Floating-in-the-air image display

Abstract

To provide a more suitable air floating video display device. The present invention contributes to "health and well-being for all three people", "9 Build a foundation for industry and technical innovation", and "11 Keep living", which are sustainable development goals (SDGs).SOLUTION: The floating-in-the-air image display device includes a display device that displays an image, a retroreflector that reflects image light from the display device and displays a floating-in-the-air image in the air by the reflected light, and a circuit unit on which a substrate is mounted. The circuit unit does not overlap with the retroreflective plate and the display device, the retroreflective plate is disposed on a side of the floating image with respect to the circuit unit, and the display device is disposed on a side opposite to the floating image with respect to the circuit unit.SELECTED DRAWING: Figure 22

Description

[Technical Field]

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

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

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

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

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

[0006] In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above problems, but one example is a floating image display device including a display device that displays an image, a retroreflector that reflects image light from the display device and displays a floating image in the air using the reflected light, and a circuit unit on which a substrate is mounted, wherein the circuit unit does not overlap the retroreflector and the display device, the retroreflector is disposed on the floating image side of the circuit unit, and the display device is disposed on the opposite side of the circuit unit from the floating image. [Effects of the Invention]

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

[0008] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image display device according to an embodiment of the present invention; [Figure 2A] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a floating-in-the-air image display device according to an embodiment of the present invention; [Figure 2B] 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 2C] 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 2D] 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 2E] 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 2F] FIG. 1 is a side view showing a corner reflector that constitutes a retroreflector that constitutes a floating-in-the-air image display device according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention. [Figure 4A] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4B] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 4C] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 5] 1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 6]1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 7] 1 is a cross-sectional view showing an example of a specific configuration of a light source device according to an embodiment of the present invention. [Figure 8] 1 is a layout diagram showing a main part of a space floating image display device according to an embodiment of the present invention; [Figure 9] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a configuration of a display device according to an embodiment of the present invention. [Figure 11] 1 is an explanatory diagram for explaining the light source diffusion characteristics of an image display device according to an embodiment of the present invention. [Figure 12] 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device according to an embodiment of the present invention; [Figure 13A] 1 is a diagram showing an example of 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 13B] 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 14A] 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 14B] 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 15] 1 is an enlarged view illustrating a configuration of a main part of a floating image display device according to an embodiment of the present invention; [Figure 16] 1 is an enlarged view illustrating a configuration of a main part of a floating image display device according to an embodiment of the present invention; [Figure 17] 1 is a diagram showing an example of a configuration of an image light control sheet according to an embodiment of the present invention. [Figure 18] 1 is an enlarged view illustrating a main part configuration of a space floating image display device according to an embodiment of the present invention; [Figure 19]FIG. 10 is a diagram showing an example of various setting values ​​in the space floating image display device according to one embodiment of the present invention. [Figure 20] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 21] FIG. 21 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 20. [Figure 22] FIG. 21 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 20. [Figure 23] FIG. 21 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 20. [Figure 24] FIG. 21 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 20. [Figure 25] FIG. 21 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 20. [Figure 26] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 27] FIG. 27 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 26. [Figure 28] 1 is a diagram showing an example of the configuration of a space floating image display device according to an embodiment of the present invention; [Figure 29] FIG. 29 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 28. [Figure 30] FIG. 29 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 28. [Figure 31] FIG. 29 is a diagram showing an example of the inside of the space floating image display device shown in FIG. 28. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

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

[0013] <Example of how to use the space floating image display device> FIG. 1 is a diagram showing an example of a usage form of a space-floating image display device according to an embodiment of the present invention, and is a diagram showing the overall configuration of the space-floating image display device according to this embodiment. The specific configuration of the space-floating image display device will be described in detail using FIG. 2 and other figures. Light with a narrow-angle directional characteristic and specific polarization is emitted from image display device 1 as an image light beam, reflected by the optical system within the space-floating image display device, and then incident on retroreflector 2. It is then retroreflected and transmitted through transparent member 100 (glass, etc.), forming a real aerial image (space-floating image 3) on the outside of the glass surface. In the following embodiments, the retroreflector 2 (retroreflector) is used as an example of a retroreflector. However, the retroreflector 2 of the present invention is not limited to a planar plate, and is used as an example of a concept including a sheet-like retroreflector attached to a planar or non-planar member, or an entire assembly in which a sheet-like retroreflector is attached to a planar or non-planar member. Furthermore, since the light rays reflected by the retroreflector 2 have the optical property of forming an image, the retroreflector 2 may also be expressed as an imaging optical member or an imaging optical plate.

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

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

[0016] <Configuration example of optical system for space floating image display device> An example of the configuration of an optical system of a space floating image display device will be described with reference to Fig. 2A. The optical system of Fig. 2A is an optical system that uses a retroreflector 5. Hereinafter, the example of the configuration of the optical system will be described in more detail with reference to Figs. 2A to 2F.

[0017] 2A is a diagram showing an example of the main components and retroreflection components of a space floating image display device according to one embodiment of the present invention. A display device 1 that emits image light is provided obliquely on a transparent member 100 such as glass. The display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light.

[0018] A chief ray 9020 representing the light beam emitted from the display device 1 travels toward the retroreflector 5 and is incident on the retroreflector 5 at an incident angle α. The incident angle α may be, for example, 45°. However, the incident angle α is not limited to 45°, and may also be, for example, 45°±15°.

[0019] 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.

[0020] 2B, 2C, 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.

[0021] The light beam that forms the floating image 3 is a collection of light rays that converge from the retroreflector 5 to the optical image of the floating image 3, and these light rays continue to travel in a straight line even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is an image with high directionality, unlike a diffuse image formed on a screen by a general projector or the like. Therefore, in the configuration of Figure 2, when a user views the floating image 3 from the direction of arrow A, the floating image 3 is perceived as a bright image. However, when another person views the floating image 3 from the direction of arrow B, the floating image 3 cannot be perceived as an image at all. This characteristic is suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0022] An example of the configuration of the retroreflector 5 will be described using Figures 2B and 2C. The retroreflector 5 has a configuration in which multiple corner reflectors 9040 are arranged in an array on the surface of a transparent member. This may also be called a corner reflector array or a polyhedral reflector array. The specific configuration of the corner reflector 9040 will be described in detail using Figures 2D, 2E, and 2F. 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.

[0023] 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.

[0024] 2D, 2E, and 2F, the configuration and effects of the corner reflector 9040 that constitutes the retroreflector 5 will be described. The corner reflector 9040 is a rectangular parallelepiped with only two specific faces being mirror surfaces 9041 and 9042, and the other four faces being made of transparent materials. The retroreflector 5 has a configuration in which these corner reflectors 9040 are arrayed so that corresponding mirror surfaces face in the same direction.

[0025] 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).

[0026] 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.

[0027] 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.

[0028] In the optical system of Fig. 2A, the retroreflector 5 has retroreflection properties in two axes and specular reflection in the other axis. 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.

[0029] 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.

[0030] 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.

[0031] The resolution of the space-floating image formed by the light beams from the display device 1 depends not only on the resolution of the liquid crystal display panel 11 but also on the diameter D and pitch P (not shown) of the retroreflective portion of the retroreflector 5 shown in Figures 2B and 2C. For example, when using a 7-inch WUXGA (1920 x 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective portion is 240 μm and the pitch P is 300 μm, one pixel of the space-floating image will be equivalent to 300 μm. As a result, the effective resolution of the space-floating image will be reduced to about one-third.

[0032] Therefore, in order to make the resolution of the spatial floating image equivalent to that of the display device 1, it is desirable to make the diameter D and pitch P of the retroreflective portion close to one pixel of the liquid crystal display panel. On the other hand, to suppress the occurrence of moire caused by the retroreflective plate and the pixels of the liquid crystal display panel, it is advisable to design the pitch ratio of each to be a different integer multiple of one pixel. Also, it is advisable to arrange the shape so that none of the sides of the retroreflective portion overlaps with any of the sides of one pixel of the liquid crystal display panel.

[0033] The shape of the retroreflector (imaging optical plate) according to this embodiment is not limited to the above example. It may have various shapes that achieve retroreflection. Specifically, it may be a variety of cubic corner bodies, a corner reflector array, a slit mirror array, a dihedral corner reflector array, a polyhedral reflector array, or a shape in which a combination of these reflective surfaces is periodically arranged. Alternatively, a capsule lens-type retroreflector element with periodically arranged glass beads may be provided on the surface of the retroreflector according to this embodiment. The detailed configuration of these retroreflectors can be achieved using existing technology, so a detailed description will be omitted. Specifically, the technology disclosed in JP 2017-33005 A, JP 2019-133110 A, JP 2017-67933 A, WO 2009 / 131128 A, etc. may be used.

[0034] 2A, the image light emitted from the display device 1 may be in either polarization state, either S-polarized or P-polarized.

[0035] As described above, the optical system of FIG. 2A can form a more suitable floating image in space.

[0036] According to the optical system of FIG. 2A described above, it is possible to provide a brighter, higher quality floating image in space.

[0037] <<Block diagram of the internal configuration of the space floating image display device>> Next, a description will be given of a block diagram of the internal configuration of the space-floating image display device 1000. Fig. 3 is a block diagram showing an example of the internal configuration of the space-floating image display device 1000.

[0038] The space-floating image display device 1000 includes a retroreflection unit 1101, an image display unit 1102, a light guide 1104, a light source 1105, a power supply 1106, an external power supply input interface 1111, an operation input unit 1107, a nonvolatile memory 1108, a memory 1109, a control unit 1110, a video signal input unit 1131, an audio signal input unit 1133, a communication unit 1132, an aerial operation detection sensor 1351, an aerial operation detection unit 1350, an audio output unit 1140, a microphone 1139, an image control unit 1160, a storage unit 1170, an imaging unit 1180, etc. In addition, the space-floating image display device 1000 may also include a removable media interface 1134, an attitude sensor 1113, a transmissive self-luminous image display device 1650, a second display device 1680, or a secondary battery 1112.

[0039] Each component of the space floating image display device 1000 is disposed in a housing 1190. The imaging unit 1180 and the mid-air operation detection sensor 1351 shown in FIG.

[0040] The retroreflector 1101 in Fig. 3 corresponds to the retroreflector 5 in Fig. 2A. The retroreflector 1101 retroreflects light modulated by the image display unit 1102. Of the light reflected from the retroreflector 1101, the light output to the outside of the space-floating image display device 1000 forms the space-floating image 3. When the optical system in Fig. 2A is applied, the retroreflector 1101 corresponds to the retroreflector 5 in Fig. 2A.

[0041] The image display unit 1102 in Fig. 3 corresponds to the liquid crystal display panel 11 in Fig. 2A. The light source 1105 in Fig. 3 corresponds to the light source device 13 in Fig. 2A. The image display unit 1102, the light guide 1104, and the light source 1105 in Fig. 3 correspond to the display device 1 in Fig. 2A.

[0042] The video display unit 1102 is a display unit that generates a video by modulating transmitted light based on a video signal input under the control of a video control unit 1160 (described later). The video display unit 1102 (the above-described liquid crystal display panel 11) may be, for example, a transmissive liquid crystal panel, but is not limited to this. Alternatively, the video display unit 1102 may be, for example, a reflective liquid crystal panel that modulates reflected light, a DMD (Digital Micromirror Device: registered trademark) panel, or the like.

[0043] The light source 1105 generates light for the image display unit 1102 and is a solid-state light source such as an LED (Light Emitting Diode) or a laser light source. The power source 1106 converts AC current input from the outside via the external power input interface 1111 into DC current and supplies power to the light source 1105. The power source 1106 also supplies the necessary DC current to each unit within the space-floating image display device 1000. The secondary battery 1112 stores the power supplied from the power source 1106. The secondary battery 1112 also supplies power to the light source 1105 and other components that require power via the external power input interface 1111 when power is not supplied from the outside. In other words, when the space-floating image display device 1000 is equipped with the secondary battery 1112, the user can use the space-floating image display device 1000 even when power is not supplied from the outside.

[0044] The light guide 1104 guides light generated by the light source 1105 and irradiates it onto the video display unit 1102. The combination of the light guide 1104 and the light source 1105 can also be called a backlight for the video display unit 1102. The light guide 1104 may be configured mainly using glass. The light guide 1104 may be configured mainly using plastic. The light guide 1104 may be configured using a mirror. Various methods are possible for combining the light guide 1104 and the light source 1105. Specific configuration examples of the combination of the light guide 1104 and the light source 1105 will be described in detail later.

[0045] The aerial operation detection sensor 1351 is a sensor that detects an operation of the floating in space image 3 by an operating object such as a user's finger. The aerial operation detection sensor 1351 senses, for example, an area that overlaps with the entire display area of ​​the floating in space image 3. Note that the aerial operation detection sensor 1351 may only sense an area that overlaps with at least a portion of the display area of ​​the floating in space image 3.

[0046] Specific examples of the aerial operation detection sensor 1351 include a distance sensor that uses invisible light such as infrared light, an invisible laser, ultrasonic waves, etc. The aerial operation detection sensor 1351 may also be configured to detect coordinates on a two-dimensional plane by combining multiple sensors. The aerial operation detection sensor 1351 may also be configured with a ToF (Time of Flight) LiDAR (Light Detection and Ranging) or an image sensor.

[0047] The mid-air operation detection sensor 1351 only needs to be capable of sensing to detect touch operations with the user's finger on objects displayed as the floating-in-space image 3. Such sensing can be performed using existing technology.

[0048] The aerial operation detection unit 1350 acquires a sensing signal from the aerial operation detection sensor 1351, and, based on the sensing signal, determines whether or not the user's finger has made contact with an object in the floating in space image 3, and calculates the position (contact position) where the user's finger has made contact with the object. The aerial operation detection unit 1350 is configured, for example, by a circuit such as an FPGA (Field Programmable Gate Array). Furthermore, some of the functions of the aerial operation detection unit 1350 may be realized by software, for example, by a program for detecting aerial operation executed by the control unit 1110 or the image control unit 1160. The aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be configured as an integrated unit. The aerial operation detection unit 1350 and the control unit 1110 or the image control unit 1160 may be configured as an integrated unit.

[0049] The aerial operation detection sensor 1351 and the aerial operation detection unit 1350 may be configured to be built into the space-floating image display device 1000, or may be provided externally as a separate entity from the space-floating image display device 1000. When provided as a separate entity from the space-floating image display device 1000, the aerial operation detection sensor 1351 and the aerial operation detection unit 1350 are configured to be able to transmit information and signals to the space-floating image display device 1000 via a wired or wireless communication connection path or a video signal transmission path. This makes it possible to build a system in which the space-floating image display device 1000, which does not have aerial operation detection function, is used as the main body, and only the aerial operation detection function can be added as an option.

[0050] Also, the aerial operation detection sensor 1351 may be a separate unit, and the aerial operation detection unit 1350 may be built into the space-floating image display device 1000. In cases where it is desired to more freely arrange the aerial operation detection sensor 1351 relative to the installation position of the space-floating image display device 1000, there is an advantage to a configuration in which only the aerial operation detection sensor 1351 is a separate unit.

[0051] The imaging unit 1180 is a camera with an image sensor, and captures images of the space near the space-floating image 3 and / or the face, arms, fingers, etc. of the user 230. A plurality of imaging units 1180 may be provided. For example, the imaging unit 1180 may be provided as a stereo camera. By using a plurality of imaging units 1180, or by using an imaging unit with a depth sensor, the mid-air operation detection unit 1350 can be assisted in detecting the touch operation of the space-floating image 3 by the user 230. The imaging unit 1180 may be provided separately from the space-floating image display device 1000. When the imaging unit 1180 is provided separately from the space-floating image display device 1000, it is sufficient to configure it so that an imaging signal can be transmitted to the space-floating image display device 1000 via a wired or wireless communication connection path, etc.

[0052] For example, if the aerial operation detection sensor 1351 is configured as an object intrusion sensor that targets a plane (intrusion detection plane) including the display surface (display range) of the spatial floating image 3 and detects whether or not an object has intruded into this intrusion detection plane, the aerial operation detection sensor 1351 may not be able to detect information such as how far an object (e.g., a user's finger) that has not intruded into the intrusion detection plane is from the intrusion detection plane, or how close the object is to the intrusion detection plane.

[0053] In such a case, the distance between the object and the intrusion detection plane (space floating image 3) can be calculated by using information such as object depth calculation information based on captured images from the multiple imaging units 1180 and object depth information from a depth sensor. Then, various information such as this depth calculation information, depth information, and distance between the object and the intrusion detection plane is used for various display controls for the space floating image 3.

[0054] Furthermore, without using the aerial operation detection sensor 1351, the aerial operation detection unit 1350 may detect a touch operation on the floating-in-space image 3 by the user 230 based on the captured image of the imaging unit 1180. In this case, the imaging unit 1180 may be referred to as an aerial operation detection sensor.

[0055] Furthermore, the imaging unit 1180 may capture an image of the face of the user operating the space-floating image 3, and the control unit 1110 or the like may perform a process to identify the user. Furthermore, in order to determine whether or not there is another person standing around or behind the user operating the space-floating image 3 and peeking at the user's operation of the space-floating image 3, the imaging unit 1180 may capture an image of the user operating the space-floating image 3 and a range including the user's surrounding area.

[0056] The operation input unit 1107 is, for example, an operation button, a signal receiving unit such as a remote controller, or an infrared light receiving unit, and inputs signals for operations different from the user's air operation (touch operation). Apart from the above-mentioned user who touches the space floating image 3, the operation input unit 1107 may also be used by, for example, an administrator to operate the space floating image display device 1000.

[0057] The video signal input unit 1131 is connected to an external video output device and inputs video data (video signals). The video signal input unit 1131 can be implemented using various digital video input interfaces. For example, it may be configured with a video input interface conforming to the HDMI (registered trademark) (High-Definition Multimedia Interface) standard, a video input interface conforming to the DVI (Digital Visual Interface) standard, or a video input interface conforming to the DisplayPort standard. Alternatively, an analog video input interface such as analog RGB or composite video may be provided.

[0058] The audio signal input unit 1133 is connected to an external audio output device and inputs audio data (audio signals). The audio signal input unit 1133 may be configured as an audio input interface conforming to the HDMI standard, an optical digital terminal interface, a coaxial digital terminal interface, or the like. In the case of an interface conforming to the HDMI standard, the video signal input unit 1131 and the audio signal input unit 1133 may be configured as an interface in which a terminal and a cable are integrated.

[0059] The audio output unit 1140 can output audio based on audio data input to the audio signal input unit 1133. The audio output unit 1140 may be configured with a speaker 1140. The audio output unit 1140 may also include a section that performs voice synthesis processing, etc. The audio output unit 1140 may also output built-in operation sounds and error warning sounds. Alternatively, the audio output unit 1140 may be configured to output a digital signal to an external device, like the Audio Return Channel function defined in the HDMI standard.

[0060] The audio input unit 1139 may be configured with a microphone 1139. The microphone 1139 is a microphone that collects sounds around the space-floating image display device 1000, converts them into signals, and generates audio signals. The microphone may record a person's voice, such as a user's voice, and the control unit 1110 or the like performs voice recognition processing on the generated audio signal to obtain text information from the audio signal. The audio input unit 1139 may be provided with a part that performs voice recognition processing or the like. Note that the audio output unit 1140, the audio input unit 1139, etc. may be connected as external devices to the space-floating image display device 1000.

[0061] The nonvolatile memory 1108 stores various data used by the space-floating image display device 1000. The data stored in the nonvolatile memory 1108 includes, for example, data for various operations to be displayed on the space-floating image 3, display icons, data of objects for the user to operate, layout information, etc. The memory 1109 stores image data to be displayed as the space-floating image 3, data for controlling the device, etc.

[0062] The control unit 1110 includes a processor and controls the operation of each unit connected to it. The control unit 1110 may also work in conjunction with a program stored in the memory 1109 to perform calculations based on information acquired from each unit in the space floating image display device 1000.

[0063] 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.

[0064] The removable media interface 1134 is an interface for connecting a removable recording medium (removable media). The removable recording medium (removable media) may be composed of a semiconductor device memory such as a solid state drive (SSD), a magnetic recording medium recording device such as a hard disk drive (HDD), or an optical recording medium such as an optical disk. The removable media interface 1134 can read various information such as video data, image data, and audio data recorded on the removable recording medium. The video data, image data, etc. recorded on the removable recording medium are output as the floating image 3 via the video display unit 1102 and the retroreflection unit 1101.

[0065] 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.

[0066] The video data, image data, etc. recorded in the storage unit 1170 are output as the space floating image 3 via the video display unit 1102 and the retroreflection unit 1101 based on processing by the video control unit 1160. Video data, image data, etc. of display icons, objects for user operation, etc. displayed as the space floating image 3 are also recorded in the storage unit 1170. Layout information of the display icons, objects, etc. displayed as the space floating image 3, and various metadata information related to the objects, etc. are also recorded in the storage unit 1170.

[0067] The audio data recorded in the storage unit 1170 is output as audio from the audio output unit 1140, for example.

[0068] The video control unit 1160 performs various controls related to the video signal input to the video display unit 1102. Based on the video signal (video data), the video control unit 1160 creates a video signal (display data) for displaying a video on the video display unit 1102 (for example, the liquid crystal display panel 11 of the display device 1 described above), and supplies the video signal to the video display unit 1102. The video control unit 1160 may be referred to as a video processing circuit, and may be configured with hardware such as an ASIC, FPGA, or video processor. The video control unit 1160 may also be referred to as a video processing unit or an image processing unit. The video control unit 1160 performs video switching control, such as determining which video signal to input to the video display unit 1102, between the video signal to be stored in the memory 1109 and the video signal (video data) input to the video signal input unit 1131.

[0069] Note that the control unit 1110 may perform the same processing as the video control unit 1160, in which case the control unit 1110 may be referred to as a video processing unit, etc. At least one of the control unit 1110, the video control unit 1160, the aerial operation detection unit 1360, etc. may perform unique control processing, in which case the control unit 1110, the video control unit 1160, the aerial operation detection unit 1360, etc. may be referred to as a video processing unit.

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

[0071] Furthermore, the video control unit 1160 may control image processing of the video signal input from the video signal input unit 1131, the video signal to be stored in the memory 1109, etc. Examples of image processing include scaling processing to enlarge, reduce, deform, etc. the image, brightness adjustment processing to change the brightness, contrast adjustment processing to change the contrast curve of the image, and Retinex processing to decompose the image into light components and change the weighting of each component.

[0072] Furthermore, the video control unit 1160 may perform special effect video processing or the like to assist the user's mid-air operation (touch operation) on the video signal input to the video display unit 1102. The special effect video processing is performed, for example, based on the detection result of the user's touch operation by the mid-air operation detection unit 1350, or on the image of the user captured by the imaging unit 1180. Furthermore, the video control unit 1160 or the like may perform audio control processing when audio is output from the audio output unit 1140 simultaneously with the floating-in-space video 3. An audio control unit for this audio control processing may be provided separately from the video control unit 1160.

[0073] The attitude sensor 1113 is a sensor configured by a gravity sensor or an acceleration sensor, or a combination of these, and can detect the attitude in which the space-floating image display device 1000 is installed. Based on the attitude detection result of the attitude sensor 1113, the control unit 1110 may control the operation of each connected unit. For example, when an undesirable attitude in the user's usage state is detected, the control unit 1110 may perform control such that the image being displayed on the image display unit 1102 is stopped and an error message is displayed to the user. Alternatively, when the attitude sensor 1113 detects a change in the installation attitude of the space-floating image display device 1000, the control unit 1110 may perform control such that the display direction of the image being displayed on the image display unit 1102 is rotated.

[0074] As explained above, various functions are installed in the space-floating image display device 1000. However, the space-floating image display device 1000 does not need to have all of these functions, and any configuration is acceptable as long as it has the function of forming the space-floating image 3.

[0075] <Configuration example of a space floating image display device> Next, a configuration example of the space-floating image display device will be described. The layout of the components of the space-floating image display device according to this embodiment can be various depending on the usage form. Below, the layouts of each of Figs. 4A to 4C will be described. In addition, in each example of Figs. 4A to 4C, the thick lines surrounding the components (display device 1, etc.) of the space-floating image display device 1000 show an example of the housing structure of the space-floating image display device 1000 (housing 1190 in Fig. 3).

[0076] FIG. 4A is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 of FIG. 4A is a space-floating image display device that employs the optical system of FIG. 2A. In the space-floating image display device 1000 of FIG. 4A, image light transmitted through a transparent member 100 is focused in the air as a space-floating image 3. Furthermore, using sensing light from an aerial operation detection sensor 1351 arranged on the far side of the transparent member 100 as seen from the user, it is possible to detect operation of the space-floating image 3 by the user's finger 9004. Note that the x direction is the left-right direction as seen from the user, the y direction is the front-back direction (depth direction) as seen from the user, and the z direction is the up-down direction (vertical direction). The definitions of the x direction, y direction, and z direction are the same in each of the figures from FIG. 4A onwards, so repeated explanations will be omitted.

[0077] In the example of the floating-in-space image display device that employs the optical system of FIG. 2A, the floating-in-space image 3 is formed in front of the transparent member 100, and the operation of the floating-in-space image 3 by the user's finger can be detected using the sensing light of the mid-air operation detection sensor 1351 that is located on the back side of the transparent member 100 as seen from the user.

[0078] Next, Fig. 4B is a diagram showing an example of the configuration of a space-floating image display device. Fig. 4B is a diagram showing the configuration of the internal optical system of the space-floating image display device 1000 of Fig. 4A. The space-floating image display device 1000 shown in Fig. 4B is equipped with an optical system corresponding to the optical system of Fig. 2A. The space-floating image display device 1000 shown in Fig. 4B is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward.

[0079] 4B, the space-floating image display device 1000 has a transparent member 100 installed on the top surface of the device. The space-floating image 3 is formed above the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is provided as shown in the figure, it can detect the operation of the space-floating image 3 by the finger of the user 230.

[0080] In addition, in FIG. 4B, the display device 1 and the space floating image 3 are in a plane-symmetrical relationship with the surface of the retroreflector 5 as the reference.

[0081] FIG. 4C is a diagram showing an example of the configuration of a space-floating image display device. The space-floating image display device 1000 shown in FIG. 4C is equipped with an optical system corresponding to the optical system of FIG. 2A. The space-floating image display device 1000 shown in FIG. 4C is installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000 (toward the user 230). That is, in FIG. 4C, the space-floating image display device 1000 is installed with the transparent member 100 facing the front of the device (toward the user 230). The space-floating image 3 is formed on the user 230 side of the surface of the transparent member 100 of the space-floating image display device 1000. The light of the space-floating image 3 travels diagonally upward. If the mid-air operation detection sensor 1351 is provided as shown in FIG. 4C, it can detect the operation of the space-floating image 3 by the finger of the user 230. 4C , the aerial operation detection sensor 1351 senses the finger of the user 230 from above, and can utilize the reflection of sensing light by the nail of the user 230 for touch detection. Generally, a nail has a higher reflectivity than the pad of a finger, so configuring the aerial operation detection sensor 1351 in this way can improve the accuracy of touch detection.

[0082] According to the configuration of the space-floating image display device of FIGS. 4A to 4C, it is possible to realize a user-friendly space-floating image display device using the optical system of FIG. 2A.

[0083] <Display device> Next, the display device 1 of this embodiment will be described with reference to the drawings. The display device 1 of this embodiment includes a liquid crystal display panel 11 as an image display element 11, and a light source device 13 that constitutes a light source for the liquid crystal display panel 11. In Fig. 5, the light source device 13 is shown together with the liquid crystal display panel 11 as an exploded perspective view.

[0084] As shown by arrow 30 in Fig. 5, the image display element 11, which is a liquid crystal display panel, receives an illumination light beam from a light source device 13, which is a backlight device, that has narrow-angle diffusion characteristics, i.e., has strong directionality (in other words, linearity) and characteristics similar to laser light with a polarization plane aligned in one direction. The image display element 11, which is a liquid crystal display panel 11, modulates the received illumination light beam in accordance with an input video signal. The modulated image light is reflected by the retroreflector 2 and passes through a transparent member 100 to form a real image, a floating image (see Fig. 1).

[0085] 5, the display device 1 is configured with a light source device 13 and a liquid crystal display panel 11, a light redirection panel 54 that controls the directional characteristics of the light beam emitted from the light source device 13, and a narrow-angle diffuser (not shown) as needed. Specifically, polarizing plates are provided on both sides of the liquid crystal display panel 11, and as indicated by arrow 30 in FIG. 5, image light of a specific polarization is emitted with its intensity modulated by a video signal. This allows a desired image to be projected as highly directional (linear) light of a specific polarization via the light redirection panel 54 toward the retroreflector 2. After being reflected by the retroreflector 2, the light is transmitted toward the eyes of a monitor outside the store (space) shown in FIG. 1, forming the floating image 3. A protective cover 50 (see FIGS. 6 and 7) may be provided on the surface of the light redirection panel 54.

[0086] <Display device example 1> FIG. 6 shows an example of a specific configuration of the display device 1. In FIG. 6, a liquid crystal display panel 11 and a light direction conversion panel 54 are disposed on the light source device 13 shown in FIG. 5. This light source device 13 is configured by, for example, housing LED elements 201 and a light guide 203 inside a plastic case or the like. As shown in FIG. 5 and other figures, the end surface of the light guide 203 is provided with a lens shape whose cross-sectional area gradually increases toward the light receiving section in order to convert divergent light from each LED element 201 into a substantially parallel beam. The lens shape has an effect of gradually reducing the divergence angle by multiple total reflections during propagation inside. The liquid crystal display panel 11 constituting the display device 1 is attached to the top surface of the display device 1. In addition, an LED substrate 202 mounting the LED elements 201, which are semiconductor light sources, and their control circuits is attached to one side surface of the light source device 13 (the left end surface in this example). A heat sink, which is a member for cooling the heat generated by the LED elements 201 and the control circuit, may be attached to the outer surface of the LED substrate 202.

[0087] The liquid crystal display panel 11 is mounted on the top surface of the case of the light source device 13 through a frame (not shown) for the liquid crystal display panel 11. The frame is also fitted with an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. The liquid crystal display panel 11, which is the image display element 11, generates a display image by modulating the intensity of transmitted light in conjunction with the LED elements 201, which are solid-state light sources, based on a control signal from a control circuit (image control unit 1160 in FIG. 3) constituting the electronic device. The generated image light has a narrow diffusion angle and contains only specific polarization components, resulting in a novel image display device similar to a surface-emitting laser image source driven by a video signal. Currently, it is technically and safety-wise impossible to obtain a laser beam of the same size as the image obtained by the display device 1 described above using a laser device. Therefore, in this embodiment, light similar to the surface-emitting laser image light described above is obtained from a beam of light from a general light source, such as an LED element.

[0088] Next, the configuration of the optical system housed in the case of light source device 13 will be described in detail with reference to Fig. 6 and Fig. 7. Because Fig. 6 and Fig. 7 are cross-sectional views, only one of the multiple LED elements 201 constituting the light source is shown, and this is converted into approximately parallel light (collimated light) by the shape of light-receiving end surface 203a of light guide 203. For this reason, the light-receiving portion of the light guide end surface and LED element 201 are attached while maintaining a predetermined positional relationship.

[0089] Each light guide 203 is formed of a translucent resin such as acrylic. The LED light receiving surface at the end of light guide 203 has a cone-shaped outer periphery obtained by rotating a parabolic cross section, and the top of the light guide 203 has a concave portion with a convex portion (i.e., a convex lens surface) formed in the center, and the center of the flat portion has a convex lens surface (alternatively, a concave lens surface) that protrudes outward (not shown). The outer shape of the light receiving portion of the light guide to which LED element 201 is attached is a parabolic shape that forms a cone-shaped outer periphery, and is set within an angle range that allows total reflection within the light that is emitted from the LED element toward the periphery, or a reflective surface is formed.

[0090] On the other hand, the LED elements 201 are arranged at predetermined positions on the surface of the circuit board, that is, the LED substrate 202. The LED substrate 202 is arranged and fixed so that the LED elements 201 on the surface are positioned in the center of the recessed portion described above with respect to the light-receiving end surface 203a, that is, the LED collimator.

[0091] According to this configuration, the shape of the light-receiving end surface 203a of the light guide 203 makes it possible to extract the light emitted from the LED element 201 as approximately parallel light, thereby improving the efficiency of use of the generated light.

[0092] As described above, the light source device 13 is configured by attaching a light source unit having a plurality of LED elements 201 arranged as light sources to the light-receiving end surface 203a, which is a light-receiving section provided on the end surface of the light guide 203, and the divergent light beams from the LED elements 201 are converted into approximately parallel light by the lens shape of the light-receiving end surface 203a of the light guide 203, which is guided inside the light guide 203 as shown by the arrow, and emitted by the light beam direction conversion means 204 towards the liquid crystal display panel 11, which is arranged approximately parallel to the light guide 203. By optimizing the distribution (in other words, density) of the light beam direction conversion means 204 depending on the shape of the inside or surface of the light guide 203, it is possible to control the uniformity of the light beam incident on the liquid crystal display panel 11.

[0093] The light beam direction conversion means 204 described above emits the light beam propagated inside the light guide 203 toward the liquid crystal display panel 11 disposed approximately parallel to the light guide 203, by using the shape of the surface of the light guide 203 or by providing a portion with a different refractive index inside the light guide 203. At this time, when the liquid crystal display panel 11 is faced directly at the center of the screen and the viewpoint is positioned at the same position as the diagonal dimension of the screen, if the relative brightness ratio between the center of the screen and the periphery of the screen is 20% or more, there is no practical problem, and if it exceeds 30%, it will be an even better characteristic.

[0094] 6 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED element 201 described above. In Fig. 6, light source device 13 is composed of light guide 203 formed of, for example, plastic or the like and having light beam direction conversion means 204 on its surface or inside, LED element 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc. Attached to the top surface of light source device 13 is liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0095] Furthermore, a film- or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects one polarized wave (e.g., P wave) 212 of the natural light beam 210 emitted from the LED element 201. The reflected light is reflected again by a reflective sheet 205 provided on one surface (the lower surface in the figure) of the light guide 203, and directed toward the liquid crystal display panel 11. Therefore, a retardation plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49. The reflected light (reflected light beam) is reflected by the reflective sheet 205 and passes through the retardation plate (λ / 4 plate) twice, thereby converting it from P polarized light to S polarized light. This improves the utilization efficiency of the light source light as image light. The image light beam, the light intensity of which has been modulated by the image signal in the liquid crystal display panel 11, is emitted as shown by the arrow 213 in Fig. 6 and enters the retroreflector 2. After reflection by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0096] 7 is a cross-sectional layout diagram illustrating the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED elements 201, similar to Fig. 6. Light source device 13 is similarly composed of light guide 203 formed of, for example, plastic and having light beam direction conversion means 204 on its surface or inside, LED elements 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc. Attached to the top surface of light source device 13 is liquid crystal display panel 11 that has polarizing plates on the light source light entrance surface and the image light exit surface.

[0097] A film- or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects one polarized wave (e.g., S wave) 211 of the natural light beam 210 emitted from the LED element 201. That is, in the example of FIG. 7, the selective reflection characteristics of the reflective polarizing plate 49 are different from those in FIG. 7. The reflected light is reflected by a reflective sheet 205 provided on one surface (the lower surface in the figure) of the light guide 203 and returns to the liquid crystal display panel 11. A retardation plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49. The reflected light (reflected light beam) is reflected by the reflective sheet 205 and passes through the retardation plate (λ / 4 plate) twice, converting it from S-polarized light to P-polarized light. This improves the utilization efficiency of the light source light as image light. The image light beam, which has been intensity-modulated by the image signal on the liquid crystal display panel 11, is emitted as shown by the arrow 214 in Fig. 7 and enters the retroreflector 2. After being reflected by the retroreflector 2, a real image, a floating image in space, can be obtained.

[0098] In the light source device 13 shown in Figures 6 and 7, in addition to the function of the polarizer provided on the light incident surface of the corresponding liquid crystal display panel 11, a reflective polarizer reflects the polarized light component on one side. Therefore, the theoretically obtainable contrast ratio is the reciprocal of the cross transmittance of the reflective polarizer multiplied by the reciprocal of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel 11. This results in high contrast performance. In fact, experiments have confirmed that the contrast performance of the displayed image is improved by more than 10 times. As a result, high-quality images comparable to those of self-luminous organic EL devices are obtained.

[0099] <Display device example 2> 8 shows another example of the specific configuration of the display device 1. The light source device 13 of this display device 1 is configured by housing LEDs, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and a liquid crystal display panel 11 is attached to the upper surface of the light source device 13. Also, LED elements 201, which are semiconductor light sources, and an LED board 202, on which a control circuit for the LED elements 201 is mounted, are attached to one side of the case of the light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED elements 201 and the control circuit, is attached to the outer surface of the LED board 202.

[0100] The liquid crystal display panel frame attached to the top surface of the case of the light source device 13 is configured to have attached thereto the liquid crystal display panel 11 attached to the frame, and further to have attached thereto an FPC 403 electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light together with the LED elements, which are solid-state light sources, based on a control signal from a control circuit (not shown) that constitutes the electronic device.

[0101] <Display device example 3> Next, another example of the specific configuration of the display device 1 (Example 3 of the display device) will be described with reference to Fig. 9. The light source device of this display device 1 converts a divergent beam of light (a mixture of P-polarized and S-polarized light) from the LED 201 into a substantially parallel beam by a collimator (LED collimator) 18, and reflects the parallel beam toward the liquid crystal display panel 11 by the reflecting surface of the reflective light guide 304. The reflected light is incident on a reflective polarizer 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. The reflective polarizer 49 transmits light of a specific polarization (e.g., P-polarized light) and causes the transmitted polarized light to be incident on the liquid crystal display panel 11. Here, light of polarization other than the specific polarization (e.g., S-polarized light) is reflected by the reflective polarizer 49 and directed toward the reflective light guide 304 again.

[0102] The reflective polarizing plate 49 is installed at an angle with respect to the liquid crystal display panel 11 so that the reflective polarizing plate 49 is not perpendicular to the chief ray of light from the reflective surface of the reflective light guide 304. The chief ray of the light reflected by the reflective polarizing plate 49 is incident on the transmission surface of the reflective light guide 304. The light that has entered the transmission surface of the reflective light guide 304 passes through the back surface of the reflective light guide 304, passes through the λ / 4 plate 270 which is a retardation plate, and is reflected by the reflector 271. The light reflected by the reflector 271 passes through the λ / 4 plate 270 again, and passes through the transmission surface of the reflective light guide 304. The light that has passed through the transmission surface of the reflective light guide 304 is incident on the reflective polarizing plate 49 again.

[0103] At this time, the light that re-enters the reflective polarizer 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarization (for example, P-polarized light) that is transmitted through the reflective polarizer 49. Therefore, the light whose polarization has been converted passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Note that with regard to the polarization design related to the polarization conversion, the polarization may be configured in reverse from the above explanation (S-polarized light and P-polarized light may be reversed).

[0104] As a result, the light from the LED 201 is aligned to a specific polarization (for example, P polarization), enters the liquid crystal display panel 11, and is brightness-modulated in accordance with the video signal to display an image on the panel surface. As in the above example, there are multiple LEDs 201 that constitute the light source, and these are attached to predetermined positions relative to the corresponding collimators 18 of the multiple collimators 18. However, since Figure 9 is a vertical cross section, only one LED 201 and one collimator 18 are shown.

[0105] Each of the collimators 18 is formed of, for example, a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer peripheral surface obtained by rotating a parabolic cross section. The collimator 18 may have a concave portion with a convex portion (i.e., a convex lens surface) formed in the center of the apex (the side facing the LED substrate 202) of the collimator 18. The collimator 18 may have a convex lens surface protruding outward (or a concave lens surface recessed inward) in the center of the flat portion (the side opposite the apex). The parabolic surface forming the cone-shaped outer peripheral surface of the collimator 18 is set within an angle range that allows the light emitted from the LED 201 in the peripheral direction to be totally reflected therein, or a reflective surface is formed therein.

[0106] The LEDs 201 are arranged at predetermined positions on the surface of the LED substrate 202, which is the circuit board. The LED substrate 202 is arranged and fixed to the collimator 18 so that the LEDs 201 on the surface are positioned at the center of the apex of the conical convex shape (or in the concave portion if the apex has a concave portion).

[0107] With this configuration, the collimator 18 focuses the light emitted from the LED 201, particularly the light emitted from the central portion, into parallel light by the convex lens surface that forms the outer shape of the collimator 18. Light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the cone shape of the collimator 18, and is similarly focused into parallel light. In other words, the collimator 18, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract almost all of the light generated by the LED 201 as parallel light, thereby improving the utilization efficiency of the generated light.

[0108] Furthermore, the light converted into approximately parallel light by the collimator 18 shown in FIG. 9 is reflected by the reflective light guide 304. Due to the action of the reflective polarizer 49, light of a specific polarization of the light is transmitted through the reflective polarizer 49, while light of the other polarization reflected by the reflective polarizer 49 is transmitted again through the light guide 304. The light is reflected by the reflector 271, which is located opposite the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarized and converted twice by passing through the λ / 4 plate 270, which is a retardation plate. The light reflected by the reflector 271 is transmitted again through the light guide 304 and enters the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarization-converted, it is transmitted through the reflective polarizer 49 and enters the liquid crystal display panel 11 with its polarization direction aligned. As a result, all of the light from the light source can be utilized, thereby doubling the geometrical optical utilization efficiency of light. Furthermore, since the degree of polarization (extinction ratio) of the reflective polarizer 49 is also included in the extinction ratio of the entire system, the use of the light source device of this embodiment significantly improves the contrast ratio of the entire display device. Note that the reflection diffusion angle of light at each reflective surface can be adjusted by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 can be adjusted for each design to optimize the uniformity of the light incident on the liquid crystal display panel 11.

[0109] It should be noted that the λ / 4 plate 270, which is the retardation plate in Fig. 9, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270. In the configuration of Fig. 9, any retardation plate may be used as long as the phase changes by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarized light.

[0110] <Display device example 4> Furthermore, another example (display device example 4) of the configuration of the optical system such as the light source device of display device 1 will be described with reference to FIG. 10 . Display device example 4 is a configuration example in which a diffusion sheet is used instead of reflective light guide 304 in the light source device of display device example 3. Specifically, two optical sheets (in other words, diffusion sheets) that convert the diffusion characteristics in the vertical and horizontal directions of the drawing (front and back directions in the drawing, not shown) are used on the light emission side of collimator 18. The two optical sheets are shown as optical sheet 207A and optical sheet 207B. Light from collimator 18 is made to enter between the two optical sheets.

[0111] The optical sheet may be a single sheet instead of a two-sheet configuration. In the case of a single sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes on the front and back surfaces of the single optical sheet. Alternatively, multiple diffusion sheets may be used to share the functions. In the example of FIG. 10 , the reflection and diffusion characteristics due to the front and back shapes of optical sheets 207A and 207B may be optimally designed using the number of LEDs 201, the divergence angle from LED substrate 202, and the optical specifications of collimator 18 as design parameters so that the surface density of the light beam emitted from liquid crystal display panel 11 is uniform. In other words, in the example of FIG. 10 , the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of the light guide.

[0112] In the example of FIG. 10, polarization conversion is performed in the same manner as in the display device example 3 described above. That is, in the example of FIG. 10, reflective polarizing plate 49 may be configured to have the property of reflecting S-polarized light (transmitting P-polarized light). In this case, the reflective polarizing plate 49 transmits P-polarized light out of the light emitted from LED 201, which is the light source, and the transmitted light enters liquid crystal display panel 11. The reflective polarizing plate 49 reflects S-polarized light out of the light emitted from LED 201, which is the light source, and the reflected light passes through retardation plate 270 shown in FIG. 10. The light that passes through retardation plate 270 is reflected by reflector 271. The light reflected by reflector 271 passes through retardation plate 270 again and is converted to P-polarized light. The polarization-converted light passes through reflective polarizing plate 49 and enters liquid crystal display panel 11.

[0113] It should be noted that the λ / 4 plate 270, which is the retarder in FIG. 10, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270. In the configuration of FIG. 10, any retarder that changes the phase by 90° (λ / 2) when polarized light passes through it twice will suffice. The thickness of the retarder may be adjusted according to the distribution of incident angles of the polarized light. It should be noted that in FIG. 10 as well, the polarization design for polarization conversion may be configured in reverse (reversing the S-polarized light and P-polarized light) from the above explanation.

[0114] In a typical TV device, the light emitted from the LCD panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown by the X-axis in FIG. 12(a)) and the vertical direction of the screen (shown by the Y-axis in FIG. 12(b)). In contrast, the diffusion characteristics of the light beam emitted from the LCD panel 11 of this embodiment are 1 / 5 of the 62-degree viewing angle of a typical TV device, as shown in Example 1 of FIG. 12, when the viewing angle at which the luminance is 50% of that at a front view (angle of 0 degrees) is set to 13 degrees. Similarly, the vertical viewing angle is asymmetric between the top and bottom, and the reflection angle and the area of ​​the reflective surface of the reflective light guide are optimized to keep the upper viewing angle to about 1 / 3 of the lower viewing angle. As a result, the amount of image light directed toward the monitoring direction is significantly improved compared to conventional LCD TVs, with brightness being more than 50 times higher.

[0115] Furthermore, assuming the viewing angle characteristics shown in Example 2 in Figure 12, if the viewing angle at which brightness is 50% of that when viewed from the front (angle of 0 degrees) is set to 5 degrees, this will be 1 / 12 of the 62 degrees of devices used for general TV applications. Similarly, the vertical viewing angle is optimized by optimizing the reflection angle and the area of ​​the reflective surface of the reflective light guide so that the viewing angle is approximately 1 / 12 of that of devices used for general TV applications, with equal viewing angle both above and below. As a result, the amount of image light directed in the monitoring direction is significantly improved compared to conventional LCD TVs, and brightness is more than 100 times greater.

[0116] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux directed in the monitoring direction can be concentrated, significantly improving the efficiency of light utilization. As a result, even when using a liquid crystal display panel for general TV applications, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create a video display device that is compatible with information display systems facing bright outdoor environments.

[0117] When using a large LCD display panel, the overall brightness of the screen can be improved by directing the light from the periphery of the screen inward so that it is directed toward the observer when the observer is facing the center of the screen. Figure 11 shows the convergence angle between the long and short sides of the panel when the observer's distance from the panel, L, and the panel size (screen ratio 16:10) are used as parameters. When monitoring with the screen in portrait orientation, the convergence angle can be set to match the short side. For example, when using a 22-inch panel in portrait orientation and the monitoring distance is 0.8 m, a convergence angle of 10 degrees will allow the image light from the four corners of the screen to be effectively directed toward the observer.

[0118] Similarly, when monitoring with a 15-inch panel in portrait orientation, if the monitoring distance is 0.8 m, a convergence angle of 7 degrees will allow the image light from the four corners of the screen to be effectively directed towards the monitor. As mentioned above, depending on the size of the LCD panel and whether it is used portrait or landscape, the overall brightness of the screen can be improved by directing the image light from the periphery of the screen towards the monitor who is in the optimum position to monitor the centre of the screen.

[0119] As shown in Figure 9, the basic configuration involves a light source device directing a light beam with a narrow angle of directionality to a liquid crystal display panel 11, which is then luminance-modulated according to a video signal. The video information displayed on the screen of the liquid crystal display panel 11 is then reflected by a retroreflector, and the resulting floating image is displayed indoors or outdoors via a transparent member 100.

[0120] By using the display device and light source device according to the embodiment of the present invention described above, it is possible to realize a space floating image display device with higher light utilization efficiency.

[0121] <Example 2> An example of the internal configuration of a space-floating image display device will be described below as Example 2 of the present invention. Figures 13A and 13B are diagrams showing the configuration of the main part of the space-floating image display device of Example 2.

[0122] 13A and 13B, a space-floating image display device 1000A of Example 2 is an example in which a space-floating image 3 is formed along the surface of the retroreflector 5, in this example, along the xy plane, by image light reflected by the retroreflector 5. The space-floating image display device 1000A shown in FIGS. 13A and 13B is installed horizontally so that the surface on which the space-floating image 3 is formed faces upward, that is, so that the space-floating image 3 is formed above the retroreflector 5. The space-floating image display device 1000A also includes a linear prism sheet 1500. In the example shown in FIG. 13A, the linear prism sheet 1500 is composed of a single linear prism sheet 1501, and in the example shown in FIG. 13B, the linear prism sheet 1500 is composed of two linear prism sheets 1502 and 1503.

[0123] In the space floating image display device 1000A of the second embodiment, the display device 1 and the retroreflector 5 are arranged facing each other. In other words, the display device 1 and the retroreflector 5 are arranged substantially parallel with a predetermined distance between them. Therefore, the display device 1 and the space floating image 3 are in a plane symmetrical relationship with the retroreflector 5 as the reference.

[0124] The display device 1 is configured to include a liquid crystal display panel 11 and a light source device 13. The liquid crystal display panel 11 may be a small liquid crystal display panel with a screen size of, for example, about 5 inches, or a large liquid crystal display panel with a screen size of over 80 inches. The light source device 13 supplies light to the liquid crystal display panel 11 and generates light of a specific polarization having narrow-angle diffusion characteristics. The retroreflector 5 is configured from a corner reflector array, as in Example 1 (see FIG. 2B, etc.).

[0125] As described above, the display device 1 and the retroreflector 5 are disposed facing each other, and therefore the traveling direction of the light beam (image light) emitted from the display device 1 is approximately perpendicular to the surface of the retroreflector 5. However, in the space floating image display device 1000A of the second embodiment, a linear prism sheet 1500 is provided so that the image light emitted from the display device 1 is incident at a predetermined angle with respect to the surface of the retroreflector 5. The linear prism sheet 1500 is an example of a light beam direction changing sheet, and may also be expressed as a light beam direction changing member.

[0126] As explained in the first embodiment, the incident angle α1 of the incident image light on the retroreflector 5 needs to be within the range of 45°±15°, and when the incident angle α1 is 45°, the reflectivity of the incident image light on the retroreflector 5 becomes the highest. For this reason, in the space floating image display device 1000A of the second embodiment, a prism sheet 1500 for changing the traveling direction of the light beam emitted from the display device 1 is provided between the display device 1 and the retroreflector 5 so that the incident angle α1 of the incident image light on the retroreflector 5 is within the range of 45°±15°.

[0127] 13B, two linear prism sheets 1502 and 1503 change the traveling direction of the image light emitted from the display device 1, so that the incident angle α1 of the image light with respect to the retroreflector 5 is 45°±15°. In other words, the two linear prism sheets 1502 and 1503 are disposed between the display device 1 and the retroreflector 5 so that the incident angle α1 of the image light with respect to the retroreflector 5 is 45°±15°. Furthermore, due to the optical properties of the retroreflector 5, the exit angle α2 of the image light emitted from the retroreflector 5 matches the incident angle α1.

[0128] The image light incident on the retroreflector 5 at an incident angle α1 is reflected by the retroreflector 5 and travels obliquely upward at an exit angle α2, forming a floating image 3 on the user side of the retroreflector 5.

[0129] As described above, the display device 1 and the space-floating image 3 are in a plane-symmetrical relationship with respect to the surface of the retroreflector 5. Therefore, the space-floating image 3 is formed along the surface of the retroreflector 5. At this time, the image light emitted from the retroreflector 5 generates the space-floating image 3 at an angle α2 with respect to the xy plane. In other words, a viewer (user) can clearly view the space-floating image 3 by viewing the space-floating image 3 at an angle α2 in the direction of arrow A.

[0130] In Figures 13A and 13B, multiple solid arrows indicate image light that enters the retroreflector 5 from the liquid crystal display panel 11, and multiple dotted arrows indicate image light that exits the retroreflector 5 and generates the spatial floating image 3.

[0131] In addition, an image light control sheet 335 is disposed between the linear prism sheet 1500 and the retroreflector 5. Providing this image light control sheet 335 can improve the user's visibility of the spatial floating image 3. The structures of the linear prism sheet 1500 and the image light control sheet 335 will be described in detail later.

[0132] Here, the linear prism sheet 1500 is disposed close to the liquid crystal display panel (also simply referred to as the "display panel") 11 of the display device 1. The linear prism sheet 1500 is preferably disposed as close as possible to the liquid crystal display panel 11 without coming into contact with the liquid crystal display panel 11. More specifically, the linear prism sheet 1500 is preferably disposed close to the liquid crystal display panel 11 so that the distance La between the linear prism sheet 1500 and the liquid crystal display panel 11 is equal to or less than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0133] 13A, the linear prism sheet 1501 is disposed close to the liquid crystal display panel 11 so that the distance La between the linear prism sheet 1501 and the liquid crystal display panel 11 is equal to or less than ¼ of the distance Lb between the liquid crystal display panel 11 and the retroreflector 5. In addition, in the example shown in Fig. 13B, the linear prism sheets 1502 and 1503 are disposed close to the liquid crystal display panel 11 so that the distance La is equal to or less than ¼ of the distance Lb.

[0134] The image light control sheet 335, together with the linear prism sheet 1500, is also disposed close to the liquid crystal display panel 11. The image light control sheet 335 is preferably disposed as close as possible to the linear prism sheet 1500 without coming into contact with the linear prism sheet 1500. More specifically, the image light control sheet 335 is preferably disposed close to the linear prism sheet 1500 so that the distance Lc between the image light control sheet 335 and the liquid crystal display panel 11 is equal to or less than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5. However, the image light control sheet 335 does not necessarily have to be close to the liquid crystal display panel 11. For example, the distance Lc between the image light control sheet 335 and the liquid crystal display panel 11 may be greater than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0135] 13A, the distance La between the linear prism sheet 1500 and the liquid crystal display panel 11 refers to the distance between the surface of the linear prism sheet 1501 facing the retroreflector 5 and the surface of the liquid crystal display panel 11 facing the retroreflector 5. In the example shown in FIG. 13B, the distance La between the linear prism sheet 1500 and the liquid crystal display panel 11 refers to the distance between the surface of the linear prism sheet 1503 facing the retroreflector 5 and the surface of the liquid crystal display panel 11 facing the retroreflector 5. In this example, the distance Lc between the image light control sheet 335 and the liquid crystal display panel 11 refers to the distance between the surface of the image light control sheet 335 facing the retroreflector 5 and the surface of the liquid crystal display panel 11 facing the retroreflector 5.

[0136] In this way, in the space-floating image display device 1000A of the second embodiment, the linear prism sheet 1500 is arranged close to the liquid crystal display panel 11, and further the image light control sheet 335 is arranged close to the liquid crystal display panel 11, thereby realizing a thin device. Furthermore, the space-floating image device 1000A of the second embodiment is suitable for a viewer (user) to observe the space-floating image 3 from diagonally above in the direction of arrow A, and the visibility of the space-floating image 3 for the user can be improved.

[0137] In the example shown in Figures 13A and 13B, the space-floating image display device 1000A is installed so that the surfaces of the display device 1 and the retroreflector 5 face upward (z direction), but the installation direction of the space-floating image display device 1000A is not limited to this.

[0138] 14A and 14B, the space-floating image display device 1000A may be installed vertically so that the surface on which the space-floating image 3 is formed faces the front of the space-floating image display device 1000A, that is, facing the user 230. In other words, the space-floating image display device 1000A may be installed vertically so that the display device 1 and the retroreflector 5 are aligned vertically, in this example, along the xz plane. The device shown in FIG. 14A is the device shown in FIG. 13A placed vertically, and the linear prism sheet 1500 is composed of a single linear prism sheet 1501. The device shown in FIG. 14B is the device shown in FIG. 13B placed vertically, and the linear prism sheet 1500 is composed of two linear prism sheets 1502 and 1503.

[0139] 14A and 14B, the linear prism sheet 1500 changes the traveling direction of the image light emitted in the y direction (horizontal direction) from the liquid crystal display panel 11 to a diagonally downward direction. Moreover, the image light reflected by the retroreflector 5 travels diagonally upward, and the floating image 3 is displayed outside the retroreflector 5 (on the user 230 side).

[0140] Furthermore, when the space-floating image display device 1000A is placed vertically, it is preferable that the space-floating image 3 is formed at a position lower than the eye height of the user 230. The space-floating image display device 1000A is preferably placed on the floor, for example, so that the user 230's line of sight when looking at the space-floating image 3 while standing is directed diagonally downward. In the space-floating image display device 1000A shown in FIGS. 14A and 14B, the light forming the space-floating image 3 travels diagonally upward, so by forming the space-floating image 3 at the above height, the user 230 can easily view the space-floating image 3 and can also easily operate the space-floating image 3 with their fingers. For example, the space-floating image 3 can be easily applied as a push button on equipment such as a traffic light or elevator.

[0141] Even when the space floating image display device 1000A is placed vertically, the linear prism sheet 1500 is placed close to the liquid crystal display panel 11 of the display device 1. In particular, as shown in Figures 14A and 14B, the linear prism sheet 1500 is preferably placed close to the liquid crystal display panel 11 so that the distance La between the liquid crystal display panel 11 and the linear prism sheet 1500 is equal to or less than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0142] Furthermore, the image light control sheet 335 is preferably disposed close to the liquid crystal display panel 11 together with the linear prism sheet 1500. More specifically, as shown in Figures 14A and 14B, the image light control sheet 335 is preferably disposed close to the linear prism sheet 1500 so that the distance Lc between the image light control sheet 335 and the liquid crystal display panel 11 is equal to or less than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0143] 15 to 18 are enlarged views of the space floating image display device shown in FIG. 14B, and are diagrams for explaining the linear prism sheet and the image light control sheet. The linear prism sheet and the image light control sheet will be described in more detail below with reference to these FIGS.

[0144] 15 and 16, an uneven portion 1506 including convex portions 1504 and concave portions (grooves) 1505 is formed on the surfaces of the linear prism sheets 1502 and 1503 facing the liquid crystal display panel 11. In this example, the convex portions 1504 and the concave portions 1505 are each provided continuously along the x direction and alternately arranged along the y direction. In other words, the surface of the linear prism sheet 1500 facing the liquid crystal display panel 11 is formed in a zigzag shape with a first surface 1507 along the xy plane and a second surface 1508 inclined relative to the first surface 1507.

[0145] Linear prism sheets 1502 and 1503 are commercially available and generally available, with a thickness of approximately 2 mm (millimeters) to 3 mm, and a tilt angle θd of second surface 1508 of approximately 10° to 30°. The pitch (so-called prism pitch) P1 of multiple grooves 1505 is approximately 1 mm.

[0146] The image light is refracted by passing it through linear prism sheets 1502 and 1503 having such a shape. The chief ray of the image light that enters linear prism sheets 1502 and 1503 from second surface 1508 exits linear prism sheets 1502 and 1503 at a constant refraction angle (which can also be referred to as the exit angle).

[0147] 16, image light Li emitted from the liquid crystal display panel 11 along the xy plane is incident on the surface of the linear prism sheet 1502 on the concave-convex portion 1506 side. The image light Li is incident on the linear prism sheet 1502 mainly from the second surface 1508 that forms the bottom surface of the concave portion 1505, and is refracted at a predetermined refraction angle θ1 with respect to the xy plane. The image light Li that has passed through the linear prism sheet 1502 is emitted from the surface of the linear prism sheet 1502 on the retroreflector 5 side at a predetermined refraction angle θ2 (>θ1).

[0148] Here, the linear prism sheets 1501-1503 are made of a resin such as acrylic or polycarbonate. The refraction angles θ1 and θ2 are determined by the refractive index of the resin material, for example, a refractive index of 1.49, and the inclination angle θd of the second surface 1508. Due to restrictions on processing accuracy imposed by the material, the refraction angle θ2 when the image light Li is emitted from the linear prism sheets 1501-1503 is generally around 20°, but is not particularly limited to this.

[0149] Furthermore, the image light Li emitted from the linear prism sheet 1502 is incident on the second linear prism sheet 1503 mainly from the second surface 1508. At this time, the image light Li is incident on the prism sheet 1503 at a predetermined refraction angle θ3 (>θ2) with respect to the xy plane. The image light Li that has passed through the linear prism sheet 1503 is emitted from the surface of the linear prism sheet 1503 facing the retroreflector 5 at a predetermined refraction angle θ4 (>θ3). In other words, the image light Li that has passed through the linear prism sheets 1502 and 1503 is emitted from the linear prism sheet 1503 at a predetermined emission angle ψ (=θ4).

[0150] Here, the refraction angle θ4 (output angle ψ) is twice the refraction angle θ2, for example, approximately 40°, and the image light Li is incident on the retroreflector 5 at this angle. Therefore, in the example shown in FIG. 14B , the incident angle α1 of the image light on the retroreflector 5 is 90°-40°=50°, which satisfies the condition that the incident angle α1 of the image light on the retroreflector 5 is within the range of 45°±15°. Note that in order to set the incident angle α1 of the image light on the retroreflector 5 to 45°, the linear prism sheets 1502 and 1503 may be designed so that the refraction angle θ2=22.5°.

[0151] 15 and 16, the image light Li emitted from a predetermined (arbitrary) point on the liquid crystal display panel 11 diverges at a predetermined divergence angle φa while traveling toward the linear prism sheet 1502, and the spreading width (which can also be called the "diameter of the image light Li") Wa of the image light Li increases as it approaches the linear prism sheet 1502. Then, the image light Li emitted from the predetermined point on the liquid crystal display panel 11 is incident on the linear prism sheet 1502 with a predetermined spreading width Wa1.

[0152] As described above, each of the linear prism sheets 1501 to 1503 is disposed close to the liquid crystal display panel 11, so that the spreading width Wa1 of the image light Li when it enters the linear prism sheets 1501 to 1503 is relatively narrow. The spreading width Wa1 of the image light Li is not particularly limited, but is preferably narrower than a preset set width.

[0153] Specifically, it is preferable that the spreading width Wa1 of the image light Li is narrower than three times the pitch P1. For example, as shown in Fig. 15, it is preferable that the spreading width Wa1 (Wa) of the image light Li on the surface of the linear prism sheet 1502 facing the liquid crystal display 11 (in this example, the surface including the vertices of each convex portion 1505) is narrower than three times the pitch P1. Furthermore, it is preferable that the spreading width Wa1 of the image light when incident on the linear prism sheet 1502 is narrower than the pitch P1, as shown in Fig. 16, for example.

[0154] In other words, it is preferable that the linear prism sheet 1502 is provided close to the liquid crystal display panel 11 so that the spread width Wa1 of the image light Li when it enters the linear prism sheet 1502 is narrower than three times the pitch P1, and in particular so that the spread width Wa1 is narrower than the pitch P1. In other words, it is preferable that the linear prism sheet 1502 is provided close to the liquid crystal display panel 11 so that the image light Li emitted from a predetermined point on the liquid crystal display panel 11 and diffused enters the linear prism sheet 1502 from the second surface 1508 that forms the bottom surface of the recess 1505.

[0155] Similarly, it is preferable that the linear prism sheet 1503 is arranged close to the linear prism sheet 1502 so that the spreading width Wa1 of the image light Li when it enters the linear prism sheet 1503 is narrower than three times the pitch P1, and in particular so that the spreading width Wa1 is narrower than the pitch P1.

[0156] By arranging the linear prism sheet 1500 closely to the surface of the display device 1 in this manner, it becomes easier to increase the incident angle α1 of the image light Li with respect to the retroreflector 5. That is, the image light Li emitted from the display device 1 can be made incident on the retroreflector 5 at an appropriate incident angle α1. Furthermore, the height of the prisms of the linear prism sheet 1500 can be reduced. That is, the thickness of the linear prism sheet 1500 can be reduced. In particular, by arranging multiple linear prism sheets, for example, two linear prism sheets 1502 and 1503, closely to the display device 1, it becomes easier to increase the incident angle α1 of the image light Li with respect to the retroreflector 5.

[0157] In this example, the two linear prism sheets 1502 and 1503 have the same shape, but they may be combined with other linear prism sheets having different shapes. A light-shielding layer may be provided on the first surface (surface along the yz plane) 1507 of the linear prism sheets 1502 and 1503 to block the image light Li from entering the linear prism sheets 1502 and 1503 from the first surface 1507, thereby suppressing the generation of unnecessary light. Furthermore, although the linear prism sheet 1500 included in the space-floating image display device 1000A has been described as being composed of one linear prism sheet 1501 or two linear prism sheets 1502 and 1503, the configuration of the linear prism sheet 1500 is not particularly limited. The linear prism sheet 1500 may be composed of three or more prism sheets as long as it can set the image light Li at a desired incident angle α1.

[0158] 14A and 14B, when a viewer (user) looks down on the space-floating image 3, the image displayed on the display surface of the liquid crystal display panel 11 appears to overlap the space-floating image 3, which may reduce the visibility of the space-floating image 3. Therefore, in the space-floating image display device 1000A of the second embodiment, an image light control sheet 335 is provided on the image light exit surface side of the linear prism sheet 1500.

[0159] This image light control sheet 335 is a member for preventing the image displayed on the liquid crystal display panel 11 from appearing to overlap with the space-floating image 3 when the viewer (user) looks down on the space-floating image 3 in the direction of arrow A, and is provided so as to transmit the chief ray of the image light Li whose traveling direction has been changed by the linear prism sheet 1500. The space-floating image 3 is formed by the image light Li that has passed through this image light control sheet 335. In other words, the image light control sheet 335 functions as a screen for the liquid crystal display panel 11 while transmitting the image light Li.

[0160] 16 and 17, the image light control sheet 335 has a sandwich structure in which light-transmitting portions 336 made of transparent silicon and light-shielding portions 337 made of black silicon of a predetermined thickness are alternately arranged at a predetermined interval, and synthetic resin (not shown) is arranged on the two surfaces through which the image light Li enters and exits. Note that, as the image light control sheet 335, for example, a viewing angle control film (VCF) can be used.

[0161] 16 and 17 , the light-transmitting portions 336 and the light-shielding portions 337 that constitute the image light control sheet 335 are each provided continuously along the x direction and arranged alternately along the z direction (vertical direction). The light-shielding portions 337 function as so-called louvers, and are provided so as to be inclined at a predetermined inclination angle γ with respect to the traveling direction (horizontal direction) of the image light Li emitted from the liquid crystal display panel 11. In other words, the light-shielding portions 337 are provided so as to be inclined at the predetermined inclination angle γ in the same direction as the direction of the chief ray of the image light Li emitted from the linear prism sheet 1503.

[0162] Therefore, the image light Li emitted from the linear prism sheet 1503 passes between the light-shielding portions 337 of the image light control sheet 335. That is, the image light Li emitted from the linear prism sheet 1503 passes through the light-transmitting portions 336. Then, the space-floating image 3 is generated by the image light Li that has passed through the light-transmitting portions 336. On the other hand, when a user looks down at this space-floating image 3 in the direction of arrow A, the image displayed on the liquid crystal display panel 11 is mostly shielded by the light-shielding portions 337 of the image light control sheet 335.

[0163] This prevents the image displayed on the display surface of the liquid crystal display panel 11 from appearing to overlap with the floating image 3 when the user looks down on the floating image 3 in the direction of arrow A, improving the visibility of the floating image 3 for the user.

[0164] 16 and 17 show an example of a configuration in which the image light control sheet 335 has five light-shielding portions 337 (337a to 337e), but the number of light-shielding portions 337 is not particularly limited. The number of light-shielding portions 337 may be six or more, or four or less.

[0165] In the example shown in Figure 16, the image light control sheet 335 is arranged approximately parallel to the linear prism sheet 1500 (1502, 1503), but it is preferable that this image light control sheet 335 be arranged at an angle to the surface of the linear prism sheet 1500, if necessary.

[0166] Here, from the viewpoint of preventing the image displayed on the display surface of the liquid crystal display panel 11 from appearing to overlap with the floating image 3 as described above, it is preferable that the direction of the user's line of sight (direction A) when looking down at the floating image 3 is outside the range of the visible angle β of the image light control sheet 335.

[0167] The visible angle β of the image light control sheet 335 refers to the angle of the visible range between a line segment along the surface of the light-shielding portion 337 (which can also be considered the boundary between the light-transmitting portion 336 and the light-shielding portion 337) and a line segment connecting an end of the light-shielding portion 337 on the image light incident side and an end of the light-shielding portion 337 adjacent thereto on the image light output side. In this example, the visible angle β of the image light control sheet 335 is the angle of the visible range formed by a line segment L1 along the surface of the light-shielding portion 337b and a line segment L2 connecting an end of the light-shielding portion 337b on the image light output side and an end of the light-shielding portion 337c adjacent to the light-shielding portion 337b on the image light output side, as shown in FIG. 17 .

[0168] 17, when the user's line of sight is in the direction of arrow A which forms a predetermined angle θu1 with respect to the xy plane, it is preferable that the angle θu1 be larger than the angle θy of the line segment L2 with respect to the xy plane. In other words, it is preferable that the image light control sheet 335 is disposed so that the angle θy is smaller than the line of sight angle θu1.

[0169] In this way, the image light control sheet 335 is positioned so that the user's line of sight is outside the range of the visible angle β of the image light control sheet 335. This prevents the image displayed on the display surface of the liquid crystal display panel 11 from appearing to overlap with the space floating image 3 when the viewer (user) looks down on the space floating image 3 in the direction of arrow A, thereby improving the visibility of the space floating image 3.

[0170] In the example shown in FIG. 17, since the angle θy is slightly larger than the line-of-sight angle θu1, when the user looks down at the floating image 3, the image displayed on the display surface of the liquid crystal display panel 11 may appear to overlap with the floating image 3.

[0171] Furthermore, from the viewpoint of improving the brightness of the spatial floating image 3, it is preferable that the image light control sheet 335 is arranged so as to easily transmit the chief ray of the image light Li emitted from the linear prism sheet 1503. In other words, it is preferable that the image light control sheet 335 is arranged so as to minimize the obstruction of the passage of the chief ray of the image light Li emitted from the linear prism sheet 1503. Specifically, it is preferable that the image light control sheet 335 is arranged so that the inclination angle γ of the light shielding portion 337 with respect to the xy plane matches the emission angle ψ of the image light Li emitted from the linear prism sheet 1503.

[0172] 15 and 16, the emission angle ψ of the image light Li does not match the tilt angle γ of the light shading portion 337, and the emission angle ψ of the image light Li is slightly larger than the tilt angle γ of the light shading portion 337. Therefore, a part of the image light Li diverging at the divergence angle φa is likely to be blocked by the light shading portion 337, and there is a risk that the spatial floating image 3 will not be sufficiently bright.

[0173] Therefore, based on these viewpoints, it is preferable that the image light control sheet 335 is disposed at an inclination with respect to the surface of the linear prism sheet 1500. As an example, it is preferable that the image light control sheet 335 is disposed at an inclination angle θx with respect to the surface of the linear prism sheet 1503, as shown in Fig. 18. More specifically, it is preferable that the image light control sheet 335 is disposed at an inclination angle θx so that the relationship between the inclination angle θx, the emission angle ψ of the image light Li emitted from the linear prism sheet 1503, and the inclination angle γ of the light blocking portion 337 satisfies the relationship θx = ψ - γ (Condition 1).

[0174] This makes it possible to improve the brightness (luminance) of the space floating image 3, and further improve the visibility of the space floating image 3.

[0175] However, even when the above condition 1 is satisfied, if the divergence angle φa of the image light Li is excessively large, there is a risk that part of the image light Li will be blocked by the light-shielding portion 337. For this reason, it is preferable that the divergence angle φa of the image light Li is large enough so that the image light Li is not blocked by the light-shielding portion 337. Specifically, it is preferable that the emission angle ψ of the image light Li, the divergence angle φa of the image light Li, and the visible angle β of the image light control sheet 335 satisfy the relationship ψ+φa≦β (condition 2). Furthermore, it is preferable that the inclination angle γ of the light-shielding portion 337 and the visible angle β of the image light control sheet 335 satisfy the relationship 2γ≒β (condition 3).

[0176] The above conditions 1 to 3 can be satisfied by appropriately setting the emission angle ψ of the image light Li, the divergence angle φa of the image light Li, the tilt angle θx of the image light control sheet 335, and the tilt angle γ of the light blocking portion 337. As an example, the above conditions 1 to 3 can be satisfied by setting the values ​​of the emission angle ψ, the divergence angle φa, the tilt angle θx, and the tilt angle γ to the values ​​shown in example 1 and example 2 of FIG.

[0177] By satisfying these conditions 1 to 3, when a user looks down on the space floating image 3, it is possible to prevent the image displayed on the display surface of the liquid crystal display panel 11 from appearing to overlap with the space floating image 3, while also improving the brightness of the space floating image 3. As a result, it is possible to further improve the visibility of the space floating image 3 for the user.

[0178] As described above, the configuration of the space-floating image display device 1000A according to the second embodiment allows the device to be made smaller, particularly thinner (for example, thinner in the y-axis direction in FIGS. 14A and 14B), and can be stored in a limited space. Therefore, it is possible to provide a space-floating image display device that has good visibility for the viewer and is also sufficiently high in brightness for practical use.

[0179] Example 3 A space-floating image display device according to a third embodiment of the present invention will be described below. The space-floating image display device houses heat-generating components such as a light source in a housing. Therefore, there is a concern that the lifespan may be shortened due to the temperature rise caused by the heat generated by the components. Therefore, in this embodiment, a technology to solve this problem will be described.

[0180] FIG. 20 shows an example of the configuration of a space-floating image display device according to this embodiment. As shown in FIG. 20, space-floating image display device 2000A houses floating image display unit 2001 and circuit unit 2002 in housing 1190. Housing 1190 contains space S1 housing floating image display unit 2001 and space S2 housing circuit unit 2002, and these spaces are connected in the left-right direction. Therefore, circuit unit 2002 is positioned offset in the left-right direction relative to floating image display unit 2001 when viewed from the front-to-back direction. Housing 1190 also has opening 2003 that transmits image light generated by floating image display unit 2001. Image light from floating image display unit 2001 passes through opening 2003, and a floating image (i.e., a space-floating image, or spatial image 3) is displayed. Note that opening 2003 may be provided with transparent member 100. The floating image display unit 2001 includes, for example, a display device 1 including a light source and a display panel, and a retroreflector 5. Here, the display device 1 may be, for example, a device in which a backlight light source is disposed on the rear side of the display panel. Alternatively, for example, the light source may be a mini LED, and the display device 1 may be a device in which a light source is provided for each pixel. The circuit unit 2002 is configured to have a substrate mounted thereon. For example, the circuit unit 2002 includes a power supply substrate 2021 to which power is supplied, and a signal substrate 2022 that performs signal processing. The circuit unit 2002 may also include a fixing plate 2011 that fixes the power supply substrate 2021 and the signal substrate 2022.

[0181] Components that generate a large amount of heat inside the housing 1190 are, for example, the light source, the power supply board 2021, and the signal board 2022. Here, it is considered that the light source generates the largest amount of heat, followed by the power supply board 2021, and then the signal board 2022. It is also considered that the amount of heat generated by the light source is relatively large compared to the amounts of heat generated by the power supply board 2021 and the signal board 2022. Then, for example, the heat generated by these components increases the temperature of the display panel and circuit components, resulting in a shortened lifespan due to the increased temperature.

[0182] Here, in the space-floating image display device 2000A of this embodiment, the circuit unit 2002 is arranged on the side of the light source, not on the back side, and in front of the light source. Therefore, there is space to the left and right of the light source for the exhaust heat of the light source to escape. Therefore, the space-floating image display device 2000A of this embodiment has a structure that makes it easy to release the exhaust heat of the light source. In addition, the circuit unit 2002 is not easily affected by the exhaust heat of the light source.

[0183] Furthermore, with regard to the power supply substrate 2021 and the signal substrate 2022 of the circuit unit 2002, the signal substrate 2022 may be arranged in the order of proximity to the display device 1 (specifically, the light source), followed by the power supply substrate 2021. That is, it is preferable that the distance between the position of the power supply substrate 2021 and the display device 1 (specifically, the light source) is longer than the distance between the position of the signal substrate 2022 and the display device 1 (specifically, the light source). By separating the power supply substrate 2021, which generates a large amount of heat, from the light source, it is possible to reduce the accumulation of exhaust heat. Furthermore, by separating the power supply substrate 2021, which generates a large amount of heat, from the liquid crystal display panel 11, it is possible to suppress a rise in temperature of the liquid crystal display panel 11.

[0184] Another advantage of the configuration of the space-floating image display device of this embodiment will be described with reference to FIG. 21. FIG. 21 shows the interior of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device as viewed from the front side. In the space-floating image display device 2000A of this embodiment, boards such as a power supply board 2021 and a signal board 2022 are arranged on the side of the floating image display unit 2001 (i.e., the light source, display panel, and retroreflector 5). Therefore, there are no components on the front of the boards, and work can be done from the front side. For example, work such as tightening screws from the front side, removing boards from the front side, and connecting cables to boards can be done from the front side.

[0185] The structure of the space-floating image display device of this embodiment will be described in more detail with reference to FIG. 22. FIG. 22 shows the interior of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device viewed from the top. As described above, the floating image display unit 2001 is housed in space S1, and the circuit unit 2002 is housed in space S2. These spaces (S1, S2) are connected in the left-right direction. As shown in the figure, within the housing 1190, the circuit unit 2002 is positioned so as not to overlap the retroreflector 5 and the display device 1 in the front-to-back direction, and is located behind the retroreflector 5 and in front of the display device 1 in the front-to-back direction. This provides space for dissipating exhaust heat from the light source to the left and right of the light source. In addition, a boss 2031 is provided on the rear side of the display device 1, between the display device 1 and the housing 1190. There is space behind the display device 1 (specifically, the light source), and this space reduces retention of exhaust heat from the light source.

[0186] Next, the relationship with the cable connected to the space floating image display device will be described with reference to Fig. 23. As shown in Fig. 23, the signal board 2022 of the circuit unit 2002 and the mid-air operation detection sensor 1351 that detects the operation of the space floating image 3 by the user 230 are connected by a sensor cable 2024. Here, by placing the sensor cable 2024 in the space on the back side of the display device 1 where the boss 2031 is installed, it is possible to prevent the sensor cable 2024 from being pinched.

[0187] Terminals for connecting cables are provided on the front sides of the power supply board 2021 and the signal board 2022. For example, a terminal 2027 for connecting a power cable 2023 is provided on the front side of the power supply board 2021. The power cable 2023 is connected to this terminal 2027, and power is supplied through the power cable 2023. Furthermore, for example, a terminal 2026 for connecting a signal cable 2025 is provided on the front side of the signal board 2022. The signal cable 2025 is connected to this terminal 2026, and signal data is input and output via the signal cable 2025.

[0188] The space floating image display device 2000A may be provided with a cover 2032 that can cover each terminal provided on the board and the cables connected to each terminal on the front side of the circuit unit 2002. By storing the signal cable 2025 and the power cable 2023 inside the cover 2032 on the front side of the circuit unit 2002, it is possible to avoid false detection by the sensor.

[0189] Furthermore, the terminals of the substrate may be provided so that the cable can be connected from a direction other than the front. In this case, the wiring space in the front-to-rear direction is reduced. The terminals of the substrate may be provided, for example, so that the cable can be connected from the side away from the floating image display unit 2001. For example, as shown in FIG. 23 , the terminals may be configured so that the cable can be connected from the side away from the floating image display unit 2001 (i.e., the side in the left-right direction, the -x-axis direction).

[0190] However, the terminals on the board may be provided so that the cable is connected from the front. In Fig. 23, the terminals are arranged in the -y-axis direction and the cable is connected from the x-axis direction, but for example, a terminal to which a cable can be connected from the front, i.e., from the -y-axis direction, or a terminal facing the -z-axis direction, may be provided so as not to overlap the detection area of ​​the sensor, and the cable may be provided hanging down in the -z-axis direction so as not to overlap the detection area of ​​the sensor.

[0191] An example of cable arrangement will be described with reference to FIGS. 24 and 25. FIG. 24 shows the inside of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device as viewed from the rear side. As shown in FIG. 24, as an example, a plurality of bosses 2031 are provided on the rear side of the display device 1 so as not to interfere with cables extending in the left-right direction on the rear side of the display device 1. Then, by arranging the sensor cable 2024 between the display device 1 and the housing 1190 (i.e., in the space on the rear side of the display device 1), pinching of the sensor cable 2024 can be prevented. For example, the bosses 2031 may not be provided on the lower part inside the housing 1190, and the sensor cable 2024 may be arranged on the lower part inside the housing 1190.

[0192] 24, the connection positions of the signal cable 2025 and the power cable 2023 to the board are shifted in the vertical direction, and the cables are drawn out in the same direction, thereby reducing the clutter of the wiring. Therefore, for example, the positions of the terminals to which the cables are connected may be provided at different positions in the vertical direction (different height positions in the vertical direction). In FIG. 24, the signal cable 2025 is on the bottom and the power cable 2023 is on the top, but the signal cable 2025 may be on the top and the power cable 2023 on the bottom.

[0193] 25 shows the inside of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device as seen from the side. The sensor cable 2024 can be arranged, for example, so as to pass between the lower part inside the housing 1190 and the display device 1.

[0194] In the above, an example has been described in which the circuit unit 2002 is arranged on the left side of the floating image display unit 2001 as seen from the user 230, but conversely, a space-floating image display device may be provided in which the circuit unit 2002 is arranged on the right side of the floating image display unit 2001 as seen from the user 230. In response to the left-right reversal of the arrangement of the circuit unit 2002 and the floating image display unit 2001, the position of the aerial operation detection sensor 1351 and the arrangement of the cables may also be changed so that they are left-right reversed.

[0195] Next, an example of another structure will be described with reference to FIG. 26. The same description as above may be omitted. While the above-described space-floating image display device 2000A has a structure in which the space housing floating image display unit 2001 and the space housing circuit unit 2002 are connected in the left-right direction within housing 1190, space-floating image display device 2000B of this example has a structure in which the space housing floating image display unit 2001 and the space housing circuit unit 2002 are connected in the up-down direction, i.e., in the z-axis direction, within housing 1190. In this structure, circuit unit 2002 is positioned offset in the up-down direction relative to floating image display unit 2001, and circuit unit 2002 is housed below floating image display unit 2001. This space-floating image display device 2000B has a structure that limits its length in the left-right direction, allowing it to be installed in a narrow space.

[0196] In this space floating image display device 2000B, the circuit unit 2002 is arranged so that it does not overlap the retroreflector 5 and the display device 1 in the front-to-back direction, i.e., in the y-axis direction, and is behind the retroreflector 5 and in front of the display device 1 in the front-to-back direction. In this structure, a space is created on the back side of the circuit unit 2002 to allow the exhaust heat of the light source to escape. Also, there is a space on the back side of the display device 1 (more specifically, the light source), and this space reduces the accumulation of the exhaust heat of the light source. A boss 2031 may be provided on the back side of the display device 1, between the display device 1 and the housing 1190.

[0197] 27 shows the inside of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device as viewed from the front side. In this space-floating image display device 2000B, boards such as a power supply board 2021 and a signal board 2022 are arranged below the floating image display unit 2001 (i.e., the light source, display panel, and retroreflector 5). Therefore, there are no components on the front of the boards, making it possible to perform work from the front side. For example, it becomes possible to tighten screws from the front side and remove boards from the front side.

[0198] Furthermore, with respect to the power supply substrate 2021 and the signal substrate 2022, the power supply substrate 2021, which generates a larger amount of heat, may be disposed below the signal substrate 2022. That is, it is preferable that the distance between the position of the power supply substrate 2021 and the display device 1 (more specifically, the light source) is longer than the distance between the position of the signal substrate 2022 and the display device 1 (more specifically, the light source). By separating the power supply substrate 2021, which generates a larger amount of heat, from the light source, it is possible to reduce the accumulation of exhaust heat. Furthermore, by separating the power supply substrate 2021, which generates a larger amount of heat, from the liquid crystal display panel 11, it is possible to suppress a rise in temperature of the liquid crystal display panel 11.

[0199] The signal cable 2025 and sensor cable 2024 connected to the signal board 2022, and the power cable 2023 connected to the power board 2021 can be positioned as appropriate. The positions of the terminals of the signal board 2022 and the power board 2021 can be set as appropriate. The space floating image display device 2000B may be provided with a cover that can cover each terminal provided on the board and the cable connected to each terminal.

[0200] Next, an example of another structure will be described with reference to Fig. 28. Descriptions similar to those above may be omitted. While the above-described space-floating image display device 2000B has a structure in which the circuit unit 2002 is housed below the floating image display unit 2001, the space-floating image display device 2000C of this example has a structure in which the circuit unit 2002 is housed above the floating image display unit 2001. Therefore, in this structure, the circuit unit 2002 is disposed offset in the vertical direction, i.e., in the z-axis direction, relative to the floating image display unit 2001. As with the above, this space-floating image display device 2000C has a structure in which the length in the horizontal direction is kept short, and can be installed in a narrow space.

[0201] In this space floating image display device 2000C, the circuit unit 2002 is arranged so that it does not overlap the retroreflector 5 and the display device 1 in the front-to-back direction, i.e., in the y-axis direction, and is behind the retroreflector 5 and in front of the display device 1 in the front-to-back direction. In this structure, a space is created above the light source to allow the exhaust heat of the light source to escape. Also, there is a space on the back side of the display device 1 (more specifically, the light source), which reduces the accumulation of exhaust heat from the light source. Note that a boss 2031 may be provided on the back side of the display device 1, between the display device 1 and the housing 1190.

[0202] 29 shows the inside of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device as viewed from the front side. In this space-floating image display device 2000C, boards such as a power supply board 2021 and a signal board 2022 are arranged above the floating image display unit 2001 (i.e., the light source, display panel, and retroreflector 5). Therefore, there are no components on the front of the boards, making it possible to perform work from the front side. For example, it becomes possible to tighten screws from the front side and remove boards from the front side.

[0203] Furthermore, with respect to the power supply substrate 2021 and the signal substrate 2022, the power supply substrate 2021, which generates a larger amount of heat, may be disposed above the signal substrate 2022. That is, it is preferable that the distance between the position of the power supply substrate 2021 and the display device 1 (more specifically, the light source) is longer than the distance between the position of the signal substrate 2022 and the display device 1 (more specifically, the light source). By separating the power supply substrate 2021, which generates a larger amount of heat, from the light source, it is possible to reduce the accumulation of exhaust heat. Furthermore, by separating the power supply substrate 2021, which generates a larger amount of heat, from the liquid crystal display panel 11, it is possible to suppress a rise in temperature of the liquid crystal display panel 11.

[0204] The signal cable 2025 and sensor cable 2024 connected to the signal board 2022, and the power cable 2023 connected to the power board 2021 can be positioned as appropriate. The positions of the terminals of the signal board 2022 and the power board 2021 can be set as appropriate. The space floating image display device 2000C may be provided with a cover that can cover each terminal provided on the board and the cable connected to each terminal.

[0205] 30, in the structure of space-floating image display device 2000C, power supply board 2021 and signal board 2022 may be arranged side by side in the left-right direction, i.e., the x-axis direction. Power supply board 2021 and signal board 2022 may also be arranged left-right reversely. Similarly, in the structure of above-mentioned space-floating image display device 2000B, power supply board 2021 and signal board 2022 may be arranged side by side in the left-right direction. Furthermore, in above-mentioned space-floating image display device 2000A, power supply board 2021 and signal board 2022 may be arranged side by side in the up-down direction.

[0206] Fig. 31 shows the inside of an example of a space-floating image display device, and is a cross-sectional view of the space-floating image display device viewed from the side. As shown in Fig. 31, in the space-floating image display device, the circuit unit 2002 is placed in front of the light source, not directly above the light source, so that the exhaust heat of the light source can be easily released. In addition, the board is less susceptible to the effect of the exhaust heat of the light source.

[0207] The technology according to this embodiment displays high-resolution, high-brightness video information in a state where it floats in space, allowing users to operate the device without worrying about contact infection. Applying the technology according to this embodiment to a system used by an unspecified number of users reduces the risk of contact infection and makes it possible to provide a contactless user interface that can be used without anxiety. This contributes to the "Good Health and Well-Being" goal, one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0208] Furthermore, the technology of this embodiment reduces the divergence angle of the emitted image light and aligns it with a specific polarization, thereby efficiently reflecting only the normal reflected light from the retroreflector, thereby enabling high light utilization efficiency and producing bright and clear floating images in space.The technology of this embodiment can provide a highly usable non-contact user interface that can significantly reduce power consumption.This contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote technological innovation and infrastructure" and "Make cities and human settlements sustainable."

[0209] Although various embodiments have been described above in detail, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system to clearly explain the present invention, and the present invention is not necessarily limited to a system including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0210] 1...display device, 2...retroreflector (retroreflector), 3...spatial image (space-floating image), 105...window glass, 100...transparent member, 101...polarized light separation member, 101B...polarized light separation member, 12...absorptive polarizer, 13...light source device, 54...light direction conversion panel, 151...retroreflector, 102, 202...LED substrate, 203...light guide, 205, 271...reflective sheet, 206, 270...phase difference plate, 230...user, 335...image light control sheet, 336...light transmitting section, 337...light shielding section, 1000, 1000A...space-floating image display device, 1110...control section, 1160...image control section, 1180...imaging section, 1102...image display display unit, 1350...air operation detection unit, 1351...air operation detection sensor, 1500 (1501 to 1503)...linear prism sheet (light beam direction change sheet), 1504...convex portion, 1505...concave portion (groove), 1506...uneven portion, 1507...first surface, 1508...second surface, 2000A, 2000B, 2000C...space floating image display device, 2001...floating image display unit, 2002...circuit unit, 2003...opening, 2011...fixing plate, 2021...power supply board, 2022...signal board, 2023...power cable, 2024...sensor cable, 2025...signal cable, 2026...terminal, 2031...boss, 2032...cover.

Claims

1. a display device for displaying an image; A retroreflector that reflects image light from the display device and displays a floating image in the air using the reflected light; a circuit unit on which the substrate is mounted, the circuit unit is arranged so as not to overlap the retroreflector and the display device, The retroreflector is disposed on the floating image side of the circuit unit, and the display device is disposed on the opposite side of the circuit unit from the floating image.

2. 2. The airborne image display device according to claim 1, The circuit unit is arranged at a position offset in either the left or right direction or the up or down direction relative to the retroreflector and the display device.

3. 2. The airborne image display device according to claim 1, The circuit unit includes a power supply board and a signal board for performing signal processing.

4. The airborne image display device according to claim 3, A floating-in-the-air image display device, wherein the distance between the position of the power supply substrate and the display device is longer than the distance between the position of the signal substrate and the display device.

5. 2. The airborne image display device according to claim 1, A floating image display device in which there is a space behind the display device.

6. 6. The airborne image display device according to claim 5, A floating image display device, in which a cable connecting the circuit unit and a sensor that detects user operations on the floating image displayed by the retroreflector is arranged in the space on the back side of the display device.

7. 6. The airborne image display device according to claim 5, A floating-in-the-air image display device, wherein a boss is provided on the rear side of the display device.

8. 7. The airborne image display device according to claim 6, The floating image display device has a boss provided on the rear side of the display device.

9. 2. The airborne image display device according to claim 1, A terminal for connecting a cable is provided on the front side of the substrate, the floating image display device.

10. The airborne image display device according to claim 9, The terminal is configured to allow a cable to be connected from a direction other than the front, in this floating image display device.

Images