Aerial floating image display device

Abstract

The present invention provides a more suitable aerial floating image display device. The present invention contributes to the Sustainable Development Goals "3. Good health and well-being", "9. Industry, innovation and infrastructure", and "11. Sustainable cities and communities". This aerial floating image display device comprises: an image source; and an optical system that generates aerial floating image generation light for forming an aerial floating image on the basis of image light generated by the image source. The optical system has a transparent member on which a decorative printing layer is laminated. The aerial floating image is generated by light that has passed through the transparent member on which the decorative printing layer is laminated.

Description

Floating image display device

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

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

[0003] Japanese Patent Application Laid-Open No. 2019-128722

[0004] However, the disclosure of Patent Document 1 does not sufficiently consider configurations for obtaining practical brightness and quality for the floating image, or configurations for allowing users 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.

[0006] In order 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, and an example thereof is as follows: A floating-in-the-air image display device includes an image source and an optical system that generates floating-in-the-air image generating light for forming a floating-in-the-air image based on the image light generated by the image source, the optical system having a transparent member on which a decorative print layer is laminated, and the floating-in-the-air image is generated by light that has passed through the transparent member on which the decorative print layer is laminated.

[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.

[0008] 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. FIG. 2 is a diagram showing an example of a configuration of a main part and a retroreflector of a space-floating image display device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of a configuration of a main part and a retroreflector of a space-floating image display device according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a configuration of a main part and a retroreflector of a space-floating image display device according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of a configuration of a main part and a retroreflector of a space-floating image display device according to an embodiment of the present invention. FIG. 6 is a projection diagram of a retroreflector constituting a space-floating image display device according to an embodiment of the present invention. FIG. 7 is a top view of a retroreflector constituting a space-floating image display device according to an embodiment of the present invention. FIG. 8 is a perspective view of a corner reflector constituting a retroreflector constituting a space-floating image display device according to an embodiment of the present invention. FIG. 9 is a top view of a corner reflector constituting a retroreflector constituting a space-floating image display device according to an embodiment of the present invention. FIG. 10 is a side view of a corner reflector constituting a retroreflector constituting a space-floating image display device according to an embodiment of the present invention. FIG. 11 is a diagram showing an example of a configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 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. FIG. 2 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 7 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 8 is a diagram showing an example of the configuration of a space-floating image display device according to an embodiment of the present invention.FIG. 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. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. FIG. 3 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. FIG. 4 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. FIG. 5 is a layout diagram showing a main part of a space-floating image display device according to an embodiment of the present invention. FIG. 6 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. FIG. 7 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. FIG. 8 is an explanatory diagram for explaining light source diffusion characteristics of an image display device according to an embodiment of the present invention. FIG. 9 is an explanatory diagram for explaining diffusion characteristics of an image display device according to an embodiment of the present invention. FIG. 10 is an explanatory diagram for explaining an example of a problem solved by image processing according to an embodiment of the present invention. FIG. 11 is an explanatory diagram for explaining an example of image processing according to an embodiment of the present invention. FIG. 12 is an explanatory diagram for explaining an example of image display processing according to an embodiment of the present invention. FIG. 13 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. FIG. 14 is a diagram showing another example of the main part configuration of a space-floating image display device according to an embodiment of the present invention. FIG. 15 is a diagram showing an example of a decorative printed sheet used in a space-floating image display device according to an embodiment of the present invention. FIG. 1 is a diagram showing an example of a decorative printed sheet used in a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a decorative printed sheet used in a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of a decorative printed sheet used in a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a display device used in a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of an image light control sheet used in a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 6 is a diagram showing another embodiment of the main components of a floating-in-the-air image display device according to an embodiment of the present invention. FIG. 7 is a diagram showing an example of the shape of a decorative printed sheet used in a floating-in-the-air image display device according to an embodiment of the present 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, a suitable image display device can be realized for, for example, bank ATMs, train station ticket machines, digital signage, and the like. For example, currently, bank ATMs, train station ticket machines, and the like typically use touch panels, but 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, resulting in high light utilization efficiency and suppressing 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, a device including the light source of this embodiment can provide a novel, highly usable floating image display device (floating image display system) 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 Usage of the Space-Floating Image Display Device> Figure 1 is a diagram showing an example of usage 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 Figure 2 and other figures. Light with a narrow-angle directional characteristic and specific polarization is emitted from the image display device 1 as an image light beam, reflected by the optical system within the space-floating image display device, and then incident on the retroreflector 2, retroreflected and transmitted through a transparent member 100 (glass, etc.), forming a real aerial image (space-floating image 3) on the outside of the glass surface. In the following examples, the retroreflector 2 (retroreflector) will be used as an example of the retroreflector. However, the retroreflector 2 of the present invention is not limited to a planar plate, and 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. Furthermore, since the light rays reflected by the retroreflector 2 have the optical property of forming an image, the retroreflector 2 may also be expressed as an imaging optical member or an imaging optical plate.

[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 transparent 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 in the window glass 105, it is possible to form an aerial image at a desired position inside the store by reflecting the specific polarized waves.

[0015] <Configuration Example of Optical System of Space-Floating Image Display Device> Figure 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 Figure 2A. As shown in Figure 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 separation member 101 (in the figure, the polarization separation member 101 is formed in a sheet shape and adhered to the transparent member 100) provided on a transparent member 100 and has a film that selectively reflects image light of a specific polarization, 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 is polarized and converted from the specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, once when entering the retroreflector 2 and once when exiting. Here, the polarization separation member 101, which 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 separation member 101. The image light that has passed through the polarization separation member 101 forms a spatially floating image 3, which is a real image, outside the transparent member 100. 2A shows an example in which the chief ray of the image light incident on the retroreflector 2 is incident at an angle of 90° to the retroreflector 2. However, the incident angle of the chief ray of the image light on the retroreflector 2 is not limited to 90°, and an angle of, for example, 90°±15° can also be used.

[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 the display device 1 to the polarization separation member 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 the polarization separation member 101 from the display device 1 is reflected by the polarization separation member 101 and travels toward the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes twice through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2, thereby converting the S-polarized light to P-polarized light. The P-polarized image light then travels back toward the polarization separation member 101. Here, the polarization separation member 101 has the property of reflecting S-polarized light and transmitting P-polarized light, so the P-polarized image light passes through the polarization separation member 101 and then through the transparent member 100. The image light transmitted through the transparent member 100 is 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 the display device 1 to the polarization separation member 101, and the polarization separation member 101 has the property of reflecting P-polarized light and transmitting S-polarized light. In this case, the P-polarized image light that reaches the polarization separation member 101 from the display device 1 is reflected by the polarization separation member 101 and proceeds toward the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes twice through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2, thereby converting the image light from P-polarized light to S-polarized light. The image light converted to S-polarized light proceeds again toward the polarization separation member 101. Here, the polarization separation member 101 has the property of reflecting P-polarized light and transmitting S-polarized light, so the S-polarized image light passes through the polarization separation member 101 and then through the transparent member 100. The image light transmitted through the transparent member 100 is 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 forming the space-floating image 3 is a collection of light rays that converge from the retroreflector 2 to the optical image of the space-floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the space-floating image 3. Therefore, the space-floating image 3 is an image with high directionality, unlike the diffuse image light formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2A, when a user views the 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 seen as an image at all. This characteristic is very suitable for use in systems that display 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 the polarization separation member. Such light with an unintended polarization state and propagation angle may be reflected by components within the space-floating image display device and then re-enter the image display surface of the liquid crystal display panel 11. 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 absorbing polarizer 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorbing 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 absorbing 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 absorbing 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] 2A(2) shows an example of the surface shape of a typical retroreflector 2. Light rays incident on the interior of 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 on the display device 1 based on the image displayed.

[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, in order 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. Furthermore, it is advisable to arrange the shape so that none of the sides of the retroreflective portion overlaps 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 thereof 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. These may also be referred to as corner reflector arrays or polyhedral reflector arrays. 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 configuration example of the optical system of the space-floating image display device will be described 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 such components, repeated explanations will be omitted to simplify the explanation.

[0027] In the optical system of FIG. 2B , similar to 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 separation member 101B. The polarization separation member 101B is a member that selectively transmits image light of a specific polarization. Unlike the polarization separation member 101 of FIG. 2A , the polarization separation member 101B is not integrated with the transparent member 100 but has an independent plate-like shape. Therefore, the polarization separation member 101B may also be referred to as a polarization separation plate. The polarization separation member 101B may be configured as a reflective polarizing plate configured by attaching a polarization separation sheet to a transparent member. 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 separation member 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 the display device 1 to the polarization separation member 101B, and the polarization separation member 101B has the property of reflecting S-polarized light and transmitting P-polarized light. In this case, the P-polarized image light that reaches the polarization separation member 101B from the display device 1 passes through the polarization separation member 101B and proceeds to the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes twice through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2, and the image light is converted from P-polarized light to S-polarized light. The image light converted to S-polarized light proceeds again to the polarization separation member 101B. Here, the polarization separation member 101B has the property of reflecting S-polarized light and transmitting P-polarized light, so the S-polarized image light is reflected by the polarization separation member 101 and passes through the transparent member 100. The image light transmitted through the transparent member 100 is 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 101B. This polarization design allows the 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 the display device 1 to the 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 the polarization separator 101B from the display device 1 passes through the polarization separator 101B and proceeds to the retroreflector 2. When the image light is reflected by the retroreflector 2, it passes twice through the λ / 4 plate 21 provided on the incident surface of the retroreflector 2, thereby converting the S-polarized image light to P-polarized light. The P-polarized image light then proceeds again to the polarization separator 101B. Here, the 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 the polarization separator 101 and passes through the 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 101B. This polarization design allows the 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 separation member 101B is arranged at an angle α (e.g., 30°) with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. Then, upon reflection by the polarization separation member 101B, the direction of travel of the image light reflected by the polarization separation member 101B (the direction of the chief ray of the image light) differs by an angle β (e.g., 60°) from the direction of travel of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light). With this configuration, in the optical system of FIG. 2B , the image light is output at a predetermined angle shown toward the outside of the transparent member 100, forming a real image, the floating-in-space image 3. In the configuration of FIG. 2B , when viewed by a user from the direction of arrow A, the floating-in-space image 3 is perceived as a bright image. However, when viewed by another person from the direction of arrow B, the floating-in-space 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 light of the image light from the polarization separation member 101B and absorb the polarized light that is 90° out of phase with the polarized light 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 configuration example of the optical system of the space-floating image display device will be described using Fig. 2C. Note that 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 of Fig. 2B and the optical system of Fig. 2C is the arrangement angle of the polarization separation member 101B with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. All other configurations are the same as those of the optical system of Fig. 2B, so repeated explanations will be omitted. The polarization design of the optical system of Fig. 2C is also the same as that of the optical system of Fig. 2B, so repeated explanations will be omitted.

[0036] In the optical system of FIG. 2C , the polarization separation member 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 separation member 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 separation member 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 separation member 101B, thereby simplifying the angular relationship between the surfaces that make up the optical system. If the surface of the transparent member 100 is positioned perpendicular to the direction of propagation of the image light reflected by the polarization separation member 101B, the angular relationship between 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 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 light of the image light from the polarization separation member 101B and absorb the polarized light that is 90° out of phase with the polarized light 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. 2C due to the external light incident on the space-floating image 3 side of the transparent member 100.

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

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

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

[0042] The retroreflector 5 is an optical element having the optical property of retroreflecting light rays in at least some directions. Furthermore, since the reflected light rays have the optical property of forming an image, the retroreflector 5 may also be referred to as an imaging optical element or an imaging optical plate.

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

[0044] The light beam forming the space-floating image 3 is a collection of light rays that converge from the retroreflector 5 to the optical image of the space-floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the space-floating image 3. Therefore, the space-floating image 3 is an image with high directionality, unlike a diffuse image formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2, when a user views the 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 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.

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

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

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

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

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

[0050] As described above, the light rays incident on the corner reflector 9040 undergo retroreflection, which results in an inverted optical path in the x and y directions, and specular reflection due to total reflection in the z direction. Considering the retroreflector 5, similar reflection occurs in each optical path, so that an image is formed at a point symmetrical with respect to the z axis direction by an inverted optical path that is convergent in the x and y directions.

[0051] 2A to 2C, the retroreflector 2 has retroreflection properties in three axes. As a result, when a diffusive incident light beam is incident on the retroreflector 2, a convergent reflected light beam travels toward the side of the retroreflector 2 where the light source of the incident light is located. The convergent reflected light beam forms an image in the air, forming a floating image 3. The traveling direction of the chief ray of the convergent reflected light beam reflected from the retroreflector 2 is opposite to the traveling direction of the chief ray of the diffusive incident light beam that is incident on the retroreflector 2.

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

[0053] The traveling direction of the chief ray of the convergent reflected light beam reflected by the corner reflector array of the retroreflector 5 is not the opposite direction to the traveling direction of the chief ray of the diffusive incident light beam that is incident on the retroreflector 5. The normal direction component of the plate-shaped surface of the retroreflector 5 in the traveling direction of the chief ray of the diffusive incident light beam that is incident on the retroreflector 5 and the normal direction component of the plate-shaped surface of the retroreflector 5 in the traveling direction of the chief ray after being reflected by the retroreflector 5 and becoming a convergent reflected light beam, travel in a straight line, unchanged before and after reflection by the corner reflector array.

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

[0055] The resolution of the space-floating image formed by the light beams from the video output unit 10 depends not only on the resolution of the liquid crystal display panel 11, but also on the diameter D and pitch P (not shown) of the retroreflective portion of the retroreflector 5 shown in Figures 2E and 2F. 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 P is 300 μm, one pixel of the space-floating image will be equivalent to 300 μm. As a result, the effective resolution of the space-floating image will be reduced to about one-third.

[0056] Therefore, in order to make the resolution of the spatial floating image equivalent to that of the display device 10, it is desirable to make the diameter D and pitch P of the retroreflective portion close to one pixel of the liquid crystal display panel. On the other hand, to suppress the occurrence of moire due to 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. Furthermore, it is advisable to arrange the shape of the retroreflective portion so that none of its sides overlaps any of the sides of one pixel of the liquid crystal display panel.

[0057] The shape of the retroreflector (imaging optical plate) according to this embodiment is not limited to the above example. It may have various shapes that achieve retroreflection. Specifically, it may be a variety of cubic corner bodies, corner reflector arrays, slit mirror arrays, dihedral corner reflector arrays, polyhedral reflector arrays, or shapes in which a combination of these reflective surfaces is periodically arranged. Alternatively, capsule lens-type retroreflecting elements in which glass beads are periodically arranged may be provided on the surface of the retroreflector according to this embodiment. Since existing technology can be used for the detailed configuration of these retroreflecting elements, a detailed description will be omitted. Specifically, the technology disclosed in JP 2017-33005 A, JP 2019-133110 A, JP 2017-67933 A, WO 2009 / 131128 A, etc. may be used.

[0058] 2D, the image light emitted from the display device 10 may be in any polarization state, either S-polarized or P-polarized.

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

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

[0061] <<Block diagram of the internal configuration of the space floating image display device>>

[0062] 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.

[0063] 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, a microphone 1139, an image control unit 1160, a storage unit 1170, an imaging unit 1180, etc. In addition, the space-floating image display device 1000 may 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.

[0064] Each component of the space floating image display device 1000 is disposed in a housing 1190. Note that the imaging unit 1180 and the mid-air operation detection sensor 1351 shown in FIG.

[0065] 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.

[0066] The image display unit 1102 in Fig. 3 corresponds to the liquid crystal display panel 11 in Fig. 2A, 2B, and 2C. The light source 1105 in Fig. 3 corresponds to the light source device 13 in Fig. 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 Fig. 2A, 2B, and 2C.

[0067] 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.

[0068] 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 component 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 requiring 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.

[0069] 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. Various methods are possible for combining 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.

[0070] The aerial operation detection sensor 1351 is a sensor that detects an operation of 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.

[0071] Specific examples of the aerial operation detection sensor 1351 include a distance sensor that uses invisible light such as infrared light, an invisible light 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) sensor or an image sensor.

[0072] 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.

[0073] The aerial operation detection unit 1350 acquires a sensing signal from the aerial operation detection sensor 1351, and determines whether or not the finger of the user 230 has made contact with an object in the floating-in-space image 3 based on the sensing signal, 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.

[0074] 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 separate entities from the space-floating image display device 1000. When provided as separate entities 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.

[0075] Furthermore, 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, which does not have an aerial operation detection function, is used as the main body, and only the aerial operation detection function can be added as an option. Furthermore, 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 where 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.

[0076] 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, etc.

[0077] 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 that has not intruded into the intrusion detection plane (for example, a user's finger) is from the intrusion detection plane, or how close the object is to the intrusion detection plane.

[0078] 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 images captured by the multiple image capturing units 1180 and object depth information from the depth sensor. These pieces of information and various other information such as the distance between the object and the intrusion detection plane are then used for various display controls for the floating in space image 3.

[0079] Furthermore, without using the aerial operation detection sensor 1351 , the aerial 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 .

[0080] 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 the user 230 operating the space-floating image 3 and a range including the area surrounding the user 230.

[0081] The operation input unit 1107 is, for example, an operation button, a signal receiving unit such as a remote controller, or an infrared light receiving unit, and inputs signals for operations different from the aerial 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.

[0082] The video signal input unit 1131 is connected to an external video output device and inputs video data. Various digital video input interfaces are possible for the video signal input unit 1131. For example, the video signal input unit 1131 may be configured as a video input interface conforming to the HDMI (registered trademark) standard (High-Definition Multimedia Interface), a video input interface conforming to the DVI (Digital Visual Interface) standard, or a video input interface conforming to the DisplayPort standard.

[0083] 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 as an HDMI-standard audio input interface, 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 as a speaker.

[0084] 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. The microphone 1139 is a microphone that collects sounds around the space-floating image display device 1000, converts them into signals, and generates audio signals. The microphone may record a person's voice, such as a user's voice, and the control unit 1110, described later, may perform voice recognition processing on the generated audio signal to obtain text information from the audio signal.

[0085] The non-volatile memory 1108 stores various data used by the space floating image display device 1000. The data stored in the non-volatile memory 1108 includes, for example, data for various operations to be displayed on the space floating image 3, display icons, data 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.

[0086] 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.

[0087] 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, by an Ethernet-standard LAN interface. If the communication unit 1132 has a wireless communication interface, the interface may be configured, for example, by 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.

[0088] 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.

[0089] The storage unit 1170 is a storage device that records various types of information, such as video data, image data, and audio data. The storage unit 1170 may be 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, and audio data, may be recorded in advance in the storage unit 1170 at the time of product shipment. The storage unit 1170 may also record various types of information, such as video data, image data, and audio data, acquired from an external device, an external server, or the like via the communication unit 1132.

[0090] 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 display icons, objects for the user to operate, etc., displayed as the space floating image 3, are also recorded in the storage unit 1170.

[0091] Layout information of display icons, objects, etc. displayed as the spatial 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.

[0092] 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 referred to as 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 referred to as a video processing unit or an image processing unit. The video control unit 1160 controls video switching, such as determining which video signal to input to the video display unit 1102, between the video signal to be stored in the memory 1109 and the video signal (video data) input to the video signal input unit 1131, for example.

[0093] In addition, the image control unit 1160 may generate a superimposed image signal by superimposing the image signal to be stored in the memory 1109 and the image signal input from the image signal input unit 1131, and input the superimposed image signal to the image display unit 1102, thereby controlling the formation of a composite image as a floating image in space 3.

[0094] 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 that enlarges, reduces, or deforms the image, brightness adjustment processing that changes the brightness, contrast adjustment processing that changes the contrast curve of the image, and Retinex processing that decomposes the image into light components and changes the weighting of each component.

[0095] Furthermore, the video control unit 1160 may perform special effect video processing or the like on the video signal input to the video display unit 1102 to assist the aerial operation (touch operation) of the user 230. 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 or the image of the user 230 captured by the imaging unit 1180.

[0096] The attitude sensor 1113 is a sensor configured with a gravity sensor, an acceleration sensor, or a combination of these, and can detect the attitude in which the space-floating image display device 1000 is installed. Based on the attitude detection result of the attitude sensor 1113, the control unit 1110 may control the operation of each connected unit. For example, if an undesirable attitude is detected as the user's usage state, the control unit 1110 may perform control such that the image displayed on the image display unit 1102 is stopped and an error message is displayed to the user. Alternatively, if 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 orientation of the image displayed on the image display unit 1102 is rotated.

[0097] 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.

[0098] <Configuration Example of Space-Floating Image Display Device> Next, a configuration example of the space-floating image display device will be described. The layout of the components of the space-floating image display device according to this embodiment can be various depending on the usage form. Below, the layouts of each of Figs. 4A to 4M will be described. Note that in each of the examples 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.

[0099] 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 shown in 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 user's finger. 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.

[0100] 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. When the mid-air operation detection sensor 1351 is installed as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the user 230's finger. 4B , the aerial 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 that this configuration can improve the accuracy of touch detection.

[0101] 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. When the mid-air operation detection sensor 1351 is installed as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the user's 230 finger.

[0102] 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 installed as shown in the figure, it can detect the operation of the space-floating image 3 by the user 230's finger. 4D , the aerial 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 that this configuration can improve the accuracy of touch detection.

[0103] 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. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it is possible to detect the operation of the space-floating image 3 by the user's 230 finger.

[0104] 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 installed as shown in the figure, it can detect the operation of the space-floating image 3 by the user 230's finger.

[0105] 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. In the space-floating image display device 1000 shown in FIG. 4G, the surface on which the space-floating image 3 is formed is installed so that it faces the front of the device (toward the user 230). 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.

[0106] 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 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 floating feeling of the space floating image 3.

[0107] 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 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.

[0108] 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 in the window of the transparent plate 100B located on the back of the device (opposite the position where the user 230 views the space-floating image 3). The rest of the configuration is the same as that of the space-floating image display device of Fig. 4H, so repeated explanations will be omitted.

[0109] The opening and closing door 1410 of the space-floating image display device 1000 in FIG. 4I has, for example, a light blocking plate and is equipped with 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 (rear window) of the transparent plate 100B located at the back of the space-floating image display device 1000. The movement (sliding) and rotation of the light blocking plate by the opening and closing door 1410 may be electrically driven by a motor (not shown). The motor may be controlled by the control unit 1110 in FIG. 3. Note that the example in FIG. 4I discloses an example in which the opening and closing door 1410 has two light blocking plates. In contrast, the opening and closing door 1410 may have only one light blocking plate.

[0110] For example, if 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-shielding 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-shielding 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-shielding plate of the opening / closing door 1410.

[0111] 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 is possible to more suitably maintain the visibility of the space-floating image 3, even if the user 230 does not manually open or close the light blocking plate of the opening and closing door 1410.

[0112] Furthermore, the light blocking plate provided 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. Furthermore, if it is planned to use the rear window in an open state for a long period of time, the detachable light blocking plate can be left detached. The light blocking plate may be attached and detached using screws, a hook structure, or a fitting structure.

[0113] 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 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 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 visible to 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.

[0114] 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 arranging a transparent plate 100B made of glass or plastic on the rear side window, an electronically controlled transmittance variable device 1620 is arranged. The other configurations are the same as those of the space-floating image display device of Fig. 4H, so repeated explanations will be omitted. An example of the electronically controlled transmittance variable device 1620 is a liquid crystal shutter.

[0115] That is, the liquid crystal shutter can control the amount of light transmitted by controlling the voltage of the liquid crystal element sandwiched between two polarizing plates. Therefore, by controlling the liquid crystal shutter to increase the transmittance, the scenery through the rear window can be seen through the background of the space-floating image 3. 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 control the intermediate length, it can also be set to a transmittance of 50% or more. For example, the control unit 1110 can control the transmittance of the electronically controlled transmittance variable device 1620 in response to an operation input via the operation input unit 1107 of FIG. 3 . With this configuration, in cases where a view through the rear window is desired as the background of the space-floating image 3, but the view through the background rear window 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 variable device 1620.

[0116] In addition, 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 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 of 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.

[0117] In the above example, a liquid crystal shutter has been described as an example of the electronically controlled transmittance varying device 1620. However, electronic paper may be used as another example of the electronically controlled transmittance varying device 1620. The same effect as described above can be obtained when electronic paper is used. Furthermore, electronic paper consumes very little power to maintain a halftone state. Therefore, a space floating image display device with lower power consumption can be realized compared to when a liquid crystal shutter is used.

[0118] 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.

[0119] In the space-floating image display device 1000 of FIG. 4K, an image luminous flux 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, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2014-216761. Although the transmissive self-luminous image display device 1650 is not shown in FIG. 3, it may be configured to be connected to other processing units, such as the control unit 1110, as a component of the space-floating image display device 1000 of FIG. 3.

[0120] Here, if the transmissive self-luminous image 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 in the floating image 3, it is possible to provide the user 230 with a more effective surprise image experience.

[0121] Furthermore, if the interior 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 will be 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 will become 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 suddenly be displayed in the air as the space-floating image 3, thereby providing the user 230 with a more effective surprise video experience.

[0122] 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 light of the image light reflected by the polarization separation member 101B and absorbs polarized light that is 90° out of phase with the polarized light may be provided on the interior surface of the transmissive self-luminous image display device 1650 (the surface on which 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). While this does not have a significant effect on the image light that forms the space-floating image 3, it can significantly reduce the light that enters 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.

[0123] 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.

[0124] 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.

[0125] 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 from 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.

[0126] Fig. 4M is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 4M is provided with a second display device 1680 on the rear side as seen from the user relative to 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.

[0127] 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.

[0128] 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 separation member 101B. Therefore, in order for the image light of the second display device 1680 to more suitably pass through the polarization separation member 101B, it is desirable that the image light output from the second display device 1680 be polarized with a polarization in a vibration direction that the polarization separation member 101B more suitably transmits. In other words, it is desirable that the image light be polarized with a polarization 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.

[0129] 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, in the example of the space-floating image display device of FIG. 4M, it is possible to realize the space-floating image display device 1000 at a lower cost than the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L.

[0130] 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, there is a possibility that part of the image light output from the display device 1 will be reflected by the polarization separation member 101B and head toward the second display device 1680. This light (part of the image light) may be reflected again by the surface of the second display device 1680 and may be visually recognized by the user as stray light.

[0131] 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 present on the image output side inside the liquid crystal display. However, if a cover glass (cover glass on the image display surface side) is further provided on the output surface of the absorptive polarizer on the image output side inside the liquid crystal display, it is not possible to prevent stray light caused by reflection of the cover glass 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.

[0132] 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 user in relation to 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 three dimensions.

[0133] 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.

[0134] Next, Fig. 4N is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 4N is a space-floating image display device that employs the optical system of Fig. 2D. As with the examples of space-floating image display devices that employ the optical systems of Figs. 2A to 2C, an image is formed in the air as a space-floating image 3 by image light that has passed through a transparent member 100. Furthermore, using sensing light from an aerial operation detection sensor 1351 that is located on the back side of the transparent member 100 as seen from the user, it is possible to detect operation of the space-floating image 3 by the user's finger 9004.

[0135] 2A to 2C, and in the example of the space-floating image display device employing the optical system of Fig. 2D, the space-floating image 3 is formed in front of the transparent member 100, and the operation of the space-floating image 3 by the user's finger can be detected using the sensing light of the mid-air operation detection sensor 1351 arranged on the back side of the transparent member 100 as seen from the user. Therefore, the space-floating image display device employing the optical system of Fig. 2D has a different optical system from the space-floating image display device in which the optical system of Fig. 2A to 2C is arranged on the back side of the transparent member 100 as seen from the user.

[0136] However, from the user's perspective, the usability of the space-floating image display device employing the optical system of FIG. 2D is almost the same as that of the space-floating image display device employing the optical system of FIGS. 2A to 2C.

[0137] Next, Fig. 4O is a diagram showing an example of the configuration of a space-floating image display device. Fig. 4O is a diagram showing the configuration of the internal optical system of the space-floating image display device 1000 of Fig. 4N. The space-floating image display device 1000 shown in Fig. 4O is equipped with an optical system corresponding to the optical system of Fig. 2D. The space-floating image display device 1000 shown in Fig. 4O is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward.

[0138] 4O, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. When the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0139] Here, the configuration of Fig. 4O will be compared with the configuration of Fig. 4A to confirm the differences. In Fig. 4A, the display device 1 and the space-floating image 3 are in a plane-symmetrical relationship with respect to the plane of the polarization separation member 101. In contrast, in Fig. 4O, the display device 1 and the space-floating image 3 are in a plane-symmetrical relationship with respect to the plane of the retroreflector 5. Furthermore, the configuration of Fig. 4A includes the retroreflector 2 and the λ / 4 plate 21, but these are not present in Fig. 4O. Furthermore, while the presence of the absorbing polarizer 12 is more preferable in Fig. 4A, the absorbing polarizer 12 is not particularly necessary in Fig. 4O.

[0140] That is, to replace the optical system of FIG. 2A in the configuration of FIG. 4A with the optical system of FIG. 2D and to replace it with the configuration of FIG. 4O, the following can be done. That is, the polarization separation member 101 in the configuration of FIG. 4A is replaced with the retroreflector 5, and the retroreflector 2 and the λ / 4 plate 21 are removed from the configuration of FIG. 4A. The absorptive polarizer 12 is optional. By performing a replacement based on this idea, the optical system of FIGS. 2A to 2C mounted in the configuration of the space-floating image display device of FIGS. 4A to 4G can be replaced with the optical system of FIG. 2D, and the space-floating image display device can be replaced with the optical system of FIG. 2D. In this case, the polarization separation member 101 in FIGS. 4A and 4B is replaced with the retroreflector 5, and the polarization separation member 101B in FIGS. 4C to 4G is replaced with the retroreflector 5.

[0141] In this way, it is possible to realize a space-floating image display device in which the optical system in the configuration of the space-floating image display device of Figures 4A to 4G is replaced with the optical system of Figure 2D. Even in these space-floating image display devices in which the optical system of Figure 2D is replaced, it is possible to realize a space-floating image display device that is almost as easy to use as the space-floating image display device of Figures 4A to 4G.

[0142] <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 the light source of the image display element 11. Fig. 5 shows the light source device 13 together with the liquid crystal display panel as an exploded perspective view.

[0143] 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 (linearity) 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).

[0144] 5 also shows a configuration including a liquid crystal display panel 11 constituting the display device 1, a light redirection panel 54 for controlling the directional characteristics of the light beam emitted from the light source device 13, and, if necessary, a narrow-angle diffuser (not shown). 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 the desired image to be projected as highly directional (linear) light of a specific polarization via the light redirection panel 54 toward the retroreflector 2, where it is reflected by the retroreflector 2 and transmitted to the eyes of a monitor 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.

[0145] <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, formed of, for example, plastic, and contains LED elements 201 and a light guide 203 therein. As shown in FIG. 5 and other figures, the end surface of the light guide 203 has a lens-like 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-like shape gradually reduces 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. Furthermore, 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 of the case of the light source device 13 (the left end surface in this example). A heat sink, which is a member for cooling the heat generated by the LED elements and the control circuit, may be attached to the outer surface of the LED board 202 .

[0146] Furthermore, a frame (not shown) for the liquid crystal display panel is attached to the top surface of the case of the light source device 13. The frame includes the liquid crystal display panel 11, which is attached to the frame, and a flexible printed circuit (FPC) (not shown) electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is an image display element, generates a display image by modulating the intensity of transmitted light 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.

[0147] 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.

[0148] 6 and 7 are cross-sectional views, and only one of the 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 on the end surface of the light guide and the LED element are attached while maintaining a predetermined positional relationship.

[0149] Each light guide 203 is formed of a translucent resin such as acrylic. The LED light-receiving surface at the end of the light guide 203 has a cone-shaped outer periphery obtained by rotating a parabolic cross section, and the top of the light guide 203 has a concave portion with a convex portion (i.e., a convex lens surface) formed in the center, and the center of the flat portion has 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 the 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 of the light emitted from the LED element toward the periphery within the parabolic shape, or a reflective surface is formed.

[0150] 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 203 a) so that the LED elements 201 on the surface are positioned in the center of the recessed portion described above.

[0151] With 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 utilization efficiency of the generated light.

[0152] As described above, the light source device 13 is configured by attaching a light source unit having a plurality of LED elements 201 arranged as light sources 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 as shown by the arrow (in a direction parallel to the drawing), 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.

[0153] 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) that 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.

[0154] 6 is a cross-sectional layout diagram illustrating the configuration and operation of the light source of this embodiment that performs polarization conversion in light source device 13 including the above-mentioned light guide 203 and LED element 201. In Fig. 6, light source device 13 is composed of light guide 203 formed of, for example, plastic or the like and 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 thereof is attached liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0155] 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 polarized wave (e.g., P wave) 212 of the natural light beam 210 emitted from the LED element 201. The reflected light is reflected again by a 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, and the reflected light beam is reflected by the reflective sheet 205 and passes through it twice to convert the reflected light beam from P polarized light to S polarized light, 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 image, a floating image in space, can be obtained.

[0156] 7 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in a light source device 13 including a light guide 203 and an LED element 201, similar to Fig. 6. The light source device 13 is similarly configured with a light guide 203 formed of, for example, plastic, on the surface of which or inside which a light beam direction conversion means 204 is provided, an LED element 201 as a light source, a reflective sheet 205, a retardation plate 206, a lenticular lens, etc. A liquid crystal display panel 11 is attached to the top surface of the light source device 13 as an image display element, and the panel has polarizing plates on the light source light entrance surface and the image light exit surface.

[0157] A film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence 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. That is, in the example of FIG. 7 , the selective reflection characteristics of the reflective polarizing plate 49 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 the reflected light beam 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.

[0158] 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. Therefore, 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.

[0159] <Display Device Example 2> Figure 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 are attached to one side of the case of the light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer surface of the LED board.

[0160] The liquid crystal display panel frame attached to the top surface of the case is configured to have attached thereto the 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.

[0161] <Display Device Example 3> Next, another example of the specific configuration of the display device 1 (Display Device Example 3) 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 reflective 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 polarized other than the specific polarization (e.g., S-polarized light) is reflected by the reflective polarizer 49 and directed again toward the reflective light guide 304.

[0162] 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 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.

[0163] At this time, the light that re-enters the reflective polarizing plate 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 polarizing plate 49. Therefore, the light whose polarization has been converted passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that, with regard to the polarization design related to the polarization conversion, the polarization may be configured in reverse from the above explanation (S-polarized light and P-polarized light may be reversed).

[0164] 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, because 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.

[0165] Each collimator 18 is formed of a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer circumferential 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 surface (the side opposite the apex). The parabolic surface forming the cone-shaped outer circumferential 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, or a reflective surface is formed therein.

[0166] The LEDs are arranged at predetermined positions on the surface of the circuit board, that is, the LED board 102. The LED board 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface are positioned at the center of the apex of the convex cone shape (or in the recess if the apex has a recess).

[0167] With this configuration, the collimator 18 focuses light emitted from the LED, particularly 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.

[0168] Furthermore, the light converted into approximately parallel light by the collimator 18 shown in FIG. 9 is reflected by the reflective light guide 304. Of this light, light of a specific polarization passes through the reflective polarizer 49 due to the action of the reflective polarizer 49, while light of the other polarization reflected by the action of the reflective polarizer 49 passes through the light guide 304 again. The light is reflected by the reflector 271 located opposite the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarized and converted by passing twice through the λ / 4 plate 270, which is a retardation plate. The light reflected by the reflector 271 passes through the light guide 304 again and enters the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarized and converted, it passes 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 used, 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. Adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 for each design can improve the uniformity of the light incident on the liquid crystal display panel 11.

[0169] 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.

[0170] <Display Device Example 4> Another example (Display Device Example 4) 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 a configuration example in which a diffusion sheet is used instead of the reflective light guide 304 in the light source device of Display Device Example 3. Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) that convert 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).

[0171] The optical sheet may be a single sheet instead of a two-sheet configuration. In 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 the liquid crystal display panel 11 is uniform. In other words, the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of light guides.

[0172] 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 , the 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 from the light source LED, and the transmitted light enters the liquid crystal display panel 11. The reflective polarizing plate 49 reflects S-polarized light from the light source LED, and the reflected light passes through the retardation plate 270 shown in FIG. 10 . The light that passes through the retardation plate 270 is reflected by the reflector 271. The light reflected by the reflector 271 passes through the retardation plate 270 again and is converted to P-polarized light. The polarization-converted light passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11.

[0173] 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 may be used. 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.

[0174] In a typical TV device, the light emitted from the liquid crystal display 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 liquid crystal display panel of this embodiment are, for example, 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, this is 1 / 5 of the 62 degrees of a typical TV device. Similarly, the vertical viewing angle is set asymmetrically 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 being more than 50 times higher.

[0175] Furthermore, assuming the viewing angle characteristics shown in Example 2 of Figure 12, if the viewing angle at which brightness is 50% of that at a front view (angle of 0 degrees) is set to 5 degrees, this is 1 / 12 of the 62 degrees of devices used for general TV applications. Similarly, the vertical viewing angle is set equal at the top and bottom, and the reflection angle and area of ​​the reflective surface of the reflective light guide are optimized to keep the viewing angle to about 1 / 12 of that of devices used for general TV applications. 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 higher.

[0176] 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 aimed at bright outdoor areas.

[0177] When using a large LCD panel, the 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-inch panel in portrait orientation and the monitoring distance is 0.8 m, a convergence angle of 10 degrees will allow the image light from the four corners of the screen to be effectively directed toward the observer.

[0178] Similarly, when monitoring with a 15-inch panel in portrait orientation and a monitoring distance of 0.8 m, a convergence angle of 7 degrees will allow the image light from the four corners of the screen to be effectively directed towards the monitor. As described above, depending on the size of the liquid crystal display 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.

[0179] 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 spatially floating image is displayed indoors or outdoors via a transparent member 100.

[0180] 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.

[0181] <Example of Image Display Processing in Space-Floating Image Display Device> Next, an example of a problem solved by the image processing of this embodiment will be described with reference to Fig. 13A. In the space-floating image display device 1000, when the far side of the space-floating image 3 as seen from the user is inside the housing of the space-floating image display device 1000 and is sufficiently dark, the user will visually recognize that the background of the space-floating image 3 is black.

[0182] Here, an example of displaying a character "panda" 1525 in a floating-in-space image 3 will be described with reference to Fig. 13A. First, for an image including a pixel region for drawing the image of the character "panda" 1525 and a transparent information region 1520 that is a background image, as shown in Fig. 13A(1), the image control unit 1160 in Fig. 3 distinguishes and recognizes the pixel region for drawing the image of the character "panda" 1525 from the transparent information region 1520 that is a background image.

[0183] A method for distinguishing and recognizing the character image from the background image is, for example, to configure the image processing of the video control unit 1160 so that the background image layer and the character image layer in front of the background image layer can be processed as separate layers, and the character image and background image can be distinguished and recognized based on the superimposition relationship when these layers are combined.

[0184] Here, the image control unit 1160 recognizes black pixels that depict objects such as character images and transparent information pixels as different information. However, it is assumed that both the black pixels that depict objects and the transparent information pixels have a luminance of 0. In this case, when the Space Floating Image 3 is displayed, there is no difference in luminance between the pixels that depict black in the image of the character "panda" 1525 and the pixels of the transparent information region 1520, which is the background image. Therefore, in the Space Floating Image 3, as shown in FIG. 13A (2), neither the pixels that depict black in the image of the character "panda" 1525 nor the pixels of the transparent information region 1520 have luminance, and they are visually perceived by the user as the same optically black space. In other words, the black portions of the image of the character "panda" 1525, which is an object, blend into the background, and only the non-black portions of the character "panda" 1525 are perceived as floating in the display region of the Space Floating Image 3.

[0185] An example of image processing according to this embodiment will be described with reference to FIG. 13B. FIG. 13B is a diagram illustrating an example of image processing that more effectively resolves the issue of the black image region of the object blending into the background, as described in FIG. 13A. In FIGS. 13B(1) and 13B(2), the upper side shows the display state of the floating-in-space image 3, and the lower side shows the input / output characteristics of the image processing of the image of the object. Note that the image of the object (character "panda" 1525) and the corresponding data may be read from the storage unit 1170 or memory 1109 in FIG. 3, or may be input from the video signal input unit 1131, or may be acquired via the communication unit 1132.

[0186] In the state shown in Figure 13B(1), the input / output characteristics of the image processing of the object image are in a linear state with no particular adjustment. In this case, the display state is the same as in Figure 13A(2), and the black image area of ​​the object blends into the background. In contrast, in Figure 13B(2), the video control unit 1160 of this embodiment adjusts the input / output characteristics of the image processing of the image of the object (character "panda" 1525) to the input / output characteristics shown in the lower row.

[0187] That is, the video control unit 1160 performs image processing with input / output characteristics on the image of the object (character "panda" 1525), which has a characteristic of converting pixels in low-brightness areas of the input image into output pixels with increased brightness values. After the image of the object (character "panda" 1525) has been subjected to the image processing with input / output characteristics, a video including the image of the object (character "panda" 1525) is input to the display device 1 and displayed. Then, as shown in the upper part of FIG. 13B (2), the display state of the floating in space image 3 is such that the brightness of pixel areas depicting black in the image of the character "panda" 1525 increases. This allows the user to distinguish the areas depicting black among the areas depicting the image of the character "panda" 1525 without them blending into the black background, making it possible to display the object more appropriately.

[0188] 13B(2), the area displaying the image of the object character "panda" 1525 can be distinguished from the black background inside the housing of the space-floating image display device 1000 through the window, improving the visibility of the object. Therefore, for example, even if the object includes pixels with a brightness value of 0 among the pixels constituting the object before the image processing (i.e., at the time when the image of the object and the corresponding data are read from the storage unit 1170 or memory 1109 in FIG. 3, or at the time when the image of the object is input from the video signal input unit 1131, or at the time when the data of the object is acquired via the communication unit 1132, etc.), the image processing of the input / output characteristics by the video control unit 1160 converts the object into an object with increased brightness values ​​of pixels in low-brightness areas, and then the object is displayed on the display device 1 and converted into a space-floating image 3 by the optical system of the space-floating image display device 1000.

[0189] That is, the pixels that make up the object after image processing of the input / output characteristics are converted to a state in which they do not include pixels with a brightness value of 0, and then they are displayed on the display device 1 and converted into a floating image 3 by the optical system of the floating image display device 1000.

[0190] In the image processing of Figure 13B(2), a method for applying image processing with the input / output characteristics of Figure 13B(2) only to the image area of ​​the object (character "panda" 1525) is, for example, to configure the image processing of the video control unit 1160 so that the background image layer and the layer of the character image in front of the background image layer can be processed as separate layers, and the image processing with the input / output characteristics of Figure 13B(2) is applied to the character image layer while not applying this image processing to the background image layer.

[0191] Then, by combining these layers, image processing with a characteristic of raising the low-brightness areas of the input image is performed only on the character image, as shown in Fig. 13B (2). Alternatively, after the character image layer and background image layer are combined, image processing with the input / output characteristics of Fig. 13B (2) may be performed only on the character image area.

[0192] Furthermore, the input / output image characteristics used in the image processing for enhancing low-luminance regions of the input / output characteristics for the input image are not limited to the example shown in FIG. 13B(2). Any image processing for enhancing low luminance may be used, including so-called brightness adjustment. Alternatively, image processing for improving visibility by controlling the gain that changes the weighting of Retinex processing, as disclosed in International Publication WO 2014 / 162533, may be performed.

[0193] According to the image processing of FIG. 13B(2) described above, it is possible to make the user aware of areas where black is drawn among areas where images of characters, objects, etc. are drawn without blending into the black background, thereby realizing a more suitable display.

[0194] 13A and 13B, the problems and more suitable image processing were explained using a space-floating image display device in which the background appears black (for example, the space-floating image display device 1000 in FIGS. 4A to 4G, or the space-floating image display device 1000 in a state where the rear side window is shaded in FIGS. 4I and 4J). However, this image processing is also effective for devices other than these space-floating image display devices.

[0195] Specifically, in the space-floating image display device 1000 of Fig. 4H and the space-floating image display device 1000 in Fig. 4I and Fig. 4J where the rear window is not shaded, the background of the space-floating image 3 is not black, but the scenery behind the space-floating image display device 1000 through the window. In this case, the problems explained in Fig. 13A and Fig. 13B also exist.

[0196] That is, the part of the image of the character "panda" 1525, which is an object, that is drawn in black will blend into the scenery behind the space-floating image display device 1000 through the window. In this case, by using the image processing of Fig. 13B (2), the part of the image of the character "panda" 1525, which is an object, that is drawn in black will be recognized as being distinct from the scenery behind the space-floating image display device 1000 through the window, improving the visibility of the object.

[0197] That is, by using the image processing of FIG. 13B(2), the area displaying the image of the character "panda" 1525, which is an object, can be recognized as distinct from the scenery behind the space floating image display device 1000 through the window, and it can be more easily recognized that the character "panda" 1525, which is the object, is in front of the scenery, improving the visibility of the object.

[0198] 4K, 4L, and 4M, as described above, when another image (such as an image from the transmissive self-luminous image display device 1650 or an image from the second display device 1680) is displayed at a position different in depth from the space-floating image 3, the background of the space-floating image 3 is not black, but the other image. In this case, the problems described in FIGS. 13A and 13B also exist.

[0199] That is, the part of the image of the character "panda" 1525, which is an object, that is drawn in black will blend into the other image that is displayed at a different depth from the floating image in space 3. In this case as well, by using the image processing of Fig. 13B(2), the part of the image of the character "panda" 1525, which is an object, that is drawn in black will be recognizable as being distinct from the other image, improving the visibility of the object.

[0200] In other words, by using the image processing of Figure 13B (2), the area displaying the image of the object character "panda" 1525 can be recognized as distinct from the other image, and it can be more easily recognized that the object character "panda" 1525 is in front of the other image, improving the visibility of the object.

[0201] An example of the image display process of this embodiment will be described with reference to Fig. 13C. Fig. 13C shows an example of the image display process of this embodiment, in which the space floating image 3 and a second image 2050, which is another image, are simultaneously displayed. The second image 2050 may correspond to the image displayed by the transmissive self-luminous image display device 1650 of Fig. 4K or 4L. The second image 2050 may also correspond to the image displayed by the second display device 1680 of Fig. 4M.

[0202] That is, the example of the image display in Fig. 13C shows a specific example of the image display examples of the space-floating image display device 1000 in Figs. 4K, 4L, and 4M. In the example of this figure, a bear character is displayed in space-floating image 3. Areas other than the bear character in space-floating image 3 are displayed in black, and become transparent as a space-floating image. In addition, the second image 2050 is a background image in which a plain, a mountain, and a sun are drawn.

[0203] 13C , the floating-in-space image 3 and the second image 2050 are displayed at different depth positions. When the user 230 views the two images, the floating-in-space image 3 and the second image 2050, in the line of sight of the arrow 2040, the user 230 can view the two images superimposed on each other. Specifically, the bear character of the floating-in-space image 3 appears superimposed in front of the background of plains, mountains, and the sun depicted in the second image 2050.

[0204] Here, since the space floating image 3 is formed as a real image in the air, when the user 230 moves their viewpoint slightly, they can recognize the depth of the space floating image 3 and the second image 2050 due to parallax. Therefore, the user 230 can get a stronger sense of floating in space from the space floating image 3 while viewing the two images in an overlapping state.

[0205] An example of the image display process of this embodiment will be described with reference to Fig. 13D. Fig. 13D(1) is a diagram of the floating in space image 3, from the example of image display of this embodiment in Fig. 13C, as seen from the line of sight of the user 230. Here, a bear character is displayed in the floating in space image 3. The area other than the bear character in the floating in space image 3 is displayed in black, and the floating in space image is transparent.

[0206] 13D(2) is a diagram showing the second image 2050 in the example of the video display of this embodiment shown in FIG. 13C as viewed from the line of sight of the user 230. In the example shown in this figure, the second image 2050 is a background image in which a plain, a mountain, and a sun are depicted.

[0207] 13D(3) is a diagram showing the state in which the second image 2050 and the floating in space image 3 appear superimposed in the line of sight of the user 230, among the example of image display of this embodiment in Fig. 13C. Specifically, the bear character of the floating in space image 3 appears superimposed in front of the background of plains, mountains, and the sun depicted in the second image 2050.

[0208] Here, when the space-floating image 3 and the second image 2050 are displayed simultaneously, it is desirable to pay attention to the balance of brightness between the two images in order to more favorably ensure the visibility of the space-floating image 3. If the second image 2050 is too bright compared to the brightness of the space-floating image 3, the displayed image of the space-floating image 3 will be transparent, and the second image 2050, which is the background, will be strongly visible through it.

[0209] Therefore, the output of the light source of the spatially floating image 3 and the display image brightness of the display device 1, and the output of the light source of the display device displaying the second image 2050 and the display image brightness of the display device should be set so that at least the brightness per unit area of ​​the spatially floating image 3 at the display position of the spatially floating image 3 is greater than the brightness per unit area of ​​the image light that reaches the display position of the spatially floating image 3 from the second image 2050.

[0210] Note that, since this condition only needs to be satisfied when the space-floating image 3 and the second image 2050 are displayed simultaneously, when switching from the first display mode in which the space-floating image 3 is not displayed and only the second image 2050 is displayed to the second display mode in which the space-floating image 3 and the second image 2050 are displayed simultaneously, control may be performed to reduce the brightness of the second image 2050 by lowering the output of the light source of the display device that displays the second image 2050 and / or the display image brightness of the display device. These controls may be realized by the control unit 1110 in Fig. 3 controlling the display device 1 and the display device that displays the second image 2050 (the transmissive self-luminous image display device 1650 in Fig. 4K or 4L or the second display device 1680 in Fig. 4M).

[0211] Note that when switching from the above-described first display mode to the above-described second display mode, if control is performed to reduce the brightness of second image 2050, the brightness may be reduced uniformly across the entire screen of second image 2050. Alternatively, instead of reducing the brightness uniformly across the entire screen of second image 2050, the brightness reduction effect may be greatest in the portion where an object is displayed in space-floating image 3, and the brightness reduction effect may be gradually weakened around that portion. In other words, the visibility of space-floating image 3 can be sufficiently ensured by reducing the brightness of second image 2050 only in the portion where space-floating image 3 is visually recognized as being superimposed on second image 2050.

[0212] Here, since the space floating image 3 and the second image 2050 are displayed at positions with different depths, when the user 230 slightly changes their viewpoint, the parallax causes a change in the superimposed position of the space floating image 3 relative to the second image 2050. Therefore, when switching from the above-mentioned first display mode to the above-mentioned second display mode, if the brightness is to be reduced unevenly across the entire screen of the second image 2050, it is not desirable to reduce the brightness sharply based on the outline of the object displayed in the space floating image 3, and it is desirable to perform gradation processing of the brightness reduction effect, which changes the brightness reduction effect in stages depending on the position as described above.

[0213] In addition, in the space floating image display device 1000 where the position of the object displayed in the space floating image 3 is approximately at the center of the space floating image 3, the position where the brightness reduction effect of the gradation processing of the brightness reduction effect is greatest can be set to the center position of the space floating image 3.

[0214] According to the image display process of this embodiment described above, the user 230 can view the space floating image 3 and the second image 2050 more favorably.

[0215] Note that when displaying the space-floating image 3, control may be performed so as not to display the second image 2050. Since not displaying the second image 2050 increases the visibility of the space-floating image 3, this is suitable for applications such as the space-floating image display device 1000 in which the user must be able to reliably view the space-floating image 3 when it is displayed.

[0216] <Example 2> As Example 2 of the present invention, an example of another configuration example of a space-floating image display device will be described. Note that the space-floating image display device according to this example is obtained by changing the optical system stored in the space-floating image display device described in Example 1 to the optical system shown in Figure 14 (1) or Figure 14 (2). In this example, differences from Example 1 will be described, and repeated explanations of the same configuration as Example 1 will be omitted. Note that in the following description of this example, the predetermined polarized light and the other polarized light are polarized waves whose phases differ by 90° from each other.

[0217] Fig. 14(1) shows an example of an optical system and optical path according to this embodiment. The optical system shown in Fig. 14(1) is configured such that the display device 1 is closer to the polarization separation member 101B in the optical system of Fig. 2C, making the entire optical system more compact. In Fig. 14(1), components that are assigned the same reference numerals as those in Fig. 2C will not be described in detail again.

[0218] 14(1), similar to Fig. 2C, image light of a predetermined polarized light (P-polarized light in the figure) emitted from display device 1 travels in a direction perpendicular to the image display surface of display device 1. Here, similar to Fig. 2C, polarization separation member 101B selectively transmits the predetermined polarized light (P-polarized light in the figure) emitted from display device 1 and reflects the other polarized light (S-polarized light in the figure).

[0219] Therefore, image light of a predetermined polarization (P-polarized light in the figure) traveling in the vertical direction from the image display surface of the display device 1 passes through the polarization separation member 101B and reaches the retroreflector 2 to which the λ / 4 plate 21 is attached. The image light that is retroreflected by the retroreflector 2 and travels again toward the polarization separation member 101B has passed through the λ / 4 plate 21 twice, and is converted from the predetermined polarization (P-polarized light in the figure) at the time of emission from the display device 1 to the other polarization (S-polarized light in the figure). The image light that travels again toward the polarization separation member 101B is the other polarization (S-polarized light in the figure), and is therefore reflected by the polarization separation member 101B toward the position where the user should be. The traveling direction of the image reflected by the polarization separation member 101B is determined based on the angle at which the polarization separation member 101B is disposed.

[0220] In the example of Figure 14 (1), the image light traveling toward the polarization separation member 101B is reflected at a right angle by the polarization separation member 101B and travels as shown in the figure. The image light reflected by the polarization separation member 101B forms a floating image 3A in space. The floating image 3A can be viewed by the user from the direction of arrow A.

[0221] Here, due to the characteristics of retroreflection by the retroreflector 2, the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 is equal to the optical path length of the image light emitted from the retroreflector 2 to reach the position where the space floating image 3A is formed. This relationship determines the position where the space floating image 3A is formed in the traveling direction of the image light reflected by the polarization separating member 101B.

[0222] In the example of Figure 14(1), the display device 1, the polarization separating member 101B, and the retroreflector 2 are arranged closer than in the example of Figure 2C. This allows the entire optical system to be configured more compactly. However, the amount by which the space-floating image 3A protrudes from the optical system of Figure 14(1) is not very large. For example, as an indicator of the amount by which the space-floating image 3A protrudes from the optical system, the figure shows the distance from the position where the central light beam of the image light is reflected by the polarization separating member 101B to the position where the image light forms the space-floating image 3A (L1 in the example of Figure 14(1)).

[0223] 14(1), the characteristics of P-polarized light and S-polarized light may be interchanged. Specifically, the predetermined polarization of the image light emitted from the display device 1 may be S-polarized light, and the characteristics of P-polarized light and S-polarized light may be interchanged with respect to the reflection characteristics of the polarization separation member 101B. In this case, the P-polarized light and S-polarized light shown in the figure are both reversed, but the optical design, such as the optical path, can be realized in exactly the same way.

[0224] Next, Fig. 14(2) shows another example of an optical system and an optical path according to this embodiment. The optical system of Fig. 14(2) is a modified version of the optical system of Fig. 14(1) in order to increase the amount of the floating image projecting from the optical system while realizing the same compactness as the optical system of Fig. 14(1). In Fig. 14(2), the components with the same reference numerals as Fig. 14(1) will not be described in detail again.

[0225] 14(2), as in FIG. 14(1), image light of a predetermined polarized light (P-polarized light in the figure) emitted from display device 1 travels in a direction perpendicular to the image display surface of display device 1. Here, the polarization characteristics of polarization separation member 101B are arranged 90 degrees differently from those in FIG. 14(1). Image light of a predetermined polarized light (P-polarized light in the figure) traveling in a direction perpendicular to the image display surface of display device 1 passes through polarization separation member 101B.

[0226] 14(1), the image light passing through the polarization separation member 101B is not faced with the retroreflector 2 having the λ / 4 plate 21 attached thereto, but with the specular reflector 4 having the λ / 4 plate 21B attached thereto. Here, the reflection at the specular reflector 4 is specular reflection (also called regular reflection), not retroreflection.

[0227] Therefore, the image light that has passed through polarization separation member 101B is specularly reflected by specular reflector 4 to which λ / 4 plate 21B is attached. The image light that has been specularly reflected by specular reflector 4 and travels again toward polarization separation member 101B has been converted from the predetermined polarization (P-polarized in the figure) at the time of emission from display device 1 to the other polarization (S-polarized in the figure) by having passed through λ / 4 plate 21 twice. The image light that has traveled again toward polarization separation member 101B is the other polarization (S-polarized in the figure), and is therefore reflected by polarization separation member 101B.

[0228] Here, because the orientation of the polarization separation member 101B in Figure 14(2) is different from that in Figure 14(1), the image light reflected by the polarization separation member 101B travels in the opposite direction from the position where the user should be. A retroreflector 2 with a λ / 4 plate 21C attached is disposed at the destination of the image light reflected by the polarization separation member 101B. The image light is retroreflected by the retroreflector 2. The image light that is retroreflected by the retroreflector 2 and travels again toward the polarization separation member 101B has been converted from the other polarized light (S-polarized light in the figure) to the specified polarized light (P-polarized light in the figure) by passing through the λ / 4 plate 21C twice.

[0229] The image light that travels back toward the polarization separation member 101B is of a predetermined polarization (P polarization in the figure), so it passes through the polarization separation member 101B and continues toward the location where the user should be. The image light that has passed through the polarization separation member 101B forms a floating image 3B in space. The floating image 3B can be easily viewed by the user from the direction of arrow A.

[0230] 14(2), as in the case of Fig. 14(1), due to the characteristics of retroreflection by the retroreflector 2, the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 is equal to the optical path length of the image light emitted from the retroreflector 2 to reach the formation position of the space floating image 3B. This relationship determines the formation position of the space floating image 3B in the traveling direction of the image light transmitted through the polarization separation member 101B.

[0231] 14(2), the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 is longer than the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2 in FIG. 14(1). This is because in the optical system of FIG. 14(2), an optical path going back and forth between the polarization separation member 101B and the specular reflector 4, which does not exist in the optical system of FIG. 14(1), is added to the optical path length of the image light emitted from the display device 1 to reach the retroreflector 2.

[0232] As a result, in the optical system of Figure 14(2), the distance from the position where the central ray of the image light passes through the polarization separation member 101B to the position where the image light forms the space-floating image 3B (L2 in the example of Figure 14(2)) is significantly longer than the distance from the position where the central ray of the image light is reflected by the polarization separation member 101B to the position where the image light forms the space-floating image 3A (L1 in the example of Figure 14(1)) in the optical system of Figure 14(1).

[0233] 14(2), the characteristics of P-polarized light and S-polarized light may be interchanged. Specifically, the predetermined polarization of the image light emitted from the display device 1 may be S-polarized light, and the characteristics of P-polarized light and S-polarized light may be interchanged with respect to the reflection characteristics of the polarization separation member 101B. In this case, the P-polarized light and S-polarized light shown in the figure are both reversed, but the optical design, such as the optical path, can be realized in exactly the same way.

[0234] As described above, according to the optical systems of Fig. 14(1) and Fig. 14(2) in the second embodiment of the present invention, a more compact optical system can be realized. In particular, according to the optical system of Fig. 14(2), it is possible to increase the amount of the floating image projecting from the optical system, despite the more compact optical system.

[0235] In addition, when the optical system of Fig. 14(1) or Fig. 14(2) is incorporated into a space-floating image display device, it can be realized by replacing the optical system in the space-floating image display device described in Example 1 with the optical system of Fig. 14(1) or Fig. 14(2). Specifically, the optical system of Fig. 14(1) may be replaced with the optical system of the space-floating image display device of Fig. 4E, Fig. 4F, Fig. 4G, Fig. 4H, Fig. 4I, Fig. 4J, Fig. 4K, Fig. 4L, or Fig. 4M. In this case, since the optical system becomes compact, it is possible to make the housing of the space-floating image display device of each figure smaller.

[0236] Specifically, the optical system of Fig. 14(2) may be replaced with the optical system of the space-floating image display device of Fig. 4E, Fig. 4F, Fig. 4G, Fig. 4K, or Fig. 4L. In this case, it is possible to increase the amount of the space-floating image projecting from the optical system. Also, since the optical system becomes compact, it is possible to make the housing of the space-floating image display device of each figure smaller.

[0237] <Example 3> As Example 3 of the present invention, an example of another configuration example of the space floating image display device will be described. Note that the space floating image display device according to this example is one in which the optical system stored in the space floating image display device explained in Example 1 is changed to the optical system shown in Figures 15, 20, and 21. In this example, differences from Example 1 will be explained, and repeated explanations of the same configuration as Example 1 will be omitted.

[0238] In the description of the present embodiment, an image floating in space is expressed by the term "space-floating image." Instead of this term, it is also acceptable to use terms such as "aerial image," "spatial image," "floating-in-the-air image," "space-floating optical image of displayed image," and "space-floating optical image of displayed image." The term "space-floating image," which is primarily used in the description of the present embodiment, is used as a representative example of these terms. Furthermore, in the description of the present embodiment, in the case of a configuration example in which it is more appropriate to express "image" display rather than "image" display, the image floating in space is expressed by the term "space-floating image." Instead of this term, it is also acceptable to use terms such as "aerial image," "spatial image," "floating-in-the-air image," "space-floating optical image of displayed image," and "space-floating optical image of displayed image." The term "space-floating image" is used as a representative example of these terms. In the description of the present embodiment, it is also acceptable to use terms such as "image," "space-floating image," "floating-in-the-air image," "space-floating optical image of displayed image," and "space-floating image."

[0239] The display device and display element in the description of this embodiment are sources for displaying videos and images, and may therefore be referred to as video sources or image sources.

[0240] <Another Configuration Example 4 of the Optical System of the Space-Floating Image Display Device> Figure 15 shows an example of the configuration of the main parts of a floating image display device 1000 according to Example 3 of the present invention. The display device 1 is configured with a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 is configured with a liquid crystal display panel of a selected size, from a small one with a screen size of about 5 inches to a large one exceeding 80 inches. The image light from the liquid crystal display panel 11 is reflected toward the retroreflective member 2 by a polarization separation member 101, such as a reflective polarizer.

[0241] A λ / 4 plate 21 is provided on the light incident / exit surface (retroreflective surface) of the retroreflective member 2, and polarization conversion is performed by passing the image light twice through the λ / 4 plate 21, i.e., converting a specific polarized wave (one polarized wave) into the other polarized wave. As a result, the other polarized wave after polarization conversion is transmitted through the polarization separation member 101, and a floating-in-the-air image 3, which is a real image, is formed and displayed outside the transparent member 100.

[0242] The floating-in-the-air image display device 1000 shown in FIG. 15 is equivalent to the floating-in-the-air image display device shown in FIG. 2A(1) in the above configuration. However, the floating-in-the-air image display device shown in FIG. 15 has a different configuration from the floating-in-the-air image display device shown in FIG. 2A(1) in that a decorative printed sheet (decorative printed layer) 115 is disposed on the top of the polarization separating member 101 and the transparent member 100. As shown in FIG. 15, the transparent member 100 is disposed on the light exit surface of the polarization separating member 101, and the decorative printed sheet 115 is disposed on the light exit surface of the transparent member 100. Note that, as will be described later, the decorative printed sheet 115 is not limited to being disposed on the top of the transparent member 100 (the side closer to the floating-in-the-air image 3; the light exit side), but may also be disposed below the transparent member 100 (the side farther from the floating-in-the-air image 3; the light entrance side).

[0243] Here, the decorative printed sheet refers to a design material in which, for example, a wood-grain or marble-like pattern or design is printed on a resin sheet, as shown in Fig. 16(A). In addition to the above, patterns include patterns that imitate carbon materials, and patterns that imitate the appearance of leather or cloth. By attaching the decorative printed sheet to a substrate such as resin, glass, or metal, the design of home appliances, vehicle interior parts, etc. can be enhanced. The decorative printed sheet 115 may also be called a decorative printed film.

[0244] 16(B) is a diagram showing an example of the configuration of the decorative printed sheet 115. The decorative printed sheet 115 has a printed layer 1151 on which a design (pattern) is printed by a printing method such as gravure printing or screen printing on a transparent resin layer 1150 (light-emitting side) made of a PE (polyethylene) film, a PP (polypropylene) film, a PC (polycarbonate) film, or the like, and a clear layer 1158 on the light-emitting side of the printed layer 1151 to protect the printed layer 1151. In addition, an adhesive layer 1159 made of an adhesive is arranged under the transparent resin layer 1150 (light-incident side).

[0245] Here, the thickness of the decorative printed sheet 115 is generally about 0.2 to 0.5 mm. The transparent resin layer 1150 constituting the decorative printed sheet 115 is about 0.1 mm thick, and the light transmittance of this transparent resin layer 1150 is 80 to 90% or more. On the other hand, the light transmittance of decorative printed sheets typically used as decorative films for vehicle interior materials and the design of the surfaces of home appliances varies depending on the color and darkness of the printed pattern, but in the case of dark brown woodgrain patterns or black patterns such as carbon material patterns, the light transmittance is very low, at about 1 to 5%.

[0246] Therefore, for example, as shown in Figure 16 (B), if the brightness of the image light incident from below or diagonally below the decorative printed sheet 115 is 400 to 500 nits, which is the same as that of a typical LCD display or organic EL, the brightness of the image light that passes through the upper side (light exit side) of the decorative printed sheet 115 is significantly reduced to at most about 25 nits.

[0247] 15 , when the decorative printed sheet 115 is placed above the polarization separation member 101 and the transparent member 100, the image light reflected by the retroreflective member 2 and further polarization-converted by the λ / 4 plate 21 passes through the decorative printed sheet 115 according to the above light transmittance, generating a real image, the floating-in-the-air image 3. As a result, when a user observes the floating-in-the-air image 3 from the direction of arrow A, the effect is that the floating-in-the-air image 3 appears to be floating in empty space with the pattern of the decorative printed sheet 115 as a background. In other words, using the decorative printed sheet makes it difficult for the user to recognize the existence of an optical system provided behind the floating-in-the-air image as seen by the user.

[0248] However, in the configuration of Figure 15, that is, when the image light reflected by the retroreflective member 2 is further transmitted through the decorative printing sheet 115 to generate the floating image 3, the following problems (1) and (2) arise.

[0249] Problem (1): As already mentioned, the light transmittance of the decorative printed sheet 115 is very low, about 1 to 5%, and the brightness of the floating image 3 generated after passing through the decorative printed sheet 115 is significantly reduced. In order to maintain a practical brightness (e.g., about 500 nits) for a floating image, the image light emitted from the display device 1 needs to have a brightness about 5 to 6 times higher than the brightness (e.g., 500 nits). This is problem (1).

[0250] Problem (2): To solve the problem (1), it is conceivable to use, instead of the display device 1, various self-luminous displays, specifically, displays (also referred to as image display devices, hereinafter the same) that are brighter than liquid crystal displays, such as light-emitting diode (LED) displays, organic light-emitting diode (OLED) displays (which have seen remarkable improvements in brightness in recent years), and micro-LED displays (which are rapidly becoming more practical). However, the image light (also referred to as image light, hereinafter the same) emitted from the light-emitting diode (LED) displays, organic light-emitting diode (OLED) displays, and micro-LED displays is randomly polarized and has a wide viewing angle of approximately 180°. Therefore, when a display device is used in which the image light is randomly polarized and has a wide viewing angle, at least a portion of the image light emitted from the display device passes through the polarization separation member 101. As a result, at least a portion of the image light passes through the polarization separation member 101 and reaches the user's eyes directly. As a result, when a user observes the floating image 3 (or floating image 3, hereinafter the same), the image displayed on the display device 1 below the floating image 3, with the polarization separation member 101 as the plane of symmetry, is visible along with the floating image 3, making it easier for the user to recognize the existence of the optical system located on the far side of the floating image as seen from the user. This causes a problem in that the visibility of the floating image 3 is significantly reduced, and as a result, the quality of the floating image 3 as an image is also significantly reduced. This is problem (2).

[0251] The above problems (1) and (2) are major obstacles to achieving the intended purpose of the floating-in-the-air image display device 1000 of the present invention, which is that "the provision of the decorative printed sheet 115 makes it difficult for the user to recognize the existence of the optical system provided on the far side of the floating-in-the-air image as seen from the user's perspective, and the floating-in-the-air image 3 appears to be floating in empty space with the pattern of the decorative printed sheet 115 as the background." Below, we will explain the specific configuration of this embodiment for solving the above problems (1) and (2).

[0252] First, a solution to the problem (1) will be described. Figures 17A to 17D are diagrams showing the internal structure of a decorative print sheet 115 used in the airborne image display device according to the present invention.

[0253] 17A , the decorative printed sheet 115 according to this embodiment has a configuration in which a transparent resin layer 1150 is sandwiched from above and below, with a printed layer 1151 and a printed layer 1152 formed on the upper side (light exit side) and the lower side (light entrance side), respectively. The transparent resin layer 1150 may be made of a transparent film such as a PE (polyethylene) film, a PP (polypropylene) film, or a PC (polycarbonate) film, or may be made of a glass material or a solid resin.

[0254] Here, in the upper (light-emitting side) printing layer 1151, portions 11511 where ink for printing a pattern is present and portions 11512 where no ink is present are arranged at equal intervals in the Y-axis direction, and the portions 11511 where ink is present and the portions 11512 where no ink is present have the same length ratio in the Y-axis direction, i.e., 50% of each other. Note that the portions 11512 where no ink is present may be formed by micropores. These micropores may be through-holes that penetrate the entire transparent member 100 on which the decorative printed sheet 115 is laminated.

[0255] Similarly, in the lower (light incident side) printing layer 1152, portions 11521 where ink for printing a pattern is present and portions 11522 where no ink is present are arranged at equal intervals, and the portions 11521 where ink is present and the portions 11522 where no ink is present have the same length ratio in the Y-axis direction, i.e., 50% of each other, as shown in Fig. 17A. The portions 11522 where ink is absent may be formed by micropores.

[0256] In addition, the portion 11511 where ink is present and the portion 11512 where ink is not present in the upper (light-emitting side) printing layer 1151, as well as the portion 11521 where ink is present and the portion 11522 where ink is not present in the lower (light-incident side) printing layer 1152, each have a length in the Y-axis direction of 100 μm to 300 μm, as an example.

[0257] Furthermore, although not shown in the figures, the length in the X-axis direction may be any ratio between the portion 11511 where ink is present and the portion 11512 where no ink is present in the upper (light-emitting side) printing layer 1151, and between the portion 11521 where ink is present and the portion 11522 where no ink is present in the lower (light-incident side) printing layer 1152. As with the Y-axis direction, the ratio may be 1:1, i.e., 50% of each other, or may be, for example, a ratio of 1:2 or 2:1. Furthermore, a ratio of 1:0 may be used, i.e., in the X-axis direction, the portion where ink is present extends, while the portion where ink is not present also extends in the X-axis direction.

[0258] 17A, the image portions printed on the printing layers 1151 and 1152, i.e., the portions 11511 and 11521 where printing ink is present, are offset from each other in the vertical direction (Z-axis direction), as shown in the figure. As a result, when a user views the decorative printed sheet 115 from directly above in the vertical direction, the image portions can be recognized as a continuous pattern. In other words, the user can visually recognize the image on the decorative printed sheet 115 as a single continuous pattern.

[0259] Meanwhile, the portions of the printed layers 1151 and 1152 that are not part of the image printed thereon, i.e., the portions 11512 and 11522 where no printing ink is present, are also offset in the vertical direction. Here, as shown in FIG. 17A , the retroreflected image light reflected by the retroreflective member 2 is incident on the decorative printed sheet 115 at an angle γ (approximately 45 degrees, preferably within the range of 45 degrees ±15 degrees) with respect to the normal to the plane of the decorative printed sheet 115. Therefore, from the user's viewpoint (the direction of arrow A in FIG. 15 ), the retroreflected image light is less likely to be blocked by the printed layers 1151 and 1152, allowing the floating image 3 to be viewed. In other words, the decorative printed sheet 115 can better prevent a reduction in the brightness of the floating image 3 viewed by the user.

[0260] 17A , the ink-containing portions 11511 and 11521 and the ink-free portions 11512 and 11522 have the same length ratio in the Y-axis direction (1:1). However, the ink-containing portions 11511 and 11521 and the ink-free portions 11512 and 11522 do not necessarily have to have the same ratio (1:1). The ink-containing portions 11511 and 11521 and the ink-free portions 11512 and 11522 may be shifted from each other in the Z-axis direction at a ratio of 1:2, 2:1, 1:3, 3:1, 1:4, 4:1, or the like so that the ink-containing portions 11511 and 11521 and the ink-free portions 11512 and 11522 are not blocked by the printed layers 1151 and 1152 when the retroreflected image light is incident on the decorative printed sheet 115.

[0261] Next, Figure 17B is a diagram showing another example of the configuration of the decorative printed sheet 115 in this embodiment. In Figure 17B, the pattern portion of the printing layer 1151, i.e., the portion 11513 where printing ink is present, and the portion of the printing layer 1151 that is not a pattern portion, i.e., the portion 11512 where printing ink is not present, are arranged alternately in the left-right direction of the figure. The area of ​​the portion 11513 where printing ink is present is large, and the area of ​​the portion 11512 where printing ink is not present is small. Note that the portion 11512 where printing ink is not present may be formed by micropores.

[0262] 17B , when comparing lengths in the Y-axis direction (left-right direction) of the figure, the ratio of the portion 11513 where printing ink is present to the portion 11512 where printing ink is not present is, for example, 4 to 1. Therefore, when a user views the decorative printed sheet 115 from directly above in the vertical direction, the portion 11513 where printing ink is present, i.e., the pattern portion, accounts for the majority of the area. As a result, the user can recognize the pattern created by the decorative printed sheet 115 as a nearly continuous pattern.

[0263] 17B , the lower portion 1153 of the decorative printed sheet 115 is made up of a portion 11531 printed with black or dark ink (e.g., dark gray or dark brown) and a portion 11532 with nothing printed thereon, and the ratio between the two, i.e., the portion 11531 printed with black or dark ink and the portion 11532 with nothing printed thereon, is, for example, 4 to 1. The portion 11532 with no printing ink may be formed by micropores.

[0264] Furthermore, as described above, the lower portion 1153 of the decorative printed sheet 115 has a high proportion of portions 11531 printed with black or dark ink. Therefore, when a user looks down on the decorative printed sheet 115 from directly above in the vertical direction, the vertically lower side of the portion 11512 in the upper portion 1151 of the decorative printed sheet 115 where there is no printing ink is black or dark, and therefore the portion 11512 where there is no printing ink cannot be recognized as transparent resin, and the user can recognize the pattern as a continuous pattern.

[0265] Furthermore, as shown in Figure 17B, in the printing layer 1151, the portion 11512 where there is no printing ink, i.e., the portion with a light transmittance of 80 to 90%, and in the lower portion 1153 of the decorative printing sheet 115, the portion 11532 where nothing is printed, i.e., the portion with a light transmittance of 80 to 90%, are arranged so as to form an angle γ with respect to the normal to the plane of the decorative printing sheet 115 (for example, approximately 45 degrees; a range of 45 degrees ± 15 degrees is preferable).

[0266] Therefore, from the user's viewpoint (the direction of arrow A in FIG. 15 ), the retro-reflected image light is less likely to be blocked by the printed layers 1151 and 1153, and the user can see the floating-in-the-air image 3. In other words, it is possible to further prevent the decorative printed sheet 115 from reducing the brightness of the floating-in-the-air image 3 as seen by the user.

[0267] 17A and 17B, the retroreflected image light reflected by the retroreflective member 2 is less likely to be blocked by the printed layers 1151, 1152, and 1153, making it possible to view the floating image 3. In other words, it is possible to further prevent the decorative printed sheet 115 from reducing the brightness of the floating image 3 viewed by the user. Therefore, by configuring the decorative printed sheet 115 as shown in FIGS. 17A and 17B, it is possible to solve the above-mentioned problem (1), i.e., the problem that the brightness of the floating image 3 generated after passing through the decorative printed sheet 115 is significantly reduced.

[0268] Next, a configuration that solves the above-mentioned problem (1) will be described with reference to Figures 17C and 17D. The decorative printed sheet 115 shown in Figures 17A and 17B has a configuration including printed layers 1151, 1152, and 1153 on both the upper side (light-emitting side) and the lower side (light-incident side) of a transparent resin layer 1150. On the other hand, the decorative printed sheet 115 shown in Figures 17C and 17D differs in configuration from the decorative printed sheet of Figures 17A and 17B in that it has a printed image 1151 only on the upper side (light-emitting side) of the transparent resin layer 1150.

[0269] First, the structure of the decorative printed sheet 115 shown in Fig. 17C will be described. As shown in Fig. 17C, a printed layer 1151 is provided only on the upper side of a transparent resin layer 1150. Here, the printed layer 1151 is characterized in that portions 11511 where ink for printing a pattern is present and portions 11512 where no ink is present are arranged at equal intervals in the Y-axis direction, and the portions 11511 where ink is present and the portions 11512 where no ink is present are at the same ratio, i.e., 50% each. Note that the portions 11512 where no ink is present may be formed by micropores.

[0270] In the configuration of Figure 17C above, the decorative printed sheet 115 has the characteristic of not only transmitting the retroreflected image light (forming an angle γ with the normal to the XY plane) from the retroreflective member 2 shown in Figure 15, but also transmitting the image light (forming an angle -γ with the normal to the XY plane) from the display device 1.

[0271] 17A and 17B, the decorative printed sheet 115 could only be placed on the upper side (light-exit side) of the polarization separation member 101 and the transparent member 100 in FIG. 15. However, in the case of the decorative printed sheet 115 shown in FIG. 17C, although not shown, it is possible to place the decorative printed sheet 115 not only on the upper side (light-exit side) of the polarization separation member 101 in FIG. 15 but also on the lower side (light-incident side) of the polarization separation member 101 after attaching the decorative printed sheet 115 to the transparent member 100. Here, the polarization separation member 101 is very thin, with a thickness of 0.1 to 0.3 mm, and therefore difficult to place alone, and therefore may be used by attaching it to the transparent member 100 (specifically, a glass plate).

[0272] Next, the configuration of the decorative printed sheet 115 shown in Fig. 17D will be described. As shown in Fig. 17D, the decorative printed sheet 115 is the same as Fig. 17C in that a printed layer 1151 is provided only on the upper side (light-emitting side) of the transparent resin layer 1150. However, the decorative printed sheet 115 of Fig. 17D differs in configuration from Fig. 17C in that the printed layer 1151 is composed only of a portion 11511 where ink for printing a pattern is present.

[0273] 17D includes a transparent resin layer 1150, a printing layer 1151, and a clear layer 1158 disposed above the printing layer 1151 (on the light-emitting side) to protect the printing layer 1151. An adhesive layer 1159 made of adhesive is disposed below the transparent resin layer 1150 (on the light-incident side). The decorative printed sheet 115 shown in FIG. 17D differs in configuration from the decorative printed sheet shown in FIG. 17C in that it includes holes 11530 that penetrate each of these layers at a predetermined angle.

[0274] Here, after the decorative printed sheet 115 is constructed, the through holes 11530 can be realized as through holes with any diameter and any angle by laser processing or the like. Specifically, the diameter of the through holes is preferably 0.1 to 0.3 mm, and the angle of the through holes is preferably approximately 45°. An angle of 45°±15° is also suitable. As a result, as shown in FIG. 17D , the decorative printed sheet 115 makes it difficult for the retroreflected image light from the retroreflective member 2 to be blocked, and a reduction in the brightness of the floating image 3 as viewed by the user can be further prevented.

[0275] As described above, the decorative printed sheet 115 shown in Figures 17C and 17D can further prevent a decrease in the brightness of the floating image 3 visually recognized by the user. Therefore, by configuring the decorative printed sheet 115 as shown in Figures 17C and 17D, it is possible to solve the above problem (1), i.e., the problem that the brightness of the floating image 3 generated after passing through the decorative printed sheet 115 is significantly reduced.

[0276] Next, a solution to the problem (2) of this embodiment will be described. As already explained with reference to Figures 5 to 12, by using light source device 13, which has a narrow divergence angle and is capable of emitting light with higher brightness than conventional light sources, as the light source (backlight) of liquid crystal display panel 11, it is possible to obtain a spatially floating image 3 with higher brightness, less ghosting, and better visibility than conventional liquid crystal display devices.

[0277] However, when using a display device such as a light-emitting diode (LED) display, recent organic EL display, or micro LED display, which has higher brightness than an LCD display but which generates randomly polarized image light and has a wide divergence angle of approximately 180°, at least a portion of the image light emitted from the display device passes through the polarization separation member 101. As a result, when a user observes the levitating image 3, an image displayed on the display device below the levitating image 3, with the polarization separation member 101 as the plane of symmetry, is viewed together with the levitating image 3, resulting in a problem in which the visibility of the levitating image 3 is significantly reduced.

[0278] This is the problem (2) already mentioned, and it is necessary to solve it in order to realize a suitable floating image display device. To solve the above problem, we have devised two main solutions (first solution and second solution) as described below. We will explain them in order.

[0279] First, the first solution will be described below. Fig. 18(A) is an enlarged view of the display device 1 of the floating image display device 1000 (Example 3) shown in Fig. 15. In Fig. 18(A), the display device 1 comprises a light source device (backlight) 13, a liquid crystal display panel 11, and an absorptive polarizer 12. The functions and features of these components of the display device 1 have already been described, but the greatest feature of the display device 1 used in this example is that the divergence angle of the light source light emitted from the light source device 13 is extremely narrow compared to the light source devices (backlights) of commonly available liquid crystal display devices.

[0280] The viewing angle characteristics of the display device 1 using the light source device 13 have already been described with reference to Fig. 12 and other figures. Specifically, as shown in Fig. 12, by using the light source device 13, the diffusion characteristics of the light flux emitted from the liquid crystal display panel 11 are characterized in that the viewing angle (half brightness viewing angle) at which the luminance is 50% of that in a front view (angle of 0 degrees) is very narrow, at about 13 degrees. As a result, by using the display device 1 of this embodiment, it is possible to configure a display device having a very narrow divergence angle compared to general liquid crystal televisions, liquid crystal displays, and the like.

[0281] 15 again, the image light emitted from display device 1 travels toward polarization separation member 101 at a narrow diffusion angle, as described above. The image light emitted from liquid crystal display panel 11 is linearly polarized light, specifically, S-polarized light or P-polarized light. Here, for example, if the image light emitted from display device 1 is S-polarized light, polarization separation member 101 that reflects S-polarized light and, conversely, transmits P-polarized light is used.

[0282] As a result, the S-polarized image light emitted from the display device 1 is reflected by the polarization separation member 101 and directed toward the retroreflective member 2. The image light retroreflected by the retroreflective member 2 passes through the λ / 4 plate 21 provided on the light incident and exit surface (retroreflective surface) of the retroreflective member 2 twice, once upon incidence and once upon exit, and is converted into P-polarized image light. As a result, the P-polarized image light passes through the polarization separation member 101, the transparent member 100, and further the decorative printed sheet 115 according to this embodiment, and forms and displays a real image, a floating image 3, on the image display surface of the display device 1, i.e., at a position plane-symmetrical to the liquid crystal display panel 11, with the polarization separation member 101 as the plane of symmetry.

[0283] 18(A) uses a display device with a narrow divergence angle, a polarization separation member 101 prevents transmission of polarized light other than a predetermined polarization, and / or uses an absorbing polarizer 12. This makes it possible to further prevent the image displayed on the display device 1 from being viewed together with the floating image 3, and to prevent the user from being aware of the existence of an optical system provided on the far side of the floating image 3 as seen from the user.

[0284] Next, a case where a display device 1811 is used instead of the display device 1, as shown in FIG. 18B, will be described. The display element 1801 of the display device 1811 is a display element that displays a randomly polarized video or image. Specific examples of the display element 1801 include a self-luminous display such as a light-emitting diode (LED) display element, an organic EL display, or a micro-LED display, which is a display element in which very small LED chips with a diameter of a few micrometers are laid out on a surface. These display elements have significantly higher brightness (e.g., 2000 to 5000 nits) than liquid crystal displays, and can realize a display device with a wide viewing angle of nearly 180 degrees, i.e., brightness remains constant regardless of the user's position and from which direction the display is viewed. The display element 1801 of the display device 1811 may also be a digital mirror device (DMD) that modulates light from a backlight.

[0285] On the other hand, when display device 1811 using the above-described display element 1801 is used as a display device for a floating-in-the-air video display device (which may be referred to as a floating-in-the-air image display device; the same applies hereinafter when display element 1801 and display device 1811 are used), a floating-in-the-air video 3 (which may be referred to as a floating-in-the-air image 3; the same applies hereinafter when display element 1801 and display device 1811 are used) with correspondingly higher brightness can be generated due to the high brightness of display device 1811. However, display device 1811 has a characteristic of having a wide viewing angle, and further, the light (video light) emitted from display device 1811 is not originally polarized light like the video light from a liquid crystal display panel, i.e., it is randomly polarized video light.

[0286] As already mentioned, when the display device 1811 is used as a floating-in-the-air image display device equipped with the decorative printed sheet 115, when the user observes the floating-in-the-air image 3, the image light has a wide viewing angle and is not polarized light (it is randomly polarized image light), so as previously mentioned as problem (2), at least a portion of the image light emitted from the display device passes through the polarization separation member 101 and reaches the user's eyes directly. As a result, when the user observes the floating-in-the-air image 3, the problem arises that the image displayed on the display device 1 below the floating-in-the-air image 3, with the polarization separation member 101 as the plane of symmetry, is viewed together with the floating-in-the-air image 3.

[0287] To solve the above problem, as shown in Fig. 18B, a polarizing plate 221 is provided on the image light emitting surface of the display element 1801. A polarizing plate (also called a polarizer, polarizing optical element, polarizing optical member, etc.) is an element that converts randomly polarized light into light of a specific polarization. The randomly polarized image light emitted from the display element 1801 passes through the polarizing plate 221 and is converted into, for example, S-polarized image light, which is linearly polarized light.

[0288] The image light converted into S-polarized image light is the same linearly polarized image light as the image light emitted from the liquid crystal display panel 11, so it does not pass directly through the polarization separation member 101 and does not directly enter the user's eyes after passing through the polarization separation member 101. This solves the problem of an image displayed on a display device being viewed below the floating image 3 together with the floating image 3. The first solution has been described above.

[0289] On the other hand, the image light converted to S-polarized light by the polarizing plate 221 still has a wide viewing angle of approximately 180 degrees. As a result, not only does the image light converted to S-polarized light exit in the direction of the polarization separation member 101, but at least a portion of the image light heads directly toward the retroreflective member 2. As described in FIG. 3, at least a portion of the image light behaves as if it were incident at an angle, causing ghost images. This not only impairs the image quality of the floating-in-the-air image, but the ghost images caused by the above factors also significantly impede the intended purpose of this embodiment, which is to "make it difficult for the user to recognize the presence of an optical system installed behind the floating-in-the-air image from the user's perspective by providing the decorative printed sheet 115, and make the floating-in-the-air image 3 appear to be floating in empty space against the background of the pattern on the decorative printed sheet 115."

[0290] 18C, an image light control sheet 334 is disposed on the image light output surface side of the display element 1801. As its name suggests, the viewing angle control film is a film-like member that controls the viewing angle of the image light so as to limit it to a narrow range of 20° to 30°.

[0291] 18C , the image light control sheet 334 is disposed on the image display surface of the display element 1801, and furthermore, the polarizing plate 221 is disposed on the image light exit surface of the image light control sheet 334. Here, the top-bottom relationship between the image light control sheet 334 and the polarizing plate 221 does not matter. That is, a configuration may be adopted in which the polarizing plate 221 is disposed on the image display surface of the display element 1801, and furthermore, the image light control sheet 334 is disposed on the image light exit surface of the polarizing plate 221.

[0292] Fig. 19 shows an example of the structure of the image light control sheet 334. As shown in Fig. 19, the image light control sheet 334 has a sandwich structure in which transparent silicone 336 and black silicone 337 are alternately arranged, with synthetic resin arranged on the light incident and exit surfaces. Here, the viewing angle characteristics of the image light control sheet 334 are determined by the thickness d1 of the black silicone 337 and the spacing d2 between the black silicone. The image light control sheet 334 can achieve a viewing angle of 20° to 30°, i.e., a narrow viewing angle of approximately ±10° to ±15°, for the image light.

[0293] 18C , the image light control sheet 334 can narrow the viewing angle of the image light emitted from the display element 1801, and furthermore, the polarizing plate 221 can convert randomly polarized image light into image light with a specific polarization. As a result, even when using a display device such as a micro LED display that has high brightness, a wide viewing angle of image light, and randomly polarized image light, the above-mentioned problem (2) can be solved.

[0294] As described above, it is possible to provide a more suitable floating image display device that achieves the intended purpose of the present invention, which is to "make it difficult for the user to recognize the existence of the optical system located at the back of the floating image from the user's perspective, and make the floating image 3 appear to be floating in empty space with the pattern created by the decorative printing sheet 115 as the background."

[0295] <Another Configuration Example 5 of the Optical System of the Space-Floating Image Display Device> Next, a configuration example using another optical system different from that shown in FIG. 15 in the space-floating image display device 1000 using the decorative printed sheet according to Example 3 of the present invention will be described. Specifically, the space-floating image display device 1000 of this configuration example has a configuration using the retroreflector 5 (imaging optical plate) shown in FIGS. 2D and 4O. Also, as already described in FIG. 2D , the retroreflector 5 is configured with a corner reflector array. As shown in FIG. 20 , a chief ray 9020 representing the light beam (image light) emitted from the display device 10 travels toward the retroreflector 5 and is incident on the retroreflector 5 at an incident angle of (90°-γ). Here, the angle γ is, for example, approximately 45°, and further, the incident angle (90°-γ) may be in the range of 45°±15°. More specifically, the incident angle of the image light on the retroreflector 5 may be 30° to 60°.

[0296] Fig. 20 shows the main components of a floating image display device 1000 according to this configuration example. As shown in Fig. 20, the display device 10 is configured with a liquid crystal display panel 11 and a light source device 13 that supplies light to the liquid crystal display panel 11 and generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 may be configured with a screen size ranging from a small one with a screen size of about 5 inches to a large one exceeding 80 inches.

[0297] The image light from the liquid crystal display panel 11 is incident at an oblique angle on the retroreflector 5 placed directly opposite the panel 11. As described above, the image light is incident on the retroreflector 5 at an incident angle of 45°, for example. The retroreflector 5 may also be referred to as a retroreflective member 5.

[0298] 20, the solid arrow 9020 indicates the chief ray image light representing the light beam incident on the retroreflector 5 from the liquid crystal display panel 11, and the dotted arrows (multiple arrows) indicate the light beams emitted from the retroreflector 5, forming and displaying the real image, the floating-in-the-air image 3. The user can observe the floating-in-the-air image 3 from direction A.

[0299] The floating-in-the-air image display device 1000 shown in Fig. 20 is equivalent to the floating-in-the-air image display device shown in Fig. 2D in the above configuration. However, the floating-in-the-air image display device 1000 shown in Fig. 20 differs from the floating-in-the-air image display device shown in Fig. 2D in that a decorative printed sheet 115 is placed or adhered to the upper part of the transparent member 100.

[0300] Here, the decorative printed sheet 115 arranged or adhered to the upper part (light exit side) or lower part (light entrance side) of the transparent member 100 shown in Fig. 20 has the same material and structure as those shown in Fig. 17A to Fig. 17D. Therefore, in this embodiment as well, by arranging the decorative printed sheet 115, it is possible to make it difficult for the retroreflected image light reflected by the retroreflective member 5 to be blocked, and the user can more easily view the floating image 3.

[0301] In Figure 20, a transparent member 100 is placed on the light exit surface of the retroreflective member 5, and a decorative printed sheet 115 is further placed or adhered to the light exit surface of the transparent member 100, but the transparent member 100 is not necessarily required, and the decorative printed sheet 115 may be placed or adhered directly to the light exit surface of the retroreflective member 5.

[0302] Furthermore, in Figure 20, a configuration is shown in which the display device is a display device 10 composed of a liquid crystal display panel 11 and a light source device 13, but the display device is not limited to the display device 10, and a display element 1801 shown in Figures 18(B) and 18(C) may also be used.

[0303] 21A and 21B are diagrams showing the main components of a modified example of this configuration example of a floating image display device when a display element 1801 is used as the display device. Specifically, the display element may be, for example, a light-emitting diode (LED) display element, an organic light-emitting diode (OLED) display, or a micro-LED display, which is a display element in which very small LED chips with a diameter of a few μm are spread over a surface.

[0304] Furthermore, the retroreflector 5 shown in FIG. 21A is configured, for example, by a corner reflector array, as described in FIGS. 2E to 2I. Therefore, the image light 9020 does not need to be image light with a specific polarization, and may be image light with random polarization. Therefore, the display element 1801 can be used as is as a display device. In other words, the display element 1801 does not need to be provided with a polarizing plate, as in the display device 1811 of FIG. 18B.

[0305] 21A, when the display element 1801 is used as is, the image light emitted from the display element 1801 travels toward the retroreflector 5 and is incident on the retroreflector 5 at an incident angle of (90°-γ). Here, the angle γ is, for example, approximately 45°, and may also be in the range of 45°±15°.

[0306] In this case, as shown in Fig. 21B, an image light control sheet 334 may be disposed on the image display surface of the display element 1801 in order to restrict the incident angle γ to a specific range, such as 45°±15°. By disposing the image light control sheet 334, the viewing angle of the image light can be narrowed to a range of 20° to 30°, in other words, ±10° to ±15°, relative to the center of the image light. In the example of Fig. 21B, the display element 1801 does not need to include a polarizing plate as in the display device 1811 of Fig. 18B.

[0307] In Figures 21 (A) and (B), a transparent member 100 is placed on the light exit surface of the retroreflective member 5, and a decorative printed sheet 115 is further placed or adhered to the light exit surface of the transparent member 100. However, the transparent member 100 is not necessarily required, and the decorative printed sheet 115 may be placed or adhered directly on the retroreflective member 5.

[0308] As described above, by providing the image light control sheet 334 on the image display surface of the display element 1801, when a user observes the floating image 3 from direction A, it is possible to reduce the possibility that the image light emitted from the display element 1801 will be directly visible below the decorative printing sheet 115, resulting in improved visibility of the floating image 3.

[0309] In other words, even in the configuration examples shown in Figures 20 and 21, it is possible to provide a more suitable floating image display device that achieves the intended purpose of the present invention, which is to "make it difficult for the user to recognize the existence of the optical system located at the back of the floating image as seen from the user's perspective, and make the floating image 3 appear to be floating in empty space with the pattern created by the decorative printing sheet 115 as the background."

[0310] 22 and 23 , the specific shapes of the portions 11511, 11513, 11521, and 11531 where ink is present for printing a pattern on the decorative printed sheet 115 according to Example 3 and the portions 11512, 11522, and 11532 where no ink is present will be described. Figures 22(1) and 23(1) are views of the decorative printed sheet 115 viewed from the normal direction (z direction) of the plane of the decorative printed sheet 115, with the black portions being the portions 11511, 11513, 11521, and 11531 where ink is present and the white portions being the portions 11512, 11522, and 11532 where no ink is present. The portions 11512, 11522, and 11532 where no ink is present are portions that mainly transmit light and may therefore be referred to as openings. The example of Figure 22 is an example in which the ink-free portions 11512, 11522, and 11532 (openings 2201) are formed in a rectangular shape, such as a rectangle. The example of Figure 23 is an example in which the ink-free portions 11512, 11522, and 11532 (openings 2301) are formed in a round shape, such as an oval. The examples of Figures 22 and 23 show examples in which openings of the same shape are periodically arranged. By periodically arranging openings of the same shape in this way, the decorative printed sheet 115 can be manufactured inexpensively. If necessary for other reasons, the shapes of these openings in the decorative printed sheet 115 do not necessarily have to be completely identical, and the arrangement does not necessarily have to be completely periodic.

[0311] Fig. 22(2) is an enlarged view of one of the openings 2201 shown in Fig. 22(1). The length of opening 2201 in the x direction (left-right direction as seen from the user viewing the floating-in-the-air image) is indicated as x1, and the length of opening 2201 in the y direction perpendicular to the x direction (front-back direction as seen from the user viewing the floating-in-the-air image) is indicated as y1. Fig. 23(2) is an enlarged view of one of the openings 2301 shown in Fig. 23(1). The length of opening 2301 in the x direction (left-right direction as seen from the user viewing the floating-in-the-air image) is indicated as x2, and the length of opening 2301 in the y direction perpendicular to the x direction (front-back direction as seen from the user viewing the floating-in-the-air image) is indicated as y2.

[0312] The examples of Figures 22 and 23 may be applied to any of the decorative printed sheets 115 described in Figures 15 to 21. Here, when the light beam forming the floating-in-the-air image passes through the opening of the decorative printed sheet 115 at an angle γ with respect to the normal to the plane of the decorative printed sheet 115, the effective opening shape of the light beam forming the floating-in-the-air image is the shape of the opening of the decorative printed sheet 115 projected onto a plane perpendicular to the traveling direction of the light beam forming the floating-in-the-air image. Therefore, to ensure a more symmetrical shape of the effective opening shape of the light beam forming the floating-in-the-air image, it is desirable to make the length in the y direction longer than the length in the x direction in the opening shape on the plane of the decorative printed sheet 115 in the examples of Figures 22 and 23. Otherwise, the effective opening would be shorter in the direction corresponding to the y direction of the decorative printed sheet 115 in the plane perpendicular to the traveling direction of the light beam forming the floating-in-the-air image. Therefore, when the example of FIG. 22(2) is used with the decorative printed sheet 115 described in FIGS. 15 to 21, if the light beam forming the floating-in-the-air image is incident at an angle γ relative to the perpendicular to the plane of the decorative printed sheet 115, it is desirable to satisfy y1 > x1. Furthermore, when the example of FIG. 23(2) is used with the decorative printed sheet 115 described in FIGS. 15 to 21, if the light beam forming the floating-in-the-air image is incident at an angle γ relative to the perpendicular to the plane of the decorative printed sheet 115, it is desirable to satisfy y2 > x2. By using such a shape, the effective opening shape of the light beam forming the floating-in-the-air image can be made more symmetrical, thereby maintaining the uniformity of the image quality of the floating-in-the-air image. Note that, if necessary for other reasons, the relationship between the x-direction length and the y-direction length of the shapes of these openings in the decorative printed sheet 115 does not necessarily have to satisfy the relationship in the above formula.

[0313] The opening shapes shown in the examples of Fig. 22 and Fig. 23 may be generated by various mask processes during or after printing. These opening shapes may be provided by microholes or the like. These opening shapes may also be generated by laser processing or the like as described in Fig. 17D.

[0314] The decorative printed sheet with the aperture shapes shown in Figures 22 and 23 described above can display floating images with better image quality. Furthermore, the decorative printed sheet with the aperture shapes shown in Figures 22 and 23 can be manufactured more inexpensively.

[0315] According to the above-described floating-in-the-air video display device / floating-in-the-air image display device according to the third embodiment of the present invention, a more suitable display technique using a decorative print sheet can be provided.

[0316] The technology according to this embodiment displays high-resolution, high-brightness video information 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 United Nations' Sustainable Development Goals (SDGs), which aim to "ensure good health and well-being for all."

[0317] Furthermore, the technology according to 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, resulting in high light utilization efficiency and enabling the production of bright and clear floating images. The technology according to 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 towns sustainable."

[0318] 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 in order 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.

[0319] 1, 10...display device, 2...retroreflector (retroreflector), 3...aerial image (floating image), 5...retroreflector, 12...absorptive polarizer, 13...light source device, 54...light direction conversion panel, 100...transparent member, 101...polarization separation member, 101B...polarization separation member, 105...window glass, 102, 202...LED substrate, 115...decorative printed sheet, 221...polarizer, 203...light guide, 205, 271...reflective sheet, 206, 270...phase difference plate, 230...user, 334...image light control sheet, 1000...floating image display device, 1110...control unit, 1160...image control unit, 1180...imaging unit, 1102...image display unit, 1350...air operation detection unit, 1351...air operation detection sensor, 1811...display device.

Claims

1. An air-floating image display device comprising: an image source; and an optical system that generates air-floating image generating light for forming an air-floating image based on the image light generated by the image source, wherein the optical system has a transparent member on which a decorative printed layer is laminated, and the air-floating image is generated by light that has passed through the transparent member on which the decorative printed layer is laminated.

2. An air-floating image display device according to claim 1, wherein the decorative print layer has areas where printing ink is present and areas where printing ink is not present alternately at a predetermined pitch.

3. A floating-in-the-air image display device as described in claim 1, wherein the transparent member on which the decorative printed layer is laminated has a printed layer printed with printing ink on both the incident surface and the exit surface of the transparent member for generating the floating-in-the-air image, in order to generate the floating-in-the-air image.

4. A floating-in-the-air image display device as described in claim 3, wherein the positions of the portions of the printing layer on the incident surface side of the transparent member where the floating-in-the-air image generating light is incident and the portions of the printing layer on the exit surface side of the transparent member where the printing ink is present and the portions of the printing layer on the exit surface side of the transparent member where the floating-in-the-air image generating light is exited are different from the positions of the portions of the printing layer on the transparent member where the printing ink is present and the portions of the printing ink is not present in the direction parallel to the plane of the transparent member.

5. A floating-in-the-air image display device as described in claim 3, wherein the positions of the transparent member at the portions of the printing layer on the emission surface side of the light generating the floating-in-the-air, where printing ink is present, and the positions of the transparent member at the portions of the printing layer on the incidence ... are offset at an angle tilted by a predetermined angle from the normal direction of the plane of the transparent member.

6. A floating-in-the-air image display device according to claim 5, wherein the predetermined angle is approximately 45 degrees.

7. A floating-in-the-air image display device according to claim 5, wherein the predetermined angle is in the range of 45 degrees ±15 degrees.

8. A floating-in-the-air image display device as described in claim 5, wherein the predetermined angle is within the range of ±15 degrees with respect to the traveling direction of the floating-in-the-air image generating light passing through the transparent member on which the decorative print layer is laminated.

9. A floating-in-the-air image display device as described in claim 1, wherein the image source is an image source that generates image light mainly composed of a predetermined polarization, and the optical system has a polarization separation member that transmits image light of one polarization and reflects image light of the other polarization, a retroreflective member that retroreflects the image light from the polarization separation member, and a phase difference plate provided on the retroreflective surface of the retroreflective member, and the image light that has been transmitted or reflected by the polarization separation member, the retroreflective member and the phase difference plate passes through the decorative printing layer.

10. An air-floating image display device as claimed in claim 1, wherein the optical system has an imaging optical plate for forming the air-floating image, and image light that has been reflected multiple times at the imaging optical plate passes through the decorative printing layer.

11. The air-floating image display device according to claim 1, wherein the image source is a display device having a liquid crystal display panel.

12. A floating-in-the-air image display device according to claim 1, wherein the image source is a randomly polarized image source that emits image light with random polarization.

13. A floating-in-the-air image display device according to claim 12, wherein an image light control sheet for controlling the emission angle of the image light is disposed on an emission surface of the image light from the randomly polarized image source.

14. The air-suspended image display device according to claim 12, wherein the randomly polarized image source is an LED display.

15. The air-floating image display device according to claim 12, wherein the randomly polarized image source is an organic electroluminescence display.

16. An air-floating image display device as described in claim 1, wherein the decorative printing layer has a portion where printing ink is present and a portion where printing ink is not present, and the portion where printing ink is not present is formed by micropores.

17. An air-floating image display device according to claim 16, wherein the fine holes in the decorative print layer are through holes penetrating the transparent member on which the decorative print layer is laminated.

18. A floating-in-the-air image display device according to claim 16, wherein the micropores penetrate at a predetermined angle inclined with respect to the plane of the decorative print layer.

19. The air-floating image display device according to claim 18, wherein the predetermined angle is approximately 45 degrees.

20. The air-floating image display device according to claim 18, wherein the predetermined angle is in the range of 45 degrees ±15 degrees.

21. A floating-in-the-air image display device as described in claim 1, wherein the decorative printing layer has a portion where printing ink is present and a portion where printing ink is not present, the portion where printing ink is not present is an opening through which floating-in-the-air image generating light passes through a transparent member on which the decorative printing layer is laminated, and the shape of the opening is rectangular.

22. A floating-in-the-air image display device as described in claim 1, wherein the decorative printed layer has a portion where printing ink is present and a portion where printing ink is not present, the portion where printing ink is not present is an opening through which floating-in-the-air image generating light passes through a transparent member on which the decorative printed layer is laminated, and the shape of the opening is round.

23. A floating-in-the-air image display device as described in claim 1, wherein the decorative printed layer has portions where printing ink is present and portions where printing ink is not present, and the portions where printing ink is not present are openings through which floating-in-the-air image generating light passes through a transparent member on which the decorative printed layer is laminated, and when a first direction is defined as the left-right direction as seen by a user viewing the floating image in the plane of the decorative printed layer and a second direction is defined as a direction perpendicular to the first direction in the plane of the decorative printed layer, the length of the shape of the opening in the second direction is longer than the length of the shape of the opening in the first direction.

Images