Aerial image display device

Abstract

To provide a technique that can display aerial floating images more suitably, and specifically, contributes to Sustainable Development Goals, "3: Good Health and Well-Being", "9: Industry, Innovation and Infrastructure", and "11: Sustainable Cities and Communities".SOLUTION: An aerial image display apparatus includes: a display unit for displaying an image; and an optical system for retro-reflecting image light emitted from the display unit. The optical system retro-reflects light and the light forms an aerial floating image. The display unit is formed in a nonplanar shape so that the aerial floating image is also formed in a nonplanar shape.SELECTED DRAWING: Figure 17A

Description

[Technical Field]

[0001] The present disclosure relates to a technology for a floating image display device. [Background technology]

[0002] As an example of a space-floating image display device, an image display device and a display method that directly displays an image as a spatial image toward the outside are already known. Also, a detection system that reduces false detections of operations on the operation surface of the displayed spatial image is described, for example, in JP 2019-128722 A (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 space floating image display device of Patent Document 1 does not fully consider the technology for displaying the space floating image more suitably under various conditions of use.

[0005] An object of the present invention is to provide a technique that can more suitably display a floating-in-space image. [Means for solving the problem]

[0006] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above problems, but to cite one example, a floating-in-the-air image display device that displays a floating-in-the-air image includes at least a display unit that displays the image and an optical system that retroreflects image light emitted from the display unit, and the reflected light retroreflected by the optical system forms the floating-in-the-air image, and the floating-in-the-air image is formed in a non-planar shape by making the display unit non-planar. [Effects of the Invention]

[0007] According to the representative embodiments of the present invention, a more suitable floating-in-the-air image display device can be realized. The above-mentioned problems and other problems, as well as the configurations for solving these problems and the effects thereof, will be made 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; [Figure 2A] 1 is a diagram showing a V-shaped configuration as an example of a main part configuration of a space floating image display device according to an embodiment. [Figure 2B] 10A and 10B are diagrams illustrating an example of a detailed structure of a retroreflective member. [Figure 3] 1 is a diagram showing a Z-type configuration as an example of a main part configuration of a space floating image display device according to an embodiment. FIG. [Figure 4A] 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 4B] 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 4C] 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 4D] 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 4E] 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 4F] 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 5] FIG. 1 is a characteristic diagram showing the relationship between the surface roughness of a retroreflective member and the amount of blur of a retroreflected image (a spatially floating image). [Figure 6] 1 is a diagram illustrating an example of the configuration of a video display device according to an embodiment; [Figure 7] FIG. 1 is a diagram showing an example of a V-type configuration of a space floating image display device according to an embodiment (first embodiment). [Figure 8] FIG. 10 is a diagram showing another example of a V-type configuration of the space floating image display device according to one embodiment (second embodiment). [Figure 9] FIG. 10 is a diagram showing another example of a V-type configuration of the space floating image display device according to an embodiment (third embodiment). [Figure 10] FIG. 10 is a block diagram showing an example of the internal configuration of a space floating image display device according to an embodiment (fourth embodiment). [Figure 11] FIG. 10 is a diagram showing an example of a Z-type configuration of a space floating image display device according to an embodiment (fifth embodiment). [Figure 12] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (sixth embodiment). [Figure 13] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to one embodiment (seventh embodiment). [Figure 14] FIG. 13 is a diagram showing an example of the shape of a polarization separation member in a space floating image display device according to an embodiment (eighth embodiment). [Figure 15A] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 15B] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 15C]FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 15D] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 15E] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 15F] FIG. 13 is a diagram showing another example of a Z-type configuration of the space floating image display device according to an embodiment (eighth embodiment). [Figure 16] FIG. 13 is a diagram showing an example of the shape of a display unit of an image display device, which is a space floating image display device according to one embodiment (ninth embodiment). [Figure 17A] FIG. 13 is a diagram showing another example of the configuration of the space floating image display device according to one embodiment (ninth embodiment). [Figure 17B] FIG. 13 is a diagram showing another example of the configuration of the space floating image display device according to one embodiment (ninth embodiment). [Figure 17C] FIG. 13 is a diagram showing another example of the configuration of the space floating image display device according to one embodiment (ninth embodiment). [Figure 17D] FIG. 13 is a diagram showing another example of the configuration of the space floating image display device according to one embodiment (ninth embodiment). [Figure 18A] FIG. 19 is a diagram showing another example of the configuration of the space floating image display device according to an embodiment (tenth embodiment). [Figure 18B] FIG. 13 is a diagram showing an example of the configuration of a mask in a space floating image display device according to an embodiment (tenth embodiment). [Figure 19A] FIG. 19 is a diagram showing another example of the configuration of the space floating image display device according to an embodiment (eleventh embodiment). [Figure 19B] FIG. 16 is a block diagram showing an example of the internal configuration of a space floating image display device according to an embodiment (eleventh embodiment). DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical components are generally designated by the same reference numerals, and repeated description will be omitted. In the drawings, the actual position, size, shape, and scope of each component may not be depicted to facilitate understanding of the invention. For the purpose of explanation, when describing program-based processing, the program, functions, processing units, etc. may be described as the main focus. However, the main focus of these hardware components is a processor, or a controller, device, computer, system, etc., configured with the processor. A computer executes processing in accordance with a program loaded into memory using resources such as memory and communication interfaces as appropriate, thereby realizing predetermined functions, processing units, etc. The processor may be configured with semiconductor devices such as a CPU / MPU or GPU. The processor may be configured with devices or circuits capable of performing predetermined calculations. Processing is not limited to software program processing, but can also be implemented using dedicated circuits. Dedicated circuits such as FPGAs, ASICs, and CPLDs can be used. The program may be pre-installed on the target computer as data, or may be distributed as data from a program source to the target computer and installed. The program source may be a program distribution server on a communication network, or a non-transitory computer-readable storage medium such as a memory card or disk. The program may be composed of multiple modules. The computer system may be composed of multiple devices. The computer system may be composed of a client-server system, a cloud computing system, etc. Various data and information may be composed of structures such as, but not limited to, tables and lists. Expressions such as identification information, identifiers, IDs, names, and numbers are interchangeable.

[0010] <Embodiment> A space-floating image display device according to an embodiment includes an image display device, a beam splitter serving as a polarization separation member, and a retroreflective member having a λ / 4 plate (a phase difference plate, a quarter-wave plate) on its retroreflective surface. The image display device includes a light source device and a display panel or liquid crystal display panel serving as an image source (image display element) that emits image light of a specific polarization (e.g., P-polarized light). The light source device generates and supplies light as backlight to the liquid crystal display panel. A polarization separation member is disposed in the space connecting the liquid crystal display panel and the retroreflective member of the image display device. The polarization separation member transmits the image light of a specific polarization from the liquid crystal display panel toward the retroreflective member and reflects the image light of the other polarization (e.g., S-polarized light) after polarization conversion by the retroreflective member and the λ / 4 plate. The reflected image light of the other polarization generates and displays a space-floating image, which is a real image, at a predetermined position in a direction different from that of the image display device.

[0011] In order to improve the contrast performance of the spatially floating image, the image display device may be provided with a polarization conversion unit that aligns the light source light from the light source device to be polarized in a specific direction. For example, the light source device may include a point or planar light source, an optical element unit that reduces the divergence angle of the light from the light source, a polarization conversion unit (such as a polarization conversion element) that aligns the light from the light source to be polarized in a specific direction, and a light guide having a reflective surface that propagates the light from the light source to the liquid crystal display panel, and the image luminous flux of the image light from the liquid crystal display panel is controlled by the shape and surface roughness of the reflective surface of the light guide.

[0012] The floating image display device of the embodiment is configured to be used indoors, although not limited thereto, and is equipped with an image display device unit having a housing that can be placed on a desk, and a floating image display unit having a frame structure.

[0013] The video display device mainly comprises a liquid crystal display panel and a light source (backlight).

[0014] The space floating image display unit is configured to have an optical system made up of a polarization separation member, a retroreflective member, etc. The optical system of this embodiment has a structure supported by a frame made up of grooves, metal, resin, etc.

[0015] [Space-floating image display device] The following embodiments relate to a space-floating image display device that can display an image generated by image light from a large-area image light source as a space-floating image inside or outside a store space by transmitting the image through a transparent member that divides the space, such as the glass of a shop window. Also, apart from the above embodiments, a space-floating image display device is also provided that uses an optical system that includes a polarization separation member (in other words, a polarizing beam splitter, or simply a beam splitter) and a retroreflector, which will be described later, to display a space-floating image mainly indoors.

[0016] In the following description of the embodiments, an image floating in space is expressed by the term "space-floating image." Instead of this term, it may be expressed as "aerial image," "space-floating image," "space-floating optical image of displayed image," "space-floating optical image of displayed image," etc. The term "space-floating image" used in the description of the embodiments is used as a representative example of these terms.

[0017] According to the following embodiments, for example, high-resolution video information can be displayed floating in space on the glass surface of a shop window or a light-transmitting plate. Furthermore, the floating video display device of the embodiments can be installed in a relatively small space, such as on a desk in a study, on a table in a living room, or on a kitchen counter.

[0018] In the conventional floating image display device, an organic EL panel or a liquid crystal display panel is used as a high-resolution color display image source in combination with a retroreflective material. In the conventional floating image display device, the image light is diffused over a wide angle, which causes the following problems:

[0019] As shown in Figure 2B, in the retroreflective member 2, because the retroreflective member 2a is a hexahedron, in addition to the normally reflected light, there is a problem in that ghost images are generated by image light that is incident on the retroreflective member 2 at an angle, impairing the image quality of the floating image in space. The retroreflective member 2 is also called a retroreflective plate or retroreflective sheet.

[0020] Furthermore, as shown in Figure 5, the floating image obtained by reflecting the image light from the image display device, which is the image source, using the retroreflective member 2 has the problem that in addition to the ghost image mentioned above, blurring occurs in each pixel of the liquid crystal display panel.

[0021] FIG. 1 shows an example of a usage pattern and a configuration example of a space-floating image display device according to an embodiment. (A) of FIG. 1 shows the overall configuration of the space-floating image display device according to this embodiment. For example, in a store or the like, a space is partitioned by a show window (window glass) 105, which is a light-transmitting member (also referred to as a transparent member) such as glass. The space-floating information display device of this embodiment can transmit the transparent member 100 to display a space-floating image 3 in one direction toward the outside of the store space. Specifically, light with a narrow-angle directivity and specific polarization is emitted from the image display device 1 of the space-floating information display device as an image beam, enters the retroreflective member 2, is retroreflected, and transmits through the window glass 105 to form the space-floating image 3, which is a real image, outside the store space. (A) of FIG. 1 shows a case where, in the depth direction, the back side of the window glass 105 is the store space and the front side is the outside space (e.g., a sidewalk). On the other hand, by providing the window glass 105 with a means for reflecting a specific polarized wave (such as an optical member), it is possible to reflect the image light beam and form the floating image 3 in a desired position within the store.

[0022] FIG. 1B shows a block diagram of the image display device 1. The image display device 1 includes an image display unit 1a that displays the original image of the floating image 3, an image control unit 1b that converts the input image to match the resolution of the panel of the image display unit 1a, an image signal receiving unit 1c that receives the image signal, and a receiving antenna 1d. The image signal receiving unit 1c supports wired input signals such as USB (Universal Serial Bus: registered trademark) input and HDMI (High-Definition Multimedia Interface: registered trademark) input, as well as wireless input signals such as Wi-Fi (Wireless Fidelity: registered trademark). The image display device 1 can function independently as an image receiving and display device and can also display image information from an external PC, tablet, smartphone, etc. Furthermore, by connecting a stick PC or the like, the image display device 1 can be equipped with capabilities such as calculation processing and image analysis processing.

[0023] [V-type floating image display device] FIG. 2A shows an example of the configuration of the main components of a space-floating image display device according to one embodiment. The embodiment of FIG. 2A shows a configuration in which an image display device 1 and a retroreflective member (i.e., a retroreflector) 2 are arranged in a substantially V-shape (hereinafter referred to as a V-shape). As shown in FIG. 2A, in the V-shape configuration, an image display device 1 that generates image light of a specific polarization is provided in an oblique direction (a direction corresponding to optical axis A1) relative to a transparent member 100 such as flat glass (which is arranged horizontally in this example). Furthermore, a retroreflective member 2 is provided in another oblique direction (a direction corresponding to optical axis A2) relative to the transparent member 100 such as flat glass. The image display device 1 is composed of a light source device 13, a liquid crystal display panel 11 that is a liquid crystal display element, an absorptive polarizer 12, and the like.

[0024] 2A, image light of a specific polarization emitted from liquid crystal display panel 11 of image display device 1 travels in the direction of optical axis A1, is reflected by beam splitter 101 (polarization separation member) provided on transparent member 100 and has a film that selectively reflects image light of a specific polarization, travels in the direction of optical axis A2, and is incident on retroreflective member 2. In this example, beam splitter 101 is formed in a sheet shape and adhered to the underside of transparent member 100 such as flat glass. Alternatively, beam splitter 101 may be formed by directly evaporating an optical thin film onto flat glass.

[0025] A λ / 4 plate 21 is provided on the image light incident surface (in other words, the retroreflective surface) of the retroreflective member 2. In other words, the λ / 4 plate 21 is a polarization conversion element, a phase difference plate, and a quarter-wave plate.

[0026] The image light on optical axis A2 from the beam splitter 101 is made to pass through the λ / 4 plate 21 twice, once upon entering the retroreflective member 2 and once upon exiting the retroreflective member 2, and is thereby polarization-converted from a specific polarization (one polarization) to the other polarization. Here, the beam splitter 101, which selectively reflects image light of a specific polarization, has the property of transmitting image light of the other polarization after polarization conversion. Therefore, the image light of the other polarization after polarization conversion passes through the beam splitter 101. The image light that has passed through the beam splitter 101 forms and displays a real image, a floating-in-space image 3, at a predetermined position outside the transparent member 100 in the direction of optical axis A3, which corresponds to the optical axis A2.

[0027] The light that forms the floating image 3 in space is a collection of light rays that converge from the retroreflective member 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 in space. Therefore, in the configuration of FIG. 2A, when a user views the floating image 3 from direction A indicated by the arrow, which corresponds to the optical axis A3, the floating image 3 is perceived as a bright image. However, when viewed by another person from direction B indicated by the arrow, for example, the floating image 3 cannot be perceived as an image at all. These characteristics are extremely suitable for use in systems that display images that require high security or highly confidential images that should be concealed from people directly facing the user.

[0028] Depending on the performance of the retroreflective member 2, the polarization axis of the reflected image light may become misaligned. In this case, a portion of the image light with a misaligned polarization axis is reflected by the beam splitter 101 described above and returns to the image display device 1. This returned light may be re-reflected on the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating a ghost image and potentially degrading the image quality of the floating image 3. Therefore, in this embodiment, an absorbing polarizer 12 is provided on the image display surface of the image display device 1. The image light emitted from the image display device 1 is transmitted through the absorbing polarizer 12, and the reflected light returning from the beam splitter 101 is absorbed by the absorbing polarizer 12. This suppresses the re-reflection and prevents degradation of the image quality of the floating image 3 due to ghost images.

[0029] The above-mentioned beam splitter (polarization separation member) 101 is formed of, for example, a reflective polarizing plate or a metal multilayer film that reflects specific polarized waves. More specifically, the beam splitter 101 can be formed by evaporating an optical thin film onto flat glass (for example, quartz glass).

[0030] [Retroreflective material] 2B shows an example of the surface shape of a retroreflector as a typical retroreflective member 2. Light rays incident on the interior of regularly arranged triangular pyramidal prisms are reflected by the three wall surfaces and the bottom surface of the triangular pyramidal prisms and emitted as retroreflected light in a direction corresponding to the incident light, and a real floating image is displayed on the display device 1 based on the image displayed.

[0031] The resolution of the floating image 3 in space depends not only on the resolution of the LCD panel 11 but also on the outer diameter D and pitch P of the retroreflective area 2a (the area surrounded by a hexagon) of the retroreflective member 2 shown in FIG. 2B. For example, when using a 7-inch WUXGA (1920 × 1200 pixels) LCD panel 11, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective area 2a is 240 μm and the pitch P is 300 μm, one pixel of the floating image 3 will be equivalent to 300 μm. As a result, the effective resolution of the floating image 3 will be reduced to about one-third. Therefore, to make the resolution of the floating image 3 equivalent to that of the image display device 1, it is desirable to make the diameter D and pitch P of the retroreflective area 2a closer to that of one pixel of the LCD panel 11. On the other hand, in order to suppress the occurrence of moire caused by the retroreflective member 2 and the pixels of the liquid crystal display panel 11, it is advisable to design the pitch ratio of each so that it is not an integral multiple of one pixel. Also, it is advisable to arrange the shape so that none of the sides of the retroreflective area 2a overlaps with any of the sides of one pixel of the liquid crystal display panel 11.

[0032] [Z-type floating image display device] Fig. 3 shows an example of the configuration of the main parts of a space-floating image display device according to an embodiment different from the embodiment in Fig. 2A. The embodiment in Fig. 3 shows a configuration in which an image display device 1 and a retroreflective member 2 (retroreflective plate) are arranged opposite each other, and a beam splitter 101 is arranged in the space connecting them at an angle of about 45 degrees to the image display device 1 and the retroreflective member 2, roughly in a Z shape (or an inverted Z shape) (hereinafter referred to as Z shape).

[0033] The Z-type configuration shown in Fig. 3 includes a transparent member 100 such as a glass plate and an absorptive polarizer 112 for the purpose of reducing the effect of external light incident from direction C on the retroreflective member 2 and image display device 1. As shown in Fig. 3, the image display device 1 and retroreflective member 2 are disposed at an angle of approximately 90 degrees to the transparent member 100 and the absorptive polarizer 112, and at an angle of approximately 45 degrees to the beam splitter 101. In this embodiment, the beam splitter 101 is disposed horizontally, and the position of the image displayed on the image display device 1, more specifically the liquid crystal display panel 11, and the position where the floating image 3 is formed are plane-symmetrical to the beam splitter 101.

[0034] <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. 4A. The optical system of FIG. 4A is an optical system that uses a retroreflector 5 that is different from the retroreflector 2 used in FIGS. 2A, 2B, and 3. Another example of the configuration 3 of the optical system will be described in more detail below with reference to FIGS. 4A to 4F. In FIG. 4A, components that are assigned the same reference numerals as those in FIGS. 2A, 2B, and 3 have the same functions and configurations as those in FIGS. 2A, 2B, and 3. Such components will not be described repeatedly to simplify the explanation.

[0035] 4A is a diagram showing an example of the configuration of the main components and the retroreflecting portion of a space floating image display device according to one embodiment of the present invention. A display device 10 that emits image light is provided obliquely on a transparent member 100 such as glass. The display device 10 includes a liquid crystal display panel 11 and a light source device 13 that generates light.

[0036] A chief ray 9020 representing the light beam emitted from the display device 10 travels toward the retroreflector 5 and is incident on the retroreflector 5 at an incident angle α. The incident angle α may be, for example, 45°. However, the incident angle α is not limited to 45°, and may also be, for example, 45°±15°.

[0037] 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.

[0038] 4B, 4C, etc., the principal ray 9020 travels in the z direction and is retroreflected in the x and y directions by the retroreflector 5. As a result, the reflected ray 9021 travels in a direction away from the retroreflector 5 along an optical path that is mirror-symmetrical with respect to the principal ray 9020 with the retroreflector 5 as the reference, passes through the transparent member 100, and forms the floating image 3 in space as a real image on the imaging plane.

[0039] The light beam that forms the space-floating image 3 is a collection of light rays that converge from the retroreflector 5 to the optical image of the space-floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the space-floating image 3. Therefore, the space-floating image 3 is an image with high directionality, unlike a diffuse image formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 4A, when a user views the space-floating image 3 from the direction of arrow A, the space-floating image 3 is perceived as a bright image. However, when another person views the space-floating image 3 from the direction of arrow B, the space-floating image 3 cannot be perceived as an image at all. This characteristic is suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0040] An example of the configuration of the retroreflector 5 will be described using Figures 4B and 4C. 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 multifaceted reflector array. The specific configuration of the corner reflector 9040 will be described in detail using Figures 4D, 4E, and 4F. 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.

[0041] 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.

[0042] Next, the configuration and effects of the corner reflector 9040 that constitutes the retroreflector 5 will be described with reference to Figures 4D, 4E, and 4F. 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.

[0043] 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).

[0044] 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.

[0045] 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.

[0046] 2A, 2B, and 3, 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 floating image 3. The traveling direction of the chief ray of the convergent reflected light beam reflected from the retroreflector 2 is opposite to the traveling direction of the chief ray of the diffusive incident light beam that is incident on the retroreflector 2.

[0047] 4A, 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.

[0048] 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.

[0049] 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.

[0050] The surface shape of the retroreflector according to this embodiment is not limited to the above example. Various surface shapes that achieve retroreflection may be used. Specifically, the surface of the retroreflector according to this embodiment may be provided with retroreflection elements in which triangular pyramidal prisms, hexagonal pyramidal prisms, other polygonal prisms, or a combination thereof are periodically arranged. Alternatively, the surface of the retroreflector according to this embodiment may be provided with retroreflection elements in which these prisms are periodically arranged to form cube corners. These may also be referred to as corner reflector arrays or polyhedral reflector arrays. Alternatively, the surface of the retroreflector according to this embodiment may be provided with capsule lens-type retroreflection elements in which glass beads are periodically arranged. The detailed configuration of these retroreflection elements can be achieved using existing technology, so a detailed description will be omitted. Specifically, the techniques disclosed in Japanese Patent Laid-Open Nos. 2001-33609, 2001-264525, 2005-181555, 2008-70898, and 2009-229942 may be used.

[0051] The inventors conducted experiments to determine the relationship between the amount of blur l (small L) and pixel size L (large L) of the image of the floating image 3 that is acceptable for improving visibility. The image display device 1 was created by combining a liquid crystal display panel 11 with a pixel pitch of 40 μm and a light source device 13 with a narrow divergence angle (divergence angle of 15°) as in this embodiment. Figure 5 shows the experimental results. It was found that the amount of blur l, which deteriorates visibility, is preferably 40% or less of the pixel size, and is barely noticeable if it is 15% or less. The surface roughness of the reflective surface at which the amount of blur l is acceptable is an average roughness of 160 nm or less within a measurement distance of 40 μm. To achieve a less noticeable amount of blur l, it was found that a surface roughness of 120 nm or less is desirable. Therefore, it is desirable to reduce the surface roughness of the retroreflective member 2 described above and to keep the surface roughness, including the reflective film and its protective film, that form the reflective surface below the above-mentioned value.

[0052] On the other hand, to manufacture the retroreflective member 2 at low cost, it is preferable to use a roll press method. Specifically, this method involves aligning the retroreflective members 2a and forming them on a film. In this method, the reverse shape of the shape to be formed is formed on the surface of a roll, a UV-curable resin is applied to a base material for fixing, and the required shape is formed by passing the roll through the rolls. The resin is then irradiated with UV light to harden it, and the retroreflective member 2 of the desired shape is obtained.

[0053] The image display device 1 of this embodiment, using the liquid crystal display panel 11 and the light source device 13 (see FIG. 6 for details) as a light source that generates light of a specific polarization, reduces the possibility of image light being incident obliquely on the retroreflective member 2. As a result, the occurrence of ghost images is suppressed, and even if a ghost image occurs, the brightness of the ghost image is low, resulting in a structurally excellent system.

[0054] 3, the image display device 1, which is configured with a liquid crystal display panel 11, an absorptive polarizer 12, and a light source device 13, is disposed at a predetermined angle (for example, about 45 degrees with respect to the beam splitter 101 in the horizontal plane). The image light from the image display device 1 passes through the beam splitter 101 in the direction of optical axis B1 (diagonal to the beam splitter 101), and travels toward the retroreflective member 2 in the direction of optical axis B2 (corresponding to direction D) that corresponds to the optical axis B1.

[0055] Here, the image light from the image display device 1 is light of a specific polarization, for example, image light having the characteristics of P polarization (parallel polarization). The beam splitter 101 is a polarization separation member such as a reflective polarizer, and has the property of transmitting P polarization image light from the image display device 1 but reflecting S polarization (vertical polarization: Senkrecht polarization) image light. The beam splitter 101 is formed from a reflective polarizer or a metal multilayer film that reflects specific polarization. The beam splitter 101 can generally be formed by evaporating an optical thin film on a flat glass substrate. Therefore, the refractive index of the beam splitter 101 is substantially the same as the refractive index n of flat glass (n≈1.5).

[0056] Meanwhile, a λ / 4 plate 21 is provided on the light incident surface (retroreflective surface) of the retroreflective member 2. P-polarized image light transmitted through the beam splitter 101 from the image display device 1 passes through the λ / 4 plate 21 twice in total, upon entering and exiting the retroreflective member 2, and is thereby converted from P-polarized to S-polarized light. As a result, the polarization-converted S-polarized image light from the retroreflective member 2 is reflected by the beam splitter 101 and travels toward the transparent member 100, etc. The reflected S-polarized image light travels in a direction corresponding to the optical axis B3 (a diagonal direction relative to the beam splitter 101), passes through the transparent member 100, such as a glass plate, and the absorptive polarizer 112, and generates and displays a real image, a floating-in-space image 3, at a predetermined position outside the transparent member 100, etc.

[0057] Here, in order to reduce degradation of image quality caused by sunlight or illumination light incident on an optical system composed of optical components such as the image display device 1, retroreflective member 2, and beam splitter 101, it is advisable to provide an absorptive polarizing plate 112 on the outer surface of the transparent member 100. Since the polarization axis may become misaligned when light is retroreflected by the retroreflective member 2, some of the image light may be reflected by the beam splitter 101 and returned to the image display device 1. This returned light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating a ghost image and significantly degrading the image quality of the spatial floating image 3.

[0058] 2A and 3, an absorptive polarizer 12 is provided on the image display surface of the image display device 1. Alternatively, an anti-reflection film (not shown) may be provided on the image output side of the absorptive polarizer 12 provided on the surface of the image display device 1. This allows the absorptive polarizer 12 to absorb light that causes ghost images, thereby preventing degradation of image quality of the spatially floating image 3 due to ghost images.

[0059] Furthermore, in the Z-shaped configuration of FIG. 3, when external light directly enters the retroreflective member 2, a strong ghost image is generated. Therefore, to suppress and prevent the generation of this ghost image, in this embodiment, the retroreflective member 2 is tilted downward relative to the direction of incidence of the external light, thereby blocking the incidence of the external light. Specifically, the main incident direction of the external light is set to a direction (diagonal direction like the optical axis B3) corresponding to direction C indicated by the arrow (the direction in which the user views the floating image 3 from the front). In this case, the retroreflective member 2 is arranged so that the optical axis B2 is at an angle of, for example, about 90 degrees relative to direction C (optical axis B3). In other words, the main surface of the retroreflective member 2 is arranged so that the main surface of the transparent member 100 or the like is at an angle of, for example, about 90 degrees. As a result, external light incident in direction C does not directly enter the main surface (retroreflective surface) of the retroreflective member 2, thereby preventing the generation of ghost images.

[0060] Furthermore, the image display device 1 is also disposed in a direction different from the incident direction of external light (direction C). Specifically, the main surface (image light exit surface) of the image display device 1 is disposed in the same direction as (i.e., parallel to) the main surface of the retroreflective member 2, and the optical axis B1 of the image display device 1 is disposed at an angle of approximately 90 degrees with respect to the optical axis B3 corresponding to the incident direction of external light (direction C). Furthermore, when considering the range of the luminous flux when external light is incident in direction C on the main surface of the transparent member 100 functioning as an opening, the image display device 1 is disposed at a position slightly outside that range. These features reduce the occurrence of ghost images caused by re-reflection at the image display device 1.

[0061] [Video display device] FIG. 6 shows an example of the configuration of an image display device 1 that can be applied to the embodiments of FIGS. 2A and 3. This image display device 1 is configured to include a light source device 13, a liquid crystal display panel 11, a light redirection panel 54, etc. The image output surface side of the liquid crystal display panel 11 may be provided with the aforementioned absorptive polarizer 12. The light source device 13 is configured to include a plurality of LED elements 201 (LEDs: Light Emitting Diodes), which are semiconductor light sources (solid-state light sources) that make up the light source, and a light guide 203, etc. FIG. 6 shows an exploded perspective view of the liquid crystal display panel 11 and the light redirection panel 54 arranged on the light output side of the light source device 13.

[0062] Light source device 13 is formed, for example, from a plastic case (not shown) and is configured to house LED elements 201 and light guide 203 inside. Light-receiving end surface 203a is provided on the light incident side of light guide 203 to convert divergent light from each LED element 201 into a substantially parallel beam. Light-receiving end surface 203a has a shape in which the cross-sectional area gradually increases toward the side opposite the light-receiving portion, and is provided with a lens shape that has the effect of gradually reducing the divergence angle by multiple total reflections as light propagates inside.

[0063] Furthermore, the liquid crystal display panel 11 is attached to the upper surface of the light guide 203, and is disposed approximately parallel to the light guide 203. The upper surface of the light guide 203 serves as an emission surface that emits light reflected by the light guide 203. Furthermore, a plurality of LED elements 201 are attached to one side surface (the lower side surface in FIG. 6) of the case of the light source device 13. The light from the plurality of LED elements 201 is converted into approximately collimated light (approximately parallel light) by the shape of the light-receiving end surface 203a of the light guide 203. For this reason, the light-receiving portion of the light-receiving end surface 203a and the LED elements 201 are attached while maintaining a predetermined positional relationship.

[0064] The light source device 13 is configured by attaching a light source unit, in which a plurality of LED elements 201 serving as light sources are arranged, to a light-receiving end surface 203a, which is a light-receiving section provided on the light incident side of a light guide 203. The divergent light beam from the LED elements 201 is converted into approximately collimated light by the lens shape of the light-receiving end surface 203a of the light guide 203. This approximately collimated light is guided inside the light guide 203 in direction A indicated by the arrow. Direction A is a direction approximately parallel to the liquid crystal display panel 11 (from bottom to top in the drawing). The light guided in direction A has its direction converted by a light beam direction conversion section 204 provided in the light guide 203, and is emitted in direction B indicated by the arrow toward the liquid crystal display panel 11, which is approximately parallel to the light guide 203. Direction B is a direction approximately perpendicular to the display surface of the liquid crystal display panel 11.

[0065] The light guide 203 has a configuration in which the distribution (in other words, density) of the light beam direction conversion portions 204 is optimized by the shape inside or on the surface of the light guide 203. This makes it possible to control the uniformity of light, which is the light beam emitted from the light source device 13 shown in direction B and incident on the liquid crystal display panel 11.

[0066] Furthermore, in the image display device 1 including the light source device 13 and the liquid crystal display panel 11, the directivity of the light emitted from the light source device 13 in the direction B can be controlled to improve the utilization efficiency of the light flux emitted from the light source device 13 in the direction B and significantly reduce power consumption. More specifically, a light source having a narrow divergence angle can be configured as the light source device 13. As a result, the image light from the image display device 1 reaches the viewer efficiently with high directivity (in other words, linearity) like laser light, and a high-quality floating image can be displayed with high resolution. At the same time, the power consumption of the image display device 1 including the LED elements 201 of the light source device 13 can be significantly reduced.

[0067] The liquid crystal display panel 11 is attached to a frame (not shown) of the liquid crystal display panel 11, which is attached to the top surface of a case (not shown) of the light source device 13. The liquid crystal display panel 11 is attached to the frame, and a flexible printed circuit (FPC) (not shown) and the like are attached, which are electrically connected to the liquid crystal display panel 11. The liquid crystal display panel 11, which is a liquid crystal display element, generates a display image together with the LED elements 201 by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes the electronic device.

[0068] Next, a desk-mounted type space-floating image display device according to one embodiment will be described with reference to Fig. 7 and subsequent figures. The space-floating image display device of each embodiment shown in Fig. 7 to Fig. 9 corresponds to the V-type configuration shown in Fig. 2A as a basic configuration.

[0069] [First Example] FIG. 7 shows an example of the configuration of the main parts of a space floating image display device 400 suitable for installation on a desk, according to one embodiment (hereinafter referred to as a first embodiment).

[0070] 7 shows a cross-sectional view of the space-floating image display device 400 as seen from the side. The front of the device here is the surface corresponding to the direction in which the space-floating images 3 (3A, 3B) formed by the space-floating image display device 400 can be viewed by the user (230A, 230B) from the front.

[0071] The directions AA and AB are directions in which the user views the floating images 3 (3A, 3B) from the front, and correspond to the negative direction in the Y direction.

[0072] For the purpose of explanation, a coordinate system or direction such as (X, Y, Z) shown in the figure may be used. In this figure, the Z direction is the vertical direction, up and down direction, the X direction and the Y direction are two horizontal directions that intersect at right angles, the X direction is the depth direction, front and back direction (the horizontal direction from front to back within the screen of the floating image 3), and the Y direction is the left and right direction (the horizontal direction from left to right within the screen of the floating image 3).

[0073] 7 has the same positional relationship of the components (image display device 1, beam splitter 101A, transparent member 100A, retroreflective member 2, etc.) as the V-shaped configuration of FIG. 2A. In addition, image display device 1 includes a liquid crystal display panel 11 and a light source device 13.

[0074] In the following description, the beam splitter 101A and the transparent member 100A will be treated as a single unit, and the transparent member will be abbreviated. Other similar components will also be abbreviated in the same manner.

[0075] In order to form the space-floating image 3A, the components of the space-floating image display device 400 (image display device 1, beam splitter 101A, retroreflective member 2, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101A, retroreflective member 2, etc. in Fig. 7 are arranged with a predetermined positional relationship so as to form a V-shape, similar to the configuration in Fig. 2A. The formed space-floating image 3A can be viewed from the front by the user 230A in the direction AA.

[0076] The floating-in-the-air image display device 400 of the first embodiment shown in Fig. 7 is provided with a hinge mechanism 330 serving as a rotation fulcrum at one end of the beam splitter 101A. The hinge mechanism 330 does not move up, down, left, or right, but is free to rotate; it is provided in the X direction at the left end of the beam splitter 101A, and the beam splitter 101A is configured to rotate up and down around the hinge mechanism 330 as a rotation fulcrum. In other words, the floating-in-the-air image display device shown in Fig. 7 is provided with a display panel that displays an image, a polarization separation member that reflects a portion of the image light emitted from the display panel, and a retroreflection member that retroreflects the reflected light from the polarization separation member, and the reflected light retroreflected by the retroreflection member passes through the polarization separation member to form a floating-in-the-air image, and the angle of the polarization separation member relative to the display panel and the retroreflection member is variable.

[0077] That is, the structure allows the beam splitter 101A and the transparent member 100A to be positioned at different angles relative to the fixed position of the image display device 1 and the retroreflective member 2. Alternatively, the structure allows the beam splitter 101A and the transparent member 100A to be rotated around the hinge mechanism 330 as a rotation fulcrum, thereby changing the separation distance between the beam splitter 101A and the image display device 1, and between the beam splitter 101A and the retroreflective member 2. Even if the positioning angle of the beam splitter 101A and the transparent member 100A is different, they are positioned with a positional relationship to form a V-shape, similar to the configuration in FIG. 2A.

[0078] 7, the beam splitter 101A and the transparent member 100A are rotated upward by an angle γ with respect to the horizontal position (XY plane) around the hinge mechanism 330 as a rotation fulcrum, and are placed at the position of the beam splitter 101B and the transparent member 100B. In this arrangement, the image light from the image display device 1 passes through an optical axis AB1, which is longer than the optical axis A1, is reflected by the beam splitter 101B, passes through the λ / 4 plate 21 along the optical axis AB2, and is incident on the retroreflective member 2.

[0079] The image light that is retroreflected by the retroreflective member 2 and emitted passes through the λ / 4 plate 21 again, where it is converted into the other polarized wave, and then passes through the beam splitter 101B. The image light that passed through the beam splitter 101B forms and displays a real image, a floating-in-space image 3B, at a predetermined position outside the transparent member 100B in the direction of the optical axis AB3 corresponding to the optical axis AB2. The formed floating-in-space image 3B can be viewed as a bright image by the user 230B in a frontal position from the direction AB indicated by the arrow corresponding to the optical axis AB3.

[0080] Since beam splitter 101B is positioned above beam splitter 101A by angle γ, the length of optical axis AB1 from image display device 1 to beam splitter 101B is longer than optical axis A1 from image display device 1 to beam splitter 101A, and floating image 3B is formed at a higher position than floating image 3A. Therefore, when the height of the viewpoint varies depending on the height difference between users, it is possible to form floating image 3B at a position that is easy to view by changing the tilt angle of beam splitter 101.

[0081] In the embodiment of FIG. 7, beam splitter 101A in a horizontal position forms a floating image 3A that is optimal for user 230A, whereas beam splitter 101B tilted upward by an angle γ relative to the horizontal position (XY plane) forms a floating image 3B that is suitable for user 230B, who is taller than user 230A.

[0082] [Second Example] FIG. 8 shows a configuration example of a space floating image display device 400 suitable for installation on a desk, according to one embodiment (hereinafter referred to as a second embodiment).

[0083] FIG. 8 shows a cross-sectional view of the space floating image display device 400 as seen from the side.

[0084] 7 is placed in a housing 4001, and the housing 4001 has an opening (opening hole) 4002 in the horizontal direction (parallel to the XY plane). The hinge mechanism 330 is provided at one end of the opening 4002, and rotatably holds the beam splitter 101A on one side of the beam splitter 101A opposite to the user 230, and serves as a rotation fulcrum for the beam splitter 101A.

[0085] The space floating image display device 400 also includes a control unit 500 having control functions, an imaging unit 510, and a piston mechanism 310 that moves the piston up and down or expands and contracts.

[0086] In Figure 8, the positional relationship of the components (image display device 1, beam splitter 101A and transparent member 100A, retroreflective member 2, etc.) is the same as that of the V-shaped configuration in Figure 7. Note that, hereinafter, beam splitter 101A and transparent member 100A will be treated as a single unit, and the transparent member will sometimes be abbreviated. Other similar components will also sometimes be abbreviated in the same way.

[0087] In order to form the space-floating image 3A, the components of the space-floating image display device 400 (image display device 1, beam splitter 101A, retroreflective member 2, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101A, retroreflective member 2, etc. in Fig. 8 are arranged with a predetermined positional relationship so as to form a V-shape, similar to the configuration in Fig. 7. The formed space-floating image 3A can be viewed from the front by the user 230A in the direction AA.

[0088] This is an example of a structure in which beam splitter 101A rotates or moves up and down around hinge mechanism 330 as a rotation fulcrum. That is, this structure allows beam splitter 101A and transparent member 100A to be positioned at different angles while image display device 1 and retroreflective member 2 are fixed. Alternatively, this structure allows beam splitter 101A and transparent member 100A to be rotated around hinge mechanism 330 as a rotation fulcrum, thereby changing the distance between beam splitter 101A and image display device 1 and the distance between beam splitter 101A and retroreflective member 2. In other words, the floating image display device shown in Figure 8 comprises a display panel that displays an image, a polarization separation member that reflects a portion of the image light emitted from the display panel, and a retroreflective member that retroreflects the reflected light from the polarization separation member, and the reflected light retroreflected by the retroreflective member passes through the polarization separation member to form a floating image, and the angle of the polarization separation member relative to the display panel and the retroreflective member is variable.

[0089] Piston mechanism 310 is disposed on the side of beam splitter 101A and transparent member 100A that faces hinge mechanism 330. In the initial state, the piston of piston mechanism 310 is in contact with one side of beam splitter 101A and transparent member 100A over the length of piston 310A, holding beam splitter 101A and transparent member 100A horizontally (parallel to the XY plane). When piston 310A of piston mechanism 310 extends and becomes piston 310B, beam splitter 101A and transparent member 100A rotate upward by angle γ with respect to the horizontal position (XY plane) around hinge mechanism 330 as the rotation fulcrum, and move to the position of beam splitter 101B and transparent member 100B. That is, the piston mechanism 310 rotates the beam splitter 101A around the hinge mechanism 330 of the rotation axis as a rotation fulcrum, and the angle with respect to the image display device 1 and the retroreflective member 2 can be changed.

[0090] At the positions of beam splitter 101B and transparent member 100B, the image light from image display device 1 travels along optical axis AB1, which is longer than optical axis A1, is reflected by beam splitter 101B, passes through λ / 4 plate 21 along optical axis AB2, and enters retroreflective member 2. The image light retroreflected by retroreflective member 2 passes through λ / 4 plate 21 again, is converted to the other polarization, and transmits beam splitter 101B. The image light transmitted through beam splitter 101B forms and displays space-floating image 3B, which is a real image, at a predetermined position outside transparent member 100B in the direction of optical axis AB3 corresponding to optical axis AB2. The formed space-floating image 3B can be viewed as a bright image by user 230B in a frontal position from direction AB indicated by the arrow corresponding to optical axis AB3.

[0091] The arrangement of piston mechanism 310 is not limited to this embodiment, and similar effects can be obtained by arranging it on other sides of beam splitter 101A and transparent member 100A or in multiple positions. Furthermore, the method of rotating or driving beam splitter 101A in the vertical direction around hinge mechanism 330 as a rotation fulcrum is not limited to piston mechanism 310.

[0092] (Regarding the imaging unit, control unit, etc.) The imaging unit 510 captures images of the height, face, eyes, mouth, and other facial components of the user 230, and information such as the height and face of the user 230 is input to the control unit 500. The imaging unit 510 detects, for example, the position of the eyes of the user 230 from the input information of the user 230, and obtains information about the height of the user's 230 eyes.

[0093] If the obtained eye height information of the user 230 differs from the pre-determined viewing height, the control unit etc. 500 can drive the piston mechanism 310 to change the angle of the beam splitter 101A to a position that is optimal for the user 230's viewing.

[0094] For example, if user 230A is at a predetermined viewing height, image capturing unit 510 and control unit 500 etc. control piston mechanism 310 so that beam splitter 101A holds the horizontal position. In the case of user 230B who is taller than user 230A, image capturing unit 510 and control unit 500 etc. extend piston 310A of piston mechanism 310 to piston 310B, and change the position of beam splitter 101A to that of beam splitter 101B tilted by angle γ, so that user 230B can view a bright image from a frontal position.

[0095] [Third Example] FIG. 9 shows an example of the configuration of a space floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as a third embodiment).

[0096] 9 shows a cross-sectional view of the space-floating image display device as seen from the side. In this embodiment, a space-floating image display device 400 is disposed in a housing 4001.

[0097] 9, the positional relationship of the components (image display device 1, beam splitter 101A and transparent member 100A, retroreflective member 2, etc.) is the same as that of the V-shaped configuration in FIG. 2A. Note that, hereinafter, beam splitter 101A and transparent member 100A will be treated as a single unit, and the transparent member will sometimes be abbreviated. Other similar components will also sometimes be abbreviated in the same way.

[0098] In order to form the space-floating image 3A, the components of the space-floating image display device (image display device 1, beam splitter 101A, retroreflective member 2, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101A, retroreflective member 2, etc. in Fig. 9 are arranged with a predetermined positional relationship so as to form a V-shape, similar to the configuration in Fig. 2A. The formed space-floating image 3A can be viewed from the front by user 230A in direction AA.

[0099] 9, the hinge mechanism 331 is provided near the center of the opening 4002, and rotatably holds both ends of the beam splitter 101A at or near the center line of the beam splitter 101A, which is parallel to one side of the beam splitter 101A facing the user 230, and serves as a rotation fulcrum for the beam splitter 101A. The hinge mechanism 331 does not move up and down or left and right, but is free to rotate, and the beam splitter 101A rotates up and down with the hinge mechanism 331 as the rotation fulcrum. In other words, the floating image display device shown in Figure 9 comprises a display panel that displays an image, a polarization separation member that reflects a portion of the image light emitted from the display panel, and a retroreflective member that retroreflects the reflected light from the polarization separation member, and the reflected light retroreflected by the retroreflective member passes through the polarization separation member to form a floating image, and the angle of the polarization separation member relative to the display panel and the retroreflective member is variable.

[0100] That is, the structure allows the beam splitter 101A and the transparent member 100A to be positioned at different angles relative to the fixed position of the image display device 1 and the retroreflective member 2. Alternatively, the beam splitter 101A and the transparent member 100A can be rotated around the hinge mechanism 331 as a rotation fulcrum, thereby changing the separation distance between the beam splitter 101A and the image display device 1, and between the beam splitter 101A and the retroreflective member 2. Even if the positioning angle of the beam splitter 101A and the transparent member 100A is different, they are positioned in a positional relationship to form a V-shape, similar to the configuration in FIG. 2A.

[0101] Piston mechanism 310 is disposed on the side of beam splitter 101A and transparent member 100A facing user 230. In the initial state, the piston of piston mechanism 310 is in contact with one side of beam splitter 101A and transparent member 100A over the length of piston 310A, holding beam splitter 101A and transparent member 100A horizontally (parallel to the XY plane). When piston 310A of piston mechanism 310 extends to the piston 310C state, beam splitter 101A and transparent member 100A rotate upward by angle γ relative to the horizontal position (XY plane) around hinge mechanism 331 as the rotation fulcrum, and move to the position of beam splitter 101C and transparent member 100C. In other words, piston mechanism 310 rotates beam splitter 101A around hinge mechanism 331, which is the rotation axis, as the rotation fulcrum, allowing the angle with respect to image display device 1 and retroreflective member 2 to be changed.

[0102] In this arrangement, image light from the center position of image display device 1 is reflected or passes along the optical axes A1, A2, and A3 on the rotation fulcrum axis (X-axis direction) of hinge mechanism 331 of beam splitter 101A. Even when beam splitter 101A and transparent member 100A rotate by an angle and the image light comes to the positions of beam splitter 101C and transparent member 100C, the path and length of the optical path of the image light from the center position of image display device 1 remains almost unchanged, so the light is reflected by beam splitters 101A and 101C, passes through λ / 4 plate 21 along optical axis A2, and enters retroreflective member 2.

[0103] The image light that is retroreflected by retroreflective member 2 and emitted passes through λ / 4 plate 21 again, where it is converted into the other polarized wave, and then passes through beam splitters 101A and 101C. The image light that passes through beam splitters 101A and 101C generates a floating image in space, which is a real image, at a predetermined position outside transparent members 100A and 100C in the direction of optical axis A3 corresponding to optical axis A2, and the floating image in space is generated at approximately the same position, so that floating images in space 3A and 3C almost overlap.

[0104] In this arrangement, let us consider image light from a position away from the center of image display device 1. Image light with optical axis A11 at the bottom end (left end in FIG. 9) of image display device 1 is reflected by beam splitter 101A, passes through λ / 4 plate 21 along optical axis A12, and enters retroreflective member 2. The image light retroreflected by retroreflective member 2 passes through λ / 4 plate 21 again, is converted to the other polarized wave, and transmits through beam splitter 101A. The image light transmitted through beam splitter 101A generates a real image, a floating-in-space image 3A, at a predetermined position outside transparent member 100A in the direction of optical axis A13, which corresponds to optical axis A12.

[0105] Next, when beam splitter 101A and transparent member 100A rotate by angle γ and reach the position of beam splitter 101C and transparent member 100C, the image light of optical axis A11 at the lower end of image display device 1 is reflected by beam splitter 101C, passes through λ / 4 plate 21 along optical axis C12, and enters retroreflective member 2. The image light retroreflected by retroreflective member 2 passes through λ / 4 plate 21 again, is converted to the other polarized wave, and transmits beam splitter 101C. The image light transmitted through beam splitter 101C generates a real image, a floating-in-space image 3C, at a predetermined position outside transparent member 100C in the direction of optical axis C13, which corresponds to optical axis C12.

[0106] Because the distance between the bottom end of the image display device 1 and the beam splitter 101C becomes shorter than the distance between the image display device 1 and the beam splitter 101A due to the rotation of the angle γ, in other words, the optical path distance becomes shorter, so that the position of the top end (left end in FIG. 9) of the generated floating-in-space image 3C becomes lower than the position of the top end of the floating-in-space image 3A. When the image light of the optical axis A21 at the top end (right end in FIG. 9) of the image display device 1 is reflected by the beam splitter 101A, it passes through the λ / 4 plate 21 along the optical axis A22 and enters the retroreflective member 2. The image light retroreflected by the retroreflective member 2 passes through the λ / 4 plate 21 again, is converted into the other polarized wave, and transmits through the beam splitter 101A. The image light transmitted through beam splitter 101A generates a real image, a floating image 3A, at a predetermined position outside transparent member 100A in the direction of optical axis A23 corresponding to optical axis A22.

[0107] Next, when beam splitter 101A and transparent member 100A rotate by angle γ and reach the position of beam splitter 101C and transparent member 100C, the image light of optical axis A21 at the upper end of image display device 1 is reflected by beam splitter 101C, passes through λ / 4 plate 21 along optical axis C22, and enters retroreflective member 2. The image light retroreflected by retroreflective member 2 passes through λ / 4 plate 21 again, is converted into the other polarized wave, and transmits beam splitter 101C. The image light transmitted through beam splitter 101C generates a real image, a floating-in-space image 3C, at a predetermined position outside transparent member 100C in the direction of optical axis C23, which corresponds to optical axis C22.

[0108] Due to the rotation of angle γ, the distance between the upper end of image display device 1 and beam splitter 101C becomes longer than the distance between image display device 1 and beam splitter 101A, in other words, the optical path distance becomes longer, so that the position of the lower end (left end in FIG. 9) of the generated floating-in-space image 3C becomes higher than the position of the upper end of the floating-in-space image 3A.

[0109] In other words, floating in space image 3C is tilted counterclockwise more than floating in space image 3A, or the tilt angle of floating in space image 3C is shallower and closer to the horizontal plane than floating in space image 3A. Floating in space image 3C can be seen as a bright floating in space image from a frontal position in the direction AC indicated by the arrow by user 230C, who is taller or has a higher viewpoint than user 230A.

[0110] [Fourth Example] Next, a block diagram of the internal configuration of the space floating image display device 400 will be described.

[0111] 10 is a block diagram showing an example of the internal configuration of the space-floating image display device 400. The space-floating image display device 400 includes a retroreflective member 2, a liquid crystal display panel 11, a light guide 203, a light source device 13, 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 video control unit 1160, a storage unit 1170, an imaging unit 510, a beam splitter 101, a beam splitter angle adjustment unit 1010, and the like.

[0112] Here, the beam splitter angle adjustment unit 1010 includes the piston mechanism 310 shown in FIG. 8 and FIG.

[0113] It should be noted that a removable media interface 1134, an attitude sensor 1113, a transmissive self-luminous image display device (not shown), a second display device (not shown), a secondary battery 1112, or the like may also be provided.

[0114] Each component of the space floating image display device 400 is disposed in a housing 4001. Note that the imaging unit 510 and the mid-air operation detection sensor 1351 may be provided outside the housing 4001.

[0115] The retroreflective member 2 retroreflects the light modulated by the liquid crystal display panel 11. Of the light reflected from the retroreflective member 2, the light output to the outside of the space-floating image display device 400 forms the space-floating image 3.

[0116] The liquid crystal display panel 11 is a display unit that generates an image by modulating transmitted light based on an input video signal under the control of a video control unit 1160 (described later). For example, a transmissive liquid crystal panel is used as the liquid crystal display panel 11. Alternatively, for example, a reflective liquid crystal panel that modulates reflected light or a DMD (Digital Micromirror Device: registered trademark) panel may be used as the liquid crystal display panel 11.

[0117] The light source device 13 supplies light to the liquid crystal display panel 11 and is a solid-state light source such as an LED light source or a laser light source. The power supply 1106 converts AC current input from the outside via the external power supply input interface 1111 into DC current and supplies power to the light source device 13. The power supply 1106 also supplies the necessary DC current to each part within the space floating image display device 400.

[0118] The secondary battery 1112 stores the power supplied from the power source 1106. Furthermore, when power is not supplied from the outside, the secondary battery 1112 supplies power to the light source device 13 and other components that require power via the external power input interface 1111. In other words, when the space-floating image display device 400 is equipped with the secondary battery 1112, the user can use the space-floating image display device 400 even when power is not supplied from the outside.

[0119] The light guide 203 guides the light generated by the light source device 13 and irradiates it onto the liquid crystal display panel 11. A combination of the light guide 203 and the light source device 13 can also be called a backlight for the liquid crystal display panel 11. The light guide 203 may be configured mainly using glass. The light guide 203 may be configured mainly using plastic. The light guide 203 may be configured using a mirror. Various methods are possible for combining the light guide 203 with the light source device 13.

[0120] The mid-air operation detection sensor 1351 is a sensor that detects an operation on the floating in space image 3 by the finger of the user 230. The mid-air operation detection sensor 1351 senses, for example, the entire display range of the floating in space image 3 and the range that overlaps with it.

[0121] The aerial operation detection sensor 1351 may sense only an area that overlaps with at least a portion of the display area of the floating image 3. Specific examples of the aerial operation detection sensor 1351 include distance sensors that use invisible light such as infrared rays, invisible light lasers, ultrasonic waves, etc. The aerial operation detection sensor 1351 may also be configured to combine multiple sensors and detect coordinates on a two-dimensional plane. 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.

[0122] The mid-air operation detection sensor 1351 only needs to be capable of sensing to detect touch operations, etc., made by the user with his / her finger on an object displayed as the floating-in-space image 3. Such sensing can be performed using existing technology.

[0123] The aerial operation detection unit 1350 acquires a sensing signal from the aerial operation detection sensor 1351, and based on the sensing signal, determines whether or not the finger of the user 230 has made contact with an object in the floating in space image 3, and calculates the position (contact position) where the finger of the user 230 has made contact with the object. The aerial operation detection unit 1350 is configured with a circuit such as an FPGA (Field Programmable Gate Array), for example. Furthermore, some of the functions of the aerial operation detection unit 1350 may be realized by software, for example, by a spatial operation detection program executed by the control unit 1110.

[0124] 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 400, or may be provided externally as a separate entity from the space-floating image display device 400. When provided as a separate entity from the space-floating image display device 400, 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 400 via a wired or wireless communication connection path or a video signal transmission path.

[0125] Furthermore, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be provided separately. This makes it possible to build a system in which the air-floating image display device 400 without an aerial operation detection function is used as the main body, and only the aerial operation detection function can be added as an option.

[0126] 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 400. 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 400, there is an advantage to a configuration in which only the aerial operation detection sensor 1351 is a separate unit.

[0127] The imaging unit 510 is a camera having an image sensor, and captures images of the face, eyes, arms, fingers of the user 230 and / or the space around the floating image 3 in space.

[0128] For example, height information is obtained by detecting the positions of the face and eyes of the user 230 using the beam splitter angle adjustment unit 1010 based on the information on the face and eyes of the user 230 captured by the imaging unit 510. If the obtained height information differs from the pre-determined viewing height, the beam splitter angle adjustment unit 1010 can drive the piston mechanism 310 to change the angle of the beam splitter 101 to a position optimal for viewing by the user 230.

[0129] A plurality of imaging units 510 may be provided. By using a plurality of imaging units 510, 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 user 230 on the floating-in-space image 3. The imaging unit 510 may be provided separately from the floating-in-space image display device 400. When the imaging unit 510 is provided separately from the floating-in-space image display device 400, it is sufficient to configure it so that an imaging signal can be transmitted to the floating-in-space image display device 400 via a wired or wireless communication connection path or the like.

[0130] For example, if the aerial operation detection sensor 1351 is configured as an object intrusion sensor that targets a plane (intrusion detection plane) including the display surface of the 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.

[0131] In such a case, the distance between the object and the intrusion detection plane can be calculated by using information such as object depth calculation information based on the captured images of the multiple imaging units 510 and object depth information by a depth sensor. These pieces of information and various information such as the distance between the object and the intrusion detection plane are used for various display controls of the floating in space image 3. Furthermore, without using the mid-air operation detection sensor 1351, the mid-air operation detection unit 1350 may detect a touch operation on the floating in space image 3 by the user 230 based on the captured images of the imaging unit 510.

[0132] Furthermore, the imaging unit 510 may capture an image of the face of the user 230 operating the space-floating image 3, and the control unit 1110 may perform an identification process for the user 230. Furthermore, in order to determine whether or not there is another person standing around or behind the user 230 operating the space-floating image 3 and peeking at the operation of the user 230 on the space-floating image 3, the imaging unit 510 may capture an image of the user 230 operating the space-floating image 3 and a range including the area surrounding the user 230.

[0133] 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 air operation (touch operation) by the user 230. Apart from the above-mentioned user 230 who touches the space floating image 3, the operation input unit 1107 may also be used by, for example, an administrator to operate the space floating image display device 400.

[0134] The video signal input unit 1131 is connected to an external video output device and inputs video data. The video signal input unit 1131 can be implemented using a variety of 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.

[0135] An external audio output device is connected to the audio signal input unit 1133 to input audio data. The audio signal input unit 1133 may be configured with an audio input interface conforming to the HDMI standard, an optical digital terminal interface, a coaxial digital terminal interface, or the like.

[0136] 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 the terminals and the cables are integrated.

[0137] 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. The audio output unit 1140 may also output built-in operation sounds or error warning sounds. Alternatively, the audio output unit 1140 may be configured to output a digital signal to an external device, such as the Audio Return Channel function defined in the HDMI standard.

[0138] The nonvolatile memory 1108 stores various data used by the space floating image display device 400. The data stored in the nonvolatile memory 1108 includes, for example, data for various operations to be displayed on the space floating image 3, display icons, data and layout information for objects to be operated by the user, etc. The memory 1109 stores image data to be displayed as the space floating image 3, data for controlling the device, etc.

[0139] The control unit 1110 controls the operation of each connected unit. In addition, the control unit 1110 may cooperate with a program stored in the memory 1109 to perform calculations based on information acquired from each unit in the space floating image display device 400.

[0140] 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.

[0141] 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 a floating image 3 via the liquid crystal display panel 11 and the retroreflective member 2.

[0142] 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.

[0143] The video data, image data, etc. recorded in the storage unit 1170 are output as the space floating image 3 via the liquid crystal display panel 11 and the retroreflective member 2. The video data, image data, etc. of the display icons and objects for the user to operate, etc., displayed as the space floating image 3, are also recorded in the storage unit 1170.

[0144] Layout information of display icons, objects, etc. displayed as the space floating image 3, and various metadata information related to the objects, etc. are also recorded in the storage unit 1170. The audio data recorded in the storage unit 1170 is output as audio from the audio output unit 1140, for example.

[0145] The video control unit 1160 performs various controls related to the video signal input to the liquid crystal display panel 11. The video control unit 1160 may be referred to as a video processing circuit, and may be configured with hardware such as an ASIC, an FPGA, or a video processor. The video control unit 1160 may also be referred to as a video processing unit or an image processing unit. The video control unit 1160 controls video switching, such as which video signal to input to the liquid crystal display panel 11, between the video signal stored in the memory 1109 and the video signal (video data) input to the video signal input unit 1131. The video control unit 1160 may also generate a superimposed video signal by superimposing the video signal 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 liquid crystal display panel 11, thereby controlling the formation of a composite video as the floating-in-space video 3.

[0146] The video control unit 1160 may also 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, and the like. Examples of image processing include scaling processing to enlarge, reduce, or deform 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. The video control unit 1160 may also perform special effect video processing, etc., on the video signal input to the liquid crystal display panel 11 to assist the user 230 in performing an aerial operation (touch operation). The special effect video processing is performed, for example, based on the detection result of the touch operation of the user 230 by the aerial operation detection unit 1350 and the image of the user 230 captured by the imaging unit 510.

[0147] The attitude sensor 1113 is a sensor configured with 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 400 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 is detected as the user's usage state, the control unit 1110 may perform control such that the display of the image being displayed on the liquid crystal display panel 11 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 400, the control unit 1110 may perform control such that the display direction of the image being displayed on the liquid crystal display panel 11 is rotated.

[0148] As explained above, various functions are installed in the space floating image display device 400. However, the space floating image display device 400 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.

[0149] [Fifth Example] The space floating image display devices of the respective embodiments shown in FIGS. 11 to 13 have a basic configuration that corresponds to the Z-type configuration shown in FIG.

[0150] FIG. 11 shows an example of the configuration of a space floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as a fifth embodiment).

[0151] FIG. 11 shows a cross-sectional view (A) of the space-floating image display device as seen from the side, and a top view (B) of the device as seen from the front. The front of the device here is the surface corresponding to the direction in which a user can view the space-floating image 3D formed by the space-floating image display device 400 from the front. Direction D is the direction in which a user views the space-floating image 3D from the front, and corresponds to the negative direction of the Z direction. For explanatory purposes, a coordinate system or direction such as the illustrated (X, Y, Z) may be used. The Z direction is the vertical direction, or up-down direction, while the X and Y directions are two orthogonal horizontal directions, the X direction is the depth direction, or front-to-back direction (the horizontal front-to-back direction within the screen of the space-floating image 3D), and the Y direction is the left-to-right direction (the horizontal left-to-right direction within the screen of the space-floating image 3D).

[0152] The Z-shaped configuration of Fig. 11 has the same positional relationship of the components (image display device 1, beam splitter 101D, retroreflective member 2A, etc.) as the Z-shaped configuration of Fig. 3. In order to form a space-floating image 3D, the components of the space-floating image display device (image display device 1, beam splitter 101D, retroreflective member 2, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101D, retroreflective member 2A, etc. of the image display device unit 300 of Fig. 11 are arranged with a predetermined positional relationship so as to form a Z shape, similar to the configuration of Fig. 3.

[0153] The space-floating image display device of the fifth embodiment shown in FIG. 11 is roughly composed of an image display device unit 300, a housing 106 corresponding to the image display device unit 300, a space-floating image display device 400, a housing 4001 having an opening 4002 corresponding to the space-floating image display device 400, and a hinge mechanism 332 that serves as a rotation fulcrum at one end of the beam splitter 101D.

[0154] Hinge mechanism 332 is provided on housing 4001, rotatably holds beam splitter 101D on one side of beam splitter 101D opposite user 230, and serves as a rotation fulcrum for beam splitter 101D.

[0155] The image display device 1 is mounted and housed in a housing portion of a housing 106. In Fig. 11, if the XY plane shown in the figure is the desk surface (a horizontal plane in this example), the housing 106 is placed along an XZ plane perpendicular to the desk surface.

[0156] The housing 106 is roughly rectangular and flat with a predetermined height (predetermined thickness in the Y direction). Inside the housing 106, the image display device 1 is placed along the XZ plane on the desk surface. The space-floating image display device 400 is placed opposite the housing 106 in the Y direction.

[0157] The space-floating image display device 400 is mounted and housed in a housing 4001. The space-floating image display device 400 is made up of a retroreflection member 2A, a λ / 4 plate 21A, a beam splitter 101D, and the like.

[0158] In this embodiment, a transparent member 100 such as a glass plate and an absorptive polarizing plate 112 are provided to reduce the effect of external light incident through the opening 4002 on the retroreflective member 2A and the image display device 1. The direction D is the direction from top to bottom in the Z direction, which is the vertical direction in this embodiment, and is perpendicular to the opening 4002.

[0159] In this embodiment, beam splitter 101D is disposed at an angle to the desk surface inside housing 4001. "At an angle" refers to the angle that the direction of one side of the main surface of beam splitter 101D makes with the Y direction of the desk surface (XY plane), and for example, in FIG. 11, angle α, which is the angle of the angle, is about 45 degrees (≈45°).

[0160] A retroreflective member 2A and a λ / 4 plate 21A are arranged on the opposite side of the image display device 1 (FIG. 11) in the Y direction across the beam splitter 101D. The λ / 4 plate 21A is arranged on the side of the main surface of the retroreflective member 2A where the beam splitter 101D is arranged. In other words, the λ / 4 plate 21A is arranged on the light incident side of the retroreflective member 2A. The space-floating image 3D (shown in a dashed-line frame) is arranged between the housing 106 and the retroreflective member 2A, extending upward in the Z direction from the beam splitter 101D and in the horizontal direction (XY plane). The space-floating image 3D is an aerial image formed corresponding to the beam splitter 101D.

[0161] In this embodiment, the components of the image display device 1, ie, the light source device 13, the liquid crystal display panel 11, the absorptive polarizer 12, etc., are housed and fixed in a housing 106.

[0162] An opening 1061 is provided on the left surface of housing 106 in the Y direction and on the right surface of housing 4001 in the Y direction. Opening 1061 is a portion through which image light from image display device 1 passes or is transmitted. A transparent member or the like may be provided in opening 1061. Image display device 1, more specifically, image light corresponding to an image displayed on liquid crystal display panel 11, passes through opening 1061 and travels toward beam splitter 101D, which is located in the left direction (negative direction) in the Y direction.

[0163] As with the configuration described above (Figure 3), beam splitter 101D transmits P-polarized light and reflects S-polarized light, and can be formed, for example, by depositing an optical thin film on a flat glass substrate. In this case, the incident angle of polarized light to beam splitter 101D is approximately 45 degrees ±15 degrees, generating a 3D floating image positioned horizontally (on the XY plane).

[0164] In FIG. 11, dashed arrows indicate image light emitted from the image display device 1 through the opening 1061 in the negative Y direction along optical axis D1. This is shown as a representative example of four dashed arrows for the beam splitter 101D. The image light emitted from the liquid crystal display panel 11 is assumed to have a predetermined polarization characteristic, for example, P polarization (parallel polarization: P stands for parallel). This P-polarized image light passes through the beam splitter 101D on optical axis D1 in the negative Y direction (left) and travels toward the retroreflective member 2A on optical axis D2 corresponding to optical axis D1. The beam splitter 101D has the property of passing P-polarized light and reflecting S-polarized light (vertical polarization: S stands for Senkrecht). The beam splitter 101D is positioned so as to form an angle of, for example, approximately 45 degrees with the P-polarized image light (optical axis D2, Y direction). In other words, the beam splitter 101D is disposed so that its main surface forms an angle of approximately 45 degrees with respect to the Z direction that forms the main surfaces of the liquid crystal display panel 11 and the retroreflective member 2A.

[0165] A λ / 4 plate 21A is provided on the light incident surface of the retroreflective member 2A. The P-polarized image light with optical axis D1 emitted from the image display device 1 and transmitted through the beam splitter 101D passes through the λ / 4 plate 21A twice, once before and once after being reflected by the retroreflective member 2A, thereby being converted from P-polarized light to S-polarized light. As a result, the S-polarized image light that travels on optical axis D2 after being reflected by the retroreflective member 2A is reflected by the beam splitter 101D and travels on optical axis D3 in the Z direction. As shown in the figure, this S-polarized image light generates and displays a real, space-floating 3D image at a predetermined position in the Z direction after passing outside the opening 4002, the transparent member 100, and the absorptive polarizer 112.

[0166] The predetermined position where the floating image 3D is formed is determined according to the optical distance of the optical path of the optical system including the image display device 1, the beam splitter 101D, and the retroreflective member 2A. The distance between the floating image 3D and the beam splitter 101D is approximately equal to the distance between the image display device 1 and the beam splitter 101D.

[0167] 11 is a mechanism that does not move up, down, left, or right, but is freely rotatable. The hinge mechanism 332 is provided in the X direction at the left end of the beam splitter 101D, and the beam splitter 101D rotates up and down around the hinge mechanism 332 as a rotation fulcrum. That is, the beam splitter 101D can be positioned at a different angle relative to the image display device 1 and the retroreflective member 2A, while the image display device 1 and the retroreflective member 2A are fixedly positioned. Alternatively, the beam splitter 101D can be rotated around the hinge mechanism 330 as a rotation fulcrum, thereby changing the separation distance between the beam splitter 101D and the image display device 1, and between the beam splitter 101D and the retroreflective member 2A. Even if the positioning angle of the beam splitter 101D is different, the beam splitter 101D is positioned in a Z-shape similar to the configuration of FIG. 3.

[0168] In the space-floating image display device of the fifth embodiment shown in FIG. 11 , consider the case where beam splitter 101D is rotated upward by angle γ relative to the horizontal position (XY plane) around hinge mechanism 332 as a rotation fulcrum to move to the position of beam splitter 101E. In this configuration, P-polarized image light from image display device 1 travels along optical axis D1, transmits through beam splitter 101E, and passes through λ / 4 plate 21A twice, once before and after reflection by retroreflective member 2A, thereby being converted from P-polarized to S-polarized light. As a result, the S-polarized image light traveling along optical axis D2 after reflection by retroreflective member 2A is reflected by beam splitter 101E and travels along optical axis E3 in the Z direction. As shown in the figure, this S-polarized image light generates and displays a space-floating image 3E, which is a real image, at a predetermined position in the Z direction after passing outside opening 4002, transparent member 100, and absorptive polarizer 112.

[0169] The predetermined position where the floating image 3E is formed is determined according to the optical distance of the optical path of the optical system including the image display device 1, the beam splitter 101E, and the retroreflective member 2A. The distance between the floating image 3E and the beam splitter 101E is approximately equal to the distance between the image display device 1 and the beam splitter 101E.

[0170] By rotating the beam splitter 101E upward by an angle γ with respect to the horizontal position (XY plane) around the hinge mechanism 332 as a rotation fulcrum, the distance between the image display device 1 and the beam splitter 101E becomes farther on the surface of the beam splitter 101E that is farther from the hinge mechanism 332 than on the surface of the beam splitter 101D. As a result, the floating-in-space image 3E of the beam splitter 101E is generated and displayed at a position rotated upward by an angle γ with respect to the floating-in-space image 3D of the beam splitter 101D, which is in a nearly horizontal position. The formed floating-in-space image 3E can be viewed as a bright image by the user 230E positioned directly in front of the beam splitter 101E from the direction E indicated by the arrow. In other words, by changing the tilt angle γ of the beam splitter 101D around the hinge mechanism 332 as a rotation fulcrum, the floating-in-space image 3D can be generated and displayed at a position tilted from the horizontal position.

[0171] The imaging unit 510 is a camera with an image sensor, and captures the faces, eyes, arms, fingers, and / or the space of the floating in space images 3D and 3E of the users 230D and 230E. For example, from the information on the faces and eyes of the users 230D and 230E captured by the imaging unit 510, the beam splitter angle adjustment unit 1010 (FIG. 10) detects the positions of the faces and eyes of the users 230D and 230E, and drives the hinge mechanism 332 to adjust the angle of the beam splitter 101D from the angle optimal for the visibility of the user 230D to the angle optimal for the visibility of the user 230E.

[0172] [Sixth Example] FIG. 12 shows an example of the configuration of a space floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as a sixth embodiment).

[0173] The embodiment of FIG. 12 is an arrangement in which the space-floating image display device of the embodiment of FIG. 11 is rotated 90° to the left around the X axis. In this embodiment, the coordinate system has the Y direction as the vertical direction, the up-down direction, the Z direction and the Y direction as two orthogonal horizontal directions, the X direction as the depth direction, the front-to-back direction, and the Z direction as the left-to-right direction. In other words, the coordinate relationship as seen from the space-floating image display device is the same in the embodiment of FIG. 11 and the embodiment of FIG. 12. The front of the device here is the plane (YX plane) corresponding to the direction in which a user can view the space-floating image 3D formed by the space-floating image display device 400 from the front. Direction D is the direction in which a user views the space-floating image 3D from the front, and corresponds to the negative direction in the Z direction.

[0174] In the embodiment of FIG. 12, the space-floating image display device 400 has the same components as the embodiment of FIG. 11, and the same reference numerals are used. The space-floating image 3D and the space-floating image 3E are generated and displayed by the same means. The viewpoint positions of user 230D and user 230E in the embodiment of FIG. 12 are in the same positional relationship as in the embodiment of FIG. 11, but it is assumed that user 230D is taller than user 230E. User 230D is best suited to space-floating image 3D facing forward. Because user 230E is shorter than user 230D, he will look up slightly at the space-floating image display device 400, and the space-floating image 3E will be facing forward, making it the optimal viewing position.

[0175] The imaging unit 510 is a camera with an image sensor, and captures the height, face, eyes, and / or the space floating image 3D of the users 230D and 230E, and the space around the space floating image 3E. For example, for user 230D, the beam splitter angle adjustment unit 1010 (FIG. 10) detects the eye position of user 230D from the height, face, and eye position information of user 230D captured by the imaging unit 510, and adjusts and places the angle of the beam splitter 101 to the position of beam splitter 101D using the hinge mechanism 332. This allows user 230D to view the space floating image 3D at the optimal position in the front direction.

[0176] For short user 230E, the beam splitter angle adjustment unit 1010 (Fig. 10) detects the eye position of user 230E from the height of user 230E captured by imaging unit 510 and the position information of the face and eyes, and adjusts and places the angle of beam splitter 101D to the position of beam splitter 101E by rotating it clockwise by rotation angle γ using hinge mechanism 332. This allows user 230E to view the floating image 3E in space at the optimal position in the front direction, looking up slightly.

[0177] This embodiment is effective not only for users shorter than the user 230D, but also for users taller than the user 230D. By adjusting the angle of the beam splitter 101D clockwise based on, for example, eye position information of a user taller than the user 230D captured by the imaging unit 510, it is possible to adjust the tilt angle of the generated floating-in-space image so that it is optimally visible to users taller than the user 230D. This improves the visibility of the user (observer), and is suitable for improving operability.

[0178] [Seventh Example] FIG. 13 shows an example of the configuration of a space floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as a seventh embodiment).

[0179] 13(A) is a cross-sectional view of the appearance of a space-floating image display device according to one embodiment (seventh embodiment) when viewed from the side, and FIG. 13(B) is a cross-sectional view of the appearance of a space-floating image display device according to one embodiment (seventh embodiment) when viewed from above. In FIG. 13(B), the retroreflective member 2B is arranged to face the liquid crystal display panel 11 at a predetermined angle. The front of the device here corresponds to the surface from which a user can view the space-floating image 3F formed by the space-floating image display device 400 from the front. Direction F is the direction from which a user 230F views the space-floating image 3F from the front, and corresponds to the negative direction in the Z direction.

[0180] The Z-shaped configuration in FIG. 13 is similar to the Z-shaped configuration in FIG. 3 in terms of the relative positions of the components (image display device 1, beam splitter 101F, retroreflective member 2B, etc.).

[0181] In order to form the space-floating image 3F, the components of the space-floating image display device (image display device 1, beam splitter 101F, retroreflective member 2B, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101F, retroreflective member 2B, etc. of the image display device unit 300 in Fig. 13 are arranged with a predetermined positional relationship so as to form a Z-shape, similar to the configuration in Fig. 3.

[0182] The seventh embodiment of the floating image display device shown in FIG. 13 is roughly comprised of an image display device unit 300, a housing 106 corresponding to the image display device unit 300, a floating image display device 400, a housing 4001 having an opening 4002 corresponding to the floating image display device 400, and a hinge mechanism 333 for rotatably holding the beam splitter 101F.

[0183] The hinge mechanism 333 rotatably holds both ends of the beam splitter 101F at or near the center line of the beam splitter 101F, which is parallel to the side of the beam splitter 101F facing the user 230, and serves as a rotation fulcrum for the beam splitter 101F. The hinge mechanism 333 does not move up, down, left, or right, but is free to rotate, and the beam splitter 101F is structured to rotate up and down around the hinge mechanism 333 as a rotation fulcrum. In other words, the beam splitter 101F can be positioned at a different angle relative to the image display device 1 and the retroreflective member 2B, which are fixed in position. Alternatively, the beam splitter 101F can be rotated around the hinge mechanism 333 as a rotation fulcrum, and the separation distance between the beam splitter 101F and the image display device 1, and between the beam splitter 101F and the retroreflective member 2B, can be changed. Even if the angle at which beam splitter 101F is disposed is different, it is disposed with a positional relationship so as to form a Z-shape similar to the configuration in FIG.

[0184] P-polarized image light emitted from the image display device 1 passes through the beam splitter 101F and reaches the λ / 4 plate 21B. After passing through the λ / 4 plate 21B, the image light is reflected by the retroreflective member 2B and passes through the λ / 4 plate 21B a total of two times, resulting in polarization conversion from P-polarized light to S-polarized light. The image light is reflected by the beam splitter 101F and generates a space-floating image 3F in the Z-axis direction, i.e., the vertical direction.

[0185] 13(B) schematically shows unwanted light 600 with a white arrow. Of the P-polarized image light that becomes unwanted light 600, a portion of the P-polarized image light that reaches λ / 4 plate 21B is specularly reflected by the surface of λ / 4 plate 21B and proceeds to beam splitter 101F as P-polarized light. Furthermore, a portion of the P-polarized image light is also specularly reflected by the surface of beam splitter 101F.

[0186] In this embodiment, the retroreflective member 2B and the λ / 4 plate 21B are not parallel to the XZ plane, but are arranged at an angle on the XY plane. Therefore, the P-polarized image light, which becomes unwanted light 600, is specularly reflected from the surface of the λ / 4 plate 21B parallel to the incident light in the YZ plane. However, because the λ / 4 plate 21B is angled relative to the XY plane, it is specularly reflected at an angle corresponding to the incident angle and is incident on the surface of the beam splitter 101F at an angle on the XY plane. Therefore, the unwanted light 600 is specularly reflected from the surface of the beam splitter 101F at an angle corresponding to the incident angle, but deviates from the Z direction (directly above) and travels in a direction outside the screen of the floating-in-space image 3F. As a result, when a user views the floating-in-space image 3F from direction F, the unwanted light 600 is outside the screen of the floating-in-space image 3F and is not visible, thereby preventing the unwanted light 600 from interfering with the visibility of the floating-in-space image.

[0187] In the first embodiment of the floating image display device shown in FIG. 13, the beam splitter 101F is rotated counterclockwise or upward by an angle γ with respect to the horizontal position (XY plane) using the hinge mechanism 333 provided at or near the center line of the beam splitter 101F as the rotation fulcrum, and is positioned at the position of the beam splitter 101J.

[0188] In this arrangement, consider image light from a position away from the center of image display device 1. Image light with optical axis F1 at the lower end of image display device 1 is transmitted by beam splitter 101F, passes through λ / 4 plate 21B along optical axis F1, and enters retroreflective member 2B. The image light retroreflected by retroreflective member 2B passes through λ / 4 plate 21B again and is converted into the other polarized wave, and the image light reflected by beam splitter 101F generates a real image, a floating-in-space image 3F, at a predetermined position outside transparent member 100 in the direction of optical axis F3 corresponding to optical axis F2.

[0189] Next, when beam splitter 101F rotates by angle γ and reaches the position of beam splitter 101J, the image light of image display device 1 with optical axis F1 passes through beam splitter 101J, passes through λ / 4 plate 21B along optical axis F2, and enters retroreflective member 2B. The image light retroreflected by retroreflective member 2B passes through λ / 4 plate 21B again and is converted into the other polarized wave, reflected by beam splitter 101J, and generates space-floating image 3J, which is a real image, at a predetermined position outside transparent member 100 in the direction of optical axis J3.

[0190] Due to the rotation of the angle γ, the distance between the bottom end of the image display device 1 and the beam splitter 101J becomes shorter than that of the beam splitter 101F, in other words, the optical path distance becomes shorter, so that the left end position of the generated floating-in-space image 3J becomes lower than the left end position of the floating-in-space image 3F.

[0191] Conversely, due to the rotation of angle γ, the distance between the top of image display device 1 and beam splitter 101J becomes farther than that of beam splitter 101F. In other words, the optical path distance becomes longer, so the right edge position of generated floating-in-space image 3J becomes higher than the right edge position of floating-in-space image 3F. In other words, floating-in-space image 3J is tilted counterclockwise more than floating-in-space image 3F. In other words, by changing the tilt angle γ of beam splitter 101F with hinge mechanism 333 as the rotation fulcrum, floating-in-space image 3F can be generated and displayed at a position tilted from the horizontal position.

[0192] The imaging unit 510 is a camera with an image sensor, and captures the faces, eyes, arms, and fingers of the users 230F and 230J and / or the space of the floating images in space 3F and 3J. For example, the information on the faces and eyes of the users 230F and 230J captured by the imaging unit 510 can be used by the beam splitter angle adjustment unit 1010 (FIG. 10) to detect the positions of the faces and eyes of the users 230F and 230J, and drive the hinge mechanism 333 to adjust the angle of the beam splitter 101F, for example, from the optimal viewing position for the user 230F to an angle of the beam splitter 101J suitable for viewing by the user 230J.

[0193] As described above, the floating image display device shown in Figures 7 to 9 comprises a display panel that displays an image, a polarization separation member that reflects a portion of the image light emitted from the display panel, and a retroreflective member that retroreflects the reflected light from the polarization separation member, and the reflected light retroreflected by the retroreflective member passes through the polarization separation member to form a floating image, and the angle of the polarization separation member relative to the display panel and the retroreflective member is variable.

[0194] As described above, the floating image display device shown in Figures 11 to 13 also comprises a display panel that displays an image, a polarization separation member that transmits a portion of the image light emitted from the display panel, and a retroreflective member that retroreflects the light that has transmitted through the polarization separation member, and the reflected light retroreflected by the retroreflective member is reflected back onto the polarization separation member to form the floating image, and the angle of the polarization separation member relative to the display panel and the retroreflective member is variable.

[0195] As described above, the space-floating image display device of each embodiment and modification is suitable for use mainly indoors and can display space-floating images with high visibility. Furthermore, the space-floating image display device of this embodiment is configured to display the spatial image at different heights and inclinations, improving visibility and operability. More specifically, a function is provided to adjust the angle of the beam splitter relative to the bottom surface, etc., so that space-floating images with different heights and inclinations are displayed from each beam splitter.

[0196] This has the effect of improving the visibility and operability of the floating image for users of different viewing positions and heights. When the generated floating image is used as a non-contact user interface, it is easier for users to use, has higher visibility and operability, and prevents or reduces operational errors and input errors.

[0197] This embodiment may be installed on a desk, for example. The λ / 4 plate 21B may be located in any position between the beam splitter 101 and the opening 4002 as long as it is located before the image of the floating image is formed. The retroreflective member 2 may be located so as to face the liquid crystal display panel 11 at a predetermined angle.

[0198] Due to the above effects, the space-floating image display device of each embodiment and modified example can display bright, highly visible space-floating images without emitting unnecessary image light to people other than the user, even when used in a relatively small room, and because it is small and lightweight, it is suitable for easy installation on a desk, table, shelf, etc. indoors.

[0199] Although the embodiments of the present disclosure have been specifically described above, they are not limited to the above-described embodiments and various modifications are possible without departing from the spirit of the present disclosure. Unless otherwise specified, each component may be singular or plural. Components of each embodiment may be added, deleted, or replaced, except for essential components. Furthermore, combinations of each embodiment are also possible.

[0200] For example, the beam splitter may be a curved beam splitter instead of a flat plate. Also, in the above-mentioned embodiment, the user mainly views the floating image in the vertical direction, but of course it is not limited to this. If the arrangement of the floating image display device of each embodiment is rotated as a whole, it is possible to display the floating image in a direction different from the above-mentioned example. Also, the image display device 1 may be called a display panel, a liquid crystal display panel, a liquid crystal panel, etc.

[0201] [Eighth Example] The space floating image display devices of the respective embodiments shown in FIGS. 14 and 15A to 15F correspond to the Z-type configuration shown in FIG. 3 as a basic configuration.

[0202] 14 is a perspective view showing an example of the shape of a beam splitter (polarization separation member) that transmits a portion of the image light emitted from the display panel of a space-floating image display device suitable for installation on a desk, according to one embodiment (referred to as the eighth embodiment). (A) is a flat beam splitter, corresponding to beam splitters 101D, 101J, etc. of the space-floating image display devices shown in FIGS. 11 to 13. In contrast, (B), (C), and (D) show examples of beam splitters that are curved rather than flat, with the height of the inside of the beam splitter different from the surrounding edges. Beam splitter 101K in (B) is a semi-cylindrical plate material surrounded by a pair of straight edges A1, A1′ and a pair of curved edges B1, B1′. Beam splitter 101L in (C) is a semi-cylindrical plate material obtained by rotating beam splitter 101K in (B) by 90 degrees, and is surrounded by a pair of straight sides A2, A2' and a pair of curved sides B2, B2'. Note that curved sides B1, B1', B2, B2' of beam splitters 101K and 101L are not limited to being portions of a circle or ellipse, but may be curved lines or polygonal approximations of any curvature. Beam splitter 101P in (D) is a conical or lens-shaped plate material, with bottom peripheral portion B3 surrounded by a circle or curve, and the sides slope upward toward the apex of the plate material. Bottom peripheral portion B3 is not limited to being portions of a circle or ellipse, but may be curved lines or polygonal approximations of any curvature.

[0203] 15A shows an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (referred to as the eighth embodiment). In FIG. 15A, a YZ cross-sectional view (A) of the space-floating image display device when viewed from the side, an XY top view (B) and an XZ cross-sectional view (C) when viewed from the front of the device are shown. The front of the device here is the surface corresponding to the direction in which a user can view the space-floating image 3K formed by the space-floating image display device 400 from the front. Direction K is the direction in which a user 230K views the space-floating image 3K from the front, and corresponds to the negative direction in the Z direction. For the sake of explanation, a coordinate system and directions such as the (X, Y, Z) shown in the figure may be used. The Z direction is the vertical direction, the up-down direction, the X direction and the Y direction are two horizontal directions that intersect at right angles, the X direction is the depth direction, the front-to-back direction (the horizontal front-to-back direction within the screen of the floating image K), and the Y direction is the left-to-right direction (the horizontal left-to-right direction within the screen of the floating image 3K).

[0204] The Z-shaped configuration of Fig. 15A has the same positional relationship of the components (image display device 1, beam splitter 101K, retroreflective member 2A, etc.) as the Z-shaped configuration of Fig. 3. In order to form the space-floating image 3K, the components of the space-floating image display device 400 (image display device 1, beam splitter 101K, retroreflective member 2A, etc.) are mutually arranged with a predetermined positional relationship. That is, the image display device 1, beam splitter 101K, retroreflective member 2A, etc. of the image display device unit 300 of Fig. 15A are arranged with a predetermined positional relationship so as to form a Z-shape, similar to the configuration of Fig. 3.

[0205] The space-floating image display device 400 is mounted and housed in a housing 4001. The space-floating image display device 400 is made up of a retroreflection member 2A, a λ / 4 plate 21A, a beam splitter 101K, and the like.

[0206] In this embodiment, a transparent member 100 such as a glass plate and an absorptive polarizing plate 112 are provided to reduce the effect of external light incident through the opening 4002 on the retroreflective member 2A and the image display device 1. The direction K is the Z direction, which is the vertical direction in this embodiment, from top to bottom, and is perpendicular to the opening 4002.

[0207] In this embodiment, the beam splitter 101K is a semi-cylindrical plate material as shown in FIG. 14B and is surrounded by a pair of straight sides and a pair of curved sides. Within the housing 4001, the beam splitter 101K is disposed at an angle with respect to the desk surface. The oblique angle means that one straight side (e.g., A1) of the beam splitter 101K is disposed near the image display device 1, and the other straight side (e.g., A1') of the beam splitter 101K is disposed near the retroreflective member 2A. The angle formed by the direction of a line segment connecting both ends of the arc of the curved side surface of the beam splitter 101K corresponds to the Y direction of the desk surface (XY plane). For example, in FIG. 15A, the oblique angle α is approximately 45 degrees (≒45°).

[0208] A retroreflective member 2A and a λ / 4 plate 21A are arranged on the opposite side of the image display device 1 in the Y direction across the beam splitter 101K. The λ / 4 plate 21A is arranged on the side of the main surface of the retroreflective member 2A where the beam splitter 101K is arranged. In other words, the λ / 4 plate 21A is arranged on the light incident side of the retroreflective member 2A. The space-floating image 3K (shown in a dashed line frame) is arranged between the housing 106 and the retroreflective member 2A, extending upward in the Z direction from the beam splitter 101K and in the horizontal direction (XY plane). The space-floating image 3K is an aerial image formed in correspondence with the beam splitter 101K. The space-floating image 3K is also an aerial image with a curved surface corresponding to the shape of the beam splitter 101K.

[0209] An opening 1061 is provided on the left surface of the housing 106 in the Y direction and on the right surface of the housing 4001 in the Y direction. The opening 1061 is a portion through which the image light from the image display device 1 passes or is transmitted. A transparent member or the like may be provided in the opening 1061. The image light corresponding to the image displayed on the image display device 1, more specifically, on the liquid crystal display panel 11, passes through this opening 1061 and travels toward the beam splitter 101K located in the left direction (negative direction) in the Y direction.

[0210] As with the configuration described above (Figure 3), beam splitter 101K has the property of transmitting P-polarized light and reflecting S-polarized light. For example, it can be formed by depositing an optical thin film on a curved glass or resin substrate. In this case, the angle of incidence of polarized light on beam splitter 101K changes depending on the angle of the curved surface, centered around approximately 45 degrees, and a floating image 3K in space is generated, positioned almost horizontally (on the XY plane).

[0211] In FIG. 15A, an example of image light emitted from the image display device 1 through the opening 1061 in the negative Y direction is indicated by a dashed arrow, and the dashed arrow of the optical axis K1 is used as a representative example. The image light emitted from the liquid crystal display panel 11 is assumed to have a predetermined polarization characteristic, for example, P polarization (parallel polarization: P stands for parallel). This P-polarized image light passes through the beam splitter 101K on the optical axis K1 in the negative Y direction (left) and travels toward the retroreflective member 2A on the optical axis K2 corresponding to the optical axis K1. The beam splitter 101K has the property of passing P-polarized light and reflecting S-polarized light (vertical polarization: S stands for Senkrecht). As shown in the figure, the curved surface of the beam splitter 101K that transmits P-polarized light on the optical axis K1 forms an angle greater than the aforementioned angle α of approximately 45 degrees.

[0212] A λ / 4 plate 21A is provided on the light incident surface of the retroreflective member 2A. The P-polarized image light with optical axis K1 that is emitted from the image display device 1 and transmitted through the beam splitter 101K passes through the λ / 4 plate 21A twice, once before and once after being reflected by the retroreflective member 2A, and is thereby converted from P-polarized light to S-polarized light. As a result, the S-polarized image light that has traveled on optical axis K2 after being reflected by the retroreflective member 2A is reflected by the beam splitter 101K and travels on optical axis K3 in the Z direction. Because the angle of incidence of optical axis K2 with respect to the curved reflective surface of beam splitter 101K is smaller than the approximately 45 degrees mentioned above, this S-polarized image light travels in a direction slightly tilted in the -Y direction from the Z direction directly above (approximately 90 degrees) as shown, and passes through the outside of opening 4002, transparent member 100, and absorptive polarizer 112, generating and displaying space-floating image 3K, which is a real image, at a predetermined position in the Z direction. Other image light indicated by dashed arrows that is emitted in the negative Y direction also behaves in the same way as the optical axes K1 and K2 mentioned above, but the angle of incidence of the S-polarized image light reflected by the curved reflective surface of beam splitter 101K, corresponding to optical axis K2, differs depending on the reflection position on the surface of beam splitter 101K. Therefore, the S-polarized reflected image light travels in the Z direction, but as shown in the example of Figure 15A(A), depending on the reflection position on the surface of the beam splitter 101K, it travels in a direction tilted from the -Y direction to +Y direction from the Z direction directly above (approximately 90 degrees), and a real image, a floating image 3K in space, is generated and displayed at a predetermined position in the Z direction.

[0213] The predetermined position where the floating image 3K is formed is determined by the optical path distance of the optical system including the image display device 1, the beam splitter 101K, and the retroreflective member 2A. The distance between the floating image 3K and the beam splitter 101K is approximately equal to the distance between the image display device 1 and the beam splitter 101K. Because the beam splitter 101K has the semi-cylindrical shape shown in FIG. 14(B), the floating image 3K also has an approximately semi-cylindrical shape. In other words, the shape is an extension of the circular curve of the YZ cross section in the -X direction. Therefore, when viewed from the direction K, the user 230K can see the floating image 3K, with the center part along the X axis rising convexly in the direction of travel of the light forming the floating image.

[0214] Fig. 15B is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (eighth embodiment). Fig. 15B is configured by replacing the beam splitter 101K in the space-floating image display device 400 of the embodiment of Fig. 15A with a beam splitter 101M. Fig. 15B(A) shows a YZ cross-sectional view, and Fig. 15B(B) shows the configuration of the beam splitter 101M. In this embodiment, differences from the embodiment of Fig. 15A will be explained, and repeated explanations of the same configuration as Fig. 15A will be omitted.

[0215] Beam splitter 101M is a semi-cylindrical plate material of beam splitter 101K in Fig. 14(B) that is surrounded by the pair of straight sides A1, A1' and the pair of curved sides B1, B1', and curved sides B1, B1' are configured with polygonal approximate curves BM1 and BM1'. In this embodiment, multiple small rectangular beam splitter pieces are arranged in a staircase pattern to configure the staircase approximate curves BM1 and BM1' parallel to the bottom surface of beam splitter 101M and the corresponding approximate curved surfaces.

[0216] In this embodiment, the beam splitter 101M is disposed obliquely with respect to the desk surface within the housing 4001. One straight side (e.g., A1) of the beam splitter 101M is disposed near the image display device 1, and the other straight side (e.g., A1') of the beam splitter 101M is disposed near the retroreflective member 2A. The angle formed by the direction of the line segment connecting both ends of the arc of the approximate curved side surface of the beam splitter 101M corresponds to the Y direction of the desk surface (XY plane). For example, in FIG. 15B, the oblique angle α is approximately 45 degrees (≒45°). In this embodiment, the stepped beam splitter pieces are disposed parallel to the bottom surface of the beam splitter 101M, so the angle of each beam splitter piece is the same as the angle α, which is approximately 45 degrees (≒45°).

[0217] In FIG. 15B(A), an example of image light emitted from the image display device 1 in the negative Y direction is shown by a dashed arrow, and the dashed arrow of optical axis M1 is used as a representative example for explanation. The image light emitted from the liquid crystal display panel 11 is assumed to have a predetermined polarization characteristic, for example, P polarization. This P-polarized image light passes through the beam splitter 101M on optical axis M1 in the negative Y direction (left) and travels toward the retroreflective member 2A on optical axis M2 corresponding to optical axis M1. The beam splitter 101M has the property of passing P-polarized light and reflecting S-polarized light. The rectangular beam splitter piece of the beam splitter 101M that transmits P-polarized light on this optical axis M1 has the aforementioned angle α approximately 45 degrees.

[0218] The P-polarized image light of optical axis M1 that has passed through beam splitter 101M is converted from P-polarized to S-polarized light by passing through retroreflective member 2A and λ / 4 plate 21A. As a result, the S-polarized image light that has traveled on optical axis M2 after being reflected by retroreflective member 2 is reflected by beam splitter 101M and travels on optical axis M3 in the Z direction. Because the angle of incidence of optical axis M2 with respect to the reflective surface of beam splitter 101M is approximately 45 degrees as described above, this S-polarized image light travels in the Z direction directly upward (approximately 90 degrees) as shown, passes through the outside of opening 4002, transparent member 100, and absorptive polarizing plate 112, and generates and displays space-floating image 3M, which is a real image, at a predetermined position in the Z direction. The S-polarized reflected image light from the other image light indicated by the dashed arrows emitted in the negative direction in the Y direction also travels in the Z direction, and generates and displays a real image, a floating image 3M, at a predetermined position in the Z direction, as shown in the example of Figure 15B(A).

[0219] The predetermined position where the floating image 3M is formed is determined by the optical path distance of the optical system including the image display device 1, the beam splitter 101M, and the retroreflective member 2A. The distance between the floating image 3M and the beam splitter 101M is approximately equal to the distance between the image display device 1 and the beam splitter 101M. Because the beam splitter 101M has an approximate semi-cylindrical shape as shown in FIG. 15B(B), the floating image 3M also has an approximate semi-cylindrical shape. In other words, it has a shape that is an extension of a stepped circular curve in the YZ cross section in the -X direction. Therefore, when viewed from the direction M, the user 230M can see the floating image 3M, with the center part along the X axis rising convexly in the direction of travel of the light that forms the floating image.

[0220] FIG. 15C is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to an eighth embodiment. FIG. 15C shows a configuration in which the beam splitter 101K in the space-floating image display device 400 of the embodiment of FIG. 15A is replaced with a beam splitter 101L. FIG. 15C(A) shows a YZ cross-sectional view, FIG. 15C(B) shows an XY top view, and FIG. 15C(C) shows an XZ cross-sectional view. As previously described in FIG. 14(C), the beam splitter 101L is a semi-cylindrical plate obtained by rotating the beam splitter 101K of FIG. 14(B) by 90 degrees, and is surrounded by a pair of straight sides A2, A2′ and a pair of curved sides B2, B2′. In this embodiment, differences from the embodiment of FIG. 15A are explained, and repeated explanations of the same configuration as in FIG. 15A are omitted.

[0221] In this embodiment, the beam splitter 101L is a semi-cylindrical plate material as shown in FIG. 14C and is surrounded by a pair of straight sides and a pair of curved sides. Within the housing 4001, the beam splitter 101L is disposed at an angle with respect to the desk surface. The angle means that one curved side (e.g., B2) of the beam splitter 101L is disposed near the image display device 1, and the other curved side (e.g., B2') of the beam splitter 101L is disposed near the retroreflective member 2A. The angle formed by the directions of the straight sides A2 and A2' of the beam splitter 101L corresponds to the Y direction of the desk surface (XY plane). For example, in FIG. 15C, the angle α, which is the angle of the angle, is approximately 45 degrees (≒45°). In this embodiment, the cylindrical surface sandwiched between the pair of curved sides B2 and B2' is parallel to the straight sides A2 and A2', and therefore the oblique angle is also about 45 degrees (≈45°).

[0222] The P-polarized image light of optical axis L1 that has been transmitted through beam splitter 101L is converted from P-polarized to S-polarized light by passing through retroreflective member 2A and λ / 4 plate 21A. As a result, the S-polarized image light that has been reflected by retroreflective member 2A and travels on optical axis L2 is reflected by beam splitter 101L and travels on optical axis L3 in the Z direction.

[0223] Because the angle of incidence of optical axis L2 with respect to the reflecting surface of beam splitter 101L is approximately 45 degrees as mentioned above, this S-polarized image light travels in the Z direction directly upward (approximately 90 degrees) as shown, passes through the outside of opening 4002, transparent member 100, and absorptive polarizer 112, and generates and displays space-floating image 3L, which is a real image, at a predetermined position in the Z direction. Other S-polarized reflected image light from image light indicated by dashed arrows that is emitted in the negative Y direction also travels in the Z direction, and generates and displays space-floating image 3L, which is a real image, at a predetermined position in the Z direction, as in the example shown in FIG. 15C(A).

[0224] The predetermined position where the floating image 3L is formed is determined by the optical path length of the optical system including the image display device 1, the beam splitter 101L, and the retroreflective member 2A. The distance between the floating image 3L and the beam splitter 101L is approximately equal to the distance between the image display device 1 and the beam splitter 101L. Because the beam splitter 101L has the semi-cylindrical shape shown in FIG. 14(C), the floating image 3L also has an approximately semi-cylindrical shape. In other words, the shape is an extension of the circular curve of the XZ cross section in the Y direction. Therefore, when viewed from the direction L, the user 230L can see the floating image 3L with a convex central portion along the Y axis in the direction of travel of the light forming the floating image.

[0225] FIG. 15D is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (eighth embodiment). FIG. 15D shows a configuration in which the beam splitter 101K in the space-floating image display device 400 of the embodiment of FIG. 15A is replaced with a beam splitter 101N. The beam splitter 101N is positioned so that one straight side of the beam splitter 101N is near the display panel 11 and the other straight side of the beam splitter 101N is near the retroreflective member 2A. FIG. 15D(A) shows a YZ cross-sectional view, FIG. 15D(B) shows an XY top view, FIG. 15D(C) shows an XZ cross-sectional view, and FIG. 15D(E) shows the configuration of the beam splitter 101N. In this embodiment, differences from the embodiment of FIG. 15A are explained, and repeated explanations of the same configuration as in FIG. 15A are omitted.

[0226] The beam splitter 101N is a semi-cylindrical plate material with a shorter distance between the straight sides A1 and A1' of the beam splitter 101K in FIG. 14(B) and a larger curvature, and is surrounded by a pair of straight sides AN1, AN1' and a pair of curved sides BN1, BN1'. Within the housing 4001, the beam splitter 101N is disposed obliquely with respect to the desk surface. The oblique angle means that one straight side (e.g., AN1) of the beam splitter 101N is disposed near the image display device 1, and the other straight side (e.g., AN1') of the beam splitter 101N is disposed near the retroreflective member 2A. The angle formed by the direction of a line segment connecting both ends of the arc of the curved side surface of the beam splitter 101N corresponds to the Y direction of the desk surface (XY plane). For example, in FIG. 15D, the oblique angle α is approximately 45 degrees (≒45°).

[0227] As with the configuration described above (Figure 3), beam splitter 101N transmits P-polarized light and reflects S-polarized light. For example, it can be formed by depositing an optical thin film on a curved glass or resin substrate. In this case, the angle of incidence of polarized light on beam splitter 101N changes depending on the angle of the curved surface, centered around approximately 45 degrees, and a floating image 3N in space is generated, positioned almost horizontally (on the XY plane).

[0228] The P-polarized image light on optical axis N1 that has been transmitted through beam splitter 101N is converted from P-polarized to S-polarized light by passing through retroreflective member 2A and λ / 4 plate 21A. As a result, the S-polarized image light that has traveled on optical axis N2 after being reflected by retroreflective member 2 is reflected by beam splitter 101N and travels on optical axis N3 in the Z direction.

[0229] When the incident angle of optical axis N2 with respect to the reflective curved surface of beam splitter 101N is approximately 45 degrees as mentioned above, this S-polarized image light travels in the Z direction directly upward (approximately 90 degrees) as shown in the figure, passes through the outside of opening 4002, transparent member 100 and absorptive polarizer 112, and generates and displays a real image, a floating image 3N, at a predetermined position in the Z direction.

[0230] The other image light beams N12 and N13 indicated by dashed arrows, which are emitted in the negative direction in the Y direction, also behave in a similar manner to the aforementioned optical axes N1 and N2, but the reflection of the S-polarized image light corresponding to optical axis N2 on the reflective curved surface of beam splitter 101N has a different angle of incidence depending on the reflection position on the surface of beam splitter 101N.

[0231] 15D(A), the S-polarized reflected image light travels in the Z direction, but the reflection angle of the S-polarized light varies depending on the reflection position on the surface of beam splitter 101N. Since the incident angle of N22, which is on the bottom side of optical axis N2, is smaller than 45 degrees, the light travels to N32, which is tilted in the -Y direction from the Z direction directly above (approximately 90 degrees), and since the incident angle of N23, which is on the top side of optical axis N2, is larger than 45 degrees, the light travels to N33, which is tilted in the +Y direction from the Z direction directly above (approximately 90 degrees), and a real image, floating in space 3N, is generated and displayed at a predetermined position in the Z direction.

[0232] The predetermined position where the floating-in-space image 3N is formed is determined by the optical path length of the optical system including the image display device 1, the beam splitter 101N, and the retroreflective member 2A. The distance between the floating-in-space image 3N and the beam splitter 101N is approximately equal to the distance between the image display device 1 and the beam splitter 101N. Because the beam splitter 101N has the semi-cylindrical shape shown in FIG. 15D(E), the shape of the floating-in-space image is also approximately semi-cylindrical. However, because its curvature is greater than that of the beam splitter 101K shown in FIG. 15A, the floating-in-space image is tilted significantly in the +Y and -Y directions. In other words, the floating-in-space image 3N is more enlarged than the shape of the beam splitter 101N. Therefore, when viewed from the direction N, the user 230N can see the floating-in-space image 3N, which has a convex central portion along the X axis and is enlarged compared to the image displayed on the image display device 1.

[0233] FIG. 15E is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to an eighth embodiment. FIG. 15E shows a configuration in which the beam splitter 101N in the space-floating image display device 400 of the embodiment shown in FIG. 15D is replaced with a beam splitter 101P. FIG. 15E(A) shows a YZ cross-sectional view, FIG. 15E(B) shows an XY top view, and FIG. 15E(C) shows an XZ cross-sectional view. The beam splitter 101P is a conical or lens-shaped plate as shown in FIG. 14(D), with the bottom peripheral portion B3 surrounded by a circle or curve, and the sides slope upward toward the apex of the plate. The beam splitter 101P is positioned at a predetermined angle so that the bottom surface of the beam splitter 101P faces the display panel 11 and the apex of the beam splitter 101P faces the retroreflective member 2A. In this embodiment, differences from the embodiment of FIG. 15D will be described, and repeated description of the same configuration as in FIG. 15D will be omitted.

[0234] The beam splitter 101P is disposed obliquely with respect to the desk surface within the housing 4001. "Oblique" means that one curved side AA of the beam splitter 101P is disposed near the image display device 1, and the other curved side BB opposite the curved side is disposed near the retroreflective member 2A. The angle formed by the direction of the line segment connecting one curved side AA and the other curved side BB of the beam splitter 101P described above corresponds to the Y direction of the desk surface (XY plane), and for example, in FIG. 14, the oblique angle α is about 45 degrees (≒45°).

[0235] As with the previously described configuration (Figure 15D), beam splitter 101P has the property of transmitting P-polarized light and reflecting S-polarized light. For example, it can be formed by depositing an optical thin film on a curved glass or resin substrate. In this case, beam splitter 101P differs from the previously described beam splitter 101N in its cylindrical shape by having a curved surface surrounded by lens-shaped curves. Therefore, S-polarized light reflected by beam splitter 101P is reflected not only in the ±Z directions but also in the ±X directions, generating a spatially floating image 3P positioned approximately on the XY plane.

[0236] The P-polarized image light having optical axis P1 that has been transmitted through beam splitter 101P is converted from P-polarized to S-polarized light by passing through retroreflective member 2A and λ / 4 plate 21A. As a result, the S-polarized image light that has traveled on optical axis P2 after being reflected by retroreflective member 2 is reflected by beam splitter 101P and travels on optical axis P3 in the Z direction.

[0237] When the incident angle of optical axis P2 with respect to the reflective curved surface of beam splitter 101P is approximately 45 degrees as mentioned above, this S-polarized image light travels in the Z direction directly upward (approximately 90 degrees) as shown in the figure, passes through the outside of opening 4002, transparent member 100, and absorptive polarizer 112, and generates and displays a real image, floating in space 3P, at a predetermined position in the Z direction.

[0238] Other image light beams P12 and P13 indicated by dashed arrows, which are emitted in the negative Y direction, behave in the same manner as in Fig. 15D, generating space-floating images PA and PB. Also, image light beams P14 and P15 are reflected in the ±X directions, generating space-floating images PC and PD.

[0239] The predetermined position where the floating-in-space image 3P is formed is determined by the optical distance of the optical path of the optical system including the image display device 1, the beam splitter 101P, and the retroreflective member 2A. The distance between the floating-in-space image 3P and the beam splitter 101P is approximately equal to the distance between the image display device 1 and the beam splitter 101P. Because the beam splitter 101P has a curved surface surrounded by the curves of the lens shape shown in FIG. 14(D), the shape of the floating-in-space image resembles a circle, and because the curvature in the ±X directions is greater than that of the beam splitter 101N shown in FIG. 15D, the floating-in-space image is greatly tilted in the +Y and -Y directions, and the +X and -X directions. In other words, the floating-in-space image 3P is obtained that is greatly enlarged compared to the shape of the beam splitter 101P. Therefore, when viewed from direction P, user 230P can see a floating image 3P that has a convex central portion on the XY plane in the direction of travel of the light that forms the floating image, and is larger than the display image of the image display device 1.

[0240] Fig. 15F is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk according to one embodiment (eighth embodiment). Fig. 15F has the same optical configuration as the embodiment of Fig. 15A in which a beam splitter 101K is arranged inside the space-floating image display device 400, but has the function of correcting image distortion of the floating image generated by the light retroreflected by the retroreflective member through the curved surface of the beam splitter 101K. In this embodiment, differences from the embodiment of Fig. 15A will be explained, and repeated explanations of the same configuration as Fig. 15A will be omitted.

[0241] FIG. 15F(1) shows in more detail the behavior of image light in an optical configuration including the curved beam splitter 101K of FIG. 15A. As shown in the YZ cross-sectional view (A) of FIG. 15F(1), the display device 1 displays P-polarized image light P1-P7 traveling in the -Y direction at equal intervals. When an observer (not shown) views the space-floating image 3K from the front of the device, the S-polarized image light that generates and displays the space-floating image 3K has a wide gap between image light S3 and image light S4 near the central convex portion, as shown in the top view (B) of FIG. 15F(1). As the image approaches both ends (the display device 1 side and the retroreflective member 2A side), the gap narrows, as between image light S1 and image light S2, between image light S6 and image light S7, and so on. In other words, the space-floating image 3K is perceived as having image distortion.

[0242] This phenomenon occurs because beam splitter 101K has a curved surface, and the angle of incidence varies depending on the reflection position of the S-polarized image light on the surface of beam splitter 101K. As a result, although the reflected S-polarized image light travels in the Z direction, depending on the reflection position on the surface of beam splitter 101K, it travels in a direction tilted in the -Y direction or +Y direction from the Z direction directly above (approximately 90 degrees), and a real image floating in space 3K is generated and displayed at a predetermined position in the Z direction.

[0243] If such a floating-in-space image effect is not desired, for example, image light in which image distortion of the floating-in-the-air image has been corrected may be displayed from the display device 1. To correct image distortion of the floating-in-the-air image, the image control unit 1160 in Fig. 10 described above controls image processing of the image signal input from the image signal input unit 1131 and the image signal to be stored in the memory 1109. The image processing is, for example, scaling processing to enlarge, reduce, deform, etc. the image.

[0244] Fig. 15F(2) shows an embodiment for correcting image distortion of a floating-in-the-air image. As shown in the (A) YZ cross-sectional view of Fig. 15F(2), image processing is performed by image control unit 1160 from display device 1, and P-polarized image light that has been corrected so that the closer to the center, the narrower the gap is, like the gap between image light P3' and image light P4', and the closer to both ends (the Z direction side of display device 1 and the -Z direction side of display device 1), the wider the gap is, like the gap between image light P1' and image light P2', or the gap between image light P6' and image light P7', etc., travels in the -Y direction. When an observer (not shown) views the generated and displayed floating image 3K' from the front of the device, as shown in the top view of Figure 15F(2) (B), the distances between the image light S3' and image light S4' near the central convex part, the image light S1' and image light S2' at both ends, and the image light S6' and image light S7' are all equally spaced, and the observer can see the floating image 3K' without image distortion.

[0245] This correction is achieved by correcting the intervals of the image light on the display device 1 side in advance so that even if the angle of incidence of the S-polarized image light varies depending on the reflection position on the curved surface of beam splitter 101K, the image will be equally spaced on space-floating image 3K'. Therefore, depending on the reflection position on the surface of beam splitter 101K, the reflected S-polarized image light will travel in a direction tilted in the -Y direction or +Y direction from the Z direction directly above (approximately 90 degrees), but space-floating image 3K', which is a real image equally spaced at a predetermined position in the Z direction, is generated and displayed, and the observer can view it as space-floating image 3K' without image distortion. This correction is not limited to the embodiment of FIG. 15A, and distortion-free space-floating images can also be generated and displayed for the embodiments of FIGS. 15B to 15E.

[0246] As described above, the space-floating image display device of each embodiment and modification can display a space-floating image with high visibility, suitable for use indoors, for example. Furthermore, the space-floating image display device of this embodiment is configured so that the spatial image displayed is curved, improving the impressive display and operability. More specifically, the beam splitter is configured to have a curved surface, and a curved-shaped space-floating image is displayed. By making the polarization separation member non-planar in this way, it is possible to form a non-planar floating image.

[0247] [Ninth Example] In the space-floating image display device of each embodiment shown in FIGS. 16 to 17D, the image display device 1 is configured to have a curved surface, and is configured to display a curved-surface floating image. Another embodiment (a ninth embodiment) for displaying a curved-surface floating image will be described in detail below with reference to the drawings. In the drawings, identical parts are generally designated by the same reference numerals, and repeated explanations will be omitted. In the drawings, the depiction of each component may not represent its actual position, size, shape, or area, etc., to facilitate understanding of the invention. The display panel 11 is configured to have a curved surface, and is configured to display a curved-surface floating image. By making the polarization separation member non-planar in this way, it is possible to form a non-planar floating image. The display panel 11 may also be called a display unit, liquid crystal display panel, liquid crystal panel, etc.

[0248] FIG. 16 is a perspective view showing an example of the shape of a display panel 11 of a floating-in-the-air image display device suitable for installation on a desk, according to one embodiment (referred to as a ninth embodiment). FIG. 16(A) shows a flat display panel 11, which corresponds to the display panel 11 of the floating-in-the-air image display device shown in FIGS. 11 to 13 and 15A to 15F. In contrast, FIGS. 16(B), 16(C), and 16(D) show examples of curved display panels, where the height of the inner side of the display panel differs from the height of the surrounding edges of the display panel. The liquid crystal display panel 11M of FIG. 16(B) is a semi-cylindrical plate surrounded by a pair of straight sides MA1, MA1′ and a pair of curved sides MB1, MB1′. The liquid crystal display panel 11N of FIG. 16(C) is a semi-cylindrical plate obtained by rotating the liquid crystal display panel 11M of FIG. 16(B) by 90 degrees, and is surrounded by a pair of straight sides NA1, NA1′ and a pair of curved sides NB1, NB1′. The curved edges MB1, MB1', NB1, and NB1' of the liquid crystal display panels 11M and 11N are not limited to portions of a circle or ellipse, but may be curves or polygonal approximation curves with any curvature or bend. The liquid crystal display panel 11P in FIG. 16(D) is surrounded by a pair of straight edges PA1, PA1' and a pair of approximation curves PB1, PB1'. The liquid crystal display panel 11P in FIG. 16(D) is the semicylindrical plate member of the liquid crystal display panel 11M in FIG. 16(B), which is surrounded by the pair of straight edges MA1, MA1' and a pair of curved edges MB1, MB1'. The curved edges MB1, MB1' are configured by polygonal approximation curves PB1 and PB1'. In this embodiment, multiple rectangular display surfaces are arranged in a staircase pattern to form staircase-like approximation curves PB1 and PB1' parallel to the bottom surface of the liquid crystal display panel 11P and corresponding approximation curved surfaces.

[0249] The shapes of the liquid crystal display panels 11M, 11N, and 11P shown in FIGS. 16B, 16C, and 16D are merely examples, and the shapes of the liquid crystal display panels are not limited to these, and may be any non-planar shape.

[0250] FIG. 17A shows a configuration example of a space-floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as the ninth embodiment). FIG. 17A corresponds to the configuration shown in FIG. 2A as a basic configuration. FIG. 17A shows a YZ cross-sectional view of the space-floating image display device 400 shown in FIG. 17A(A) and the image display device 1Q shown in FIG. 17A(B) when viewed from the side. The front of the device here corresponds to the direction in which a user can view the space-floating image 3Q formed by the space-floating image display device 400. The direction Q is the direction in which a user 230Q views the space-floating image 3Q, and corresponds to the negative direction of the Z direction. For explanatory purposes, a coordinate system or direction such as the illustrated (X, Y, Z) may be used. The Z direction is the vertical direction, or up-down direction, the X direction and the Y direction are two orthogonal horizontal directions, the X direction is the depth direction, or front-back direction, and the Y direction is the left-right direction.

[0251] 17A has the same positional relationship of the components (image display device 1Q, beam splitter 101, retroreflective member 2, etc.) as the configuration of FIG. 2A. In order to form the space-floating image 3Q, the components (image display device 1Q, beam splitter 101, retroreflective member 2, etc.) of the space-floating image display device 400 are mutually arranged with a predetermined positional relationship.

[0252] In this embodiment, a housing for mounting and storing the space-floating image display device 400 is omitted. A transparent member 100 such as a glass plate or an absorptive polarizer is provided for the purpose of reducing the influence of external light incident on the space-floating image display device 400 on the retroreflective member 2 and the image display device 1Q. The direction Q is a direction from top to bottom in the Z direction, which is the vertical direction in this example, and is the direction from the viewpoint of the user 230Q to the transparent member 100.

[0253] In this embodiment, image display device 1Q is composed of absorptive polarizer 12Q, liquid crystal display panel 11M, and light source device 13Q. Liquid crystal display panel 11M is a semi-cylindrical plate material as shown in FIG. 16(B) and is surrounded by a pair of straight sides and a pair of curved sides. While liquid crystal display panel 11M is used here as an example, it may be liquid crystal display panel 11N of FIG. 16(C), liquid crystal display panel 11P of FIG. 16(D), or another non-planar liquid crystal panel.

[0254] In the space floating image display device 400, the image display device 1Q is disposed at an angle to the desk surface. "At an angle" means that one straight side (e.g., MA1) of the liquid crystal display panel 11M is disposed far from the retroreflective member 2, and the other straight side (e.g., MA1') of the liquid crystal display panel 11M is disposed near the retroreflective member 2. The angle formed by the direction of the line segment connecting both ends of the arc of the curved side surface of the image display device 1Q corresponds to the Y direction of the desk surface (XY plane), and for example, in Fig. 17A, the angle α, which is the angle of the angle, is about 45 degrees (≒45°).

[0255] The retroreflective member 2 and the λ / 4 plate 21 are arranged in the −Y direction relative to the image display device 1Q. The λ / 4 plate 21 is arranged on the side of the main surface of the retroreflective member 2 where the beam splitter 101 is arranged. In other words, the λ / 4 plate 21 is arranged on the light incident side of the retroreflective member 2. The space-floating image 3Q (shown in a dashed line frame) is arranged between the image display device 1Q and the retroreflective member 2, extending upward in the Z direction from the beam splitter 101 and in the horizontal direction (XY plane). The space-floating image 3Q is an aerial image formed in correspondence with the image display device 1Q. Furthermore, the space-floating image 3Q is an aerial image having a curved surface corresponding to the shape of the image display device 1Q.

[0256] In FIG. 17A, beam splitter 101 has the property of reflecting P-polarized light and transmitting S-polarized light. An example of image light emitted from image display device 1Q in the negative Y direction is shown by a dashed arrow, and will be described using the dashed arrow of optical axis Q1 as a representative example. Image light emitted from curved liquid crystal display panel 11M is light with a predetermined polarization characteristic, for example, P-polarized light (parallel polarization: P stands for parallel). This P-polarized image light is reflected by beam splitter 101 on optical axis Q1 and travels directly on optical axis Q2 corresponding to optical axis Q1 in the negative Y direction toward retroreflective member 2. Beam splitter 101 has the property of reflecting P-polarized light and transmitting S-polarized light (vertical polarization: S stands for Senkrecht).

[0257] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2. The P-polarized image light on optical axis Q2 that is emitted from image display device 1Q and reflected by beam splitter 101 passes through λ / 4 plate 21 twice, once before and once after being reflected by retroreflective member 2, and is thereby converted from P-polarized light to S-polarized light. As a result, the S-polarized image light that returns on optical axis Q2 after being reflected by retroreflective member 2 travels in a direction along optical axis Q3 that is slightly tilted in the Y direction from the Z direction directly above (approximately 90 degrees) as shown in the figure, passes through beam splitter 101 and transparent member 100, and generates and displays a real image, a floating-in-space image 3Q, at a predetermined position in the Z direction. The other image light indicated by the dashed arrows that is emitted in the negative Y direction also behaves in a similar manner to the optical axes Q1 and Q2 described above, but the position and distance from the image light emission curved surface of the image display device 1Q to the beam splitter 101 differ depending on the emission position of the image light.

[0258] Therefore, the S-polarized reflected image light travels in a direction on the optical axis Q3 that is slightly tilted in the Y direction from the Z direction, but as shown in the example of Figure 17A(A), depending on the emission position on the surface of the image display device 1Q, it passes through the beam splitter 101 at different positions, and generates and displays a real image, a floating image 3Q, at a predetermined position in the Z direction.

[0259] The predetermined position where the floating image 3Q is formed is determined according to the optical path length of the optical system including the image display device Q1, the beam splitter 101, and the retroreflection member 2.

[0260] The distance between the floating-in-space image 3Q and the beam splitter 101 (for example, the length from the beam splitter 101 on the optical axis Q3 to the floating-in-space image 3Q) is approximately equal to the distance between the image display device 1Q and the beam splitter 101 (for example, the length from the image display device 1Q on the optical axis Q1 to the beam splitter 101) (indicated by the symbols 〓, 〓*, 〓△ in the figure). Because the liquid crystal display panel 11M has the semi-cylindrical shape described in FIG. 16(B) above, the shape of the floating-in-space image 3Q is also approximately semi-cylindrical. In other words, it has a shape in which the circular curve of the YZ cross section is extended in the X-axis direction. Therefore, when viewed from the direction Q, the user 230Q can see the floating-in-space image 3Q, whose center is raised convexly along the X-axis in the traveling direction of the light that forms the floating-in-the-air image.

[0261] FIG. 17B shows an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as the ninth embodiment). FIG. 17B corresponds to the configuration shown in FIG. 3 as a basic configuration. In FIG. 17B, FIG. 17A(A) shows a YZ cross section of the space-floating image display device when viewed from the side, FIG. 17A(B) shows an XY top view of the device when viewed from the front, and FIG. 17A(C) shows an XZ cross section. The front of the device here is the surface corresponding to the direction in which a user can view the space-floating image 3R formed by the space-floating image display device 400 from the front. The direction R is the direction in which a user 230R views the space-floating image 3R from the front, and corresponds to the negative Z direction.

[0262] The configuration of Fig. 17B is the same as the configuration of Fig. 3 in terms of the positional relationship of the components (image display device 1R, beam splitter 101, retroreflection member 2A, etc.). In order to function as forming the space-floating image 3R, the components of the space-floating image display device 400 (image display device 1R, beam splitter 101, retroreflection member 2A, etc.) are mutually arranged with a predetermined positional relationship. The space-floating image display device 400 is mounted and housed in a housing 4001.

[0263] In this embodiment, a transparent member 100 such as a glass plate and an absorptive polarizing plate 112 are provided for the purpose of reducing the influence of external light incident on the retroreflective member 2A and the image display device 1R through the opening 4002. The direction R is the direction from top to bottom in the Z direction, which is the vertical direction in this example, and is perpendicular to the opening 4002.

[0264] In this embodiment, the image display device 1R is composed of an absorptive polarizer 12R, a liquid crystal display panel 11M, and a light source 13R. The liquid crystal display panel 11M is a semi-cylindrical plate material as shown in Fig. 16(B), and is surrounded by a pair of straight sides and a pair of curved sides.

[0265] Within the housing 4001, the beam splitter 101 is disposed at an angle to the desk surface. "Oblique" means that one straight side of the beam splitter 101 is disposed near the image display device 1R and the other straight side of the beam splitter 101 is disposed near the retroreflective member 2A. The angle formed by the direction of one side of the main surface of the beam splitter 101 corresponds to the Y direction of the desk surface (XY plane), and for example, in FIG. 17B, the angle α, which is the oblique angle, is about 45 degrees (≒45°).

[0266] A retroreflective member 2A and a λ / 4 plate 21A are arranged in the -Y direction across the beam splitter 101 from the image display device 1R. The λ / 4 plate 21A is arranged on the side of the main surface of the retroreflective member 2A where the beam splitter 101 is arranged. In other words, the λ / 4 plate 21A is arranged on the light incident side of the retroreflective member 2A. The space-floating image 3R (shown in a dashed line frame) is located between the housing 106 and the retroreflective member 2A, extending upward from the beam splitter 101 in the Z direction and arranged in the horizontal direction (XY plane). The space-floating image 3R is an aerial image formed corresponding to the liquid crystal display panel 11M. The space-floating image 3R is an aerial image having a curved surface corresponding to the shape of the liquid crystal display panel 11M.

[0267] An opening 1061 is provided on the left surface of the housing 106 in the Y direction and on the right surface of the housing 4001 in the Y direction. The opening 1061 is a portion through which the image light from the image display device 1R passes or is transmitted. A transparent member or the like may be provided in the opening 1061. The image light corresponding to the image displayed on the image display device 1R, more specifically, on the liquid crystal display panel 11M, passes through this opening 1061 and travels toward the beam splitter 101 located in the left direction (negative direction) in the Y direction.

[0268] As with the configuration described above (Figure 3), the beam splitter 101 has the property of transmitting P-polarized light and reflecting S-polarized light. For example, it can be formed by depositing an optical thin film on a glass or resin substrate. In this case, the angle of incidence of the polarized light on the beam splitter 101 is approximately 45 degrees, and a floating image 3R is generated that is positioned almost horizontally (in the XY plane).

[0269] In Figure 17B, an example of image light emitted from image display device 1R in the negative Y direction through opening 1061 is shown by a dashed arrow, and will be described using the dashed arrow of optical axis R1 as a representative example. The image light emitted from liquid crystal display panel 11M is assumed to be light with a predetermined polarization characteristic, for example, P polarization. This P-polarized image light passes through beam splitter 101 on optical axis R1 in the negative Y direction (left) and travels toward retroreflective member 2A on optical axis R2 corresponding to optical axis R1. Beam splitter 101 has the property of passing P-polarized light and reflecting S-polarized light.

[0270] A λ / 4 plate 21A is provided on the light incident surface of the retroreflective member 2A. The P-polarized image light with optical axis R1 that is emitted from the image display device 1R and transmitted through the beam splitter 101 passes through the λ / 4 plate 21A twice, once before and once after being reflected by the retroreflective member 2A, thereby being converted from P-polarized light to S-polarized light. As a result, the S-polarized image light that has traveled on optical axis R2 after being reflected by the retroreflective member 2A is reflected by the beam splitter 101 and travels on optical axis R3 in the Z direction.

[0271] The predetermined position where the space floating image 3R is formed is determined according to the optical distance of the optical path of the optical system including the image display device 1R, the beam splitter 101, and the retroreflection member 2A.

[0272] The distance between the floating image 3R and the beam splitter 101 (for example, the length from the beam splitter 101 on the optical axis R3 to the floating image 3R) is approximately equal to the distance between the image display device 1R and the beam splitter 101 (for example, the length from the image display device 1R on the optical axis R1 to the beam splitter 101) (indicated by the symbol 〓 in the figure). Because the liquid crystal display panel 11M has the semi-cylindrical shape described in FIG. 16(B) above, the shape of the floating image 3R is also approximately semi-cylindrical. In other words, it is a shape in which the circular curve of the YZ cross section is extended in the X-axis direction. Therefore, when viewed from the direction R, the user 230R can see the floating image 3R with a convex central portion along the X-axis in the traveling direction of the light that forms the floating image.

[0273] FIG. 17C is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (ninth embodiment). FIG. 17C shows a configuration in which the image display device 1R in the space-floating image display device 400 of the embodiment of FIG. 17B is replaced with an image display device 1T. FIG. 17C(A) shows a YZ cross-sectional view of the space-floating image display device when viewed from the side, FIG. 17C(B) shows an XY top view when viewed from the front of the device, and FIG. 17C(C) shows an XZ cross-sectional view. The front of the device here corresponds to the direction in which a user can view the space-floating image 3T formed by the space-floating image display device 400 from the front. Direction T is the direction in which a user 230T views the space-floating image 3T from the front, and corresponds to the negative Z direction. In this embodiment, differences from the embodiment of FIG. 17B are explained, and repeated explanations of the same configuration as in FIG. 17B are omitted.

[0274] While the image display device 1R in Fig. 17B uses the semi-cylindrical liquid crystal display panel 11M in Fig. 16(B), the image display device 1T in Fig. 17C uses the liquid crystal display panel 11P shown in Fig. 16(D). The liquid crystal display panel 11P is configured with approximate curves PB1 and PB1' whose curved sides are polygonal, and a plurality of strip-shaped display surfaces are arranged in a stepped pattern to form the stepped approximate curves PB1 and PB1' parallel to the bottom surface of the liquid crystal display panel 11P and the corresponding approximate curved surfaces.

[0275] In Figure 17C(A), an example of image light emitted from image display device 1T in the negative Y direction is shown by a dashed arrow, and will be described using the dashed arrow of optical axis T1 as a representative example. The image light emitted from liquid crystal display panel 11P is assumed to be light with a predetermined polarization characteristic, for example, P polarization. This P-polarized image light passes through beam splitter 101 on optical axis T1 in the negative Y direction (left) and travels toward retroreflective member 2A on optical axis T2 corresponding to optical axis T1. Beam splitter 101 has the property of passing P-polarized light and reflecting S-polarized light.

[0276] The P-polarized image light of optical axis T1 that has passed through beam splitter 101 is converted from P-polarized to S-polarized light by passing through retroreflective member 2A and λ / 4 plate 21A. As a result, the S-polarized image light that has traveled on optical axis T2 after being reflected by retroreflective member 2 is reflected by beam splitter 101 and travels on optical axis T3 in the Z direction. Because the angle of incidence of optical axis T2 with respect to the reflective surface of beam splitter 101 is approximately 45 degrees as described above, this S-polarized image light travels in the Z direction directly upward (approximately 90 degrees) as shown, passes through the outside of opening 4002, transparent member 100, and absorptive polarizing plate 112, and generates and displays space-floating image 3T, which is a real image, at a predetermined position in the Z direction. The S-polarized reflected image light from the other image light indicated by the dashed arrows emitted in the negative Y direction also travels in the Z direction, and a real image, a floating image 3T, is generated and displayed at a predetermined position in the Z direction, as shown in the example of Figure 17C(A).

[0277] A λ / 4 plate 21A is provided on the light incident surface of the retroreflective member 2A. The P-polarized image light with optical axis T1 that is emitted from the image display device 1R and transmitted through the beam splitter 101 passes through the λ / 4 plate 21A twice, once before and once after being reflected by the retroreflective member 2A, and is thereby converted from P-polarized light to S-polarized light. As a result, the S-polarized image light that has traveled on optical axis T2 after being reflected by the retroreflective member 2A is reflected by the beam splitter 101 and travels on optical axis T3 in the Z direction.

[0278] The predetermined position where the floating image 3T is formed is determined by the optical path distance of the optical system including the image display device 1T, the beam splitter 101, and the retroreflective member 2A. The distance between the floating image 3T and the beam splitter 101 (e.g., the length from the beam splitter 101 along the optical axis T3 to the floating image 3T) is approximately equal to the distance between the image display device 1T and the beam splitter 101 (e.g., the length from the image display device 1T along the optical axis R1 to the beam splitter 101) (indicated by the symbol 〓 in the figure). Because the liquid crystal display panel 11P has an approximate shape of a semi-cylinder as shown in Figure 16(D) above, the shape of the floating image 3T also has an approximate shape of a semi-cylinder. In other words, it has a shape obtained by extending the stepped circular curve of the YZ cross section in the -X direction. Therefore, when viewed from direction T, user 230T can visually recognize a floating image 3T with a central portion rising convexly along the X axis in the traveling direction of the light that forms the floating image.

[0279] FIG. 17D is a diagram showing an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (ninth embodiment). FIG. 17D corresponds to the configuration shown in FIG. 4A as a basic configuration. FIG. 17D shows a YZ cross-sectional view of the space-floating image display device 400(A) shown in FIG. 17D(A) and the image display device 1U(B) shown in FIG. 17D(B) when viewed from the side. The front of the device here corresponds to the direction in which the user can view the space-floating image 3U formed by the space-floating image display device 400. The direction U is the direction in which the user 230U views the space-floating image U, and corresponds to the negative direction of the Z direction. For explanatory purposes, a coordinate system or direction such as the illustrated (X, Y, Z) may be used. The Z direction is the vertical direction, or up-down direction, the X direction and the Y direction are two orthogonal horizontal directions, the X direction is the depth direction, or front-back direction, and the Y direction is the left-right direction.

[0280] The configuration of Fig. 17D is similar to the configuration of Fig. 4A in terms of the positional relationship of the components (image display device 1U, beam splitter 101, retroreflective member 5, etc.). In order to form the space-floating image 3U, the components of the space-floating image display device 400 (image display device 1U, beam splitter 101, retroreflective member 5, etc.) are mutually arranged with a predetermined positional relationship.

[0281] In this embodiment, a housing for mounting and storing the space-floating image display device 400 is omitted. A transparent member 100 such as a glass plate or an absorptive polarizer is provided for the purpose of reducing the influence of external light incident on the space-floating image display device 400 on the retroreflective member 5 and the image display device 1U. The direction U is the direction from top to bottom in the Z direction, which is the vertical direction in this example, and is the direction from the viewpoint of the user U toward the transparent member 100.

[0282] In this embodiment, the image display device 1U is composed of an absorptive polarizer 12U, a liquid crystal display panel 11M, and a light source device 13U. The liquid crystal display panel 11M is a semi-cylindrical plate material as shown in FIG. 16(B), and is surrounded by a pair of straight sides and a pair of curved sides. While the liquid crystal display panel is shown as the liquid crystal display panel 11M here as an example, it may be the liquid crystal display panel 11N shown in FIG. 16(C), the liquid crystal display panel 11P shown in FIG. 16(D), or another liquid crystal panel with a non-planar shape.

[0283] In the space floating image display device 400, the image display device 1U is disposed at an angle to the desk surface. "At an angle" means that one straight side (e.g., MA1) of the liquid crystal display panel 11M is disposed far from the retroreflective member 5, and the other straight side (e.g., MA1') of the liquid crystal display panel 11M is disposed near the retroreflective member 5. The angle formed by the direction of the line segment connecting both ends of the arc of the curved side surface of the image display device 1U corresponds to the Y direction of the desk surface (XY plane), and for example, in Fig. 17D, the angle α, which is the angle of the angle, is about 45 degrees (≒45°).

[0284] A main optical axis 9020U representing the light beam emitted from the display device 1U travels toward the retroreflector 5 and is incident on the retroreflector 5 at the incident angle α. The retroreflector 5 is an optical member having the optical property of retroreflecting light rays in at least some directions. The retroreflector 5 retroreflects the main optical axis 9020U in the X and Y directions while traveling in the Z direction. As a result, the reflected light ray 9021U travels along an optical path mirror-symmetrical with respect to the main optical axis 9020U, traveling away from the retroreflector 5, passing through the transparent member 100, and forming a space-floating image 3U as a real image on the imaging plane.

[0285] Other image light beams indicated by dashed arrows that are emitted diagonally upward in the Y direction also behave in a similar manner to the aforementioned main optical axis 9020U, but the position and distance from the image light emission curved surface of the image display device 1U to the retroreflector 5 differ depending on the emission position of the image light.

[0286] Therefore, as shown in the example of Figure 17D(A), depending on the emission position on the surface of the image display device 1U, the light travels in a direction of an optical axis that is mirror-symmetrical with respect to the retroreflector 5 at different positions and is slightly tilted in the -Y direction from the Z direction, and a real image, a floating image 3U, is generated and displayed at a predetermined position in the Z direction.

[0287] The predetermined position where the space floating image 3U is formed is determined according to the optical path of the optical system including the image display device 1U and the retroreflective member 5.

[0288] The distance between the floating image 3U and the retroreflective member 5 (for example, the length from the retroreflective member 5 of the optical axis 9021U to the floating image 3U) is approximately equal to the distance between the image display device 1U and the retroreflective member 5 (for example, the length from the image display device 1U of the optical axis 9020U to the retroreflective member 5) (indicated by the symbols 〓, 〓*, and 〓△ in the figure). Because the liquid crystal display panel 11M has the semi-cylindrical shape described in Figure 16(B) above, the floating image 3U also has an approximately semi-cylindrical shape. In other words, it has a shape in which the circular curve of the YZ cross section is extended in the X-axis direction. Therefore, when viewed from the direction U, the user 230U can see the floating image 3U, whose center is convex along the X-axis in the traveling direction of the light that forms the floating image.

[0289] [Tenth Example] The space floating image display device of each example shown in Figures 18A to 18B has a display unit configured to have a curved surface, and is configured to display a curved space floating image. Hereinafter, with reference to the drawings, an embodiment of the present disclosure will be described in detail for another example (Example 10) that displays a curved space floating image. In the drawings, the same parts are generally given the same reference numerals, and repeated explanations will be omitted. In the drawings, the depiction of each component may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention.

[0290] FIG. 18A shows an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (referred to as the tenth embodiment). FIG. 18A corresponds to the basic configuration shown in FIG. 4A. FIG. 18A shows a configuration in which image display device 1U in space-floating image display device 400 of the embodiment of FIG. 17D is replaced with image display device 1V. FIG. 18A shows a YZ cross-sectional view of the space-floating image display device as viewed from the side. The front of the device here corresponds to the side from which a user can view space-floating image 3V formed by space-floating image display device 400. Direction V is the direction from which user 230V views space-floating image V, and corresponds to the negative side of the Z direction. In this embodiment, differences from the embodiment of FIG. 17D will be explained, and repeated explanations of the same configuration as in FIG. 17D will be omitted.

[0291] While the image display device IU of FIG. 17D uses the liquid crystal display panel 11M of FIG. 16(B), the image display device 1V of FIG. 18A uses a mask 800 having a curved surface as shown in FIG. 18B.

[0292] FIG. 18B shows a configuration example of an image display device 1V using a mask 800. The image display device 1V is composed of an absorptive polarizer 12V, a mask 800, and a light source device 13V, where the light source device 13V is a light source that emits visible light. FIG. 18B(A) shows a front view of the mask 800, and FIG. 18B(B) shows a cross-sectional view of the image display device 1V. The mask 800 is disposed on the light output surface of the light source device 13V and blocks a portion of the light output from the light source device 13V, thereby displaying a still image. Referring to FIG. 10, the liquid crystal display panel 11 is replaced with the mask 800, and a still image is displayed using a mask that blocks a portion of the light output from the light source device 13V, without using a display panel.

[0293] The exit surface of the mask 800 is not flat but curved, similar to the liquid crystal display panels 11M or 11N of Figure 16(B) or Figure 16(C), and the height of the inside of the mask 800 is different from the peripheral edges of the mask 800.

[0294] The mask 800 is composed of non-light-transmitting areas 801 and 802 (black areas) and light-transmitting area 803 (white area), and in this example, the letter "A" is formed as the non-light-transmitting area 802 in the light-transmitting area 803.

[0295] The mask 800 can be realized, for example, by using a glass substrate or a transparent plastic substrate in the light-transmitting region 803, and providing a coating that absorbs / reflects visible light in the non-light-transmitting regions 801 and 802, printing light-absorbing ink, or adhering a thin plate that does not transmit light, such as metal, to the surface of the substrate.

[0296] The light source device 13V may be any light source device that emits visible light, and may be a lamp, a single-color LED, a multi-color LED, or the like.

[0297] A main optical axis 9020V representing a light beam emitted from the image display device 1V in FIG. 18A travels toward the retroreflector 5 and is incident on the retroreflector 5 at the incident angle α. The retroreflector 5 is an optical element having the optical property of retroreflecting light rays in at least some directions. The retroreflector 5 retroreflects the main optical axis 9020V in the X and Y directions while traveling in the Z direction. As a result, the reflected light ray 9021V travels along an optical path mirror-symmetrical with respect to the main optical axis 9020V, traveling away from the retroreflector 5, passing through the transparent member 100, and forming a space-floating image 3V as a real image on the imaging plane.

[0298] Other image light beams indicated by dashed arrows that are emitted diagonally upward in the Y direction also behave in a similar manner to the aforementioned main optical axis 9020V, but the position and distance from the image light emission curved surface of the image display device 1V to the retroreflector 5 differ depending on the emission position of the image light.

[0299] Therefore, as shown in the example in Figure 18A, depending on the emission position on the surface of the image display device 1V, the light travels in a direction of an optical axis that is mirror-symmetrical with respect to the retroreflector 5 at different positions and is slightly tilted in the -Y direction from the Z direction, and a real image, a floating image 3V in space, is generated and displayed at a predetermined position in the Z direction.

[0300] The predetermined position where the space floating image 3V is formed is determined according to the optical path of the optical system including the image display device 1V and the retroreflective member 5.

[0301] The distance between the space-floating image 3V and the retroreflective member 5 (for example, the length from the retroreflective member 5 of the optical axis 9021V to the space-floating image 3V) is approximately equal to the distance between the image display device 1V and the retroreflective member 5 (for example, the length from the image display device 1V of the optical axis 9020V to the retroreflective member 5) (indicated by the symbols 〓, 〓*, 〓△ in the figure). Since the mask 800 has a semi-cylindrical shape like the liquid crystal display panel 11M or 11N shown in Figure 16(B) or (C) above, the shape of the space-floating image 3V is also approximately semi-cylindrical. In other words, it has a shape obtained by extending the circular curve of the YZ cross section in the X-axis direction. Therefore, when viewed from direction V, user 230V can see a floating image with a convex center along the X-axis in the direction of travel of the light forming the floating image. In other words, in the case of mask 800 in FIG. 18B(A), a floating image 3V of the letter "A" with a convex center along the X-axis can be seen. If a multicolor LED is used for light source device 13V, the display color of floating image 3V can be changed, making it possible to change the display color when floating image 3V is touched. This embodiment is suitable for generating floating images of buttons with text, etc., with a simple configuration.

[0302] [Eleventh Example] The space-floating image display device of each embodiment shown in Figures 19A and 19B has a display unit configured to have a curved surface, and is configured to display a curved-surface-shaped space-floating image. Regarding another embodiment (Example 11) that displays a curved-surface-shaped space-floating image, the embodiment of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical parts are generally designated by the same reference numerals, and repeated explanations will be omitted. In the drawings, the depiction of each component may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention.

[0303] Fig. 19A shows an example of the configuration of a space-floating image display device suitable for installation on a desk, according to one embodiment (hereinafter referred to as an eleventh embodiment). Fig. 19A corresponds to the configuration shown in Fig. 3 as a basic configuration. Fig. 19A is an embodiment in which the mid-air operation detection sensor 1351 and the imaging unit 510 provided in the space-floating image display device 400 of Fig. 10 are added to or replaced with a capacitance touch sensor 700, which is another example of a method for detecting mid-air operations such as touching the space-floating image 3R with a fingertip.

[0304] 19A(A) shows a YZ cross-sectional view of the space floating image display device when viewed from the side, and FIG. 19A(B) shows a perspective view of the XY plane of the capacitance touch sensor. In this embodiment, differences from the embodiment in FIG. 17B are explained, and repeated explanations of the same configuration as in FIG. 17B are omitted.

[0305] The capacitive touch sensor 700 calculates touch coordinates by utilizing the principle that capacitance increases when a finger approaches a sensor electrode. The capacitive touch sensor 700 is a transparent sheet touch sensor in which transparent sensor electrodes 701-707 made of transparent conductive polymer are arranged over the entire surface of a glass substrate. The sensor electrodes 701-707 detect the capacitance at their respective positions.

[0306] 19A(B), the sensor electrodes 701 to 707 are only representatively provided in one row in the Y direction. In this configuration, the sensor electrodes 701 to 707 are transparent electrodes, so that the image light traveling from the inside of the space-floating image display device 400 to the outside through the opening 4002, passing through the transparent member 100 and the absorptive polarizer 112 and proceeding in the Z direction also passes through the capacitive touch sensor 700, and can generate and display the space-floating image 3R, which is a real image.

[0307] Fig. 19B is a block diagram showing an example of the internal configuration of a space floating image display device. In this embodiment, differences from the embodiment in Fig. 10 will be described, and repeated explanations of the same configuration as in Fig. 10 will be omitted. Fig. 19B adds a touch sensor 700 to Fig. 10. The coordinates of the XY plane of the finger of the user 230R and the height direction (Z direction) described below can be calculated from the sensor signals detected by the sensor electrodes 701 to 707 of the touch sensor 700 by the mid-air operation detection unit 1350.

[0308] When user 230R touches and operates a curved-surface floating-in-space image object 3R, it is necessary to calculate whether or not the user's finger has made contact with the curved-surface floating-in-space image 3R object and the position (contact position) where user 230R's finger has made contact with the object. For a planar floating-in-space image, the height in the Z direction is uniform, so the capacitive touch sensor 700 only needs to detect the contact position on the XY plane. By setting a certain capacitance threshold, the capacitive touch sensor 700 sequentially senses each of the sensor electrodes 701-707 on the XY plane and detects the finger's touch position from the sensor electrode 701-707 where the capacitance value exceeds the threshold, as has been conventionally used as a non-contact sensor. However, because a curved floating-in-space image object like the floating-in-space image 3R has height differences in the Z direction, determining whether or not user 230R's finger has made contact with the object in the floating-in-space image 3R requires detecting the height differences in the Z direction along the curved shape of the floating-in-space image 3R.

[0309] In the example of FIGS. 19A(A) and (B), the presence or absence of contact with an object is determined by focusing on the difference in capacitance C1 to C7 between the finger and the sensor electrodes 701 to 707 that occurs due to the difference in height along the curved shape of the floating image 3R, i.e., the difference in distance.

[0310] 19A(A) and (B), it is assumed that the user 230R touches the floating-in-the-air image touch point 710 and the floating-in-the-air image touch point 720 of the curved floating-in-the-air image 3R with his / her finger. The capacitance between the finger 710A and the corresponding sensor electrode 702 of the capacitive touch sensor 700 at the floating-in-the-air image touch point 710 is C2, and the capacitance between the finger 720A and the corresponding sensor electrode 704 of the capacitive touch sensor 700 at the floating-in-the-air image touch point 720 is C4. In this case, the distance between the finger 710A and the sensor electrode 702 of the capacitive touch sensor 700 at the floating-in-the-air image touch point 710 is shorter than the distance between the finger 720A and the sensor electrode 704 of the capacitive touch sensor 700 at the floating-in-the-air image touch point 720. Therefore, the capacitance C2 of the floating-in-the-air image touch point 710 is larger than the capacitance C4 of the floating-in-the-air image touch point 720, and the difference in the height direction, that is, the Z direction, can be distinguished.

[0311] The curved shape of the space-floating image 3R and the height from the surface of the capacitive touch sensor 700 are determined by the relative positioning of the curved shape of the liquid crystal display panel 11M and the beam splitter 101, in other words, the distance between the curved shape of the liquid crystal display panel 11M and the beam splitter 101. The curved shape of the space-floating image 3R and the height from the surface of the capacitive touch sensor 700 are determined at the design stage, and from this height information, the capacitances C1 to C7 between a finger positioned on the curved surface of the space-floating image 3R and the sensor electrodes 701 to 707 can also be calculated in advance. Therefore, by setting the detection threshold of the capacitive touch sensor 700 using the values of the capacitances C1 to C7 calculated in advance, it is possible to determine whether a finger has come into contact with the curved surface of the space-floating image 3R.

[0312] The detection threshold of the capacitance sensor 700 is set to a different value depending on the distance between the floating-in-the-air image 3R and the capacitance touch sensor 700. In other words, the detection threshold of the capacitance sensor 700 varies depending on the non-planar shape of the floating-in-the-air image 3R.

[0313] Furthermore, for example, the heights from the surface of the capacitance touch sensor 700 to the floating-in-the-air image 3R of the floating-in-the-air image touch point 710 and the floating-in-the-air image touch point 730 are approximately the same, and therefore the corresponding capacitances C2 and C6 are also approximately the same, but the corresponding sensor electrodes are different, sensor electrodes 702 and 706. Therefore, by combining the sequential sensing of the sensor electrodes 701 to 707 on the XY plane of the conventionally used capacitance touch sensor 700 with setting a detection threshold according to the non-planar shape of the floating-in-the-air image 3R, it is possible to distinguish between the floating-in-the-air image touch point 710 and the floating-in-the-air image touch point 730.

[0314] This makes it possible to detect mid-air operations such as touching the non-planar floating image 3R with a fingertip, improving operability. Furthermore, the capacitance sensor 700 may be combined with mid-air operation detection by the mid-air operation detection sensor 1351 or the imaging unit 510, enabling more accurate detection.

[0315] In the above-described embodiment, the configuration of the V-type space-floating image display device is such that the image display device 1 and the retroreflective member 2 are arranged to resemble the letter V when viewed from the side. Also, the configuration of the Z-type space-floating image display device is such that the image display device 1 and the retroreflective member 2 are arranged face to face, and the beam splitter 101 is arranged between the image display device 1 and the retroreflective member 2 at a predetermined angle (for example, an angle of 45 degrees or the like relative to the image display device 1 or the retroreflective member 2), and this arrangement is such that it resembles the letter Z when viewed from the side.

[0316] This has the effect of improving the visibility and operability of the floating image for users. When the generated floating image is used as a non-contact user interface, it has the effect of preventing or reducing operational errors and input errors, and is more impressive to users.

[0317] The technology in this embodiment displays high-resolution, high-brightness floating images in a floating state, making it possible to use these floating images as a contactless user interface, allowing users to operate them without worrying about contact infection. This contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs), "Good health and well-being for all."

[0318] 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 retroreflective material, 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 "9th Sustainable Development Goal (SDGs) - Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation" advocated by the United Nations.

[0319] Furthermore, the technology according to the embodiment enables the formation of floating images using highly directional (linear) video light. The technology according to the present embodiment makes it possible to provide a non-contact user interface with low risk of people other than the user viewing the floating images, even when displaying images that require high security, such as those on kiosk terminals, or highly confidential images that should be kept secret from people directly facing the user, by displaying highly directional video light. By providing the above-described technology, the present invention contributes to "Sustainable Cities and Communities," one of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Explanation of symbols]

[0320] 1, 1Q, 1R, 1T, 1U, 1V: Video display device, 2, 2A, 2B, 5: Retroreflective material, retroreflective plate 3,3A,3B,3C,3D,3E,3F,3J,3K,3Q,3R,3T,3U,3V: Space floating image, 11, 11M, 11N, 11P, 11U: liquid crystal display panel, 12, 12Q, 12R, 12U, 12V, 112: Absorption polarizer, 13,13Q,13V: Light source device, 21,21A,21B: λ / 4 plate, 203: Light guide, 100, 100A, 100B, 100C: transparent material, 101, 101A, 101B, 101C, 101D, 101E, 101F, 101J, 101G, 101K, 101L, 101M, 101N, 101P: beam splitter (polarized light separating member), 1010: Beam splitter angle adjustment unit, 106: Housing of image display unit, 300: image display device unit, 400: space floating image display device, 1061: opening, 4001: Housing, 4002: Opening, 230A,230B,230C,230D,230E,230F,230J,230K,230M,230L,230N,230P,230Q,230R,230T,230U,230V:User, 310: piston mechanism, 310A, 310B, 310C: pistons, 330, 331, 332, 333: hinge mechanisms, 500: control unit, etc., 510: imaging unit, 600: unwanted light, 1110: control unit, 1160: video control unit, 1350: mid-air operation detection unit, 1351: mid-air operation detection sensor, 700: capacitance touch sensor, 701 to 707: sensor electrodes, 710A, 720A, 730A: fingers, 800: mask

Claims

1. A floating-in-the-air image display device, At least a display unit that displays an image; an optical system that retroreflects image light emitted from the display unit, The reflected light retroreflected by the optical system forms a floating image, The display unit is made non-planar, thereby forming the floating image in a non-planar shape. A floating video display device.

2. 2. The floating-in-the-air image display device according to claim 1, The non-planar shape is a curved shape. A floating video display device.

3. 2. The floating-in-the-air image display device according to claim 1, The non-planar shape is a semi-cylindrical shape and is surrounded by a pair of straight sides and a pair of curved sides. A floating video display device.

4. 2. The floating-in-the-air image display device according to claim 1, the non-planar shape is stepped; A floating video display device.

5. 2. The floating-in-the-air image display device according to claim 1, a polarization separation member that transmits or reflects a part of the image light emitted from the display unit, the polarization separating member is disposed at a predetermined angle with respect to the display unit, The reflected light from the polarization separating element is incident on the optical system, and the reflected light retroreflected by the optical system passes through the polarization separating element to form a floating image. A floating video display device.

6. 2. The floating-in-the-air image display device according to claim 1, a polarization separation member that transmits or reflects a part of the image light emitted from the display unit, the polarization separating member is disposed between the display unit and the optical system at a predetermined angle with respect to the display unit and the optical system; The image light from the display unit passes through the polarization separation member and enters the optical system, and the reflected light retroreflected by the optical system is reflected by the polarization separation member to form a floating image. A floating video display device.

7. 2. The floating-in-the-air image display device according to claim 1, The image light emitted from the display unit is retroreflected and transmitted through the optical system to form a floating image. A floating video display device.

8. 2. The floating-in-the-air image display device according to claim 1, In the traveling direction of light forming the floating-in-the-air image, a central portion of the floating-in-the-air image is higher than a vicinity of the display unit of the floating-in-the-air image and a vicinity of the optical system of the floating-in-the-air image. A floating video display device.

9. 2. The floating-in-the-air image display device according to claim 1, the display unit is a liquid crystal display panel or an organic EL panel; A floating video display device.

10. 2. The floating-in-the-air image display device according to claim 1, The display unit is a light source that emits visible light, such as a lamp, a single-color LED, or a multi-color LED. A floating video display device.

11. 2. The floating-in-the-air image display device according to claim 1, a mask for blocking part of the emitted light is disposed on the emission surface of the display unit; A floating video display device.

12. 2. The floating-in-the-air image display device according to claim 1, an aerial operation detection sensor is disposed to detect a touch on the floating-in-the-air image; A floating video display device.

13. 13. The airborne image display device according to claim 12, the mid-air operation detection sensor detects a touch on a non-planar surface of the floating-in-the-air image; A floating video display device.

14. 13. The airborne image display device according to claim 12, the aerial operation detection sensor is a capacitance sensor that includes a plurality of sensor electrodes for detecting capacitance and detects the position of the touch from the sensor electrode at a point where the capacitance exceeds a detection threshold; the detection threshold varies depending on the non-planar shape of the floating-in-the-air image; A floating video display device.

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