from people directly facing the user.

[0032] As described above, the optical system in FIG. 2B is an optical system with a different configuration from the optical system in FIG. 2A, but can form a suitable floating-in-space image in the same way as the optical system in FIG. 2A.

[0033] An absorptive polarizing plate may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. The absorptive polarizing plate may transmit the polarized wave of the image light from the polarization separation member 101B and absorb the polarized wave that is 90° out of phase with the polarized wave of the image light from the polarization separation member 101B. In this way, the image light for forming the space-floating image 3 is sufficiently transmitted, while the external light incident from the space-floating image 3 side of the transparent member 100 can be reduced by about 50%. This makes it possible to reduce stray light in the optical system of FIG. 2B due to the external light incident from the space-floating image 3 side of the transparent member 100.

[0034] <Another configuration example 2 of the optical system of the space floating image display device> Another example of the configuration of the optical system of the space floating image display device will be described with reference to Fig. 2C. In Fig. 2C, the components with the same reference numerals as Fig. 2B have the same functions and configurations as Fig. 2B. For the sake of simplicity, the description of such components will not be repeated.

[0035] The only difference between the optical system in Fig. 2B and the optical system in Fig. 2C is the arrangement 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 Fig. 2B, so repeated explanations will be omitted. The polarization design of the optical system in Fig. 2C is also the same as that of the optical system in Fig. 2B, so repeated explanations will be omitted.

[0036] In the optical system of FIG. 2C, the polarization separation member 101B is arranged at an angle α with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. In FIG. 2C, the angle α is 45°. With this configuration, in the reflection of the polarization separation member 101B, the angle β between the traveling direction of the image light reflected by the polarization separation member 101B (direction of the chief ray of the image light) and the traveling direction of the image light incident from the retroreflector 2 (direction of the chief 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 traveling direction of the image light reflected by the polarization separation member 101B, and the angular relationship of the surfaces constituting the optical system can be simplified. If the surface of the transparent member 100 is arranged so as to be perpendicular to the traveling direction of the image light reflected by the polarization separation member 101B, the angular relationship of the surfaces constituting the optical system can be further simplified. In the configuration of Fig. 2C, when the user looks in the direction of the arrow A, the floating image 3 in space is seen as a bright image. However, when another person looks in the direction of the arrow B, the floating image 3 in space cannot be seen as an image at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be concealed from people directly facing the user.

[0037] As described above, the optical system of Fig. 2C can form a suitable floating image in space similar to the optical system of Fig. 2A and Fig. 2B, even though the optical system of Fig. 2C has a different configuration from the optical system of Fig. 2A and Fig. 2B. In addition, the angles of the surfaces constituting the optical system can be made simpler.

[0038] An absorptive polarizing plate may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. The absorptive polarizing plate may transmit the polarized wave of the image light from the polarization separation member 101B and absorb the polarized wave that is 90° out of phase with the polarized wave of the image light from the polarization separation member 101B. In this way, the image light for forming the space-floating image 3 is sufficiently transmitted, while the external light incident from the space-floating image 3 side of the transparent member 100 can be reduced by about 50%. This makes it possible to reduce stray light in the optical system of FIG. 2C due to the external light incident from the space-floating image 3 side of the transparent member 100.

[0039] <Other Configuration Example 3 of the Optical System of the Space Floating Image Display Device> Another example of the configuration of the optical system of the space floating image display device will be described with reference to FIG. 2D. The optical system of FIG. 2D is an optical system using a retroreflector 5 different from the retroreflector 2 used in FIG. 2A to FIG. 2C. Another example of the configuration 3 of the optical system will be described in more detail below with reference to FIG. 2D to FIG. 2I. In FIG. 2D, components with the same reference numerals as those in FIG. 2A to FIG. 2C have the same functions and configurations. Such components will not be described repeatedly in order to simplify the explanation.

[0040] 2D is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention. A display device 10 that emits image light is provided in an oblique direction of a transparent member 100 such as glass. The display device 10 includes a liquid crystal display panel 11 and a light source device 13 that generates light.

[0041] A chief ray 9020 representing a light beam emitted from the display device 10 travels toward the retroreflector 5 and is incident on the retroreflector 5 at an incident angle α. The incident angle α may be, for example, 45°. However, the incident angle α is not limited to 45°, and may be, for example, 45°±15°.

[0042] The retroreflector 5 is an optical member having an optical property of retroreflecting light rays in at least some directions. In addition, since the reflected light rays have an optical property of forming an image, the retroreflector 5 may be expressed as an imaging optical member or an imaging optical plate.

[0043] 2E, 2F, etc., the principal ray 9020 travels in the z direction and is retroreflected in the x and y directions by the retroreflector 5. As a result, the reflected ray 9021 travels in a direction away from the retroreflector 5 along an optical path mirror-symmetrical to the principal ray 9020 with respect to the retroreflector 5, passes through the transparent member 100, and forms the floating image 3 as a real image on the imaging plane.

[0044] The light beam forming the floating image 3 is a collection of light rays that converge from the retroreflector 5 to the optical image of the floating image 3, and these light rays continue to travel straight even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is an image with high directivity, unlike a diffuse image formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2, when a user views the floating image 3 in the direction of the arrow A, the floating image 3 is viewed as a bright image. However, when another person views the floating image 3 in the direction of the arrow B, the floating image 3 cannot be viewed as an image at all. This characteristic is suitable for use in a system that displays images that require high security or highly confidential images that should be concealed from people facing the user.

[0045] An example of the configuration of the retroreflector 5 will be described with reference to Figs. 2E and 2F. The retroreflector 5 has a configuration in which a plurality of corner reflectors 9040 are arranged in an array on the surface of a transparent member 50. This may be called a corner reflector array or a multi-surface reflector array. The specific configuration of the corner reflector 9040 will be described in detail with reference to Figs. 2G, 2H, and 2I. The light rays 9111, 9112, 9113, and 9114 emitted from the light source 9110 are reflected twice by the two mirror surfaces 9041 and 9042 of the corner reflector 9040, and become reflected light rays 9121, 9122, 9123, and 9124. This double reflection is a retroreflection that turns back in the same direction as the incident direction (travels in a direction rotated by 180°) in the x and y directions, and a regular reflection in which the incident angle and the reflection angle match due to total reflection in the z direction.

[0046] That is, the light rays 9111 to 9114 generate reflected light rays 9121 to 9124 on a straight line symmetrical in the z direction with respect to the corner reflector 9040, and form an aerial real image 9120. The light rays 9111 to 9114 emitted from the light source 9110 are four light rays representative of the diffused light from the light source 9110, and although the light rays incident on the retroreflector 5 are not limited to these depending on the diffusion characteristics of the light source 9110, all the incident light rays cause similar reflections and form an aerial real image 9120. In order to make the drawing easier to see, the position of the light source 9110 and the position of the aerial real image 9120 in the x direction are shown shifted, but in reality the position of the light source 9110 and the position of the aerial real image 9120 in the x direction are the same position, and are overlapped when viewed in the z direction.

[0047] Next, the configuration and effect of the corner reflector 9040 constituting the retroreflector 5 will be described with reference to Figures 2G, 2H, and 2I. The corner reflector 9040 is a rectangular parallelepiped with only two specific faces being mirror faces 9041 and 9042, and the other four faces being made of transparent materials. The retroreflector 5 has a configuration in which the corner reflectors 9040 are arrayed so that the corresponding mirror faces face the same direction.

[0048] When viewed from the top (+z direction), a light ray 9111 emitted from a light source 9110 enters a mirror surface 9041 (or a mirror surface 9042) at a specific angle of incidence, is totally reflected at a reflection point 9130, and then is totally reflected again at a reflection point 9132 on the mirror surface 9042 (or a mirror surface 9041).

[0049] If the angle of incidence of the light ray 9111 with respect to the mirror surface 9041 (or the mirror surface 9042) is θ, the angle of incidence of the first reflected light ray 9131 reflected by the mirror surface 9041 (or the mirror surface 9042) with respect to the mirror surface 9042 (or the mirror surface 9041) can be expressed as 90°-θ. Therefore, with respect to the light ray 9111, the second reflected light ray 9121 is rotated by 2θ by the first reflection and by 2×(90°-θ) by the second reflection, resulting in a total inversion optical path of 180°. On the other hand, when viewed from the side (the direction halfway between -x and -y), total reflection in the z direction occurs only once. Therefore, with respect to the light ray 9111, if the angle of incidence with respect to the mirror surface 9041 or the mirror surface 9042 is φ, the reflected light ray 9121 is rotated by 2×φ by one reflection.

[0050] As a result, the light beam incident on the corner reflector 9040 undergoes retroreflection with an inverted optical path in the x and y directions, and undergoes regular reflection due to total reflection in the z direction. Considering the retroreflector 5, similar reflections occur in each optical path, so that an image is formed at a point symmetrical with respect to the z axis direction due to an inverted optical path that has convergence in the x and y directions.

[0051] 2A to 2C, the retroreflector 2 has retroreflection characteristics in three axial directions. As a result, when an incident light beam with diffusivity is incident on the retroreflector 2, the reflected light beam with convergence travels toward the side of the retroreflector 2 where the light source of the incident light is present. The reflected light beam with convergence forms an image in the air to form a space floating image 3. The traveling direction of the main ray of the reflected light beam with convergence reflected from the retroreflector 2 is the opposite direction to the traveling direction of the main ray of the incident light beam with diffusivity that is incident on the retroreflector 2.

[0052] 2D, the retroreflector 5 has biaxial retroreflection properties and is specular in the other axial direction. As a result, when a diffusive incident light beam is incident on the retroreflector 5, the convergent reflected light beam reflected by the corner reflector array travels toward the side opposite to the side where the light source of the incident light is present with respect to the retroreflector 5. The convergent reflected light beam forms an image in the air to form the space floating image 3.

[0053] The traveling direction of the chief ray of the convergent reflected light beam reflected by the corner reflector array of the retroreflector 5 is not the opposite direction to the traveling direction of the chief ray of the diffusive incident light beam incident on the retroreflector 5. The normal direction component of the plate-shaped surface of the retroreflector 5 in the traveling direction of the chief ray of the diffusive incident light beam incident on the retroreflector 5 and the normal direction component of the plate-shaped surface of the retroreflector 5 in the traveling direction of the chief ray after being reflected by the retroreflector 5 to become a convergent reflected light beam proceed in a straight line without changing before and after reflection by the corner reflector array.

[0054] That is, the diffusive incident light beam is converted into a convergent reflected light beam by reflection on the retroreflector 5, but in the normal direction of the plate-shaped surface of the retroreflector 5, the light beam travels as if passing through the retroreflector 5. Here, the diffusive incident light beam incident on the retroreflector 5 and the convergent reflected light beam emerging from the retroreflector 5 are geometrically symmetrical with respect to the plate-shaped surface of the retroreflector 5.

[0055] The resolution of the space-floating image formed by the light beam from the image output unit 10 depends heavily on the diameter D and pitch P (not shown) of the retroreflector 5 shown in Figures 2E and 2F, in addition to the resolution of the liquid crystal display panel 11. For example, when a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel is used, even if one pixel (one triplet) is about 80 μm, if the diameter D of the retroreflector is 240 μm and the pitch P is 300 μm, one pixel of the space-floating image will be equivalent to 300 μm. For this reason, the effective resolution of the space-floating image is reduced to about 1 / 3.

[0056] Therefore, in order to make the resolution of the spatial floating image equal to that of the display device 10, it is desirable to make the diameter D and pitch P of the retroreflective portion close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moire due to the retroreflective plate and the pixels of the liquid crystal display panel, it is preferable to design the pitch ratio of each to be a different integer multiple of one pixel. In addition, it is preferable to arrange the shape so that none of the sides of the retroreflective portion overlaps with any of the sides of one pixel of the liquid crystal display panel.

[0057] The shape of the retroreflector (imaging optical plate) according to this embodiment is not limited to the above example. It may have various shapes that realize retroreflection. Specifically, it may be various cubic corner bodies, corner reflector arrays, slit mirror arrays, two-sided corner reflector arrays, polyhedral reflector arrays, or shapes in which a combination of their reflective surfaces is periodically arranged. Alternatively, a capsule lens type retroreflection element in which glass beads are periodically arranged may be provided on the surface of the retroreflection plate of this embodiment. Since the detailed configuration of these retroreflection elements can be achieved by using existing technology, detailed description will be omitted. Specifically, it is possible to use the technology disclosed in JP2017-33005A, JP2019-133110A, JP2017-67933A, WO2009 / 131128A, etc.

[0058] 2D, the image light emitted from the display device 10 may be in any polarization state. It does not matter whether it is S-polarized or P-polarized.

[0059] As described above, the optical system of FIG. 2D is an optical system that uses a different retroreflector from the optical systems of FIGS. 2A to 2C, but it can form a more suitable floating-in-space image, similar to the optical system of FIGS. 2A to 2C.

[0060] According to the optical systems of FIGS. 2A, 2B, 2C, and 2D described above, it is possible to provide brighter and higher quality floating images in space.

[0061] <<Block diagram of the internal configuration of the space floating image display device>> Next, a description will be given of a block diagram of the internal configuration of the space-floating image display device 1000. Fig. 3 is a block diagram showing an example of the internal configuration of the space-floating image display device 1000.

[0062] The space floating image display device 1000 includes a retroreflection unit 1101, an image display unit 1102, a light guide 1104, a light source 1105, a power source 1106, an external power source input interface 1111, an operation input unit 1107, a non-volatile memory 1108, a memory 1109, a control unit 1110, an image signal input unit 1131, an audio signal input unit 1133, a communication unit 1132, an air operation detection sensor 1351, an air operation detection unit 1350, an audio output unit 1140, a microphone 1139, an image control unit 1160, a storage unit 1170, an imaging unit 1180, etc. In addition, the space floating image display device 1000 may include a removable media interface 1134, an attitude sensor 1113, a transmissive self-luminous image display device 1650, a second display device 1680, or a secondary battery 1112.

[0063] Each component of the space floating image display device 1000 is disposed in a housing 1190. Note that the imaging unit 1180 and the mid-air operation detection sensor 1351 shown in FIG.

[0064] The retroreflector 1101 in Fig. 3 corresponds to the retroreflector 2 in Fig. 2A, Fig. 2B, and Fig. 2C. The retroreflector 1101 retroreflects light modulated by the image display unit 1102. Of the light reflected from the retroreflector 1101, the light outputted to the outside of the space-floating image display device 1000 forms the space-floating image 3.

[0065] Image display unit 1102 in Fig. 3 corresponds to liquid crystal display panel 11 in Fig. 2A, Fig. 2B, and Fig. 2C. Light source 1105 in Fig. 3 corresponds to light source device 13 in Fig. 2A, Fig. 2B, and Fig. 2C. Image display unit 1102, light guide 1104, and light source 1105 in Fig. 3 correspond to display device 1 in Fig. 2A, Fig. 2B, and Fig. 2C.

[0066] The video display unit 1102 is a display unit that generates a video by modulating transmitted light based on a video signal input under the control of a video control unit 1160 described later. The video display unit 1102 corresponds to the liquid crystal display panel 11 in Figs. 2A, 2B, and 2C. For example, a transmissive liquid crystal panel is used as the video display unit 1102. Alternatively, for example, a reflective liquid crystal panel that modulates reflected light or a DMD (Digital Micromirror Device: registered trademark) panel may be used as the video display unit 1102.

[0067] The light source 1105 generates light for the image display unit 1102 and is a solid-state light source such as an LED light source or a laser light source. The power source 1106 converts an AC current input from the outside via the external power input interface 1111 into a DC current and supplies power to the light source 1105. The power source 1106 also supplies the necessary DC current to each unit in the space-floating image display device 1000. The secondary battery 1112 stores the power supplied from the power source 1106. The secondary battery 1112 also supplies power to the light source 1105 and other components that require power when power is not supplied from the outside via the external power input interface 1111. That is, when the space-floating image display device 1000 includes the secondary battery 1112, the user can use the space-floating image display device 1000 even when power is not supplied from the outside.

[0068] The light guide 1104 guides the light generated by the light source 1105 and irradiates the image display unit 1102. The combination of the light guide 1104 and the light source 1105 can be called a 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 a mirror. There are various types of combination of the light guide 1104 and the light source 1105. Specific configuration examples of the combination of the light guide 1104 and the light source 1105 will be described in detail later.

[0069] The aerial operation detection sensor 1351 is a sensor that detects an operation of the floating-in-space image 3 by a finger of the user 230. The aerial operation detection sensor 1351 senses, for example, a range that overlaps with the entire display range of the floating-in-space image 3. Note that the aerial operation detection sensor 1351 may only sense a range that overlaps with at least a portion of the display range of the floating-in-space image 3.

[0070] Specific examples of the aerial operation detection sensor 1351 include a distance sensor using invisible light such as infrared light, an invisible light laser, ultrasonic waves, etc. The aerial operation detection sensor 1351 may be configured to detect coordinates on a two-dimensional plane by combining a plurality of sensors. The aerial operation detection sensor 1351 may be configured with a ToF (Time of Flight) LiDAR (Light Detection and Ranging) or an image sensor.

[0071] The mid-air operation detection sensor 1351 only needs to be capable of sensing to detect a touch operation or the like performed by a user with a finger on an object displayed as the floating-in-space image 3. Such sensing can be performed using existing technology.

[0072] The aerial operation detection unit 1350 acquires a sensing signal from the aerial operation detection sensor 1351, and performs operations such as determining whether or not the finger of the user 230 has touched an object in the floating in space image 3 and calculating the position (contact position) where the finger of the user 230 has touched the object based on the sensing signal. The aerial operation detection unit 1350 is configured with a circuit such as an FPGA (Field Programmable Gate Array). Some of the functions of the aerial operation detection unit 1350 may be realized by software using a spatial operation detection program executed by the control unit 1110, for example.

[0073] The aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be configured to be built into the space-floating image display device 1000, or may be provided externally separately from the space-floating image display device 1000. When provided separately from the space-floating image 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 space-floating image display device 1000 via a wired or wireless communication connection path or image signal transmission path.

[0074] Also, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be provided separately. This makes it possible to build a system in which the air-floating image display device 1000 without the aerial operation detection function is used as the main body, and only the aerial operation detection function can be added as an option. Also, a configuration in which only the aerial operation detection sensor 1351 is provided separately, and the aerial operation detection unit 1350 is built into the air-floating image display device 1000 may be used. In cases in which it is desired to more freely arrange the aerial operation detection sensor 1351 relative to the installation position of the air-floating image display device 1000, a configuration in which only the aerial operation detection sensor 1351 is provided separately is advantageous.

[0075] The imaging unit 1180 is a camera having an image sensor, and captures the space near the floating-in-space image 3 and / or the face, arms, fingers, etc. of the user 230. A plurality of imaging units 1180 may be provided. By using a plurality of imaging units 1180 or an imaging unit with a depth sensor, the mid-air operation detection unit 1350 can be assisted in the detection process of the touch operation of the floating-in-space image 3 by the user 230. The imaging unit 1180 may be provided separately from the floating-in-space image display device 1000. When the imaging unit 1180 is provided separately from the floating-in-space image display device 1000, it is sufficient to configure it so that an imaging signal can be transmitted to the floating-in-space image display device 1000 via a wired or wireless communication connection path or the like.

[0076] For example, if the aerial operation detection sensor 1351 is configured as an object intrusion sensor that detects whether or not an object has intruded into a plane (intrusion detection plane) including the display surface of the floating image 3, the aerial operation detection sensor 1351 may not be able to detect information such as how far an object (e.g., a user's finger) that has not intruded into the intrusion detection plane is from the intrusion detection plane, or how close the object is to the intrusion detection plane.

[0077] In such a case, the distance between the object and the intrusion detection plane can be calculated by using information such as object depth calculation information based on the captured images of the multiple imaging units 1180 and object depth information by the depth sensor. These pieces of information and various pieces of information such as the distance between the object and the intrusion detection plane are used for various display controls for the floating in space image 3.

[0078] Furthermore, without using the aerial operation detection sensor 1351, the aerial operation detection section 1350 may detect a touch operation on the floating-in-space image 3 by the user 230 based on the captured image by the imaging section 1180.

[0079] Also, the imaging unit 1180 may capture an image of the face of the user 230 operating the floating image 3, and the control unit 1110 may perform an identification process for the user 230. Furthermore, in order to determine whether or not a third person is standing around or behind the user 230 operating the floating image 3 and peeking at the operation of the user 230 on the floating image 3, the imaging unit 1180 may capture an image of a range including the user 230 operating the floating image 3 and the surrounding area of ​​the user 230.

[0080] 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 a signal for an operation different from the air operation (touch operation) by the user 230. In addition to the above-mentioned user 230 who touches the space floating image 3, the operation input unit 1107 may be used, for example, by an administrator to operate the space floating image display device 1000.

[0081] The video signal input unit 1131 is connected to an external video output device and inputs video data. Various digital video input interfaces are possible for the video signal input unit 1131. For example, the video signal input unit 1131 may be configured with a video input interface conforming to the HDMI (registered trademark) (High-Definition Multimedia Interface) standard, a video input interface conforming to the DVI (Digital Visual Interface) standard, or a video input interface conforming to the DisplayPort standard.

[0082] Alternatively, an analog video input interface such as analog RGB or composite video may be provided. The audio signal input unit 1133 inputs audio data by connecting an external audio output device. The audio signal input unit 1133 may be configured with an audio input interface conforming to the HDMI standard, an optical digital terminal interface, a coaxial digital terminal interface, or the like. In the case of an interface conforming to the HDMI standard, the video signal input unit 1131 and the audio signal input unit 1133 may be configured as an interface in which a terminal and a cable are integrated. The audio output unit 1140 is capable of outputting audio based on the audio data input to the audio signal input unit 1133. The audio output unit 1140 may be configured with a speaker.

[0083] 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 a digital signal to an external device, like the Audio Return Channel function defined in the HDMI standard. The microphone 1139 is a microphone that collects sounds around the space floating image display device 1000, converts them into signals, and generates audio signals. The microphone may record a person's voice, such as a user's voice, and the control unit 1110, which will be described later, may perform voice recognition processing on the generated audio signal to obtain text information from the audio signal.

[0084] The non-volatile memory 1108 stores various data used by the space-floating image display device 1000. The data stored in the non-volatile memory 1108 includes, for example, data for various operations to be displayed on the space-floating image 3, display icons, data of objects to be operated by user operations, layout information, etc. The memory 1109 stores image data to be displayed as the space-floating image 3, data for controlling the device, etc.

[0085] The control unit 1110 controls the operation of each unit connected to it. In addition, the control unit 1110 may perform calculation processing based on information obtained from each unit in the space floating image display device 1000 in cooperation with a program stored in the memory 1109.

[0086] The communication unit 1132 communicates with external devices, external servers, and the like via a wired or wireless communication interface. When the communication unit 1132 has a wired communication interface, the wired communication interface may be, for example, an Ethernet LAN interface. When the communication unit 1132 has a wireless communication interface, the communication unit 1132 may be, for example, a Wi-Fi communication interface, a Bluetooth communication interface, or a mobile communication interface such as 4G or 5G. Various data such as video data, image data, and audio data are transmitted and received by communication via the communication unit 1132.

[0087] The removable media interface 1134 is an interface for connecting a removable recording medium (removable media). The removable recording medium (removable media) may be composed of a semiconductor element memory such as a solid state drive (SSD), a magnetic recording medium recording device such as a hard disk drive (HDD), or an optical recording medium such as an optical disk. The removable media interface 1134 is capable of reading out various information such as various data such as video data, image data, and audio data recorded on the removable recording medium. The video data, image data, and the like recorded on the removable recording medium are output as a space floating image 3 via the video display unit 1102 and the retroreflection unit 1101.

[0088] The storage unit 1170 is a storage device that records various information such as various data such as video data, image data, and audio data. The storage unit 1170 may be configured with a magnetic recording medium recording device such as a hard disk drive (HDD) or a semiconductor element memory such as a solid state drive (SSD). For example, various information such as various data such as video data, image data, and audio data may be recorded in advance in the storage unit 1170 at the time of product shipment. In addition, the storage unit 1170 may record various information such as various data such as video data, image data, and audio data acquired from an external device, an external server, etc. via the communication unit 1132.

[0089] The video data, image data, etc. recorded in the storage unit 1170 are output as the space floating image 3 via the video display unit 1102 and the retroreflection unit 1101. The video data, image data, etc. of the display icons and objects for the user to operate, which are displayed as the space floating image 3, are also recorded in the storage unit 1170.

[0090] Layout information of display icons and objects displayed as the space floating image 3, various metadata information related to the objects, and the like are also recorded in the storage unit 1170. The audio data recorded in the storage unit 1170 is output as audio from the audio output unit 1140, for example.

[0091] The video control unit 1160 performs various controls related to the video signal input to the video display unit 1102. The video control unit 1160 may be called a video processing circuit, and may be configured with hardware such as an ASIC, an FPGA, or a video processor. The video control unit 1160 may also be called a video processing unit or an image processing unit. The video control unit 1160 performs control of video switching, such as determining which video signal to input to the video display unit 1102, between the video signal to be stored in the memory 1109 and the video signal (video data) input to the video signal input unit 1131, for example.

[0092] In addition, the image control unit 1160 may generate a superimposed image signal by superimposing the image signal to be stored in memory 1109 and the image signal input from the image signal input unit 1131, and input the superimposed image signal to the image display unit 1102, thereby performing control to form a composite image as a floating-in-space image 3.

[0093] Furthermore, the video control unit 1160 may control image processing of the video signal input from the video signal input unit 1131, the video signal to be stored in the memory 1109, etc. Examples of image processing include scaling processing for enlarging, reducing, transforming, etc. an image, brightness adjustment processing for changing the luminance, contrast adjustment processing for changing the contrast curve of the image, and Retinex processing for decomposing an image into light components and changing the weighting of each component.

[0094] Furthermore, the video control unit 1160 may perform special effect video processing or the like for assisting the aerial operation (touch operation) of the user 230 on the video signal input to the video display unit 1102. The special effect video processing is performed, for example, based on the detection result of the touch operation of the user 230 by the aerial operation detection unit 1350 or the captured image of the user 230 by the imaging unit 1180.

[0095] The attitude sensor 1113 is a sensor composed of a gravity sensor, an acceleration sensor, or a combination of these, and can detect the attitude in which the space-floating image 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 unit. For example, when an undesirable attitude as a user's usage state is detected, the control unit 1110 may perform control to stop displaying the image displayed by the image display unit 1102 and display an error message to the user. Alternatively, when the attitude sensor 1113 detects that the installation attitude of the space-floating image display device 1000 has changed, the control unit 1110 may perform control to rotate the display direction of the image displayed by the image display unit 1102.

[0096] As explained above, various functions are installed in the space-floating image display device 1000. However, the space-floating image display device 1000 does not need to have all of these functions, and can have any configuration as long as it has the function of forming the space-floating image 3.

[0097] <Example of the configuration of a space floating image display device> Next, a configuration example of the space-floating image display device will be described. The layout of the components of the space-floating image display device according to this embodiment can be various depending on the usage form. Each layout of Fig. 4A to Fig. 4M will be described below. In addition, in each example of Fig. 4A to Fig. 4M, the thick line surrounding the space-floating image display device 1000 shows an example of the housing structure of the space-floating image display device 1000.

[0098] FIG. 4A is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4A is equipped with an optical system corresponding to the optical system of FIG. 2A. The space-floating image display device 1000 shown in FIG. 4A is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4A, the space-floating image display device 1000 has a transparent member 100 installed on the upper surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230. Note that the x direction is the left-right direction as seen from the user, the y direction is the front-back direction (depth direction) as seen from the user, and the z direction is the up-down direction (vertical direction). Hereinafter, the definitions of the x-direction, y-direction, and z-direction are the same in each drawing of FIG. 4, so repeated explanation will be omitted.

[0099] FIG. 4B is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4B is equipped with an optical system corresponding to the optical system of FIG. 2A. The space-floating image display device 1000 shown in FIG. 4B is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (the direction of the user 230). That is, in FIG. 4B, the space-floating image display device is installed with the transparent member 100 on the front side of the device (the direction of the user 230). The space-floating image 3 is formed on the user 230 side with respect to the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels in an oblique upward direction. When the midair operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230. 4B, the mid-air operation detection sensor 1351 can use the reflection of sensing light by the user's nail for touch detection by sensing the finger of the user 230 from above. Generally, the nail has a higher reflectivity than the pad of the finger, so that the accuracy of touch detection can be improved by configuring in this way.

[0100] FIG. 4C is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4C is equipped with an optical system corresponding to the optical system of FIG. 2B. The space-floating image display device 1000 shown in FIG. 4C is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4C, the space-floating image display device 1000 has a transparent member 100 installed on the upper surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230.

[0101] FIG. 4D is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4D is equipped with an optical system corresponding to the optical system of FIG. 2B. The space-floating image display device 1000 shown in FIG. 4D is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (the direction of the user 230). That is, in FIG. 4D, the space-floating image display device 1000 is installed with the transparent member 100 on the front side of the device (the direction of the user 230). The space-floating image 3 is formed on the user 230 side with respect to the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels in an oblique upward direction. When the midair operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230. 4D, the mid-air operation detection sensor 1351 can use the reflection of sensing light by the user's nail for touch detection by sensing the finger of the user 230 from above. Generally, the nail has a higher reflectivity than the pad of the finger, so that the accuracy of touch detection can be improved by configuring in this way.

[0102] FIG. 4E is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4E is equipped with an optical system corresponding to the optical system of FIG. 2C. The space-floating image display device 1000 shown in FIG. 4E is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4E, the space-floating image display device 1000 has a transparent member 100 installed on the upper surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels directly upward. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230.

[0103] FIG. 4F is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4F is equipped with an optical system corresponding to the optical system of FIG. 2C. The space-floating image display device 1000 shown in FIG. 4F is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (the direction of the user 230). That is, in FIG. 4F, the space-floating image display device 1000 is installed with the transparent member 100 on the front side of the device (the direction of the user 230). The space-floating image 3 is formed on the user 230 side with respect to the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels toward the user. When the midair operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the finger of the user 230.

[0104] FIG. 4G is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4G is equipped with an optical system corresponding to the optical system of FIG. 2C. In the optical system of the space-floating image display device shown in FIG. 4A to FIG. 4F, the central optical path of the image light emitted from the display device 1 was on the yz plane. That is, in the optical system of the space-floating image display device shown in FIG. 4A to FIG. 4F, the image light traveled in the front-back direction and the up-down direction as seen from the user. In contrast, in the optical system of the space-floating image display device shown in FIG. 4G, the central optical path of the image light emitted from the display device 1 is on the xy plane. That is, in the optical system of the space-floating image display device shown in FIG. 4G, the image light travels in the left-right direction and the front-back direction as seen from the user. In the space-floating image display device 1000 shown in FIG. 4G, the surface on the side on which the space-floating image 3 is formed is installed so as to face the front of the device (the direction of the user 230). That is, in Fig. 4G, the space-floating image display device 1000 has the transparent member 100 installed on the front side of the device (toward the user 230). The space-floating image 3 is formed on the user side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels toward the user. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0105] FIG. 4H is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of FIG. 4H is different from the space-floating image display device of FIG. 4G in that it has a window having a transparent plate 100B such as glass or plastic on the back side of the device (opposite the position where the user 230 views the space-floating image 3, i.e., opposite the traveling direction of the image light of the space-floating image 3 toward the user 230). The other configurations are the same as those of the space-floating image display device of FIG. 4G, so repeated explanations will be omitted. The space-floating image display device 1000 of FIG. 4H has a window having a transparent plate 100B at a position opposite the traveling direction of the image light of the space-floating image 3 with respect to the space-floating image 3. Therefore, when the user 230 views the space-floating image 3, the user 230 can recognize the scenery behind the space-floating image display device 1000 as the background of the space-floating image 3. Therefore, the user 230 can recognize the space floating image 3 as floating in the air in front of the scenery behind the space floating image display device 1000. This can further emphasize the feeling of floating in the air of the space floating image 3.

[0106] Depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separation member 101B, a part of the image 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 visually recognized by the user as stray light. Therefore, in order to prevent this stray light, the transparent plate 100B may not be provided on the window on the back of the space floating image display device 1000.

[0107] Fig. 4I is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 in Fig. 4I is different from the space-floating image display device in Fig. 4H in that a light-shielding door 1410 is provided in the window of the transparent plate 100B arranged on the back of the device (opposite the position where the user 230 views the space-floating image 3). The other configurations are the same as those of the space-floating image display device in Fig. 4H, so repeated explanations will be omitted.

[0108] The opening and closing door 1410 of the space-floating image display device 1000 in FIG. 4I has, for example, a light-shielding plate, and is provided with a mechanism for moving (sliding) the light-shielding plate, a mechanism for rotating the light-shielding plate, or a mechanism for attaching and detaching the light-shielding plate, so that the window (rear window) of the transparent plate 100B located at the back side of the space-floating image display device 1000 can be switched between an open state and a light-shielding state. The movement (sliding) and rotation of the light-shielding plate by the opening and closing door 1410 may be electrically driven by a motor (not shown). The motor may be controlled by the control unit 1110 in FIG. 3. Note that, in the example of FIG. 4I, an example in which the opening and closing door 1410 has two light-shielding plates is disclosed. In contrast, the number of light-shielding plates of the opening and closing door 1410 may be one.

[0109] For example, when the scenery seen through the window of the transparent plate 100B of the space-floating image display device 1000 is outdoors, the brightness of sunlight varies depending on the weather. When the sunlight outdoors is strong, the background of the space-floating image 3 may become too bright, and the user 230 may experience a decrease in visibility of the space-floating image 3. In such a case, if the rear window is put into a light-shielding state by moving (sliding), rotating, or attaching the light-shielding plate of the opening and closing door 1410, the background of the space-floating image 3 becomes dark, and the visibility of the space-floating image 3 can be relatively improved. Such a shielding operation by the light-shielding plate of the opening and closing door 1410 may be directly performed by the force of the hand of the user 230. In response to an operation input via the operation input unit 1107 of FIG. 3, the control unit 1110 may control a motor (not shown) to perform a shielding operation by the light-shielding plate of the opening and closing door 1410.

[0110] In addition, an illuminance sensor may be provided on the rear side (opposite side of the user 230) of the space-floating image display device 1000, 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 FIG. 3 may control a motor (not shown) to perform the opening and closing operation of the light shielding plate of the opening and 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 and closing door 1410 in this way, it is possible to more suitably maintain the visibility of the space-floating image 3 even if the user 230 does not manually open and close the light shielding plate of the opening and closing door 1410.

[0111] Also, the light shielding plate by the opening and closing door 1410 may be manually detachable. Depending on the use purpose and installation environment of the space floating image display device 1000, the user can select whether the rear window is opened or shielded. If the rear window is to be used in a light shielded state for a long period of time, the removable light shielding plate may be fixed in the light shielded state. If the rear window is to be used in an open state for a long period of time, the removable light shielding plate may be removed. The light shielding plate may be attached and detached using a screw, a hook structure, or a fitting structure.

[0112] In the example of the space-floating image display device 1000 in FIG. 4I, depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separation member 101B, a part of the image 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 visually recognized by the user as stray light. Therefore, in order to prevent the stray light, the window on the back of the space-floating image display device 1000 may be configured without providing the transparent plate 100B. The above-mentioned opening and closing door 1410 may be provided on the window that does not have the transparent plate 100B. In order to prevent the stray light, it is desirable that the surface of the light shielding plate of the above-mentioned opening and closing door 1410 on the inside of the housing has a coating or material with low light reflectance.

[0113] Fig. 4J is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 4J is different from the space-floating image display device of Fig. 4H in that an electronically controlled transmittance variable device 1620 is arranged on the rear side window instead of the transparent plate 100B made of glass or plastic. The other configurations are the same as those of the space-floating image display device of Fig. 4H, so repeated explanations will be omitted. An example of the electronically controlled transmittance variable device 1620 is a liquid crystal shutter.

[0114] That is, the liquid crystal shutter can control the transmitted light by controlling the voltage of the liquid crystal element sandwiched between two polarizing plates. Therefore, if the liquid crystal shutter is controlled to increase the transmittance, the scenery through the rear window can be seen through the background of the floating image 3. Also, if the liquid crystal shutter is controlled to increase the transmittance, the scenery through the rear window can be hidden as the background of the floating image 3. In addition, since the liquid crystal shutter can control the intermediate length, it can also be set to a state of transmittance of 50% or the like. For example, the control unit 1110 can control the transmittance of the electronically controlled transmittance variable device 1620 in response to an operation input via the operation input unit 1107 in Fig. 3. With this configuration, in cases where a view through the rear window is desired as the background of the floating image in space 3, but the view through the rear window as the background is too bright and reduces the visibility of the floating image in space 3, it is possible to adjust the transmittance of the electronically controlled transmittance variable device 1620 to adjust the visibility of the floating image in space 3.

[0115] In addition, an illuminance sensor may be provided on the back side (opposite side of the user 230) of the space floating image display device 1000, such as near the back window, to measure the brightness of the space beyond the back window. In this case, the control unit 1110 in Fig. 3 may control the transmittance of the electronically controlled transmittance variable device 1620 according to the detection result of the illuminance sensor. In this way, even if the user 230 does not perform an operation input via the operation input unit 1107 in Fig. 3, the transmittance of the electronically controlled transmittance variable device 1620 can be adjusted according to the brightness of the space beyond the back window, so that the visibility of the space floating image 3 can be more suitably maintained.

[0116] In the above example, a liquid crystal shutter has been described as an example of the electronically controlled transmittance variable device 1620. However, electronic paper may be used as another example of the electronically controlled transmittance variable device 1620. The same effect as described above can be obtained when electronic paper is used. Furthermore, electronic paper consumes very little power to maintain a halftone state. Therefore, a space floating image display device with low power consumption can be realized compared to the case where a liquid crystal shutter is used.

[0117] Fig. 4K is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 4K is different from the space-floating image display device of Fig. 4G in that it has a transmissive self-luminous image display device 1650 instead of the transparent member 100. The other configurations are the same as those of the space-floating image display device of Fig. 4G, so repeated explanations will be omitted.

[0118] In the space-floating image display device 1000 of FIG. 4K, after the image light flux passes through the display surface of the transmissive self-luminous image display device 1650, the space-floating image 3 is formed outside the space-floating image display device 1000. That is, when an image is displayed on the transmissive self-luminous image display device 1650, which is a two-dimensional flat display, the space-floating image 3 can be displayed as a pop-out image further in front of the image of the transmissive self-luminous image display device 1650. At this time, the user 230 can simultaneously view two images at different depth positions. The transmissive self-luminous image display device 1650 may be configured using existing technology such as a transmissive organic EL panel disclosed in, for example, JP 2014-216761 A. Note that the transmissive self-luminous image display device 1650 is not shown in FIG. 3, but may be configured to be connected to other processing units such as the control unit 1110 as one component of the space-floating image display device 1000 of FIG. 3.

[0119] Here, if both the background and an object such as a character are displayed on the transmissive self-luminous image display device 1650, and then only the object such as the character moves to the foreground floating image 3, a more effective surprise video experience can be provided to the user 230.

[0120] Also, if the inside of the space-floating image display device 1000 is kept in a light-shielding state, the background of the transparent self-luminous 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 an image is displayed only on the transparent self-luminous image display device 1650, the transparent self-luminous image display device 1650 appears to the user 230 as a normal two-dimensional flat display, not a transparent display. Note that since the space-floating image 3 in the embodiment of the present invention is displayed as a real optical image in a space without a screen, if the light source of the display device 1 is turned off, the intended display position of the space-floating image 3 becomes an empty space. Therefore, when the transparent self-luminous image display device 1650 is used to display an image as if it were a general two-dimensional flat display, characters, objects, etc. can be suddenly displayed in the air as the space-floating image 3, providing the user 230 with a more effective video experience with a surprise production.

[0121] In addition, the darker the inside of the space-floating image display device 1000, the more the transmissive self-luminous image display device 1650 looks like a two-dimensional flat display. Therefore, an absorptive polarizing plate (not shown) that transmits the polarized wave of the image light reflected by the polarization separation member 101B and absorbs the polarized wave that is 90 degrees out of phase with the polarized wave may be provided on the inner surface of the transmissive self-luminous image display device 1650 (the incident surface of the image light reflected by the polarization separation member 101B to the transmissive self-luminous image display device 1650, i.e., the surface of the transmissive self-luminous image display device 1650 opposite to the space-floating image 3). In this way, the effect on the image light that forms the space-floating image 3 is not so large, but the light that enters the inside of the space-floating image display device 1000 from the outside through the transmissive self-luminous image display device 1650 can be significantly reduced, and the inside of the space-floating image display device 1000 can be made darker, which is preferable.

[0122] FIG. 4L is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of FIG. 4L is a modified example of the space-floating image display device of FIG. 4K. The orientation of the components in the space-floating image display device 1000 is different from that of the space-floating image display device of FIG. 4K, and is closer to the space-floating image display device of FIG. 4F. The functions and operations of each component are the same as those of the space-floating image display device of FIG. 4K, so repeated explanations will be omitted.

[0123] In the space-floating image display device of FIG. 4L as well, after a luminous flux of image light passes through the transmissive self-luminous image display device 1650, a space-floating image 3 is formed on the user 230 side of the transmissive self-luminous image display device 1650.

[0124] In both the example of the space-floating image display device in FIG. 4K and the example of the space-floating image display device in FIG. 4L, the space-floating image 3 is displayed superimposed on the image of the transmissive self-luminous image display device 1650 as seen by the user 230. Here, the position of the space-floating image 3 and the position of the image of the transmissive self-luminous image display device 1650 are configured to have a difference in the depth direction. Therefore, when the user moves his / her head (position of viewpoint), the user can recognize the depth of the two images due to parallax. Therefore, by displaying two images with different depth positions, a three-dimensional image experience can be more suitably provided to the user with the naked eye without the need for stereoscopic glasses or the like.

[0125] Fig. 4M is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 4M is provided with a second display device 1680 on the rear side of the polarization separation member 101B of the space-floating image display device of Fig. 4G as seen from the user. The other configurations are the same as those of the space-floating image display device of Fig. 4G, so repeated explanations will be omitted.

[0126] In the configuration example shown in FIG. 4M, the second display device 1680 is provided behind the display position of the space-floating image 3, and the image display surface faces the space-floating image 3. With this configuration, the image of the second display device 1680 and the space-floating image 3, which are displayed at two different depth positions, can be viewed as overlapping images from the user 230's perspective. In other words, the second display device 1680 is arranged in a direction to display an image toward the user 230 who views the space-floating image 3. Although the second display device 1680 is not shown in FIG. 3, it may be configured to be connected to other processing units such as the control unit 1110 as one component of the space-floating image display device 1000 of FIG. 3.

[0127] The image light of the second display device 1680 of the space floating image display device 1000 of FIG. 4M is visually recognized by the user 230 after passing through the polarization separation member 101B. Therefore, in order for the image light of the second display device 1680 to pass through the polarization separation member 101B more preferably, it is desirable that the image light output from the second display device 1680 is polarized in a vibration direction that the polarization separation member 101B more preferably transmits. That is, it is desirable that the image light is polarized in the same vibration direction as the polarization of the image light output from the display device 1. For example, when the image light output from the display device 1 is S-polarized light, it is desirable that the image light output from the second display device 1680 is also S-polarized light. Furthermore, when the image light output from the display device 1 is P-polarized light, it is desirable that the image light output from the second display device 1680 is also P-polarized light.

[0128] The example of the space-floating image display device of FIG. 4M also has the same effect as the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L in that the second image is displayed behind the space-floating image 3. However, unlike the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L, in the example of the space-floating image display device of FIG. 4M, the luminous flux of the image light for forming the space-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-luminous image display device, and may be a liquid crystal display that is a two-dimensional flat display. The second display device 1680 may be an organic EL display. Therefore, in the example of the space-floating image display device of FIG. 4M, it is possible to realize the space-floating image display device 1000 at a lower cost than the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L.

[0129] Here, depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separation member 101B, a part of the image light output from the display device 1 may be reflected by the polarization separation member 101B and travel toward the second display device 1680. This light (a part of the image light) may be reflected again by the surface of the second display device 1680 and may be visually recognized by the user as stray light.

[0130] Therefore, in order to prevent the stray light, an absorptive polarizing plate may be provided on the surface of the second display device 1680. In this case, the absorptive polarizing plate may be an absorptive polarizing plate that transmits the polarized wave of the image light output from the second display device 1680 and absorbs the polarized wave that is 90° out of phase with the polarized wave of the image light output from the second display device 1680. If the second display device 1680 is a liquid crystal display, an absorptive polarizing plate is also present 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 absorptive polarizing plate on the image output side inside the liquid crystal display, it is not possible to prevent stray light caused by reflection of the cover glass due to light from outside the liquid crystal display. Therefore, it is necessary to separately provide the above-mentioned absorptive polarizing plate on the surface of the cover glass.

[0131] When an image is displayed on the second display device 1680, which is a two-dimensional flat display, the floating-in-space image 3 can be displayed as an image in front of the image on the second display device 1680. In this case, the user 230 can simultaneously view two images with different depth positions. By displaying a character on the floating-in-space image 3 and displaying a background on the second display device 1680, it is possible to provide an effect in which the user 230 is stereoscopically viewing the space in which the character exists.

[0132] Furthermore, if the second display device 1680 displays both the background and an object such as a character, and then the object such as the character moves to the foreground floating image 3, it is possible to provide the user 230 with a more effective surprise video experience.

[0133] Next, Fig. 4N is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 in Fig. 4N is a space-floating image display device that employs the optical system in Fig. 2D. As in the example of the space-floating image display device that employs the optical system in Figs. 2A to 2C, an image is formed in the air as a space-floating image 3 by image light that has passed through a transparent member 100. In addition, the operation of the space-floating image 3 by the user's finger 9004 can be detected using the sensing light of the mid-air operation detection sensor 1351 arranged on the back side of the transparent member 100 as seen from the user.

[0134] In both the example of the space-floating image display device employing the optical system of Figures 2A to 2C and the example of the space-floating image display device employing the optical system of Figure 2D, the space-floating image 3 is imaged in front of the transparent member 100, and the operation of the space-floating image 3 by the user's finger can be detected using the sensing light of the aerial operation detection sensor 1351 arranged on the back side of the transparent member 100 as seen from the user. Therefore, the space-floating image display device employing the optical system of Figure 2D has a different optical system from the space-floating image display device in which the optical system of Figures 2A to 2C is arranged on the back side of the transparent member 100 as seen from the user.

[0135] However, from the user's perspective, the usability of the space-floating image display device employing the optical system of FIG. 2D is almost the same as that of the space-floating image display device employing the optical system of FIGS. 2A to 2C.

[0136] Next, Fig. 4O is a diagram showing an example of the configuration of a space-floating image display device. Fig. 4O is a diagram showing the configuration of the internal optical system in the space-floating image display device 1000 of Fig. 4N. The space-floating image display device 1000 shown in Fig. 4O is equipped with an optical system corresponding to the optical system of Fig. 2D. The space-floating image display device 1000 shown in Fig. 4O is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward.

[0137] That is, in Fig. 4O, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0138] Here, the configuration of Fig. 4O is compared with the configuration of Fig. 4A to confirm the differences. In Fig. 4A, the display device 1 and the space-floating image 3 are in a plane-symmetrical relationship with respect to the plane of the polarization separation member 101. In contrast, in Fig. 4O, the display device 1 and the space-floating image 3 are in a plane-symmetrical relationship with respect to the plane of the retroreflector 5. Also, the configuration of Fig. 4A includes the retroreflector 2 and the λ / 4 plate 21, but these do not exist in Fig. 4O. Also, while it would be more preferable to include the absorbing polarizer 12 in Fig. 4A, the absorbing polarizer 12 is not particularly necessary in Fig. 4O.

[0139] That is, in order to replace the optical system of FIG. 2A in the configuration of FIG. 4A with the optical system of FIG. 2D and replace it with the configuration of FIG. 4O, the following can be done. That is, the polarization separation member 101 in the configuration of FIG. 4A can be replaced with the retroreflector 5, and the retroreflector 2 and the λ / 4 plate 21 can be removed from the configuration of FIG. 4A. The absorptive polarizer 12 can be omitted. If a replacement is made based on this idea, the optical system of FIG. 2A to FIG. 2C mounted on the configuration of the space floating image display device of FIG. 4A to FIG. 4G can be replaced with the optical system of FIG. 2D, and the space floating image display device mounted with the optical system of FIG. 2D can be replaced. At this time, the polarization separation member 101 can be replaced with the retroreflector 5 in FIG. 4A and FIG. 4B, and the polarization separation member 101B can be replaced with the retroreflector 5 in FIG. 4C to FIG. 4G.

[0140] In this way, a space-floating image display device can be realized in which the optical system in the configuration of the space-floating image display device in Figures 4A to 4G is replaced with the optical system in Figure 2D. Even in the space-floating image display device in which the optical system in Figure 2D is replaced, a space-floating image display device with almost the same usability as the space-floating image display device in Figures 4A to 4G can be realized.

[0141] <Display device> Next, the display device 1 of this embodiment will be described with reference to the drawings. The display device 1 of this embodiment includes an image display element (liquid crystal display panel) 11 and a light source device 13 that constitutes the light source thereof. In Fig. 5, the light source device 13 is shown as an exploded perspective view together with the liquid crystal display panel.

[0142] As shown by the arrow 30 in Fig. 5, this liquid crystal display panel (image display element 11) receives an illumination light beam from a light source device 13, which is a backlight device, that has narrow-angle diffusion characteristics, i.e., has strong directivity (straightness) and characteristics similar to laser light with a polarization plane aligned in one direction. The liquid crystal display panel (image display element 11) modulates the received illumination light beam in accordance with an input video signal. The modulated image light is reflected by the retroreflector 2 and passes through a transparent member 100 to form a real image, which is a floating image in space (see Fig. 1).

[0143] In addition, in FIG. 5, the display device 1 is configured to include a liquid crystal display panel 11, a light direction conversion panel 54 that controls the directional characteristics of the light beam emitted from the light source device 13, and a narrow-angle diffusion plate (not shown) as necessary. That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and image light of a specific polarized wave is modulated in intensity by a video signal and emitted (see arrow 30 in FIG. 5). As a result, a desired image is projected as light of a specific polarized wave with high directivity (linearity) through the light direction conversion panel 54 toward the retroreflector 2, and after reflection by the retroreflector 2, it is transmitted toward the eyes of a monitor outside the store (space) to form a space-floating image 3. A protective cover 50 (see FIGS. 6 and 7) may be provided on the surface of the light direction conversion panel 54 described above.

[0144] <Display device example 1> FIG. 6 shows an example of a specific configuration of the display device 1. In FIG. 6, the liquid crystal display panel 11 and the light direction conversion panel 54 are arranged on the light source device 13 of FIG. 5. The light source device 13 is formed, for example, of plastic on the case shown in FIG. 5, and is configured by storing the LED element 201 and the light guide 203 inside. As shown in FIG. 5 and the like, the end face of the light guide 203 has a shape in which the cross-sectional area gradually increases toward the opposite side to the light receiving part in order to convert the divergent light from each LED element 201 into a substantially parallel light beam, and is provided with a lens shape that has an effect of gradually decreasing the divergence angle by multiple total reflections during propagation inside. The liquid crystal display panel 11 constituting the display device 1 is attached to the upper surface of the display device 1. In addition, the LED element 201, which is a semiconductor light source, and the LED board 202 on which its control circuit is mounted are attached to one side (the left end face in this example). A heat sink, which is a member for cooling the heat generated by the LED elements and the control circuit, may be attached to the outer surface of the LED substrate 202.

[0145] In addition, the liquid crystal display panel frame (not shown) attached to the upper surface of the case of the light source device 13 is configured by attaching the liquid crystal display panel 11 attached to the frame, and further by attaching 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 FIG. 3) constituting an 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 contains only specific polarization components, so that a new image display device that is similar to a surface-emitting laser image source driven by an image signal can be obtained. Note that, at present, it is technically and safety impossible to obtain a laser light beam of the same size as the image obtained by the above-mentioned display device 1 using a laser device. Therefore, in this embodiment, light similar to the above-mentioned surface-emitting laser image light is obtained from a light beam from a general light source equipped with an LED element, for example.

[0146] Next, the configuration of the optical system housed in the case of light source device 13 will be described in detail with reference to FIG. 7 together with FIG.

[0147] 6 and 7 are cross-sectional views, and only one of the LED elements 201 constituting the light source is shown, and this is converted into approximately collimated light by the shape of the light-receiving end surface 203a of the light guide 203. For this reason, the light-receiving part of the end surface of the light guide and the LED element are attached while maintaining a predetermined positional relationship.

[0148] Each of the light guides 203 is formed of a light-transmitting resin such as acrylic. The LED light receiving surface at the end of the light guide 203 has a cone-shaped outer circumferential surface obtained by rotating a parabolic cross section, and at the top of the light guide 203, a concave portion having a convex portion (i.e., a convex lens surface) formed in the center is formed, and at the center of the flat portion, a convex lens surface protruding outward (or a concave lens surface recessed inward) is formed (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 forming a cone-shaped outer circumferential surface, and is set within an angle range in which the light emitted from the LED element in the peripheral direction can be totally reflected inside the parabolic shape, or a reflective surface is formed.

[0149] On the other hand, the LED elements 201 are arranged at predetermined positions on the surface of the circuit board, that is, the LED substrate 202. The LED substrate 202 is arranged and fixed such that the LED elements 201 on the surface are positioned in the center of the recessed portion described above with respect to the LED collimator (light-receiving end surface 203a).

[0150] According to this configuration, the shape of light-receiving end surface 203a of light guide 203 makes it possible to extract the light emitted from LED element 201 as substantially parallel light, thereby improving the efficiency of use of the generated light.

[0151] As described above, the light source device 13 is configured by mounting a light source unit in which a plurality of LED elements 201 serving as light sources are arranged on the light receiving end surface 203a serving as a light receiving section provided on the end surface of the light guide 203, and the divergent light beam from the LED elements 201 is converted into substantially parallel light by the lens shape of the light receiving end surface 203a of the light guide end surface, and the light is guided inside the light guide 203 (in a direction parallel to the drawing) as shown by the arrow, and is emitted by the light beam direction conversion means 204 toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front side of the drawing). The uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled by optimizing the distribution (density) of the light beam direction conversion means 204 depending on the shape of the inside or surface of the light guide.

[0152] The light beam direction conversion means 204 described above emits the light beam propagated inside the light guide toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front of the drawing) by changing the shape of the light guide surface or by providing, for example, a portion with a different refractive index inside the light guide. At this time, when the brightness of the screen center and the screen periphery are compared while facing the liquid crystal display panel 11 directly at the center of the screen and placing the viewpoint at the same position as the diagonal dimension of the screen, if the relative brightness ratio is 20% or more, there is no practical problem, and if it exceeds 30%, it is an even better characteristic.

[0153] 6 is a cross-sectional layout diagram for explaining the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including the above-mentioned light guide 203 and LED element 201. In Fig. 6, light source device 13 is composed of light guide 203 formed of, for example, plastic or the like and provided with light beam direction conversion means 204 on its surface or inside, LED element 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc., and on the upper surface thereof is attached liquid crystal display panel 11 equipped with polarizing plates on the light source light entrance surface and image light exit surface.

[0154] A film or sheet-like reflective polarizing plate 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, and selectively reflects one side of the polarized wave (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 reflecting sheet 205 provided on one surface (lower surface in the figure) of the light guide 203, and directed toward the liquid crystal display panel 11. Therefore, a retardation plate (λ / 4 plate) is provided between the reflecting sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the reflected light beam is reflected by the reflecting sheet 205 and passes through twice to convert the reflected light beam from P polarized light to S polarized light, improving the utilization efficiency of the light source light as image light. The image light beam, the light intensity of which is modulated by the image signal in the liquid crystal display panel 11 (arrow 213 in FIG. 6), enters the retroreflector 2. After reflection by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0155] Fig. 7 is a cross-sectional layout diagram for explaining the configuration and action of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED element 201, similar to Fig. 6. Light source device 13 is also similarly composed of light guide 203 formed of, for example, plastic, on the surface or inside of which light flux direction conversion means 204 is provided, LED element 201 as a light source, reflection sheet 205, retardation plate 206, lenticular lens, etc. On the upper surface of light source device 13, liquid crystal display panel 11 having polarizing plates on the light source light entrance surface and the image light exit surface is attached as an image display element.

[0156] A film or sheet-like reflective polarizing plate 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, and selectively reflects one side of the polarized wave (e.g., S wave) 211 of the natural light beam 210 emitted from the LED element 201. That is, in the example of FIG. 7, the selective reflection characteristic of the reflective polarizing plate 49 is different from that of FIG. 7. The reflected light is reflected by the reflective sheet 205 provided on one surface (lower surface in the figure) of the light guide 203, and again heads toward the liquid crystal display panel 11. A retardation 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 polarizing plate 49, and the reflected light beam is reflected by the reflective sheet 205 and passes through it twice, thereby converting the reflected light beam from S polarized light to P polarized light, and improving the utilization efficiency of the light source light as image light. The image light beam intensity-modulated by the image signal in the liquid crystal display panel 11 (arrow 214 in FIG. 7) enters the retroreflector 2. After reflection by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0157] In the light source devices shown in Figures 6 and 7, in addition to the action of the polarizing plate provided on the light incidence surface of the corresponding liquid crystal display panel 11, the polarized component on one side is reflected by the reflective polarizing plate, so that the theoretically obtainable contrast ratio is the reciprocal of the cross transmittance of the reflective polarizing plate multiplied by the reciprocal of the cross transmittance obtained by the two polarizing plates attached to the liquid crystal display panel. This results in high contrast performance. In fact, it was confirmed by experiments that the contrast performance of the displayed image was improved by more than 10 times. As a result, a high-quality image comparable to that of a self-luminous organic EL was obtained.

[0158] <Display device example 2> 8 shows another example of a specific configuration of the display device 1. This light source device 13 is configured by housing an LED, a collimator, a composite diffusion block, a light guide, etc., in a case made of, for example, plastic, and has a liquid crystal display panel 11 attached to its upper surface. Also, an LED element, which is a semiconductor light source, and an LED board mounting a control circuit for the LED element are attached to one side of the case of the light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED element and the control circuit, is attached to the outer surface of the LED board.

[0159] The liquid crystal display panel frame attached to the top surface of the case is configured to have a liquid crystal display panel 11 attached to the frame, and further, an FPC 403 electrically connected to the liquid crystal display panel 11, etc. attached to it. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown here) constituting the electronic device together with the LED elements, which are solid-state light sources.

[0160] <Display device example 3> Next, another example of the specific configuration of the display device 1 (Example 3 of the display device) will be described with reference to Fig. 9. The light source device of this display device 1 converts the divergent light flux of the light (a mixture of P-polarized light and S-polarized light) from the LED into a substantially parallel light flux by the collimator 18, and reflects the light toward the liquid crystal display panel 11 by the reflecting surface of the reflective light guide 304. The reflected light is incident on the reflective polarizing plate 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. The reflective polarizing plate 49 transmits light of a specific polarized wave (e.g., P-polarized light) and causes the transmitted polarized light to be incident on the liquid crystal display panel 11. Here, polarized waves other than the specific polarized wave (e.g., S-polarized light) are reflected by the reflective polarizing plate 49 and head toward the reflective light guide 304 again.

[0161] The reflective polarizing plate 49 is disposed at an angle with respect to the liquid crystal display panel 11 so as not to be perpendicular to the principal ray of the light from the reflecting surface of the reflective light guide 304. The principal ray of the light reflected by the reflective polarizing plate 49 is incident on the transmitting surface of the reflective light guide 304. The light incident on the transmitting surface of the reflective light guide 304 is transmitted through the rear surface of the reflective light guide 304, transmitted through the λ / 4 plate 270 which is a retardation plate, and reflected by the reflecting plate 271. The light reflected by the reflecting plate 271 is transmitted through the λ / 4 plate 270 again, and transmitted through the transmitting surface of the reflective light guide 304. The light transmitted through the transmitting surface of the reflective light guide 304 is incident on the reflective polarizing plate 49 again.

[0162] At this time, the light re-entering the reflective polarizing plate 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarized wave (for example, P-polarized light) that is transmitted through the reflective polarizing plate 49. Therefore, the light whose polarization has been converted is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that, with regard to the polarization design related to the polarization conversion, the polarization may be configured inversely from the above explanation (S-polarized light and P-polarized light may be reversed).

[0163] As a result, the light from the LED is aligned to a specific polarization (e.g., P polarization), enters the liquid crystal display panel 11, and is brightness-modulated according to the video signal to display an image on the panel surface. As in the above example, multiple LEDs that make up the light source are shown (however, because this is a vertical cross section, only one is shown in FIG. 9), and these are attached at predetermined positions relative to the collimator 18.

[0164] The collimators 18 are each formed of, for example, a light-transmitting resin such as acrylic or glass. The collimators 18 may have a cone-shaped outer peripheral surface obtained by rotating a parabolic cross section. The collimators 18 may have a concave portion with a convex portion (i.e., a convex lens surface) formed in the center of the apex (the side facing the LED substrate 102). The collimators 18 have a convex lens surface protruding outward (or a concave lens surface recessed inward) in the center of the flat surface (the side opposite to the apex). The parabolic surface forming the cone-shaped outer peripheral surface of the collimators 18 is set within an angle range that allows the light emitted from the LED in the peripheral direction to be totally reflected therein, or a reflective surface is formed.

[0165] The LEDs are arranged at predetermined positions on the surface of the circuit board, that is, the LED board 102. The LED board 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface are located at the center of the apex of the convex cone shape (or in the concave portion if the apex has a concave portion).

[0166] According to this configuration, among the light emitted from the LED by the collimator 18, the light emitted from the central part is condensed into parallel light by the convex lens surface forming the outer shape of the collimator 18. The light emitted from the other parts toward the periphery is reflected by the parabolic surface forming the outer peripheral surface of the cone shape of the collimator 18, and is condensed into parallel light in the same manner. In other words, according to the collimator 18 having a convex lens in its center and a parabolic surface formed on its periphery, it is possible to extract almost all of the light generated by the LED as parallel light, and it is possible to improve the utilization efficiency of the generated light.

[0167] Furthermore, the light converted into approximately parallel light by the collimator 18 shown in FIG. 9 is reflected by the reflective light guide 304. Of the light, light of a specific polarized wave is transmitted through the reflective polarizing plate 49 by the action of the reflective polarizing plate 49, and light of the other polarized wave reflected by the action of the reflective polarizing plate 49 is transmitted through the reflective light guide 304 again. The light is reflected by the reflector 271 located opposite the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarized and converted by passing twice through the λ / 4 plate 270, which is a retardation plate. The light reflected by the reflector 271 is transmitted through the reflective light guide 304 again and enters the reflective polarizing plate 49 provided on the opposite surface. Since the incident light has been polarized and converted, it is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11 with the same polarization direction. As a result, all the light from the light source can be used, and the geometrical optical utilization efficiency of light is doubled. In addition, since the degree of polarization (extinction ratio) of the reflective polarizer is also included in the extinction ratio of the entire system, the use of the light source device of this embodiment significantly improves the contrast ratio of the entire display device. By adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271, the reflection diffusion angle of light at each reflective surface can be adjusted. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 can be adjusted for each design so that the uniformity of the light incident on the liquid crystal display panel 11 is more suitable.

[0168] It should be noted that the λ / 4 plate 270, which is the retardation plate in Fig. 9, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270. In the configuration of Fig. 9, any retardation plate may be used as long as the phase changes by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the incidence angle distribution of the polarized light.

[0169] <Display device example 4> Furthermore, another example (display example 4) of the configuration of the optical system such as the light source device of the display device will be described with reference to Fig. 10. This is a configuration example in which a diffusion sheet is used instead of the reflective light guide 304 in the light source device of display example 3. 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 not shown in the figure) of the drawing are used on the light emission side of the collimator 18, and the light from the collimator 18 is made to enter between the two optical sheets (diffusion sheets).

[0170] The optical sheet may be one sheet instead of two sheets. In the case of one sheet, the vertical and horizontal diffusion characteristics are adjusted by the fine shape of the front and back surfaces of the single optical sheet. In addition, a plurality of diffusion sheets may be used to share the functions. Here, in the example of FIG. 10, the reflection diffusion characteristics due to the front and back shapes of the optical sheets 207A and 207B may be optimally designed with 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 a plurality of diffusion sheets instead of the light guide.

[0171] In the example of FIG. 10, the polarization conversion is performed in the same manner as in the display device example 3 described above. That is, in the example of FIG. 10, the reflective polarizing plate 49 may be configured to have a property of reflecting S-polarized light (transmitting P-polarized light). In this case, the reflective polarizing plate 49 transmits P-polarized light out of the light emitted from the LED light source, and the transmitted light enters the liquid crystal display panel 11. The reflective polarizing plate 49 reflects S-polarized light out of the light emitted from the LED light source, and the reflected light passes through the retardation plate 270 shown in FIG. 10. The light that passes through the retardation plate 270 is reflected by the reflector 271. The light reflected by the reflector 271 passes through the retardation plate 270 again and is converted to P-polarized light. The polarization-converted light passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11.

[0172] It should be noted that the λ / 4 plate 270, which is the retardation plate in Fig. 10, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light perpendicularly incident on the λ / 4 plate 270. In the configuration of Fig. 10, any retardation plate may be used in which the phase changes by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the distribution of the incident angles of the polarized light. It should be noted that, in Fig. 10 as well, the polarization design related to the polarization conversion may be configured in reverse (reversing the S-polarized light and the P-polarized light) based on the above explanation.

[0173] In a device for general TV use, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown by the X-axis in FIG. 12(a)) and the vertical direction of the screen (shown by the Y-axis in FIG. 12(b)). In contrast, the diffusion characteristics of the light flux emitted from the liquid crystal display panel of this embodiment are 1 / 5 of the 62 degrees of a device for general TV use, when the viewing angle at which the luminance is 50% of that when viewed from the front (angle 0 degrees) is set to 13 degrees, as shown in Example 1 of FIG. 12. Similarly, the vertical viewing angle is optimized by optimizing the reflection angle of the reflective light guide and the area of ​​the reflection surface so that the viewing angle on the upper side is unequal between the top and bottom and is kept to about 1 / 3 of the viewing angle on the lower side. As a result, the amount of image light heading in the monitoring direction is significantly improved compared to conventional liquid crystal TVs, and the luminance is 50 times or more higher.

[0174] Furthermore, assuming the viewing angle characteristics shown in Example 2 in Figure 12, the viewing angle at which the brightness is 50% of that when viewed from the front (angle 0 degrees) is set to 5 degrees, which is 1 / 12 of the 62 degrees of devices used for general TV applications. Similarly, the vertical viewing angle is optimized by optimizing the reflection angle of the reflective light guide and the area of ​​the reflective surface so that the viewing angle is approximately 1 / 12 of that of devices used for general TV applications, with equal viewing angles both above and below. As a result, the amount of image light heading in the monitoring direction is significantly improved compared to conventional LCD TVs, and the brightness is more than 100 times higher.

[0175] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux heading in the monitoring direction can be concentrated, greatly improving the efficiency of light utilization. As a result, even if a liquid crystal display panel for general TV applications is used, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create an image display device that is compatible with information display systems facing bright outdoors.

[0176] When using a large LCD panel, the overall brightness of the screen can be improved by directing the light around the screen inward so that it is directed toward the observer when the observer faces the center of the screen. Figure 11 shows the convergence angle of the long and short sides of the panel when the observer's distance from the panel L and the panel size (screen ratio 16:10) are used as parameters. When monitoring with the screen vertically long, the convergence angle can be set according to the short side. For example, when using a 22-inch panel vertically and the monitoring distance is 0.8 m, a convergence angle of 10 degrees will allow the image light from the four corners of the screen to be effectively directed toward the observer.

[0177] Similarly, when monitoring with a 15-inch panel in portrait orientation and a monitoring distance of 0.8 m, a convergence angle of 7 degrees will allow the image light from the four corners of the screen to be effectively directed toward the observer. As described above, depending on the size of the LCD panel and whether it is used portrait or landscape, the overall brightness of the screen can be improved by directing the image light from the periphery of the screen toward the observer who is in the optimal position to monitor the center of the screen.

[0178] The basic configuration, as shown in FIG. 9, is that a light beam with a narrow-angle directional characteristic is incident on a liquid crystal display panel 11 from a light source device, and the brightness is modulated according to a video signal, so that the video information displayed on the screen of the liquid crystal display panel 11 is reflected by a retroreflector, and the resulting floating-in-space image is displayed indoors or outdoors via a transparent member 100.

[0179] By using the display device and light source device according to one embodiment of the present invention described above, it is possible to realize a space floating image display device with higher light utilization efficiency.

[0180] <Example of image display processing in a space floating image display device> Next, an example of a problem solved by the image processing of this embodiment will be described with reference to Fig. 13A. In the space-floating image display device 1000, when the back side of the space-floating image 3 from the user's perspective is inside the housing of the space-floating image display device 1000 and is sufficiently dark, the user visually recognizes that the background of the space-floating image 3 is black.

[0181] Here, an example of displaying a character "panda" 1525 in the space floating image 3 will be described with reference to Fig. 13A. First, the image control unit 1160 in Fig. 3 distinguishes and recognizes the pixel area in which the image of the character "panda" 1525 is drawn from the transparent information area 1520, which is the background image, for an image including the pixel area in which the image of the character "panda" 1525 is drawn and the transparent information area 1520, which is the background image, as shown in Fig. 13A(1).

[0182] A method for distinguishing and recognizing a character image from a background image may, for example, be configured so that the image processing of the video control unit 1160 can process the background image layer and the layer of a character image in front of the background image layer as separate layers, and the character image and background image can be distinguished and recognized based on the overlay relationship when these layers are combined.

[0183] Here, the image control unit 1160 recognizes the black of the pixel that draws an object such as a character image and the transparent information pixel as different information. However, it is assumed that the brightness of both the black pixel that draws the object and the transparent information pixel is 0. In this case, when the space floating image 3 is displayed, there is no difference in brightness between the pixel that draws black in the image of the character "panda" 1525 and the pixel of the transparent information area 1520 that is the background image. Therefore, in the space floating image 3, as shown in FIG. 13A(2), there is no brightness in either the pixel that draws black in the image of the character "panda" 1525 and the pixel of the transparent information area 1520, and they are visually recognized by the user as the same optical black space. In other words, the part that draws black in the image of the character "panda" 1525 that is an object blends into the background, and only the non-black part of the character "panda" 1525 is recognized as an image floating in the display area of ​​the space floating image 3.

[0184] An example of image processing of this embodiment will be described with reference to FIG. 13B. FIG. 13B is a diagram for explaining an example of image processing that more suitably solves the problem that the black image area of ​​the object blends into the background, as described in FIG. 13A. In FIG. 13B(1) and (2), the upper side shows the display state of the floating in space image 3, and the lower side shows the input / output characteristics of the image processing of the image of the object. Note that the image of the object (character "panda" 1525) and the corresponding data may be read from the storage unit 1170 or memory 1109 in FIG. 3. Alternatively, they may be input from the image signal input unit 1131. Alternatively, they may be acquired via the communication unit 1132.

[0185] Here, in the state of Fig. 13B(1), the input / output characteristics of the image processing of the image of the object are in a linear state with no particular adjustment. In this case, the display state is the same as Fig. 13A(2), and the black image area of ​​the object blends into the background. In contrast, in Fig. 13B(2), the video control unit 1160 of this embodiment adjusts the input / output characteristics of the image processing of the image of the object (character "panda" 1525) to the linear input / output characteristics shown in the lower part.

[0186] That is, the video control unit 1160 performs image processing of input / output characteristics on the image of the object (character "panda" 1525) that has a characteristic of converting the pixels of the input image into output pixels with increased luminance values ​​of pixels in low luminance areas. After the image of the object (character "panda" 1525) is subjected to the image processing of the input / output characteristics, a video including the image of the object (character "panda" 1525) is input to the display device 1 and displayed. Then, as shown in the upper part of FIG. 13B(2), the display state of the floating in space video 3 is such that the luminance of pixel areas that draw black in the image of the character "panda" 1525 increases. As a result, the user can recognize the area that draws black among the areas that draw the image of the character "panda" 1525 as distinct from the black of the background without blending in, and the object can be displayed more suitably.

[0187] That is, by using the image processing of Fig. 13B(2), the area displaying the image of the character "panda" 1525, which is an object, can be distinguished from the black background inside the housing of the space-floating image display device 1000 through the window, improving the visibility of the object. Therefore, for example, even if the pixels constituting the object include pixels with a brightness value of 0 before the image processing (i.e., the time when the image of the object and the corresponding data are read from the storage unit 1170 or memory 1109 in Fig. 3, the time when the image of the object is input from the video signal input unit 1131, or the time when the data of the object is obtained via the communication unit 1132, etc.), the image is converted into an object with a high brightness value of the pixels in the low brightness area by the image processing of the input / output characteristics by the video control unit 1160, and then displayed on the display device 1, and is converted into the space-floating image 3 by the optical system of the space-floating image display device 1000.

[0188] In other words, the pixels that make up the object after image processing of the input / output characteristics are converted to a state in which they do not include pixels with a brightness value of 0, and then the object is displayed on the display device 1 and converted into a floating-in-space image 3 by the optical system of the floating-in-space image display device 1000.

[0189] In the image processing of FIG. 13B(2), a method for applying image processing with the input / output characteristics of FIG. 13B(2) only to the image area of ​​the object (character “panda” 1525) is, for example, to configure the image processing of the video control unit 1160 so that the background image layer and the layer of the character image in front of the background image layer can be processed as separate layers, and the image processing with the input / output characteristics of FIG. 13B(2) is applied to the layer of the character image while not applying the image processing to the background image layer.

[0190] Then, by compositing these layers, image processing with a characteristic of raising the low brightness area of ​​the input image is performed only on the character image, as shown in Fig. 13B(2). Alternatively, after the character image layer and the background image layer are composited, the image processing with the input / output characteristic of Fig. 13B(2) may be performed only on the character image area.

[0191] In addition, the input / output image characteristics used in the image processing for boosting the low luminance region of the input / output characteristics for the input image are not limited to the example of FIG. 13B(2). Any image processing for boosting low luminance may be used, including so-called brightness adjustment. Alternatively, image processing for improving visibility may be performed by controlling the gain that changes the weighting of the Retinex processing, as disclosed in International Publication WO 2014 / 162533.

[0192] According to the image processing of FIG. 13B(2) described above, it is possible to allow the user to recognize areas in which black is drawn among areas in which images of characters, objects, etc. are drawn without blending into the black background, thereby making it possible to realize a more suitable display.

[0193] In the example of Figures 13A and 13B, the problem and more suitable image processing are explained using a space-floating image display device in which the background appears black (for example, the space-floating image display device 1000 in Figures 4A to 4G, or the space-floating image display device 1000 in the state in which the rear window is blocked in Figures 4I and 4J). However, the image processing is also effective in devices other than these space-floating image display devices.

[0194] Specifically, in the space-floating image display device 1000 in Fig. 4H, or in Fig. 4I and Fig. 4J where the rear window is not shaded, the background of the space-floating image 3 is not black, but the view behind the space-floating image display device 1000 through the window. In this case, the problems described in Fig. 13A and Fig. 13B also exist.

[0195] That is, the part of the image of the character "panda" 1525, which is an object, that is drawn in black will blend into the scenery behind the space-floating image display device 1000 through the window. In this case, by using the image processing of Fig. 13B(2), the part of the image of the character "panda" 1525, which is an object, that is drawn in black will be distinguished from the scenery behind the space-floating image display device 1000 through the window, improving the visibility of the object.

[0196] In other words, by using the image processing of FIG. 13B(2), the area displaying the image of the object character “panda” 1525 can be recognized as distinct from the scenery behind the space floating image display device 1000 through the window, and it can be more clearly recognized that the object character “panda” 1525 is in front of the scenery, improving the visibility of the object.

[0197] In addition, in the space-floating image display device 1000 of Figures 4K, 4L, and 4M, as described above, when another image (such as an image of the transmissive self-luminous image display device 1650 or an image of the second display device 1680) is displayed at a position different in depth from the space-floating image 3, the background of the space-floating image 3 is not black, but the other image. In this case, the problem described in Figures 13A and 13B also exists.

[0198] That is, the part of the image of the character "panda" 1525, which is an object, that is drawn in black will blend into the other image that is displayed at a different depth from the floating in space image 3. In this case as well, by using the image processing of Fig. 13B(2), the part of the image of the character "panda" 1525, which is an object, that is drawn in black can be recognized as being distinct from the other image, improving the visibility of the object.

[0199] In other words, by using the image processing of Figure 13B (2), the area displaying the image of the object character "panda" 1525 can be recognized as distinct from the other image, and it can be more easily recognized that the object character "panda" 1525 is in front of the other image, improving the visibility of the object.

[0200] An example of the image display process of this embodiment will be described with reference to Fig. 13C. Fig. 13C shows an example of the image display of this embodiment in which the floating-in-space image 3 and a second image 2050, which is another image, are displayed simultaneously. The second image 2050 may correspond to the display image of the transmissive self-luminous image display device 1650 of Fig. 4K or Fig. 4L. The second image 2050 may also correspond to the display image of the second display device 1680 of Fig. 4M.

[0201] That is, the example of the image display in Fig. 13C shows an example of a specific example of the image display example of the space-floating image display device 1000 in Fig. 4K, Fig. 4L, and Fig. 4M. In the example of this figure, a bear character is displayed in the space-floating image 3. The area other than the bear character in the space-floating image 3 is displayed in black, and becomes transparent as a space-floating image. Also, the second image 2050 is a background image in which a plain, a mountain, and a sun are drawn.

[0202] Here, in Fig. 13C, the floating-in-space image 3 and the second image 2050 are displayed at different depth positions. When the user 230 views the two images, the floating-in-space image 3 and the second image 2050, in the line of sight of the arrow 2040, the user 230 can view the images in a state where the two images are superimposed. Specifically, the bear character of the floating-in-space image 3 appears superimposed in front of the background of the plains, mountains, and sun depicted in the second image 2050.

[0203] Here, since the floating-in-space image 3 is formed as a real image in the air, when the user 230 moves his / her viewpoint slightly, the user 230 can recognize the depth of the floating-in-space image 3 and the second image 2050 due to parallax. Therefore, the user 230 can get a stronger sense of floating in space from the floating-in-space image 3 while viewing the two images in an overlapping state.

[0204] An example of the image display process of this embodiment will be described with reference to Fig. 13D. Fig. 13D(1) is a diagram showing the floating in space image 3 from the image display example of this embodiment of Fig. 13C, viewed in the line of sight of the user 230. Here, a bear character is displayed in the floating in space image 3. The area other than the bear character in the floating in space image 3 is displayed in black, and becomes transparent as a floating in space image.

[0205] Fig. 13D(2) is a diagram showing the second image 2050 in the example of the image display of this embodiment in Fig. 13C as viewed in the line of sight of the user 230. In the example of this figure, the second image 2050 is a background image in which a plain, a mountain, and the sun are drawn.

[0206] Fig. 13D(3) is a diagram showing a state in which the second image 2050 and the floating in space image 3 are seen superimposed in the line of sight of the user 230, among the example of image display of this embodiment in Fig. 13C. Specifically, the bear character of the floating in space image 3 is seen superimposed in front of the background of the plains, mountains, and sun depicted in the second image 2050.

[0207] Here, when the space-floating image 3 and the second image 2050 are displayed simultaneously, it is desirable to pay attention to the balance of brightness between the two images in order to more suitably ensure the visibility of the space-floating image 3. If the second image 2050 is too bright compared to the brightness of the space-floating image 3, the display image of the space-floating image 3 will be transparent, and the second image 2050, which is the background, will be strongly visible through the transmitted image.

[0208] Therefore, the light source output of the spatially floating image 3 and the display image luminance of the display device 1, and the light source output of the display device displaying the second image 2050 and the display image luminance of the display device should be set so that at least the brightness per unit area of ​​the spatially floating image 3 at the display position of the spatially floating image 3 is greater than the brightness per unit area of ​​the image light reaching the display position of the spatially floating image 3 from the second image 2050.

[0209] In addition, since this condition only needs to be satisfied when the space-floating image 3 and the second image 2050 are displayed simultaneously, when switching from the first display mode in which the space-floating image 3 is not displayed and only the second image 2050 is displayed to the second display mode in which the space-floating image 3 and the second image 2050 are displayed 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 luminance of the display device. These controls may be realized by the control unit 1110 in Fig. 3 controlling the display device 1 and the display device that displays the second image 2050 (the transmissive self-luminous image display device 1650 in Fig. 4K or Fig. 4L or the second display device 1680 in Fig. 4M).

[0210] Furthermore, when controlling to reduce the brightness of the second image 2050 in switching from the above-mentioned first display mode to the above-mentioned second display mode, the brightness may be reduced uniformly across the entire screen of the second image 2050. Alternatively, instead of reducing the brightness uniformly across the entire screen of the second image 2050, the brightness reduction effect may be maximized in the portion where the object is displayed in the floating-in-space image 3, and the brightness reduction effect may be gradually relaxed around the portion. In other words, if the brightness reduction of the second image 2050 is realized only in the portion where the floating-in-space image 3 is superimposed on the second image 2050 and viewed, the visibility of the floating-in-space image 3 is sufficiently ensured.

[0211] Here, since the floating-in-space image 3 and the second image 2050 are displayed at positions with different depths, when the user 230 slightly changes his / her viewpoint, the position where the floating-in-space image 3 is superimposed on the second image 2050 changes due to parallax. Therefore, when the brightness is reduced unevenly across the entire screen of the second image 2050 in switching from the first display mode to the second display mode, it is not desirable to reduce the brightness sharply based on the contour of the object displayed in the floating-in-space image 3, but it is desirable to perform a gradation process of the brightness reduction effect, which changes the brightness reduction effect stepwise depending on the position as described above.

[0212] In addition, in the space-floating image display device 1000 where the position of the object displayed in the space-floating image 3 is approximately at the center of the space-floating image 3, the position where the brightness reduction effect of the gradation processing of the brightness reduction effect is the highest can be set to the center position of the space-floating image 3.

[0213] According to the image display process of this embodiment described above, the user 230 can visually recognize the space floating image 3 and the second image 2050 more favorably.

[0214] Note that when displaying the space-floating image 3, control may be performed so as not to display the second image 2050. Since the visibility of the space-floating image 3 is improved when the second image 2050 is not displayed, this is suitable for the space-floating image display device 1000 and the like in which the user must be able to reliably view the space-floating image 3 when the space-floating image 3 is displayed.

[0215] <Example 2> As the second embodiment of the present invention, an example of another configuration example of the space-floating image display device will be described. Note that the space-floating image display device according to this embodiment is obtained by changing the optical system stored in the space-floating image display device described in the first embodiment to the optical system shown in FIG. 14(1) or FIG. 14(2). In this embodiment, differences from the first embodiment will be described, and repeated explanations of the same configuration as the first embodiment will be omitted. Note that in the following description of this embodiment, the predetermined polarized light and the other polarized light are polarized waves whose phases differ from each other by 90°.

[0216] Fig. 14(1) is an example of an optical system and an optical path according to this embodiment. The optical system shown in Fig. 14(1) is configured to be more compact as a whole optical system by moving the display device 1 closer to the polarization separation member 101B in the optical system of Fig. 2C. In Fig. 14(1), the configurations with the same reference numerals as Fig. 2C are omitted from the repeated detailed description.

[0217] 14(1), similar to Fig. 2C, image light of a predetermined polarized light (P polarized light in the figure) emitted from display device 1 travels in a direction perpendicular to the image display surface of display device 1. Here, similar to Fig. 2C, polarization separation member 101B selectively transmits the predetermined polarized light (P polarized light in the figure) emitted from display device 1 and reflects the other polarized light (S polarized light in the figure).

[0218] Therefore, the image light of a predetermined polarization (P-polarized light in the figure) traveling in the vertical direction from the image display surface of the display device 1 passes through the polarization separation member 101B and reaches the retroreflector 2 to which the λ / 4 plate 21 is attached. The image light that is retroreflected by the retroreflector 2 and travels again toward the polarization separation member 101B is converted from the predetermined polarization (P-polarized light in the figure) at the time of emission from the display device 1 to the other polarization (S-polarized light in the figure) by passing through the λ / 4 plate 21 twice. The image light that travels again toward the polarization separation member 101B is the other polarization (S-polarized light in the figure), and is therefore reflected by the polarization separation member 101B toward the position where the user should be. The traveling direction of the image reflected by the polarization separation member 101B is determined based on the angle at which the polarization separation member 101B is arranged.

[0219] In the example of FIG. 14(1), the image light traveling toward the polarization separation member 101B is reflected at a right angle by the polarization separation member 101B and travels as shown in the figure. The image light reflected by the polarization separation member 101B forms a space-floating image 3A. The space-floating image 3A can be visually recognized by the user in the direction of the arrow A.

[0220] Here, due to the characteristics of retroreflection by the retroreflector 2, the optical path length of the image light emitted from the display device 1 until it reaches the retroreflector 2 is equal to the optical path length of the image light emitted from the retroreflector 2 until it reaches the formation position of the space floating image 3A. This relationship determines the formation position of the space floating image 3A in the traveling direction of the image light reflected by the polarization separation member 101B.

[0221] In the example of FIG. 14(1), the display device 1, the polarization separation member 101B, and the retroreflector 2 are arranged closer than in the example of FIG. 2C. This allows the entire optical system to be configured more compactly. However, the amount of the space-floating image 3A projecting from the optical system of FIG. 14(1) is not very large. For example, as an index of the amount of the space-floating image 3A projecting from the optical system, the distance from the position where the central light beam of the image light is reflected by the polarization separation member 101B to the position where the image light forms the space-floating image 3A is shown in the figure (L1 in the example of FIG. 14(1)).

[0222] In addition, in the polarization design of the optical system in Fig. 14(1), the characteristics of P polarization and S polarization may be interchanged. Specifically, a predetermined polarization of the image light emitted from the display device 1 may be S polarization, and the characteristics of P polarization and S polarization may be interchanged in the reflection characteristics of the polarization separation member 101B. In this case, the illustrated P polarization and S polarization are both reversed, but the optical design such as the optical path can be realized in exactly the same way.

[0223] Next, Fig. 14(2) shows another example of the optical system and the optical path according to this embodiment. The optical system in Fig. 14(2) is a modified version of the optical system in Fig. 14(1) in order to increase the amount of the floating image projected from the optical system while realizing the same compactness as the optical system in Fig. 14(1). In Fig. 14(2), the detailed description of the components with the same reference numerals as those in Fig. 14(1) will be omitted.

[0224] 14(2), similarly to FIG. 14(1), image light of a predetermined polarized light (P polarized light in the figure) emitted from display device 1 travels in a vertical direction from the image display surface of display device 1. Here, the polarization characteristics of polarization separation member 101B are arranged 90 degrees differently from FIG. 14(1). Image light of a predetermined polarized light (P polarized light in the figure) traveling in a vertical direction from the image display surface of display device 1 passes through polarization separation member 101B.

[0225] 14(1), a specular reflector 4 to which a λ / 4 plate 21B is attached is disposed after the image light passes through the polarization separation member 101B, rather than a retroreflector 2 to which a λ / 4 plate 21 is attached. Here, the reflection at the specular reflector 4 is specular reflection (also called regular reflection), not retroreflection.

[0226] Therefore, the image light that has passed through the polarization separation member 101B is specularly reflected by the specular reflector 4 to which the λ / 4 plate 21B is attached. The image light that has been specularly reflected by the specular reflector 4 and travels again toward the polarization separation member 101B has been converted from the specified polarization (P-polarized in the figure) at the time of emission from the display device 1 to the other polarization (S-polarized in the figure) by having passed twice through the λ / 4 plate 21. The image light that has traveled again toward the polarization separation member 101B is the other polarization (S-polarized in the figure), and is therefore reflected by the polarization separation member 101B.

[0227] Here, since the orientation of the polarization separation member 101B in FIG. 14(2) is different from that in FIG. 14(1), the image light reflected by the polarization separation member 101B travels in the opposite direction to the position where the user should be. A retroreflector 2 with a λ / 4 plate 21C attached is disposed at the destination of the image light reflected by the polarization separation member 101B. The image light is retroreflected by the retroreflector 2. The image light that is retroreflected by the retroreflector 2 and travels again toward the polarization separation member 101B has been converted from the other polarized light (S polarized light in the figure) to the specified polarized light (P polarized light in the figure) again by transmitting twice through the λ / 4 plate 21C.

[0228] The image light that travels back toward the polarization separation member 101B is a predetermined polarization (P polarization in the figure), so it passes through the polarization separation member 101B and travels directly toward the position where the user should be. The image light that passes through the polarization separation member 101B forms the space floating image 3B. The space floating image 3B can be visually recognized by the user in the direction of the arrow A.

[0229] 14(2), as in FIG. 14(1), due to the characteristics of retroreflection by the retroreflector 2, the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 is equal to the optical path length of the image light emitted from the retroreflector 2 to reach the formation position of the space floating image 3B. This relationship determines the formation position of the space floating image 3B in the traveling direction of the image light transmitted through the polarization separation member 101B.

[0230] 14(2), the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 is longer than the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 in FIG. 14(1). This is because in the optical system of FIG. 14(2), an optical path going back and forth between the polarization separation member 101B and the specular reflector 4, which does not exist in the optical system of FIG. 14(1), is added to the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2.

[0231] As a result, in the optical system of Figure 14(2), the distance from the position where the central light beam of the image light passes through the polarization separation member 101B to the position where the image light forms the space-floating image 3B (L2 in the example of Figure 14(2)) is significantly longer than the distance from the position where the central light beam of the image light is reflected by the polarization separation member 101B to the position where the image light forms the space-floating image 3A (L1 in the example of Figure 14(1)) in the optical system of Figure 14(1).

[0232] In addition, in the polarization design of the optical system in Fig. 14(2), the characteristics of P polarization and S polarization may be interchanged. Specifically, a predetermined polarization of the image light emitted from the display device 1 may be S polarization, and the characteristics of P polarization and S polarization may be interchanged in the reflection characteristics of the polarization separation member 101B. In this case, the illustrated P polarization and S polarization are both reversed, but the optical design such as the optical path can be realized in exactly the same way.

[0233] According to the optical system of Fig. 14(1) and Fig. 14(2) in the embodiment 2 of the present invention described above, a more compact optical system can be realized. In particular, according to the optical system of Fig. 14(2), it is possible to increase the amount of the floating image projecting from the optical system, while being a more compact optical system.

[0234] In addition, when the optical system of Fig. 14(1) or Fig. 14(2) is incorporated into a space-floating image display device, it can be realized by replacing the optical system in the space-floating image display device described in the first embodiment with the optical system of Fig. 14(1) or Fig. 14(2). Specifically, the optical system of Fig. 14(1) may be replaced with the optical system of the space-floating image display device of Fig. 4E, Fig. 4F, Fig. 4G, Fig. 4H, Fig. 4I, Fig. 4J, Fig. 4K, Fig. 4L, or Fig. 4M. In this case, since the optical system becomes compact, it is possible to make the housing of the space-floating image display device of each figure smaller.

[0235] Specifically, the optical system of FIG. 14(2) may be replaced with the optical system of the space-floating image display device of FIG. 4E, FIG. 4F, FIG. 4G, FIG. 4K, or FIG. 4L. In this case, it is possible to increase the amount of the space-floating image projected from the optical system. Also, since the optical system becomes compact, it is possible to make the housing of the space-floating image display device of each figure smaller.

[0236] <Example 3> As the third embodiment of the present invention, another configuration example of the space floating image display device will be described. In the description of the third embodiment, an image floating in space, such as in air or liquid (for example, underwater), is expressed by the term "space floating image". Instead of this term, it may be expressed as "spatial image", "space floating optical image of displayed image", etc. Furthermore, an image floating in air may be expressed as "aerial image", "image floating in air", "optical image floating in air of displayed image", etc. Furthermore, an image floating in liquid may be expressed as "image in liquid", "image floating in liquid", "optical image floating in liquid of displayed image", etc. The term "space floating image" mainly used in the description of the third embodiment is used as a representative example of these terms.

[0237] The space-floating image display device of the third embodiment is configured to form at least a part of the space-floating image in the liquid stored in the liquid storage tank using the optical system described in the first and second embodiments. More specifically, the liquid-floating image device of the third embodiment is configured to form at least a part of the space-floating image in the water stored in the water tank. In other words, the third embodiment is an example of an aspect in which the space-floating image display device is used as an aquarium device. The aquarium device here refers to a device for raising and viewing aquatic organisms such as fish in an aquarium.

[0238] In the description of the third embodiment, the left-right direction of the tank is the X direction, the front-rear direction (depth direction) is the Y direction, and the height direction (vertical direction) is the Z direction. In the following, differences from the first and second embodiments will be described, and the description of the same configuration as the first and second embodiments will be omitted.

[0239] Fig. 15 is a diagram showing an example of the configuration of a space-floating image display device according to Example 3. As shown in Fig. 15, a space-floating image display device 1000 according to this embodiment is disposed outside a water tank (liquid storage tank) 2000 in which a liquid 2100, such as water, is stored. In other words, the space-floating image display device 1000 includes a display device 1 and an optical system 1800 as separate entities from the water tank 2000.

[0240] Although not shown, the display device 1 and the optical system 1800 constituting the space-floating image display device 1000 are arranged in a housing. The internal configuration of the space-floating image display device 1000 shown in Fig. 15 is the same as the internal configuration shown in Fig. 3, except that it does not include the imaging unit 1180, the aerial operation detection sensor 1351, and the aerial operation detection unit 1350.

[0241] The aquarium 2000 has a bottom wall 2001 and a side wall 2002 standing around the bottom wall 2001. The side wall 2002 of the aquarium 2000 is formed of a transparent material such as glass or acrylic resin. The display device 1 and the optical system 1800 are disposed on the outside of the side wall 2002 of the aquarium 2000. In this example, the display device 1 and the optical system 1800 are disposed on the outside of a side wall 2002a that constitutes the rear side of the aquarium 2000.

[0242] The display device 1 and the optical system 1800 are disposed close to the aquarium 2000 so that a space-floating image 3C is generated inside the aquarium 2000. The display device 1 is installed facing vertically upward. This optical system 1800 corresponds to the optical system of FIG. 2A, in which the retroreflector 2 is disposed along the vertical direction, and the polarization separation member 101 provided on the transparent member 100 is disposed at an angle of approximately 45° with respect to the vertical direction. As a result, the optical system 1800 generates a space-floating image 3C inside the aquarium 2000 based on the image displayed on the display device 1. For example, when the aquarium 2000 is filled with a liquid 2100, which is water, the space-floating image display device 1000 generates a space-floating image 3C in the liquid 2100 (underwater).

[0243] Here, as described above, the optical path length from the image light emitted from the display device 1 to the retroreflector 2 is equal to the optical path length from the image light emitted from the retroreflector 2 to the position where the spatial floating image 3 is formed.

[0244] Therefore, for example, when the water tank 2000 does not contain the liquid 2100, the floating image 3C is formed at a position that satisfies the above relationship, for example, at a first position Y1 in the Y direction as shown by a two-dot chain line in FIG. 15. On the other hand, when the water tank 2000 contains the liquid 2100, the image light is refracted by the liquid 2100 in the water tank 2000. Therefore, the position at which the floating image 3C is formed is a second position Y2 on the +Y side of the first position Y1, as shown by a dotted line in FIG. 15. The display device 1 and the optical system 1800 that constitute the floating image display device 1000 are disposed outside the water tank 2000 so that the first position Y1 and the second position Y2 are both inside the water tank 2000.

[0245] As a result, regardless of whether liquid 2100 is stored in aquarium 2000, spatially floating image 3C is formed inside aquarium 2000. When observing the inside of aquarium 2000 from outside sidewall 2002b, which is the front side of aquarium 2000, that is, when observing the inside of aquarium 2000 in the direction of arrow A, a user can visually recognize spatially floating image 3C displayed inside aquarium 2000 as a bright image. And, for example, by displaying an image of aquatic life or the like as spatially floating image 3C, a user can enjoy viewing aquatic life in a simulated manner.

[0246] The arrangement of the display device 1 and the optical system 1800 can be changed as appropriate as long as the first position Y1 and the second position Y2 are within the aquarium 2000. For example, when an image of an aquatic organism such as a fish is displayed inside the aquarium 2000 as the spatially floating image 3C, the second position Y2 is set to a position near the center of the aquarium 2000 or the side wall 2002b on the front side of the aquarium 2000 in the Y direction. This makes it easier for the user to visually recognize the spatially floating image 3C of the aquatic organism. Also, for example, when an aquatic organism such as a fish is actually raised in the aquarium 2000 and an image of an aquatic plant or the like is displayed as the spatially floating image 3C as the background, the second position Y2 is set to a position near the side wall 2002a on the back side of the aquarium 2000 in the Y direction. This allows the user to enjoy viewing the aquatic organism raised with the spatially floating image 3C as the background.

[0247] In this example, the direction of the floating image 3C (the direction of the main ray of the image light indicated by the arrow in the figure) is set to be approximately horizontal. However, the direction of the floating image 3C does not necessarily have to be horizontal, and may be appropriately determined in consideration of, for example, the expected line of sight of the user. For example, the direction of the floating image 3C may be a direction intersecting the horizontal direction. More specifically, the direction of the floating image 3C may be diagonally upward from the horizontal direction, or diagonally downward from the horizontal direction.

[0248] 15, a chamfered portion 2003 is provided at the corner between bottom wall 2001 and side wall 2002a of water tank 2000. This chamfered portion 2003 is provided to avoid interference between the water tank 2000 and polarization separation member 101 provided on transparent member 100. If there is no interference between the polarization separation member 101 and water tank 2000, this chamfered portion 2003 does not need to be provided.

[0249] <Modification of the third embodiment> 16 is a diagram showing a modified example of the space-floating image display device 1000 of the third embodiment. The space-floating image display device 1000 shown in FIG. 16 is an example in which an optical system 1800 is placed in a water tank 2000. More specifically, in this example, a retroreflector 2 and a polarization separation member 101 constituting the optical system 1800 are placed in the water tank 2000. A λ / 4 plate 21 is provided on the incident surface of the retroreflector 2. The polarization separation member 101 is also adhered to a transparent member 100.

[0250] 16, the water tank 2000 is sufficiently filled with liquid 2100, and the retroreflector 2 is placed in the liquid 2100. However, depending on the amount of liquid 2100 stored in the water tank 2000, a part of the retroreflector 2 may be exposed outside the liquid 2100. Also, most of the polarization separation member 101 is placed in the liquid 2100, but the upper end (the end in the +Z direction) of the polarization separation member 101 is exposed outside the liquid 2100 (above the water surface). Of course, the entire polarization separation member 101 may be placed in the liquid 2100.

[0251] Moreover, the display device 1 is disposed on the outside of the bottom wall 2001 of the aquarium 2000. A transparent window 2004 made of a transparent material such as glass or acrylic resin is provided in an area of ​​the aquarium 2000 facing the display device 1, and the image light emitted from the display device 1 enters the aquarium 2000 through this transparent window 2004. As described above, the image light entered the aquarium 2000 is reflected by the polarization separation member 101 and enters the retroreflector 2. Moreover, the image light reflected by the retroreflector 2 passes through the polarization separation member 101 to form a spatially floating image 3C in the liquid 2100.

[0252] In addition, in a configuration in which the optical system 1800 is disposed in the liquid 2100, the distance that the image light travels in the liquid 2100 is longer than in a configuration in which the optical system 1800 is disposed outside the water tank 2000 (see FIG. 15). Therefore, the position where the floating image 3C is formed is a third position Y3 on the +Y side of the second position Y2 in the Y direction. The display device 1 and the optical system 1800 are disposed so that the third position Y3 is inside the water tank 2000.

[0253] Even in this configuration in which the optical system 1800 is disposed in the liquid 2100, the spatially floating image 3C can be displayed satisfactorily in the aquarium 2000. Therefore, by displaying an image of an aquatic organism such as a fish as the spatially floating image 3C, the user can enjoy viewing the aquatic organism in a simulated manner.

[0254] As an example, the transparent window 2004 is provided in an area of ​​the bottom wall 2001 of the aquarium 2000 facing the display device 1, but is not limited to this configuration. The transparent window 2004 may be formed, for example, over the entire surface of the bottom wall 2001 of the aquarium 2000. In other words, the entire bottom wall 2001 of the aquarium 2000 may be formed of a transparent material.

[0255] 16, a recess 2005 is provided in bottom wall 2001 of aquarium 2000, part of which is recessed into the inside of aquarium 2000. Transparent window 2004 is provided in a portion corresponding to this recess 2005, and display device 1 is housed in recess 2005. Note that as long as display device 1 can be placed outside bottom wall 2001, recess 2005 does not necessarily have to be provided in bottom wall 2001, and a configuration without recess 2005 is also possible. For example, a recess may be provided in the surface of a mounting stand on which aquarium 2000 is placed, and display device 1 may be placed in the recess of this mounting stand.

[0256] <Modification of Example 3> Fig. 17 is a diagram showing a modified example of the space-floating image display device 1000 of the third embodiment. The space-floating image display device 1000 shown in Fig. 17 is an example in which a part of the optical system 1800 is provided in the water tank 2000. More specifically, the transparent member 100 to which the polarization separation member 101 constituting the optical system 1800 is adhered is fixed to the side wall 2002a of the water tank 2000. In other words, the transparent member 100 to which the polarization separation member 101 is adhered is integrated with the side wall 2002a of the water tank 2000.

[0257] 17, a side wall 2002a constituting the rear side of the water tank 2000 is provided so as to be inclined toward the retroreflector 2. As an example, the side wall 2002a is inclined at an angle of about 45° with respect to the vertical direction. A transparent member 100 having a polarization separation member 101 adhered thereto is joined to the side wall 2002a.

[0258] In this example, the transparent member 100 is joined to the side wall 2002a of the water tank 2000, but the side wall 2002a may function as the transparent member 100. That is, the transparent member 100 to which the polarization separation member 101 is adhered may be provided integrally with the side wall 2002a of the water tank 2000. Also, the side wall 2002a only needs to have a portion that corresponds to the space floating image display device 1000 inclined, and may be inclined entirely or partially.

[0259] 17, the distance that the image light travels in the liquid 2100 is longer than in a configuration in which the optical system 1800 is disposed outside the water tank 2000 as a separate entity (see FIG. 15), and shorter than in a configuration in which the optical system 1800 is disposed in the liquid 2100 (see FIG. 16). Therefore, the position where the floating image 3C is formed is a fourth position Y4 that is on the +Y side of the second position Y2 and on the -Y side of the third position Y3. The display device 1 and the optical system 1800 are placed near the water tank 2000 so that the fourth position Y4 is inside the water tank 2000.

[0260] Even in this configuration in which the transparent member 100 to which the polarization separation member 101 is adhered is integrated with the side wall 2002a of the aquarium 2000, the spatially floating image 3C can be displayed satisfactorily within the aquarium 2000. Therefore, by displaying an image of an aquatic organism such as a fish as the spatially floating image 3C, the user can enjoy viewing the aquatic organism in a simulated manner.

[0261] Although the optical system 1800 corresponds to the optical system shown in Fig. 2A as the space floating image display device 1000 of the third embodiment, the configuration of the optical system 1800 is not particularly limited. The optical system 1800 may correspond to the optical systems shown in Figs. 2B to 2D, for example.

[0262] <Modification of the third embodiment> Fig. 18A is a diagram showing the configuration of a modified example of the space-floating image display device according to the third embodiment, and Fig. 18B is a diagram showing an example of a state in which a space-floating image is displayed inside a water tank. The space-floating image display device 1000 shown in Fig. 18A includes an imaging unit 1180A and an aerial operation detection sensor 1351A in addition to the configuration shown in Fig. 15. Note that, except for the imaging unit 1180A and the aerial operation detection sensor 1351A, the internal configuration of the space-floating image display device 1000 shown in Fig. 18A is the same as the internal configuration shown in Fig. 3.

[0263] The imaging unit 1180A and the aerial operation detection sensor 1351A are provided separately from the housing of the space-floating image display device 1000. The imaging unit 1180A is a camera having an image sensor, and captures the inside of the aquarium 2000 and the space around the aquarium 2000. As an example, the imaging unit 1180A is installed on the upper part of the aquarium 2000 facing the inside of the aquarium 2000. The imaging unit 1180A is configured to transmit an imaging signal to the space-floating image display device 1000 via, for example, a wired or wireless communication connection path. Based on the imaging result of this imaging unit 1180A, for example, the image control unit 1160 performs control to form the space-floating image 3C. Note that a plurality of imaging units 1180A may be provided as necessary, and the installation position of each imaging unit 1180A is not particularly limited.

[0264] In this example, the aerial operation detection sensor 1351A is provided as a liquid level detection sensor that detects the position of the liquid level 2101 of the liquid 2100 in the water tank 2000. The aerial operation detection sensor 1351A is composed of, for example, a distance sensor using ultrasonic waves, and is installed at the bottom of the water tank 2000 facing the inside (upper side) of the water tank 2000. A sensing signal that is the detection result by the aerial operation detection sensor 1351A is sent to the aerial operation detection unit 1350 (see FIG. 3). Based on this sensing signal, the aerial operation detection unit 1350 calculates the position of the liquid level 2101 of the liquid 2100 in the Z direction, etc. Note that the aerial operation detection sensor may be a distance sensor using electromagnetic waves or a liquid level gauge using a pressure sensor.

[0265] In the example shown in Fig. 18A and Fig. 18B, liquid 2100 is stored up to about half of the water tank 2000 in the Z direction (height direction). A liquid surface 2101 of the liquid 2100 is located in an image formation area S1 in which a floating-in-space image 3C is formed in the Z direction. In this case, the image displayed on the display device 1 can be displayed in the liquid 2100 in the water tank 2000 and in the air in the water tank 2000 above the liquid 2100. In other words, the image formation area S1 includes a submerged formation area S2 set in the liquid 2100 in the water tank 2000 and an aerial formation area S3 set in the air in the water tank 2000.

[0266] In other words, the floating image 3C may include a floating image 3Ca displayed in the submerged area (submerged display area) S2 in the aquarium 2000, and a floating image 3Cb displayed in the air-formed area (air-formed display area) S3 in the aquarium 2000. The floating image 3Ca and the floating image 3Cb have different display positions (formation positions) in the Y direction. As described above, the floating image 3Ca is formed at the second position Y2 in the Y direction, and the floating image 3Cb is formed at the first position Y1 in the Y direction. The floating image 3Ca may be formed in the entire submerged area S2 or in a part of the submerged area S2. Similarly, the floating image 3Cb may be formed in the entire air-formed area S3 or in a part of the air-formed area S3.

[0267] Here, when the floating image 3C includes the floating image 3Ca in liquid and the floating image 3Cb in air, it is preferable that a non-forming area S4 where no image is formed is provided between the liquid-formed area S2 where the floating image 3Ca is formed and the air-formed area S3 where the floating image 3Cb is formed. For example, near the liquid surface 2101 in the Z direction, image disturbances due to the shaking of the liquid surface 2101 are likely to occur. For this reason, it is preferable that a non-forming area S4 where the floating image 3C is not formed is provided between the liquid-formed area S2 and the air-formed area S3, that is, near the liquid surface 2101 in the Z direction. In other words, the non-forming area S4 is an area where the floating image 3C is transparent, and the part of the display device 1 corresponding to the non-forming area S4 is displayed in black.

[0268] The range of the non-formation region S4 is not particularly limited, but is preferably set to be wider than the range of pulsation of the liquid surface 2101 caused by the flow of the liquid 2100 in the water tank 2000. However, the non-formation region S4 does not have to be provided, and the submerged formation region S2 where the submerged floating image 3Ca is formed and the aerial formation region S3 where the aerial floating image 3Cb is formed may be set to be continuous in the Z direction.

[0269] Furthermore, the position (height) of the liquid surface 2101 of the liquid 2100 is not always constant and may change depending on the situation. For this reason, in this example, the position and range of the image formation region S1, more specifically, the positions and ranges of the submerged formation region S2 and the aerial formation region S3 are appropriately adjusted based on the position of the liquid surface 2101 of the liquid 2100.

[0270] In this example, the position of the liquid surface 2101 of the liquid 2100 in the Z direction is detected by the mid-air operation detection sensor 1351A and the mid-air operation detection unit 1350. Then, the image control unit 1160 performs various controls on the image signal input to the display device 1 (image display unit 1102) according to the position of the liquid surface 2101. That is, the positions and ranges of the submerged formation region S2 and the mid-air formation region S3 are appropriately adjusted according to the position of the liquid surface 2101 so that the vicinity of the liquid surface 2101 becomes a non-formation region S4. In other words, the display positions of the submerged image 3Ca and the mid-air image 3Cb are adjusted according to the water level of the liquid stored in the liquid storage tank, that is, the water tank 2000, that is, the position of the liquid surface 2101.

[0271] In addition, when the floating image 3C in space includes the floating image 3Ca in liquid and the floating image 3Cb in air, the contents of the floating image 3Ca in liquid and the floating image 3Cb in air can be different. In other words, the floating image 3Ca in liquid and the floating image 3Cb in air can be independent images.

[0272] 18B, an image of a fictional character "mermaid" which is an object is displayed as a floating-in-liquid image 3Ca in the liquid-formed region S2, and an image of information for the user (information to be communicated to the user) is displayed as a floating-in-air image 3Cb in the air-formed region S3. However, this display is merely an example, and the image of the character may be displayed as a floating-in-air image 3Cb, or information for the user may be displayed as a floating-in-liquid image 3Ca.

[0273] The content of the information displayed as the floating image 3Cb is not particularly limited, but may include, for example, the date and time, the weather and air temperature, the temperature (water temperature) and water quality of the liquid 2100, the communication status, etc. Note that the communication status here refers to, for example, the Wi-Fi connection status when the communication unit 1132 (see FIG. 3) has a Wi-Fi communication interface and image data, etc. is transmitted and received by communication via the communication unit 1132.

[0274] Furthermore, for example, when an aquatic creature 4000 such as a fish is actually kept in the aquarium 2000, the display position of the submerged floating image 3Ca in the liquid formation area S2 may be changed as appropriate according to the position and movement of the aquatic creature 4000. For example, when an image of a character "mermaid" is displayed as the submerged floating image 3Ca, the submerged floating image 3Ca may be moved in accordance with the movement of the aquatic creature 4000 so that the submerged floating image 3Ca is always displayed near the aquatic creature 4000. For example, by identifying the position of the aquatic creature 4000 based on the imaging result of the imaging unit 1180A, the display position of the submerged floating image 3Ca can be changed in accordance with the movement of the aquatic creature 4000.

[0275] Furthermore, the content of the floating image 3Ca in liquid may be changed according to the position and movement of the aquatic organism kept in the aquarium 2000. The content of the floating image 3Ca in liquid and the floating image 3Cb in air are not particularly limited. As the floating image 3Ca in liquid, in addition to the image of the character as described above, for example, an image of an aquatic organism such as a fish or aquatic plants may be displayed. Also, when an aquatic organism is kept in the aquarium 2000, the trajectory of the movement of the aquatic organism may be displayed as the floating image 3Ca in liquid. Furthermore, for example, information such as the name or nickname of the aquatic organism kept may be displayed near the aquatic organism as the floating image 3Ca in liquid. Alternatively, as the floating image 3Ca in liquid, an explanatory image of the aquatic organism kept in the aquarium 2000 may be displayed at a predetermined position, and an arrow pointing to the aquatic organism being explained in the image may also be displayed. Furthermore, an image of an aquatic organism in liquid 2100 may be captured by imaging section 1180A, and an enlarged image of a portion of the aquatic organism may be displayed as sub-liquid floating image 3Ca.

[0276] Incidentally, red light is easily absorbed in the liquid 2100 (underwater), and the red color of the floating-in-liquid image 3Ca tends to be faint. For this reason, when displaying the floating-in-space image 3C, it is preferable to adjust the color of the floating-in-liquid image 3Ca, taking into consideration that red light is absorbed by the liquid 2100. More specifically, when displaying the floating-in-liquid image 3Ca in the liquid 2100, it is preferable to adjust the green and blue colors to be faint and set the RGB values ​​appropriately.

[0277] Furthermore, turning on and off the light or abrupt changes in light (e.g., changes in brightness or color) are likely to cause stress to aquatic organisms. For this reason, it is preferable that the image control unit 1160 gradually (stepwise) changes the light state when changing the submerged floating image 3Ca. Furthermore, the image control unit 1160 may not display the submerged floating image 3Ca in an area where aquatic organisms exist. In other words, even in the submerged formation area S2, an area where aquatic organisms such as fish exist may be a non-formation area where the submerged floating image 3Ca is not formed. Specifically, the position of the aquatic organism may be identified based on the imaging result of imaging the inside of the aquarium 2000 by the imaging unit 1180A, and the non-formation area may be set according to the position (movement) of the aquatic organism.

[0278] In such a configuration, the spatially floating image 3C can be more appropriately displayed in the aquarium 2000. For example, even if aquatic life is kept in the aquarium 2000, the spatially floating image 3C can be appropriately displayed so as not to impede the observation of the aquatic life. In addition, the stress given to the aquatic life can be suppressed. This makes it easier for the user to enjoy the appreciation of the aquatic life.

[0279] In this example, the position of the liquid surface 2101 of the liquid 2100 is detected based on the sensing signal of the aerial operation detection sensor 1351A, but there is no particular limitation on the method for detecting the position of the liquid surface 2101. For example, the position of the liquid surface 2101 can also be detected based on the imaging results by the imaging section 1180A without using the aerial operation detection sensor 1351A.

[0280] <Modification of the third embodiment> Fig. 19 is a diagram showing the configuration of a space-floating image display system according to Example 3. The space-floating image display system 3000 shown in Fig. 19 includes an aquarium device 3100 including a space-floating image display device installed in a user's home or the like, a live camera 3200 installed in a location other than the aquarium device 3100, for example, an aquarium, and a server device 3400 connected to the space-floating image display device and the live camera 3200 via the Internet 3300.

[0281] Aquarium device 3100 including the space floating image display device includes communication unit 1900, and can communicate with communication device 3310 connected to Internet 3300 via communication unit 1900. Communication unit 1900 is an example of communication unit 1132 in Fig. 3. Aquarium device 3100 including the space floating image display device can communicate with server device 3400 via communication device 3310 and Internet 3300.

[0282] Meanwhile, the live camera 3200 also includes a communication unit 3210, and is capable of communicating with a communication device 3320 connected to the Internet 3300 via the communication unit 3210. The live camera 3200 is capable of communicating with a server device 3400 via the communication device 3320 and the Internet 3300.

[0283] 19 shows an example in which the communication between the communication unit 1900 and the communication device 3310 and the communication between the communication unit 3210 and the communication device 3320 are wireless, but the communication may be wired. Also, the communication path from each of the communication units 1900, 3210 to the Internet 3300 may include a mixture of wired and wireless portions.

[0284] The aquarium device 3100 including the space-floating image display device has the same configuration as the example shown in FIG. 18A, and includes a display device 1 and an optical system 1800A, and forms a space-floating image 3C inside the aquarium tank (second liquid storage tank) 2000. However, the optical system 1800A corresponds to the optical system shown in FIG. 2D. In the aquarium device 3100 including the space-floating image display device shown in FIG. 19, the image displayed on the display device 1 is displayed as a space-floating image 3C at a position that is geometrically symmetrical with respect to the retroreflector 5. Of course, the optical system 1800A is not limited to this configuration, and may be equivalent to the optical system shown in FIG. 2A to FIG. 2C. Note that the aquarium tank 2000 may or may not actually house aquatic organisms.

[0285] A live camera 3200, which is an imaging device, captures images of aquatic organisms 4100 kept in liquid 3600 (underwater) in an aquarium tank (first liquid storage tank) 3500 at an aquarium. The live cameras 3200 are installed, for example, corresponding to a plurality of aquariums 3500, and the plurality of live cameras 3200 capture images of different kinds of aquatic organisms 4100. Images captured by each live camera 3200 are transmitted to a server device 3400 via a communication device 3320 and the Internet 3300. The server device 3400 accumulates the images captured by the live cameras 3200 for a certain period of time, for example.

[0286] In this space-floating image display system 3000, for example, when the aquarium device 3100 including the space-floating image display device is started by the user, the captured image stored in the server device 3400, for example, an image of an aquatic organism 4100, is transmitted to the aquarium device 3100 including the space-floating image display device. The captured image captured by the live camera 3200 may be transmitted in real time to the aquarium device 3100 including the space-floating image display device via the server device 3400. The captured image transmitted to the aquarium device 3100 including the space-floating image display device is displayed on the display device 1, and is displayed as a space-floating image 3C in the liquid 2100 in the aquarium tank 2000 via the optical system 1800A including the retroreflector 5. This allows the user to view the aquatic organisms kept in the aquarium at any place, such as at home.

[0287] In addition, the aquarium device 3100 including the spatially floating image display device has a live camera aquarium change function. In other words, the aquarium device 3100 including the spatially floating image display device is configured to be able to appropriately select the type of aquatic life to be displayed as the spatially floating image 3C. The aquarium device 3100 including the spatially floating image display device is configured to be able to switch the image of the aquatic life to be displayed as the spatially floating image 3C in response to, for example, an input operation by the user to the operation input unit 1107.

[0288] <Operation of the space floating image display device according to the third embodiment> Next, an operation example of the space-floating image display device according to the third embodiment shown in Fig. 18A will be described. Fig. 20 is a flowchart showing an example of the operation of the space-floating image display device. Fig. 21 is a diagram illustrating a judgment item A judged in step S01 of Fig. 20, and judgment conditions 1 and 2 for the judgment item A. Fig. 22 is a diagram illustrating the contents of the second mode set in step S03 of Fig. 20.

[0289] The space floating image display device 1000 performs a judgment process for making a judgment on a preset judgment item A, and a mode selection process for selecting a display mode of the space floating image 3C based on the judgment result of the judgment process. As an example, the judgment process and the mode selection process are performed by, for example, the control unit 1110. That is, in this example, the control unit 1110 functions as a process execution unit that executes the judgment process and the mode selection process. The mode selection process for selecting the display mode can also be called a mode switching process for switching the display mode.

[0290] For example, when the power supply of the space-floating image display device 1000 is turned on and the control of the space-floating image display device is started, a judgment process is executed at a predetermined timing, for example, at regular intervals (step S01). In this judgment process, it is judged whether the judgment item A satisfies a preset judgment condition 1 or a judgment condition 2. If it is judged that the judgment item A satisfies the judgment condition 1 (step S01: judgment result [1]), the process proceeds to step S02, where the first mode, which is the normal mode, is selected as the display mode of the space-floating image 3C. On the other hand, if it is judged that the judgment item A satisfies the judgment condition 2 (step S01: judgment result [2]), the process proceeds to step S03, where the second mode, which is different from the normal mode, is selected as the display mode of the space-floating image 3C. For example, if the current display mode is the first mode, the display mode is switched from the first mode to the second mode in step S03.

[0291] Specific examples of the judgment process and the mode selection process will be described below with reference to Fig. 21 and Fig. 22. As described above, in the judgment process, it is judged whether a predetermined judgment item A satisfies judgment condition 1 or judgment condition 2. The contents of these judgment item A, judgment condition 1, and judgment condition 2 are not particularly limited and may be set arbitrarily, and examples thereof include the examples (judgment examples 1 to 7) shown in Fig. 21.

[0292] <Judgment Example 1> The judgment item A of the judgment example 1 is "current time". The "current time" is acquired from outside the space floating image display device 1000 via, for example, wireless communication. However, the method of acquiring the current time is not particularly limited. In addition, the judgment condition 1 is "the current time has passed the first time t1", and the judgment condition 2 is "the current time has passed the second time t2". The first time t1 and the second time t2 are times preset by the user.

[0293] This judgment example 1 is a so-called timer setting function, and when the current time reaches a first time t1, it is judged that judgment condition 1 is satisfied (step S01: judgment result [1]), and the first mode is selected as the display mode (step S02). As an example, when the first mode is selected as the display mode, the floating in space image 3C including the floating in liquid image 3Ca and the floating in air image 3Cb is displayed in the aquarium 2000. Furthermore, when the current time reaches a second time t2, it is judged that judgment condition 2 is satisfied (step S01: judgment result [2]), and the second mode is selected as the display mode (step S03).

[0294] Here, the setting contents of the second mode are not particularly limited and may be set arbitrarily, for example, examples (setting examples 1 to 8) shown in Fig. 22 are given. As the second mode in judgment example 1, for example, setting examples 1, 2, 3, 7, etc. are likely to be set.

[0295] When the second mode is in setting example 1, when the current time becomes the second time t2, the floating-in-liquid image 3Ca is hidden and only the floating-in-air image 3Cb is displayed. That is, until the current time passes the second time t2 and becomes the first time t1 again, only the floating-in-air image 3Cb is displayed in the aquarium 2000. Also, when the second mode is in setting example 2, when the current time becomes the second time t2, the floating-in-air image 3Cb is hidden and only the floating-in-liquid image 3Ca is displayed. That is, until the current time passes the second time t2 and becomes the first time t1 again, only the floating-in-liquid image 3Ca is displayed in the aquarium 2000.

[0296] In other words, in setting examples 1 and 2, the display modes include a first mode in which the floating image 3C is displayed both in the liquid 2100 of the aquarium 2000 and in the air, and a second mode in which the floating image 3C is displayed either in the liquid 2100 of the aquarium 2000 or in the air.

[0297] In this way, by changing the display state of the space floating image 3C according to the current time, it is possible to appropriately display the space floating image 3C within the aquarium 2000 while suppressing the power consumption of the space floating image display device 1000.

[0298] Also, when the second mode is setting example 3, the floating image 3C is displayed with red, green, and blue image light when the current time is between the first time t1 and the second time t2, but when the current time passes the second time t2, the floating image 3C is displayed with only blue image light, or with blue and green image light. That is, in setting example 3, the display modes include a first mode in which the floating image 3C displayed in the liquid 2100 of the aquarium 2000 is formed with red, green, and blue image light, and a second mode in which the floating image 3C displayed in the liquid 2100 of the aquarium 2000 is formed with blue light, or with blue and green light.

[0299] By displaying the floating image 3C with only blue light or with blue and green light, it is possible to reduce power consumption while creating an underwater atmosphere. It is also known that blue light is effective for growing coral. Therefore, when growing coral in the aquarium 2000, if the second mode is set to setting example 3, it is possible to achieve the effect of promoting the growth of coral while reducing power consumption.

[0300] In addition, when the second mode is the setting example 7, when the current time becomes the second time t2, both the floating image in liquid 3Ca and the floating image in air 3Cb are hidden. For example, the floating image in space 3C can be displayed during the daytime and hidden during the nighttime. This allows the biorhythm of the aquatic creatures kept in the aquarium 2000 to be adjusted. In addition, the power consumption of the floating image display device 1000 can be further reduced. However, even while the floating image in space 3C is hidden, the main power supply of the floating image display device 1000 is turned on and various sensors are functioning.

[0301] Also, the time to feed the aquatic creatures kept in the liquid 2100 of the aquarium 2000 may be set as the second time t2, and setting example 6 may be set as the second mode. As a result, when the current time becomes the second time t2, information indicating that it is time to feed the aquatic creatures in the aquarium 2000 is displayed as the spatially floating image 3C. That is, in this example, the display modes include a mode in which information indicating that it is time to feed the aquatic creatures is displayed as the spatially floating image 3C. This makes it possible to clearly notify the user that it is time to feed the aquatic creatures.

[0302] When displaying information for the user, such as feeding time or device error information, as floating image 3C, it is preferable to display floating image 3C in the air above aquarium 2000. In other words, it is preferable to display information for the user as floating image 3Cb within aquarium 2000. This allows various pieces of information to be notified to the user in an easier-to-understand manner.

[0303] <Judgment Example 2> In the second judgment example, judgment item A is "detection of a person near the aquarium", judgment condition 1 is "detected", and judgment condition 2 is "not detected". In the second judgment example, for example, the presence or absence of a person near the aquarium 2000 is judged based on an image captured by the imaging unit 1180A. Then, when the presence of a person is detected near the aquarium 2000, it is judged that the first judgment condition is satisfied (step S01: judgment result [1]), and the first mode is selected as the display mode (step S02). As an example, a floating-in-space image 3C including a floating-in-liquid image 3Ca and a floating-in-air image 3Cb is displayed inside the aquarium 2000.

[0304] On the other hand, if the presence of a person is not detected near the aquarium 2000, it is determined that the judgment condition 2 is satisfied (step S01: judgment result [2]), and the second mode is selected as the display mode (step S03). In this manner, in judgment example 2, the presence or absence of a person near the aquarium 2000 is determined from the detection result (imaging result) by the imaging unit 1180A as a human sensor, and the first mode or the second mode is selected depending on the judgment result.

[0305] As the second mode in the judgment example 2, for example, the setting examples 1 and 7 are likely to be set. When the second mode is the setting example 1, only the floating image 3Cb is displayed in the aquarium 2000 while the presence of a person is not detected near the aquarium 2000. When the second mode is the setting example 7, the floating image 3C is not displayed while the presence of a person is not detected near the aquarium 2000. This makes it possible to more effectively suppress the power consumption of the floating-in-space image display device 1000.

[0306] Note that the imaging unit 1180A is given as an example of a human presence sensor, and the presence or absence of a person near the aquarium 2000 can be detected by various types of human presence sensors. Examples of human presence sensors include those that use infrared rays, visible light, ultrasonic waves, etc. In addition, in the determination example 2, when determining the presence or absence of a person, it may be determined that the person is a specific person, for example, a registered user, by face recognition or the like.

[0307] <Judgment Example 3> The judgment item A of the judgment example 3 is "detection time of a person near the aquarium", the judgment condition 1 is "detection time passes a first period t11", and the judgment condition 2 is "detection time passes a second period t12". In this judgment example 3, for example, the length of time (detection time) during which the presence of a person is continuously detected near the aquarium 2000 is judged from the detection result (imaging result) of the imaging unit 1180A. When this detection time passes a preset first period t11, it is judged that a person (observer) is present observing the inside of the aquarium 2000. In other words, it is judged that the judgment condition 1 is satisfied. (Step S01: Judgment result [1]). Then, the first mode is selected as the display mode (Step S02), and as an example, the floating-in-liquid image 3Ca and the floating-in-air image 3Cb are displayed in the aquarium 2000.

[0308] Moreover, when the detection time has elapsed a preset second period t12 (>first period t11), it is determined that the judgment condition 2 is satisfied (step S01: judgment result [2]), and the second mode is selected as the display mode (step S03: judgment result [2]). Thus, in judgment example 3, the presence or absence of a person in the vicinity of the aquarium 2000 is determined from the detection result of the imaging unit 1180A as a human sensor, and the first mode or the second mode is selected according to the judgment result.

[0309] As the second mode in the determination example 3, for example, setting examples 1, 7, etc. are likely to be set. When the second mode is setting example 1, when the detection period has passed the second period t12, only the floating image 3Cb is displayed in the aquarium 2000. As an example, in order to make it easier for the observer to observe the aquatic organisms kept in the aquarium 2000, after the floating image 3Ca in the liquid is displayed for a certain period, the floating image 3Ca in the liquid is hidden and only the floating image 3Cb is displayed. Also, when the second mode is setting example 7, when the detection period has passed the second period t12, the floating image 3Ca in the liquid and the floating image 3Cb in the air are hidden.

[0310] <Judgment Example 4> In the determination example 4, the determination item A is "selection by the user", the determination condition 1 is "selection of the first mode", and the determination condition 2 is "selection of the second mode". The method for selecting the display mode by the user is not particularly limited, and examples include an input operation by the user to the operation input unit 1107, or a voice input to the voice input unit 1139 such as a microphone. Also, for example, the display mode may be selected by operating an external device such as a remote controller or a wireless device.

[0311] That is, in the judgment example 4, the first mode or the second mode is appropriately selected as the display mode according to the selection by the user. When the first mode is selected as the display mode, for example, the floating in liquid image 3Ca and the floating in air image 3Cb are displayed in the aquarium 2000. As the second mode in the judgment example 4, for example, the above-mentioned setting examples 1, 2, 3, 7, etc. are likely to be set. Note that the setting examples 1, 2, 3, and 7 are explained in the judgment example 1, so the explanation here is omitted.

[0312] <Judgment Example 5> The judgment item A of judgment example 5 is "detection of shaking by the attitude sensor", the judgment condition 1 is "no shaking is detected", and the judgment condition 2 is "shake is detected".

[0313] As described above, the space floating image display device 1000 includes an attitude sensor 1113. The attitude sensor 1113 is a sensor configured by a gravity sensor or an acceleration sensor, or a combination of these, and detects the attitude in which the space floating image display device 1000 is installed. In the determination example 5, when the attitude sensor 1113 detects shaking so much that the liquid 2100 in the water tank 2000 overflows, for example, it is determined that the determination condition 2 is satisfied, and the second mode is selected as the display mode. On the other hand, while the attitude sensor 1113 does not detect a predetermined shaking, it is determined that the determination condition 1 is satisfied, and the first mode is selected as the display mode.

[0314] As an example, when the detection value of the gravity sensor or acceleration sensor constituting the attitude sensor 1113 is smaller than a preset first threshold, it is determined that the judgment condition 1 is satisfied (step S01: judgment result [1]). Then, the first mode is selected as the display mode (step S02).

[0315] On the other hand, when the detection value of the attitude sensor 1113 exceeds the first threshold, it is determined that the judgment condition 2 is satisfied (step S01: judgment result [2]), and the second operation mode is selected as the display mode (step S03). As the second mode in judgment example 5, for example, setting example 8 is likely to be set.

[0316] When the second mode is set to the setting example 8, while the attitude sensor 1113 does not detect a predetermined shaking (while the first mode is selected), the space-floating image 3C is displayed in the water tank 2000. On the other hand, when the attitude sensor 1113 detects a predetermined shaking, the space-floating image 3C is hidden, and the main power supply of the space-floating image display device 1000 is cut off. This makes it possible to prevent leakage of electricity in the space-floating image display device 1000 even if the liquid 2100 in the water tank 2000 spills outside.

[0317] <Judgment Example 6> Judgment item A in judgment example 6 is "operational state of the device," judgment condition 1 is "operating normally," and judgment condition 2 is "not operating normally."

[0318] In the space-floating image display device 1000, for example, the control unit 1110 or the like constantly or periodically monitors whether or not an abnormality occurs in the hardware and software of the space-floating image display device 1000. In the judgment example 6, if the operating state of the space-floating image display device 1000 is normal, it is judged that the judgment condition 1 is satisfied (step S01: judgment result [1]), and the first mode is selected as the display mode (step S02). On the other hand, if an abnormality is detected in the operating state of the space-floating image display device 1000, it is judged that the judgment condition 2 is satisfied (step S01: judgment result [2]), and the second mode is selected as the display mode (step S03). As the second mode in the judgment example 6, for example, the setting example 8 is likely to be set. The setting example 8 has been explained in the judgment example 5, so a duplicate explanation will be omitted.

[0319] Furthermore, control unit 1110 may determine whether or not maintenance of aquarium 2000 is necessary based on the imaging result of imaging unit 1180A, and may determine that the operating state of the device is not normal if maintenance is necessary. That is, as one of determination example 6, when aquarium 2000 does not require maintenance, it may determine that determination condition 1 is satisfied, and when aquarium 2000 requires maintenance, it may determine that determination condition 2 is satisfied.

[0320] In this case, the second mode is likely to be set to, for example, setting example 5. When the second mode is setting example 5, if it is determined that it is time for maintenance of the aquarium 2000 based on the imaging result of the imaging unit 1180A, information to that effect is displayed as floating-in-liquid image 3Ca or floating-in-air image 3Cb. That is, in this example, the display mode includes a mode in which information indicating to the user that it is time for maintenance of the aquarium 2000 is displayed as floating-in-space image 3C. Note that maintenance of the aquarium 2000 includes, for example, replacement of the liquid 2100, cleaning of the aquarium 2000, replacement of consumables such as a filter for filtering the liquid 2100, and the like.

[0321] <Judgment Example 7> Judgment item A of judgment example 7 is "liquid level position (height) ha", judgment condition 1 is "liquid level position (height) ha is equal to or greater than a set threshold h1", and judgment condition 2 is "liquid level position (height) ha is less than a set threshold h1". The method of detecting the height ha of the liquid level 2101 is not particularly limited. The height ha of the liquid level 2101 can be calculated based on, for example, the imaging result of the imaging unit 1180A or the detection result of the aerial operation detection sensor (liquid level detection sensor) 1351A.

[0322] In this judgment example 7, when the position of the liquid level 2101 of the liquid 2100 in the water tank 2000, in other words, the height ha from the bottom wall 2001 of the water tank 2000 to the liquid level 2101 of the liquid 2100 (see FIG. 18A) is equal to or greater than a preset threshold value h1, it is judged that the judgment condition 1 is satisfied (step S01: judgment result [1]). Then, the first mode is selected as the display mode (step S02). On the other hand, when the height ha of the liquid level 2101 is less than the set height h1, it is judged that the judgment condition 2 is satisfied (step S01: judgment result [2]), and the second mode is selected as the display mode (step S03).

[0323] As the second mode in the determination example 7, for example, the setting example 4 and the like are likely to be set. When the second mode is the setting example 4, when the height ha of the liquid level 2101 becomes less than the set height h1, information that the liquid 2100 in the aquarium 2000 is insufficient is displayed in the aquarium 2000 as the floating in liquid image 3Ca or the floating in air image 3Cb. That is, in the determination example 7, the display mode includes a mode in which information indicating that the liquid 2100 in the aquarium 2000 is less than a preset amount is displayed as the floating in space image 3C. Note that while the first mode is selected as the display mode, the information that the liquid 2100 is insufficient is not displayed. This makes it possible to easily notify the user that the liquid 2100 in the aquarium 2000 is insufficient, and to prompt the user to add the liquid 2100 or replace the liquid 2100 at an appropriate timing.

[0324] Although specific examples of the judgment process and the mode selection process have been described above, the judgment process and the mode selection process are not limited to the above examples. For example, the setting contents of the second mode are not limited to the setting examples 1 to 8 shown in FIG. 22, and can be set appropriately as necessary. For example, when the space floating image display device 1000 constituting the aquarium device includes the second display device 1680 as shown in FIG. 4M, and the first mode is set to "ON for the second display device," the second mode may be set to "OFF (non-display) for the second display device."

[0325] Also, as an example, the first and second display modes are selected based on the determination result in the determination process, but the number of display modes to be selected is not limited to two. Three or more display modes may be selected based on the determination result in the determination process.

[0326] Although various embodiments of the present invention have been described in detail, the present invention is not limited to the above-mentioned embodiments. The present invention includes various modified examples. For example, the above-mentioned embodiments are detailed descriptions of the entire system in order to easily explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0327] 1...display device, 2, 5...retroreflector (retroreflector), 3...spatial image (space-floating image), 105...window glass, 100...transparent member, 101...polarized light separation member, 101B...polarized light separation member, 12...absorptive polarizer, 13...light source device, 54...light direction conversion panel, 151...retroreflector, 102, 202...LED substrate, 203...light guide, 205...reflective sheet, 206, 270...phase difference plate, 271...reflector, 230...user, 1000...space-floating image display device, 1110...control unit, 1160...image control unit, 1180, 1180A...imaging unit, 1102...image display unit, 1350...air operation detection unit, 1351...air operation detection sensor, 1351A...air operation detection sensor (liquid level detection sensor), 2000...liquid storage tank (aquarium, second liquid storage tank), 2100...liquid, 2101...liquid level, 3000...space floating image display system, 3100...aquarium device, 3200...live camera (imaging device), 3400...server device, 3500...aquarium (first liquid storage tank)

Claims

1. A space floating image display device, An image processing section; a display unit that displays the image that has been processed by the image processing unit; an optical system for generating a space floating image based on the image displayed by the display unit; Equipped with At least a part of the floating image in space is formed in the liquid stored in the liquid storage tank. A floating image display device.

2. 2. The space floating image display device according to claim 1, The floating image includes a floating image formed in the liquid and a floating image formed in the air above the liquid, The floating-in-liquid image and the floating-in-air image are images independent of each other. A floating image display device.

3. 2. The space floating image display device according to claim 1, The floating image includes a floating image formed in the liquid and a floating image formed in the air above the liquid, a non-formation area in which the floating image is not formed is provided between the liquid formation area in which the floating image is formed and the air formation area in which the air floating image is formed; A floating image display device.

4. 2. The space floating image display device according to claim 1, The floating image includes a floating image formed in the liquid and a floating image formed in the air above the liquid, adjusting a display position or a display range of the floating-in-liquid image and the floating-in-air image according to a level of the liquid stored in the liquid storage tank; A floating image display device.

5. 2. The space floating image display device according to claim 1, the optical system includes a polarization separation member; the polarization separation member is disposed in the liquid stored in the liquid storage tank, A floating image display device.

6. 2. The space floating image display device according to claim 1, the optical system includes a polarization separation member; The polarization separation member is disposed in the air outside the liquid storage tank. A floating image display device.

7. 2. The space floating image display device according to claim 1, the optical system includes a retroreflector; The retroreflector is disposed in the liquid stored in the liquid storage tank. A floating image display device.

8. 2. The space floating image display device according to claim 1, the optical system includes a retroreflector; The retroreflector is disposed in the air outside the liquid storage tank. A floating image display device.

9. 2. The space floating image display device according to claim 1, A control unit is provided, The control unit: A determination process for determining whether a preset determination condition is satisfied; and executing a mode selection process for selecting a display mode of the space floating image based on a determination result of the determination process. A floating image display device.

10. 10. The space floating image display device according to claim 9, Equipped with a human presence sensor to detect people, The control unit is the determination process determines whether or not a person is present near the liquid storage tank based on a detection result of the human presence sensor. A floating image display device.

11. 10. The space floating image display device according to claim 9, Equipped with a human presence sensor to detect people, The control unit is the determination process includes determining a period during which a person is detected near the liquid storage tank based on a detection result of the human presence sensor; A floating image display device.

12. 10. The space floating image display device according to claim 9, The control unit is As the determination process, it is determined whether or not the current time is a preset time. A floating image display device.

13. 10. The space floating image display device according to claim 9, The floating image includes a floating image formed in the liquid and a floating image formed in the air above the liquid, The display mode includes: a first mode for displaying the floating-in-liquid image and the floating-in-air image; and a second mode for displaying one of the floating-in-liquid image or the floating-in-air image. A floating image display device.

14. 10. The space floating image display device according to claim 9, The display mode includes: A mode in which information indicating that it is time for maintenance of the liquid storage tank is displayed as the floating image in space is included. A floating image display device.

15. an imaging device for imaging the aquatic organisms kept in the liquid of the first liquid storage tank; A space floating image display device having a display unit that displays an image and an optical system that generates a space floating image based on the image displayed by the display unit; A server device connected to the imaging device and the space-floating image display device via a network, receiving images captured by the imaging device, and transmitting the images to the space-floating image display device; Equipped with The space floating image display device displays the photographed image transmitted by the server device on the display unit, and forms the space floating image based on the photographed image in the liquid of the second liquid storage tank. A floating image display system.

Images