Floating image display device

Abstract

To provide a more appropriate floating image display device which contributes to sustainable development goals of "3. good health and well-being for all," "9. building a foundation for industry and technological innovation," and "11. creating sustainable cities."SOLUTION: A floating image display device is provided, comprising an image display device 1; a retroreflective module 200 having a polarization separation member 101, λ / 4 plate 21, and retroreflective member 2; and a housing 1190 accommodating the above mentioned. A first angle (A) between the polarization separation member 101 and the image display device 1 is different from a second angle (B') between the polarization separation member 101 and the retroreflective module 200.SELECTED DRAWING: Figure 15A

Description

[Technical Field]

[0001] The present invention relates to a floating-in-the-air image display device. [Background technology]

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

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

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

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

[0006] To solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above problems, one example of which is as follows. A floating-in-the-air image display device according to an embodiment is a floating-in-the-air image display device that displays a floating-in-the-air image, and includes: an image display device; a polarization separation member that reflects image light of a specific polarization from the image display device and transmits image light of the other polarization; a retroreflective module having a λ / 4 plate and a retroreflective member that retroreflects the reflected image light of the specific polarization from the polarization separation member and converts it into image light of the other polarization; and a housing that holds the image display device, the polarization separation member, and the retroreflective module. The image light of the other polarization from the retroreflective module is transmitted through the polarization separation member to form a floating-in-the-air image that is a real image at a predetermined position outside the housing, and a first angle made by the image display device with respect to the polarization separation member and a second angle made by the retroreflective module with respect to the polarization separation member are different from the first angle. [Effects of the Invention]

[0007] According to the present invention, a more suitable floating-in-the-air image display device can be realized. Other problems, configurations, and effects will become clear in the following description of the embodiments. [Brief explanation 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 3] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4A]1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4B] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4C] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4D] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4E] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4F] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4G] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4H] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4I] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4J] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4K] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4L] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4M] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 5] 1 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] 1 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] 1 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 the light source diffusion characteristics 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 the problem of irregular image light in a retroreflective module according to an embodiment of the present invention; [Figure 13B] 1 is a diagram illustrating the problem of irregular image light in a retroreflective module according to an embodiment of the present invention; [Figure 13C] FIG. 1 is an explanatory diagram illustrating the principle of a solution according to an embodiment of the present invention. [Figure 13D] FIG. 1 is an explanatory diagram illustrating the principle of a solution according to an embodiment of the present invention. [Figure 14A] 1 is a diagram illustrating a problem of irregular image light in a space floating image display device according to an embodiment of the present invention; [Figure 14B] 1 is a diagram illustrating a problem of irregular image light in a space floating image display device according to an embodiment of the present invention; [Figure 15A] 1 is a diagram showing an example (embodiment 1A) of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 15B] FIG. 1 is a diagram showing an example (embodiment 1B) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 15C] FIG. 1 is a diagram showing an example (embodiment 1C) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 15D] FIG. 1 is a diagram showing an example (embodiment 1D) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 16A] FIG. 10 is a diagram showing an example (embodiment 2A) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 16B] FIG. 10 is a diagram showing an example (embodiment 2B) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 16C] FIG. 10 is a diagram showing an example (embodiment 2C) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 16D] FIG. 10 is a diagram showing an example (embodiment 2D) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 17A] FIG. 10 is a diagram showing an example (embodiment 3A) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 17B] FIG. 10 is a diagram showing an example (embodiment 3B) of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 18A] FIG. 10 is a diagram showing a configuration of a holding unit in an example (embodiment 4A) of the configuration of the space floating image display device according to an embodiment of the present invention. [Figure 18B] FIG. 10 is a diagram showing a configuration of a holding member in an example (embodiment 4A) of the configuration of the space floating image display device according to an embodiment of the present invention. [Figure 18C] FIG. 10 is an explanatory diagram of the angle of arrangement of the holding members of the holding unit in an example of the configuration of the space floating image display device according to an embodiment of the present invention (embodiment 4A); [Figure 18D] FIG. 4B is a diagram showing a state in which a retroreflective module is arranged on one holding member of a holding unit in an example of the configuration of a space floating image display device according to an embodiment of the present invention (embodiment 4A). [Figure 18E] FIG. 4B is a diagram showing a state in which a retroreflective module is disposed on the other holding member of the holding unit in an example (Example 4A) of the configuration of the space floating image display device according to an embodiment of the present invention. [Figure 18F] FIG. 10 is a diagram showing a configuration of a screw hole of a holding unit in an example (embodiment 4A) of the configuration of the space floating image display device according to an embodiment of the present invention. [Figure 19A] FIG. 10 is a diagram showing a configuration of a holding unit in an example (embodiment 4B) of the configuration of the space floating image display device according to an embodiment of the present invention. [Figure 19B]FIG. 10 is a diagram showing a configuration of a holding unit in an example of the configuration of a space floating image display device according to an embodiment of the present invention (a modified example of embodiment 4B). DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the 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. Furthermore, in all drawings used to explain the present invention, components having the same functions are given the same reference numerals, and repeated explanations thereof may be omitted.

[0010] The following examples relate to an image display device that can transmit an image generated by image light from an image light source through a transparent member that separates a space, such as glass, and display the image as a floating image outside the transparent member. In the following explanation of the examples, the image floating in space is expressed using 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 displayed image," "floating optical image of displayed image," etc. The term "floating image in space," which is mainly used in the explanation of the examples, is used as a representative example of these terms.

[0011] According to the following embodiments, an image display device suitable for, for example, bank ATMs, train station ticket machines, digital signage, and the like can be realized. For example, currently, bank ATMs, train station ticket machines, and the like typically use touch panels. However, by using a transparent glass surface or a light-transmitting plate, high-resolution image information can be displayed in a floating state on the glass surface or light-transmitting plate. In this case, by making the divergence angle of the emitted image light small, i.e., an acute angle, and further aligning it with a specific polarization, only the normal reflected light is efficiently reflected by the retroreflector. This improves light utilization efficiency and suppresses the ghost images that occur in addition to the main floating image, which is a problem with conventional retroreflection systems, thereby achieving a clear floating image. Furthermore, by using a device including the light source of this embodiment, a novel and highly usable floating image display device (floating image display system) can be provided that can significantly reduce power consumption. Furthermore, a floating image display device for a vehicle can be provided that can display a so-called unidirectional floating image that can be viewed inside and / or outside the vehicle. Example 1

[0012] <Example of how to use the space floating image display device> 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 other figures. Light with a narrow-angle directional characteristic and specific polarization is emitted from image display device 1 as an image light beam, and after reflection by the optical system within the space-floating image display device, it first enters retroreflector 2, retroreflects, and passes through transparent member 100 (glass, etc.), forming a real aerial image (space-floating image 3) on the outside of the glass surface. In the following embodiments, 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 planar plate, but is used as an example of a concept including a sheet-like retroreflector attached to a planar or non-planar member, or an entire assembly in which a sheet-like retroreflector is attached to a planar or non-planar member such as resin or glass.

[0013] In addition, in a store or the like, a space is partitioned by a show window (also called "window glass") 105, which is a translucent member such as glass. According to the space floating image display device of this embodiment, it is possible to transmit such a transparent member and display a floating image 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 a means for reflecting specific polarized waves on the window glass 105, it is possible to reflect the waves and form an aerial image at a desired position inside the store.

[0015] <Configuration example of optical system for space floating image display device> 2A is a diagram showing an example of the configuration of an optical system of a space-floating image display device according to one embodiment of the present invention. The configuration of the space-floating image display device will be described in more detail using 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 an 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 with narrow-angle diffusion characteristics.

[0016] Image light of a specific polarization from the display device 1 is reflected by a polarization separator 101 (in the figure, the polarization separator 101 is formed into a sheet and adhered to the transparent member 100) that has a film that selectively reflects image light of a specific polarization and is provided on a transparent member 100, and then enters the retroreflector 2. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflector 2. The image light passes through the λ / 4 plate 21 twice, once when it enters the retroreflector 2 and once when it exits, thereby undergoing polarization conversion from the specific polarization to the other polarization. Here, the polarization separator 101 that selectively reflects image light of a specific polarization has the property of transmitting the polarized light of the other polarization that has been polarization-converted, so the image light of the specific polarization after polarization conversion passes through the polarization separator 101. The image light that has passed through the polarization separator 101 forms a space-floating image 3, which is a real image, outside the transparent member 100.

[0017] Here, a first example of polarization design for the optical system of FIG. 2A will be described. For example, S-polarized image light may be emitted from display device 1 to polarization separator 101, which may have the property of reflecting S-polarized light and transmitting P-polarized light. In this case, the S-polarized image light reaching polarization separator 101 from display device 1 is reflected by polarization separator 101 and travels toward retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, converting the image light from S-polarized light to P-polarized light. The P-polarized image light then travels back toward polarization separator 101. Here, polarization separator 101 has the property of reflecting S-polarized light and transmitting P-polarized light, so the P-polarized image light passes through polarization separator 101 and then through transparent member 100. The image light transmitted through the transparent member 100 is light 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 relative to the polarization separation member 101. This polarization design allows the floating image 3 to be formed optimally.

[0018] Next, a second example of polarization design for the optical system of FIG. 2A will be described. For example, a configuration may be adopted in which P-polarized image light is emitted from display device 1 to polarization separator 101, and polarization separator 101 has the property of reflecting P-polarized light and transmitting S-polarized light. In this case, the P-polarized image light that reaches polarization separator 101 from display device 1 is reflected by polarization separator 101 and travels toward retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, thereby converting the P-polarized image light to S-polarized light. The S-polarized image light then travels back toward polarization separator 101. Here, polarization separator 101 has the property of reflecting P-polarized light and transmitting S-polarized light, so the S-polarized image light passes through polarization separator 101 and then through transparent member 100. The image light transmitted through the transparent member 100 is light 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 relative to the polarization separation member 101. This polarization design allows the floating image 3 to be formed optimally.

[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 in a straight line even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is a highly directional image, unlike the diffused 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 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be perceived 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 directly facing the user.

[0020] Depending on the performance of the retroreflector 2, the polarization axis of the reflected image light may become irregular. The reflection angle may also become irregular. Such irregular light may not maintain the polarization state and propagation angle assumed in the design. For example, light with an unintended polarization state and propagation angle may re-enter the image display surface of the liquid crystal display panel 11 directly from the position of the retroreflector 2 without passing through a polarization separation member. Such light with an unintended polarization state and propagation angle may re-enter the image display surface of the liquid crystal display panel 11 after being reflected by components within the space-floating image display device. Such light re-entering the image display surface of the liquid crystal display panel 11 may be re-reflected by the image display surface of the liquid crystal display panel 11 constituting the display device 1, potentially generating ghost images and degrading the image quality of the space-floating image. Therefore, in this embodiment, an absorbing polarizer 12 may be provided on the image display surface of the display device 1. The image light emitted from the display device 1 is transmitted through the absorptive polarizer 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorptive polarizer 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 polarizer 12 may be a polarizer that absorbs P-polarized light. Furthermore, if the display device 1 is configured to emit P-polarized image light to the polarization separation member 101, the absorptive polarizer 12 may be a polarizer that absorbs S-polarized light.

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

[0022] Next, Figure 2A(2) shows the surface shape of a retroreflector manufactured by Nippon Carbide Industries Co., Ltd., which was used in this study as a representative retroreflector 2. Light rays incident on the regularly arranged hexagonal prisms are 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 diameter D and pitch P of the retroreflective portion of the retroreflector 2 shown in Figure 2A(2). For example, when using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective portion is 240 μm and the pitch is 300 μm, one pixel of the floating image in space will be equivalent to 300 μm. As a result, the effective resolution of the floating image in space will be reduced to about one-third.

[0024] Therefore, in order to make the resolution of the spatial floating image equivalent 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, to suppress the occurrence of moire caused by the retroreflective plate and the pixels of the liquid crystal display panel, it is advisable to design the pitch ratio of each to be a different integer multiple of one pixel. Also, it is advisable 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. Various surface shapes that achieve retroreflection may be used. Specifically, the surface of the retroreflector according to this embodiment may be provided with retroreflection elements in which triangular pyramidal prisms, hexagonal pyramidal prisms, other polygonal prisms, or a combination of these are periodically arranged. Alternatively, the surface of the retroreflector according to this embodiment may be provided with retroreflection elements in which these prisms are periodically arranged to form cube corners. Alternatively, the surface of the retroreflector according to this embodiment may be provided with capsule lens-type retroreflection elements in which glass beads are periodically arranged. The detailed configuration of these retroreflection elements can be achieved using existing technology, so a detailed description will be omitted. Specifically, the techniques disclosed in Japanese Patent 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 explained using Fig. 2B. In Fig. 2B, components with the same reference numerals as Fig. 2A have the same functions and configurations as Fig. 2A. For the sake of simplicity, repeated explanations of such components will be omitted.

[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 a polarization separator 101B. The polarization separator 101B is a member that selectively transmits image light of a specific polarization. Unlike the polarization separator 101 of FIG. 2A, the polarization separator 101B is not integrated with the transparent member 100 but has an independent plate-like shape. Therefore, the polarization separator 101B may also be referred to as a polarization separator plate. The polarization separator 101B may be configured as a reflective polarizer configured by attaching a polarization separator sheet to a transparent member. Alternatively, the transparent member may be formed of a metal multilayer film that selectively transmits specific polarization and reflects polarization of other specific polarizations. In FIG. 2B, the polarization separator 101B is configured to transmit image light of a specific polarization output from the display device 1.

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

[0029] Here, a first example of polarization design for the optical system of FIG. 2B will be described. For example, a configuration may be adopted in which P-polarized image light is emitted from display device 1 to polarization separator 101B, and polarization separator 101B has the property of reflecting S-polarized light and transmitting P-polarized light. In this case, the P-polarized image light that reaches polarization separator 101B from display device 1 passes through polarization separator 101B and proceeds to retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, thereby converting the P-polarized image light to S-polarized light. The S-polarized image light then proceeds again to polarization separator 101B. Here, polarization separator 101B has the property of reflecting S-polarized light and transmitting P-polarized light, so the S-polarized image light is reflected by polarization separator 101 and passes through transparent member 100. The image light transmitted through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a space-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 relative to the polarization separation member 101B. This polarization design allows the space-floating image 3 to be formed optimally.

[0030] Next, a second example of polarization design for the optical system of FIG. 2B will be described. For example, S-polarized image light may be emitted from display device 1 to polarization separator 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 polarization separator 101B from display device 1 passes through polarization separator 101B and proceeds to retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, converting the image light from S-polarized light to P-polarized light. The P-polarized image light then proceeds again to polarization separator 101B. Here, polarization separator 101B has the property of reflecting P-polarized light and transmitting S-polarized light, so the P-polarized image light is reflected by polarization separator 101 and passes through transparent member 100. The image light transmitted through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a space-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 relative to the polarization separation member 101B. This polarization design allows the space-floating image 3 to be formed optimally.

[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 separator 101B is arranged tilted at an angle α (e.g., 30°) relative to the image display surface of the display device 1 and the surface of the retroreflector 2. When the polarization separator 101B reflects the image light, the direction of the image light reflected by the polarization separator 101B (the direction of the chief ray of the image light) differs by an angle β (e.g., 60°) from the direction of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light). With this configuration, the optical system of FIG. 2B outputs the image light toward the outside of the transparent member 100 at a predetermined angle shown in the figure, forming the space-floating image 3, which is a real image. In the configuration of FIG. 2B , when a user views the space-floating image 3 from the direction of arrow A, the space-floating image 3 is perceived as a bright image. However, when another person views the space-floating image 3 from the direction of arrow B, the space-floating image 3 cannot be perceived 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 of FIG. 2B has a different configuration from the optical system of FIG. 2A, but can form a suitable floating image in space, similar to the optical system of FIG. 2A.

[0033] An absorptive polarizing plate may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. This absorptive polarizing plate may transmit the polarized waves of the image light from the polarization separation member 101B and absorb the polarized waves that are 90° out of phase with the polarized waves of the image light from the polarization separation member 101B. In this way, the image light for forming the space-floating image 3 can be sufficiently transmitted while reducing the external light incident on the space-floating image 3 side of the transparent member 100 by approximately 50%. This makes it possible to reduce stray light in the optical system of FIG. 2B due to the external light incident on 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 explained using Fig. 2C. In Fig. 2C, components with the same reference numerals as Fig. 2B have the same functions and configurations as Fig. 2B. For the sake of simplicity, such components will not be described repeatedly.

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

[0036] In the optical system of FIG. 2C , the polarization separator 101B is tilted 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, when the polarization separator 101B reflects, the angle β between the direction of propagation of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light) and the direction of propagation of the image light reflected by the polarization separator 101B (the 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 direction of propagation of the image light reflected by the polarization separator 101B, simplifying the angular relationships of the surfaces that make up the optical system. By arranging the surface of the transparent member 100 so that it is perpendicular to the direction of propagation of the image light reflected by the polarization separator 101B, the angular relationships of the surfaces that make up the optical system can be further simplified. In the configuration of Figure 2C, when a user views the floating image 3 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be seen as an image at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

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

[0038] An absorptive polarizer may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. This absorptive polarizer may transmit the polarized waves of the image light from the polarization separation member 101B and absorb the polarized waves that are 90° out of phase with the polarized waves of the image light from the polarization separation member 101B. This allows the image light for forming the space-floating image 3 to be sufficiently transmitted while reducing the external light incident on the space-floating image 3 side of the transparent member 100 by approximately 50%. This allows the stray light in the optical system of FIG. 2C due to the external light incident on the space-floating image 3 side of the transparent member 100 to be reduced.

[0039] According to the optical system of FIGS. 2A, 2B, and 2C described above, it is possible to provide a brighter, higher quality floating image in space.

[0040] <<Block diagram of the internal configuration of the space floating image display device>>

[0041] 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.

[0042] 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 supply 1106, an external power supply input interface 1111, an operation input unit 1107, a nonvolatile memory 1108, a memory 1109, a control unit 1110, a video signal input unit 1131, an audio signal input unit 1133, a communication unit 1132, an aerial operation detection sensor 1351, an aerial operation detection unit 1350, an audio output unit 1140, an image control unit 1160, a storage unit 1170, an imaging unit 1180, etc. In addition, the space-floating image display device 1000 may also 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.

[0043] Each component of the space floating image display device 1000 is disposed in a housing 1190. The imaging unit 1180 and the mid-air operation detection sensor 1351 shown in FIG.

[0044] The retroreflecting portion 1101 in Fig. 3 corresponds to the retroreflector 2 in Fig. 2A, Fig. 2B, and Fig. 2C. The retroreflecting portion 1101 retroreflects light modulated by the image display portion 1102. Of the light reflected from the retroreflecting portion 1101, the light output to the outside of the space-floating image display device 1000 forms the space-floating image 3.

[0045] 3 corresponds to the liquid crystal display panel 11 in FIGS. 2A, 2B, and 2C. The light source 1105 in FIG. 3 corresponds to the light source device 13 in FIGS. 2A, 2B, and 2C. The image display unit 1102, the light guide 1104, and the light source 1105 in FIG. 3 correspond to the display device 1 in FIGS. 2A, 2B, and 2C.

[0046] 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.

[0047] 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 AC current input from the outside via the external power input interface 1111 into DC current and supplies power to the light source 1105. The power source 1106 also supplies the necessary DC current to each unit within 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 via the external power input interface 1111 when power is not supplied from the outside. In other words, when the space-floating image display device 1000 is equipped with the secondary battery 1112, the user can use the space-floating image display device 1000 even when power is not supplied from the outside.

[0048] The light guide 1104 guides light generated by the light source 1105 and irradiates it onto the video display unit 1102. The combination of the light guide 1104 and the light source 1105 can also be called a backlight for the video display unit 1102. The light guide 1104 may be configured mainly using glass. The light guide 1104 may be configured mainly using plastic. The light guide 1104 may be configured using a mirror. There are various possible combinations 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.

[0049] The aerial operation detection sensor 1351 is a sensor that detects an operation on the floating in space image 3 by the finger of the user 230. The aerial operation detection sensor 1351 senses, for example, an area that overlaps with the entire display area of ​​the floating in space image 3. Note that the aerial operation detection sensor 1351 may only sense an area that overlaps with at least a portion of the display area of ​​the floating in space image 3.

[0050] Specific examples of the aerial operation detection sensor 1351 include a distance sensor that uses invisible light such as infrared light, an invisible laser, ultrasonic waves, etc. The aerial operation detection sensor 1351 may also be configured to detect coordinates on a two-dimensional plane by combining multiple sensors. The aerial operation detection sensor 1351 may also be configured with a ToF (Time of Flight) LiDAR (Light Detection and Ranging) or an image sensor.

[0051] The mid-air operation detection sensor 1351 only needs to be capable of sensing to detect touch operations, etc., made by the user with their finger on an object displayed as the floating-in-space image 3. Such sensing can be performed using existing technology.

[0052] The aerial operation detection unit 1350 acquires a sensing signal from the aerial operation detection sensor 1351, and based on the sensing signal, determines whether or not the finger of the user 230 has made contact with an object in the floating in space image 3, and calculates the position (contact position) where the finger of the user 230 has made contact with the object. The aerial operation detection unit 1350 is configured with a circuit such as an FPGA (Field Programmable Gate Array), for example. Furthermore, 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.

[0053] 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 as a separate entity from the space-floating image display device 1000. When provided as a separate entity from the space-floating image display device 1000, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 are configured to be able to transmit information and signals to the space-floating image display device 1000 via a wired or wireless communication connection path or a video signal transmission path.

[0054] 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 space-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 space-floating image display device 1000 may be used. In cases such as when it is desired to more freely position the aerial operation detection sensor 1351 relative to the installation position of the space-floating image display device 1000, a configuration in which only the aerial operation detection sensor 1351 is provided separately is advantageous.

[0055] The imaging unit 1180 is a camera with an image sensor, and captures images of 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 by using an imaging unit with a depth sensor, the mid-air operation detection unit 1350 can be assisted in detecting 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.

[0056] For example, if the aerial operation detection sensor 1351 is configured as an object intrusion sensor that targets a plane (intrusion detection plane) including the display surface of the spatial floating image 3 and detects whether or not an object has intruded into this intrusion detection plane, 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.

[0057] 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 from 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.

[0058] Furthermore, without using the mid-air operation detection sensor 1351, the mid-air operation detection unit 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 unit 1180.

[0059] Furthermore, the imaging unit 1180 may capture an image of the face of the user 230 operating the space-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 there is another person standing around or behind the user 230 operating the space-floating image 3 and peeking at the operation of the user 230 on the space-floating image 3, the imaging unit 1180 may capture an image of a range including the user 230 operating the space-floating image 3 and the surrounding area of ​​the user 230.

[0060] 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. Apart from the above-mentioned user 230 who touches the space floating image 3, the operation input unit 1107 may also be used by, for example, an administrator to operate the space floating image display device 1000.

[0061] The video signal input unit 1131 connects to an external video output device and inputs video data. The video signal input unit 1131 may be configured using various digital video input interfaces. For example, it may be configured using 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. Alternatively, an analog video input interface such as analog RGB or composite video may be provided. The audio signal input unit 1133 connects to an external audio output device and inputs audio data. The audio signal input unit 1133 may be configured using 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 HDMI standard interface, 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 using a speaker. The audio output unit 1140 may also 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.

[0062] The nonvolatile memory 1108 stores various data used by the space floating image display device 1000. The data stored in the nonvolatile memory 1108 includes, for example, data for various operations to be displayed on the space floating image 3, display icons, data and layout information for objects to be operated by user operations, etc. The memory 1109 stores image data to be displayed as the space floating image 3, data for controlling the device, etc.

[0063] The control unit 1110 controls the operation of each connected unit. In addition, the control unit 1110 may cooperate with a program stored in the memory 1109 to perform calculations based on information acquired from each unit in the space floating image display device 1000.

[0064] The communication unit 1132 communicates with external devices, external servers, etc. via a wired or wireless communication interface. If the communication unit 1132 has a wired communication interface, the wired communication interface may be configured, for example, as an Ethernet LAN interface. If the communication unit 1132 has a wireless communication interface, the interface may be configured, for example, as a Wi-Fi communication interface, a Bluetooth communication interface, or a mobile communication interface such as 4G or 5G. Various types of data, such as video data, image data, and audio data, are transmitted and received through communication via the communication unit 1132.

[0065] Furthermore, 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 device 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 can read various information such as video data, image data, and audio data recorded on the removable recording medium. The video data, image data, etc. recorded on the removable recording medium are output as the floating image 3 via the video display unit 1102 and the retroreflection unit 1101.

[0066] The storage unit 1170 is a storage device that records various types of information such as video data, image data, audio data, etc. 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 types of information such as video data, image data, audio data, etc. may be recorded in advance in the storage unit 1170 at the time of product shipment. Furthermore, the storage unit 1170 may record various types of information such as video data, image data, audio data, etc. acquired from an external device, an external server, etc. via the communication unit 1132.

[0067] 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, etc., displayed as the space floating image 3, are also recorded in the storage unit 1170.

[0068] Layout information of display icons, objects, etc. displayed as the space floating image 3, and various metadata information related to the objects, etc. 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.

[0069] 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, FPGA, or 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 controls video switching, such as 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.

[0070] In addition, the video control unit 1160 may generate a superimposed video signal by superimposing the video signal to be stored in the memory 1109 and the video signal input from the video signal input unit 1131, and input the superimposed video signal to the video display unit 1102, thereby performing control to form the composite video as the floating-in-space video 3.

[0071] 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 to enlarge, reduce, deform, etc. the image, brightness adjustment processing to change the brightness, contrast adjustment processing to change the contrast curve of the image, and Retinex processing to decompose the image into light components and change the weighting of each component.

[0072] Furthermore, the video control unit 1160 may perform special effect video processing or the like to assist 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 based on, for example, the detection result of the touch operation of the user 230 by the aerial operation detection unit 1350 and the image of the user 230 captured by the imaging unit 1180.

[0073] The attitude sensor 1113 is a sensor configured by a gravity sensor or 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 in the user's usage state is detected, the control unit 1110 may perform control such that the image being displayed on the image display unit 1102 is stopped and an error message is displayed to the user. Alternatively, when the attitude sensor 1113 detects a change in the installation attitude of the space-floating image display device 1000, the control unit 1110 may perform control such that the display direction of the image being displayed on the image display unit 1102 is rotated.

[0074] 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 any configuration is acceptable as long as it has the function of forming the space-floating image 3.

[0075] <Configuration example of a space floating image display device> Next, a configuration example of the space-floating image display device will be explained. The layout of the components of the space-floating image display device according to this embodiment can be various depending on the usage form. Below, the layouts of each of Figs. 4A to 4M will be explained. In addition, in each example of Figs. 4A to 4M, the thick line surrounding the space-floating image display device 1000 indicates an example of the housing structure of the space-floating image display device 1000.

[0076] 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 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 installed as shown in the figure, it can 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 explanations will be omitted.

[0077] 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 (toward the user 230). That is, in FIG. 4B, the space-floating image display device is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 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 diagonally upward. 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. 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 reflectivity of the nail is higher than that of the finger pad, so this configuration can improve the accuracy of touch detection.

[0078] 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 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. 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 user's 230 finger.

[0079] 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 (toward the user 230). That is, in FIG. 4D, the space-floating image display device 1000 is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 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 diagonally upward. 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 user 230's finger. 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 reflectivity of the nail is higher than that of the finger pad, so this configuration can improve the accuracy of touch detection.

[0080] 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 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 directly upward. 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.

[0081] 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 (toward the user 230). That is, in FIG. 4F, the space-floating image display device 1000 is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 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 user 230's finger.

[0082] 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 shown in FIG. 2C. In the optical systems of the space-floating image display devices shown in FIGS. 4A to 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 systems of the space-floating image display devices shown in FIGS. 4A to 4F, the image light traveled in the front-to-back and up-to-down directions 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-to-right and front-to-back directions as seen from the user. The space-floating image display device 1000 shown in FIG. 4G is installed so that the surface on which the space-floating image 3 is formed faces the front of the device (toward 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 towards the user. If the mid-air operation detection sensor 1351 is installed as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0083] 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 differs from the space-floating image display device of FIG. 4G in that it has a window with a transparent plate 100B made of glass or plastic on the back of the device (opposite the position 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 rest of the configuration is the same as that 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 with a transparent plate 100B on the opposite side of the traveling direction of the image light of the space-floating image 3 from the space-floating image 3. Therefore, when the user 230 views the space-floating image 3, they 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 perceive 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 the space floating image 3 floating in the air.

[0084] Depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separator 101B, a portion of the image light output from the display device 1 may be reflected by the polarization separator 101B and head 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 be visible to the user as stray light. Therefore, in order to prevent this stray light, the transparent plate 100B may not be provided in the window on the back of the space-floating image display device 1000.

[0085] 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 of FIG. 4I differs from the space-floating image display device of FIG. 4H in that a light-blocking door 1410 is provided at the window of a transparent plate 100B located on the back of the device (the opposite side from where the user 230 views the space-floating image 3). Other configurations are the same as those of the space-floating image display device of FIG. 4H , so repeated explanations will be omitted. The door 1410 of the space-floating image display device 1000 of FIG. 4I has, for example, a light-blocking plate and a mechanism for moving (sliding), rotating, or attaching / detaching the light-blocking plate, thereby switching between an open state and a light-blocking state for the window of the transparent plate 100B located at the back of the space-floating image display device 1000 (the rear window). The movement (sliding) and rotation of the light-blocking plate by the door 1410 may be electrically driven by a motor (not shown). The motor may be controlled by the control unit 1110 of FIG. 3. 4I shows an example in which the number of light-shielding plates in the opening and closing door 1410 is two. However, the number of light-shielding plates in the opening and closing door 1410 may be one.

[0086] For example, when the view 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 outdoor sunlight is strong, the background of the space-floating image 3 may become too bright, reducing the user 230's visibility of the space-floating image 3. In such a case, by moving (sliding), rotating, or attaching the light blocking plate of the opening / closing door 1410 to block the light from the rear window, the background of the space-floating image 3 becomes dark, thereby relatively increasing the visibility of the space-floating image 3. Such a blocking operation by the light blocking plate of the opening / closing door 1410 may be performed directly by the force of the user 230's hand. 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 the blocking operation by the light blocking plate of the opening / closing door 1410.

[0087] An illuminance sensor may be provided on the rear side (opposite 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 of Fig. 3 may control a motor (not shown) to perform the opening and closing operation of the light blocking 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 blocking plate of the opening and closing door 1410 in this way, it becomes 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 blocking plate of the opening and closing door 1410.

[0088] Furthermore, the light blocking plate by the opening and closing door 1410 may be manually detachable. Depending on the intended use and installation environment of the space floating image display device 1000, the user can select whether to leave the rear window open or in a light blocking state. If it is planned to use the rear window in a light blocking state for a long period of time, the detachable light blocking plate can be fixed in the light blocking state. Also, if it is planned to use the rear window in an open state for a long period of time, it can be used with the detachable light blocking plate removed. The light blocking plate may be attached and detached using screws, a hook structure, or a fitting structure.

[0089] Even in the example of the space-floating image display device 1000 shown in FIG. 4I, depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separator 101B, a portion of the image light output from the display device 1 may be reflected by the polarization separator 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 be perceived by the user as stray light. Therefore, to prevent this stray light, the window on the back of the space-floating image display device 1000 may be configured without the transparent plate 100B. The above-described opening / closing door 1410 may be provided in a window that does not have the transparent plate 100B. To prevent this stray light, it is desirable that the inner surface of the housing of the light-shielding plate of the above-described opening / closing door 1410 have a coating or material with low light reflectance.

[0090] 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 differs from the space-floating image display device of FIG. 4H in that instead of the transparent plate 100B made of glass or plastic, an electronically controlled transmittance variable device 1620 is provided on the rear window. The other components are the same as those of the space-floating image display device of FIG. 4H, and therefore will not be described again. An example of the electronically controlled transmittance variable device 1620 is a liquid crystal shutter. That is, a liquid crystal shutter can control the transmitted light by controlling the voltage of a liquid crystal element sandwiched between two polarizing plates. Therefore, by controlling the liquid crystal shutter to increase the transmittance, the background of the space-floating image 3 can be seen through the scenery through the rear window. Furthermore, by controlling the liquid crystal shutter to increase the transmittance, the scenery through the rear window can be hidden as the background of the space-floating image 3. Furthermore, since the liquid crystal shutter can be controlled to an intermediate length, it can also be set to a transmittance of 50%, for example. For example, the control unit 1110 may control the transmittance of the electronically controlled transmittance varying device 1620 in response to an operation input via the operation input unit 1107 in Fig. 3. With this configuration, in cases where a viewer wants to see the scenery through the rear window as the background of the Space Floating Image 3, but the scenery through the rear window as the background is too bright and reduces the visibility of the Space Floating Image 3, the visibility of the Space Floating Image 3 can be adjusted by adjusting the transmittance of the electronically controlled transmittance varying device 1620.

[0091] In addition, an illuminance sensor may be provided on the back side (opposite 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 controls 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 rear window, making it possible to more suitably maintain the visibility of the space-floating image 3.

[0092] In the above example, a liquid crystal shutter has been described as an example of the electronically controlled variable transmittance device 1620. However, electronic paper may be used as another example of the electronically controlled variable transmittance device 1620. The same effects as those 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 lower power consumption can be realized compared to when a liquid crystal shutter is used.

[0093] 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 differs 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.

[0094] In the space-floating image display device 1000 of FIG. 4K, a light beam of an image passes through the display surface of the transmissive self-luminous image display device 1650, and then a 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-up image further in front of the image displayed on the transmissive self-luminous image display device 1650. In this case, 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, Japanese Patent Application Laid-Open No. 2014-216761. Although not shown in FIG. 3, the transmissive self-luminous image display device 1650 may be configured as a component of the space-floating image display device 1000 of FIG. 3 and connected to other processing units such as the control unit 1110.

[0095] Here, if the transmissive self-luminous video display device 1650 displays both the background and an object such as a character, and then the object such as the character moves to the foreground, the floating video image 3, a more effective surprise video experience can be provided to the user 230.

[0096] Furthermore, if the inside of the space-floating image display device 1000 is kept in a light-blocking state, the background of the transmissive self-luminous image display device 1650 becomes sufficiently dark. Therefore, when no image is displayed on the display device 1 or the light source of the display device 1 is turned off and an image is displayed only on the transmissive self-luminous image display device 1650, the transmissive self-luminous image display device 1650 appears to the user 230 as a normal two-dimensional flat display rather than a transmissive display (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 empty space). Therefore, when the transmissive self-luminous image display device 1650 is used to display an image as if it were a normal two-dimensional flat display, characters, objects, etc. can be suddenly displayed in the air as the space-floating image 3, thereby providing the user 230 with a more effective surprise video experience.

[0097] Note that the darker the interior of the space-floating image display device 1000, the more the transmissive self-luminous image display device 1650 appears like a two-dimensional flat display. Therefore, an absorptive polarizer (not shown) that transmits the polarized waves of the image light reflected by the polarization separation member 101B and absorbs polarized waves that are 90° out of phase with the polarized waves may be provided on the surface of the transmissive self-luminous image display device 1650 facing the interior of the space-floating image display device 1000 (the surface where the image light reflected by the polarization separation member 101B enters the transmissive self-luminous image display device 1650, i.e., the surface of the transmissive self-luminous image display device 1650 opposite the space-floating image 3). This does not have a significant effect on the image light that forms the space-floating image 3, but it can significantly reduce the light that enters the interior of the space-floating image display device 1000 from the outside through the transmissive self-luminous image display device 1650, making the interior of the space-floating image display device 1000 darker, which is preferable.

[0098] 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 arrangement of 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.

[0099] In the space-floating image display device of FIG. 4L, after the 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.

[0100] In both 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, 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 their head (the position of the viewpoint), they can recognize the depth of the two images due to parallax. Therefore, by displaying two images at different depth positions, it is possible to provide the user with a more suitable three-dimensional image experience with the naked eye without the need for stereoscopic glasses or the like.

[0101] Fig. 4M is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device of Fig. 4M has a second display device 1680 provided on the rear side, as seen from the user, of the polarization separation member 101B of the space-floating image display device of Fig. 4G. The other configurations are the same as those of the space-floating image display device of Fig. 4G, so repeated explanations will be omitted.

[0102] 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 its image display surface faces the space-floating image 3. With this configuration, from the user 230's perspective, 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 superimposed on each other. In other words, the second display device 1680 is positioned so as to display an image in the direction of the user 230 viewing 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.

[0103] Note that the image light of the second display device 1680 of the space-floating image display device 1000 of FIG. 4M is viewed by the user 230 after passing through the polarization separator 101B. Therefore, in order for the image light of the second display device 1680 to more suitably pass through the polarization separator 101B, it is desirable that the image light output from the second display device 1680 be polarized in a vibration direction that the polarization separator 101B more suitably transmits. That is, it is desirable that the image light be polarized in the same vibration direction as the polarization of the image light output from the display device 1. For example, if the image light output from the display device 1 is S-polarized, it is desirable that the image light output from the second display device 1680 is also S-polarized. Furthermore, if the image light output from the display device 1 is P-polarized, it is desirable that the image light output from the second display device 1680 is also P-polarized.

[0104] 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 a 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 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, but may be a liquid crystal display, which is a two-dimensional flat display. The second display device 1680 may also be an organic EL display. Therefore, the example of the space-floating image display device of FIG. 4M can 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.

[0105] 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 portion 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 portion 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.

[0106] Therefore, to prevent this stray light, an absorptive polarizer may be provided on the surface of the second display device 1680. In this case, the absorptive polarizer may be an absorptive polarizer that transmits the polarized waves of the image light output from the second display device 1680 and absorbs polarized waves that are 90° out of phase with the polarized waves of the image light output from the second display device 1680. If the second display device 1680 is a liquid crystal display, an absorptive polarizer is also provided on the image output side of 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 polarizer on the image output side of the liquid crystal display, it is not possible to prevent stray light caused by reflection of the cover glass by light from outside the liquid crystal display. Therefore, it is necessary to separately provide the above-mentioned absorptive polarizer on the surface of the cover glass.

[0107] 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 further in front of the image on the second display device 1680. In this case, the user 230 can simultaneously view two images at different depth positions. By displaying a character on the floating-in-space image 3 and a background on the second display device 1680, it is possible to provide the effect that the user 230 is viewing the space in which the character exists in a three-dimensional manner.

[0108] 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 in the floating image 3, it is possible to provide the user 230 with a more effective surprise visual experience.

[0109] <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 11 (liquid crystal display panel) and a light source device 13 that constitutes its light source. Fig. 5 shows the light source device 13 together with the liquid crystal display panel as an exploded perspective view.

[0110] As shown by arrow 30 in Figure 5, this liquid crystal display panel (image display element 11) receives an illumination light beam from 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 retroreflector 2 and passes through transparent member 100 to form a real image, a floating image in space (see Figure 1).

[0111] 5 also shows a configuration including a liquid crystal display panel 11 constituting the display device 1, a light redirection panel 54 that controls the directional characteristics of the light beam emitted from the light source device 13, and a narrow-angle diffuser (not shown) as needed. Specifically, polarizing plates are provided on both sides of the liquid crystal display panel 11, and image light of a specific polarization is emitted with its intensity modulated by a video signal (see arrow 30 in FIG. 5). This allows a desired image to be projected as highly directional (linearly propagating) light of a specific polarization via the light redirection panel 54 toward the retroreflector 2. After being reflected by the retroreflector 2, the light is transmitted toward the eyes of an observer outside the store (space), forming a floating image 3. A protective cover 50 (see FIGS. 6 and 7) may be provided on the surface of the light redirection panel 54.

[0112] <Display device example 1> FIG. 6 shows an example of a specific configuration of the display device 1. In FIG. 6, a liquid crystal display panel 11 and a light direction conversion panel 54 are disposed on the light source device 13 shown in FIG. 5. The light source device 13 is configured on a case shown in FIG. 5, which is formed of, for example, plastic and contains LED elements 201 and a light guide 203. As shown in FIG. 5 and other figures, the end surface of the light guide 203 is provided with a lens shape whose cross-sectional area gradually increases toward the light receiving section in order to convert the divergent light from each LED element 201 into a substantially parallel beam. The lens shape has an effect of gradually reducing the divergence angle by multiple total reflections during propagation within the light guide 203. The liquid crystal display panel 11 constituting the display device 1 is attached to the top surface of the display device 1. In addition, LED (Light Emitting Diode) elements 201, which are semiconductor light sources, and an LED board 202 on which their control circuits are mounted are attached to one side surface (the left end surface in this example) of the case of the light source device 13. 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.

[0113] The liquid crystal display panel frame (not shown) is attached to the top surface of the case of the light source device 13. The liquid crystal display panel 11 is attached to the frame, and an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11 is also attached to the frame. That is, the liquid crystal display panel 11, which is the image display element, generates a display image by modulating the intensity of transmitted light in conjunction with the LED elements 201, which are solid-state light sources, based on a control signal from a control circuit (image control unit 1160 in FIG. 3) constituting the electronic device. The generated image light has a narrow diffusion angle and contains only specific polarization components, resulting in a novel image display device similar to a surface-emitting laser image source driven by a video signal. Currently, it is technically and safety-wise impossible to obtain a laser beam of the same size as the image obtained by the display device 1 described above using a laser device. Therefore, in this embodiment, light similar to the surface-emitting laser image light described above is obtained from a beam of light from a general light source, for example, an LED element.

[0114] Next, the configuration of the optical system housed in the case of the light source device 13 will be described in detail with reference to FIG. 7 as well as FIG.

[0115] 6 and 7 are cross-sectional views, and only one of the multiple LED elements 201 constituting the light source is shown, and this light 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 portion of the light guide end surface and the LED element are attached while maintaining a predetermined positional relationship.

[0116] Each light guide 203 is formed of a translucent resin such as acrylic. The LED light receiving surface at the end of light guide 203 has a cone-shaped outer periphery obtained by rotating a parabolic cross section, and at the top of the light guide 203, a concave portion with 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 (or a concave lens surface) that protrudes outward (not shown). The outer shape of the light receiving portion of the light guide to which LED element 201 is attached is a parabolic shape that forms a cone-shaped outer periphery, and is set within an angle range that allows total reflection within the light that is emitted from the LED element toward the periphery, or a reflective surface is formed.

[0117] 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 to the LED collimator (light-receiving end surface 203a) so that the LED elements 201 on the surface are positioned in the center of the recessed portion described above.

[0118] According to this configuration, the shape of the light-receiving end surface 203a of the light guide 203 makes it possible to extract the light emitted from the LED element 201 as approximately parallel light, thereby improving the efficiency of use of the generated light.

[0119] As described above, the light source device 13 is configured by attaching a light source unit in which a plurality of LED elements 201 serving as light sources are arranged to the light-receiving end surface 203a, which is a light-receiving section provided on the end surface of the light guide 203, and the divergent light beams from the LED elements 201 are converted into approximately parallel light by the lens shape of the light-receiving end surface 203a of the light guide end surface, which is then guided inside the light guide 203 (in a direction parallel to the drawing) as shown by the arrow, and emitted by the light beam direction conversion means 204 toward the liquid crystal display panel 11, which is disposed approximately parallel to the light guide 203 (in a direction perpendicular to the front 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 inside or on the surface of the light guide.

[0120] 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 (in a direction perpendicular to the front of the drawing) which is disposed substantially parallel to the light guide 203, by changing the shape of the surface of the light guide or by providing a portion with a different refractive index inside the light guide. In this case, when the liquid crystal display panel 11 is faced directly at the center of the screen and the viewpoint is positioned at the same position as the diagonal dimension of the screen, if the relative brightness ratio between the center of the screen and the periphery of the screen is 20% or more, there is no practical problem, and if it exceeds 30%, it will be an even better characteristic.

[0121] 6 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including 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 having 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 of light source device 13 is attached liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0122] In addition, a film- or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (bottom surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, selectively reflecting one polarization (e.g., P-wave) 212 of the natural light beam 210 emitted from the LED element 201. The reflected light is reflected again by a reflective sheet 205 provided on one surface (bottom 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 reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49. The reflected light beam is reflected by the reflective sheet 205 and passes through it twice, converting the reflected light beam from P-polarized to S-polarized, thereby improving the utilization efficiency of the light source light as image light. The image light beam, the light intensity of which is modulated by a video signal in the liquid crystal display panel 11 (arrow 213 in Figure 6), enters the retroreflector 2. After reflection by the retroreflector 2, a real, floating image can be obtained.

[0123] 7 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED elements 201, similar to Fig. 6. Light source device 13 is similarly composed of light guide 203 formed of, for example, plastic and having light beam direction conversion means 204 on its surface or inside, LED elements 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc. On the top surface of light source device 13, a liquid crystal display panel 11 is attached as an image display element, which has polarizing plates on the light source light entrance surface and the image light exit surface.

[0124] A film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (bottom surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, selectively reflecting one polarized wave (e.g., S wave) 211 of the natural light beam 210 emitted from the LED element 201. In other words, the selective reflection characteristics of the reflective polarizing plate 49 in the example of FIG. 7 differ from those in FIG. 7. The reflected light is reflected by a reflective sheet 205 provided on one surface (bottom surface in the figure) of the light guide 203 and returns to 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, converting it from S-polarized light to P-polarized light, thereby 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.

[0125] In the light source devices shown in Figures 6 and 7, in addition to the function of the polarizer provided on the light incident surface of the corresponding liquid crystal display panel 11, the reflective polarizer reflects the polarized light component on one side, so the theoretically obtainable contrast ratio is the reciprocal of the cross transmittance of the reflective polarizer multiplied by the reciprocal of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel. This results in high contrast performance. In fact, experiments have confirmed that the contrast performance of the displayed image is improved by more than 10 times. As a result, high-quality images comparable to those of self-luminous organic EL displays are obtained.

[0126] <Display device example 2> 8 shows another example of the specific configuration of the display device 1. This light source device 13 is configured by housing LEDs, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and has a liquid crystal display panel 11 attached to its upper surface. Also, an LED board on which LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and their control circuits are mounted is attached to one side of the case of light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer surface of the LED board.

[0127] The liquid crystal display panel frame attached to the top surface of the case is configured to have attached thereto a liquid crystal display panel 11 attached to the frame, and further to have attached thereto an FPC (Flexible Printed Circuits) 403 electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light together with the LED elements 14a and 14b, which are solid-state light sources, based on a control signal from a control circuit (not shown here) that constitutes the electronic device.

[0128] <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 a divergent beam of light (a mixture of P-polarized and S-polarized light) from an LED into a substantially parallel beam by a collimator 18, and reflects the parallel beam toward the liquid crystal display panel 11 by the reflecting surface of a reflective light guide 304. The reflected light is incident on a reflective polarizer 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. The reflective polarizer 49 transmits light of a specific polarization (e.g., P-polarized light) and causes the transmitted polarized light to be incident on the liquid crystal display panel 11. Here, light of polarization other than the specific polarization (e.g., S-polarized light) is reflected by the reflective polarizer 49 and directed toward the reflective light guide 304 again.

[0129] The reflective polarizing plate 49 is installed at an angle with respect to the liquid crystal display panel 11 so that the reflective polarizing plate 49 is not perpendicular to the chief ray of light from the reflective surface of the reflective light guide 304. The chief ray of the light reflected by the reflective polarizing plate 49 is incident on the transmission surface of the reflective light guide 304. The light that has entered the transmission surface of the reflective light guide 304 passes through the back surface of the reflective light guide 304, passes through the λ / 4 plate 270 which is a retardation plate, and is reflected by the reflector 271. The light reflected by the reflector 271 passes through the λ / 4 plate 270 again, and passes through the transmission surface of the reflective light guide 304. The light that has passed through the transmission surface of the reflective light guide 304 is incident on the reflective polarizing plate 49 again.

[0130] At this time, the light that re-enters the reflective polarizer 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarization (for example, P-polarized light) that is transmitted through the reflective polarizer 49. Therefore, the light whose polarization has been converted passes through the reflective polarizer 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 in reverse from the above explanation (S-polarized light and P-polarized light may be reversed).

[0131] As a result, the light from the LED is aligned to a specific polarization (for example, P polarization), enters the liquid crystal display panel 11, and is brightness-modulated in accordance with 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, since this is a vertical cross section, only one is shown in Figure 9), and these are attached at predetermined positions relative to the collimator 18.

[0132] Each of the collimators 18 is formed of, for example, a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer peripheral surface obtained by rotating a parabolic cross section. The collimator 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 collimator 18 may have a convex lens surface (or a concave lens surface) protruding outward in the center of the flat portion (the side opposite the apex). The parabolic surface forming the cone-shaped outer peripheral surface of the collimator 18 is set within an angle range that allows total reflection of the light emitted from the LED toward the periphery within the parabolic surface, or a reflective surface is formed therein.

[0133] The LEDs are arranged at predetermined positions on the surface of the circuit board, that is, the LED substrate 102. The LED substrate 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface are positioned at the center of the apex of the convex cone shape (or in the recess if there is a recess at the apex).

[0134] With this configuration, the collimator 18 focuses the light emitted from the LED, particularly the light emitted from the central portion, into parallel light by the convex lens surface that forms the outer shape of the collimator 18. Light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the conical shape of the collimator 18, and is similarly focused into parallel light. In other words, the collimator 18, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract almost all of the light generated by the LED as parallel light, thereby improving the utilization efficiency of the generated light.

[0135] Furthermore, the light converted into approximately parallel light by the collimator 18 shown in FIG. 9 is reflected by the reflective light guide 304. Due to the action of the reflective polarizer 49, light of a specific polarization of the light is transmitted through the reflective polarizer 49, while light of the other polarization reflected by the reflective polarizer 49 is transmitted again through the light guide 304. The light is reflected by the reflector 271, which is 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 twice by passing through the λ / 4 plate 270, which is a retardation plate. The light reflected by the reflector 271 is transmitted again through the light guide 304 and enters the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarization-converted, it is transmitted through the reflective polarizer 49 and enters the liquid crystal display panel 11 with its polarization direction aligned. As a result, all of the light from the light source can be utilized, thereby doubling the geometrical optical utilization efficiency of light. Furthermore, 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. Adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 allows adjustment of the angle of light reflection and diffusion at each reflective surface. 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 to optimize the uniformity of the light incident on the liquid crystal display panel 11.

[0136] 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 incident angle distribution of the polarized light.

[0137] <Display device example 4> Furthermore, another example (Example 4 of Display Device) of the configuration of an optical system such as a light source device of a display device will be described with reference to Fig. 10. This is an example of a configuration in which a diffusion sheet is used instead of reflective light guide 304 in the light source device of Example 3 of the display device. Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) that convert the diffusion characteristics in the vertical and horizontal directions of the drawing (front-to-back directions not shown in the drawing) are used on the light emission side of collimator 18, and light from collimator 18 is made to enter between the two optical sheets (diffusion sheets).

[0138] The optical sheet may be a single sheet instead of a two-sheet configuration. In the case of a single sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes on the front and back surfaces of the single optical sheet. Alternatively, multiple diffusion sheets may be used to share the functions. In the example of FIG. 10, the reflection and diffusion characteristics due to the front and back shapes of optical sheets 207A and 207B can be optimally designed using the number of LEDs, the divergence angle from LED substrate (optical element) 102, and the optical specifications of collimator 18 as design parameters so that the surface density of the light beam emitted from liquid crystal display panel 11 is uniform. In other words, the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of light guides.

[0139] In the example of FIG. 10, 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, reflective polarizing plate 49 may be configured to have the 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 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 retardation plate 270 shown in FIG. 10. The light that passes through retardation plate 270 is reflected by reflector 271. The light reflected by reflector 271 passes through retardation plate 270 again and is converted to P-polarized light. The polarization-converted light passes through reflective polarizing plate 49 and enters liquid crystal display panel 11.

[0140] It should be noted that the λ / 4 plate 270, which is the retarder in FIG. 10, 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. 10, any retarder that changes the phase by 90° (λ / 2) when polarized light passes through it twice will suffice. The thickness of the retarder may be adjusted according to the distribution of incident angles of the polarized light. It should be noted that in FIG. 10 as well, the polarization design for polarization conversion may be configured in reverse (reversing the S-polarized light and P-polarized light) from the above explanation.

[0141] In a typical TV device, the light emitted from the LCD panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown on the X-axis in FIG. 12(a)) and the vertical direction of the screen (shown on the Y-axis in FIG. 12(b)). In contrast, the diffusion characteristics of the light beam emitted from the LCD panel of this embodiment are 1 / 5 of the 62-degree viewing angle of a typical TV device, as shown in Example 1 of FIG. 12, when the viewing angle at which the luminance is 50% of that at a front view (angle of 0 degrees) is set to 13 degrees. Similarly, the vertical viewing angle is asymmetric between the top and bottom, and the reflection angle and the area of ​​the reflective surface of the reflective light guide are optimized to keep the upper viewing angle to about 1 / 3 of the lower viewing angle. As a result, the amount of image light directed toward the monitoring direction is significantly improved compared to conventional LCD TVs, with brightness more than 50 times higher.

[0142] Furthermore, assuming the viewing angle characteristics shown in Example 2 in Figure 12, if the viewing angle at which brightness is 50% of that when viewed from the front (angle of 0 degrees) is set to 5 degrees, this will be 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 and the area of ​​the reflective surface of the reflective light guide so that the viewing angle is approximately 1 / 12 of that of devices used for general TV applications, with equal viewing angle both above and below. As a result, the amount of image light directed in the monitoring direction is significantly improved compared to conventional LCD TVs, and brightness is more than 100 times greater.

[0143] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux directed in the monitoring direction can be concentrated, significantly improving the efficiency of light utilization. As a result, even when using a liquid crystal display panel for general TV applications, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create a video display device that is compatible with information display systems facing bright outdoor environments.

[0144] When using a large LCD display panel, the overall brightness of the screen can be improved by directing the light from the periphery of the screen inward so that it is directed toward the observer when the observer is facing the center of the screen. Figure 11 shows the convergence angle between 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 in portrait orientation, the convergence angle can be set to match the short side. For example, when using a 22" panel in portrait orientation and the monitoring distance is 0.8m, 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.

[0145] Similarly, when monitoring with a 15" panel in portrait orientation and the monitoring distance is 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 towards the monitor. 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 towards the monitor who is in the optimum position to monitor the centre of the screen.

[0146] As shown in Figure 9, the basic configuration involves a light source device directing a light beam with a narrow angle of directionality to a liquid crystal display panel 11, which is then luminance-modulated according to a video signal. The video information displayed on the screen of the liquid crystal display panel 11 is then reflected by a retroreflector, and the resulting floating image is displayed indoors or outdoors via a transparent member 100.

[0147] By using the display device and light source device according to the embodiment of the present invention described above, it is possible to realize a space floating image display device with higher light utilization efficiency.

[0148] <Embodiment of the Floating Image Display Device> Next, we will explain a floating-in-the-air image display device of an embodiment. The following embodiment shows a configuration that can reduce the effect of ghost images caused by a λ / 4 plate in a retroreflective member. The floating-in-the-air image display device of this embodiment includes an image display device including a liquid crystal display panel and a light source device; a polarization separation member that reflects image light of a specific polarization from the image display device and transmits image light of the other polarization; a retroreflective module having a λ / 4 plate and a retroreflective member that retroreflects the image light of the specific polarization from the polarization separation member and converts it into image light of the other polarization; and a housing that holds the image display device, the polarization separation member, and the retroreflective module. The polarization separation member transmits the image light of the other polarization from the retroreflective module, forming a floating-in-the-air image, which is a real image, at a predetermined position outside the housing. Furthermore, a first angle formed by the image display device with respect to the polarization separation member and a second angle formed by the retroreflective module with respect to the polarization separation member are different from the first angle. For example, the second angle is greater than the first angle, or the second angle is less than the first angle.

[0149] <Issues of ghost images caused by λ / 4 plates> Using Figure 13A and other figures, we will explain the problem of ghost images caused by the λ / 4 plate of the retroreflective member. Figure 13A is an explanatory diagram of the problem of ghost images caused by the λ / 4 plate of the retroreflective member. Figure 13A shows a schematic cross-sectional view (a two-dimensional diagram of a three-dimensional shape) of a retroreflective module 200 having a retroreflective member 2 and a λ / 4 plate 21 provided on its retroreflective surface (surface). The retroreflective surface 2A of the retroreflective member 2 has a surface shape, for example, a triangular shape, as shown in the figure. The λ / 4 plate 21 is bonded and fixed to the retroreflective surface 2A of the retroreflective member 2 via a sealing resin 22. Incident light 13A1 from the polarization separation member 101 described above is emitted from the retroreflective surface 2A in the opposite direction as retroreflected light 13A2 due to the surface shape of the retroreflective surface 2A.

[0150] Here, a portion of the light incident on the retroreflective surface 2A of the retroreflective member 2 (incident light 13A3) is specularly reflected by the surface of the λ / 4 plate 21, etc., and is emitted as specularly reflected light, i.e., irregular image light 13A4. In addition to the surface of the λ / 4 plate 21, specularly reflected light may also be generated by the interface between the sealing resin 22 and the λ / 4 plate 21 in the retroreflective module 200, etc.

[0151] If the retroreflected light 13A2 that forms the floating-in-the-air image 3 is considered to be normal image light, the specularly reflected light 13A4 generated by the λ / 4 plate 21 is abnormal image light that forms a ghost image of the normal image light. This abnormal image light 13A4 appears as a ghost image when a user views the floating-in-the-air image 3, reducing visibility. Therefore, reducing this abnormal image light 13A4 is an issue.

[0152] 13B is a schematic explanatory diagram illustrating the generation of a ghost image due to the irregular image light (specularly reflected light) 13A4 in FIG. 13A. The irregular image light 13A4 generated by the retroreflection module 200 including the λ / 4 plate 21 becomes a ghost image 13B1 for the floating-in-the-air image 3. This ghost image 13B1 is formed as a virtual image behind the retroreflection member 2 when viewed from the floating-in-the-air image 3 side (the corresponding user side).

[0153] FIG. 13C is a schematic diagram illustrating a configuration in which the inclination of the retroreflective module 200 relative to the liquid crystal display panel 11 and the polarization separator 101 is changed as a solution to the problem shown in FIG. 13B. In FIG. 13C, the retroreflective module 200 is rotated by a predetermined angle (θ) from the orientation shown in FIG. 13B around the optical axis 13C1 of the light emitted from the liquid crystal display panel 11, i.e., the optical axis 13C2 of the retroreflected light 13A2, which is the optical axis of the light reflected from the corresponding polarization separator 101. The angle of rotation is θ. In this orientation, the optical axis 13C3 of the ghost image 13B1 generated by the irregular image light 13A4 is tilted by an angle 2θ with respect to the optical axis 13C2 of the retroreflected light 13A2 that forms the floating-in-the-air image 3. As a result, ghost image 13B1 is out of the field of view in the direction in which the user views floating-in-the-air image 3, and the reduction in visibility of floating-in-the-air image 3 caused by ghost image 13B1 is reduced.

[0154] FIG. 13D is an explanatory diagram of the angle θ of the arrangement in FIG. 13C and the angles formed by each component. In FIG. 13D, angles A, B, and C indicate the arrangement angles of each component in the arrangement state (FIG. 13B) where ghost image 13B1 due to unnormalized image light 13A4 is strongly visible. Angle A is the angle formed between the image display device 1 including the liquid crystal display panel 11 (particularly the image light output surface) and the polarization separation member 101 (particularly the reflective surface). Angle B is the angle formed between the polarization separation member 101 (particularly the reflective surface) and the retroreflection module 200 (particularly the surface of the λ / 4 plate 21). Angle C is, for example, approximately 90 degrees, and angles A and B are each approximately 45 degrees.

[0155] In contrast, when retroreflective module 200 is rotated by angle θ (FIG. 13C), angle B changes to angle B', and angle C changes to angle C', as shown. The relationship between angle B and angle B', and the relationship between angle C and angle C', are as follows: angle B' is increased by angle θ from angle B, and angle C' is decreased by angle θ from angle C. Equation 1: B'=B+θ Equation 2: C'=C-θ

[0156] <Ghost image in horizontal position> 14A is a schematic diagram illustrating the problem of ghost image 13B1 occurring due to irregular image light 13A4 as in FIG. 13A in a horizontally oriented housing such as the embodiment of FIG. 4A. In FIG. 14A, three components, namely, an image display device 1 including a liquid crystal display panel 11, a polarization separating member 101, and a retroreflective module 200, are arranged at angles A, B, and C, similar to FIG. 13D. In this configuration, angle A and angle B are approximately equal.

[0157] 14A , in the relationship between the angles (A, B, C) formed by the three components of the retroreflective module 200, including the liquid crystal display panel 11, the polarization separating member 101, and the λ / 4 plate 21, when angle A and angle B are approximately equal, the irregular image light 13A4 due to the specular reflection of the λ / 4 plate 21 overlaps with the regular image light 13A2 that forms the floating-in-the-air image 3. As a result, as shown in FIG. 13B , a ghost image 13B1 due to the irregular image light 13A4 appears on the opposite side of the floating-in-the-air image 3, behind the retroreflective module 200, in the direction in which the floating-in-the-air image 3 is viewed from the viewpoint of the user 230. The overlap of this ghost image 13B1 with the floating-in-the-air image 3 reduces the visibility of the floating-in-the-air image 3 as seen by the user 230.

[0158] <Ghost image in vertical placement> Similarly, FIG. 14B is a schematic explanatory diagram illustrating the problem of ghost image 13B1 caused by irregular image light 13A4, as in FIG. 13A, in a vertically oriented housing such as the embodiment of FIG. 4B. In FIG. 14B, the three components are arranged at angles A, B, and C, similar to FIG. 13D. In this configuration, angles A and B are approximately equal. Even in this configuration, irregular image light 13A4, which is specularly reflected by the λ / 4 plate 21, overlaps with regular image light 13A2 forming the floating-in-the-air image 3. As a result, as shown in FIG. 13B, a ghost image 13B1 caused by irregular image light 13A4 appears on the opposite side of the floating-in-the-air image 3, behind the retroreflective module 200, in the direction in which the floating-in-the-air image 3 is viewed from the user's viewpoint. The overlap of this ghost image 13B1 with the floating-in-the-air image 3 reduces the visibility of the floating-in-the-air image 3 from the user's perspective.

[0159] <Example 1A for reducing ghost images in a horizontally placed housing> 15A shows the configuration of a floating-in-the-air image display device according to Example 1A, which is a first example for reducing ghost images in a horizontally oriented housing. Similar to the configuration shown in FIG. 4A, Example 1A is configured such that an image display device 1 including a liquid crystal display panel 11, a polarization separator 101, and a retroreflection module 200 including a λ / 4 plate 21 are arranged in a horizontally oriented housing 1190. In this configuration, the retroreflection module 200 is tilted at an angle θ so that the angle B (B') between the retroreflection module 200 and the polarization separator 101 is larger than the angle A between the liquid crystal display panel 11 and the polarization separator 101 (B'>A). Following the change to angle A', angle C is also changed to angle C' (A+B'+C'=180 degrees).

[0160] The irregular image light 13A4 of the retroreflective module 200 passes through an optical path below (lower in the Z direction in the drawing) the regular image light 13A2 that forms the floating-in-the-air image 3. As a result, the irregular image light 13A4 is out of the field of view of the user 230, that is, out of the optical axis of the regular image light 13A2, and the ghost image 13B1 due to the irregular image light 13A4 is out of the field of view of the user 230, that is, out of the optical axis 13C3 that is tilted at an angle 2θ with respect to the optical axis 13C2 of the floating-in-the-air image 3, as shown in FIG. 13C above. Therefore, the overlap of the ghost image 13B1 with the floating-in-the-air image 3 is reduced as viewed by the user 230, and the visibility of the floating-in-the-air image 3 can be improved.

[0161] When the retroreflective module 200 rotates through an angle θ, the direction of the normal image light 13A2 retroreflected from the retroreflective module 200 remains unchanged between when it enters and when it leaves the retroreflective module 200 due to the characteristics of the retroreflective module 200. In contrast, the direction of the irregular image light 13A4 changes by an angle 2θ. Therefore, the direction of the irregular image light 13A4 can be made different from the direction of the normal image light 13A2.

[0162] The rotation axis J1 of the rotation at the angle θ is located at a position on the surface of the λ / 4 plate 21 corresponding to the optical axis of the normal image light 13A2, and extends in the X direction.

[0163] 15A, the irregular image light 13A4 from the λ / 4 plate 21 passes through the polarization separation member 101 and the transparent member 100 and is emitted to the outside of the housing 1190. As the irregular image light 13A4 (its optical axis) travels outward along the optical path, it moves away from the regular image light 13A2 (its optical axis).

[0164] According to the airborne video display device of Example 1A, as shown in the principle diagram (Fig. 13C), by the configuration in which the angle B' of the arrangement of the retroreflective module 200 is made different from the angle A, the non-normal video light 13A4 from the retroreflective module 200 travels in a shifted direction with respect to the direction of the normal video light 13A2. Therefore, when viewed from the viewpoint of the user 230, the ghost image 13B1 due to the non-normal video light 13A4 is formed at a shifted position with respect to the airborne video 3 by the normal video light 13A2, so that the visibility of the ghost image 13B1 can be reduced. In other words, when viewed from the user 230, the overlap of the ghost image 13B1 with respect to the airborne video 3 can be reduced, and the visibility of the airborne video 3 can be enhanced.

[0165] <Example 1B of reducing ghost image in horizontally placed housing> Fig. 15B shows the configuration of the airborne video display device of Example 1B as a second example of reducing the ghost image in a horizontally placed housing. The difference in the configuration of Fig. 15B compared to the configuration of Fig. 15A is that the angle B (B') made by the retroreflective module 200 with respect to the polarization beam splitter member 101 is smaller than the angle A made by the liquid crystal display panel 11 with respect to the polarization beam splitter member 101 (B' < A), and the retroreflective module 200 is arranged at an angle θ (if it is +θ in Fig. 15A, it is -θ in Fig. 15B).

[0166] In the configuration of Fig. 15B, contrary to the configuration of Fig. 15A, the non-normal reflected light 13A4 of the retroreflective module 200 passes through an optical path above (upper side in the Z direction shown in the figure) the normal video light 13A2 forming the airborne image 3. Thereby, the non-normal video light 13A4 deviates from the visual field of the user 230, that is, from the optical axis of the normal video light 13A2, and the ghost image 13B1 due to the non-normal video light 13A4 deviates onto the optical axis 13C3 inclined at an angle 2θ with respect to the optical axis 13C2 of the airborne image 3, as in the case where the direction of rotation of the angle θ in Fig. 13C described above is reversed in positive and negative. Therefore, when viewed from the user 230, the overlap of the ghost image 13B1 with respect to the airborne image 3 is reduced, so that the visibility of the airborne image 3 can be improved.

[0167] <Example 1C of reducing ghost image in vertically placed housing> Figure 15C shows the configuration of the airborne video display device of Embodiment 1C as a third embodiment for reducing ghost images in a vertically placed housing. Similar to FIG. 4B described above, in this Embodiment 1C, in the vertically placed housing 1190, a video display device 1 including a liquid crystal display panel 11, a polarization separation member 101, and a retroreflective module 200 including a λ / 4 plate 21 are arranged. In this configuration, the angle B (B’) that the retroreflective module 200 makes with respect to the polarization separation member 101 is smaller than the angle A that the liquid crystal display panel 11 makes with respect to the polarization separation member 101 (B’ < A), and the retroreflective module 200 is arranged at an angle θ.

[0168] In this configuration, the non-normal video light 13A4 of the retroreflective module 200 passes through an optical path below (lower in the Z direction shown in the figure) the normal video light 13A2 that forms the airborne image 3. As a result, the non-normal video light 13A4 deviates from the visual field of the user 230, that is, from the optical axis of the normal video light 13A2, and the ghost image 13B1 due to the non-normal video light 13A4 deviates onto the optical axis 13C3 that is inclined at an angle 2θ with respect to the optical axis 13C2 of the airborne image 3 as shown in FIG. 13C above. Therefore, as seen from the user 230, the overlap of the ghost image 13B1 with respect to the airborne image 3 is reduced, so the visibility of the airborne image 3 can be improved.

[0169] <Embodiment 1D for Reducing Ghost Images in a Vertically Placed Housing> Figure 15D shows the configuration of the airborne video display device of Embodiment 1D as a fourth embodiment for reducing ghost images in a vertically placed housing. Different from the configuration of FIG. 15C, in this Embodiment 1D, the angle B (B’) that the retroreflective module 200 makes with respect to the polarization separation member 101 is larger than the angle A that the liquid crystal display panel 11 makes with respect to the polarization separation member 101 (B’ > A), and the retroreflective module 200 is arranged at an angle θ (if it is +θ in FIG. 15C, it is -θ in FIG. 15D).

[0170] 15C, in the configuration of FIG. 15D, the irregular reflected light 13A4 of the retroreflective module 200 passes through an optical path above (above in the Z direction in the figure) the normal image light 13A2 that forms the floating-in-the-air image 3. As a result, the irregular image light 13A4 is out of the field of view of the user 230 (the optical axis of the normal image light 13A2), and the ghost image 13B1 caused by ... optical axis 13C3 that is tilted at an angle 2θ with respect to the optical axis 13C2 of the floating-in-the-air image 3, as in the case where the direction of rotation of the angle θ is reversed in FIG. 3C described above. Therefore, the overlap of the ghost image 13B1 with the floating-in-the-air image 3 is reduced as viewed by the user 230, thereby improving the visibility of the floating-in-the-air image 3.

[0171] <Example in which a light blocking portion for irregular image light is provided> Next, an embodiment will be described that is based on the above-mentioned Examples 1A to 1D and further includes a light blocking portion for the above-mentioned irregular image light 13A4 (ghost image 13B1).

[0172] <Example 2A in which a light-shielding portion is provided> FIG. 16A shows the configuration of a floating-in-the-air image display device of Example 2A as a first example in which a light-shielding portion is provided in a horizontally oriented housing. The configuration of Example 2A in FIG. 16A is based on the configuration of Example 1A in FIG. 15A and has common components. The configuration of FIG. 16A differs from the configuration of FIG. 15A in that a light-shielding portion 161A is provided in a part of the housing 1190. In the configuration of FIG. 15A, the upper surface of the housing 1190 has an area where the polarization separating member 101 and the transparent member 100 are arranged, and the normal image light 13A2 passes through this area to the outside. In addition, the non-normal image light 13A4 (its optical axis) also passes through this area to the outside. In contrast, in the configuration of FIG. 16A, the area where the polarization separating member 101 and the transparent member 100 are arranged on the upper surface of the housing 1190 is narrowed by providing the light-shielding portion 161A. The normal image light 13A2 passes through this area to the outside, but the irregular image light 13A4 (its optical axis) is blocked by the light-shielding portion 161A in this area and does not pass through to the outside. That is, the light-shielding portion 161A is provided in an area that blocks the irregular image light 13A4 that forms the ghost image, but does not block the normal image light 13A2 that forms the floating image.

[0173] In other words, in Example 2A, the area on the top surface of the housing 1190 through which the light beam of the normal image light 13A2 retroreflected from the retroreflective module 200 passes is defined by a transparent member, i.e., an opening defined by the polarization separating member 101 and the transparent member 100, and a portion of the housing 1190 is configured as a light-shielding portion 161A to block only the abnormal image light 13A4. This reduces the degree to which the light beam of the abnormal image light 13A4 enters the field of view of the user 230, so Example 2A can further reduce the reduction in visibility due to the ghost image 13B1 compared to Example 1A. In other words, the housing is provided with a transparent member corresponding to the area where the polarization separating member is arranged, and a light-shielding member is provided in an area through which the axis perpendicular to the surface of the retroreflective module passes that does not block the image light for forming the floating image. The same applies to the light-shielding portion described below.

[0174] The mid-air operation detection sensor 1351 is not blocked by the light-shielding portion 161A of the housing 1190, and senses the surface of the floating-in-the-air image 3 in the same manner as described above.

[0175] <Example 2B in which a light-shielding portion is provided> FIG. 16B shows the configuration of a floating-in-the-air image display device of Example 2B as a second example in which a light-shielding portion is provided in a horizontally oriented housing. The configuration of Example 2B in FIG. 16B is based on the configuration of Example 1B in FIG. 15B and has common components. The configuration of FIG. 16B differs from the configuration of FIG. 15B in that a light-shielding portion 161B is provided in a part of the housing 1190. In the configuration of FIG. 15B, the upper surface of the housing 1190 has an area where the polarization separating member 101 and the transparent member 100 are arranged, and the normal image light 13A2 passes through this area to the outside. The non-normal image light 13A4 (its optical axis) also passes through this area to the outside. In contrast, in the configuration of FIG. 16B, the upper surface 162 of the housing 1190 has an area where the polarization separating member 101 is arranged, and both the normal image light 13A2 and the non-normal image light 13A4 (its optical axis) pass through this area to the outside. 16B, housing 1190 has upper surface 163 as a second upper surface at a position at height H1 above upper surface 162, with space 164 therebetween. Transparent member 100 is also arranged on a slope that connects upper surface 162 and upper surface 163.

[0176] In this configuration, if a light shielding portion for shielding the irregular image light 13A4 is provided in the region of the upper surface 162 where the polarization separating member 101 is disposed, the light beam of the regular image light 13A2 would also be shielded. Therefore, a light shielding portion 161B is provided as part of the housing 1190 on the upper surface 163, which is located at a higher position. As shown in the figure, this light shielding portion 161B shields the irregular image light 13A4 (its optical axis) without shielding the light beam of the regular image light 13A2. The light beam of the regular image light 13A2 passes through the polarization separating member 101 and the transparent member 100 and exits to the outside. The irregular image light 13A4 passes through the polarization separating member 101 and is shielded by the light shielding portion 161B. This reduces the degree to which the light beam of the irregular image light 13A4 enters the field of view of the user 230. Therefore, in this Example 2B, the degradation of visibility due to the ghost image 13B1 can be further reduced compared to Example 1B. That is, the housing has a transparent member on a first housing surface, that is, top surface 162, and a light-shielding portion on a second housing surface, that is, top surface 163, which is a predetermined distance outward from the first housing surface.

[0177] Note that the space 164 provided between the upper surface 162 and the upper surface 163 can be used for any purpose, such as arranging other members. For example, a mid-air operation detection sensor 1351 may be arranged in this space 164.

[0178] <Example 2C in which a light-shielding portion is provided> 16C shows the configuration of Example 2C as a third example in which a light-shielding portion is provided in a vertically-mounted housing. FIG. 16C differs from the configuration of FIG. 15D in that a light-shielding portion 161C is provided on a part of the front surface of the housing 1190. This light-shielding portion 161C is provided at a position where the irregular image light 13A4 (its optical axis) passes through, and blocks the irregular image light 13A4 (its optical axis) without blocking the light beam of the regular image light 13A2. This reduces the degree to which the light beam of the irregular image light 13A4 enters the field of view of the user 230, so Example 2C can further reduce the degradation of visibility due to the ghost image 13B1 compared to Example 1D.

[0179] <Example 2D in which a light-shielding portion is provided> FIG. 16D shows the configuration of Example 2D as a fourth example in which a light-shielding unit is provided in a vertically oriented housing. Example 2D is an example in which a light-shielding unit similar to Example 2B is applied to a vertically oriented housing. FIG. 16D differs from the configuration of FIG. 15C in that a region in the front surface 166 of the housing 1190 where the polarization separating member 101 is disposed is provided. In this region, both the normal image light 13A2 and the non-normal image light 13A4 (their optical axes) pass through. In the configuration of FIG. 16D, the housing 1190 is provided with a front surface 167 as a second front surface at a distance D1 further forward than the front surface 166, with a space 168 therebetween. A transparent member 100 is also provided on the slope to connect the front surfaces 166 and 167.

[0180] In this configuration, if a light shielding portion for shielding the irregular image light 13A4 is provided in the region of the front surface 166 where the polarization separating member 101 is disposed, the light beam of the regular image light 13A2 would also be shielded. Therefore, a light shielding portion 161D is provided as part of the housing 1190 on the front surface 167, which is located further forward. As shown in the figure, this light shielding portion 161D shields the irregular image light 13A4 (its optical axis) without shielding the light beam of the regular image light 13A2. The light beam of the regular image light 13A2 passes through the polarization separating member 101 and the transparent member 100 and exits to the outside. The irregular image light 13A4 passes through the polarization separating member 101 and is shielded by the light shielding portion 161D. This reduces the degree to which the light beam of the irregular image light 13A4 enters the field of view of the user 230. Therefore, in this Example 2D, the degradation of visibility due to the ghost image 13B1 can be further reduced compared to Example 1C.

[0181] Note that a space 168 provided between the front surfaces 166 and 167 can be used for any purpose, such as arranging other members. For example, a mid-air operation detection sensor 1351 may be arranged in this space 168.

[0182] <Example in which a holding unit is provided> Next, an embodiment will be described in which a holding unit for mounting and holding the image display device 1, the polarization separating member 101, and the retroreflection module 200 on the housing 1190 of the floating image display device of the above embodiment is provided.

[0183] <Example 3A in which a holding unit is provided> 17A shows the configuration of a floating-in-the-air image display device according to Example 3A, which is an example in which a predetermined holding unit 2000 is provided in the case of, for example, a horizontally placed housing 1190 (such as Example 1A in FIG. 15A). In Example 3A, the components of the retroreflection module 200, including the image display device 1, the polarization separating member 101, and the λ / 4 plate 21, are held in a predetermined positional relationship by the holding unit 2000. The holding unit 2000 is attached so as to be held by the housing 1190. The predetermined positional relationship includes the angular relationship described above.

[0184] In FIG. 17A, the outline of the shape of the holding unit 2000 is shown by a dashed line, and details will be described later. In the illustrated yz plane, the image display device 1 is held by a first surface of the holding unit 2000, the polarization separation member 101 is held by a second surface of the holding unit 2000, and the retroreflection module 200 is held by a third surface of the holding unit 2000. The second surface of the holding unit 2000 is disposed parallel to the surface of the transparent member 100 on the upper surface of the housing 1190. As described above (e.g., Example 1A in FIG. 15A), the surface of the liquid crystal display panel 11 is held so that it forms an angle A with respect to the surface of the polarization separation member 101, and the surface of the λ / 4 plate 21 of the retroreflection module 200 is held so that it forms an angle B' (e.g., B' > A) with respect to the surface of the polarization separation member 101. This holding unit 2000 can stably hold the three components while maintaining a predetermined angular relationship.

[0185] <Example 3B in which a holding unit is provided> FIG. 17B shows the configuration of the airborne floating video display device of Example 3B as an example in which a predetermined holding unit 2000 is provided in the case of the housing 1190 which is, for example, a vertically placed housing (Example 1C in FIG. 15C, etc.). In this Example 3B, as in Example 3A, the above-described three components are held in a predetermined positional relationship by the holding unit 2000. The holding unit 2000 is attached so as to be held by the housing 1190. In the illustrated y-z plane, the video display device 1 is held with respect to the first surface of the holding unit 2000, the polarization separation member 101 is held with respect to the second surface of the holding unit 2000, and the retroreflective module 200 is held with respect to the third surface of the holding unit 2000. The second surface of the holding unit 2000 is arranged parallel to the surface of the transparent member 100 on the front surface of the housing 1190. Similar to the above (for example, Example 1C in FIG. 15C), the surface of the liquid crystal display panel 11 makes an angle A with respect to the surface of the polarization separation member 101, and the surface of the λ / 4 plate 21 of the retroreflective module 200 makes an angle B' (for example, B' < A) with respect to the surface of the polarization separation member 101. With such a holding unit 2000, the three components can be stably held while maintaining a predetermined angular relationship.

[0186] <Structural Example of Holding Unit: Example 4A> FIG. 18A is a perspective view showing a detailed example of the structure of the holding unit 2000 shown in FIGS. 17A and 17B as Example 4A. FIG. 18A shows a state in which only the image display device 1 is attached to the holding unit 2000. The holding unit 2000 has first, second, and third surfaces for holding the three components described above, namely, the image display device 1, the polarization separating member 101, and the retroreflective module 200. The holding unit 2000 also has a side surface 2001, or in other words, a side cover, disposed on the yz plane of the housing 1190 shown in FIG. 17A as a side surface. Three sides of the roughly triangular surface of the side surface 2001 are adjacent to the corresponding sides of the first, second, and third surfaces. The image display device 1 is fixed to the first surface of the holding unit 2000. The polarization separating member 101 described above is fixed to the second surface of the holding unit 2000. The retroreflective module 200 is fixed to the third surface of the holding unit 2000 using a holding member 2002. The holding unit has side portions that hold the first, second, and third surfaces, and the side portions have holding members for attaching the retroreflective module at a second angle, i.e., the angle that the retroreflective module makes with respect to the polarization separating member.

[0187] The holding unit 2000 has holding members 2002 fixed to each of side surfaces 2001 arranged at front and rear positions in the x direction. The holding members 2002 are members for attaching and holding the retroreflective modules 200. Two holding members 2002 are fixed to each of the side surfaces 2001. For example, one of the side surfaces 2001 (left side in FIG. 18A ) has a first holding member 2002A1 and a second holding member 2002B1 on the inside, and the other side surface 2001 (right side in FIG. 18A ) has a first holding member 2002A2 and a second holding member 2002B2 on the inside. In other words, the side surface includes a first holding member for mounting the retroreflective module at a first angle, i.e., a second angle greater than the angle of the image display device relative to the polarization separating member (i.e., the angle of the retroreflective module relative to the polarization separating member), and a second holding member for mounting the retroreflective module at a second angle smaller than the first angle, i.e., the angle of the image display device relative to the polarization separating member (i.e., the angle of the retroreflective module relative to the polarization separating member). The first holding member and the second holding member are components having the same shape and structure.

[0188] Each holding member 2002 is fixed to the side surface portion 2001 (its screw holes, etc.) by, for example, screwing. Each side surface portion 2001 also has an attachment portion 2003 for attaching the holding unit 2000 to the housing 1190. The side surface may have a holding member for attaching the retroreflective module at a first angle, i.e., a second angle that is larger than the angle that the image display device makes with respect to the polarization separation member, i.e., the angle that the retroreflective module makes with respect to the polarization separation member, or may have a holding member for attaching the retroreflective module at a second angle that is smaller than the first angle, i.e., the angle that the image display device makes with respect to the polarization separation member, i.e., the angle that the retroreflective module makes with respect to the polarization separation member.

[0189] In this Example 4A, the holding unit 2000 is provided with multiple holding members 2002 so that the retroreflective module 200 can be positioned at a selected angle from two angles (the aforementioned angle B'). For example, when the retroreflective module 200 is positioned at a first angle (e.g., angle B' in Example 1A of FIG. 15A), holding members 2002A1 and 2002A2 are selected, and when the retroreflective module 200 is positioned at a second angle (e.g., Example 1B of FIG. 15B), holding members 2002B1 and 2002B2 are selected. As described above, angle C' is also determined according to angle B'.

[0190] FIG. 18B is a schematic diagram showing the outline of the structure of one holding member 2002 (for example, holding member 2002A1). Each holding member 2002 consists of a pair of structures. For example, holding member 2002A1 consists of holding structure 2004a and holding structure 2004b. The upper holding structure 2004a and the lower holding structure 2004b are each roughly plate-shaped structures, and are fixed to the side portion 2001 by screws. The lower holding structure 2004b has a stopper on the back side (the side closer to the first surface). A space or groove is provided at a predetermined distance between the upper holding structure 2004a and the lower holding structure 2004b.

[0191] When the retroreflective module 200 is attached to the holding member 2002, an end of the retroreflective module 200 is inserted in the direction of the arrow shown in the figure into a groove formed by the holding structures 2004a and 2004b of the holding member 2002. Upon insertion, the end of the retroreflective module 200 abuts against a stopper portion of the holding structure 2004b at the back of the holding member 2002. The portion of the retroreflective module 200 inserted between the upper holding structure 2004a and the lower holding structure 2004b is sandwiched from above and below and pressed by the leaf springs of the two structures, thereby being held in place.

[0192] After one portion of retroreflective module 200 is inserted into holding member 2002 in the same manner at each side surface 2001, the other portion of retroreflective module 200 (the side closer to the second surface) is fixed with, for example, a cushioning material and a lid to prevent the module from moving in the direction of the main surface. This fixes retroreflective module 200 at the selected angle to holding member 2002 closer to the third surface.

[0193] The four holding members 2002 (for example, holding members 2002A1, 2002B1, 2002A2, and 2002B2) are configured as the same parts having the same shape, etc., and the same parts can be applied regardless of the position at which they are attached.

[0194] Fig. 18C shows two types of angles in a cross-sectional view (yz plane) of the holding unit 2000. Note that Fig. 18C shows holding members 2002A1 and 2002B1 of one of the holding members 2002 of the two side surface portions 2001 in Fig. 18A, but holding members 2002A2 and 2002B2 of the other side surface portion 2001 are also arranged in the same corresponding positions. Figure 18C shows the angle A made by the first surface SF1 of the image display device 1 relative to the second surface SF2 to which the polarization separation member 101 in the holding unit 2000 is fixed, the angle BA made by the holding member 2002A1 (particularly surface SF3A) relative to the second surface SF2 of the polarization separation member 101, the angle CA made by the first surface SF1 of the image display device 1 and the holding member 2002A1 (surface SF3A), the angle BB made by the holding member 2002B1 (particularly surface SF3B) relative to the second surface SF2 of the polarization separation member 101, and the angle CB made by the first surface SF1 of the image display device 1 and the holding member 2002B1 (surface SF3A).

[0195] The angle A formed by the image display device 1, the angle BA formed by the holding member 2002A1, and the angle BB formed by the holding member 2002B1 with respect to the second surface SF2 of the polarization separation member 101 are all different (A≠BA≠BB), and the angle BA is larger than the angle A (BA>A), and the angle BB is smaller than the angle A (BB <A)。

[0196] As for the arrangement of the retroreflective module 200 with respect to the two types of holding members 2002, when selecting the holding member 2002A1 that forms the angles BA and CA, it corresponds to the arrangement (angle B'>A) such as in Example 1A of FIG. 15A described above. When selecting the holding member 2002B1 that forms the angles BB and CB, it corresponds to the arrangement (angle B'<A) such as in Example 1B of FIG. 15B described above.

[0197] FIG. 18D shows a state where the retroreflective module 200 is inserted and attached to the holding members 2002A1 and 2002A2 corresponding to the angle BA among the two types of holding members 2002 in the holding unit 2000 of FIG. 18C. The λ / 4 plate 21 of the retroreflective module 200 is arranged along the surface SF3A corresponding to the holding member 2002A1. The retroreflective module 200 is arranged at the angle BA, and the non-normal video light 13A4 is emitted from the optical path on the lower side with respect to the normal video light 13A2 at the aforementioned angle 2θ.

[0198] FIG. 18E shows a state where the retroreflective module 200 is inserted and attached to the holding members 2002B1 and 2002B2 corresponding to the angle BB among the two types of holding members 2002 in the holding unit 2000 of FIG. 18C. The λ / 4 plate 21 of the retroreflective module 200 is arranged along the surface SF3B corresponding to the holding member 2002B1. The retroreflective module 200 is arranged at the angle BB, and the non-normal video light 13A4 is emitted from the optical path on the upper side with respect to the normal video light 13A2 at the aforementioned angle 2θ.

[0199] As described above, in Example 4A, according to the mounting form of the airborne floating video display device, it is possible to select the desired angle from the two types of angles from the two types of holding members 2002 of the holding unit 2000 and attach the retroreflective module 200. In Example 4A, the same one holding unit 2000 can correspond to the mounting forms of two types of angles.

[0200] 18F is an explanatory diagram of mounting holes (screw holes) 2005 provided in side surface portion 2001 of holding unit 2000. Each side surface portion 2001 is provided with mounting holes 2005a, 2005b, 2005c, and 2005d at predetermined positions as mounting holes (e.g., screw-enabled screw holes) 2005 for attaching the two types of holding members 2002. Using these mounting holes 2005, holding unit 2000 may be a unit to which the two types of holding members 2002 are fixed, or a unit to which only one type of holding member 2002 is fixed, and is adaptable to both cases. Holding members 2002 at two different angles relative to mounting holes 2005 can be made to have the same shape and structure, so multiple holding components 2002 can be manufactured and managed as a single type of component.

[0201] As another embodiment, a configuration in which only holding members 2002 of one type of angle are attached to the holding unit 2000 is also possible.

[0202] <Structural example of holding unit: Example 4B> FIG. 19A shows the configuration of a holding unit 2000 as Example 4B. The holding unit 2000 in Example 4B has a structure including a rotation mechanism for positioning the retroreflective module 200 at a predetermined angle, which differs from the structure of the holding unit 2000 in Example 4A. In FIG. 19A, the holding unit 2000 has a rotation mechanism 190 provided between the side surface portions 2001 and near the third surface SF3 on which the retroreflective module 200 is disposed. The rotation mechanism 190 is a mechanism that can rotate the held retroreflective module 200 around a rotation axis 190J. The rotation axis 190J is an axis extending in the x-direction. The rotation axis 190J of the rotation mechanism 190 is located at a position that substantially coincides with the position of the optical axis AX2 of the floating-in-the-air image 3 (corresponding normal image light 13A2). The optical axis AX2 corresponds to the optical axis of the reflected light by the polarization separation member 101, relative to the optical axis AX1 of the image light from the liquid crystal display panel 11. The holding unit has a side surface that holds the first, second, and third surfaces, and a rotation mechanism that mounts the retroreflective module on the side surface at the second angle, i.e., the angle that the retroreflective module makes with respect to the polarization separating member. The rotation mechanism has a rotation axis at a position corresponding to the position of the optical axis of the reflected image light from the polarization separating member.

[0203] Retroreflective module 200 fixed to rotation mechanism 190 can be rotated around rotation axis 190J to be positioned at an angle selected from at least the two angles (BA, BB) mentioned above, as indicated by the dashed line. Rotation mechanism 190 is not limited to the two angles (BA, BB), and may be a mechanism that can be positioned at an angle set within the range of these angles.

[0204] 19B shows a modification of Example 4B. The rotation mechanism 190 is not limited to a configuration in which the rotation axis 190J is provided at a position corresponding to the optical axis AX2, which is a position near the center of the retroreflection module 200, but may also be configured to provide the rotation axis 190J at another position. In the configuration example of FIG. 19B, the rotation axis 190J is provided near the end of the third surface SF3 closer to the polarization separation member 101, which is one end of the retroreflection module 200. In this modification, the angle at which the retroreflection module 200 is disposed can also be set to the two angles mentioned above.

[0205] When the rotation mechanism 190 is configured to have a rotation axis 190J at a position corresponding to the optical axis AX2 as in Example 4B, and the retroreflection module 200 is rotated by an angle ±θ from the standard state of the retroreflection module 200, the distance on the optical axis at which the reflected image light from the polarization separation member 101 is incident is kept constant between the polarization separation member 101 and the retroreflection module 200. Therefore, Example 4B has the advantage of making it easier to manage optical performance in terms of design than the modified example.

[0206] As explained above, according to the space floating image display device of each embodiment, the user 230 can visually recognize the space floating image 3 more favorably.

[0207] <Regarding the angle of retroreflective module placement> A supplementary explanation will be given regarding the angle B' of the arrangement of the retroreflective module 200 in Example 1A and the like. As described above, a basic feature of Example 1A and the like is that, unlike the conventional arrangement where angle B = angle A, angle B' is different from angle A. Regarding the arrangement angle of the retroreflective module 200, the configuration where angle B = angle A is taken as the standard state, as shown in FIG. 14A and the like. In this standard state, the surface of the λ / 4 plate 21, which is the main surface of the retroreflective module 200, is perpendicular to the optical axis of the reflected image light from the polarization separator 101. In contrast, in Example 1A and the like, the retroreflective module 200 is tilted forward and backward by angle θ, as described above, so that angle B' is different from angle A. In other words, the relationship between angles A, B', and C' is as shown in FIG. 13D and Equation 1, Equation 2, and the like.

[0208] The value of angle B' can be implemented as follows, for example. In the standard state, angle A=B is, for example, 45 degrees. Of course, this angle A=B is not limited to 45 degrees. In Example 1A and the like, angle B' is an angle that differs by ±X degrees from angle A=45 degrees. In one example, if X=11 degrees, angle B'=45 degrees+11 degrees=56 degrees. Of course, angle X is not limited to this and can be any angle within a predetermined range (Xmin≦X≦Xmax).

[0209] The technology according to this embodiment displays high-resolution, high-brightness images in a floating state, allowing users to operate the device without worrying about contact infection. Applying the technology according to this embodiment to a system used by an unspecified number of users reduces the risk of contact infection and provides a contactless user interface that can be used without anxiety. This contributes to the "Good Health and Well-Being" goal of the United Nations' Sustainable Development Goals (SDGs).

[0210] Furthermore, the technology of this embodiment reduces the divergence angle of the emitted image light and aligns it with a specific polarization, thereby efficiently reflecting only the normal reflected light from the retroreflector, thereby enabling high light utilization efficiency and producing bright and clear floating images in space.The technology of this embodiment can provide a highly usable non-contact user interface that can significantly reduce power consumption.This contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote technological innovation and infrastructure" and "Make cities and human settlements sustainable."

[0211] Various embodiments have been described above in detail. However, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system to clearly explain the present invention, and the present invention is not necessarily limited to a system including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0212] 1...display device (image display device), 2...retroreflector (retroreflector, retroreflective member), 3...spatial image (space-floating image), 100...transparent member, 101...polarized light separation member, 11...liquid crystal display panel, 12...absorptive polarizer, 13...light source device, 21...λ / 4 plate, 200...retroreflective module, 230...user, 1190...housing, 1351...air operation detection sensor, 13A2...regular image light, 13A4...irregular image light.

Claims

1. A floating-in-the-air image display device that displays floating-in-the-air images, A video display device; a polarization separation member that reflects image light of a specific polarization from the image display device and transmits image light of the other polarization; a retroreflection module having a λ / 4 plate and a retroreflection member that retroreflects reflected image light of a specific polarized wave from the polarization separation member and converts it into image light of the other polarized wave; a housing that holds the image display device, the polarization separating member, and the retroreflective module, The image light of the other polarized wave from the retroreflection module is transmitted through the polarization separation member to form the floating image, which is a real image, at a predetermined position outside the housing; a first angle formed by the image display device with respect to the polarization separating member and a second angle formed by the retroreflective module with respect to the polarization separating member, the second angle being different from the first angle; a holding unit that holds the image display device, the polarization separating member, and the retroreflective module so as to satisfy the relationship and is fixed to the housing; A floating video display device.

2. 2. The airborne image display device according to claim 1, The second angle is greater than the first angle. A floating video display device.

3. 2. The airborne image display device according to claim 1, the second angle is smaller than the first angle; A floating video display device.

4. 2. The airborne image display device according to claim 1, The housing is provided with a transparent member corresponding to the area where the polarization separation member is arranged, and a light-shielding portion is provided in an area where the axis perpendicular to the surface of the retroreflective module passes and does not block the image light for forming the floating image. A floating video display device.

5. 5. The airborne image display device according to claim 4, The housing has the polarization separating member provided on a first housing surface, and the light blocking portion provided on a second housing surface that is a predetermined distance outward from the first housing surface. A floating video display device.

6. 2. The airborne image display device according to claim 1, the holding unit has a first surface to which the image display device is attached, a second surface to which the polarization separating member is attached, and a third surface to which the retroreflection module is attached; A floating video display device.

7. 7. The airborne image display device according to claim 6, the holding unit has a side surface portion that holds the first surface, the second surface, and the third surface; a holding member for attaching the retroreflective module to the side surface at the second angle; A floating video display device.

8. 8. The airborne image display device according to claim 7, The side surface portion has a holding member for mounting the retroreflective module at the second angle, the second angle being larger than the first angle. A floating video display device.

9. 8. The airborne image display device according to claim 7, The side surface portion has a holding member for mounting the retroreflective module at the second angle which is smaller than the first angle. A floating video display device.

10. 8. The airborne image display device according to claim 7, The side surface portion has, as the holding members, a first holding member for attaching the retroreflective module so that the second angle is larger than the first angle, and a second holding member for attaching the retroreflective module so that the second angle is smaller than the first angle. A floating video display device.

11. 11. The airborne image display device according to claim 10, The first holding member and the second holding member are parts having the same shape and structure. A floating video display device.

12. 7. The airborne image display device according to claim 6, the holding unit has a side surface portion that holds the first surface, the second surface, and the third surface; a rotation mechanism for mounting the retroreflective module on the side surface at the second angle; A floating video display device.

13. 13. The airborne image display device according to claim 12, the rotation mechanism has a rotation axis at a position corresponding to the position of the optical axis of the reflected image light from the polarization separation member. A floating video display device.

Images