Floating image display device

Abstract

To provide a more appropriate floating image display device which contributes to sustainable development goals (SDGs) of "3. good health and well-being for all," "9. building a foundation for industry and technological innovation," and "11. creating sustainable cities."SOLUTION: A floating image display device is provided, comprising a display device provided inside a housing to emit image light, an optical system for forming a floating image that floats in the air outside the housing from the image light, an air operation detection sensor for detecting an operating object of the floating image, and a duct for discharging heat generated by the display device, where the heat is discharged from the duct in a direction away from the floating image.SELECTED DRAWING: Figure 13B

Description

[Technical Field]

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

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

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

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

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

[0006] To solve the above problems, for example, the configuration described in the claims is adopted. The present application includes multiple means for solving the above problems, but one example is the following configuration: A display device provided inside a housing and emitting image light, an optical system that forms a floating image floating in the air outside the housing from the image light, an air operation detection sensor that detects a control object in the floating image, and a duct that exhausts heat generated by the display device, and the heat exhausted from the duct is exhausted avoiding the floating image. [Effects of the Invention]

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

[0008] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image display device according to an embodiment of the present invention; [Figure 2A] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2B] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2C] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 2D] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a floating-in-the-air image display device according to an embodiment of the present invention; [Figure 2E] 1 is a projection view of a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention; [Figure 2F] 1 is a top view of a retroreflector constituting a floating-in-the-air image display device according to an embodiment of the present invention; FIG. [Figure 2G] FIG. 1 is a perspective view showing a corner reflector that constitutes a retroreflector that constitutes a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 2H] FIG. 1 is a top view showing a corner reflector that constitutes a retroreflector that constitutes a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 2I] FIG. 1 is a side view showing a corner reflector that constitutes a retroreflector that constitutes a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4A] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4B] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4C] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4D] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4E] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4F] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4G] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4H] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4I] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4J] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4K] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4L] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4M] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4N] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4O] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4P] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 5] 1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 6]1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 7] 1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 8] 1 is a layout diagram showing a main part of a space floating image display device according to an embodiment of the present invention; [Figure 9] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 11] 1 is an explanatory diagram for explaining the light source diffusion characteristics of an image display device according to an embodiment of the present invention. [Figure 12] 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device according to an embodiment of the present invention; [Figure 13A] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 13B] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 14] 1 is a perspective view showing an example of a configuration of a space floating image display device according to an embodiment of the present invention; [Figure 15] 1 is a front view of a display device of a space floating image display device according to an embodiment of the present invention; [Figure 16] 1 is a diagram showing an example of the configuration of an exhaust opening of a space floating image display device according to an embodiment of the present invention; [Figure 17] 1 is a diagram showing an example of the configuration of an exhaust opening of a space floating image display device according to an embodiment of the present invention; [Figure 18] 1 is a diagram showing an example of the configuration of an exhaust opening of a space floating image display device according to an embodiment of the present invention; [Figure 19] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 20] 1 is a perspective view showing an example of a configuration of a space floating image display device according to an embodiment of the present invention; [Figure 21]1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 22] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 23] 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; DETAILED DESCRIPTION OF THE INVENTION

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

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

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

[0012] Example 1 An example of the configuration of a space floating image display device will be described below as a first embodiment of the present invention.

[0013] <Example of how to use the space floating image display device> FIG. 1 is a diagram showing an example of a usage form of a space-floating image display device according to an embodiment of the present invention, and is a diagram showing the overall configuration of the space-floating image display device according to this embodiment. The specific configuration of the space-floating image display device will be described in detail using FIG. 2 and other figures. Light with a narrow-angle directional characteristic and specific polarization is emitted from image display device 1 as an image light beam, reflected by the optical system within the space-floating image display device, and then incident on retroreflector 2. It is then retroreflected and transmitted through transparent member 100 (glass, etc.), forming a real aerial image (space-floating image 3) on the outside of the glass surface. In the following embodiments, the retroreflector 2 (retroreflector) is used as an example of a 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.

[0014] In addition, in a store or the like, a space is partitioned by a show window (also called "window glass") 105, which is a translucent member such as glass. According to the space floating image display device of this embodiment, it is possible to transmit such a transparent member and display a floating image in one direction to the outside and / or inside of the store (space).

[0015] 1, the inside of the window glass 105 (inside the store) is shown in the depth direction, and the outside (for example, the sidewalk) is shown in the foreground. On the other hand, by providing a means for reflecting specific polarized waves on the window glass 105, it is possible to reflect the waves and form an aerial image at a desired position inside the store.

[0016] <Configuration example of optical system for space floating image display device> 2A is a diagram showing an example of the configuration of an optical system of a space-floating image display device according to one embodiment of the present invention. The configuration of the space-floating image display device will be described in more detail using FIG. 2A. As shown in FIG. 2A(1), a display device 1 that diverges specific polarized image light at a narrow angle is provided in an oblique direction of a transparent member 100 such as glass. The display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates specific polarized light with narrow-angle diffusion characteristics.

[0017] Image light of a specific polarization from the display device 1 is reflected by a polarization separator 101 (in the figure, the polarization separator 101 is formed into a sheet and adhered to the transparent member 100) that has a film that selectively reflects image light of a specific polarization and is provided on a transparent member 100, and then enters the retroreflector 2. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflector 2. The image light passes through the λ / 4 plate 21 twice, once when it enters the retroreflector 2 and once when it exits, thereby undergoing polarization conversion from the specific polarization to the other polarization. Here, the polarization separator 101 that selectively reflects image light of a specific polarization has the property of transmitting the polarized light of the other polarization that has been polarization-converted, so the image light of the specific polarization after polarization conversion passes through the polarization separator 101. The image light that has passed through the polarization separator 101 forms a space-floating image 3, which is a real image, outside the transparent member 100. 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.

[0018] Here, a first example of polarization design for the optical system of FIG. 2A will be described. For example, S-polarized (S stands for Senkrecht; polarized light whose electric field oscillates perpendicular to the plane of incidence) image light may be emitted from display device 1 to polarization separator 101, which may have the property of reflecting S-polarized light and transmitting P-polarized (P stands for parallel; polarized light whose electric field oscillates within the plane of incidence) light. In this case, the S-polarized image light reaching polarization separator 101 from display device 1 is reflected by polarization separator 101 and travels toward retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, and is therefore converted from S-polarized to P-polarized light. The P-polarized image light then travels toward polarization separator 101 again. 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 that passes through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a space-floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 relative to the polarization separation member 101. This polarization design allows the space-floating image 3 to be formed optimally.

[0019] Next, a second example of polarization design for the optical system of FIG. 2A will be described. For example, P-polarized image light may be emitted from display device 1 to polarization separator 101, which may have the property of reflecting P-polarized light and transmitting S-polarized light. In this case, the P-polarized image light reaching polarization separator 101 from display device 1 is reflected by polarization separator 101 and travels toward retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, converting the P-polarized light to S-polarized light. The S-polarized image light then travels back toward polarization separator 101. Here, polarization separator 101 has the property of reflecting P-polarized light and transmitting S-polarized light, so the S-polarized image light passes through polarization separator 101 and then through transparent member 100. The image light transmitted through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 relative to the polarization separation member 101. This polarization design allows the floating image 3 to be formed optimally.

[0020] The light that forms the floating image 3 is a collection of light rays that converge from the retroreflector 2 to the optical image of the floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is a highly directional image, unlike the diffused image light formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2A, when a user views the floating image 3 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be perceived as an image at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0021] Depending on the performance of the retroreflector 2, the polarization axis of the reflected image light may become irregular. The reflection angle may also become irregular. Such irregular light may not maintain the polarization state and propagation angle assumed in the design. For example, light with an unintended polarization state and propagation angle may re-enter the image display surface of the liquid crystal display panel 11 directly from the position of the retroreflector 2 without passing through a polarization separation member. Such light with an unintended polarization state and propagation angle may re-enter the image display surface of the liquid crystal display panel 11 after being reflected by components within the space-floating image display device. Such light re-entering the image display surface of the liquid crystal display panel 11 may be re-reflected by the image display surface of the liquid crystal display panel 11 constituting the display device 1, potentially generating ghost images and degrading the image quality of the space-floating image. Therefore, in this embodiment, an absorbing polarizer 12 may be provided on the image display surface of the display device 1. The image light emitted from the display device 1 is transmitted through the absorptive polarizer 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorptive polarizer 12, thereby suppressing the re-reflection. This makes it possible to prevent degradation of image quality due to ghost images of spatially floating images. Specifically, if the display device 1 is configured to emit S-polarized image light to the polarization separation member 101, the absorptive polarizer 12 may be a polarizer that absorbs P-polarized light. Furthermore, if the display device 1 is configured to emit P-polarized image light to the polarization separation member 101, the absorptive polarizer 12 may be a polarizer that absorbs S-polarized light.

[0022] 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.

[0023] Next, Fig. 2A(2) shows an example of the surface shape of a typical retroreflector 2. A prism body with a regularly arranged array of triangular pyramidal recessed reflective surfaces is arranged on the retroreflector 2. Light rays incident on the arranged triangular pyramidal recesses are reflected by the multiple reflective surfaces of the triangular pyramidal recesses and emitted as retroreflected light in a direction corresponding to the incident light, and a real floating image is displayed based on the image displayed on the display device 1.

[0024] 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 that are periodically arranged in the form of triangular pyramidal prisms, hexagonal pyramidal prisms, other polygonal prisms, multi-vertex prisms, or combinations thereof.

[0025] Alternatively, retroreflective elements formed by periodically arranging these prisms to form cube corners may be provided on the surface of the retroreflector of this embodiment. These may also be referred to as corner reflector arrays or polyhedral reflector arrays.

[0026] Alternatively, capsule lens-type retroreflective elements with periodically arranged glass beads may be provided on the surface of the retroreflector of this embodiment. The detailed configuration of these retroreflective elements can be achieved using existing technology, so a detailed description will be omitted. Specifically, the technology disclosed in JP 2001-33609 A, JP 2001-264525 A, JP 2005-181555 A, JP 2008-70898 A, JP 2009-229942 A, etc. can be used.

[0027] <Another configuration example 1 of the optical system of the space floating image display device> Another example of the configuration of the optical system of the space floating image display device will be explained using Fig. 2B. In Fig. 2B, components with the same reference numerals as Fig. 2A have the same functions and configurations as Fig. 2A. For the sake of simplicity, repeated explanations of such components will be omitted.

[0028] In the optical system of FIG. 2B, as in FIG. 2A, image light of a specific polarization is output from the display device 1. The image light of a specific polarization output from the display device 1 is input to a polarization separator 101B. The polarization separator 101B is a member that selectively transmits image light of a specific polarization. Unlike the polarization separator 101 of FIG. 2A, the polarization separator 101B is not integrated with the transparent member 100 but has an independent plate-like shape. Therefore, the polarization separator 101B may also be referred to as a polarization separator plate. The polarization separator 101B may be configured as a reflective polarizer configured by attaching a polarization separator sheet to a transparent member. Alternatively, the transparent member may be formed of a metal multilayer film that selectively transmits specific polarization and reflects polarization of other specific polarizations. In FIG. 2B, the polarization separator 101B is configured to transmit image light of a specific polarization output from the display device 1.

[0029] 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.

[0030] Here, a first example of polarization design for the optical system of FIG. 2B will be described. For example, a configuration may be adopted in which P-polarized image light is emitted from display device 1 to polarization separator 101B, and polarization separator 101B has the property of reflecting S-polarized light and transmitting P-polarized light. In this case, the P-polarized image light that reaches polarization separator 101B from display device 1 passes through polarization separator 101B and proceeds to retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, 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 polarization separator 101B. Here, polarization separator 101B has the property of reflecting S-polarized light and transmitting P-polarized light, so the S-polarized image light is reflected by polarization separator 101 and passes through transparent member 100. The image light transmitted through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a space-floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 relative to the polarization separation member 101B. This polarization design allows the space-floating image 3 to be formed optimally.

[0031] Next, a second example of polarization design for the optical system of FIG. 2B will be described. For example, S-polarized image light may be emitted from display device 1 to polarization separator 101B, which may have the property of reflecting P-polarized light and transmitting S-polarized light. In this case, the S-polarized image light reaching polarization separator 101B from display device 1 passes through polarization separator 101B and proceeds to retroreflector 2. When the image light is reflected by retroreflector 2, it passes twice through λ / 4 plate 21 provided on the incident surface of retroreflector 2, converting the image light from S-polarized light to P-polarized light. The P-polarized image light then proceeds again to polarization separator 101B. Here, polarization separator 101B has the property of reflecting P-polarized light and transmitting S-polarized light, so the P-polarized image light is reflected by polarization separator 101 and passes through transparent member 100. The image light transmitted through the transparent member 100 is light generated by the retroreflector 2, and therefore forms a space-floating image 3, which is an optical image of the image displayed on the display device 1, at a position that is in a mirror relationship with the image displayed on the display device 1 relative to the polarization separation member 101B. This polarization design allows the space-floating image 3 to be formed optimally.

[0032] In FIG. 2B , the image display surface of the display device 1 and the surface of the retroreflector 2 are arranged parallel to each other. The polarization separator 101B is arranged tilted at an angle α (e.g., 30°) relative to the image display surface of the display device 1 and the surface of the retroreflector 2. When the polarization separator 101B reflects the image light, the direction of the image light reflected by the polarization separator 101B (the direction of the chief ray of the image light) differs by an angle β (e.g., 60°) from the direction of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light). With this configuration, the optical system of FIG. 2B outputs the image light toward the outside of the transparent member 100 at a predetermined angle shown in the figure, forming the space-floating image 3, which is a real image. In the configuration of FIG. 2B , when a user views the space-floating image 3 from the direction of arrow A, the space-floating image 3 is perceived as a bright image. However, when another person views the space-floating image 3 from the direction of arrow B, the space-floating image 3 cannot be perceived as an image at all. This characteristic is extremely suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0033] 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.

[0034] An absorptive polarizing plate may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. This absorptive polarizing plate may transmit the polarized waves of the image light from the polarization separation member 101B and absorb the polarized waves that are 90° out of phase with the polarized waves of the image light from the polarization separation member 101B. In this way, the image light for forming the space-floating image 3 can be sufficiently transmitted while reducing the external light incident on the space-floating image 3 side of the transparent member 100 by approximately 50%. This makes it possible to reduce stray light in the optical system of FIG. 2B due to the external light incident on the space-floating image 3 side of the transparent member 100.

[0035] <Another configuration example 2 of the optical system of the space floating image display device> Another example of the configuration of the optical system of the space floating image display device will be explained using Fig. 2C. In Fig. 2C, components with the same reference numerals as Fig. 2B have the same functions and configurations as Fig. 2B. For the sake of simplicity, such components will not be described repeatedly.

[0036] The only difference between the optical system in Figure 2B and the optical system in Figure 2C is the angle at which the polarization separation member 101B is disposed relative to the image display surface of the display device 1 and the surface of the retroreflector 2. All other configurations are the same as those of the optical system in Figure 2B, so repeated explanations will be omitted. The polarization design of the optical system in Figure 2C is also the same as that of the optical system in Figure 2B, so repeated explanations will be omitted.

[0037] In the optical system of FIG. 2C , the polarization separator 101B is tilted at an angle α with respect to the image display surface of the display device 1 and the surface of the retroreflector 2. In FIG. 2C , the angle α is 45°. With this configuration, when the polarization separator 101B reflects, the angle β between the direction of propagation of the image light incident from the retroreflector 2 (the direction of the chief ray of the image light) and the direction of propagation of the image light reflected by the polarization separator 101B (the direction of the chief ray of the image light) is 90°. With this configuration, the image display surface of the display device 1 and the surface of the retroreflector 2 are perpendicular to the direction of propagation of the image light reflected by the polarization separator 101B, simplifying the angular relationships of the surfaces that make up the optical system. By arranging the surface of the transparent member 100 so that it is perpendicular to the direction of propagation of the image light reflected by the polarization separator 101B, the angular relationships of the surfaces that make up the optical system can be further simplified. In the configuration of Figure 2C, when a user views the floating image 3 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be seen as an image at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0038] 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.

[0039] An absorptive polarizer may be provided on the surface of the transparent member 100 facing the polarization separation member 101B. This absorptive polarizer may transmit the polarized waves of the image light from the polarization separation member 101B and absorb the polarized waves that are 90° out of phase with the polarized waves of the image light from the polarization separation member 101B. This allows the image light for forming the space-floating image 3 to be sufficiently transmitted while reducing the external light incident on the space-floating image 3 side of the transparent member 100 by approximately 50%. This allows the stray light in the optical system of FIG. 2C due to the external light incident on the space-floating image 3 side of the transparent member 100 to be reduced.

[0040] <Another configuration example 3 of the optical system of the space floating image display device> Another example of the configuration of the optical system of the space floating image display device will be described with reference to FIG. 2D. The optical system of FIG. 2D is an optical system that uses a retroreflector 5 that is different from the retroreflector 2 used in FIGS. 2A to 2C. Hereinafter, another example of the configuration 3 of the optical system will be described in more detail with reference to FIGS. 2D to 2I. In FIG. 2D, components that are given the same reference numerals as those in FIGS. 2A to 2C have the same functions and configurations as those in FIGS. 2A to 2C. For the sake of simplicity, such components will not be described repeatedly.

[0041] 2D is a diagram showing an example of the main components and retroreflection components of a space floating image display device according to one embodiment of the present invention. A display device 1 that emits image light is provided obliquely on 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 light.

[0042] A chief ray 9020 representing the light beam emitted from the display device 1 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°.

[0043] 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.

[0044] 2E, 2F, etc., the principal ray 9020 travels in the z direction while being retroreflected in the x and y directions by the retroreflector 5. As a result, the reflected ray 9021 travels in a direction away from the retroreflector 5 along an optical path 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 spatial floating image 3 as a real image on the imaging plane.

[0045] The light beam that forms the floating image 3 is a collection of light rays that converge from the retroreflector 5 to the optical image of the floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the floating image 3. Therefore, the 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 Figure 2, when a user views the floating image 3 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be perceived as an image at all. This characteristic is 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.

[0046] 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 multiple corner reflectors 9040 are arranged in an array on the surface of a transparent member. 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 returns to the same direction as the incident direction (traveling in a direction rotated 180 degrees). In the z direction, total reflection results in specular reflection, where the angle of incidence and the angle of reflection match.

[0047] That is, light rays 9111 to 9114 generate reflected light rays 9121 to 9124 on straight lines symmetrical in the z direction with respect to corner reflector 9040, and form aerial real image 9120. Note that light rays 9111 to 9114 emitted from light source 9110 are four light rays that represent the diffused light from light source 9110, and although the light rays incident on retroreflector 5 are not limited to these four light rays depending on the diffusion characteristics of light source 9110, all incident light rays cause similar reflections and form aerial real image 9120. Note that for ease of viewing the drawing, the position of light source 9110 and the position of aerial real image 9120 are shown shifted in the x direction, but in reality, the position of light source 9110 and the position of aerial real image 9120 in the x direction are the same and are overlapping when viewed from the z direction.

[0048] 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 faces being mirror surfaces 9041 and 9042, and the other four faces being made of transparent materials. The retroreflector 5 has a configuration in which these corner reflectors 9040 are arrayed so that corresponding mirror surfaces face in the same direction.

[0049] When viewed from the top (+z direction), a light ray 9111 emitted from a light source 9110 enters the mirror surface 9041 (or the mirror surface 9042) at a specific angle of incidence, is totally reflected at a reflection point 9130, and then is totally reflected again at a reflection point 9132 on the mirror surface 9042 (or the mirror surface 9041).

[0050] 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 is rotated by 2θ after the first reflection and by 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 is rotated by 2×φ after one reflection with respect to light ray 9111.

[0051] As described above, light rays incident on the corner reflector 9040 undergo retroreflection, which creates 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 reflections occur 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.

[0052] 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 beam is located. The convergent reflected light beam forms an image in the air, forming a space-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 incident on the retroreflector 2.

[0053] In contrast, in the optical system of Fig. 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.

[0054] 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 continue to travel in a straight line, unchanged before and after reflection by the corner reflector array.

[0055] 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.

[0056] The resolution of the space-floating image formed by the light beams from the display device 1 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.

[0057] 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 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 caused by the retroreflective plate and the pixels of the liquid crystal display panel, it is advisable to design the pitch ratio of each to be a different integer multiple of one pixel. Also, it is advisable to arrange the shape so that none of the sides of the retroreflective portion overlaps with any of the sides of one pixel of the liquid crystal display panel.

[0058] 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, a corner reflector array, a slit mirror array, a dihedral corner reflector array, a polyhedral reflector array, or a shape in which a combination of these reflective surfaces is periodically arranged. Alternatively, a capsule lens-type retroreflector element with periodically arranged glass beads may be provided on the surface of the retroreflector according to this embodiment. The detailed configuration of these retroreflectors can be achieved using existing technology, so 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.

[0059] 2D, the image light emitted from the display device 1 may be in any polarization state, either S-polarized or P-polarized.

[0060] As explained above, the optical system of Figure 2D is an optical system that uses a retroreflector different from the optical systems of Figures 2A to 2C, but it can form a more suitable floating image in space, similar to the optical systems of Figures 2A to 2C.

[0061] According to the optical systems of FIGS. 2A, 2B, 2C, and 2D described above, it is possible to provide brighter, higher quality floating images in space.

[0062] <<Block diagram of the internal configuration of the space floating image display device>> Next, a description will be given of a block diagram of the internal configuration of the space-floating image display device 1000. Fig. 3 is a block diagram showing an example of the internal configuration of the space-floating image display device 1000.

[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. The imaging unit 1180 and the mid-air operation detection sensor 1351 shown in FIG.

[0065] The retroreflector 1101 in Fig. 3 corresponds to the retroreflector 2 in Figs. 2A, 2B, and 2C. The retroreflector 1101 retroreflects light modulated by the image display unit 1102. Of the light reflected from the retroreflector 1101, the light output to the outside of the space-floating image display device 1000 forms the space-floating image 3. When the optical system in Fig. 2D is applied, the retroreflector 1101 corresponds to the retroreflector 5 in Fig. 2D.

[0066] 3 corresponds to the liquid crystal display panel 11 in FIGS. 2A, 2B, and 2C. The light source 1105 in FIG. 3 corresponds to the light source device 13 in FIGS. 2A, 2B, and 2C. The image display unit 1102, the light guide 1104, and the light source 1105 in FIG. 3 correspond to the display device 1 in FIGS. 2A, 2B, and 2C.

[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 (the above-described liquid crystal display panel 11) may be, for example, a transmissive liquid crystal panel, but is not limited to this. Alternatively, the video display unit 1102 may be, for example, a reflective liquid crystal panel that modulates reflected light, a DMD (Digital Micromirror Device: registered trademark) panel, or the like.

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

[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 an operating object such as a user's finger. 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 laser, ultrasonic waves, etc. The aerial operation detection sensor 1351 may also be configured to detect coordinates on a two-dimensional plane by combining multiple sensors. The aerial operation detection sensor 1351 may also be configured with a ToF (Time of Flight) LiDAR (Light Detection and Ranging) or an image sensor.

[0072] The mid-air operation detection sensor 1351 only needs to be capable of sensing to detect touch operations with the user's finger on objects 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, based on the sensing signal, determines whether or not the user's finger has made contact with an object in the floating in space image 3, and calculates the position (contact position) where the user's finger has made contact with the object. The aerial operation detection unit 1350 is configured, for example, by a circuit such as an FPGA (Field Programmable Gate Array). Furthermore, some of the functions of the aerial operation detection unit 1350 may be realized by software, for example, by a program for detecting aerial operation executed by the control unit 1110 or the image control unit 1160. The aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be configured as an integrated unit. The aerial operation detection unit 1350 and the control unit 1110 or the image control unit 1160 may be configured as an integrated unit.

[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 a separate entity from the space-floating image display device 1000. When provided as a separate entity from the space-floating image display device 1000, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 are configured to be able to transmit information and signals to the space-floating image display device 1000 via a wired or wireless communication connection path or a video signal transmission path. This makes it possible to build a system in which the space-floating image display device 1000, which does not have aerial operation detection function, is used as the main body, and only the aerial operation detection function can be added as an option.

[0075] Also, the aerial operation detection sensor 1351 may be a separate unit, and the aerial operation detection unit 1350 may be built into the space-floating image display device 1000. In cases where it is desired to more freely arrange the aerial operation detection sensor 1351 relative to the installation position of the space-floating image display device 1000, there is an advantage to a configuration in which only the aerial operation detection sensor 1351 is a separate unit.

[0076] The imaging unit 1180 is a camera with an image sensor, and captures images of the space near the space-floating image 3 and / or the face, arms, fingers, etc. of the user 230. A plurality of imaging units 1180 may be provided. For example, the imaging unit 1180 may be provided as a stereo camera. 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 space-floating image 3 by the user 230. The imaging unit 1180 may be provided separately from the space-floating image display device 1000. When the imaging unit 1180 is provided separately from the space-floating image display device 1000, it is sufficient to configure it so that an imaging signal can be transmitted to the space-floating 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 (display range) of the spatial floating image 3 and detects whether or not an object has intruded into this intrusion detection plane, the aerial operation detection sensor 1351 may not be able to detect information such as how far an object (e.g., a user's finger) that has not intruded into the intrusion detection plane is from the intrusion detection plane, or how close the object is to the intrusion detection plane.

[0078] In such a case, the distance between the object and the intrusion detection plane (space floating image 3) can be calculated by using information such as object depth calculation information based on captured images from the multiple imaging units 1180 and object depth information from a depth sensor. Then, various information such as this depth calculation information, depth information, and distance between the object and the intrusion detection plane is used for various display controls for the space floating 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 of the imaging unit 1180. In this case, the imaging unit 1180 may be referred to as an aerial operation detection sensor.

[0080] Furthermore, the imaging unit 1180 may capture an image of the face of the user operating the space-floating image 3, and the control unit 1110 or the like may perform a process to identify the user. Furthermore, in order to determine whether or not there is another person standing around or behind the user operating the space-floating image 3 and peeking at the user's operation of the space-floating image 3, the imaging unit 1180 may capture an image of the user operating the space-floating image 3 and a range including the user's surrounding area.

[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 user's air operation (touch operation). Apart from the above-mentioned user 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 (video signals). The video signal input unit 1131 can be implemented using various digital video input interfaces. For example, it may be configured with a video input interface conforming to the HDMI (registered trademark) (High-Definition Multimedia Interface) standard, a video input interface conforming to the DVI (Digital Visual Interface) standard, or a video input interface conforming to the DisplayPort standard. Alternatively, an analog video input interface such as analog RGB or composite video may be provided.

[0083] The audio signal input unit 1133 is connected to an external audio output device and inputs audio data (audio signals). The audio signal input unit 1133 may be configured as an audio input interface conforming to the HDMI standard, an optical digital terminal interface, a coaxial digital terminal interface, or the like. In the case of an interface conforming to the HDMI standard, the video signal input unit 1131 and the audio signal input unit 1133 may be configured as an interface in which a terminal and a cable are integrated.

[0084] The audio output unit 1140 can output audio based on audio data input to the audio signal input unit 1133. The audio output unit 1140 may be configured with a speaker 1140. The audio output unit 1140 may also include a section that performs voice synthesis processing, etc. The audio output unit 1140 may also output built-in operation sounds and 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.

[0085] The audio input unit 1139 may be configured with a microphone 1139. 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 or the like performs voice recognition processing on the generated audio signal to obtain text information from the audio signal. The audio input unit 1139 may be provided with a part that performs voice recognition processing or the like. Note that the audio output unit 1140, the audio input unit 1139, etc. may be connected as external devices to the space-floating image display device 1000.

[0086] The nonvolatile memory 1108 stores various data used by the space-floating image display device 1000. The data stored in the nonvolatile memory 1108 includes, for example, data for various operations to be displayed on the space-floating image 3, display icons, data of objects for the user to operate, layout information, etc. The memory 1109 stores image data to be displayed as the space-floating image 3, data for controlling the device, etc.

[0087] The control unit 1110 includes a processor and controls the operation of each connected unit. The control unit 1110 may also work in cooperation 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.

[0088] The communication unit 1132 communicates with external devices, external servers, etc. via a wired or wireless communication interface. If the communication unit 1132 has a wired communication interface, the wired communication interface may be configured, for example, as an Ethernet LAN interface. If the communication unit 1132 has a wireless communication interface, the interface may be configured, for example, as a Wi-Fi communication interface, a Bluetooth communication interface, or a mobile communication interface such as 4G or 5G. Various types of data, such as video data, image data, and audio data, are transmitted and received through communication via the communication unit 1132.

[0089] 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.

[0090] The storage unit 1170 is a storage device that records various types of information such as video data, image data, audio data, etc. The storage unit 1170 may be configured with a magnetic recording medium recording device such as a hard disk drive (HDD), or a semiconductor element memory such as a solid state drive (SSD). For example, various types of information such as video data, image data, audio data, etc. may be recorded in advance in the storage unit 1170 at the time of product shipment. Furthermore, the storage unit 1170 may record various types of information such as video data, image data, audio data, etc. acquired from an external device, an external server, etc. via the communication unit 1132.

[0091] 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 based on processing by the video control unit 1160. Video data, image data, etc. of display icons, objects for user operation, etc. displayed as the space floating image 3 are also recorded in the storage unit 1170. Layout information of the display icons, objects, etc. displayed as the space floating image 3, and various metadata information related to the objects, etc. are also recorded in the storage unit 1170.

[0092] The audio data recorded in the storage unit 1170 is output as audio from the audio output unit 1140, for example.

[0093] The video control unit 1160 performs various controls related to the video signal input to the video display unit 1102. Based on the video signal (video data), the video control unit 1160 creates a video signal (display data) for displaying a video on the video display unit 1102 (for example, the liquid crystal display panel 11 of the display device 1 described above), and supplies the video signal 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 performs video switching control, 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.

[0094] Note that the control unit 1110 may perform the same processing as the video control unit 1160, in which case the control unit 1110 may be referred to as a video processing unit, etc. At least one of the control unit 1110, the video control unit 1160, the aerial operation detection unit 1360, etc. may perform unique control processing, in which case the control unit 1110, the video control unit 1160, the aerial operation detection unit 1360, etc. may be referred to as a video processing unit.

[0095] In addition, the video control unit 1160 may generate a superimposed video signal by superimposing the video signal to be stored in the memory 1109 and the video signal input from the video signal input unit 1131, and input the superimposed video signal to the video display unit 1102, thereby performing control to form the composite video as the floating-in-space video 3.

[0096] Furthermore, the video control unit 1160 may control image processing of the video signal input from the video signal input unit 1131, the video signal to be stored in the memory 1109, etc. Examples of image processing include scaling processing to enlarge, reduce, deform, etc. the image, brightness adjustment processing to change the brightness, contrast adjustment processing to change the contrast curve of the image, and Retinex processing to decompose the image into light components and change the weighting of each component.

[0097] Furthermore, the video control unit 1160 may perform special effect video processing or the like to assist the user's mid-air operation (touch operation) on the video signal input to the video display unit 1102. The special effect video processing is performed, for example, based on the detection result of the user's touch operation by the mid-air operation detection unit 1350, or on the image of the user captured by the imaging unit 1180. Furthermore, the video control unit 1160 or the like may perform audio control processing when audio is output from the audio output unit 1140 simultaneously with the floating-in-space video 3. An audio control unit for this audio control processing may be provided separately from the video control unit 1160.

[0098] The attitude sensor 1113 is a sensor configured by a gravity sensor or an acceleration sensor, or a combination of these, and can detect the attitude in which the space-floating image display device 1000 is installed. Based on the attitude detection result of the attitude sensor 1113, the control unit 1110 may control the operation of each connected unit. For example, when an undesirable attitude in the user's usage state is detected, the control unit 1110 may perform control such that the image being displayed on the image display unit 1102 is stopped and an error message is displayed to the user. Alternatively, when the attitude sensor 1113 detects a change in the installation attitude of the space-floating image display device 1000, the control unit 1110 may perform control such that the display direction of the image being displayed on the image display unit 1102 is rotated.

[0099] 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.

[0100] <Configuration example of a space floating image display device> Next, a configuration example of the space-floating image display device will be described. The layout of the components of the space-floating image display device according to this embodiment can be various depending on the usage form. Below, the layouts of each of Figs. 4A to 4P will be described. In addition, in each example of Figs. 4A to 4P, the thick lines surrounding the components (display device 1, etc.) of the space-floating image display device 1000 show an example of the housing structure (housing 1190 in Fig. 3) of the space-floating image display device 1000.

[0101] FIG. 4A is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4A is equipped with an optical system corresponding to the optical system of FIG. 2A. The space-floating image display device 1000 shown in FIG. 4A is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4A, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. When the mid-air operation detection sensor 1351 is installed as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230. Note that the x direction is the left-right direction as seen from the user, the y direction is the front-back direction (depth direction) as seen from the user, and the z direction is the up-down direction (vertical direction). Hereinafter, the definitions of the x direction, y direction, and z direction are the same in each drawing of FIG. 4, so repeated explanations will be omitted.

[0102] FIG. 4B is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4B is equipped with an optical system corresponding to the optical system of FIG. 2A. The space-floating image display device 1000 shown in FIG. 4B is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (toward the user 230). That is, in FIG. 4B, the space-floating image display device is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230. 4B, the mid-air operation detection sensor 1351 can use the reflection of sensing light by the user's nail for touch detection by sensing the finger of the user 230 from above. Generally, the reflectivity of the nail is higher than that of the finger pad, so this configuration can improve the accuracy of touch detection.

[0103] FIG. 4C is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4C is equipped with an optical system corresponding to the optical system of FIG. 2B. The space-floating image display device 1000 shown in FIG. 4C is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4C, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the user's 230 finger.

[0104] FIG. 4D is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4D is equipped with an optical system corresponding to the optical system of FIG. 2B. The space-floating image display device 1000 shown in FIG. 4D is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (toward the user 230). That is, in FIG. 4D, the space-floating image display device 1000 is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the user 230's finger. 4D, the mid-air operation detection sensor 1351 can use the reflection of sensing light by the user's nail for touch detection by sensing the finger of the user 230 from above. Generally, the reflectivity of the nail is higher than that of the finger pad, so this configuration can improve the accuracy of touch detection.

[0105] FIG. 4E is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4E is equipped with an optical system corresponding to the optical system of FIG. 2C. The space-floating image display device 1000 shown in FIG. 4E is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward. That is, in FIG. 4E, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels directly upward. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0106] FIG. 4F is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4F is equipped with an optical system corresponding to the optical system of FIG. 2C. The space-floating image display device 1000 shown in FIG. 4F is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (toward the user 230). That is, in FIG. 4F, the space-floating image display device 1000 is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels toward the user. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the user 230's finger.

[0107] FIG. 4G is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4G is equipped with an optical system corresponding to the optical system shown in FIG. 2C. In the optical systems of the space-floating image display devices shown in FIGS. 4A to 4F, the central optical path of the image light emitted from the display device 1 was on the yz plane. That is, in the optical systems of the space-floating image display devices shown in FIGS. 4A to 4F, the image light traveled in the front-to-back and up-to-down directions as seen from the user. In contrast, in the optical system of the space-floating image display device shown in FIG. 4G, the central optical path of the image light emitted from the display device 1 is on the xy plane. That is, in the optical system of the space-floating image display device shown in FIG. 4G, the image light travels in the left-to-right and front-to-back directions as seen from the user. The space-floating image display device 1000 shown in FIG. 4G is installed so that the surface on which the space-floating image 3 is formed faces the front of the device (toward the user 230). That is, in Fig. 4G, the space-floating image display device 1000 has the transparent member 100 installed on the front side of the device (toward the user 230). The space-floating image 3 is formed on the user side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels towards the user. If the mid-air operation detection sensor 1351 is installed as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0108] FIG. 4H is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of FIG. 4H differs from the space-floating image display device of FIG. 4G in that it has a window with a transparent plate 100B made of glass or plastic on the back of the device (opposite the position where the user 230 views the space-floating image 3, i.e., opposite the traveling direction of the image light of the space-floating image 3 toward the user 230). The rest of the configuration is the same as that of the space-floating image display device of FIG. 4G, so repeated explanations will be omitted. The space-floating image display device 1000 of FIG. 4H has a window with a transparent plate 100B on the opposite side of the traveling direction of the image light of the space-floating image 3 from the space-floating image 3. Therefore, when the user 230 views the space-floating image 3, they can recognize the scenery behind the space-floating image display device 1000 as the background of the space-floating image 3. Therefore, the user 230 can perceive the space floating image 3 as floating in the air in front of the scenery behind the space floating image display device 1000. This can further emphasize the floating feeling of the space floating image 3.

[0109] 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 may be visually recognized by the user 230 as stray light. Therefore, in order to prevent this stray light, the transparent plate 100B may not be provided at the window on the back of the space-floating image display device 1000.

[0110] 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 is different 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 other configurations are the same as those of the space-floating image display device of Fig. 4H, so repeated explanations will be omitted.

[0111] 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.

[0112] For example, when the view seen through the window of the transparent plate 100B of the space-floating image display device 1000 is outdoors, the brightness of sunlight varies depending on the weather. When the outdoor sunlight is strong, the background of the space-floating image 3 may become too bright, reducing the user 230's visibility of the space-floating image 3. In such a case, by moving (sliding), rotating, or attaching the light blocking plate of the opening / closing door 1410 to block the light from the rear window, the background of the space-floating image 3 becomes dark, thereby relatively increasing the visibility of the space-floating image 3. Such a blocking operation by the light blocking plate of the opening / closing door 1410 may be performed directly by the force of the user 230's hand. In response to an operation input via the operation input unit 1107 of FIG. 3, the control unit 1110 may control a motor (not shown) to perform the blocking operation by the light blocking plate of the opening / closing door 1410.

[0113] An illuminance sensor may be provided on the rear side (opposite the user 230) of the space-floating image display device 1000, such as near the rear window, to measure the brightness of the space beyond the rear window. In this case, the control unit 1110 of Fig. 3 may control a motor (not shown) to perform the opening and closing operation of the light blocking plate of the opening and closing door 1410 according to the detection result of the illuminance sensor. By controlling the opening and closing operation of the light blocking plate of the opening and closing door 1410 in this way, it becomes possible to more suitably maintain the visibility of the space-floating image 3, even if the user 230 does not manually open and close the light blocking plate of the opening and closing door 1410.

[0114] Furthermore, the light blocking plate by the opening and closing door 1410 may be manually detachable. Depending on the intended use and installation environment of the space floating image display device 1000, the user can select whether to leave the rear window open or in a light blocking state. If it is planned to use the rear window in a light blocking state for a long period of time, the detachable light blocking plate can be fixed in the light blocking state. Also, if it is planned to use the rear window in an open state for a long period of time, it can be used with the detachable light blocking plate removed. The light blocking plate may be attached and detached using screws, a hook structure, or a fitting structure.

[0115] Even in the example of the space-floating image display device 1000 shown in FIG. 4I, depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separator 101B, a portion of the image light output from the display device 1 may be reflected by the polarization separator 101B and directed toward the transparent plate 100B. Depending on the coating performance of the surface of the transparent plate 100B, this light may be reflected again by the surface of the transparent plate 100B and be visible to the user 230 as stray light. Therefore, to prevent this stray light, the window on the back of the space-floating image display device 1000 may not be provided with 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.

[0116] FIG. 4J is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of FIG. 4J differs from the space-floating image display device of FIG. 4H in that instead of the transparent plate 100B made of glass or plastic being placed on the rear side window, an electronically controlled transmittance variable device 1620 is placed. The other components 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. Although the electronically controlled transmittance variable device 1620 is not shown in FIG. 3, if it is provided, it may be configured as one component of the space-floating image display device 1000 of FIG. 3 and connected to other processing units such as the control unit 1110.

[0117] The liquid crystal shutter can control the light transmittance by controlling the voltage of the liquid crystal element sandwiched between two polarizing plates. Therefore, if the liquid crystal shutter is controlled to increase the transmittance, the scenery through the rear window can be seen through the background of the floating image 3. On the other hand, if the liquid crystal shutter is controlled to decrease the transmittance, the scenery through the rear window can be hidden as the background of the floating image 3.

[0118] Furthermore, because the liquid crystal shutter can control halftones, it can also be set to a state of transmittance of 50% or the like. For example, the control unit 1110 can control the transmittance of the electronically controlled transmittance variable device 1620 in response to an operation input via the operation input unit 1107 in Fig. 3. With this configuration, in cases where a viewer wants to see the scenery through the rear window as the background of the Space Floating Image 3, but the scenery through the rear window as the background is too bright and reduces the visibility of the Space Floating Image 3, it is possible to adjust the transmittance of the electronically controlled transmittance variable device 1620 and thereby adjust the visibility of the Space Floating Image 3.

[0119] In addition, an illuminance sensor may be provided on the back side (opposite the user 230) of the space-floating image display device 1000, such as near the rear window, to measure the brightness of the space beyond the rear window. In this case, the control unit 1110 in Fig. 3 controls the transmittance of the electronically controlled transmittance variable device 1620 according to the detection result of the illuminance sensor. In this way, even if the user 230 does not perform an operation input via the operation input unit 1107 in Fig. 3, the transmittance of the electronically controlled transmittance variable device 1620 can be adjusted according to the brightness of the space beyond the rear window, making it possible to more suitably maintain the visibility of the space-floating image 3.

[0120] In the above example, a liquid crystal shutter has been described as an example of the electronically controlled variable transmittance device 1620. However, electronic paper may be used as another example of the electronically controlled variable transmittance device 1620. The same effects as those described above can be obtained when electronic paper is used. Furthermore, electronic paper consumes very little power to maintain a halftone state. Therefore, a space floating image display device with lower power consumption can be realized compared to when a liquid crystal shutter is used.

[0121] 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.

[0122] In the space-floating image display device 1000 of FIG. 4K, a light beam of an image passes through the display surface of the transmissive self-luminous image display device 1650, and then a space-floating image 3 is formed outside the space-floating image display device 1000. That is, when an image is displayed on the transmissive self-luminous image display device 1650, which is a two-dimensional flat display, the space-floating image 3 can be displayed as a pop-up image further in front of the image displayed on the transmissive self-luminous image display device 1650. In this case, the user 230 can simultaneously view two images at different depth positions. The transmissive self-luminous image display device 1650 may be configured using existing technology such as a transmissive organic EL panel disclosed in, for example, Japanese Patent Application Laid-Open No. 2014-216761. When the transmissive self-luminous image display device 1650 is provided, 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.

[0123] Here, if the transmissive self-luminous video display device 1650 displays both the background and an object such as a character, and then displays only the object such as the character moving to the front of the floating video image 3, it is possible to provide the user 230 with a more effective video experience with a surprise effect.

[0124] Furthermore, if the inside of the space-floating image display device 1000 (housing 1190) 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. Note that, since the space-floating image 3 in the embodiment of the present invention is displayed as a real optical image in a space without a screen, if the light source of the display device 1 is turned off, the intended display position of the space-floating image 3 becomes empty space. Therefore, when the transmissive self-luminous image display device 1650 is used to display an image as if it were a normal two-dimensional flat display, characters, objects, etc. can be suddenly displayed in the air as the space-floating image 3, thereby providing the user 230 with a more effective surprise video experience.

[0125] Note that the darker the interior of the space-floating image display device 1000, the more the transmissive self-luminous image display device 1650 appears like a two-dimensional flat display. Therefore, an absorptive polarizer (not shown) that transmits the polarized waves of the image light reflected by the polarization separation member 101B and absorbs polarized waves that are 90° out of phase with the polarized waves may be provided on the surface of the transmissive self-luminous image display device 1650 facing the interior of the space-floating image display device 1000 (the surface where the image light reflected by the polarization separation member 101B enters the transmissive self-luminous image display device 1650, i.e., the surface of the transmissive self-luminous image display device 1650 opposite the space-floating image 3). This does not have a significant effect on the image light that forms the space-floating image 3, but it can significantly reduce the light that enters the interior of the space-floating image display device 1000 from the outside through the transmissive self-luminous image display device 1650, making the interior of the space-floating image display device 1000 darker, which is preferable.

[0126] 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.

[0127] 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.

[0128] In both the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L, the space-floating image 3 is displayed superimposed on the image of the transmissive self-luminous image display device 1650 as seen by the user 230. Here, the position of the space-floating image 3 and the position of the image of the transmissive self-luminous image display device 1650 are configured to have a difference in the depth direction. Therefore, when the user 230 moves his / her head (position of viewpoint), the user can recognize the depth of the two images due to parallax. Therefore, by displaying two images at different depth positions, a three-dimensional image experience can be more suitably provided to the user with the naked eye, without the need for stereoscopic glasses or the like.

[0129] 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 far side (for example, the back panel of the housing 1190) as seen from the user 230 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.

[0130] 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 as overlapping images. In other words, the second display device 1680 can be said to be arranged so as to display an image in the direction of the user 230 who views the space-floating image 3. When the second display device 1680 is provided, 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.

[0131] Note that the image light of the second display device 1680 of the space-floating image display device 1000 of FIG. 4M is viewed by the user 230 after passing through the polarization separator 101B. Therefore, in order for the image light of the second display device 1680 to more suitably pass through the polarization separator 101B, it is desirable that the image light output from the second display device 1680 be polarized in a vibration direction that the polarization separator 101B more suitably transmits. That is, it is desirable that the image light be polarized in the same vibration direction as the polarization of the image light output from the display device 1. For example, if the image light output from the display device 1 is S-polarized, it is desirable that the image light output from the second display device 1680 is also S-polarized. Furthermore, if the image light output from the display device 1 is P-polarized, it is desirable that the image light output from the second display device 1680 is also P-polarized.

[0132] The example of the space-floating image display device of FIG. 4M also has the same effect as the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L in that a second image is displayed behind the space-floating image 3. However, unlike the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L, in the example of the space-floating image display device of FIG. 4M, the luminous flux of image light for forming the space-floating image 3 does not pass through the second display device 1680. Therefore, the second display device 1680 does not need to be a transmissive self-luminous image display device, but may be a liquid crystal display, which is a two-dimensional flat display. The second display device 1680 may also be an organic EL display. Therefore, the example of the space-floating image display device of FIG. 4M can realize the space-floating image display device 1000 at a lower cost than the example of the space-floating image display device of FIG. 4K and the example of the space-floating image display device of FIG. 4L.

[0133] Here, depending on the polarization distribution of the image light output from the display device 1 and the performance of the polarization separation member 101B, a portion of the image light output from the display device 1 may be reflected by the polarization separation member 101B and travel toward the second display device 1680. This light (a portion of the image light) may be reflected again by the surface of the second display device 1680 and may be visually recognized by the user as stray light.

[0134] Therefore, to prevent this stray light, an absorptive polarizer may be provided on the surface of the second display device 1680. In this case, the absorptive polarizer may be an absorptive polarizer that transmits the polarized waves of the image light output from the second display device 1680 and absorbs polarized waves that are 90° out of phase with the polarized waves of the image light output from the second display device 1680. If the second display device 1680 is a liquid crystal display, an absorptive polarizer is also provided on the image output side of the liquid crystal display. However, if there is a cover glass (cover glass on the image display surface side) on the output surface of the absorptive polarizer on the image output side of the liquid crystal display, it is not possible to prevent stray light caused by reflection of the cover glass by light from outside the liquid crystal display. Therefore, it is necessary to separately provide the above-mentioned absorptive polarizer on the surface of the cover glass.

[0135] When an image is displayed on the second display device 1680, which is a two-dimensional flat display, the floating-in-space image 3 can be displayed as an image further in front of the image on the second display device 1680. In this case, the user 230 can simultaneously view two images at different depth positions. By displaying a character on the floating-in-space image 3 and a background on the second display device 1680, it is possible to provide the effect that the user 230 is viewing the space in which the character exists in three dimensions.

[0136] Furthermore, if the second display device 1680 displays both the background and an object such as a character, and then displays only the object such as the character moving to the front of the floating image 3, it is possible to provide the user 230 with a more effective surprise visual experience.

[0137] 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. In the space-floating image display device 1000 of Fig. 4N, similar to the examples of the space-floating image display device that employ the optical systems of Figs. 2A to 2C, image light that has passed through a transparent member 100 is formed in the air as a space-floating image 3. Furthermore, using sensing light from an aerial operation detection sensor 1351 that is arranged on the far 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.

[0138] In both the example of the space-floating image display device employing the optical system of FIGS. 2A to 2C and 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 located on the back side of the transparent member 100 as seen from the user.

[0139] 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 Fig. 2C is arranged on the back side of the transparent member 100 as seen from the user. However, the usability of the space-floating image display device employing the optical system of Fig. 2D as seen from the user is almost the same as that of the space-floating image display device employing the optical system of Fig. 2A to Fig. 2C.

[0140] 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.

[0141] 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. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0142] 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 do not exist in Fig. 4O. Furthermore, while the presence of an absorbing polarizer 12 is more preferable in Fig. 4A, the absorbing polarizer 12 is not particularly necessary in Fig. 4O.

[0143] 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 concept, 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.

[0144] For example, FIG. 4P 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. 4P is equipped with an optical system corresponding to the optical system shown in FIG. 2D. FIG. 4P shows the configuration of the space-floating image display device of FIG. 4B, with the optical system shown in FIG. 2A replaced with the optical system shown in FIG. 2D. The space-floating image display device 1000 shown in FIG. 4P 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. 4P, the space-floating image display device is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is installed as shown in the figure, it can detect the operation of the space-floating image 3 by the user 230's finger. 4P, the mid-air operation detection sensor 1351 can use the reflection of sensing light by the user's nail for touch detection by sensing the finger of the user 230 from above. Generally, the reflectivity of the nail is higher than that of the finger pad, so this configuration can improve the accuracy of touch detection.

[0145] According to the configuration of the space-floating image display device of FIGS. 4N to 4P, it is possible to realize a user-friendly space-floating image display device using the optical system of FIG. 2D.

[0146] <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 a liquid crystal display panel 11 as an image display element 11, and a light source device 13 that constitutes a light source for the liquid crystal display panel 11. In Fig. 5, the light source device 13 is shown together with the liquid crystal display panel 11 as an exploded perspective view.

[0147] As shown by arrow 30 in Fig. 5, the image display element 11, which is a liquid crystal display panel, receives an illumination light beam from a light source device 13, which is a backlight device, that has narrow-angle diffusion characteristics, i.e., has strong directionality (in other words, linearity) and characteristics similar to laser light with a polarization plane aligned in one direction. The image display element 11, which is a liquid crystal display panel 11, modulates the received illumination light beam in accordance with an input video signal. The modulated image light is reflected by the retroreflector 2 and passes through a transparent member 100 to form a real image, a floating image (see Fig. 1).

[0148] 5, the display device 1 is configured with a light source device 13 and a liquid crystal display panel 11, a light redirection panel 54 that controls the directional characteristics of the light beam emitted from the light source device 13, and a narrow-angle diffuser (not shown) as needed. Specifically, polarizing plates are provided on both sides of the liquid crystal display panel 11, and as indicated by arrow 30 in FIG. 5, image light of a specific polarization is emitted with its intensity modulated by a video signal. This allows a desired image to be projected as highly directional (linear) light of a specific polarization via the light redirection panel 54 toward the retroreflector 2. After being reflected by the retroreflector 2, the light is transmitted toward the eyes of a monitor outside the store (space) shown in FIG. 1, forming the floating image 3. A protective cover 50 (see FIGS. 6 and 7) may be provided on the surface of the light redirection panel 54.

[0149] <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. This light source device 13 is configured by, for example, housing LED elements 201 and a light guide 203 inside a plastic case or the like. As shown in FIG. 5 and other figures, the end surface of the light guide 203 is provided with a lens shape whose cross-sectional area gradually increases toward the light receiving section in order to convert divergent light from each LED element 201 into a substantially parallel beam. The lens shape has an effect of gradually reducing the divergence angle by multiple total reflections during propagation inside. The liquid crystal display panel 11 constituting the display device 1 is attached to the top surface of the display device 1. In addition, an LED substrate 202 mounting the LED elements 201, which are semiconductor light sources, and their control circuits is attached to one side surface 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 201 and the control circuit, may be attached to the outer surface of the LED substrate 202.

[0150] The liquid crystal display panel 11 is mounted on the top surface of the case of the light source device 13 through a frame (not shown) for the liquid crystal display panel 11. The frame is also fitted with an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. The liquid crystal display panel 11, which is the image display element 11, 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, such as an LED element.

[0151] Next, the configuration of the optical system housed in the case of light source device 13 will be described in detail with reference to Fig. 6 and Fig. 7. Because Fig. 6 and Fig. 7 are cross-sectional views, only one of the multiple LED elements 201 constituting the light source is shown, and this is converted into approximately parallel light (collimated light) by the shape of light-receiving end surface 203a of light guide 203. For this reason, the light-receiving portion of the light guide end surface and LED element 201 are attached while maintaining a predetermined positional relationship.

[0152] Each light guide 203 is formed of a translucent resin such as acrylic. The LED light receiving surface at the end of light guide 203 has a cone-shaped outer periphery obtained by rotating a parabolic cross section, and 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 LED element 201 is attached is a parabolic shape that forms a cone-shaped outer periphery, and is set within an angle range that allows total reflection within the light that is emitted from the LED element toward the periphery, or a reflective surface is formed.

[0153] 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 so that the LED elements 201 on the surface are positioned in the center of the recessed portion described above with respect to the light-receiving end surface 203a, that is, the LED collimator.

[0154] According to this configuration, the shape of the light-receiving end surface 203a of the light guide 203 makes it possible to extract the light emitted from the LED element 201 as approximately parallel light, thereby improving the efficiency of use of the generated light.

[0155] 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 203, which is guided inside the light guide 203 as shown by the arrow, and emitted by the light beam direction conversion means 204 towards the liquid crystal display panel 11, which is arranged approximately parallel to the light guide 203. By optimizing the distribution (in other words, density) of the light beam direction conversion means 204 depending on the shape of the inside or surface of the light guide 203, it is possible to control the uniformity of the light beam incident on the liquid crystal display panel 11.

[0156] The light beam direction conversion means 204 described above emits the light beam propagated inside the light guide 203 toward the liquid crystal display panel 11 disposed approximately parallel to the light guide 203, by using the shape of the surface of the light guide 203 or by providing a portion with a different refractive index inside the light guide 203. At this time, 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.

[0157] 6 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED element 201 described above. 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. Attached to the top surface of light source device 13 is liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0158] Furthermore, a film- or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects 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 (the lower surface in the figure) of the light guide 203, and directed toward the liquid crystal display panel 11. Therefore, a retardation plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49. The reflected light (reflected light beam) is reflected by the reflective sheet 205 and passes through the retardation plate (λ / 4 plate) twice, thereby converting it from P polarized light to S polarized light. This improves the utilization efficiency of the light source light as image light. The image light beam, the light intensity of which has been modulated by the image signal in the liquid crystal display panel 11, is emitted as shown by the arrow 213 in Fig. 6 and enters the retroreflector 2. After reflection by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0159] 7 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED elements 201, similar to Fig. 6. Light source device 13 is similarly composed of light guide 203 formed of, for example, plastic and having light beam direction conversion means 204 on its surface or inside, LED elements 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc. Attached to the top surface of light source device 13 is liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0160] A film- or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects 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 are different from those in FIG. 7. The reflected light is reflected by a reflective sheet 205 provided on one surface (the lower 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. The reflected light (reflected light beam) is reflected by the reflective sheet 205 and passes through the retardation plate (λ / 4 plate) twice, converting it from S-polarized light to P-polarized light. This improves the utilization efficiency of the light source light as image light. The image light beam, which has been intensity-modulated by the image signal on the liquid crystal display panel 11, is emitted as shown by the arrow 214 in Fig. 7 and enters the retroreflector 2. After being reflected by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0161] In the light source device 13 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, a 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 11. 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 devices are obtained.

[0162] <Display device example 2> 8 shows another example of the specific configuration of the display device 1. The light source device 13 of this display device 1 is configured by housing LEDs, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and a liquid crystal display panel 11 is attached to the upper surface of the light source device 13. Also, LED elements 201, which are semiconductor light sources, and an LED board 202, on which a control circuit for the LED elements 201 is 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 201 and the control circuit, is attached to the outer surface of the LED board 202.

[0163] The liquid crystal display panel frame attached to the top surface of the case of the light source device 13 is configured to have attached thereto the liquid crystal display panel 11 attached to the frame, and further to have attached thereto an FPC 403 electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is the image display element 11, generates a display image together with the LED elements 201, which are solid-state light sources, by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes the electronic device.

[0164] <Display device example 3> Next, another example of the specific configuration of the display device 1 (Example 3 of the display device) will be described with reference to Fig. 9. The light source device of this display device 1 converts a divergent beam of light (a mixture of P-polarized and S-polarized light) from the LED element 201 into a substantially parallel beam by a collimator (LED collimator) 18, and reflects the parallel beam toward the liquid crystal display panel 11 by the reflecting surface of the reflective light guide 304. The reflected light is incident on a reflective polarizer 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. The reflective polarizer 49 transmits light of a specific polarization (e.g., P-polarized light) and causes the transmitted polarized light to be incident on the liquid crystal display panel 11. Here, light of polarization other than the specific polarization (e.g., S-polarized light) is reflected by the reflective polarizer 49 and directed toward the reflective light guide 304 again.

[0165] The reflective polarizing plate 49 is installed at an angle with respect to the liquid crystal display panel 11 so that the reflective polarizing plate 49 is not perpendicular to the chief ray of light from the reflective surface of the reflective light guide 304. The chief ray of the light reflected by the reflective polarizing plate 49 is incident on the transmission surface of the reflective light guide 304. The light that has entered the transmission surface of the reflective light guide 304 passes through the back surface of the reflective light guide 304, passes through the λ / 4 plate 270 which is a retardation plate, and is reflected by the reflector 271. The light reflected by the reflector 271 passes through the λ / 4 plate 270 again, and passes through the transmission surface of the reflective light guide 304. The light that has passed through the transmission surface of the reflective light guide 304 is incident on the reflective polarizing plate 49 again.

[0166] At this time, the light that re-enters the reflective polarizer 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarization (for example, P-polarized light) that is transmitted through the reflective polarizer 49. Therefore, the light whose polarization has been converted passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Note that with regard to the polarization design related to the polarization conversion, the polarization may be configured in reverse from the above explanation (S-polarized light and P-polarized light may be reversed).

[0167] As a result, the light from the LED 201 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, there are multiple LEDs 201 that constitute the light source, and these are attached to predetermined positions relative to the corresponding collimators 18 of the multiple collimators 18. However, since Figure 9 is a vertical cross section, only one LED 201 and one collimator 18 are shown.

[0168] Each of the collimators 18 is formed of, for example, a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer peripheral surface obtained by rotating a parabolic cross section. The collimator 18 may have a concave portion with a convex portion (i.e., a convex lens surface) formed in the center of the apex (the side facing the LED substrate 202) of the collimator 18. The collimator 18 may have a convex lens surface protruding outward (or a concave lens surface recessed inward) in the center of the flat portion (the side opposite the apex). The parabolic surface forming the cone-shaped outer peripheral surface of the collimator 18 is set within an angle range that allows the light emitted from the LED 201 in the peripheral direction to be totally reflected therein, or a reflective surface is formed therein.

[0169] The LEDs 201 are arranged at predetermined positions on the surface of the LED substrate 202, which is the circuit board. The LED substrate 202 is arranged and fixed to the collimator 18 so that the LEDs 201 on the surface are positioned at the center of the apex of the conical convex shape (or in the concave portion if the apex has a concave portion).

[0170] With this configuration, the collimator 18 focuses the light emitted from the LED 201, particularly the light emitted from the central portion, into parallel light by the convex lens surface that forms the outer shape of the collimator 18. Light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the cone 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 201 as parallel light, thereby improving the utilization efficiency of the generated light.

[0171] Furthermore, the light converted into approximately parallel light by the collimator 18 shown in FIG. 9 is reflected by the reflective light guide 304. Due to the action of the reflective polarizer 49, light of a specific polarization of the light passes through the reflective polarizer 49, while light of the other polarization reflected by the reflective polarizer 49 passes through the light guide 304 again. The light is reflected by the reflector 271, which is located opposite the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarized and converted twice by passing through the λ / 4 plate 270, which is a retardation plate. The light reflected by the reflector 271 passes through the light guide 304 again and enters the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarization-converted, it passes through the reflective polarizer 49, aligns its polarization direction, and enters the liquid crystal display panel 11. As a result, all of the light from the light source can be utilized, thereby doubling the geometrical optical utilization efficiency of light. Furthermore, since the degree of polarization (extinction ratio) of the reflective polarizer 49 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. Note that the reflection diffusion angle of light at each reflective surface can be adjusted by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 can be adjusted for each design to optimize the uniformity of the light incident on the liquid crystal display panel 11.

[0172] 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, it is sufficient for the retardation plate to change the phase 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.

[0173] <Display device example 4> Furthermore, another example (display device example 4) of the configuration of the optical system such as the light source device of display device 1 will be described with reference to FIG. 10 . Display device example 4 is a configuration example in which a diffusion sheet is used instead of reflective light guide 304 in the light source device of display device example 3. Specifically, two optical sheets (in other words, diffusion sheets) that convert the diffusion characteristics in the vertical and horizontal directions of the drawing (front and back directions in the drawing, not shown) are used on the light emission side of collimator 18. The two optical sheets are shown as optical sheet 207A and optical sheet 207B. Light from collimator 18 is made to enter between the two optical sheets.

[0174] The optical sheet may be a single sheet instead of a two-sheet configuration. In the case of a single sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes on the front and back surfaces of the single optical sheet. Alternatively, multiple diffusion sheets may be used to share the functions. In the example of FIG. 10 , the reflection and diffusion characteristics due to the front and back shapes of optical sheets 207A and 207B can be optimally designed using the number of LEDs 201, the divergence angle from LED substrate 202, and the optical specifications of collimator 18 as design parameters so that the surface density of the light beam emitted from liquid crystal display panel 11 is uniform. In other words, in the example of FIG. 10 , the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of light guides.

[0175] In the example of FIG. 10, polarization conversion is performed in the same manner as in the display device example 3 described above. That is, in the example of FIG. 10, reflective polarizing plate 49 may be configured to have the property of reflecting S-polarized light (transmitting P-polarized light). In this case, the reflective polarizing plate 49 transmits P-polarized light out of the light emitted from LED 201, which is the light source, and the transmitted light enters liquid crystal display panel 11. The reflective polarizing plate 49 reflects S-polarized light out of the light emitted from LED 201, which is the light source, and the reflected light passes through retardation plate 270 shown in FIG. 10. The light that passes through retardation plate 270 is reflected by reflector 271. The light reflected by reflector 271 passes through retardation plate 270 again and is converted to P-polarized light. The polarization-converted light passes through reflective polarizing plate 49 and enters liquid crystal display panel 11.

[0176] It should be noted that the λ / 4 plate 270, which is the retarder in FIG. 10, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270. In the configuration of FIG. 10, any retarder that changes the phase by 90° (λ / 2) when polarized light passes through it twice will suffice. The thickness of the retarder may be adjusted according to the distribution of incident angles of the polarized light. It should be noted that in FIG. 10 as well, the polarization design for polarization conversion may be configured in reverse (reversing the S-polarized light and P-polarized light) from the above explanation.

[0177] In a typical TV device, the light emitted from the LCD panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown by the X-axis in FIG. 12(a)) and the vertical direction of the screen (shown by the Y-axis in FIG. 12(b)). In contrast, the diffusion characteristics of the light beam emitted from the LCD panel 11 of this embodiment are 1 / 5 of the 62-degree viewing angle of a typical TV device, as shown in Example 1 of FIG. 12, when the viewing angle at which the luminance is 50% of that at a front view (angle of 0 degrees) is set to 13 degrees. Similarly, the vertical viewing angle is asymmetric between the top and bottom, and the reflection angle and the area of ​​the reflective surface of the reflective light guide are optimized to keep the upper viewing angle to about 1 / 3 of the lower viewing angle. As a result, the amount of image light directed toward the monitoring direction is significantly improved compared to conventional LCD TVs, with brightness being more than 50 times higher.

[0178] Furthermore, assuming the viewing angle characteristics shown in Example 2 in Figure 12, if the viewing angle at which brightness is 50% of that when viewed from the front (angle of 0 degrees) is set to 5 degrees, this will be 1 / 12 of the 62 degrees of devices used for general TV applications. Similarly, the vertical viewing angle is optimized by optimizing the reflection angle and the area of ​​the reflective surface of the reflective light guide so that the viewing angle is approximately 1 / 12 of that of devices used for general TV applications, with equal viewing angle both above and below. As a result, the amount of image light directed in the monitoring direction is significantly improved compared to conventional LCD TVs, and brightness is more than 100 times greater.

[0179] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux directed in the monitoring direction can be concentrated, significantly improving the efficiency of light utilization. As a result, even when using a liquid crystal display panel for general TV applications, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create a video display device that is compatible with information display systems facing bright outdoor environments.

[0180] When using a large LCD display panel, the overall brightness of the screen can be improved by directing the light from the periphery of the screen inward so that it is directed toward the observer when the observer is facing the center of the screen. Figure 11 shows the convergence angle between the long and short sides of the panel when the observer's distance from the panel, L, and the panel size (screen ratio 16:10) are used as parameters. When monitoring with the screen in portrait orientation, the convergence angle can be set to match the short side. For example, when using a 22-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.

[0181] Similarly, when monitoring with a 15-inch panel in portrait orientation, if the monitoring distance is 0.8 m, a convergence angle of 7 degrees will allow the image light from the four corners of the screen to be effectively directed towards the monitor. As mentioned above, depending on the size of the LCD panel and whether it is used portrait or landscape, the overall brightness of the screen can be improved by directing the image light from the periphery of the screen towards the monitor who is in the optimum position to monitor the centre of the screen.

[0182] As shown in Figure 9, the basic configuration involves a light source device directing a light beam with a narrow angle of directionality to a liquid crystal display panel 11, which is then luminance-modulated according to a video signal. The video information displayed on the screen of the liquid crystal display panel 11 is then reflected by a retroreflector, and the resulting floating image is displayed indoors or outdoors via a transparent member 100.

[0183] 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 (air floating image display device) with higher light utilization efficiency.

[0184] In this way, the configuration of the space-floating image display device of FIGS. 4A to 4P can realize a convenient and suitable space-floating image display device using an optical system that includes at least a retroreflector, which is a retroreflecting member.

[0185] This space-floating image display device includes a display device 1. The display device 1 includes a liquid crystal display panel 11 and a light source device 13. When the space-floating image display device is continuously used, the light source device 13 generates heat as it emits image light, causing the temperature inside the housing of the space-floating image display device to rise, making it necessary to exhaust the heat outside the space-floating image display device.

[0186] Fig. 13A is a side view showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of Fig. 13A has the configuration of the space-floating image display device 1000 of Fig. 4A. The space-floating image display device 1000 shown in Fig. 13A is equipped with an optical system 2 corresponding to the optical system of Fig. 2A. The space-floating image display device 1000 shown in Fig. 13A is installed horizontally so that the surface on which the space-floating image 3, which will be the floating image in the air, is formed faces upward, and a transparent member 100 is installed on the upper surface side of the housing of the space-floating image display device 1000.

[0187] Then, the image light emitted from the display device 1 travels through the retroreflector 2 and the polarization separation member 101 toward the transparent member 100. The image light that has passed through the transparent member 100 travels diagonally upward toward the user 230, forming the space-floating image 3. That is, the space-floating image 3 is formed above the space-floating image display device 1000, that is, in the z-axis direction.

[0188] Furthermore, the aerial operation detection sensor 1351 is installed on the user 230 side at the upper side inside the housing 1190 of the space-floating image display device 1000. The aerial operation detection sensor 1351 can perform user operation of the space-floating image 3 by detecting the position of an operation object such as the finger of the user 230 that is present near the space-floating image 3 above the space-floating image display device 1000.

[0189] In this way, the aerial operation detection sensor 1351 and the space floating image 3 are installed or formed above the display device 1, that is, in the z-axis direction. In the space floating image display device 1000, the light source device 13 of the display device 1 generates heat.

[0190] Then, the temperature inside the housing of the space-floating image display device rises, creating an updraft as shown by the dotted arrow A, and since the pressure outside the space-floating image display device is more negative than inside the housing, air flows from inside the housing of the space-floating image display device to the outside of the space-floating image display device, dissipating heat. At this time, the aerial operation detection sensor 1351 deteriorates due to heat transfer to the aerial operation detection sensor 1351, and the detection accuracy deteriorates, making accurate detection difficult.

[0191] Furthermore, when the airborne operation detection sensor 1351 transfers heat to the outside of the space floating image display device, the space floating image 3 above it fluctuates, making it difficult to accurately detect the position of the user's 230 finger, and preventing good operation using the space floating image 3. Therefore, it is necessary to properly exhaust heat to the outside of the space floating image display device.

[0192] FIG. 13B is a side view showing an example of the configuration of a space-floating image display device. FIG. 13B shows the configuration of FIG. 13A with a heat exhaust duct 131. As shown in FIG. 15, the duct 131 has an intake opening 132 for receiving exhaust heat above the heat-generating display device 1, with a gap between them to prevent direct conduction to the display device 1. The duct 131 is installed so as to at least overlap the display device 1 when viewed from above, that is, when the housing 1190 is viewed from the -z'-axis direction. Note that if the duct 131 is made of a material such as resin with a lower thermal conductivity than the case of the display device 1, the edge of the intake opening 132 may be in contact with and face the display device 1. Furthermore, the duct 131 has an exhaust opening 133 on the user's side above the housing of the space-floating image display device for emitting heat to the outside of the space-floating image display device in the direction of the dotted arrow A.

[0193] Duct 131 sends heat out through the inside of duct 131 from intake opening 132 to exhaust opening 133. Duct 131 is installed so as to avoid aerial operation detection sensor 1351 in the x direction (left-right direction), thereby suppressing heat transfer to aerial operation detection sensor 1351. Exhaust opening 133 is installed facing upward on the top surface of the housing of the space floating image display device. Heat is exhausted efficiently from the upper exhaust opening 133 even in the case of natural air cooling.

[0194] On the other hand, the exhaust opening 133 exhausts the exhaust heat toward between the floating image 3 and the user 230 so that the exhaust heat (hot air) from the exhaust opening 133 does not hit the floating image 3. That is, the user 230 stands in a position in the y direction (front-back direction) farther away from the front end of the housing of the floating image display device as seen from the user 230, and the exhaust heat (hot air) is not exhausted in a direction farther away from the front end as seen from the user 230.

[0195] Therefore, the heat exhaust from the exhaust opening 133 is exhausted by restricting the direction of the opening edge toward the space between the floating image 3 and the front end of the housing of the floating image display device as seen from the user 230. This suppresses fluctuations in the floating image 3 (changes in refractive index due to temperature changes), allowing the aerial operation detection sensor 1351 to perform accurate detection. In addition, because heat is not exhausted toward the user 230, consideration is given to the user's biological health (avoiding dry skin, rough skin, etc.).

[0196] Furthermore, fluctuations in the floating-in-space image 3 also occur when heat is released between the floating-in-space image 3 and the transparent member 100. The image light that passes through the transparent member 100 travels diagonally upwards towards the user 230, forming the floating-in-space image 3. The released heat then avoids the image light that passes through the transparent member 100 and the floating-in-space image 3 that it forms, and is released towards the space between the floating-in-space image 3 and the user 230, thereby further suppressing fluctuations in the floating-in-space image 3 and allowing the aerial operation detection sensor 1351 to perform accurate detection.

[0197] Fig. 14 is a perspective view showing an example of the configuration of a space-floating image display device. Fig. 14(1) is an external perspective view of the space-floating image display device of Fig. 13B. Fig. 14(2) is an internal perspective view of the space-floating image display device of Fig. 13B. Fig. 15 is a front view of the display device 1 of the space-floating image display device of Fig. 13B.

[0198] The projection port 102 for the floating image 3 on the top surface of the housing 1190 of the floating image display device of Figures 14(1) and 14(2) is covered with a rectangular transparent member 100 made of glass or the like and a polarization separation member 101 installed on the underside of the transparent member 100.

[0199] The transparent member 100 covers the detection opening 104 of the aerial operation detection sensor 1351 provided on the top surface of the housing 1190. The transparent member 100 also has an opening as a discharge opening so as not to cover the discharge opening 133 of the duct 131, and is used for alignment with the discharge opening 133. The transparent member 100 may have a small shape that avoids the discharge opening 133.

[0200] Inside the housing 1190, the retroreflector 2 and the λ / 4 plate 21 provided on the incident surface of the retroreflector 2 are installed on the rear side in the y direction (front-to-back direction) as viewed from the user 230, that is, on the far side. The mid-air operation detection sensor 1351 is installed on the front side in the y direction (front-to-back direction) as viewed from the user 230, that is, on the near side.

[0201] 15, the exhaust openings 133 of the duct 131 are arranged on both sides of the aerial operation detection sensor in the x direction (left-right direction) so as to avoid the aerial operation detection sensor 1351. In other words, the distance between the two exhaust openings 133 of the duct 131 is longer than the length of the aerial operation detection sensor 1351 in the x direction (left-right direction). Note that the length of the aerial operation detection sensor 1351 in the x direction (left-right direction) is the same as or longer than the length of the display device 1 in the x direction (left-right direction).

[0202] As shown in Fig. 14(2), the duct 131 has a duct path that slopes upward from the rear to the front in the y direction (front-rear direction) when viewed from the user 230, that is, from the back to the front. The intake opening 132 of the duct 131 is a rectangular opening having a diameter in the x direction (left-right direction) that is the same as or longer than the outer dimensions of the opposing display device 1. Alternatively, the intake opening 132 is a rectangular opening having a diameter that is at least the same as or longer than the row length (see Fig. 5) of the plurality of row-shaped LED elements 201 that constitute the light source device 13 in the opposing display device 1.

[0203] Intake opening 132 may be trapezoidal or elliptical in shape, in addition to rectangular. LED element 201 in display device 1 is preferably installed on the upper side of display device 1 close to the intake opening of duct 131, i.e., in the z'-axis direction, but may also be installed on the lower side of display device 1, i.e., in the -z'-axis direction.

[0204] The duct path from the intake opening 132 has a shape that is the same as the diameter of the intake opening 132 and is inclined upward. This upward inclination is parallel to or flush with the outer surface (the inclined surface in the vertical direction or the side surface in the horizontal direction) of the case, such as a plastic case, in which the light source device 13 is housed. The duct 131 can be attached and fixed to the plastic case of the display device 1 with a plate-shaped joint member. The duct 131 may also be attached and fixed by inserting the plastic case of the display device 1 into the intake opening 132.

[0205] Heat taken in through the intake opening 132 is separated by the Y-shaped, bifurcated separation section 134 of the duct 131. The separation section 134 on the inner surface of the duct is ridge-shaped in the direction in which the exhaust heat travels, and the exhaust heat is separated from the central ridge separation section 134 toward both ends in the x direction (left-right direction). Both ends of the duct 131 each have an exhaust opening 133 facing upward. In other words, the duct 131 is inclined upward from the center to both ends. The duct 131 has the exhaust opening 133 facing upward to exhaust heat.

[0206] Here, as shown in Figure 14 (2), the duct 131 has vertical surfaces 135 at both ends on the front side in the y direction (front-back direction), that is, on the user 230 side, to shorten the duct 131. This allows the space floating image display device to be made smaller in size in the y direction (front-back direction). Note that the exhaust opening 133 of the duct 131 is rectangular, but it may not be rectangular, and may be triangular, circular, or elliptical.

[0207] Figure 16 is a diagram showing an example of the configuration of the discharge opening 133 of the space floating image display device. Figure 16(1) is a cross-sectional view, and Figure 16(2) is a top view of the vicinity of the discharge opening 133. Figure 16(1) shows a cross-sectional view of the discharge opening 133 on the right side in the x direction (left-right direction) of the space floating image display device of Figure 16(2). In Figure 16(1), the front side in the y direction (front-back direction) is the side where the user stands (the right side of the drawing).

[0208] 16(1) is provided with fixed louvers 136 that change the direction of heat discharged into the duct path of exhaust opening 133 toward the rear (image side) in the y direction (front-to-back direction) of dotted arrow A. Louvers 136 are made up of slats that are narrower than exhaust opening 133 and are arranged diagonally, and can change the direction of heat discharged toward the surface of the slats.

[0209] 16(2) has two discharge openings 133 like the one in FIG. 16(1), with an aerial operation detection sensor 1351 installed between the two discharge openings 133. The range in the x direction (left and right direction) that can be detected by the aerial operation detection sensor 1351 is approximately equal to the range in the x direction (left and right direction) of the polarization separator 101. For this reason, if a gap is provided between the discharge openings 133 and the polarization separator 101 and the exhaust heat from the discharge openings 133 is not directed toward the polarization separator 101, it will not affect the floating image 3 formed above the polarization separator 101.

[0210] On the other hand, in Figure 16(1), the direction of the exhaust heat is set between 90 degrees vertically on the yz plane and 180 degrees toward the back. If it is below 90 degrees, there is a high possibility that the exhaust heat will be directed toward the user at the front end of the y direction (front-back direction) of the space floating image display device, which is not preferable.

[0211] 16(2), for example, the direction of heat exhaust from the exhaust opening 133 on the right side in the x direction (left-right direction) is set to 180 degrees, which is from 90 degrees (right side in the left-right direction) in the xy plane toward the back. If it is less than 90 degrees, there is a high possibility that the exhaust heat will be directed toward the user at the front end of the space floating image display device in the y direction (front-back direction), which is not preferable. Also, the exhaust opening 133 on the left side in the x direction (left-right direction) is symmetrical to the exhaust opening 133 on the right side.

[0212] In this way, it is preferable to reliably avoid heat exhaust from flowing between the transparent member 100 and the floating image 3, to the floating image 3, and to the user 230, depending on the direction of the exhaust heat. For this reason, the angle of the louver 136 in FIG. 16(1) is preferably 90 to 180 degrees, and more preferably 135 degrees. The direction of heat exhaust toward the center in the x direction (left and right direction) in FIG. 16(2) is restricted by making the edge of the exhaust opening in the x direction (left and right direction) a vertical surface. The louver 136 may be movable so that the direction of heat exhaust can be changed.

[0213] In addition to the function of changing the direction of exhaust heat, the louvers 136 can also prevent stray light (leakage light) from being seen by the user when light is scattered or reflected inside the duct 131 and emitted outside the spatial floating image display device 1000.

[0214] FIG. 17 is a diagram showing an example of the configuration of the discharge opening 133 of the space floating image display device. FIG. 17(1) is a cross-sectional view, and FIG. 17(2) is a top view of the vicinity of the discharge opening 133. FIG. 17(1) shows a cross-sectional view of the discharge opening 133 on the right side in the x direction (left-right direction) of the space floating image display device of FIG. 17(2). In FIG. 17(1), the left side in the x direction (left-right direction) is the side where the space floating image 3 is formed (the left side of the drawing). In FIG. 17, the two discharge openings 133 of FIG. 16 are rotated by 90 degrees.

[0215] In Fig. 17(1), a fixed louver 136 is provided in the duct path of the exhaust opening 133 to change the direction of exhaust heat to the x direction (left-right direction) of the dotted arrow A. In Fig. 17(2), the exhaust opening 133 of Fig. 17(1) is provided on the right side in the x direction (left-right direction), and a symmetrical exhaust opening 133 is provided on the left side in the x direction (left-right direction).

[0216] An aerial operation detection sensor 1351 is installed between the two discharge openings 133. The range in the x direction (left and right direction) that can be detected by the aerial operation detection sensor 1351 is approximately equal to the range in the x direction (left and right direction) of the polarization separator member 101. For this reason, if a gap is provided between the discharge openings 133 and the polarization separator member 101 and the exhaust heat from the discharge openings 133 is not directed toward the polarization separator member 101, it will not affect the floating image 3 formed above the polarization separator member 101.

[0217] On the other hand, in Fig. 17(1), the direction of the exhaust heat is set between 90 degrees vertically and 180 degrees to the right in the xz plane. If it is below 90 degrees, there is a high possibility that the exhaust heat will be directed towards the space floating image 3 at the center of the x direction (left and right direction) of the space floating image display device, which is not preferable.

[0218] In Fig. 17(2), for example, the direction of heat exhaust from the exhaust opening 133 on the right side in the x direction (left-right direction) is set to 180 degrees from 90 degrees (right side in the left-right direction) in the xy plane toward the back. If it is less than 90 degrees, there is a high possibility that the exhaust heat will be directed toward the user at the front end of the space floating image display device 1000 in the y direction (front-back direction), which is not preferable. In addition, the exhaust opening 133 on the left side in the x direction (left-right direction) is shaped symmetrically to the exhaust opening 133 on the right side.

[0219] In this way, it is preferable to reliably avoid heat dissipation between the transparent member 100 and the floating image 3, the floating image 3, and the user 230, depending on the direction of heat dissipation. For this reason, the angle of the louver 136 in FIG. 17(1) is preferably 90 to 180 degrees, and more preferably 135 degrees. The direction of heat dissipation toward the center in the x direction (left-right direction) in FIG. 17(2) is regulated by arranging the edge of the exhaust opening 133 in the x direction (left-right direction) in the same direction as the louver or vertically. Furthermore, heat dissipation toward the front and rear in the y direction (front-back direction) in FIG. 17(2) is regulated by arranging the edge of the exhaust opening in the y direction (front-back direction) vertically.

[0220] Therefore, the exhaust openings 133 on the top surface allow the floating images 3 to avoid the exhaust heat from the exhaust openings 133, forming an air curtain around the floating images 3 and avoiding dust and dirt floating in the air, thereby realizing a more suitable floating image display device 1000. Furthermore, the exhaust heat from the two exhaust openings 133 allows the user to recognize that the floating images 3 are between the air currents of the exhaust heat from the exhaust openings 133, thereby realizing a more suitable floating image display device 1000.

[0221] Fig. 18 is a diagram showing an example of the configuration of exhaust opening 133 of a space floating image display device. Fig. 18(1) shows a cross-sectional view of exhaust opening 133, and Fig. 18(2) is a top view of the vicinity of exhaust opening 133. Fig. 18 shows a modified symmetrical mechanism that changes the direction of heat exhausted from louvers 136 of two exhaust openings 133 that exhaust heat in Fig. 17. The symmetrical mechanism makes each of the opposing edges of the exhaust opening into stepped surfaces and edges 137 and stepped surfaces and edges 138, and makes the edges face each other with a gap between them, and exhausts heat from the gap as shown by dotted arrow A.

[0222] In Figure 18(1), exhaust heat from the duct path is discharged to the outside of the space floating image display device 1000 through a gap extending horizontally from the duct 131, which is closed at the top. That is, the exhaust heat flows from this horizontal gap toward the upward exhaust opening 133 and is discharged to the outside. At this time, the upward direction of the exhaust heat is determined by the inclined shape of the upward exhaust opening edges 137, 138. Therefore, the inclined surface shape of the upward edge edges 137, 138 in Figure 18 performs the same function as the inclination of the louver 136 in Figure 17. Therefore, the inclined shape of the edges 137, 138 determines the exhaust direction of the exhaust heat.

[0223] Fig. 19 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. 19(1) differs from the space-floating image display device 1000 of Fig. 13B in the position of the discharge opening 133. Also, Fig. 19(2) is a diagram showing a front view of the display device 1 of the space-floating image display device. Fig. 20 is a perspective view showing an example of the configuration of a space-floating image display device. Fig. 20(1) is an external perspective view of the space-floating image display device of Fig. 19(1). Fig. 20(2) is an internal perspective view of the space-floating image display device of Fig. 19(1).

[0224] 19(1) is provided with a duct 131 for exhausting heat. The duct 131 has an intake opening 132 for receiving exhaust heat facing the display device 1 above, i.e., in the z'-axis direction, towards the display device 1. The duct 131 also has an exhaust opening 133 for discharging the exhaust heat to the outside of the space-floating image display device, which is provided on the user side on the side in the x-direction (left-right direction) of the space-floating image display device.

[0225] The duct 131 sends the exhaust heat to the outside through the inside of the duct 131 from the intake opening 132 to the exhaust opening 133 as shown by the dotted arrow A in Figure 19 (2). The duct 131 is installed so as to avoid the aerial operation detection sensor 1351 in the x direction (left and right direction), thereby suppressing heat transfer to the aerial operation detection sensor 1351.

[0226] The exhaust opening 133 is installed on the side of the floating-in-space image display device 1000, facing in the x direction (left-right direction). By providing the exhaust opening 133 on the side, the exhaust heat (exhaust hot air) from the exhaust opening 133 is not directed towards the floating-in-space image 3 or the space between the floating-in-space image 3 and the transparent member 100. This reduces fluctuations in the floating-in-space image 3 (changes in refractive index due to temperature changes), allowing the aerial operation detection sensor 1351 to perform accurate detection. Furthermore, because the exhaust heat from the exhaust opening is not directed towards the user 230, consideration is given to the user's biological health (avoiding dry skin, rough skin, etc.).

[0227] The projection port 102 for the space-floating image 3 on the top surface of the housing 1190 of the space-floating image display device of Figures 20(1) and 20(2) is covered by a flat, rectangular transparent member 100 made of glass or the like, and a polarization separation member 101 installed on the underside of the transparent member 100. The transparent member 100 is flat, rectangular, and covers the detection port 104 of the mid-air operation detection sensor 1351 installed on the top surface of the housing 1190. The discharge opening 133 of the duct 131 is installed on the side. The transparent member 100 is flat, rectangular, which is easy to process, and can achieve low costs.

[0228] 19(2), the exhaust openings 133 of the duct 131 are arranged on each side of the space floating image display device on both sides in the x direction (left and right direction) so as to avoid the mid-air operation detection sensors 1351.

[0229] Duct 131 has a duct path that slopes upward from the rear to the front in the y direction (front-rear direction) when viewed from user 230, that is, from the back to the front. Intake opening 132 of duct 131 faces display device 1, and exhaust heat taken in through intake opening 132 is separated by the Y-shaped bifurcated path of duct 131. The exhaust heat flows toward both ends of duct 131 and is exhausted from exhaust openings 133 on the side surfaces.

[0230] In this way, the path from the forked path to the exhaust opening 133 on the side becomes a linear path in one direction, the x direction (left and right direction), and it is possible to prevent the exhaust heat from staying and stagnating within the duct path. In other words, it is possible to suppress the exhaust heat from being transferred to the aerial operation detection sensor 1351.

[0231] Furthermore, exhaust opening 133 of duct 131 has a rectangular shape with an upper vertex at the center of the opening width of exhaust opening 133, and exhaust heat in the duct path is gathered near the upper vertex and discharged from exhaust opening 133. Although exhaust opening 133 of duct 131 is rectangular, it may not be rectangular, but may be triangular, circular, or elliptical.

[0232] Fig. 21 is a diagram showing an example of the configuration of a space-floating image display device. Fig. 21 shows the space-floating image display device of Fig. 19 equipped with a louver 136. The space-floating image display device of Fig. 21(1) is provided with a duct 131 for exhausting heat. The duct 131 has an exhaust opening 133 for discharging exhaust heat to the outside of the space-floating image display device, which is provided on the user side on the side of the x-direction (left-right direction) of the space-floating image display device 1000. As shown in Fig. 21(2), the duct 131 is installed so as to avoid the aerial operation detection sensor 1351 in the x-direction (left-right direction), thereby suppressing heat transfer to the aerial operation detection sensor 1351.

[0233] The exhaust opening 133 is installed on the side of the floating image display device, facing the x direction (left and right direction). The exhaust opening 133 in Fig. 21(1) is equipped with a fixed louver 136 that changes the direction of exhaust heat. The heat exhausted from the exhaust opening 133 is changed by the louver 136 to a combined direction of the x direction (left and right direction), y direction (front and back direction), and z direction (up and down direction).

[0234] That is, the heat discharged from the exhaust openings on the side surfaces is discharged at an upward incline while spreading rearward in the y direction (front-to-back direction). Furthermore, the side surfaces on which the exhaust openings 133 are provided prevent the exhaust heat from heading toward the transparent member 100 and the floating images 3 located in the center in the x direction (left-to-right direction). In this way, the exhaust heat can be prevented from being discharged between the transparent member 100 and the floating images 3, toward the floating images 3, and toward the user 230.

[0235] Fig. 22 is a diagram showing an example of the configuration of a space-floating image display device. Fig. 22 shows the space-floating image display device of Fig. 21 with the position of the louver changed. The space-floating image display device of Fig. 22(1) is provided with a duct 131 for exhausting heat. The duct 131 has an exhaust opening 133 for emitting heat to the outside of the space-floating image display device, which is provided on the user side on the side in the x direction (left and right direction) of the space-floating image display device.

[0236] As shown in Fig. 22(2), the duct 131 is installed in the x direction (left-right direction) to avoid the aerial operation detection sensor 1351, thereby suppressing heat transfer to the aerial operation detection sensor 1351. The exhaust opening 133 is installed on the side of the space floating image display device, facing the x direction (left-right direction).

[0237] The exhaust opening 133 in Fig. 22(1) is provided with fixed louvers 136 that change the direction of exhaust heat. The heat exhausted from the exhaust opening 133 is changed by the louvers 136 to a composite direction of the x direction (left-right direction), y direction (front-back direction), and z direction (up-down direction). In other words, the heat exhausted from the exhaust opening 133 on the side is exhausted in the y direction (front-back direction) while spreading outward to the front and tilting upward.

[0238] Furthermore, the side surface on which the exhaust opening is provided prevents exhaust heat from heading toward the transparent member 100 and the space floating image 3 located at the center in the x direction (left and right direction), and furthermore, from heading toward the user 230 who is within the width of the space floating image display device in the x direction (left and right direction). In this way, exhaust heat can be prevented from being discharged between the transparent member 100 and the space floating image 3, toward the space floating image 3, and toward the user 230.

[0239] Figure 23 shows an example of the configuration of a space floating image display device. Figure 23(1) shows the configuration of Figure 13B with an intake fan 139, an exhaust fan 140, etc. Figure 23(2) shows the configuration of Figure 19(1) with an intake fan 139, an exhaust fan 140, etc.

[0240] 23(1) and 23(2), the duct 131 has an intake opening 132 for receiving exhaust heat above the display device 1, facing the display device 1. The duct 131 has an exhaust opening 133 for discharging the heat to the outside of the space floating image display device.

[0241] Intake duct 141 draws air from outside the housing of the space-floating image display device into the housing from intake port 142 on the side surface at the front of the space-floating image display device in the y direction (front-rear direction) when viewed from user 230. Intake duct 141 is provided with discharge port 143 for discharging the drawn air from below toward intake opening 132 of duct 131 or into duct 131.

[0242] The intake port 142 of the intake duct 141 may be located on the rear side (back) in the y direction (front-rear direction) as viewed from the user 230, or on a side surface in the x direction (left-right direction). The discharge port 143 of the intake duct 141 may be located opposite the display device 1 via a gap or in contact therewith to discharge air from below. The intake duct 141 may be formed integrally with the duct 131.

[0243] Duct 131 is provided with exhaust fan 140 that forcibly exhausts (forced air cooling) air (exhaust) within the duct path of duct 131. Exhaust fan 140 may be located near exhaust opening 133 of duct 131 or midway along the duct path closer to intake opening 132 than exhaust opening 133. By using exhaust fan 140, the space-floating image display device can discharge heat to the outside of the space-floating image display device more quickly than natural air cooling when exhaust fan 140 is not operated or installed, thereby lowering the temperature inside the space-floating image display device.

[0244] The intake duct 141 is provided with an intake fan 139 that forcibly draws in air (forced air cooling) within the duct path of the intake duct 141. The intake fan 139 may be located near the intake port 142 of the intake duct 141 or midway along the duct path closer to the discharge port 143 than the intake port 142. By using the intake fan 139, the space-floating image display device can discharge heat outside the space-floating image display device more quickly than natural air cooling when the intake fan 139 is not operating or installed, thereby lowering the temperature inside the space-floating image display device. Note that the intake fan 139 can lower the temperature inside the space-floating image display device even if the exhaust fan 140 is not operating or installed.

[0245] Furthermore, temperature sensor 144, which measures the ambient temperature near aerial operation detection sensor 1351, is installed on aerial operation detection sensor 1351 or near aerial operation detection sensor 1351 inside the space-floating image display device. Furthermore, LED temperature sensor 145, such as an LED thermistor, is installed on LED board 202 (see FIG. 9) of display device 1. Exhaust fan 140 or intake fan 139, or both fans, are controlled by temperature sensor 144 or LED temperature sensor 145, or both temperature sensors. Note that LED temperature sensor 145 may be a driving PCB thermistor or the like, as long as it can detect the temperature inside the space-floating image display device.

[0246] For example, when forming the floating-in-space image 3, the temperature sensor 144 near the aerial operation detection sensor 1351 and the LED temperature sensor 145 inside the floating-in-space image display device detect the temperature. If this temperature is equal to or higher than a predetermined first temperature (for example, a temperature 10 degrees lower than the heat resistance temperature of heat-deteriorating parts such as the aerial operation detection sensor 1351), the exhaust fan 140 or the intake fan 139 operates to lower the temperature inside the floating-in-space image display device. Also, if the temperature is equal to or higher than a predetermined second temperature (for example, a temperature 5 degrees lower than the heat resistance temperature of heat-deteriorating parts such as the aerial operation detection sensor 1351), both the exhaust fan 140 and the intake fan 139 operate to quickly lower the temperature inside the floating-in-space image display device. Note that the operation of the exhaust fan 140 or the intake fan 139 may be performed based on the temperature difference between the detected temperatures.

[0247] By operating the exhaust fan 140, the exhaust heat inside the space-floating image display device is forcibly exhausted. As a result, the pressure inside the space-floating image display device becomes negative compared to the outside of the space-floating image display device. Then, air flows into the space-floating image display device from the intake port 142 of the intake duct 141, and an airflow is generated from the intake port 142 to the exhaust opening 133, so that heat is continuously exhausted, and the temperature inside the space-floating image display device drops even if the intake fan 139 is not operating.

[0248] On the other hand, by operating the intake fan 139, the inside of the space-floating image display device becomes a positive pressure. Therefore, the outside of the space-floating image display device (outside the exhaust opening) becomes a negative pressure relative to the inside of the space-floating image display device. Then, the space-floating image display device exhausts air (exhaust heat) from the exhaust opening 133, an airflow is generated from the intake port 142 to the exhaust opening 133, and heat is continuously exhausted, so the temperature inside the space-floating image display device drops even if the exhaust fan 140 is not operating.

[0249] By operating both the exhaust fan 140 and the intake fan 139, the temperature inside the space floating image display device drops faster than when only one fan is operating. When the exhaust fan 140 and the intake fan 139 are operating simultaneously, the temperature of the space floating image display device drops most quickly because a more immediate fan airflow is generated than airflow caused by positive and negative pressures (wind pressure) inside and outside the space floating image display device.

[0250] When the exhaust fan 140 operates first for a while, and then the intake fan 139 operates, the space floating image display uses positive and negative pressure (wind pressure) to exhaust air, just like when only the exhaust fan 140 operates. When both operate, the space floating image display generates a fan airflow and lowers the temperature. Therefore, in this case, the temperature of the space floating image display drops more quickly than when only the exhaust fan 140 operates.

[0251] When the intake fan 139 operates first for a while, and then the exhaust fan 140 operates, the space floating image display uses positive and negative pressure (wind pressure) to exhaust air, just like when only the intake fan 139 operates. When both operate, the space floating image display generates a fan airflow and lowers the temperature. Therefore, in this case, the temperature of the space floating image display drops more quickly than when only the intake fan 139 operates.

[0252] The exhaust fan 140 and the intake fan 139 are operated from a predetermined first temperature and a predetermined second temperature. This operation may be performed by increasing the threshold of the predetermined temperature. This operation may also be performed by detecting the temperature while the fans are operating, and by using a single fan and a multiple fan operation in combination. Therefore, the space floating image display device can obtain a more stable temperature inside the space floating image display device, and the temperature of the exhaust heat emitted will also be stable.

[0253] The heat (heated air) exhausted from the stable exhaust opening 133 suppresses fluctuations in the floating image 3 (changes in refractive index due to temperature changes), enabling accurate detection by the aerial operation detection sensor 1351. Furthermore, the heat exhausted from the exhaust opening 133 is exhausted with little temperature change and causes little discomfort even when the user 230 touches it.

[0254] As described above, the technology according to this embodiment has been described using the space-floating image display device of Fig. 4A using the optical system of Fig. 2A as an example. These technologies can be applied to the space-floating image display devices of Fig. 4A to Fig. 4P using the optical systems of Fig. 2A to Fig. 2D.

[0255] The technology according to this embodiment displays high-resolution, high-brightness video information in a state where it floats in space, 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 makes it possible to provide a contactless user interface that can be used without anxiety. This contributes to the "Good Health and Well-Being" goal, one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0256] Furthermore, the technology of this embodiment reduces the divergence angle of the emitted image light and aligns it with a specific polarization, thereby efficiently reflecting only the normal reflected light from the retroreflector, thereby enabling high light utilization efficiency and producing bright and clear floating images in space.The technology of this embodiment can provide a highly usable non-contact user interface that can significantly reduce power consumption.This contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote technological innovation and infrastructure" and "Make cities and human settlements sustainable."

[0257] Although various embodiments have been described above in detail, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system to clearly explain the present invention, and the present invention is not necessarily limited to a system including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0258] 1:Display device, 2: Retroreflective plate (retroreflective plate), 3: Spatial image (floating image in space), 11: LCD panel, 12: Absorptive polarizer, 13: Light source device, 54: Light redirection panel, 100: transparent material, 101: Polarization separation member, 101B: Polarization separation member, 102: Projection port, 103: heat sink, 104: detection port, 105: Window glass, 202: LED board, 131: Duct, 132: Intake opening, 133: Discharge opening; 134: Separation part, 135: Vertical plane, 136: Luba, 137, 138: Edge, 139: Intake fan, 140: Exhaust fan, 141: Intake duct, 142: Intake port, 143: Outlet, 144: temperature sensor, 145: LED temperature sensor, 151: Retroreflective plate, 203: Light guide, 205, 271: Reflective sheeting, 206, 270: Retardation plate, 230: User, 1000: Space floating image display device, 1102: video display unit, 1110: control unit, 1160: Video control unit, 1180: Imaging unit, 1190: Housing, 1350: mid-air operation detection unit, 1351: Air operation detection sensor.

Claims

1. a display device provided within the housing and emitting image light; an optical system that forms a floating image that floats in the air outside the housing from the image light; an aerial operation detection sensor that detects the operation object of the floating-in-the-air image; a duct for discharging heat generated by the display device, The heat discharged from the duct is discharged while avoiding the floating image. A floating video display device.

2. 2. The airborne image display device according to claim 1, The duct has an exhaust opening on the top surface of the housing for exhausting heat.

3. 2. The airborne image display device according to claim 1, The duct has an exhaust opening on a side surface of the housing for exhausting heat.

4. 2. The airborne image display device according to claim 1, The duct has an intake opening for receiving exhaust heat from the display device.

5. 5. The airborne image display device according to claim 4, The airborne image display device, wherein the suction opening has a diameter equal to or longer than that of the display device.

6. 2. The airborne image display device according to claim 1, The duct has exhaust openings for exhausting heat at both left and right ends of the housing, respectively.

7. 7. The airborne image display device according to claim 6, A floating-in-the-air image display device, wherein the distance between each of the discharge openings is longer than the length of the aerial operation detection sensor.

8. 2. The airborne image display device according to claim 1, The duct has an upwardly inclined duct path.

9. 2. The airborne image display device according to claim 1, The duct is provided with a louver that changes the direction of exhaust heat to an exhaust opening through which heat is exhausted.

10. 2. The airborne image display device according to claim 1, The duct is provided with a spigot mechanism that changes the direction of exhaust heat at the exhaust opening through which heat is exhausted.

11. 2. The airborne image display device according to claim 1, The duct is equipped with an exhaust fan that forcibly exhausts heat.

12. 12. The airborne image display device according to claim 11, an intake duct that draws air from outside the housing into the housing; The air-floating image display device, wherein the intake duct is equipped with an intake fan that forcibly draws in air.

13. 2. The airborne image display device according to claim 1, The air-floating image display device, wherein the heat discharged from the duct is discharged toward a space between the air-floating image and the front end of the housing.

14. 2. The airborne image display device according to claim 1, a transparent member that transmits image light from the optical system; The air-floating image display device, wherein the heat discharged from the duct is discharged while avoiding the image light passing through the transparent member and the air-floating image.

Images