Spatial floating image display device

Abstract

To obtain a space floating video display device that can obtain a space floating video with less ghost and influence of external light, has high visibility, and is compact, which, according to the present invention, contributes to "3 Ensure healthy lives and promote well-being for all at all ages," "9 Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and "11 Make cities and human settlements inclusive, safe, resilient and sustainable" in Sustainable Development Goals.SOLUTION: A space floating video display device comprises: a liquid crystal display panel as a video source; a light source device that supplies light in a specific polarization direction to the liquid crystal display panel; and a retroreflective member that is provided with a phase difference plate on a retroreflective surface. A polarization separation member is provided in a space connecting the liquid crystal display panel and the retroreflective member. The polarization separation member once transmits video light of a specific polarized wave from the liquid crystal display panel toward the retroreflective member, performs polarization conversion with the retroreflective member to convert the polarized wave of the video light into the other polarized wave, thereby causing the video light to be reflected on the polarization separation member, and displays a space floating video light being a real image on the opposite side of the video source in a transparent member through which the video light of the specific polarized wave is transmitted.SELECTED DRAWING: Figure 6A

Description

Technical Field

[0001] The present invention relates to a spatial floating image display device. position

Background Art

[0002] As an example of a spatial floating image display device, Patent Document 1 discloses that "the CPU of the information processing device includes an approach direction detection unit that detects the approach direction of the user to the image formed in the air, an input coordinate detection unit that detects the coordinates where an input is detected, an operation reception unit that processes the reception of an operation, and an operation screen update unit that updates the operation screen according to the received operation. When the user approaches the image from a predetermined direction, the CPU receives the movement of the user as an operation and executes processing according to the operation (summary excerpt)."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although the spatial floating image display device of Patent Document 1 described above can improve the operability of the spatial floating image, it does not consider improving the visual resolution or contrast of the spatial floating image, and there is a situation where further improvement in image quality is required.

[0005] The present invention has been made in view of the above situation, and an object thereof is to provide a spatial floating image display device that can display a suitable and highly visible spatial floating image.

Means for Solving the Problems

[0006] ​In order to solve the above problems, for example, the configuration described in the claims is adopted. This application includes a plurality of means for solving the above problems. For example, a spatial floating image display device for forming a spatial floating image, including a display panel, a light source device that supplies light with a specific polarization direction to the display panel, a retroreflective member provided with a retardation plate on the retroreflective surface, a polarization separation member in the space connecting the display panel and the retroreflective member, a housing, and a transparent member provided as a window portion of the housing. The polarization separation member once transmits the video light of a specific polarization wave from the display panel toward the retroreflective member, and after polarization conversion by the retroreflective member and conversion to the other polarization wave, it is reflected by the polarization separation member, and the video light reflected by the polarization separation member passes through the transparent member which is the window portion, and a spatial floating image which is a real image is displayed outside the window portion. The light incident from the display panel to the retroreflective member is inclined obliquely upward with respect to the horizontal and the retroreflective member is arranged such that the reflecting surface of the retroreflective member inclines downward with respect to the vertical direction .

Advantages of the Invention

[0007] According to the present invention, a spatial floating image display device capable of displaying a suitable and highly visible spatial floating image can be realized. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0008]

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Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the description of the embodiments, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification. In addition, in all the drawings for explaining the present invention, those having the same function are given the same reference numerals, and the repeated description thereof may be omitted. In the following description of the embodiments, the video floating in space is expressed by the term "space-floating video". Instead of this term, it may be expressed as "air-floating video", "spatially floating optical image of the display video", or "air-floating optical image of the display video". The term "space-floating video" used in the description of the embodiments is used as a representative example of these terms.

[0010] The following embodiments relate to a space-floating video display system capable of, for example, transmitting a video by video light from a large-area video light source through a transparent member that partitions a space such as the glass of a show window and displaying it as a space-floating video inside or outside the store (space). The present invention also relates to a large-scale digital signage system configured by using a plurality of such space-floating video display systems.

[0011] According to the following embodiments, for example, high-resolution video information can be displayed in a state of being spatially floating on the glass surface of a show window or a light-transmissive plate material. At this time, by reducing the divergence angle of the emitted video light, that is, making it an acute angle, and further aligning it with a specific polarization, only the regular reflected light can be efficiently reflected to the retroreflective member, so the light utilization efficiency is high. In addition to the main spatially floating video that has been a problem in the conventional retroreflective method, the ghost images that occur can be suppressed, and a clear spatially floating video can be obtained. Further, an apparatus including the light source of the present embodiment can provide a novel and highly usable spatially floating video display system capable of significantly reducing power consumption. Also, for example, a floating video display system for a vehicle capable of one-way spatially floating video display that can be visually recognized outside the vehicle through a shield glass including a front glass, a rear glass, or a side glass of the vehicle can be provided.

[0012] On the other hand, in a conventional spatially floating video display system, an organic EL panel or a liquid crystal display panel is combined with a retroreflective member as a high-resolution color display video source. In a spatially floating video display device according to the prior art, since the video light diffuses at a wide angle, in addition to the reflected light that is regularly reflected because the retroreflective part is a hexahedron, as shown in FIG. 3, ghost images are generated by the video light incident obliquely on the retroreflective member (retroreflective sheet) 2, deteriorating the image quality of the spatially floating video. Since the retroreflective member shown as the prior art is a hexahedron, a plurality of ghost images from the first ghost image G1 to the sixth ghost image G6 are generated in addition to the regular image R1 of the spatially floating video as shown in FIG. 5. For this reason, there has been a major security issue in that ghost images, which are the same spatially floating video, are monitored not only by viewers.

[0013] In addition, in the spatially floating video obtained by reflecting the video light from a video display device having a narrow-angle directivity characteristic, which will be described later, by a retroreflective member, blurring was visually recognized for each pixel of the liquid crystal display panel as shown in FIG. 4 in addition to the above-described ghost images.

[0014] <Spatially Floating Video Display System (1)> FIG. 1 is a diagram showing an example of a usage form of a spatial floating image display system according to an embodiment of the present invention. FIG. 1(A) is a diagram showing the overall configuration of the spatial floating image display system according to the present embodiment. For example, in a store or the like, a space is partitioned by a show window (window glass 105) which is a translucent member such as glass. According to the spatial floating information display system of the present embodiment, it is possible to display a floating image in one direction with respect to the outside of the store (space) through such a transparent member. Specifically, light of a specific polarization with a narrow-angle directivity characteristic is emitted as an image light beam from the image display device 1, once enters the retroreflective member 2, is retroreflected, passes through the window glass 105, and forms a real image, an aerial image (spatial floating image 3), outside the store. In FIG. 1, the inside (inside the store) of the window glass 105 is shown as the depth direction, and the outside (for example, a sidewalk) is shown as the front. On the other hand, by providing means for reflecting a specific polarization wave on the window glass 105, it is also possible to form an aerial image at a desired position inside the store.

[0015] FIG. 1(B) is a block diagram showing the configuration of the above-described image display device 1. The image display device 1 includes an image display unit 1a that displays an original image of an aerial image, an image control unit 1b that converts the input image according to the resolution of the panel, an image signal reception unit 1c that receives an image signal, and a reception antenna 1d. The image signal reception unit 1c corresponds to a wired input signal such as an HDMI (High-Definition Multimedia Interface: registered trademark) input and a wireless input signal such as Wi-Fi (Wireless Fidelity: registered trademark), and also functions alone as an image reception and display device, and can also display video information from a tablet, a smartphone, or the like. Furthermore, if a laptop PC or the like is connected, it is possible to provide capabilities such as calculation processing and video analysis processing.

[0016] FIG. 2 is a diagram showing an example of the main configuration and the retroreflective unit configuration of a spatial floating image display system according to an embodiment of the present invention. Using FIG. 2, the configuration of the spatial floating image display system will be described more specifically. As shown in FIG. 2(A), a video display device 1 that diverges video light of a specific polarization in a narrow angle is provided in an oblique direction of a transparent member 100 such as glass. The video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having a narrow-angle diffusion characteristic.

[0017] The video light of a specific polarization from the video display device 1 is reflected by a polarization separation member 101 having a film that selectively reflects the video light of the specific polarization provided on the transparent member 100 (in the figure, the polarization separation member 101 is formed in a sheet shape and adhered to the transparent member 100), and enters the retroreflective member 2. A λ / 4 plate 21 is provided on the video light incident surface of the retroreflective member. The video light is polarization-converted from a specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, when entering and exiting the retroreflective member 2. Here, since the polarization separation member 101 that selectively reflects the video light of the specific polarization has the property of transmitting the polarization of the other polarization that has been polarization-converted, the video light of the specific polarization after polarization conversion passes through the polarization separation member 101. The video light that has passed through the polarization separation member 101 forms a spatial floating image 3 that is a real image outside the transparent member 100.

[0018] Note that the light forming the spatial floating image 3 is a set of light rays that converge from the retroreflective member 2 to the optical image of the spatial floating image 3, and these light rays continue to travel even after passing through the optical image of the spatial floating image 3. Therefore, the spatial floating image 3 is an image with high directivity, unlike the diffused video light formed on a screen by a general projector or the like. Therefore, in the configuration of FIG. 2, when the user views from the direction of arrow A, the spatial floating image 3 is viewed as a bright image, but when another person views from the direction of arrow B, the spatial floating image 3 cannot be viewed as an image at all. This characteristic is very suitable for use in a system that displays an image that requires high security or an image with high confidentiality that needs to be concealed from a person facing the user.

[0019] Depending on the performance of the retroreflective member 2, the polarization axes of the video light after reflection may become uneven. In this case, some of the video light with uneven polarization axes is reflected by the polarization separation member 101 described above and returns to the video display device 1. This light may be retroreflected by the video display surface of the liquid crystal display panel 11 constituting the video display device 1, generating a ghost image and degrading the image quality of the floating image in space. Therefore, in this embodiment, an absorption-type polarizing plate 12 is provided on the video display surface of the video display device 1. The video light emitted from the video display device 1 is transmitted through the absorption-type polarizing plate 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorption-type polarizing plate 12, thereby suppressing the above-mentioned retroreflection. Thereby, it is possible to prevent the degradation of the image quality due to the ghost image of the floating image in space.

[0020] The above-described polarization separation member 101 may be formed of, for example, a reflective polarizing plate or a metal multilayer film that reflects a specific polarization wave.

[0021] Next, FIG. 2(B) shows the surface shape of the retroreflective member 2 manufactured by Nippon Kabite Kogyo Co., Ltd. used in this study as a typical retroreflective member 2. The light beam incident on the inside of the retroreflective portion 2a composed of regularly arranged hexagonal prisms is reflected by the wall surface and the bottom surface of the hexagonal prism and emitted as retroreflected light in the direction corresponding to the incident light to form the normal image R1 shown in FIG. 5. On the other hand, as shown in FIG. 3, depending on the video light obliquely incident on the retroreflective member 2 among the video light from the video display device 1, a ghost image (G1 to G6 in FIG. 5) is formed separately from the normal image R1.

[0022] Therefore, based on the video displayed on the video display device 1 of the present invention, a spatial floating image 3, which is a real image, is displayed without forming a ghost image. The resolution of this spatial floating image 3 depends greatly on the outer diameter D and pitch P of the retroreflective portion 2a of the retroreflective member 2 shown in FIG. 2(B) in addition to the resolution of the liquid crystal display panel 11. For example, when a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel 11 is used, even if one pixel (one triplet) is about 80 μm, for example, if the diameter D of the retroreflective portion 2a is 240 μm and the pitch is 300 μm, one pixel of the spatial floating image 3 corresponds to 300 μm. Therefore, the effective resolution of the spatial floating image 3 is reduced to about 1 / 3. Therefore, in order to make the resolution of the spatial floating image 3 equivalent to the resolution of the video display device 1, it is desirable to make the diameter and pitch of the retroreflective portion 2a closer to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moiré due to the pixels of the retroreflective member 2 and the liquid crystal display panel 11, it is advisable to design the pitch ratio of each to be outside an integer multiple of one pixel. Also, it is advisable to arrange the shape so that none of the sides of the retroreflective portion 2a overlap with any of the sides of one pixel of the liquid crystal display panel 11.

[0023] In order to improve visibility, the inventors created a video display device 1 by combining a liquid crystal display panel with a pixel pitch of 40 μm and a light source with a narrow divergence angle (divergence angle of 15°) of the present invention, and obtained the relationship between the allowable amount of blurring l of the image of the spatial floating image and the pixel size L through experiments. The experimental results are shown in FIG. 4. It was found that the amount of blurring l at which visibility deteriorates is preferably 40% or less of the pixel size, and is hardly noticeable if it is 15% or less. The surface roughness of the reflecting surface at which the amount of blurring l at this time becomes the allowable amount is such that the average roughness is 160 nm or less in the range of a measurement distance of 40 μm, and it was found that the surface roughness of the reflecting surface is preferably 120 nm or less in order to obtain a less noticeable amount of blurring l. Therefore, it is desirable to reduce the surface roughness of the above-mentioned retroreflective member and make the surface roughness including the reflective film forming the reflecting surface and its protective film not exceed the above-mentioned value.

[0024] On the one hand, in order to manufacture the retroreflective member 2 at a low cost, it is advisable to use the roll press method for molding. Specifically, it is a method of aligning the retroreflective portions 2a and shaping them on a film. The reverse shape of the shape to be shaped is formed on the roll surface, an ultraviolet curable resin is applied on the base material for fixing, and the resin is passed between the rolls to shape the required shape and then irradiated with ultraviolet rays to cure it, thereby obtaining the retroreflective member 2 with the desired shape.

[0025] The video display device 1 of the present invention has a structure in which the video is less likely to be incident obliquely on the above-described retroreflective member 2 by the liquid crystal display panel 11 and the light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics, which will be described in detail later. Even if ghosting occurs, the brightness is low, resulting in an excellent system.

[0026] <Spatial floating video display system (2)> FIG. 6A is a diagram showing another example (second example) of the main configuration of the spatial floating video display system according to an embodiment of the present invention. The video display device 1 includes a liquid crystal display panel 11 as a video display element and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics. The liquid crystal display panel 11 is composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. For example, a polarization separation member 101 such as a reflective polarizing plate reflects the video light from the liquid crystal display panel toward the retroreflective member 2.

[0027] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2. By allowing the video light to pass through twice to perform polarization conversion and converting a specific polarization wave into the other polarization wave, the light is transmitted through the polarization separation member 101, and a spatial floating image 3, which is a real image, is displayed outside the transparent member 100. An absorption-type polarizing plate is provided on the outer light incident surface of the transparent member 100. In the above-described polarization separation member 101, since the polarization axis becomes uneven due to retroreflection, some of the video light is reflected and returns to the video display device 1. This light is reflected again by the video display surface of the liquid crystal display panel 11 constituting the video display device 1, generating a ghost image and significantly degrading the image quality of the spatial floating image 3. Therefore, in this embodiment, an absorption-type polarizing plate 12 is provided on the video display surface of the video display device 1 to transmit the video light and absorb the above-described reflected light, thereby preventing degradation of the image quality due to the ghost image of the spatial floating image 3.

[0028] Furthermore, in order to reduce degradation of the image quality caused by sunlight or illumination light outside the set, it is preferable to provide an absorption-type polarizing plate 112 on the surface of the transparent member 100. Further, when external light enters the retroreflective member 2, a strong ghost image is generated, so a configuration is adopted in which the fourth light-shielding member 25 prevents the incidence of external light. The polarization separation member 101 is formed of a reflective polarizing plate or a metal multilayer film that reflects a specific polarization wave.

[0029] A second light-shielding member 23 and a third light-shielding member 24 that block oblique video light other than the normal video light that forms the spatial floating image are provided between the polarization separation member 101 and the liquid crystal display panel 11. Also, a first light-shielding member 22 that blocks oblique video light other than the normal video light is provided between the retroreflective member 2 and the polarization separation member 101. Further, as described above, a fourth light-shielding member 25 is also provided so that external light does not directly enter the retroreflective member 2, blocking the oblique light that generates the ghost image. As a result, the generation of the ghost image can be suppressed.

[0030] The inventors confirmed through experiments that by installing the third light-shielding member 24 and the second light-shielding member 23 together in the space between the liquid crystal display panel 11 and the polarization separation member 101, the light-shielding effect can be enhanced. In this experiment, the inner diameters of the second light-shielding member 23 and the third light-shielding member 24 are set to 110% in terms of area with respect to the region through which the regular video light beam forming the spatial floating image passes, so that the component accuracy can be created and assembled within the range of mechanical tolerances. Furthermore, in order to further reduce the occurrence of ghost images, if it is 104% or less with respect to the region through which the regular video light beam of the above-mentioned light-shielding member passes, the occurrence of ghost images can be suppressed to a level without practical problems. On the other hand, for the first light-shielding member 22 provided between the retroreflective member 2 and the polarization separation member 101, if the distance L1 between the first light-shielding member 22 and the retroreflective member 2 is 50% or less with respect to the distance between the retroreflective member 2 and the polarization separation member 101, the occurrence of ghost images can be further reduced, and when it is 30% or less, it can be reduced to a level without practical problems visually. Furthermore, by installing the fourth light-shielding member 25 provided so as to surround the retroreflective member 2 together with the first light-shielding member 22, the second light-shielding member 23, and the third light-shielding member 24, the ghost level can be further reduced.

[0031] The cross-sectional shape of the light-shielding member in FIG. 6A is approximately the same size as the effective area of the light-shielding member with respect to the region through which the regular video light beam forming the spatial floating image passes (corresponding to the region through which the video light beam in the absorption-type polarizing plate 112 passes in this embodiment). It is better to provide a beam toward the inner surface and reflect the abnormal light forming the ghost image multiple times on the surface of the beam to absorb the abnormal light. The region through which the regular video light beam passes with respect to the outer frame of the light-shielding member is made small and has the same area as the surface inscribed by the beam.

[0032] Even if the shape of the retroreflective member 2 is a concave or convex surface with a radius of curvature of 200 mm or more from the planar shape facing the image display device 1, and a ghost image is generated by the oblique image light reflected by the retroreflective member 2, the ghost image generated after reflection may be separated from the viewer's field of view so that it cannot be monitored. A new problem occurs in that the peripheral light amount of the spatially floating image 3, which can reduce the amount of regularly reflected light, decreases at the periphery of the retroreflective member 2 having a radius of curvature of 100 mm or less. Therefore, in order to reduce the ghost image to a level that is not a problem in practical use, it is advisable to select and apply, or use in combination, the above-described technical means.

[0033] <Spatial floating image display system (3)> FIG. 6B is a diagram showing another example (third example) of the main configuration of the spatial floating image display device according to an embodiment of the present invention. The image display device 1 includes a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization having a narrow-angle diffusion characteristic. The liquid crystal display panel 11 is composed of a small liquid crystal display panel having a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. For example, the image light from the liquid crystal display panel 11 is once transmitted toward the retroreflective member 2 by a polarization separation member 101 such as a reflective polarizing plate.

[0034] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2. By passing the video light through it twice to perform polarization conversion and convert a specific polarization wave into the other polarization wave, it is reflected by the polarization separation member 101, and a spatial floating image 3 which is a real image is displayed outside the transparent member 100. An absorption type polarizing plate 112 is provided on the outer light incident surface of the transparent member 100. This transparent member 100 is a transparent body only in the part where the video light passes through, and the other parts are composed of a light shielding member 100b that blocks light so that external light does not enter the set. Depending on the performance of the retroreflective member 2, the polarization axes of the video light after reflection may become uneven. In this case, a part of the video light with uneven polarization axes is reflected by the polarization separation member 101 and returns to the video display device 1. This light is reflected again on the video display surface of the liquid crystal display panel 11 that constitutes the video display device 1, generating a ghost image and significantly degrading the image quality of the spatial floating image 3. Therefore, in this embodiment, an absorption type polarizing plate 12 is further provided on the video display surface of the video display device 1. Or, by providing an antireflection film (not shown) on the video output side surface of the absorption type polarizing plate 12 provided on the surface of the video display device 1, the light of the ghost image is transmitted and absorbed by the absorption type polarizing plate 12, thereby preventing the image quality degradation caused by the ghost image of the spatial floating image 3.

[0035] Furthermore, in order to reduce the image quality degradation caused by sunlight or illumination light outside the housing 106 that houses the video display device 1 and other optical components, it is advisable to provide an absorption type polarizing plate 112 on the outer surface of the transparent member 100. Further, when external light enters the retroreflective member 2, a strong ghost image is generated. Therefore, the retroreflective member 2 is tilted (tilt angle θ), and it is arranged at a position away from the window portion 100a formed of a transparent body through which the retroreflected video light passes, so as to prevent the incidence of external light. Similarly, the video display device 1 is arranged at a position away from the window portion 100a, and when the video display device 1 is provided at a position where the video light emitted from the video display device 1 cannot be visually recognized from the window portion 100a, the generation of ghost images is reduced. (The window portion 100a is a form of an opening.)

[0036] Also, the polarization separation member 101 is formed of a reflective polarizing plate or a metal multilayer film that reflects a specific polarization wave.

[0037] The spatial floating image 3 emitted from the window portion 100a is reflected by the reflection mirror 400. At this time, by setting the angle of the reflection mirror 400 to a desired angle with respect to the plane of the window portion 100a, the position and angle of the obtained spatial floating image 3 can be changed. If a reflection mirror 400 having a characteristic of high reflectance for a specific polarization wave is used, it can be used as a mirror with high transmittance. Also, if an optical system that obtains spatial floating image light with an S polarization wave is used, a high reflectance can be obtained even by using a transparent body mirror without forming a reflective film. As a result, a good spatial floating image with high visibility (denoted as a stereoscopic image in Fig. 6B) can be obtained even by using a transparent body mirror, and it does not hinder the viewer from monitoring the outdoor scene. On the other hand, in the optical system excluding the reflection mirror 400, a planar image shown in the figure can be obtained by the image light transmitted through the window portion 100a as shown in Fig. 6B.

[0038] <Spatial floating image display system (4)> Fig. 6C is a diagram showing another example (fourth example) of the main configuration of a spatial floating image display device according to an embodiment of the present invention. In Fig. 6C, similar to Fig. 6B, the image display device 1 includes a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization wave having a narrow-angle diffusion characteristic. The liquid crystal display panel 11 is composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel 11 exceeding 80 inches. For example, an image light from the liquid crystal display panel 11 is once transmitted toward the retroreflective member 2 by a polarization separation member 101 such as a reflective polarizing plate, and the transmitted image light is reflected by the retroreflective member 2. Here, the polarization separation member 101 is also referred to as a beam splitter, and has a characteristic of transmitting image light accompanied by a specific polarization (P polarization or S polarization), and reflecting image light accompanied by a polarization different from the specific polarization (S polarization or P polarization).

[0039] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2. By passing the video light through it twice to perform polarization conversion and convert a specific polarization wave into the other polarization wave, it is reflected by the polarization separation member 101, and a spatial floating image 3, which is a real image, is displayed outside the transparent member 100. Similar to FIG. 6B, an absorption type polarizing plate 112 is provided on the outer light incident surface of the transparent member 100. Although not shown, similar to FIG. 6B, the periphery of the transparent member 100 may be surrounded by a light shielding member 100b so that external light does not enter the retroreflective member 2 or the video display device 1.

[0040] The arrangement of the main components of the spatial floating image display device will be described with reference to FIG. 6C. In FIG. 6C, when observing from the observation direction C indicated by the arrow, the two-dimensional planar spatial floating image 3 can be observed. The position where the spatial floating image 3 is formed is determined as follows. In FIG. 6C, the video display device 1 and the retroreflective member 2 are arranged to be parallel to each other. Specifically, the video display surface of the liquid crystal display panel 11 constituting the video display device 1 and the reflection surface of the retroreflective member 2 are arranged facing each other. Therefore, it is possible to observe a suitable spatial floating image 3. On the other hand, the video display surface of the liquid crystal display panel 11 constituting the video display device 1 and the reflection surface of the retroreflective member 2 may be arranged to be substantially parallel to each other. If the angle formed between them is around 10 degrees, the generated ghost image will not be a problem in practice, that is, even if a ghost image occurs, it will hardly affect the visibility of the spatial floating image 3.

[0041] Let the point B be the intersection point of the line segment A - A' connecting an arbitrary point A (here, a central point on the liquid crystal display panel 11) on the liquid crystal display panel 11 constituting the image display device 1 and the corresponding point A' (similarly, a central point on the retroreflective member 2) on the retroreflective member 2, and let the length of the line segment AB be L1. The line segment A - A' is the optical axis of the image light emitted from the image display surface of the liquid crystal display panel 11, the emission direction of the light source is substantially perpendicular to the image display surface of the liquid crystal display panel 11, or the line segment A - A' is substantially perpendicular or perpendicular to the image display surface of the liquid crystal display panel 11. Next, let the point C be a point at a length L2 in the vertical direction (the direction in which the transparent member 100 in FIG. 6C is arranged) from the point B on the polarization separation member 101. The length L1 of the line segment AB and the length L2 of the line segment BC are substantially the same length. Then, a spatial floating image 3 is formed on the two-dimensional plane centered on the point C.

[0042] Here, the description was made with respect to a central point A on the liquid crystal display panel 11, but for any point on the liquid crystal display panel 11, the relationship L1 = L2 holds as described above. Therefore, in FIG. 6C, if the liquid crystal display panel 11 is arranged farther away from the point B of the polarization separation member 101, L1 becomes longer, and from the relationship L1 = L2, L2 also becomes longer, so the position where the spatial floating image 3 is formed is higher. That is, the distance from the window portion 100a formed of the transparent member 100 to the spatial floating image 3 becomes longer. Thus, the display position of the spatial floating image 3 changes according to the distance between the liquid crystal display panel 11 and the polarization separation member 101. That is, the display position of the spatial floating image 3 is a position determined according to the distance between the liquid crystal display panel 11 and the polarization separation member 101.

[0043] However, when the liquid crystal display panel 11 emits video light of the same intensity, arranging the liquid crystal display panel 11 at a greater distance from the polarization separation member 101 also increases the distance between the liquid crystal display panel 11 and the retroreflective member 2. As a result, the intensity (luminance) of the video light reaching the retroreflective member 2 from the liquid crystal display panel 11 decreases, and consequently, the brightness of the floating video image 3 also decreases. Therefore, since there is a trade-off relationship between the distance from the floating video image 3 to be displayed to the transparent member 100 and the brightness of the floating video image 3, a suitable and highly visible floating video image 3 can be displayed by adjusting the arrangement positions of the liquid crystal display panel 11 and the polarization separation member 101.

[0044] Also, as is clear from FIG. 6C, when the angle formed by the polarization separation member 101 and the line segment A - A' (the optical axis of the video light emitted from the liquid crystal display panel 11) is 45 degrees, the size of the video generated by the video display device 1 and the floating video image 3 is the same. On the other hand, although not shown, when the above angle is greater than 45 degrees, the width of the floating video image 3 becomes smaller than the video generated by the video display device 1. Conversely, when the above angle is smaller than 45 degrees, the width of the floating video image 3 becomes larger than the video generated by the video display device 1.

[0045] <Spatial floating video display system (5)> FIG. 6D and FIG. 6E are diagrams showing another example (the fifth example) of the main configuration of the spatial floating video display device according to an embodiment of the present invention. The spatial floating video display device shown in FIG. 6D is composed of the same components as those in FIG. 6C, that is, a video display device 1, a retroreflective member 2, a λ / 4 plate 21, a polarization separation member 101, a transparent member 100, and the like. Further, the video display surface of the liquid crystal display panel 11 constituting the video display device 1 and the retroreflective surface of the retroreflective member 2 are arranged to face each other.

[0046] However, although in FIG. 6D the display surface of the liquid crystal display panel 11 that constitutes the video display device 1 and the reflecting surface of the retroreflective member 2 are arranged to face each other, they differ in that the retroreflective member 2 is located above the video display device 1. That is, the video display device 1 is arranged at a position away from the transparent member 100. Therefore, if the video display device 1 is provided at a position where the video light emitted from the video display device 1 cannot be visually recognized from the transparent member 100, the generation of ghost images is reduced. Further, the retroreflective member 2 is tilted and arranged at a position away from the transparent member 100 through which the retroreflected video light passes to prevent the incidence of external light. That is, the direction of the video light emitted from the liquid crystal display panel 11 that constitutes the video display device 1, in other words, the line segment A - A' connecting point A and point A' is horizontal in FIG. 6C, but in FIG. 6D, it is inclined upward to the left and differs in that the angle formed by the line segment A - A' and the polarization separation member 101 is greater than 45 degrees. As a result, it becomes possible to observe the tilted spatial floating image 3.

[0047] Furthermore, in FIG. 6D, while the spatial floating image 3 is formed horizontally as in FIG. 6C, it is formed with an inclination angle according to the inclination of the above-mentioned line segment A - A' and the inclination angle of the polarization separation member 101. That is, by changing the inclination of the line segment A - A' and the inclination angle of the polarization separation member 101, it is possible to adjust the angle of the plane on which the spatial floating image 3 is formed, and it becomes possible to set the user's viewing direction S at an appropriate angle.

[0048] In the spatial floating image display device shown in FIG. 6E, it is composed of the same components as in FIG. 6D, and the arrangement of the components is also the same, but the inclination of the polarization separation member 101 is larger (has an inclination angle closer to horizontal) compared to FIG. 6D. Therefore, the angle β formed by the optical axis of the video light, that is, the line segment A - A', and the polarization separation member 101 is smaller than the angle α in FIG. 6D. That is, the relationship is angle α > angle β.

[0049] From the above relationship (angle α > angle β), as shown in FIG. 6E, the observation direction S of the spatial floating image 3 is farther from the vertical direction compared to FIG. 6D. Further, the observed spatial floating image 3 is inclined more than in FIG. 6D.

[0050] As described above, by adjusting the direction of the image light, that is, the angle (α or β) formed by the line segment A - A' and the polarization separation member 101, the angle formed by the spatial floating image 3 and the transparent member 100 can be changed. Therefore, it is possible to obtain a suitable observation direction for the user.

[0051] <Reflective polarizing plate> For the reflective polarizing plate with the grid structure of the present invention, the characteristics for light from the direction perpendicular to the polarization axis deteriorate. For this reason, specifications along the polarization axis are desirable, and the light source of this embodiment that can emit the outgoing image light from the liquid crystal display panel 11 at a narrow angle is an ideal light source. Also, regarding the characteristics in the horizontal direction, there is a deterioration in characteristics for light from an oblique direction as well. Considering the above characteristics, hereinafter, a configuration example of this embodiment will be described in which a light source that can emit the outgoing image light from the liquid crystal display panel 11 at a narrower angle is used as the backlight of the liquid crystal display panel 11. Thereby, a spatial floating image 3 with high contrast can be provided.

[0052] <Image display device> Next, the image display device 1 of this embodiment will be described with reference to the drawings. The image display device 1 of this embodiment includes a light source device 13 that constitutes its light source together with an image display element (liquid crystal display panel 11). In FIG. 7, the light source device 13 is shown as a developed perspective view together with the liquid crystal display panel.

[0053] As shown by arrow 30 in Fig. 7, this liquid crystal display panel (image display element) obtains an illumination light beam with narrow-angle diffusion characteristics, that is, characteristics similar to a laser beam with strong directivity (linear propagation) and the polarization planes aligned in one direction, from the light source device 13 which is a backlight device. The image light modulated according to the input video signal is reflected by the retroreflective member 2, transmitted through the windshield 105, and forms a spatially floating image which is a real image (see Fig. 1). Also, in Fig. 7, the liquid crystal display panel 11 constituting the image display device 1, further, the optical direction conversion panel 54 that controls the directivity characteristics of the emitted light beam from the light source device 13, and, if necessary, a narrow-angle diffusion plate (not shown) are provided. That is, polarizing plates are provided on both surfaces of the liquid crystal display panel 11, and the image light of a specific polarization modulates the light intensity according to the video signal and is emitted (see arrow 30 in Fig. 7). Thereby, a desired image is projected as light of a specific polarization with high directivity (linear propagation) through the optical direction conversion panel 54 toward the retroreflective member 2. After being reflected by the retroreflective member 2, it is transmitted toward the eyes of viewers outside the store (space) to form the spatially floating image 3. Note that a protective cover 50 (see Figs. 8 and 9) may be provided on the surface of the above-described optical direction conversion panel 54.

[0054] In this embodiment, in order to improve the utilization efficiency of the emitted light beam (indicated by arrow 30) from the light source device 13 and significantly reduce the power consumption, in the video display device 1 including the light source device 13 and the liquid crystal display panel 11, the light (see arrow 30 in FIG. 8) from the light source device 13 is projected toward the retroreflective member 2, and after being reflected by the retroreflective member 2, the spatial floating image 3 is formed at a desired position by a transparent sheet (not shown) provided on the surface of the windshield 105. Specifically, this transparent sheet controls the imaging position of the floating image while imparting high directivity by optical components such as a Fresnel lens or a linear Fresnel lens. According to this, the video light from the video display device 1 can efficiently reach an observer outside the windshield 105 (for example, on the sidewalk) with high directivity (straightness) like a laser beam. As a result, a high-quality floating image can be displayed with high resolution, and at the same time, it is possible to significantly reduce the power consumption of the video display device 1 including the LED (Light Emitting Diode) element 201 of the light source device 13.

[0055] <Example of video display device (1)> FIG. 7 is a diagram showing another example of the video display device 1. FIG. 8 shows a state in which the liquid crystal display panel 11 and the light direction conversion panel 54 are arranged on the light source device 13 of FIG. 7. This light source device 13 is formed of, for example, plastic, and houses the LED element 201 and the light guide 203 inside. At the end face of the light guide 203, in order to convert the divergent light from each LED element 201 into a substantially parallel light beam as shown in FIG. 8 and the like, it has a shape in which the cross-sectional area gradually increases toward the light receiving part, and has a lens shape that has an effect of gradually reducing the divergence angle by total reflection a plurality of times when propagating inside. The liquid crystal display panel 11 constituting the video display device 1 is attached to the upper surface thereof. Further, on one side surface (the left end surface in this example) of the case of the light source device 13, the LED element 201 which is a semiconductor light source and the LED substrate 202 (see FIG. 8) on which its control circuit is mounted are attached, and on the outer surface of the LED substrate 202, a heat sink which is a member for cooling the heat generated by the LED element 201 and the control circuit may be attached.

[0056] Also, on the frame (not shown) of the liquid crystal display panel 11 attached to the upper surface of the case of the light source device 13, the liquid crystal display panel 11 attached to the frame, and further, an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11, etc. are attached and configured. That is, the liquid crystal display panel 11, which is an image display element, together with the LED element 201, which is a solid light source, generates a display image by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes an electronic device. At this time, since the generated image light has a narrow diffusion angle and only a specific polarization component, a novel image display device 1, which is close to a surface-emitting laser image source driven by an image signal, can be obtained. At present, it is technically and safety-wise impossible to obtain a laser light beam of the same size as the image obtained by the above-described image display device 1 using a laser device. Therefore, in this embodiment, for example, light close to the above-described surface-emitting laser image light is obtained from the light beam from a general light source equipped with the LED element 201.

[0057] Next, the configuration of the optical system housed in the case of the light source device 13 will be described in detail with reference to FIG. 9 together with FIG. 8. Since FIGS. 8 and 9 are cross-sectional views, only one of the plurality of LED elements 201 constituting the light source is shown, and these are converted into substantially 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 and the LED element 201 are attached while maintaining a predetermined positional relationship. Note that each of these light guides 203 is formed of a light-transmissive resin such as acrylic. And the LED light-receiving surface at the end of this light guide has, for example, an outer peripheral surface of a conical convex shape obtained by rotating a parabolic cross-section. At the top, it has a concave portion formed with a convex portion (that is, a convex lens surface) at the central portion thereof, and at the central portion of the flat portion, it has a convex lens surface protruding outward (or a concave lens surface recessed inward may also be used) (not shown). Note that the outer shape of the light-receiving portion of the light guide 203 has a parabolic shape forming a conical outer peripheral surface, and is set within an angle range that enables total reflection of the light emitted from the LED element 201 in the peripheral direction inside it, or a reflecting surface is formed.

[0058] On the other hand, the LED elements 201 are respectively arranged at predetermined positions on the surface of the LED substrate 202 which is its circuit board. This LED substrate 202 is arranged and fixed with respect to the LED collimator (light-receiving end face 203a) such that the LED elements 201 on its surface are respectively positioned at the central portions of the aforementioned concave portions.

[0059] According to such a configuration, due to the shape of the light-receiving end face 203a of the light guide 203, the light emitted from the LED element 201 can be taken out as substantially parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0060] As described above, the light source device 13 is configured by attaching a light source unit in which a plurality of LED elements 201 as light sources are arranged on a light receiving end face 203a, which is a light receiving part provided on the end face of the light guide 203. The divergent light beam from the LED element 201 is made into substantially parallel light by the lens shape of the light receiving end face 203a of the light guide end face, and is guided through the inside of the light guide 203 (in a direction parallel to the drawing), as indicated by the arrow, and is emitted by the light beam direction conversion means 204 toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front from the drawing). By optimizing the distribution (density) of the light beam direction conversion means 204 according to the shape of the inside or the surface of the light guide 203, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled. The above-described light beam direction conversion means 204 provides, for example, portions with different refractive indices on the surface shape of the light guide 203 or inside the light guide 203, so that the light beam propagating through the light guide 203 is emitted toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front from the drawing). At this time, when comparing the relative luminance ratio when comparing the luminance of the center of the screen and the peripheral portion of the screen in a state where the liquid crystal display panel 11 is directly facing the center of the screen and the viewpoint is placed at the same position as the diagonal dimension of the screen, if the relative luminance ratio is 20% or more, there is no practical problem, and if it exceeds 30%, the characteristics are even more excellent.

[0061] Note that FIG. 8 is a cross-sectional layout view for explaining the configuration and operation of the light source of this embodiment for polarization conversion in the light source device 13 including the above-described light guide 203 and LED element 201. In FIG. 8, the light source device 13 is composed of, for example, a light guide 203 provided with a light beam direction conversion means 204 on its surface or inside formed of plastic or the like, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 216, a lenticular lens, etc. On its upper surface, a liquid crystal display panel 11 provided with polarizing plates on the light source light incident surface and the video light emitting surface is attached.

[0062] A film or sheet-shaped reflective polarizing plate 49 is provided on the light source light incident surface (the lower surface in the figure) of the liquid crystal display panel 11 facing the light source device 13. Among the natural light beams 210 emitted from the LED element 201, one-sided polarized wave (for example, P wave) 212 is selectively reflected, reflected by the reflection sheet 205 provided on one surface (the lower side in the figure) of the light guide 203, and then directed back toward the liquid crystal display panel 11. Therefore, a retardation plate 216 (λ / 4 plate) is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49. The light beam is reflected by the reflection sheet 205 and passed through twice to convert the reflected light beam from P polarization to S polarization, thereby improving the utilization efficiency of the light source light as video light. The video light beam whose light intensity is modulated by the video signal in the liquid crystal display panel 11 (arrow 213 in FIG. 8) enters the retroreflective member 2, and as shown in FIG. 1, after reflection, it passes through the windshield 105 to obtain a spatial floating image 3, which is a real image, inside or outside the store (space).

[0063] FIG. 9 is a cross-sectional layout diagram for explaining the configuration and operation of the light source of this embodiment for polarization conversion in the light source device 13 including the light guide 203 and the LED element 201, similar to FIG. 8. Similarly, the light source device 13 is composed of a light guide 203 provided with a light beam direction conversion means 204 on its surface or inside formed of, for example, plastic, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 216, a lenticular lens, etc. A liquid crystal display panel 11 having polarizing plates on the light source light incident surface and the video light exit surface is attached as a video display element on its upper surface.

[0064] Also, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and one-sided polarization (for example, S wave) 211 of the natural light beam 210 emitted from the LED element 201 is selectively reflected, reflected by the reflection sheet 205 provided on one surface (the lower side in the figure) of the light guide 203, and then directed back toward the liquid crystal display panel 11. A retardation plate 216 (λ / 4 plate) is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the light is reflected by the reflection sheet 205 and passed through twice to convert the reflected light beam from S polarization to P polarization, thereby improving the utilization efficiency of the light source light as video light. The video light beam whose light intensity is modulated by the video signal in the liquid crystal display panel 11 (arrow 214 in FIG. 9) enters the retroreflective member 2 and, as shown in FIG. 1, after reflection, passes through the windshield 105 to obtain a spatial floating image 3 that is a real image inside or outside the store (space).

[0065] In the light source device 13 shown in FIGS. 8 and 9, together with the action of the reflective polarizing plate 49 provided on the light incident surface of the opposing liquid crystal display panel 11, since one-sided polarization components are reflected by the reflective polarizing plate 49, the theoretically obtainable contrast ratio is the reciprocal of the cross transmittance of the reflective polarizing plate 49 multiplied by the reciprocal of the cross transmittance obtained by the two polarizing plates attached to the liquid crystal display panel 11. As a result, high contrast performance can be obtained. In fact, it was experimentally confirmed that the contrast performance of the displayed image was improved by a factor of 10 or more. As a result, a high-quality video comparable to that of self-emitting organic EL was obtained.

[0066] <Example of Video Display Device (2)> FIG. 10 shows another example of the specific configuration of the video display device 1. The light source device 13 in FIG. 10 is the same as the light source device in FIGS. 12 and the like. This light source device 13 is configured by housing an LED, a collimator, a synthetic diffusion block, a light guide, etc. in a case made of, for example, plastic, and a liquid crystal display panel 11 is attached to the upper surface thereof. Also, on one side surface of the case of the light source device 13, LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources shown in FIGS. 12 and the like, and an LED substrate 102 on which the control circuit thereof is mounted are attached, and on the outer surface of the LED substrate 102, a heat sink 103 (see FIG. 10), which is a member for cooling the heat generated by the LED elements 14a and 14b and the control circuit, is attached (see also FIGS. 12 and 13).

[0067] Further, on the liquid crystal display panel frame attached to the upper surface of the case, the liquid crystal display panel 11 attached to the frame, and further, an FPC (Flexible Printed Circuits) 403 (see FIG. 10) electrically connected to the liquid crystal display panel 11, etc. are attached and configured. That is, the liquid crystal display panel 11, which is a video display element, together with the LED elements 14a and 14b, which are solid light sources, generates a display video by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown here) that constitutes the electronic device.

[0068] <Example of Video Display Device (3)> Next, another example (Example 3 of the display device) of the specific configuration of the video display device 1 will be described with reference to FIG. 11. The light source device of this video display device 1 converts a divergent light beam of light (a mixture of P-polarized light and S-polarized light) from an LED into a substantially parallel light beam by a collimator (collimator lens or LED collimator lens) 18 and reflects it toward the liquid crystal display panel 11 by the reflecting surface of the reflective light guide 304. The reflected light enters the reflective polarizing plate 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. In the reflective polarizing plate 49, a specific polarization (for example, P-polarized light) passes through and enters the liquid crystal display panel 11. The other polarization (for example, S-polarized light) is reflected by the reflective polarizing plate and heads back toward the reflective light guide 304 again. The reflective polarizing plate 49 is installed with an inclination so as not to be perpendicular to the principal ray of the light from the reflecting surface of the reflective light guide 304, and the principal ray of the light reflected by the reflective polarizing plate 49 enters the transmissive surface of the reflective light guide 304. The light that has entered the transmissive surface of the reflective light guide 304 passes through the back surface of the reflective light guide 304, passes through the λ / 4 plate 270 which is a retardation plate, and is reflected by the reflector 271. The light reflected by the reflector 271 passes through the λ / 4 plate 270 again and passes through the transmissive surface of the reflective light guide 304. The light that has passed through the transmissive surface of the reflective light guide 304 enters the reflective polarizing plate 49 again. At this time, since the light that enters the reflective polarizing plate 49 again has passed through the λ / 4 plate 270 twice, the polarization is converted into the polarization (for example, P-polarized light) that passes through the reflective polarizing plate 49. Therefore, the light whose polarization has been converted passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Regarding the polarization design related to polarization conversion, the polarization can be configured in the reverse (reversing S-polarized light and P-polarized light) from the above description.

[0069] As a result, the light from the LED is aligned to a specific polarization (e.g., P-polarization), enters the liquid crystal display panel 11, is luminance-modulated according to the video signal, and a video is displayed on the panel surface. As in the above example, a plurality of LEDs constituting the light source are shown (however, only one is shown in FIG. 16 due to the cross-sectional view), and these are attached to the collimator 18 at predetermined positions. The collimator 18 is formed of, for example, a light-transmissive resin such as acrylic or glass. And this collimator 18 may have an outer peripheral surface of a conical convex shape obtained by rotating a parabolic cross-section. At its top, it may have a concave portion with a convex portion (i.e., a convex lens surface) formed at its central portion. Also, at the central portion of its flat surface portion, it has a convex lens surface protruding outward (or a concave lens surface recessed inward may also be acceptable). The parabolic surface forming the conical outer peripheral surface of the collimator 18 is set within a range of angles that can totally reflect the light emitted from the LED in the peripheral direction inside it, or a reflecting surface is formed.

[0070] Note that the LEDs are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the collimator 18 such that the LEDs on its surface are respectively located at the central portion of the top of the conical convex shape (the concave portion if there is a concave portion at the top).

[0071] According to such a configuration, by the collimator 18, among the light radiated from the LED, particularly the light radiated from its central portion, is condensed by the convex lens surface forming the outer shape of the collimator 18 and becomes parallel light. Also, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface of the collimator 18 and is similarly condensed to become parallel light. In other words, according to the collimator 18 having a convex lens formed at its central portion and a parabolic surface formed at its peripheral portion, almost all of the light generated by the LED can be taken out as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0072] The above configuration is the same as that of the light source device of the video display device shown in FIGS. 12, 13, etc. Further, the light converted into substantially parallel light by the collimator 18 shown in FIG. 11 is reflected by the reflective light guide 304. Among the light, the light of a specific polarization state passes through the reflective polarizing plate 49 due to the action of the reflective polarizing plate 49, and the light of the other polarization state reflected by the action of the reflective polarizing plate 49 passes through the light guide 304 again. The light is reflected by a reflector 271 located at a position opposite to the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarization-converted by passing through the λ / 4 plate 270, which is a retardation plate, twice. The light reflected by the reflector 271 passes through the light guide 304 again and enters the reflective polarizing plate 49 provided on the opposite surface. Since the incident light has been polarization-converted, it passes through the reflective polarizing plate 49 and is incident on the liquid crystal display panel 11 with the polarization directions aligned. As a result, all the light from the light source can be utilized, so the geometric optical utilization efficiency of the light is doubled. Also, since the polarization degree (extinction ratio) of the reflective polarizing plate is also multiplied by the extinction ratio of the entire system, the contrast ratio of the entire display device is significantly improved by using the light source device of this embodiment. By adjusting the surface roughness of the reflection surface of the reflective light guide 304 and the surface roughness of the reflector 271, the light reflection diffusion angle at each reflection surface can be adjusted. For each design, the surface roughness of the reflection surface of the reflective light guide 304 and the surface roughness of the reflector 271 may be adjusted so that the uniformity of the light incident on the liquid crystal display panel 11 becomes more suitable.

[0073] Note that the λ / 4 plate 270, which is the retardation plate in FIG. 11, does not necessarily need to have a retardation of λ / 4 with respect to the polarization incident perpendicularly to the λ / 4 plate 270. In the configuration of FIG. 11, any retardation plate that changes the phase by 90° (λ / 2) when the polarization passes through it twice is acceptable. The thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarization.

[0074] The light emitted from the liquid crystal display panel 11 has the same diffusion characteristics in both the horizontal direction of the screen (displayed on the X-axis in FIG. 16(A)) and the vertical direction of the screen (displayed on the Y-axis in FIG. 16(B)) in a conventional TV set. In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel 11 of this embodiment are such that, for example, as shown in Example 1 of FIG. 16, the viewing angle at which the luminance becomes 50% of the front view (angle 0 degrees) is 13 degrees, which is 1 / 5 of the conventional 62 degrees. Similarly, for the viewing angle in the vertical direction, the reflection angle of the reflective light guide and the area of the reflection surface are optimized so that the upper viewing angle is suppressed to about 1 / 3 of the lower viewing angle with the upper and lower viewing angles being uneven. As a result, the amount of video light directed toward the monitoring direction is significantly improved compared to a conventional liquid crystal TV, and the luminance becomes 50 times or more.

[0075] Furthermore, if the viewing angle characteristics shown in Example 2 of FIG. 16 are adopted, the viewing angle at which the luminance becomes 50% of the front view (angle 0 degrees) is 5 degrees, which is 1 / 12 of the conventional 62 degrees. Similarly, for the viewing angle in the vertical direction, the reflection angle of the reflective light guide and the area of the reflection surface are optimized so that the viewing angle is suppressed to about 1 / 12 of the conventional value with the upper and lower viewing angles being equal. As a result, the amount of video light directed toward the monitoring direction is significantly improved compared to a conventional liquid crystal TV, and the luminance becomes 100 times or more. As described above, by narrowing the viewing angle, the amount of light beam directed toward the monitoring direction can be concentrated, so the light utilization efficiency is significantly improved. As a result, even when using a liquid crystal display panel for a conventional TV, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant increase in luminance with the same power consumption, and it is possible to make the video display device 1 corresponding to the spatial floating video display system facing the outside.

[0076] Returning to FIG. 11. As a basic configuration, as shown in FIG. 11, a light beam with a narrow-angle directivity characteristic is incident on the liquid crystal display panel 11 by a light source device, and the luminance is modulated according to the video signal, so that the video information displayed on the screen of the liquid crystal display panel 11 is reflected by the retroreflective member 2 to obtain the spatial floating video 3, which is displayed outside or inside through the window glass 105.

[0077] <Example (1) of the light source device 13> Next, the configuration of the optical system such as the light source device housed in the housing 106 (see FIG. 6B) will be described in detail with reference to FIGS. 13(A) and (B) together with FIG. 12.

[0078] FIG. 12 shows the LED elements 14a and 14b that constitute the light source, and these are attached to the LED collimator 15 at predetermined positions. Note that each of these LED collimators 15 is formed of a light-transmitting resin such as acrylic, for example. And as shown in FIG. 13(B) as well, this LED collimator 15 has an outer peripheral surface 156 having a conical convex shape obtained by rotating a parabolic cross section, and at its top, it has a concave portion 153 formed with a convex portion (that is, a convex lens surface) 157 at its central portion. Also, at the central portion of its flat portion, it has a convex lens surface (alternatively, it may be a concave lens surface recessed inward) 154 that protrudes outward. Note that the parabolic surface forming the conical outer peripheral surface 156 of the LED collimator 15 is set within a range of an angle that enables total reflection of the light emitted from the LED elements 14a and 14b in the peripheral direction inside it, or a reflecting surface is formed.

[0079] Also, the LED elements 14a and 14b are respectively arranged at predetermined positions on the surface of the LED substrate 102 which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the LED collimator 15 such that the LED elements 14a or 14b on its surface are respectively positioned at the central portions of the concave portions 153.

[0080] According to such a configuration, among the light emitted from the LED element 14a or 14b by the above-described LED collimator 15, in particular, the light radiated upward (rightward in FIG. 13(B)) from the central portion thereof is condensed by the two convex lens surfaces 157 and 154 forming the outer shape of the LED collimator 15 to become parallel light. Further, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface 156 of the LED collimator 15, and similarly, is condensed to become parallel light. In other words, according to the LED collimator 15 having a convex lens formed in the central portion thereof and a parabolic surface formed in the peripheral portion thereof, almost all of the light generated by the LED element 14a or 14b can be taken out as parallel light, and the utilization efficiency of the generated light can be improved.

[0081] As shown in FIG. 13, a polarization conversion element 21 is provided on the light emission side of the LED collimator 15. As is clear from FIG. 13, this polarization conversion element 21 combines a columnar light-transmissive member (hereinafter, a parallelogram column) having a parallelogram cross section and a columnar light-transmissive member (hereinafter, a triangular column) having a triangular cross section, and is configured to be arranged in an array of a plurality of members parallel to a plane orthogonal to the optical axis of the parallel light from the LED collimator 15. Further, a polarization beam splitter (hereinafter, abbreviated as "PBS film") 211 and a reflection film 212 are alternately provided at the interfaces between the adjacent light-transmissive members arranged in this array, and a λ / 2 phase plate 215 is provided on the emission surface from which the light incident on the polarization conversion element 21 and transmitted through the PBS film 211 is emitted.

[0082] A rectangular composite diffusion block 16 shown in FIG. 13(A) is further provided on the emission surface of this polarization conversion element 21. That is, the light emitted from the LED element 14a or 14b becomes parallel light by the action of the LED collimator 15, enters the composite diffusion block 16, is diffused by the texture 161 on the emission side, and then reaches the light guide 17.

[0083] The light guide 17 is a member formed of a light-transmissive resin such as acrylic into a rod shape with a substantially triangular cross-section (see Fig. 13(B)). As is also clear from Fig. 12, the light guide light incident portion (surface) 171 that faces the light exit surface of the synthetic diffusion block 16 via the first diffusion plate 18a, the light guide light reflecting portion (surface) 172 that forms an inclined surface, and the light guide light exit portion (surface) 173 that faces the liquid crystal display panel 11, which is an image display element, via the second diffusion plate 18b.

[0084] As shown in Fig. 13(B), which is a partial enlarged view of the light guide light reflecting portion (surface) 172 of this light guide 17, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a serrated shape. The reflecting surface 172a (the line segment rising to the upper right in the figure) forms an angle αn (n is a natural number, and in this example, for example, it is 1 to 130) with the horizontal plane indicated by the dashed-dotted line in the figure. As an example, here, αn is set to 43 degrees or less (however, 0 degrees or more).

[0085] The light guide incident portion (surface) 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the light exit surface of the synthetic diffusion block 16 is diffused and incident via the first diffusion plate 18a, and as is also clear from Fig. 12, it reaches the light guide light reflecting portion (surface) 172 while being slightly bent (deflected) upward by the light guide incident portion (surface) 171, and is reflected here and reaches the liquid crystal display panel 11 provided on the upper light exit surface of Fig. 12.

[0086] According to the image display device 1 described in detail above, it is possible to further improve the light utilization efficiency and its uniform illumination characteristics, and at the same time, it is possible to manufacture it in a small size and at low cost, including the modularized S-polarized light source device. In the above description, the polarization conversion element 21 is described as being attached after the LED collimator 15, but the present invention is not limited thereto, and the same effects can also be obtained by providing it in the optical path reaching the liquid crystal display panel 11.

[0087] Note that in the light guide light reflection part (surface) 172, a large number of reflection surfaces 172a and connection surfaces 172b are alternately formed in a sawtooth shape. The illumination light beam is totally reflected on each reflection surface 172a and goes upward. Furthermore, a narrow-angle diffuser plate (not shown) is provided on the light guide light exit part (surface) 173, and the light beam is incident on the light direction conversion panel 54 that controls the directivity as a substantially parallel diffused light beam, and is incident on the liquid crystal display panel 11 from an oblique direction. In this embodiment, the light direction conversion panel 54 is provided between the light guide exit surface 173 and the liquid crystal display panel 11, but the same effect can be obtained even if it is provided on the exit surface of the liquid crystal display panel 11.

[0088] <Example of the light source device 13 (2)> Another example of the configuration of the optical system such as the light source device 13 is shown in FIG. 14. Similar to the example shown in FIG. 13, a plurality (two in this example) of LED elements 14a and 14b constituting the light source are shown, and these are attached to the LED collimator 15 at predetermined positions. Note that each of these LED collimators 15 is formed of a light-transmissive resin such as acrylic. And, similar to the example shown in FIG. 13, this LED collimator 15 has an outer peripheral surface 156 having a conical convex shape obtained by rotating a parabolic cross-section, and at its top, it has a concave portion 153 formed with a convex portion (that is, a convex lens surface) 157 at its central portion. Also, at the central portion of its flat portion, it has a convex lens surface (or it may be a concave lens surface recessed inward) 154 protruding outward. Note that the parabolic surface forming the conical outer peripheral surface 156 of the LED collimator 15 is set within a range of an angle that can totally reflect the light emitted from the LED element 14a in the peripheral direction inside it, or a reflecting surface is formed.

[0089] Also, the LED elements 14a and 14b are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the LED collimator 15 such that the LED elements 14a or 14b on its surface are respectively located at the central portions of the concave portions 153.

[0090] According to such a configuration, among the light emitted from the LED elements 14a or 14b by the above-described LED collimator 15, in particular, the light radiated upward (rightward in the figure) from the central portion thereof is condensed by the two convex lens surfaces 157 and 154 forming the outer shape of the LED collimator 15 and becomes parallel light. Also, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface 156 of the LED collimator 15 and, similarly, is condensed and becomes parallel light. In other words, according to the LED collimator 15 having a convex lens formed in its central portion and a parabolic surface formed in its peripheral portion, almost all of the light generated by the LED elements 14a or 14b can be taken out as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0091] Note that a light guide 170 is provided on the light emission side of the LED collimator 15 via a first diffusion plate 18a. The light guide 170 is a member formed in a rod shape with a substantially triangular cross section (see FIG. 14(A)) by a light-transmissive resin such as acrylic, and as is clear from FIG. 14(A), an incident portion (surface) 171 of the light guide 170 facing the emission surface of the synthetic diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (surface) 172 forming an inclined surface, and a light guide light emission portion (surface) 173 facing the liquid crystal display panel 11, which is an image display element, via a reflective polarizing plate 200.

[0092] If an object having a characteristic of reflecting P-polarized light (transmitting S-polarized light) is selected for this reflective polarizing plate 200, for example, P-polarized light among the natural light emitted from the LED elements 14a and 14b, which are light sources, is reflected, passes through the λ / 4 plate 172c provided on the light guide light reflection portion 172 shown in FIG. 14(B), is reflected by the reflection surface 172d, and is converted into S-polarized light by passing through the λ / 4 plate 172c again, so that all the light fluxes incident on the liquid crystal display panel 11 are unified into S-polarized light.

[0093] Similarly, if an object having the property of reflecting S-polarized light (transmitting P-polarized light) is selected as the reflective polarizing plate 200, the S-polarized light among the natural light emitted from the LED elements 14a and 14b as the light source is reflected, passes through the λ / 4 plate 172c provided on the light guide light reflecting portion 172 shown in FIG. 14(B), is reflected by the reflecting surface 172d, and is converted into P-polarized light by passing through the λ / 4 plate 172c again. All the light beams incident on the liquid crystal display panel 52 are unified into P-polarized light. Polarization conversion can also be realized with the configuration described above.

[0094] <Example of the light source device 13 (3)> Another example of the configuration of the optical system of the light source device and the like will be described with reference to FIG. 11. In the third example, as shown in FIG. 11, the divergent light beam of natural light (a mixture of P-polarized light and S-polarized light) from the LED substrate 102 is converted into a substantially parallel light beam by the LED collimator lens 18 and reflected toward the liquid crystal display panel 11 by the reflective light guide 304. The reflected light is incident on the reflective polarizing plate 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304. A specific polarization wave (for example, S-polarization wave) is reflected by the reflective polarizing plate 49, passes through the surface connecting the reflective surfaces of the light guide 304, is reflected by the reflector 271 disposed facing the opposite surface of the light guide 304, and is polarization-converted by passing through the phase plate (λ / 4 wavelength plate) 270 twice. Then, it passes through the light guide and the reflective polarizing plate and is incident on the liquid crystal display panel 11 and modulated into image light. At this time, by aligning the specific polarization wave and the polarization plane after polarization conversion, the utilization efficiency of light becomes twice that of normal, and the polarization degree (extinction ratio) of the reflective polarizing plate is also multiplied by the extinction ratio of the entire system. Therefore, by using the light source device of this embodiment, the contrast ratio of the information display system is significantly improved.

[0095] As a result, the natural light from the LED can be aligned to a specific polarization (e.g., P polarization). Similar to the above example, a plurality of LEDs constituting the light source are provided (however, only one is shown in FIG. 12 for the longitudinal section), and these are attached to predetermined positions with respect to the LED collimator lens 18. Note that each of these LED collimator lenses 18 is formed of a light-transmissive resin or glass such as acrylic. And this LED collimator lens 18 has an outer peripheral surface having a conical convex shape obtained by rotating a parabolic cross section, and at its top, it has a concave portion formed with a convex portion (i.e., a convex lens surface) at its central portion. Also, at the central portion of its flat portion, it has a convex lens surface protruding outward (or it may be a concave lens surface recessed inward). Note that the parabolic surface forming the conical outer peripheral surface of the LED collimator lens 18 is set within an angular range that enables total internal reflection of the light emitted from the LED collimator lens 18 in the peripheral direction inside it, or a reflecting surface is formed.

[0096] Also, the LEDs are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the LED collimator lens 18 such that the LEDs on its surface are respectively positioned at the central portions of the concave portions.

[0097] According to such a configuration, among the light emitted from the LED by the LED collimator lens 18, in particular, the light emitted from the central portion thereof is condensed by the two convex lens surfaces forming the outer shape of the LED collimator lens 18 to become parallel light. Also, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface of the LED collimator lens 18 and similarly condensed to become parallel light. In other words, according to the LED collimator lens 18 having a convex lens formed at its central portion and a parabolic surface formed at its peripheral portion, almost all of the light generated by the LED can be taken out as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0098] <Example of video display device (4)>Furthermore, another example (Example 4 of the display device) of the configuration of the optical system such as the light source device of the display device will be described with reference to FIG. 17. This is a configuration example in the case where a diffusion sheet is used instead of the reflective light guide 304 in the light source device of Example 3 of the display device. Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) for converting the diffusion characteristics in the vertical and horizontal directions (not shown in the front-rear direction of the drawing) of the drawing are used on the light-emitting side of the light from the LED collimator lens 18, and the light from the LED collimator lens 18 is made to enter between the two optical sheets (diffusion sheets). These optical sheets may be a single sheet instead of two sheets. In the case of a single-sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes of the front and back surfaces of the single optical sheet. Also, a plurality of diffusion sheets may be used to share the function. Here, in the example of FIG. 17, regarding the reflection and diffusion characteristics due to the front surface shape and back surface shape of the optical sheet 207A and the optical sheet 207B, it is advisable to optimally design the number of LEDs, the divergence angle from the LED substrate (optical element) 102, and the optical specifications of the LED collimator lens 18 as design parameters so that the surface density of the light beam emitted from the liquid crystal display panel 11 becomes uniform. That is, the diffusion characteristics are adjusted by the surface shapes of a plurality of diffusion sheets instead of the light guide. In the example of FIG. 17, the polarization conversion is performed in the same manner as in Example 3 of the display device described above. That is, in the example of FIG. 17, the reflective polarizing plate 49 may be configured to have the characteristic of reflecting S-polarized light (transmitting P-polarized light). In that case, among the light emitted from the LED which is the light source, the P-polarized light is transmitted and the transmitted light enters the liquid crystal display panel 11. Among the light emitted from the LED which is the light source, the S-polarized light is reflected, and the reflected light passes through the retardation plate 270 shown in FIG. 17. The light that has passed through the retardation plate 270 is reflected by the reflector 271. The light reflected by the reflector 271 is converted into P-polarized light by passing through the retardation plate 270 again. The polarization-converted light passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that the λ / 4 plate 270 which is the retardation plate in FIG. 17 does not necessarily need to have a retardation of λ / 4 with respect to the polarization incident perpendicularly to the λ / 4 plate 270. In the configuration of FIG. 17, any retardation plate may be used as long as the phase changes by 90° (λ / 2) when the polarization passes through it twice. The thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarization.Note that in Fig. 17, regarding the polarization design related to polarization conversion, the polarization may be configured in the reverse manner (reversing S polarization and P polarization) from the above description.

[0099] <Example of the light source device 13 (5)> Another example of the configuration of the optical system of the light source device 13 will be described with reference to Fig. 18. As shown in Fig. 18(C), a polarization conversion element 21 is arranged on the light emitting side of the LED collimator lens 18. Then, the natural light from the LED element 14c is incident on an optical element 81 that aligns the polarization to a specific polarization and controls the diffusion characteristics, and by controlling the diffusion characteristics in the vertical and horizontal directions of the drawing (not shown in the front-back direction of the figure), the light distribution characteristics toward the reflecting surface of the reflective light guide 220 are optimized. As shown in Fig. 18(B), an uneven pattern 222 is provided on the surface of the reflective light guide 220, and the light is reflected toward a video display device (not shown) arranged on the opposite surface of the reflective light guide 220 to obtain desired diffusion characteristics. Since the arrangement accuracy of the LED element 14c and the LED collimator lens 18 of the light source greatly affects the efficiency of the light source, usually an optical axis accuracy of about 50 μm is required. Therefore, as a countermeasure against the decrease in the mounting accuracy due to the expansion of the LED collimator lens 18 caused by the heat generation of the LED, the inventors used a plurality or a single unit of the light source unit 223 structure in which several LED elements 14c and the LED collimator lens 18 are integrated in the light source device to reduce the decrease in the mounting accuracy.

[0100] In the embodiment shown in FIGS. 18(A), (B), and (C), a plurality of light source units 223 in which the LED element 14c and the LED collimator lens 18 are integrated are incorporated at both ends in the long side direction of the reflective light guide 220 (three on each side in the embodiment of FIG. 18), realizing luminance uniformity of the light source device. A plurality of uneven patterns 222 substantially parallel to the light source unit are formed on the reflecting surface 220a of the reflective light guide 220, and even in one uneven pattern 222, the amount of light incident on the image display device 1 can be accurately controlled by forming its surface into a polyhedron. In this embodiment, the shape of the reflecting surface is described as the uneven pattern 222, but it goes without saying that the present invention is not contravened if the light distribution pattern from the reflective light guide 220 toward the image display device 1 is controlled by the surface shape even with a pattern in which triangular surfaces, corrugated surfaces, etc. are arranged regularly or irregularly. Further, a light shielding wall 224 is provided on the side surface of the reflective light guide 220 so that the light controlled by the LED collimator lens 18 does not leak outside from the light source device 13, and the LED element 14c is preferably designed to enhance heat dissipation by a metal base 225.

[0101] <Lenticular sheet> The operation of a lenticular lens for controlling the diffusion characteristics of the light emitted from the image display device 1 will be described below. By optimizing the lens shape of the lenticular lens, it becomes possible to efficiently obtain the spatially floating image 3 by transmitting or reflecting the light emitted from the above-described image display device 1 through the windshield 105. That is, for the image light from the image display device 1, two lenticular lenses are combined, or a sheet for controlling the diffusion characteristics by arranging a microlens array in a matrix is provided, and in the X-axis and Y-axis directions, the luminance (relative luminance) of the image light can be controlled according to its reflection angle (the vertical direction is 0 degrees). In this embodiment, such a lenticular lens can make the luminance characteristics in the vertical direction steeper as shown in Fig. 16(B) compared to the prior art. Furthermore, by changing the balance of the directivity characteristics in the up-and-down (positive and negative directions of the Y-axis) direction, the luminance (relative luminance) of the light due to reflection or diffusion can be increased. Due to these operational effects, for image light with a narrow diffusion angle (high straightness) and only a specific polarization component, such as image light from a surface-emitting laser image source, the ghost image generated by the retroreflective member when using a conventional image display device can be suppressed, and the spatially floating image due to retroreflection can be efficiently controlled to reach the viewer's eyes.

[0102] Also, by each of the above-described light source devices, it is possible to realize a directivity characteristic with a significantly narrower angle in both the X-axis direction and the Y-axis direction with respect to the light emission diffusion characteristics (denoted as conventional in the figure) from the general liquid crystal display panel 11 shown in Figs. 16(A) and (B). As a result, an image display device that emits light of a specific polarization that emits an image light beam that is nearly parallel to a specific direction can be realized.

[0103] FIG. 15 shows an example of the characteristics of the lenticular lens adopted in this embodiment. In this example, particularly, the characteristics in the X direction (vertical direction) are shown. For characteristic O, the peak of the light emission direction is at an angle of around 30 degrees upward from the vertical direction (0 degrees), showing a luminance characteristic that is symmetric up and down. Also, characteristics A and B in FIG. 15 show examples of characteristics in which the video light above the peak luminance is condensed at around 30 degrees to increase the luminance (relative luminance). Therefore, in these characteristics A and B, at angles exceeding 30 degrees, the luminance (relative luminance) of the light rapidly decreases compared to characteristic O.

[0104] That is, according to the optical system including the above-described lenticular lens, when the video light beam from the video display device 1 is incident on the retroreflective member 2, the emission angle and the viewing angle of the video light aligned at a narrow angle by the light source devices 13 and 230 can be controlled, and the degree of freedom in installing the retroreflective member 2 can be significantly improved. As a result, the degree of freedom in the relationship of the imaging position of the spatial floating image 3 that is reflected or transmitted through the windshield 105 and imaged at a desired position can be significantly improved. As a result, it becomes possible to efficiently reach the eyes of outdoor or indoor viewers as light with a narrow diffusion angle (high straightness) and only a specific polarization component. According to this, even if the intensity (luminance) of the video light from the video display device 1 is reduced, the viewer can accurately recognize the video light and obtain information. In other words, by reducing the output of the video display device 1, it becomes possible to realize a spatial floating image display system with low power consumption.

[0105] As described above in detail for various embodiments, however, the present invention is not limited to only the above-described embodiments and includes various modifications. For example, the above-described embodiments have described the entire system in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can also be added to the configuration of one embodiment. Further, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0106] In the technology according to this embodiment, by displaying a spatial floating image with high-resolution and high-brightness video information in a spatially floating state, for example, a user can operate without feeling anxiety about the contact infection of infectious diseases. If the technology according to this embodiment is used in a system used by an unspecified number of users, it is possible to reduce the risk of contact infection of infectious diseases and provide a non-contact user interface that can be used without feeling anxiety. Thereby, it contributes to "3 Ensure healthy lives and promote well-being for all" of the Sustainable Development Goals (SDGs) proposed by the United Nations.

[0107] Also, in the technology according to this embodiment, by reducing the divergence angle of the emitted video light and further aligning it to a specific polarization, only the regular reflected light can be efficiently reflected to the retroreflective member, so the light utilization efficiency is high, and it is possible to obtain a bright and clear spatial floating image. According to the technology according to this embodiment, it is possible to provide a non-contact user interface with excellent usability that can significantly reduce power consumption. Thereby, it contributes to "9 Build the infrastructure for industry and technological innovation" and "11 Make cities inclusive, safe, resilient and sustainable" of the Sustainable Development Goals (SDGs) proposed by the United Nations.

[0108] Furthermore, in the technology according to this embodiment, it is possible to form a spatial floating image with video light having high directivity (linearity). In the technology according to this embodiment, even when displaying videos that require high security in bank ATMs, ticket vending machines at stations, etc., or videos with high confidentiality that need to be concealed from people facing the user directly, by displaying video light with high directivity, it is possible to provide a non-contact user interface with less risk of the spatial floating image being spied on by people other than the user. Thereby, it contributes to "11 Make cities inclusive, safe, resilient and sustainable" of the Sustainable Development Goals (SDGs) proposed by the United Nations.

Explanation of Reference Numerals

[0109] 1: Video display device 1a: Image display unit 1b: Image control unit 1c: Image signal receiving unit 1d: Receiving antenna 2: Retroreflective member 2a: Retroreflective part 3: Spatial floating image 11: Liquid crystal display panel 12: Absorptive polarizing plate 13: Light source device 13a: Light source device 14a~c: LED elements 15: LED collimator 16: Composite diffusing block 17: Light guide 18: LED collimator lens 18a: First diffusing plate 18b: Second diffusing plate 21: λ / 4 plate (polarization conversion element) 22: First light shielding member 23: Second light shielding member 24: Third light shielding member 25: Fourth light shielding member 30: Arrow 49: Reflective polarizing plate 50: Protective cover 52: Liquid crystal display panel 54: Light direction conversion panel 81: Optical element 100: Transparent member 100a: Window part 100b: Light shielding member 101: Polarization separation member 102: LED substrate 103: Heat sink 105: Windshield 106: Housing 107: Optical element 112: Absorptive polarizing plate 153: Concave part 154: Convex lens surface 156: Outer peripheral surface 157: Convex lens surface 161: Texture 170: Light guide 172: Light guide light reflecting part 172a: Reflecting surface 172b: Connecting surface 172c: λ / 4 plate 172d: Reflecting surface 173: Light guide exit surface 200: Reflective polarizing plate 201: LED element 202: LED substrate 203: Light guide 203a: Light receiving end face 204: Light beam direction conversion means 205: Reflective sheet 206: Reflective polarizing plate 207: Optical sheet 210: Natural light beam 211: PBS film 212: Reflective film 215: λ / 2 phase plate 216: Phase difference plate 220: Reflective light guide 220a: Reflecting surface 222: Concave-convex pattern 223: Light source unit 230: Light source device 270: Phase difference plate 271: Reflector 272: Reflecting surface 304: Reflective light guide 400: Reflective mirror 1027: Optical element polarization conversion element 2135: 2 phase plate 220: Light guide 222: Concave-convex pattern 223: Light source unit 224: Light shielding wall 225: Substrate G1~G6: First ghost image~Sixth ghost image R1: Normal image

Claims

1. A spatial floating image display device for forming a spatial floating image, comprising: a display panel; a light source device that supplies light with a specific polarization direction to the display panel; a retroreflective member provided with a retardation plate on a retroreflective surface; a polarization separation member in a space connecting the display panel and the retroreflective member; a housing; a transparent member provided as a window portion of the housing, wherein the polarization separation member once transmits specific polarized video light from the display panel toward the retroreflective member, converts the polarization at the retroreflective member to the other polarization, reflects it at the polarization separation member, and transmits the video light reflected by the polarization separation member through the transparent member which is the window portion, and displays a spatial floating image which is a real image outside the window portion; A spatial floating image display device, wherein light incident from the display panel to the retroreflective member is inclined obliquely upward with respect to the horizontal, and the retroreflective member is arranged such that the reflective surface of the retroreflective member is inclined downward with respect to the vertical direction.

2. The spatial floating image display device according to claim 1, wherein the video display surface of the display panel and the retroreflective surface of the retroreflective member are arranged to be parallel.

3. The spatial floating image display device according to claim 2, wherein the display position of the spatial floating image is a position determined according to the distance between the display panel and the polarization separation member.

4. The spatial floating image display device according to claim 1, wherein the polarization separation member is formed of a reflective polarizing plate or a metal multilayer film that reflects a specific polarization wave.

5. The spatial floating image display device according to claim 1, wherein an absorption type polarizing plate is provided on at least one surface of the transparent member which is the window portion.

6. The spatial floating image display device according to claim 1, wherein the transparent member which is the window portion is formed of a transparent body for a portion through which the video light passes, and a light shielding member for a portion through which the video light does not pass.

7. The spatial floating image display device according to claim 1, wherein an antireflection film is provided on the video display surface of the display panel, and the absorption type polarizing plate provided on the display panel absorbs reflected light.

8. The spatial floating image display device according to claim 1, wherein the display panel is configured to be provided at a position away from the window portion.

9. The spatial floating image display device according to claim 1, wherein the display panel is provided at a position where the video light emitted from the display panel cannot be visually recognized from the window portion.

10. The spatial floating image display device according to claim 1, wherein a spatial floating image is formed by the light emitted from the window portion, the light emitted from the window portion is once reflected by a reflection mirror, and the position and angle of the obtained spatial floating image can be changed by setting the angle of the reflection mirror to a desired angle with respect to the plane of the window portion.

11. The spatial floating image display device according to claim 10, wherein the reflection mirror that reflects the spatial floating image emitted from the window portion has a characteristic of high reflectivity for a specific polarization.

Images