Airborne suspended image display device

Abstract

The present application provides a better air suspension image display device. According to the present application, the contribution can be made to the sustainable development goals (SDGs) "3 good health and well-being", "9 industry, innovation and infrastructure", "11 sustainable cities and communities". The air suspension image display device (1000A) comprises: a display panel (11) which displays an image; a retroreflective sheeting (5) which reflects the image light from the display panel, and displays an aerial suspension image (3) of a real image in the air by using the reflected light; and a light beam travel direction changing sheet (1500) which is arranged between the display panel and the retroreflective sheeting, changes the travel direction of the image light from the display panel, wherein the light beam travel direction changing sheet is arranged close to the display panel.

Description

Technical Field

[0001] This invention relates to an aerial levitation image display device. Background Technology

[0002] Regarding the technology of displaying information suspended in the air, for example, it is disclosed in Patent Document 1.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-128722 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, the content disclosed in Patent Document 1 does not fully consider how to obtain practical brightness and quality of aerial levitation images, or how to make users enjoy watching aerial levitation images more pleasantly.

[0008] The purpose of this invention is to provide a better aerial levitation image display device.

[0009] Technical means to solve the problem

[0010] To address the aforementioned problems, for example, the structure described in the claimed technical solution can be employed. This application includes multiple technical solutions to solve the above problems, one example being the following: an aerial levitation image display device, comprising: a display panel displaying an image; a retroreflector reflecting image light from the display panel, thereby displaying an aerial levitation image of a real image in the air using the reflected light; and a beam travel direction changing plate disposed between the display panel and the retroreflector to change the travel direction of image light from the display panel, wherein the beam travel direction changing plate is disposed close to the display panel.

[0011] Invention Effects

[0012] The present invention enables the realization of a better aerial levitation image display device. Other technical problems, technical features, and technical effects will become clear in the following description of the embodiments. Attached Figure Description

[0013] Figure 1 This figure shows an example of the usage mode of a spatial levitation image display device according to an embodiment of the present invention.

[0014] Figure 2A This is a diagram illustrating an example of the main structure and retroreflective part structure of an aerial levitation image display device according to an embodiment of the present invention.

[0015] Figure 2B This is a projection diagram of the retroreflector that constitutes the aerial suspended image display device in one embodiment of the present invention.

[0016] Figure 2C This is a top view of the retroreflector that constitutes the aerial suspended image display device in one embodiment of the present invention.

[0017] Figure 2D This is a perspective view showing the corner reflector included in the retroreflector panel constituting the aerial suspended image display device in one embodiment of the present invention.

[0018] Figure 2E This is a top view showing the corner reflector included in the retroreflector that constitutes the aerial levitation image display device in one embodiment of the present invention.

[0019] Figure 2F This is a side view showing the corner reflector included in the retroreflector that constitutes the aerial levitation image display device in one embodiment of the present invention.

[0020] Figure 3 This is a diagram illustrating a structural example of a spatial levitation image display device according to an embodiment of the present invention.

[0021] Figure 4A This is a diagram illustrating an example of the structure of a spatial levitation image display device according to an embodiment of the present invention.

[0022] Figure 4B This is a diagram illustrating an example of the structure of a spatial levitation image display device according to an embodiment of the present invention.

[0023] Figure 4C This is a diagram illustrating an example of the structure of a spatial levitation image display device according to an embodiment of the present invention.

[0024] Figure 5 This is a cross-sectional view illustrating an example of the specific structure of a light source device according to an embodiment of the present invention.

[0025] Figure 6 This is a cross-sectional view illustrating an example of the specific structure of a light source device according to an embodiment of the present invention.

[0026] Figure 7 This is a cross-sectional view illustrating an example of the specific structure of a light source device according to an embodiment of the present invention.

[0027] Figure 8 This is a configuration diagram showing the main parts of a spatial levitation image display device according to an embodiment of the present invention.

[0028] Figure 9 This is a cross-sectional view showing the structure of a display device according to an embodiment of the present invention.

[0029] Figure 10 This is a cross-sectional view showing the structure of a display device according to an embodiment of the present invention.

[0030] Figure 11 This is an explanatory diagram illustrating the light source diffusion characteristics of an image display device according to an embodiment of the present invention.

[0031] Figure 12 This is an explanatory diagram illustrating the diffusion characteristics of an image display device according to an embodiment of the present invention.

[0032] Figure 13A This is a diagram illustrating an example of the main structure and retroreflective part structure of an aerial levitation image display device according to an embodiment of the present invention.

[0033] Figure 13B This is a diagram illustrating an example of the main structure and retroreflective part structure of an aerial levitation image display device according to an embodiment of the present invention.

[0034] Figure 14A This is a diagram illustrating an example of the main structure and retroreflective part structure of an aerial levitation image display device according to an embodiment of the present invention.

[0035] Figure 14B This is a diagram illustrating an example of the main structure and retroreflective part structure of an aerial levitation image display device according to an embodiment of the present invention.

[0036] Figure 15 This is an enlarged view illustrating the main structural components of an aerial levitation image display device according to an embodiment of the present invention.

[0037] Figure 16 This is an enlarged view illustrating the main structural components of an aerial levitation image display device according to an embodiment of the present invention.

[0038] Figure 17 This is a diagram illustrating an example of the structure of an image light control sheet according to an embodiment of the present invention.

[0039] Figure 18 This is an enlarged view illustrating the main structural components of a spatial levitation image display device according to an embodiment of the present invention.

[0040] Figure 19 This is a diagram illustrating an example of various settings in a spatial levitation image display device according to an embodiment of the present invention. Detailed Implementation

[0041] The embodiments of the present invention are described in detail below based on the accompanying drawings. However, the present invention is not limited to the description of the embodiments, and those skilled in the art can make various changes and modifications within the scope of the technical concept disclosed in this specification. Furthermore, in all the drawings used to illustrate the present invention, parts having the same function are labeled with the same reference numerals, and sometimes repeated descriptions are omitted.

[0042] The following embodiments relate to an image display device that enables an image formed by image light from an image light source to be transmitted through a transparent component such as glass used to separate space, and displayed outside the transparent component as a spatially suspended image. Furthermore, in the following description of the embodiments, the term "spatially suspended image" is used to describe an image suspended in space. Alternatively, it can be expressed as "aerial image," "spatial image," "aerially suspended image," "spatially suspended optical image displaying an image," "aerially suspended optical image displaying an image," etc. The term "spatially suspended image" primarily used in the description of the embodiments is taken as a representative example of these terms.

[0043] According to the following embodiments, a good image display device can be implemented in, for example, bank ATMs, station ticket machines, digital signage, etc. For example, while touch panels are commonly used in bank ATMs and station ticket machines, transparent glass or light-transmitting panels can also be used to display high-resolution image information in a spatially suspended state. In this case, by reducing the divergence angle of the emitted image light to an acute angle, and then unifying it to a specific polarization, only the light normally reflected by the retroreflector can be efficiently reflected. Therefore, light utilization efficiency is high, and ghosting, which is a problem in existing retroreflection methods besides the main spatially suspended image, can be suppressed, resulting in a clear spatially suspended image. Furthermore, by using a device including the light source of this embodiment, a novel and highly usable spatially suspended image display device (spatially suspended image display system) that significantly reduces power consumption can be provided. Additionally, for example, a vehicle-use spatially suspended image display device capable of displaying so-called one-way spatially suspended images can be provided, which can be viewed from inside and / or outside the vehicle.

[0044] <Example 1>

[0045] Hereinafter, as Embodiment 1 of the present invention, a structural example of a spatial levitation image display device will be described.

[0046] <An example of the usage of a spatial levitation image display device>

[0047] Figure 1Figure 2 shows an example of the usage mode of the spatial levitation image display device according to an embodiment of the present invention, and also shows the overall structure of the spatial levitation image display device of this embodiment. The specific structure of the spatial levitation image display device will be described in detail using Figure 2 and the like. In this device, light with narrow-angle pointing characteristics and specific polarization emitted from the image display device 1 is used as an image beam. After reflection by the optical system within the spatial levitation image display device, it first enters the retroreflector plate 2. After retroreflection, it passes through the transparent component 100 (glass, etc.) and forms a real aerial image (spatial levitation image 3) on the outer side of the glass surface. In addition, in the following embodiments, the retroreflector plate 2 (retroreflective reflector) is used as an example of a retroreflective component. However, the retroreflector plate 2 of the present invention is not limited to a planar plate. It is used as an example, and its concept includes a sheet-like retroreflective component that can be attached to a planar or non-planar component, and an entire assembly obtained by attaching a sheet-like retroreflective component to a planar or non-planar component. In addition, the light reflected by the retroreflector plate 2 has optical characteristics that enable imaging, so the retroreflector plate 2 can also be expressed as an imaging optical component or an imaging optical plate.

[0048] Furthermore, in shops and similar establishments, display windows (also known as "window glass") 105, constructed from translucent components such as glass, divide the space. The spatial levitation image display device according to this embodiment can display levitation images unidirectionally to the exterior and / or interior of the shop (space) through these transparent components.

[0049] Figure 1 In this context, the inner side of the window glass 105 (inside the shop) is considered as the depth direction, and its outer side (e.g., the sidewalk) as the near side. On the other hand, light can also be reflected by providing a mechanism on the window glass 105 that performs specific polarization reflection, thus forming an aerial image at a desired location inside the shop.

[0050] <Example of the structure of the optical system of a spatial levitation image display device>

[0051] use Figure 2A Explain the structure of the optical system of a spatial levitation image display device. Figure 2A The optical system uses a retroreflector 5. The following describes the optical system using... Figures 2A to 2F A more specific example of the structure of an optical system will be given.

[0052] Figure 2A This diagram illustrates an example of the main structure and retroreflective section structure of a spatial levitation image display device according to an embodiment of the present invention. A display device 1, which emits image light, is provided in the oblique direction of a transparent component 100 such as glass. The display device 1 includes a liquid crystal display panel 11 and a light source device 13 for generating light.

[0053] The main 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 can be, for example, 45°. However, the incident angle α is not limited to 45°, and for example, 45°±15° can be used.

[0054] The retroreflector 5 is an optical component that has the optical property of causing retroreflective reflection of light in at least a portion of its directions. Furthermore, the reflected light possesses optical properties capable of forming an image, so the retroreflector 5 can also be described as an imaging optical component or an imaging optical plate.

[0055] use Figure 2B , Figure 2C The specific structure of the retroreflector 5 will be described in detail later. Under the action of the retroreflector 5, the principal ray 9020 travels in the z direction while undergoing retroreflection in the x and y directions. As a result, the reflected ray 9021 travels away from the retroreflector 5 in a mirror-symmetric optical path relative to the principal ray 9020 with the retroreflector 5 as the reference, and passes through the transparent component 100 to form a spatially suspended image 3 as a real image on the imaging surface.

[0056] The light beam that forms the spatial levitation image 3 is a collection of light rays converged from the retroreflector 5 to the optical image of the spatial levitation image 3. These light rays continue to travel in a straight line after passing through the optical image of the spatial levitation image 3. Therefore, the spatial levitation image 3, unlike diffused images formed on a screen using a conventional projector, is a highly directional image. Thus, in the structure shown in Figure 2, when a user views from the direction of arrow A, the spatial levitation image 3 can be seen as a bright image. However, when other people view from the direction of arrow B, the spatial levitation image 3 cannot be seen at all. This characteristic is suitable for systems displaying images requiring high security, and systems displaying highly confidential images that need to be kept secret from people directly facing the user.

[0057] use Figure 2B , Figure 2C An example of the structure of the retroreflector 5 will be described. The retroreflector 5 is a structure in which multiple corner reflectors 9040 are arranged in an array on the surface of a transparent component. It can also be referred to as a corner reflector array or a multi-faceted reflector array. The specific structure of the corner reflectors 9040 will be explained using... Figure 2D , Figure 2E , Figure 2FIn detail, the light rays 9111, 9112, 9113, and 9114 emitted from the light source 9110 are reflected twice by the two mirrors 9041 and 9042 of the corner reflector 9040, becoming reflected light rays 9121, 9122, 9123, and 9124. These two reflections are retrograde reflections in the x and y directions, returning in the same direction as the incident direction (traveling in a direction rotated 180°). In the z direction, they are normal reflections (specular reflection) due to total internal reflection, where the angle of incidence and the angle of reflection are the same.

[0058] That is, rays 9111 to 9114 produce reflected rays 9121 to 9124 along a straight line symmetrical about the corner reflector 9040 in the z-direction, forming a real image 9120 in the air. Furthermore, rays 9111 to 9114 emanating from the light source 9110 represent four rays of diffused light from the light source 9110. Depending on the diffusion characteristics of the light source 9110, the rays incident on the retroreflector 5 are not limited to these, but all incident rays undergo the same reflection, forming a real image 9120 in the air. Additionally, for ease of viewing, the positions of the light source 9110 and the real image 9120 in the x-direction are shown offset, but in reality, the positions of the light source 9110 and the real image 9120 in the x-direction are the same, coinciding when viewed from the z-direction.

[0059] Next, using Figure 2D , Figure 2E , Figure 2F The structure and effect of the corner reflector 9040 constituting the retroreflector 5 will be explained. The corner reflector 9040 is a cuboid with only two specific surfaces being mirror surfaces 9041 and 9042, and the other four surfaces being transparent components. The retroreflector 5 is configured such that the corner reflectors 9040 are arranged in an array with the corresponding mirror surfaces facing the same direction.

[0060] When viewed from the top surface (+z direction), the light ray 9111 emitted from the light source 9110 is incident on the mirror 9041 (or mirror 9042) at a specific angle of incidence. After total internal reflection occurs at the reflection point 9130, total internal reflection occurs again at the reflection point 9132 on the mirror 9042 (or mirror 9041).

[0061] Let θ be the angle of incidence of ray 9111 on mirror 9041 (or mirror 9042). Then, the angle of incidence of the first reflected ray 9131, after reflection on mirror 9041 (or mirror 9042), relative to mirror 9042 (or mirror 9041), can be expressed as 90°-θ. Therefore, relative to ray 9111, the second reflected ray 9121 rotates by 2θ due to the first reflection and by 2×(90°-θ) due to the second reflection, resulting in a total reversal of 180°. On the other hand, when viewed from the side (the midway between -x and -y), total internal reflection in the z-direction occurs only once. Therefore, if φ is the angle of incidence on mirror 9041 or mirror 9042, then the reflected ray 9121 rotates by 2×φ relative to ray 9111 due to the first reflection.

[0062] As described above, the light incident on the corner reflector 9040 undergoes retrograde reflection in the x and y directions, resulting in a reversed light path, and in the z direction, it undergoes orthogonal reflection caused by total internal reflection. Considering the retrograde reflector 5, since all light paths undergo the same reflection, a point image is formed symmetrically in the z-axis direction due to the converging reversed light paths in the x and y directions.

[0063] Figure 2A In the optical system, the retroreflector 5 has retroreflective properties along two axes and orthographic reflection along the other axis. Thus, when a diffusing incident beam is incident on the retroreflector 5, the converging reflected beam, after being reflected by the corner reflector array, travels relative to the retroreflector 5 on the opposite side from the side where the incident light source is located. This converging reflected beam forms an image in the air, creating a spatially suspended image 3.

[0064] The direction of travel of the principal ray of the converging reflected beam after being reflected by the corner reflector array of the retroreflector 5 is not the opposite direction of travel of the principal ray of the diffusing incident beam incident on the retroreflector 5. The component of the normal direction of the principal ray of the diffusing incident beam incident on the retroreflector 5 and the component of the normal direction of the surface of the plate shape of the retroreflector 5 of the direction of travel of the principal ray after being reflected on the retroreflector 5 to become a converging reflected beam do not change before and after reflection by the corner reflector array, but travel in a straight line.

[0065] That is, through reflection on the retroreflector 5, the diffuse incident beam is transformed into a converging reflected beam, but in the direction normal to the surface of the retroreflector 5, the beam travels through the retroreflector 5. Here, the diffuse incident beam incident on the retroreflector 5 and the converging reflected beam exiting the retroreflector 5 have a geometrically symmetrical relationship with respect to the surface of the retroreflector 5.

[0066] Regarding the spatial levitation image obtained by imaging light from display device 1, its resolution depends not only on the resolution of liquid crystal display panel 11, but also significantly on... Figure 2B , Figure 2C The diameter D and spacing P of the retroreflective portion of the retroreflective plate 5 shown are not illustrated. For example, when using a 7-inch WUXGA (1920×1200 pixels) LCD panel, even if one pixel (one triplet) is approximately 80μm, if the diameter D of the retroreflective portion is 240μm and the spacing P is 300μm, then one pixel of the spatial levitation image is equivalent to 300μm. Therefore, the effective resolution of the spatial levitation image is reduced to about one-third.

[0067] Therefore, in order to make the resolution of the spatially suspended image the same as that of the display device 1, it is preferable to make the diameter D and the spacing P of the retroreflective portion close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress moiré patterns caused by the pixels of the retroreflective plate and the liquid crystal display panel, the spacing ratio of each can be designed to deviate from one pixel by an integer multiple. In addition, the shape can be configured such that neither side of the retroreflective portion coincides with either side of one pixel of the liquid crystal display panel.

[0068] Furthermore, the shape of the retroreflective plate (imaging optical plate) in this embodiment is not limited to the examples described above. It can have various shapes to achieve retroreflection. Specifically, it can be various cubic corner reflectors, corner reflector arrays, slit mirror arrays, dihedral corner reflector arrays, multifaceted reflector arrays, or combinations of these reflective surfaces arranged periodically. Alternatively, a capsule lens type retroreflective element obtained by periodically arranging glass microspheres on the surface of the retroreflective plate in this embodiment can also be used. Detailed structures of these retroreflective elements can be derived using existing technology, so detailed descriptions are omitted. Specifically, technologies disclosed in Japanese Patent Application Publication No. 2017-33005, Japanese Patent Application Publication No. 2019-133110, Japanese Patent Application Publication No. 2017-67933, and WO2009 / 131128 can be used.

[0069] in addition, Figure 2A In the optical system, the image light emitted from the display device 1 can be in any polarization state. Whether it is S-polarization or P-polarization is not a problem.

[0070] As explained above, Figure 2A The optical system can create better spatial levitation images.

[0071] Based on the above explanation Figure 2AIts optical system can provide brighter, higher-quality images of spatial levitation.

[0072] <<Block diagram of the internal structure of the spatial levitation image display device>>

[0073] Next, a block diagram of the internal structure of the spatial levitation image display device 1000 will be described. Figure 3 This is a block diagram illustrating an example of the internal structure of a spatial levitation image display device 1000.

[0074] The spatial levitation image display device 1000 includes a retroreflective unit 1101, an image display unit 1102, a light guide 1104, a light source 1105, a power supply 1106, an external power input interface 1111, an operation input unit 1107, a non-volatile memory 1108, a memory 1109, a control unit 1110, an image signal input unit 1131, an audio signal input unit 1133, a communication unit 1132, an air operation detection sensor 1351, an air operation detection unit 1350, an audio output unit 1140, a microphone 1139, an image control unit 1160, a storage unit 1170, and a camera unit 1180. Additionally, it may also include a movable media interface 1134, an attitude sensor 1113, a transmissive self-emissive image display device 1650, a second display device 1680, or a secondary battery 1112.

[0075] The various components of the spatial levitation image display device 1000 are arranged within the housing 1190. Furthermore, Figure 3 The camera unit 1180 and the air operation detection sensor 1351 shown can also be located on the outside of the housing 1190.

[0076] Figure 3 The return reflection section 1101 corresponds to Figure 2A The retroreflector 5. The retroreflector 1101 causes the light modulated by the image display unit 1102 to undergo retroreflection. The spatial levitation image 3 is formed by utilizing the light from the reflected light from the retroreflector 1101 that is output to the outside of the spatial levitation image display device 1000. Application Figure 2A In the case of an optical system, the retroreflector 1101 corresponds to Figure 2A 5. Regression reflector.

[0077] Figure 3 The image display unit 1102 corresponds to Figure 2A LCD display panel 11. Figure 3 The light source 1105 corresponds to Figure 2A The light source device 13. Figure 3 The image display unit 1102, light guide 1104, and light source 1105 correspond to Figure 2A Display device 1.

[0078] The image display unit 1102 is a display unit that generates an image by modulating transmitted light based on an image signal input under the control of the image control unit 1160 (described later). The image display unit 1102 (the aforementioned liquid crystal display panel 11) may use, for example, a transmissive liquid crystal panel, but is not limited thereto. Alternatively, the image display unit 1102 may use, for example, a reflective liquid crystal panel that modulates reflected light or a DMD (Digital Micromirror Device) panel.

[0079] 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 laser. The power supply 1106 converts AC current input from the outside via the external power input interface 1111 into DC current to power the light source 1105. Additionally, the power supply 1106 supplies necessary DC current to various components within the spatial levitation image display device 1000. The secondary battery 1112 stores the power supplied by the power supply 1106. Furthermore, when not powered externally via the external power input interface 1111, the secondary battery 1112 powers the light source 1105 and other structures requiring electricity. In other words, with the secondary battery 1112 in place, the spatial levitation image display device 1000 can be used by the user even without external power.

[0080] The light guide 1104 guides the light generated by the light source 1105, directing it towards the image display unit 1102. The combination of the light guide 1104 and the light source 1105 can also be referred to as the backlight of the image display unit 1102. The light guide 1104 can be constructed primarily of glass. Alternatively, it can be constructed primarily of plastic. It can also be constructed using a reflector. Various combinations of the light guide 1104 and the light source 1105 are possible. Specific structural examples of the combination of the light guide 1104 and the light source 1105 will be described in detail later.

[0081] The airborne operation detection sensor 1351 is a sensor that detects the operation of a user's finger or other object on the spatial levitation image 3. For example, the airborne operation detection sensor 1351 senses the area overlapping the entire display area of ​​the spatial levitation image 3. Alternatively, the airborne operation detection sensor 1351 may sense only the area overlapping at least a portion of the display area of ​​the spatial levitation image 3.

[0082] As a specific example of the airborne operation detection sensor 1351, a distance sensor using non-visible light such as infrared, non-visible light laser, or ultrasound can be cited. Alternatively, the airborne operation detection sensor 1351 can also combine multiple sensors to form a system capable of detecting coordinates in a two-dimensional plane. Furthermore, the airborne operation detection sensor 1351 can be constructed from a ToF (Time of Flight) type LiDAR (Light Detection and Ranging) sensor or an image sensor.

[0083] The airborne operation detection sensor 1351 only needs to be able to sense and detect touch operations performed by the user's finger on an object displayed as a spatial levitation image 3. Such sensing can be performed using existing technology.

[0084] The airborne operation detection unit 1350 acquires sensing signals from the airborne operation detection sensor 1351, determines whether the user's finger has made contact with an object in the spatial levitation image 3 based on the sensing signals, and calculates the position of contact between the user's finger and the object (contact position). The airborne operation detection unit 1350 is constructed, for example, by a circuit such as an FPGA (Field Programmable Gate Array). Additionally, some functions of the airborne operation detection unit 1350 can also be implemented in software, for example, through a spaceborne operation detection program executed by the control unit 1110 or the image control unit 1160. The airborne operation detection sensor 1351 and the airborne operation detection unit 1350 can also be integrated. The airborne operation detection unit 1350 and the control unit 1110 or the image control unit 1160 can also be integrated.

[0085] The airborne operation detection sensor 1351 and the airborne operation detection unit 1350 can be built into the space-based levitation image display device 1000, or they can be separately installed externally. When separately installed from the space-based levitation image display device 1000, the airborne operation detection sensor 1351 and the airborne operation detection unit 1350 are configured to transmit information and signals to the space-based levitation image display device 1000 via a wired or wireless communication connection path or an image signal transmission path. Therefore, a system can be constructed that optionally adds only airborne operation detection functionality, using the space-based levitation image display device 1000, which does not have airborne operation detection functionality, as the main body.

[0086] Alternatively, only the airborne operation detection sensor 1351 can be separated, and the airborne operation detection unit 1350 can be integrated into the space-based levitation image display device 1000. In cases where it is desirable to have more flexibility in the placement of the airborne operation detection sensor 1351 relative to the location of the space-based levitation image display device 1000, the structure that separates only the airborne operation detection sensor 1351 has advantages.

[0087] The camera unit 1180 is, for example, a camera with an image sensor, that captures images of the space near the levitation image 3 and / or the user 230's face, arms, fingers, etc. Multiple camera units 1180 can be provided. For example, a stereo camera can be used as the camera unit 1180. By using multiple camera units 1180, or by using a camera unit with a depth sensor, the air operation detection unit 1350 can be assisted when detecting touch operations by the user 230 on the levitation image 3. The camera unit 1180 can also be provided separately from the levitation image display device 1000. When the camera unit 1180 is provided separately from the levitation image display device 1000, it can be configured to transmit camera signals to the levitation image display device 1000 via a wired or wireless communication connection path.

[0088] For example, if the air operation detection sensor 1351 is configured to detect whether an object has invaded the intrusion detection plane by taking the display surface (display range) including the spatial levitation image 3 as the object, there may be situations where the air operation detection sensor 1351 cannot detect how far away an object (such as a user's finger) that has not invaded the intrusion detection plane is from the intrusion detection plane, or how close the object is to the intrusion detection plane.

[0089] In this case, by using depth calculation information of the object obtained from images captured by multiple camera units 1180 and depth information of the object obtained by a depth sensor, the distance between the object and the intrusion detection plane (spatial levitation image 3) can be calculated. Then, this depth calculation information, depth information, distance between the object and the intrusion detection plane, and other information are used for various display controls of the spatial levitation image 3.

[0090] Alternatively, instead of using the airborne operation detection sensor 1351, the airborne operation detection unit 1350 can detect the user 230's touch operation on the spatially suspended image 3 based on the images captured by the camera unit 1180. In this case, the camera unit 1180 can be referred to as the airborne operation detection sensor.

[0091] Alternatively, the camera unit 1180 can capture the face of the user operating the suspended image 3, and the control unit 1110 and other units can perform user recognition processing. In addition, in order to determine whether there are other people standing around or behind the user operating the suspended image 3, or whether others are spying on the user's operation of the suspended image 3, the camera unit 1180 can also capture images of the area including the user operating the suspended image 3 and the area surrounding the user.

[0092] The operation input unit 1107 is, for example, a signal receiving unit or an infrared receiving unit such as an operation button or a remote control, which inputs signals for operations different from those performed by the user in the air (touch operation). In addition to the user who performs touch operation on the spatial levitation image 3, the operation input unit 1107 can also be used by an administrator to operate the spatial levitation image display device 1000.

[0093] The image signal input unit 1131 connects to an external image output device to input image data (image signal). The image signal input unit 1131 can be various digital image input interfaces. For example, it can be configured with an HDMI (High-Definition Multimedia Interface) standard image input interface, a DVI (Digital Visual Interface) standard image input interface, or a DisplayPort standard image input interface. Alternatively, analog image input interfaces such as analog RGB and component video can also be provided.

[0094] The audio signal input unit 1133 connects to an external audio output device to input audio data (audio signal). The audio signal input unit 1133 can be configured as an HDMI standard audio input interface, an optical digital terminal interface, or a coaxial digital terminal interface, etc. When using an HDMI standard interface, the video signal input unit 1131 and the audio signal input unit 1133 can be configured as an interface consisting of a terminal and a cable integrated into one.

[0095] The audio output unit 1140 is capable of outputting audio based on the audio data input to the audio signal input unit 1133. The audio output unit 1140 may be configured as a speaker 1140. The audio output unit 1140 may include components for performing sound synthesis processing (speech synthesis processing), etc. Additionally, the audio output unit 1140 may also output built-in operation tones and error warning tones. Alternatively, the audio output unit 1140 may be configured to output digital signals to external devices in a manner similar to the Audio Return Channel function specified in the HDMI standard.

[0096] The sound input unit 1139 can be composed of a microphone 1139. The microphone 1139 is a microphone that collects sound from the vicinity of the spatial levitation image display device 1000 and converts it into a signal to generate a sound signal. It can be configured such that the microphone collects the voice of a user or other person (speech), and the generated sound signal is processed by a control unit 1110 or similar device for sound recognition (speech recognition processing), from which text information is obtained. The sound input unit 1139 may include a component for performing sound recognition processing (speech recognition processing). Furthermore, the sound output unit 1140 and the sound input unit 1139 can also be connected as external devices to the spatial levitation image display device 1000.

[0097] The non-volatile memory 1108 stores various data used in the spatial levitation image display device 1000. The data stored in the non-volatile memory 1108 includes, for example, various operational data for displaying the spatial levitation image 3, display icons, data on objects for user operation, and layout information. The main memory 1109 stores image data displayed as the spatial levitation image 3 and control data for the device.

[0098] The control unit 1110 includes a processor and is capable of controlling the operation of each connected component. In addition, the control unit 1110 can cooperate with the program stored in the memory 1109 to perform calculations based on information obtained from each component within the spatial levitation image display device 1000.

[0099] The communication unit 1132 communicates with external devices, external servers, etc., via a wired or wireless communication interface. When the communication unit 1132 has a wired communication interface, this interface can be configured as, for example, a LAN interface using an Ethernet standard. When the communication unit 1132 has a wireless communication interface, it can be configured as, for example, a Wi-Fi communication interface, a Bluetooth communication interface, or a 4G or 5G mobile communication interface. Through communication via the communication unit 1132, various data such as video data, image data, and audio data are sent and received.

[0100] Additionally, the removable media interface 1134 is an interface for connecting a removable recording medium (removable medium). The removable recording medium (removable medium) can be composed of semiconductor memory such as a solid-state drive (SSD), magnetic recording media such as a hard disk drive (HDD), or optical recording media such as an optical disc. The removable media interface 1134 can read various data and information, such as image data, audio data, etc., recorded on the removable recording medium. The image data and audio data recorded on the removable recording medium are output as a spatial levitation image 3 via the image display unit 1102 and the retroreflective unit 1101.

[0101] Storage unit 1170 is a storage device that records various types of data and information, such as image data, audio data, etc. Storage unit 1170 can be composed of a magnetic recording medium recording device such as a hard disk drive (HDD) or a semiconductor device memory such as a solid-state drive (SSD). In storage unit 1170, for example, various types of data and information, such as image data, audio data, etc., can be pre-recorded at the time of product shipment. Furthermore, storage unit 1170 can also record various types of data and information, such as image data, audio data, etc., obtained from external devices and external servers via communication unit 1132.

[0102] The image data and other data recorded in the storage unit 1170 are processed by the image control unit 1160 and output as a spatial levitation image 3 via the image display unit 1102 and the retroreflection unit 1101. Image data and other data of the display icons and objects for user operation displayed as the spatial levitation image 3 are also recorded in the storage unit 1170. Layout information of the display icons and objects displayed as the spatial levitation image 3, as well as various metadata information about the objects, are also recorded in the storage unit 1170.

[0103] The sound data recorded in the storage unit 1170 is output as sound from the sound output unit 1140, for example.

[0104] The image control unit 1160 performs various controls on the image signals input to the image display unit 1102. Based on the image signals (image data), the image control unit 1160 generates image signals (display data) for displaying images on the image display unit 1102 (e.g., the liquid crystal display panel 11 of the display device 1 described above), and supplies them to the image display unit 1102. The image control unit 1160 can also be called an image processing circuit, and can be constructed from hardware such as an ASIC, FPGA, or video processor. Furthermore, the image control unit 1160 can also be called an image processing unit or an image processing unit. For example, the image control unit 1160 performs image switching control, switching which image signal, such as the image signal stored in the memory 1109 or the image signal (image data) input to the image signal input unit 1131, is input to the image display unit 1102.

[0105] Alternatively, the control unit 1110 may perform the same processing as the image control unit 1160; in this case, the control unit 1110 may be referred to as an image processing unit, etc. At least one of the control unit 1110, the image control unit 1160, the air operation detection unit 1360, etc., may perform unique control processing; in this case, the control unit 1110, the image control unit 1160, the air operation detection unit 1360, etc., may be referred to as an image processing unit.

[0106] In addition, the image control unit 1160 can also be controlled to generate a superimposed image signal obtained by superimposing the image signal stored in the memory 1109 and the image signal input from the image signal input unit 1131, and input the superimposed image signal to the image display unit 1102, thereby forming a composite image as a spatial levitation image 3.

[0107] Additionally, the image control unit 1160 can also perform control, and perform image processing on the image signals input from the image signal input unit 1131 and the image signals stored in the memory 1109. Examples of image processing include scaling (enlarging, reducing, and distorting the image), brightness adjustment (changing brightness), contrast adjustment (changing the image's contrast curve), and Retinex processing (decomposing the image into light components and changing the weights of each component).

[0108] Furthermore, the image control unit 1160 can also perform special effects image processing on the image signal input to the image display unit 1102 to assist the user's air operation (touch operation). Special effects image processing, for example, is performed based on the detection results of the user's touch operation by the air operation detection unit 1350 and the image captured by the camera unit 1180. Additionally, the image control unit 1160 can also perform sound control processing when sound is simultaneously output from the sound output unit 1140 along with the spatial levitation image 3. A sound control unit for this sound control processing can also be provided outside the image control unit 1160.

[0109] The attitude sensor 1113 is a sensor composed of a gravity sensor, an acceleration sensor, or a combination thereof, capable of detecting the setting attitude of the spatial levitation image display device 1000. The control unit 1110 can control the operation of each connected component based on the attitude detection results of the attitude sensor 1113. For example, if the attitude is detected to be unsuitable for the user, control can be implemented to stop the display of the image on the image display unit 1102 and display an error message to the user. Alternatively, if the attitude sensor 1113 detects a change in the setting attitude of the spatial levitation image display device 1000, control can be implemented to rotate the display direction of the image displayed on the image display unit 1102.

[0110] As explained above, the spatial levitation image display device 1000 is equipped with various functions. However, the spatial levitation image display device 1000 does not need to have all of these functions; it can have any structure as long as it has the function of forming the spatial levitation image 3.

[0111] <Structural Example of a Spatial Suspended Image Display Device>

[0112] Next, a structural example of the spatial levitation image display device will be described. Regarding the layout of the constituent elements of the spatial levitation image display device in this embodiment, various layouts may exist depending on the usage configuration. Hereinafter, [details to be added] Figures 4A to 4C The layout of each item will be explained. Additionally, in Figures 4A to 4C In any of these examples, the thick lines surrounding the constituent elements (display device 1, etc.) of the spatial levitation image display device 1000 represent the housing structure of the spatial levitation image display device 1000. Figure 3 An example of the housing 1190 in the example.

[0113] Figure 4A This is a diagram illustrating an example of the structure of a spatially suspended image display device. Figure 4A The space-floating image display device 1000 adopts Figure 2A A spatial levitation image display device with an optical system. Figure 4A In the spatial levitation image display device 1000, image light passing through the transparent component 100 is imaged in the air to form a spatial levitation image 3. Furthermore, the user's finger 9004's operation on the spatial levitation image 3 can be detected using sensing light from the user's perspective by using an air operation detection sensor 1351 located at the depth side of the transparent component 100. Additionally, the x-direction is the left-right direction from the user's perspective, the y-direction is the front-back direction (depth direction) from the user's perspective, and the z-direction is the up-down direction (vertical direction). Figure 4A The definitions of the x, y, and z directions are the same in subsequent diagrams, so repeated explanations will be omitted.

[0114] After adopting Figure 2A In the example of the space levitation image display device of the optical system, the space levitation image 3 is imaged in front of the transparent component 100 (on the side closer to the user), and the user's finger operation on the space levitation image 3 can be detected by the sensing light of the air operation detection sensor 1351, which is arranged deep on the transparent component 100 from the user's perspective.

[0115] then, Figure 4B This is a diagram illustrating an example of the structure of a spatially suspended image display device. Figure 4B Is Figure 4A The diagram shows the structure of the internal optical system in the spatial levitation image display device 1000. Figure 4B The space-floating image display device 1000 shown is equipped with... Figure 2A The optical system corresponding to the optical system. Figure 4B The spatial levitation image display device 1000 shown is horizontally arranged with the side forming the spatial levitation image 3 facing upwards.

[0116] Right now, Figure 4BIn this device, the transparent component 100 of the spatial levitation image display device 1000 is disposed on the top surface of the device. The spatial levitation image 3 is formed above the surface of the transparent component 100 of the spatial levitation image display device 1000. The light from the spatial levitation image 3 travels obliquely upward. When the air operation detection sensor 1351 is disposed as shown in the figure, it is possible to detect the operation of the user 230's finger on the spatial levitation image 3.

[0117] in addition, Figure 4B In the middle, the display device 1 and the spatial levitation image 3 are symmetrical about each other with the surface of the retroreflector 5 as the reference.

[0118] Figure 4C This is a diagram illustrating an example of the structure of a spatially suspended image display device. Figure 4C The space-floating image display device 1000 shown is equipped with... Figure 2A The optical system corresponding to the optical system. Figure 4C The spatial levitation image display device 1000 shown is vertically arranged such that the side forming the spatial levitation image 3 faces the front of the spatial levitation image display device 1000 (the direction of the user 230). That is, Figure 4C In the spatial levitation image display device 1000, the transparent component 100 is disposed on the front of the device (to the user 230). The spatial levitation image 3 is formed on the user 230 side, relative to the surface of the transparent component 100. The light from the spatial levitation image 3 travels obliquely upwards. Figure 4C With the airborne operation detection sensor 1351 set up as shown, it is possible to detect the user 230's finger operation on the spatially suspended image 3. Here, as... Figure 4C As shown, the airborne operation detection sensor 1351 senses the user 230's finger from above and uses the reflection of sensing light from the user 230's fingernail for touch detection. Generally, fingernails have a higher reflectivity than fingertips, so by adopting such a structure, the accuracy of touch detection can be improved.

[0119] according to Figures 4A to 4C The structure of the spatial levitation image display device enables the use of Figure 2A The optical system enables an easy-to-use spatial levitation image display device.

[0120] <Display Device>

[0121] Next, the display device 1 of this embodiment will be described using the accompanying drawings. The display device 1 of this embodiment includes an image display element 11, i.e., a liquid crystal display panel 11, and a light source device 13 constituting the light source of the liquid crystal display panel 11. Figure 5In the figure, the light source device 13 is shown in an unfolded perspective view along with the liquid crystal display panel.

[0122] The liquid crystal display panel 11, i.e., the image display element 11, is as follows: Figure 5 As indicated by arrow 30, an illumination beam with laser-like characteristics—a strong directional beam (in other words, linear travel) and a uniform polarization plane—is received from the light source device 13, which serves as a backlight. The liquid crystal display panel 11, i.e., the image display element 11, modulates the received illumination beam according to the input image signal. The modulated image light is reflected by the retroreflector 2 and passes through the transparent component 100 to form a spatially suspended image of a real image (see reference). Figure 1 ).

[0123] in addition, Figure 5 In this configuration, the display device 1 is equipped with a light source device 13, a liquid crystal display panel 11, and a light direction conversion panel 54 that controls the pointing characteristics of the emitted light beam from the light source device 13. It may also include a narrow-angle diffuser (not shown) as needed. Specifically, polarizers are provided on both sides of the liquid crystal display panel 11, such as... Figure 5 As indicated by arrow 30, the intensity of the light is modulated according to the image signal, resulting in the emission of image light with a specific polarization. Thus, the desired image, as highly directional (straight-line travel) specifically polarized light, is projected onto the retroreflector 2 via the light direction conversion panel 54. After reflection on the retroreflector 2, it is transmitted and travels towards... Figure 1 The viewer's eye outside the shop (space) forms a spatial levitation image 3. Alternatively, a protective cover 50 can be provided on the surface of the aforementioned light direction changing panel 54 (see reference). Figure 6 , Figure 7 ).

[0124] <Example 1 of a display device>

[0125] Figure 6 An example illustrating the specific structure of display device 1. Figure 6 exist Figure 5 The light source device 13 is equipped with a liquid crystal display panel 11 and a light direction conversion panel 54. This light source device 13 is constructed by housing LED elements 201 and a light guide 203 inside, for example, a plastic housing. On the end face of the light guide 203, in order to... Figure 5The lens shape shown converts the divergent light from each LED element 201 into a substantially parallel beam. It has a cross-sectional area that gradually increases towards the surface opposite the light-receiving part, and it allows for multiple total internal reflections during internal propagation, thereby gradually reducing the divergence angle. A liquid crystal display panel 11 constituting the display device 1 is mounted on the upper surface of the display device 1. Furthermore, an LED substrate 202 is mounted on one side of the light source device 13 (in this example, the left end face), on which the LED elements 201, serving as semiconductor light sources, and their control circuitry are mounted. A heat sink, i.e., a component for cooling the heat generated in the LED elements 201 and the control circuitry, can be mounted on the outer surface of the LED substrate 202.

[0126] Furthermore, on the frame (not shown) of the liquid crystal display panel 11 mounted on the upper surface of the housing of the light source device 13, the liquid crystal display panel 11 mounted on the frame, and the FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11 are mounted. That is, the image display element 11, i.e., the liquid crystal display panel 11, and the LED element 201, which serves as a solid-state light source, are based on the control circuit constituting the electronic device (…). Figure 3 The image control unit 1160 modulates the intensity of the transmitted light using a control signal to generate a display image. At this time, the generated image light has a narrow diffusion angle and only a specific polarization component, thus approximating a surface-emitting laser image source driven by an image signal, resulting in a novel image display device unlike any previously known. Furthermore, currently, obtaining a laser beam of the same size as the image obtained by the aforementioned display device 1 using a laser device is technically and safety-wise impossible. Therefore, in this embodiment, for example, a beam emitted by a conventional light source having LED elements is used to obtain light that approximates the surface-emitting laser image light.

[0127] Next, the structure of the optical system housed within the housing of the light source device 13 will be described with reference to... Figure 6 as well as Figure 7 Please explain in detail. Because... Figure 6 and Figure 7 This is a cross-sectional view, so only one of the multiple LED elements 201 constituting the light source is shown. They are transformed into approximately parallel light (collimated light) by the shape of the light-receiving end face 203a of the light guide 203. Therefore, the light-receiving part of the light guide end face is mounted in a predetermined positional relationship with the LED element 201.

[0128] Furthermore, the light guide 203 is formed, for example, using a light-transmitting resin such as acrylic resin. The LED light-receiving surface at the end of the light guide 203 has, for example, an outer peripheral surface in the shape of a convex cone obtained by rotating a parabolic section. Its top has a concave portion, and a convex portion (i.e., a convex lens surface) is formed in the center of this concave portion. Furthermore, the light-receiving portion of the light guide on which the LED element 201 is mounted has a parabolic shape forming a conical outer peripheral surface, and is set within an angle range that allows light emitted from the LED element in the peripheral direction to be totally internally reflected, or a reflective surface is formed.

[0129] On the other hand, LED elements 201 are respectively disposed at predetermined positions on the surface of its circuit board, i.e., LED substrate 202. The LED substrate 202 is disposed and fixed relative to the LED collimator, i.e., the light-receiving end face 203a, such that the LED elements 201 on its surface are respectively located at the center of the aforementioned recess.

[0130] According to this structure, the shape of the light-receiving end face 203a of the light guide 203 can be used to make the light emitted from the LED element 201 become approximately parallel light and output, thereby improving the utilization efficiency of the generated light.

[0131] As described above, the light source device 13 is configured by mounting a light source unit consisting of a plurality of LED elements 201 arranged as light sources at the light-receiving end face 203a, which is provided on the end face of the light guide 203. For the diverging light beam from the LED elements 201, the light-receiving end face 203a of the light guide 203 is made into approximately parallel light by the lens shape of the light-receiving end face 203a, and the light is guided inside the light guide 203 as shown by the arrow. The beam direction conversion unit 204 is used to direct the light beam to 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 beam direction conversion unit 204 by the shape of the interior or surface of the light guide 203, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled.

[0132] The aforementioned beam direction conversion unit 204 utilizes the surface shape of the light guide 203 or provides portions with different refractive indices within the light guide 203 to direct the beam propagating within the light guide 203 towards the liquid crystal display panel 11, which is arranged approximately parallel to the light guide 203. At this time, for the liquid crystal display panel 11, with the viewpoint positioned directly opposite the center of the screen and the diagonal dimension of the screen aligned with the center, the brightness of the center and periphery of the screen is compared. A relative brightness ratio of 20% or higher is sufficient for practical use, and a ratio exceeding 30% indicates even better performance.

[0133] in addition, Figure 6This is a cross-sectional view illustrating the structure and function of the light source in the light source device 13, which includes the light guide 203 and the LED element 201, according to this embodiment. Figure 6 In this light source device 13, for example, a light guide 203 made of plastic or the like with a beam direction conversion unit 204 disposed on its surface or inside, an LED element 201 serving as a light source, a reflector 205, a phase difference plate 206, a cylindrical lens, etc., are included. On the upper surface of the light source device 13, a liquid crystal display panel 11 with polarizers on the light source incident surface and the image light exit surface is mounted.

[0134] Furthermore, a thin film or sheet-like reflective polarizer 49 is provided on the light incident surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, so that one polarization (e.g., P-light) 212 of the natural light beam 210 emitted from the LED element 201 is selectively reflected. The reflected light is reflected again on a reflective sheet 205 provided on one surface (lower surface in the figure) of the light guide 203 and then returns to the liquid crystal display panel 11. For this purpose, a phase retardation plate (λ / 4 waveplate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizer 49. The reflected light (reflected beam) is reflected on the reflective sheet 205 and passes through the phase retardation plate (λ / 4 waveplate) a total of twice, thereby changing from P-polarization to S-polarization. This improves the utilization efficiency of the light source light as image light. The image beam with light intensity modulated by the liquid crystal display panel 11 according to the image signal is as follows: Figure 6 As indicated by arrow 213, the light exits and enters the retroreflector 2. After reflection on the retroreflector 2, a spatially suspended image of a real image is obtained.

[0135] Figure 7 Is with Figure 6 Similarly, a cross-sectional view is used to illustrate the structure and function of the light source in this embodiment, which performs polarization transformation in the light source device 13 including the light guide 203 and the LED element 201. The light source device 13 also includes, for example, a light guide 203 made of plastic or the like with a beam direction transformation unit 204 provided on its surface or internally, an LED element 201 serving as the light source, a reflector 205, a phase retardation plate 206, a cylindrical lens, etc. A liquid crystal display panel 11 with polarizers on the incident surface of the light source and the exit surface of the image light is mounted on the upper surface of the light source device 13.

[0136] A thin film or sheet-like reflective polarizer 49 is provided on the light incident surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, so that a certain polarization (e.g., S-ray) 211 in the natural light beam 210 emitted from the LED element 201 is selectively reflected. That is, Figure 7 In the example, the selective reflection characteristics of the reflective polarizer 49 are similar to... Figure 7The reflected light is reflected by a reflective sheet 205 located on one surface of the light guide 203 (lower in the figure) and then travels back to the liquid crystal display panel 11. A phase retardation plate (λ / 4 waveplate) is provided between the reflective sheet 205 and the light guide 203, or between the light guide 203 and the reflective polarizer 49. The reflected light (reflected beam) is reflected by the reflective sheet 205, thus passing through the phase retardation plate (λ / 4 waveplate) twice, thereby changing from S-polarization to P-polarization. This improves the utilization efficiency of the light source as image light. The image beam, whose light intensity is modulated by the liquid crystal display panel 11 according to the image signal, is as follows... Figure 7 As indicated by arrow 214, the light exits and enters the retroreflector 2. After reflection on the retroreflector 2, a spatially suspended image of a real image is obtained.

[0137] exist Figure 6 and Figure 7 In the light source device 13 shown, 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 is also used to reflect a polarization component. Therefore, theoretically, the contrast ratio that can be obtained is the product of the reciprocal of the orthogonal transmittance of the reflective polarizer and the reciprocal of the orthogonal transmittance obtained from the two polarizers attached to the liquid crystal display panel 11. As a result, a high contrast performance can be obtained. In fact, experiments have confirmed that the contrast performance of the displayed image is improved by more than 10 times. As a result, a high-quality image comparable to that of a self-emissive organic EL can be obtained.

[0138] <Example 2 of a display device>

[0139] Figure 8 Another example illustrating the specific structure of the display device 1 is shown below. The light source device 13 of this display device 1 is constructed, for example, by housing LEDs, collimators, synthetic diffusers, light guides, etc., within a plastic or similar enclosure. A liquid crystal display panel 11 is mounted on the upper surface of the light source device 13. Furthermore, an LED substrate 202 is mounted on one side of the enclosure of the light source device 13, on which LED elements 201, serving as semiconductor light sources, and control circuitry for the LED elements 201 are mounted. A heat sink 103, a component for cooling the heat generated in the LED elements 201 and the control circuitry, is mounted on the outer surface of the LED substrate 202.

[0140] Furthermore, on the liquid crystal display panel frame mounted on the upper surface of the housing of the light source device 13, a liquid crystal display panel 11 mounted on the frame and an FPC 403 electrically connected to the liquid crystal display panel 11 are provided. That is, the liquid crystal display panel 11, as a liquid crystal display element, and the LED element, as a solid-state light source, together modulate the intensity of the transmitted light based on the control signal from the control circuit (not shown) constituting the electronic device to generate a display image.

[0141] <Example 3 of a display device>

[0142] Next, use Figure 9 Another example illustrating the specific structure of display device 1 (Example 3 of the display device). The light source device of this display device 1 uses a collimator (LED collimator) 18 to convert the divergent beam of light (a mixture of P-polarized and S-polarized light) from LED 201 into a substantially parallel beam, and uses the reflective surface of the reflective light guide 304 to reflect it towards the liquid crystal display panel 11. 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 allows light of a specific polarization (e.g., P-polarized light) to pass through, causing the transmitted polarized light to enter the liquid crystal display panel 11. Here, other polarizations (e.g., S-polarized light) are reflected by the reflective polarizer 49 and return to the reflective light guide 304.

[0143] The reflective polarizer 49 is tilted relative to the liquid crystal display panel 11 in a manner that is not perpendicular to the principal ray of light from the reflective surface of the reflective light guide 304. The principal ray of light reflected from the reflective polarizer 49 is incident on the transmissive surface of the reflective light guide 304. The light incident on the transmissive surface of the reflective light guide 304 passes through the back of the reflective light guide 304, and after passing through the λ / 4 waveplate 270, which serves as a phase retardation plate, it is reflected on the reflective plate 271. The light reflected on the reflective plate 271 passes through the λ / 4 waveplate 270 again and through the transmissive surface of the reflective light guide 304. The light that has passed through the transmissive surface of the reflective light guide 304 is again incident on the reflective polarizer 49.

[0144] At this point, the light that is incident on the reflective polarizer 49 again passes through the λ / 4 waveplate 270 twice, so its polarization is transformed into a polarization that can pass through the reflective polarizer 49 (e.g., P-polarization). Thus, the polarization-transformed light passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Alternatively, the polarization design in the polarization transformation can be reversed compared to the above description (switching S-polarization and P-polarization).

[0145] As a result, the light from LED 201 is uniformly polarized (e.g., P-polarized) and incident on the liquid crystal display panel 11, and its brightness is modulated accordingly based on the image signal to display an image on the panel surface. Similar to the example above, multiple LEDs 201 constituting the light source are mounted in predetermined positions relative to their respective collimators 18. However, because... Figure 9 It is a longitudinal section view, so only one LED201 and one collimator 18 are shown.

[0146] Furthermore, the collimator 18 is formed, for example, using a light-transmitting resin such as acrylic resin or glass. The collimator 18 may have an outer peripheral surface with a convex conical shape obtained by rotating a parabolic section. Additionally, at the center of the top portion of the collimator 18 (the side opposite to the LED substrate 202), a recess with a protrusion (i.e., a convex lens surface) may be formed. Furthermore, at the center of the planar portion of the collimator 18 (the side opposite to the aforementioned top), a convex lens surface protruding outwards (or it may be a concave lens surface recessed inwards) may be formed. Additionally, the parabolic surface forming the conical outer peripheral surface of the collimator 18 is set within an angle range capable of causing total internal reflection of light emitted from the LED 201 in the peripheral direction, or a reflective surface is formed.

[0147] In addition, LEDs 201 are respectively disposed at predetermined positions on the surface of their circuit board, i.e., LED substrate 202. The LED substrate 202 is configured and fixed relative to the collimator 18 such that the LEDs 201 on its surface are respectively located at the central part of the top of the convex conical shape (or the recess if the top has a recess).

[0148] According to this structure, under the action of the collimator 18, the light emitted from the LED 201, especially the light emitted from its central portion, is converged into parallel light by the convex lens surface forming the shape of the collimator 18. Furthermore, light emitted from other portions towards the periphery is reflected by the parabolic surface of the conical outer peripheral surface of the collimator 18, and similarly converged into parallel light. In other words, by using the collimator 18, which has a convex lens in its central portion and a parabolic surface in its peripheral portion, almost all the light generated by the LED 201 can be output as parallel light, thereby improving the utilization efficiency of the generated light.

[0149] and then, Figure 9The light, transformed into approximately parallel light by collimator 18, is reflected by reflective light guide 304. A portion of this light, with a specific polarization, passes through reflective polarizer 49, and another portion, reflected by reflective polarizer 49, passes through light guide 304 again. This light is reflected by reflective plate 271, located opposite to the liquid crystal display panel 11 relative to reflective light guide 304. Here, the light undergoes polarization transformation twice by passing through λ / 4 waveplate 270, which acts as a phase difference plate. The light reflected by reflective plate 271 passes through light guide 304 again and is incident on reflective polarizer 49, which is positioned on the opposite side. Because the incident light has been polarized, it can pass through reflective polarizer 49, resulting in a uniform polarization direction incident on the liquid crystal display panel 11. As a result, all light from the light source can be utilized, achieving a 2-fold increase in geometrical optics efficiency. Furthermore, the polarization degree (extinction ratio) of the reflective polarizer 49 is also multiplied by the overall extinction ratio of the system, so the overall contrast of the display device is significantly improved by using the light source device of this embodiment. Additionally, by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflective plate 271, the reflection diffusion angle of light on each reflective surface can be adjusted. To improve the uniformity of light incident on the liquid crystal display panel 11, the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflective plate 271 can be adjusted according to each design.

[0150] in addition, Figure 9 For polarized light incident perpendicular to the λ / 4 waveplate 270, the phase difference does not need to be λ / 4. Figure 9 In this structure, any phase difference plate that allows polarized light to pass through twice, thus changing its phase by 90° (λ / 2), is sufficient. The thickness of the phase difference plate can be adjusted accordingly based on the incident angle distribution of the polarized light.

[0151] <Example 4 of a display device>

[0152] Furthermore, using Figure 10 Another example illustrating the structure of the optical system, such as the light source device, of the display device 1 (Example 4 of the display device). Example 4 of the display device is a structural example in which a diffuser is used instead of the reflective light guide 304 in the light source device of Example 3 of the display device. Specifically, on the light emitting side of the collimator 18, two optical sheets (in other words, diffusers) are used to transform the diffusion characteristics in the vertical and horizontal directions (front and back directions of the figure, not shown). The two optical sheets are represented by optical sheet 207A and optical sheet 207B. Light from the collimator 18 is incident between the two optical sheets.

[0153] Alternatively, the aforementioned optical sheet can be replaced with a single sheet instead of a two-sheet structure. With a single-sheet structure, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes of the front and back sides of the single optical sheet. Alternatively, multiple diffuser sheets can be used to share the effect. Here, in Figure 10 In the example, considering the reflection and diffusion characteristics determined by the front and back shapes of optical sheets 207A and 207B, the number of LEDs 201, the divergence angle emitted from the LED substrate 202, and the optical specifications of the collimator 18 can be used as design parameters for optimization, thereby making the surface density of the light beam emitted from the liquid crystal display panel 11 more uniform. That is, Figure 10 In the example, the surface shape of multiple diffusers is used instead of a light guide to adjust the diffusion characteristics.

[0154] Figure 10 In this example, the polarization transformation is performed using the same method as in Example 3 of the aforementioned display device. That is, in Figure 10 In this example, the reflective polarizer 49 can be configured to reflect S-polarized light (transmit P-polarized light). In this case, P-polarized light emitted from the light source, i.e., LED 201, is transmitted, and the transmitted light is incident on the liquid crystal display panel 11. S-polarized light emitted from the light source, i.e., LED 201, is reflected, and the reflected light passes through... Figure 10 The phase retardation plate 270 is shown. Light passing through the phase retardation plate 270 is reflected by the reflector plate 271. The light reflected by the reflector plate 271 passes through the phase retardation plate 270 again and is converted into P-polarized light. The polarized light passes through the reflective polarizer 49 and is incident on the liquid crystal display panel 11.

[0155] in addition, Figure 10 For polarized light incident perpendicular to the λ / 4 waveplate 270, the phase difference does not need to be λ / 4. Figure 10 In this structure, any phase retardation plate that allows polarized light to pass through twice, thus changing its phase by 90° (λ / 2), is sufficient. The thickness of the phase retardation plate can be adjusted accordingly based on the incident angle distribution of the polarized light. Furthermore, Figure 10 Similarly, in polarization transformation, the polarization design can be reversed compared to the above description (swapping the S polarization and P polarization).

[0156] Regarding the emitted light from the liquid crystal display panel 11, in typical TV-use devices, in the horizontal direction of the screen (using... Figure 12 (a) represented by the X-axis) and the vertical direction of the image (using) Figure 12 (b) representing the Y-axis all exhibit the same diffusion characteristics. In contrast, the diffusion characteristics of the emitted light beam from the liquid crystal display panel 11 in this embodiment are as follows: Figure 12As shown in Example 1, the viewing angle is 13 degrees when the brightness is 50% of that of a front-viewing device (0 degrees), which is about 1 / 5 of the 62 degrees of a typical TV device. Similarly, for the vertical viewing angle, the reflection angle and area of ​​the reflective light guide are optimized to make it asymmetrical, suppressing the upper viewing angle to about 1 / 3 of the lower viewing angle. As a result, the amount of image light heading towards the viewing direction is significantly increased compared to existing LCD TVs, with brightness more than 50 times greater.

[0157] Furthermore, if adopted Figure 12 The viewing angle characteristics shown in Example 2 indicate that the viewing angle is 5 degrees when the brightness is 50% of that of a front-viewing device (0 degrees), which is 1 / 12 of the 62 degrees of a typical TV device. Similarly, for the vertical viewing angle, the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized to make it uniform vertically and to suppress the viewing angle to about 1 / 12 of that of a typical TV device. As a result, the amount of image light heading towards the viewing direction is significantly increased compared to existing LCD TVs, with brightness more than 100 times greater.

[0158] By narrowing the viewing angle as described above, the amount of light beam heading in the viewing direction can be concentrated, thus significantly improving light utilization efficiency. As a result, even when using a typical LCD panel for TV applications, a significant increase in brightness can be achieved with the same power consumption by controlling the light diffusion characteristics of the light source device, enabling an image display device compatible with information display systems facing bright outdoor environments.

[0159] When using a large LCD panel, the light from the periphery of the screen is directed inwards so that it reaches the viewer when the viewer is facing the center of the screen, thereby improving the overall brightness of the screen. Figure 11 The convergence angles of the long and short sides of the panel were determined using the distance L between the viewer and the panel, and the panel size (16:10 aspect ratio) as parameters. In portrait mode, the convergence angle can be set accordingly for the short side. For example, with a 22″ panel used in portrait mode at a viewing distance of 0.8m, setting the convergence angle to 10 degrees will allow image light from the four corners of the screen to effectively reach the viewer.

[0160] Similarly, when viewing a 15″ panel in portrait mode at a viewing distance of 0.8m, setting the convergence angle to 7 degrees allows image light from the four corners of the screen to effectively reach the viewer. As described above, by directing image light from the periphery of the screen to the viewer in the most suitable position for viewing the center of the screen, based on the size of the LCD panel and whether it is used in portrait or landscape mode, the overall brightness of the screen can be improved.

[0161] As the basic structure, as described above Figure 9 The light source device is used to direct a beam of light with narrow-angle pointing characteristics onto the liquid crystal display panel 11. The brightness is modulated accordingly according to the image signal, so that the image information displayed on the screen of the liquid crystal display panel 11 is reflected on the retroreflector to obtain a spatial levitation image, which is then displayed outdoors or indoors via the transparent component 100.

[0162] Using the display device and light source device of one embodiment of the present invention described above, a spatial levitation image display device with higher light utilization efficiency can be realized.

[0163] <Example 2>

[0164] Hereinafter, as Embodiment 2 of the present invention, an example of the internal structure of the spatial levitation image display device will be described. Figure 13A , Figure 13B This is a diagram showing the main structural components of the spatial levitation image display device of Embodiment 2.

[0165] Example 2: Spatial Suspended Image Display Device 1000A Figure 13A , Figure 13B As shown in the example, the image light reflected by the retroreflector 5 is used to form a spatially suspended image 3 along the surface of the retroreflector 5 (in this example, along the xy plane). Figure 13A , Figure 13B The spatial levitation image display device 1000A shown is horizontally arranged with the side forming the spatial levitation image 3 facing upwards (i.e., the spatial levitation image 3 is formed above the retroreflector 5). In addition, the spatial levitation image display device 1000A is equipped with a linear prism sheet 1500 (e.g., BEF). Figure 13A In the example shown, the linear prism sheet 1500 is composed of one linear prism sheet 1501. Figure 13B In the example shown, the linear prism sheet 1500 is composed of two linear prism sheets 1502 and 1503.

[0166] In the spatial levitation image display device 1000A of Embodiment 2, 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 approximately parallel to each other at a predetermined interval. Therefore, the display device 1 and the spatial levitation image 3 are symmetrical about the retroreflector 5.

[0167] In addition, the display device 1 includes a liquid crystal display panel 11 and a light source device 13. The liquid crystal display panel 11 is configured from a small liquid crystal display panel with a screen size of approximately 5 inches to a large liquid crystal display panel exceeding 80 inches. The light source device 13 supplies light to the liquid crystal display panel 11, generating light with specific polarization and narrow-angle diffusion characteristics. The retroreflector 5 is configured as an array of corner reflectors, similar to that in Embodiment 1 (see Figure 1). Figure 2B wait).

[0168] As described above, the display device 1 and the retroreflector 5 are arranged facing each other, so the direction of travel of the light beam (image light) emitted from the display device 1 is approximately orthogonal to the surface of the retroreflector 5. However, in the spatial levitation image display device 1000A of Embodiment 2, a linear prism sheet 1500 is provided so that the image light emitted from the display device 1 is incident at a predetermined angle relative to the surface of the retroreflector 5. The linear prism sheet 1500 is an example of a beam travel direction changing sheet, and can also be expressed as a beam travel direction changing component.

[0169] As described in Embodiment 1, the incident angle α1 of the incident image light to the retroreflector 5 needs to be within the range of 45°±15°. When the incident angle α1 is 45°, the reflection efficiency of the incident image light on the retroreflector 5 is the highest. Therefore, in the spatial levitation image display device 1000A of Embodiment 2, in order to keep the incident angle α1 of the incident image light to the retroreflector 5 within the range of 45°±15°, a prism sheet 1500 for changing the travel direction of the light beam emitted from the display device 1 is provided between the display device 1 and the retroreflector 5.

[0170] Figure 13B In the example shown, the direction of image light emitted from the display device 1 is changed by using two linear prism sheets 1502 and 1503, so that the incident angle α1 of the image light on the retroreflector 5 is 45°±15°. That is, the two linear prism sheets 1502 and 1503 are arranged between the display device 1 and the retroreflector 5 in such a way that the incident angle α1 of the image light on the retroreflector 5 is 45°±15°. In addition, according to the optical characteristics of the retroreflector 5, the exit angle α2 of the image light emitted from the retroreflector 5 is the same as the incident angle α1.

[0171] 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 spatially suspended image 3 on the user side of the retroreflector 5.

[0172] As described above, the display device 1 and the spatial levitation image 3 are symmetrical about the surface of the retroreflector 5. Therefore, the spatial levitation image 3 is formed along the surface of the retroreflector 5. At this time, the image light emitted from the retroreflector 5 generates the spatial levitation image 3 at an angle α2 relative to the xy plane. That is, the viewer (user) can clearly see the spatial levitation image 3 when viewing it at an angle α2 in the direction of arrow A.

[0173] in addition, Figure 13A and Figure 13B In the image, multiple solid arrows represent image light incident from the liquid crystal display panel 11 onto the retroreflector 5, and multiple dashed arrows represent image light emitted from the retroreflector 5 and generating the spatial levitation image 3.

[0174] Furthermore, an image light control sheet 335 is disposed between the linear prism sheet 1500 and the retroreflector 5. By setting this image light control sheet 335, the user's recognition of the spatially suspended image 3 can be improved. The structure of the linear prism sheet 1500 and the image light control sheet 335 will be described in detail later.

[0175] Here, the linear prism sheet 1500 is positioned close to the liquid crystal display panel (hereinafter referred to as the "display panel") 11 of the display device 1. The linear prism sheet 1500 is preferably positioned as close as possible to the liquid crystal display panel 11 without contacting it. More specifically, the linear prism sheet 1500 is preferably positioned close to the liquid crystal display panel 11 such that the distance La between it and the liquid crystal display panel 11 is less than half the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0176] More specifically, in Figure 13A In the example shown, the linear prism sheet 1501 is positioned close to the liquid crystal display panel 11, such that the distance La between it and the liquid crystal display panel 11 is less than 1 / 4 of the distance Lb between the liquid crystal display panel 11 and the retroreflector 5. Furthermore, in Figure 13B In the example shown, the linear prism sheets 1502 and 1503 are arranged near the liquid crystal display panel 11 with the aforementioned interval La being less than 1 / 4 of the aforementioned interval Lb.

[0177] Furthermore, the image light control sheet 335 is also disposed close to the liquid crystal display panel 11 along with the linear prism sheet 1500. The image light control sheet 335 is preferably disposed as close as possible to the linear prism sheet 1500 without contacting it. More specifically, the image light control sheet 335 is preferably disposed close to the linear prism sheet 1500 such that the distance Lc between it and the liquid crystal display panel 11 is less than half of 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 can also be greater than half of the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0178] In addition, Figure 13A In the example shown, 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 on the side of the retroreflector 5 and the surface of the liquid crystal display panel 11 on the side of the retroreflector 5. Additionally, in Figure 13B In the example shown, 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 on the side of the retroreflector 5 and the surface of the liquid crystal display panel 11 on the side of the retroreflector 5. Similarly, the distance Lc between the image light control sheet 335 and the liquid crystal display panel 11 in this example refers to the distance between the surface of the image light control sheet 335 on the side of the retroreflector 5 and the surface of the liquid crystal display panel 11 on the side of the retroreflector 5.

[0179] Thus, in the spatial levitation image display device 1000A of Embodiment 2, by arranging the linear prism sheet 1500 close to the liquid crystal display panel 11 and the image light control sheet 335 also close to the liquid crystal display panel 11, the device can be made thinner. Furthermore, the spatial levitation image display device 1000A of Embodiment 2 is suitable for viewers (users) to view the spatial levitation image 3 from an obliquely upward direction along arrow A, thereby improving the user's recognition of the spatial levitation image 3.

[0180] In addition, Figure 13A , Figure 13B In the example shown, the spatial levitation image display device 1000A is arranged with the surfaces of the display device 1 and the retroreflector 5 facing upwards (z direction), but the arrangement direction of the spatial levitation image display device 1000A is not limited to this.

[0181] The spatial levitation image display device 1000A can also be, for example, as Figure 14A , Figure 14BAs shown, the spatial levitation image display device 1000A is arranged longitudinally with the side forming the spatial levitation image 3 as its front (i.e., the side facing the user 230). In other words, the spatial levitation image display device 1000A can be arranged longitudinally with the display device 1 and the retroreflector 5 along the vertical direction (in this example, along the xz plane). Furthermore, Figure 14A The device shown is to Figure 13A The device shown is arranged longitudinally, and the linear prism sheet 1500 is composed of one linear prism sheet 1501. Additionally, Figure 14B The device shown is to Figure 13B The device shown is arranged longitudinally, and the linear prism sheet 1500 is composed of two linear prism sheets 1502 and 1503.

[0182] exist Figure 14A and Figure 14B In the example shown, the linear prism sheet 1500 changes the direction of travel of the image light emitted from the liquid crystal display panel 11 in the y-direction (horizontal direction) to a downward direction. Furthermore, the image light reflected by the retroreflector 5 travels upward at an angle, displaying the suspended image 3 in the display space outside the retroreflector 5 (on the user 230 side).

[0183] Furthermore, when the spatial levitation image display device 1000A is vertically arranged, it is preferably configured such that the spatial levitation image 3 is formed at a position lower than the eye level of the user 230. The spatial levitation image display device 1000A is preferably installed on the ground or similar surface, so that when the user 230 views the spatial levitation image 3 while standing, their line of sight is directed diagonally downwards. Figure 14A , Figure 14B In the spatial levitation image display device 1000A shown, the light forming the spatial levitation image 3 travels in an upward direction. Therefore, by forming the spatial levitation image 3 at the aforementioned height, the user 230 can easily see the spatial levitation image 3 and can also easily operate the spatial levitation image 3 with their finger. For example, the spatial levitation image 3 can be easily applied to buttons on machines such as traffic lights and elevators.

[0184] In the case of a vertically positioned spatial levitation image display device 1000A, the linear prism sheet 1500 is also positioned close to the liquid crystal display panel 11 of the display device 1. In particular, the linear prism sheet 1500 is preferably configured as follows: Figure 14A and Figure 14B The plate is positioned close to the liquid crystal display panel 11, such that the distance La between the plate and the liquid crystal display panel 11 is less than half of the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0185] Furthermore, the image light control sheet 335 is preferably positioned close to the liquid crystal display panel 11 together with the linear prism sheet 1500. More specifically, as... Figure 14A and Figure 14B As shown, the image light control sheet 335 is preferably positioned close to the linear prism sheet 1500, such that the distance Lc between it and the liquid crystal display panel 11 is less than 1 / 2 of the distance Lb between the liquid crystal display panel 11 and the retroreflector 5.

[0186] Figures 15-18 yes Figure 14B The enlarged view of the spatial levitation image display device shown is an illustration of the linear prism sheet and the image light control sheet. Hereinafter, refer to this... Figures 15-18 A more detailed explanation of linear prism sheets and image light control sheets.

[0187] like Figure 15 and Figure 16 As shown, on the surface of the liquid crystal display panel 11 side of the linear prism sheets 1502 and 1503, a concave-convex portion 1506 is formed, including a protrusion 1504 and a recess (groove) 1505. In this example, the protrusion 1504 and the recess 1505 are continuously provided along the x-direction and alternately arranged along the y-direction. In other words, the surface of the liquid crystal display panel 11 side of the linear prism sheet 1500 is formed into a sawtooth shape by a first surface 1507 along the xy plane and a second surface 1508 inclined relative to the first surface 1507.

[0188] Linear prism sheets 1502 and 1503 are commercially available standard products with a thickness of approximately 2mm to 3mm. The tilt angle θd of the second face 1508 is approximately 10° to 30°. In addition, the pitch (so-called prism spacing) P1 of the multiple slots 1505 is approximately 1mm.

[0189] The image light is refracted by passing through the linear prism sheets 1502 and 1503 of this shape. The principal ray of the image light incident from the second surface 1508 onto the linear prism sheets 1502 and 1503 exits from the linear prism sheets 1502 and 1503 at a certain angle of refraction (also known as the exit angle).

[0190] For example, such as Figure 16 As shown, image light Li emitted from the liquid crystal display panel 11 along the xy plane is incident on one side of the concave-convex portion 1506 of the linear prism sheet 1502. The image light Li mainly enters the linear prism sheet 1502 from the second surface 1508 constituting the bottom surface of the concave portion 1505, where it is refracted with respect to the xy plane at a predetermined refraction angle θ1. After passing through the linear prism sheet 1502, the image light Li exits from the surface of the retroreflector plate 5 of the linear prism sheet 1502 at a predetermined refraction angle θ2 (>θ1).

[0191] Here, the material of each linear prism sheet 1501 to 1503 is a resin such as acrylic resin or polycarbonate. The refraction angles θ1 and θ2 are determined by the refractive index of these resin materials (e.g., refractive index = 1.49) and the tilt angle θd of the second surface 1508. Due to factors such as the limitations of processing accuracy caused by the material, the refraction angle θ2 of the image light Li when it exits from the linear prism sheets 1501 to 1503 is usually around 20°, but it is not particularly limited.

[0192] Furthermore, the image light Li emitted from the linear prism sheet 1502 is mainly incident on the second linear prism sheet 1503 from the second surface 1508. At this time, the image light Li is incident on the prism sheet 1503 with a specified refraction angle θ3 (>θ2) relative to the xy plane. The image light Li after passing through the linear prism sheet 1503 is emitted from the surface of the retroreflector 5 side of the linear prism sheet 1503 with a specified refraction angle θ4 (>θ3). That is, the image light Li after passing through the linear prism sheets 1502 and 1503 is emitted from the linear prism sheet 1503 with a specified exit angle ψ (=θ4).

[0193] Here, the refraction angle θ4 (e.g., the exit angle ψ) is twice the refraction angle θ2 (e.g., approximately 40°), and the image light Li is incident on the retroreflector 5 at this angle. Thus, in Figure 14B In the example shown, the incident angle α1 of the image light to the retroreflector 5 is 90° - 40° = 50°, which satisfies the condition that the incident angle α1 of the image light to the retroreflector 5 is within the range of 45° ± 15°. Furthermore, to make the incident angle α1 of the image light to the retroreflector 5 45°, the linear prism sheets 1502 and 1503 can be designed with a refraction angle θ2 = 22.5°.

[0194] However, as Figure 15 and Figure 16 As illustrated, the image light Li emitted from a predetermined (arbitrary) point on the liquid crystal display panel 11 travels toward the linear prism sheet 1502, while simultaneously diverging at a predetermined divergence angle φa. The expansion width (also referred to as the "diameter of the image light Li") Wa of the image light Li increases as it approaches the linear prism sheet 1502. Thus, 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 expansion width Wa1.

[0195] As described above, each of the linear prism sheets 1501 to 1503 is positioned close to the liquid crystal display panel 11, therefore the spread width Wa1 of the image light Li incident on the linear prism sheets 1501 to 1503 is relatively narrow. The spread width Wa1 of the image light Li is not particularly limited, but it is preferable to be narrower than a preset width.

[0196] Specifically, the extension width Wa1 of the image light Li is preferably narrower than three times the aforementioned pitch P1. For example, as Figure 15 As shown, the spread width Wa1 (Wa) of the image light Li on the surface of the liquid crystal display panel 11 side of the linear prism sheet 1502 (in this example, the surface including the vertices of each protrusion 1504) is preferably narrower than three times the pitch P1 mentioned above. Furthermore, the spread width Wa1 of the image light incident on the linear prism sheet 1502 is, for example, as shown below. Figure 16 As shown, it is preferable to have a narrower pitch than the aforementioned pitch P1.

[0197] In other words, the linear prism sheet 1502 is preferably disposed close to the liquid crystal display panel 11, such that the spread width Wa1 of the image light Li incident on the linear prism sheet 1502 is narrower than three times the pitch P1, and in particular, the spread width Wa1 is narrower than the pitch P1. That is, it is preferable to arrange the linear prism sheet 1502 close to the liquid crystal display panel 11 so that the image light Li emitted and diffused from a predetermined point on the liquid crystal display panel 11 can be incident on the linear prism sheet 1502 from the second surface 1508 constituting the bottom surface of the recess 1505.

[0198] Similarly, the linear prism sheet 1503 is preferably positioned close to the linear prism sheet 1502, such that the spread width Wa1 of the image light Li incident on the linear prism sheet 1503 is narrower than 3 times the pitch P1, and in particular, the spread width Wa1 is narrower than the pitch P1.

[0199] By arranging the linear prism sheet 1500 close to the surface of the display device 1, it is easy to increase the incident angle α1 of the image light Li onto the retroreflector 5. That is, the image light Li emitted by the display device 1 can be incident on the retroreflector 5 at an appropriate incident angle α1. Furthermore, the prism height 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 (e.g., two) linear prism sheets 1502 and 1503 close to the display device 1, it is easy to increase the incident angle α1 of the image light Li onto the retroreflector 5.

[0200] In this example, the two linear prism sheets 1502 and 1503 have the same shape, but linear prism sheets with different shapes can also be combined. Furthermore, a light-shielding layer can be provided on the first surface (the surface along the yz plane) 1507 of the linear prism sheets 1502 and 1503 to block the image light Li incident on the linear prism sheets 1502 and 1503 from the first surface 1507, thereby preventing the generation of excess light. Furthermore, the above describes an example where the linear prism sheet 1500 of the spatial levitation image display device 1000A is composed of one linear prism sheet 1501 or two linear prism sheets 1502 and 1503, but the structure of the linear prism sheet 1500 is not particularly limited. The linear prism sheet 1500 can also be composed of three or more prism sheets, as long as the image light Li can achieve the desired incident angle α1.

[0201] However, in the spatial levitation image display device 1000A of Embodiment 2, because the retroreflector 5 and the display device 1 are positioned directly opposite each other, for example... Figure 14A and Figure 14B As shown, when a viewer (user) looks down at the spatial levitation image 3, the image displayed on the display surface of the liquid crystal display panel 11 appears to overlap with the spatial levitation image 3, which may reduce the recognizability of the spatial levitation image 3. Therefore, in the spatial levitation image display device 1000A of Embodiment 2, an image light control sheet 335 is provided on the image light emitting surface side of the linear prism sheet 1500.

[0202] The function of the image light control sheet 335 is to prevent the image displayed on the liquid crystal display panel 11 from appearing to overlap with the spatially suspended image 3 when the viewer (user) looks down at the spatially suspended image 3 in the direction of arrow A. It is configured so that the main ray of the image light Li, whose direction of travel has changed due to the linear prism sheet 1500, can pass through the image light control sheet. The spatially suspended image 3 is formed using the image light Li that has passed through the image light control sheet 335. In other words, the image light control sheet 335 functions to allow the image light Li to pass through while simultaneously blocking the liquid crystal display panel 11.

[0203] like Figure 16 and Figure 17 As shown, in the image light control sheet 335, a light-transmitting portion 336 made of transparent silicon and a light-shielding portion 337 made of black silicon of a predetermined thickness are alternately arranged at a predetermined interval, and a sandwich structure is formed by depositing synthetic resin (not shown) on the two surfaces on which the image light Li is incident or emitted. Alternatively, a field-viewing angle control film (VCF) can be used as the aforementioned image light control sheet 335, for example.

[0204] Figure 16 and Figure 17 In the example shown, the light-transmitting portion 336 and the light-shielding portion 337 constituting the image light control sheet 335 are configured to be continuously arranged along the x-direction and alternately arranged along the z-direction (vertical direction). The light-shielding portion 337 functions as a so-called venetian blind and is arranged at a predetermined tilt angle γ relative to the direction of travel (horizontal direction) of the image light Li emitted from the liquid crystal display panel 11. In other words, the light-shielding portion 337 is arranged at a predetermined tilt angle γ in the same tilt direction as the main ray direction of the image light Li emitted from the linear prism sheet 1503.

[0205] Therefore, the image light Li emitted from the linear prism sheet 1503 can pass through 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 can be transmitted through the light-transmitting portion 336. Then, the spatial levitation image 3 is generated using the image light Li transmitted through the light-transmitting portion 336. On the other hand, when the user looks down at the spatial levitation image 3 in the direction of arrow A, most of the image displayed on the liquid crystal display panel 11 is blocked by the light-shielding portions 337 of the image light control sheet 335.

[0206] Therefore, when a user looks down at the spatial floating image 3 along the direction of arrow A, the image displayed on the display surface of the liquid crystal display panel 11 can be prevented from appearing to overlap with the spatial floating image 3, and the user's recognition of the spatial floating image 3 is improved.

[0207] in addition, Figure 16 and Figure 17 The example shown illustrates an image light control sheet 335 with 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.

[0208] and, Figure 16 In the example shown, the image light control sheet 335 is arranged substantially parallel to the linear prism sheet 1500 (1502, 1503), but the image light control sheet 335 is preferably arranged at an angle relative to the surface of the linear prism sheet 1500 as needed.

[0209] 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 spatial levitation image 3 as described above, the user's line of sight (direction A) when looking down at the spatial levitation image 3 is preferably outside the range of the viewing angle β of the image light control sheet 335.

[0210] The viewing angle β of the image light control sheet 335 refers to the angle of the visible range between the following two line segments: one along the surface of the light-shielding portion 337 (which can also be described as the boundary between the light-transmitting portion 336 and the light-shielding portion 337), and the other connecting the end of the light-shielding portion 337 on the image light incident side to the end of the adjacent light-shielding portion 337 on the image light emitting side. In this example, the viewing angle β of the image light control sheet 335 is as follows: Figure 17 As shown in the example, the angle of the visible range is formed by line segment L1 and line segment L2, where line segment L1 is a line segment along the surface of the light-shielding part 337b, and line segment L2 is a line segment that connects the end of the light-shielding part 337b on the image light incident side to the end of the light-shielding part 337c adjacent to the light-shielding part 337b on the image light emitting side.

[0211] And, as Figure 17As shown, when the user's line of sight is in the direction of arrow A, which forms a predetermined angle θu1 relative to the xy plane, the aforementioned angle θu1 is preferably greater than the angle θy of the aforementioned line segment L2 relative to the xy plane. That is, the image light control sheet 335 is preferably configured such that the angle θy is smaller than the line of sight angle θu1.

[0212] In this way, the image light control sheet 335 is configured such that the user's line of sight is outside the viewing angle β of the image light control sheet 335, thereby preventing the image displayed on the display surface of the liquid crystal display panel 11 from appearing to overlap with the spatial floating image 3 when the viewer (user) looks down at the spatial floating image 3 in the direction of arrow A, thus improving the recognizability of the spatial floating image 3.

[0213] In addition, Figure 17 In the example shown, because the angle θy is slightly larger than the viewing angle θu1, when the user looks down at the spatial floating image 3, the image displayed on the display surface of the liquid crystal display panel 11 may appear to overlap with the spatial floating image 3.

[0214] Furthermore, from the viewpoint of improving the brightness of the spatially suspended image 3, the image light control sheet 335 is preferably configured such that the main ray of the image light Li emitted from the linear prism sheet 1503 can easily pass through it. That is, the image light control sheet 335 is preferably configured to minimize obstruction of the main ray of the image light Li emitted from the linear prism sheet 1503. Specifically, the image light control sheet 335 is preferably configured such that the tilt angle γ of the light-shielding portion 337 relative to the xy plane is the same as the emission angle ψ of the image light Li emitted from the linear prism sheet 1503.

[0215] For example, Figure 15 and Figure 16 In the structure shown, the emission angle ψ of the image light Li is not consistent with the tilt angle γ of the light-shielding part 337, and the emission angle ψ of the image light Li is slightly larger than the tilt angle γ of the light-shielding part 337. Therefore, a portion of the image light Li, which diverges at a divergence angle φa, is easily blocked by the light-shielding part 337, and the brightness of the spatially suspended image 3 may be insufficient.

[0216] Therefore, based on this viewpoint, the image light control sheet 335 is preferably configured at an angle relative to the surface of the linear prism sheet 1500. For example, the image light control sheet 335 is as follows: Figure 18 As shown, it is preferably configured to be tilted at an angle θx relative to the surface of the linear prism sheet 1503. More specifically, the image light control sheet 335 is preferably configured to be tilted at an angle θx such that the relationship between the tilt angle θx, the emission angle ψ of the image light Li emitted from the linear prism sheet 1503, and the tilt angle γ of the light-shielding part 337 satisfies the relationship θx = ψ - γ (condition 1).

[0217] Therefore, the brightness (luminosity) of the spatial levitation image 3 can be improved, and the recognizability of the spatial levitation image 3 can be further improved.

[0218] However, even if condition 1 is met, if the divergence angle φa of the image light Li is too large, a portion of the image light Li may still be blocked by the light-shielding part 337. Therefore, the divergence angle φa of the image light Li is preferably such that it will not be blocked by the light-shielding part 337. Specifically, the emission angle ψ of the image light Li, the divergence angle φa of the image light Li, and the viewing angle β of the image light control sheet 335 preferably satisfy the relationship ψ + φa ≤ β (condition 2). Furthermore, the tilt angle γ of the light-shielding part 337 and the viewing angle β of the image light control sheet 335 preferably satisfy the relationship 2γ ≈ β (condition 3).

[0219] 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 plate 335, and the tilt angle γ of the light-shielding part 337, the above conditions 1 to 3 can be satisfied. For example, by setting the values ​​of the emission angle ψ, the divergence angle φa, the tilt angle θx, and the tilt angle γ to... Figure 19 The values ​​shown in Examples 1 and 2 satisfy conditions 1 to 3 above.

[0220] By satisfying conditions 1 to 3, when a user views the suspended image 3 from above, 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 suspended image 3, while simultaneously increasing the brightness of the suspended image 3. As a result, the user's ability to recognize the suspended image 3 can be further improved.

[0221] As explained above, the structure of the spatial levitation image display device 1000A according to Embodiment 2 enables miniaturization, especially thinning, of the device (e.g., Figure 14A and Figure 14B The thinning effect along the y-axis allows it to be housed in a limited space. Therefore, it is possible to provide a spatially suspended image display device that offers good visibility for viewers and possesses sufficiently high brightness for practical use.

[0222] In this embodiment, by displaying high-resolution and high-brightness image information in a suspended state in space, users can operate the system without feeling uneasy about the risk of contact transmission of infectious diseases. If this embodiment's technology is used in a system with an uncertain number of users, the risk of contact transmission of infectious diseases can be reduced, providing a contactless user interface that can be used without anxiety. This contributes to the United Nations' Sustainable Development Goals (SDGs) of "Good Health and Well-being."

[0223] Furthermore, in this embodiment, by reducing the divergence angle of the emitted image light and unifying it into a specific polarization, only the reflected light that would normally be reflected by the return reflector is reflected efficiently. Therefore, the light utilization efficiency is high, resulting in a bright and clear spatial levitation image. According to this embodiment, a contactless user interface with significantly reduced power consumption and excellent usability can be provided. This contributes to the United Nations Sustainable Development Goals (SDGs) for "9. Industries, Innovation and Infrastructure" and "11. Sustainable Cities and Communities".

[0224] Various embodiments have been described in detail above, but the present invention is not limited to the above embodiments and includes various modifications. For example, the above embodiments have described the entire system in detail for ease of understanding of the present invention, but are not limited to having all the described structures. In addition, a part of the structure of one embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of one embodiment. Furthermore, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0225] Explanation of reference numerals in the attached figures

[0226] 1... Display device, 2... Retroreflector (retroreflective reflector), 3... Spatial image (spatial levitation image), 105... Window glass, 100... Transparent component, 101... Polarization separation component, 101B... Polarization separation component, 12... Absorption polarizer, 13... Light source device, 54... Light direction conversion panel, 151... Retroreflector, 102, 202... LED substrate, 203... Light guide, 205, 271... Reflector, 206, 270... Phase retardation plate, 230... User, 335... Image light control plate, 3 36……Light-transmitting part, 337……Light-shielding part, 1000, 1000A……Space-suspended image display device, 1110……Control unit, 1160……Image control unit, 1180……Camera unit, 1102……Image display unit, 1350……Airborne operation detection unit, 1351……Airborne operation detection sensor, 1500 (1501~1503)……Linear prism sheet (beam travel direction changing sheet), 1504……Protrusion, 1505……Recess (groove), 1506……Concave-convex part, 1507……First surface, 1508……Second surface.

Claims

1. An aerial levitation image display device, characterized in that, include: Display panel, which displays images; A retroreflector reflects image light from the display panel, using the reflected light to display a real, suspended image in mid-air; and A beam travel direction changing plate, disposed between the display panel and the retroreflector, alters the travel direction of image light from the display panel. The beam travel direction changing plate is positioned close to the display panel.

2. The aerial levitation image display device as described in claim 1, characterized in that: The beam travel direction changing plate has grooves formed at a predetermined pitch on its surface. It is configured such that the spread width of the image light emitted from a predetermined point on the display panel when incident on the beam travel direction changing plate is narrower than the pitch.

3. The aerial levitation image display device as described in claim 1, characterized in that: The beam travel direction changing plate has grooves formed at a predetermined pitch on its surface. It is configured such that the spread width of the image light emitted from a predetermined point on the display panel when incident on the beam travel direction changing plate is narrower than 3 times the pitch.

4. The aerial levitation image display device as described in claim 2, characterized in that: Includes multiple beam travel direction changing plates, Each of the beam travel direction changing plates is configured such that the spread width of the image light incident on the beam travel direction changing plate is narrower than the pitch.

5. The aerial levitation image display device as described in claim 1, characterized in that: The beam travel direction changing plate is positioned close to the display panel such that the distance between the beam travel direction changing plate and the display panel is less than 1 / 2 of the distance between the display panel and the retroreflector.

6. The aerial levitation image display device as described in claim 5, characterized in that: It also includes an image light control plate disposed between the beam travel direction changing plate and the retroreflector. The image light control sheet is positioned close to the beam travel direction changing sheet, such that the spacing between the image light control sheet and the display panel is less than 1 / 2 of the spacing between the display panel and the retroreflector.

7. The aerial levitation image display device as described in claim 6, characterized in that: The image light control plate allows the main ray of the image light, whose direction of travel has changed due to the beam travel direction change plate, to be transmitted.

8. The aerial levitation image display device as described in claim 6, characterized in that: The image light control sheet is composed of alternating light-transmitting and light-blocking portions. The emission angle ψ of the image light emitted from the beam travel direction change plate, the divergence angle φa of the image light, and the visible angle β of the image light that can be seen through the light-transmitting part satisfy the relationship ψ+φa≤β.

9. The aerial levitation image display device as described in claim 8, characterized in that: The image light control plate is configured to be tilted at an angle θx relative to the surface of the beam travel direction changing plate. The tilt angle θx of the image light control sheet, the emission angle ψ of the image light, and the tilt angle γ of the light-shielding part satisfy the relationship ψ-γ=θx.

10. The aerial levitation image display device as described in claim 1, characterized in that: The display panel is configured along the vertical direction. The beam travel direction changing plate changes the travel direction of the image light from the display panel to be diagonally downward. The suspended image in the air is displayed using the image light that travels obliquely upwards after being reflected by the return reflector.

Images