Spatially-suspended video display device

Abstract

To provide a spatially-suspended video display device of a portable type that is compact and contributes to the sustainable development goals of "3 good health and well-being to all people" and "9 create the base for industry and technological innovation".SOLUTION: A spatially-suspended video display device comprises: a cylindrical housing with a housing upper part and a housing lower part; a window part which is provided at a part of the housing upper part, and transmits video light for forming a spatially suspended video; a video display device which is provided inside the housing upper part, and includes a light source device, and a display panel for generating and emitting video light based on the light from the light source device; a retroreflective member which is provided between the window part and the video display device, inside the housing upper part, in order to subject the video light from the video display device to retroreflection; and a battery charger accommodated in the housing lower part.SELECTED DRAWING: Figure 6C

Description

[Technical field]

[0001] The present invention relates to a space floating image display device. [Background technology]

[0002] As an example of a floating-in-space image display device, Patent Document 1 discloses the following description: "The CPU of the information processing device includes an approach direction detection unit that detects the direction from which the user approaches the image formed in the air, an input coordinate detection unit that detects the coordinates at which the input is detected, an operation reception unit that processes the reception of operations, and an operation screen update unit that updates the operation screen in accordance with the received operations. When the user approaches the image from a predetermined direction, the CPU accepts the user's movement as an operation and executes processing in accordance with the operation (summary excerpt)." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-128722 A Summary of the Invention [Problem to be solved by the invention]

[0004] Although the above-mentioned floating-in-space image display device of Patent Document 1 can improve the operability of the floating-in-space image, it does not take into consideration the improvement of the apparent resolution or contrast of the floating-in-space image, and the reality is that further improvement in image quality is required.

[0005] Here, the floating image display device has a wide range of uses, and if it is used as a signage (advertising billboard), it will attract the attention of many people due to the novelty of "images floating in space", which is not possible with conventional flat displays. Also, as described in Patent Document 1, if the floating image is used as a human interface for performing some kind of operation, its contactless characteristic can prevent viral infections that are transmitted through contact parts such as push buttons.

[0006] On the other hand, there have been no examples of using a floating image display device as a portable device in the past. For example, if a floating image display device can be easily carried with one hand and the floating image can be displayed at a place and time of the user's choice, it can be used not only as a part of an entertainment system, but also as a means of notifying users of information, and the use of floating images can be greatly expanded.

[0007] In particular, if a floating image device could be easily installed inside a vehicle such as an automobile, images of people or the like displayed as floating images (hereinafter referred to as a concierge) could provide, for example, route directions or POI (Point Of Interest) information to the driver or passengers. Conversely, the driver or passengers could instruct the concierge on air conditioner temperature settings, music selections, etc. by voice or other means, and the concierge could respond with images and voice. This would enable driving assistance that is visually more fun, safer, and more comfortable than instructions given by normal button operations.

[0008] The object of the present invention is to provide a space-floating image display device capable of displaying suitable space-floating images with high visibility, and further to provide a space-floating image display device that is small (compact) and portable, suitable for mounting in a vehicle, etc. [Means for solving the problem]

[0009] In order to solve the above problem, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above problem, and an example thereof is as follows. The space floating image display device includes a cylindrical housing having an upper housing portion and a lower housing portion, a window portion provided in a part of the upper housing portion and transmitting image light for forming a space floating image, an image display device provided inside the upper housing portion and having a light source device and a display panel that generates and emits image light based on light from the light source device, a retroreflective member provided inside the upper housing portion between the window portion and the image display device, and retroreflective to reflect the image light from the image display device, and a rechargeable battery stored in the lower housing portion. Effect of the Invention

[0010] According to the present invention, a space-floating image display device capable of displaying suitable and highly visible space-floating images can be realized, and furthermore, by making the space-floating image display device small, lightweight, and portable, the space-floating image display device can be used anytime and anywhere, and in particular, by making the shape of the device capable of being installed and stored in a bottle holder or the like in a vehicle in consideration of its use in the vehicle, the user's convenience can be greatly improved. Problems, configurations, and effects other than those described above will be made clear by the following description of the embodiment. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image display device according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image display device according to an embodiment of the present invention; [Diagram 3] 1A and 1B are diagrams illustrating problems with the space floating image display device. [Figure 4] 4 is a characteristic diagram showing the relationship between the surface roughness of a retroreflective member and the amount of blur of a retroreflected image. FIG. [Diagram 5] 1A and 1B are diagrams illustrating problems with the space floating image display device. [Figure 6A]1 is a diagram showing another embodiment of the main components of a space floating image display device according to an embodiment of the present invention; [Figure 6B] 1 is a diagram showing the appearance of a space floating image display device that can be installed in a bottle holder according to an embodiment of the present invention; [Figure 6C] 1 is a diagram showing a main configuration of a space floating image display device that can be installed in a bottle holder according to an embodiment of the present invention; [Figure 6D] 1A and 1B are diagrams illustrating an example of a state of a space floating image display device installed in a bottle holder according to an embodiment of the present invention. [Figure 6E] FIG. 13 is a diagram showing an example of a floating-in-space image. [Figure 6F] 1A and 1B are diagrams showing an example of the configuration of a lid of a space floating image display device that can be installed in a bottle holder according to an embodiment of the present invention. [Figure 7] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 8] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 9] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 10] 1 is a layout diagram showing a main part of a space floating image display device according to an embodiment of the present invention; [Figure 11] 1 is a cross-sectional view showing a configuration of an image display device constituting a space floating image display device according to an embodiment of the present invention; [Figure 12] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 13] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 14] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 15] FIG. 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 16] FIG. 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 17] 1 is a cross-sectional view showing a configuration of an image display device constituting a space floating image display device according to an embodiment of the present invention; [Figure 18] FIG. 2 is a diagram showing an example of a specific configuration of a light source device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the disclosed embodiments, and various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed in this specification. In addition, in all the drawings for explaining the present invention, the same reference numerals are given to parts having the same functions, and repeated explanations may be omitted.

[0013] The following embodiment relates to a space-floating image display device that can display an image generated by image light from a large-area image light source through a transparent member that divides a space, such as a glass of a show window, as a space-floating image inside or outside the space of a store. The embodiment also relates to a large-scale digital signage system that is configured using a plurality of such space-floating image display devices.

[0014] According to the following embodiment, for example, high-resolution image information can be displayed in a state of floating in space on the glass surface of a show window or a light-transmitting plate material. At this time, according to the following embodiment, the divergence angle of the emitted image light is made small, i.e., an acute angle, and further aligned with a specific polarization, so that only the normal reflected light is efficiently reflected by the retroreflective member, so that the light utilization efficiency is high, and ghost images that occur in addition to the main space floating image, which was a problem in the conventional retroreflective method, can be suppressed, and a clear space floating image can be obtained. In addition, a device including the light source of this embodiment can provide a new space floating image display device that can significantly reduce power consumption and has excellent usability. In addition, for example, a space floating image display device that can display a so-called unidirectional space floating image that can be viewed outside the vehicle through a shield glass including the vehicle's front windshield, rear windshield, and side glass can be provided.

[0015] On the other hand, in conventional space-floating image display devices, an organic EL panel or a liquid crystal display panel is combined with a retroreflective member as a high-resolution color display image source. In conventional space-floating image display devices, image light is diffused at a wide angle, and the retroreflective part is a hexahedron, so in addition to the reflected light that is normally reflected, ghost images are generated by the image light that is obliquely incident on the retroreflective member 2 (retroreflective sheet) as shown in FIG. 3, which impairs the image quality of the space-floating image. Since the retroreflective member (retroreflective part 2a) shown as the conventional technology is a hexahedron, multiple ghost images are generated from the first ghost image G1 to the sixth ghost image G6 in addition to the normal image R1 of the space-floating image as shown in FIG. 5. For this reason, the ghost images, which are the same space-floating image, can be monitored by people other than the viewer, which poses a major security issue.

[0016] In addition, in the case of a floating image obtained by reflecting image light from an image display device with a narrow-angle directional characteristic (described later) using a retroreflective material, in addition to the ghost images described above, blurring was visible for each pixel of the liquid crystal display panel, as shown in Figure 4.

[0017] <Space-floating image display device (1)> FIG. 1 shows an example of a usage form of a space-floating image display device according to an embodiment of the present invention. FIG. 1(A) shows the overall configuration of the space-floating image display device according to this embodiment. For example, in a store or the like, a show window (window glass 105) that is a light-transmitting member (transparent member) such as glass divides the space. According to the space-floating information display device of this embodiment, it is possible to transmit the transparent member and display a space-floating image in one direction to the outside of the store space. Specifically, light with a narrow-angle directional characteristic and specific polarization is emitted from the image display device 1 as an image light beam, once enters the retroreflection member 2, is retroreflected and transmits the window glass 105 to form a real aerial image (space-floating image 3) outside the store. In FIG. 1, the inside of the window glass 105 (inside the store) is shown in the depth direction and the outside (for example, the sidewalk) is shown in the foreground. On the other hand, it is also possible to reflect the specific polarization by providing a means for reflecting the specific polarization in the window glass 105 and form an aerial image at a desired position inside the store.

[0018] FIG. 1B is a block diagram showing the configuration of the above-mentioned 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 an input image to match the resolution of the panel, an image signal receiving unit 1c that receives an image signal, and a receiving antenna 1d. The image signal receiving unit 1c is compatible with wired input signals such as USB (Universal Serial Bus: registered trademark) input and HDMI (High-Definition Multimedia Interface: registered trademark) input, and wireless input signals such as Wi-Fi (Wireless Fidelity: registered trademark), and functions independently as an image receiving and display device, and can display image information from a tablet, smartphone, etc. Furthermore, by connecting a stick PC, etc., it can be given the ability to perform calculation processing and image analysis processing.

[0019] Fig. 2 shows an example of the main part configuration and the retroreflection part configuration of a space floating image display device according to an embodiment of the present invention. The configuration of the space floating image display device will be described in more detail with reference to Fig. 2. As shown in Fig. 2(A), an image display device 1 that diverges specific polarized image light at a narrow angle is provided in the oblique direction of a transparent member 100 such as glass. The image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates specific polarized light having a narrow-angle diffusion characteristic.

[0020] The image light of a specific polarization from the image display device 1 is reflected by a polarization separation member 101 having a film that selectively reflects the image light of a specific polarization provided on a transparent member 100, and enters the retroreflective member 2. In the example in FIG. 2, the polarization separation member 101 is formed in a sheet shape and adhered to the transparent member 100. A λ / 4 plate 21 is provided on the image light incidence surface of the retroreflective member 2. The image light is polarized and converted from the specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, when entering the retroreflective member 2 and when exiting. Here, the polarization separation member 101 that selectively reflects the image light of a specific polarization has a property of transmitting the polarized light of the other polarization that has been polarized and converted, so that the image light of the specific polarization after polarization conversion passes through the polarization separation member 101. The image light that has passed through the polarization separation member 101 forms a space floating image 3, which is a real image, outside the transparent member 100.

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

[0022] Depending on the performance of the retroreflective member 2, the polarization axis of the reflected image light may become misaligned. In this case, a part of the image light with the misaligned polarization axis is reflected by the above-mentioned polarization separation member 101 and returns to the image display device 1. This light may be reflected again on the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating a ghost image and degrading the image quality of the floating-in-space image 3. Therefore, in this embodiment, an absorbing polarizing plate 12 is provided on the image display surface of the image display device 1. The image light emitted from the image display device 1 is transmitted through the absorbing polarizing plate 12, and the reflected light returning from the polarization separation member 101 is absorbed by the absorbing polarizing plate 12. This makes it possible to suppress the above-mentioned re-reflection and prevent degradation of image quality due to ghost images of the floating-in-space image.

[0023] The above-mentioned polarization separation member 101 may be formed, for example, of a reflective polarizing plate or a metal multilayer film that reflects a specific polarized wave.

[0024] Next, Fig. 2(B) shows the surface shape of a typical retroreflective member 2 manufactured by Nippon Carbide Industrial Co., Ltd., which was used in this study. In the retroreflective member 2, a light ray incident on the inside of the retroreflective portion 2a consisting of regularly arranged hexagonal prisms is reflected by the wall and bottom surfaces of the hexagonal prisms and is emitted as retroreflected light in a direction corresponding to the incident light, forming a normal image R1 shown in Fig. 5. Meanwhile, as shown in Fig. 3, ghost images (ghost images G1 to G6 in Fig. 5) are formed in addition to the normal image R1 depending on the image light from the image display device 1 that is obliquely incident on the retroreflective member 2.

[0025] Therefore, the space floating image display device of this embodiment displays a space floating image 3, which is a real image, without forming a ghost image, based on the image displayed on the image display device 1 of the present invention. The resolution of this space 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, if the diameter D of the retroreflective portion 2a is 240 μm and the pitch is 300 μm, one pixel of the space floating image 3 is equivalent to 300 μm. Therefore, the effective resolution of the space floating image 3 is reduced to about 1 / 3. Therefore, in order to make the resolution of the space floating image 3 equivalent to the resolution of the image display device 1, it is desirable to make the diameter D and pitch P of the retroreflective portion 2a close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moire caused by the retroreflective member 2 and the pixels of the liquid crystal display panel 11, it is preferable to design the pitch ratio of each to be a different integer multiple of one pixel. Also, it is preferable to arrange the retroreflective portion 2a in a shape such that none of its sides overlaps any of the sides of one pixel of the liquid crystal display panel 11.

[0026] The inventors have created an image display device 1 that combines a liquid crystal display panel with a pixel pitch of 40 μm with a light source of the present invention with a narrow divergence angle (divergence angle of 15°) to obtain the relationship between the amount of blur l of the image of the floating image in space that is permissible for improving visibility and the pixel size L through an experiment. FIG. 4 shows the experimental results. It was found that the amount of blur l that deteriorates visibility is preferably 40% or less of the pixel size L, and that if it is 15% or less, it is hardly noticeable. In this case, the surface roughness of the reflective surface at which the amount of blur l is permissible is an average roughness of 160 nm or less within a measurement distance of 40 μm, and it was found that in order to obtain a less noticeable amount of blur l, the surface roughness of the reflective surface is preferably 120 nm or less. For this reason, it is desirable to reduce the surface roughness of the retroreflective member 2 described above, and to set the surface roughness of the reflective film and its protective film that form the reflective surface to the above-mentioned value or less.

[0027] On the other hand, in order to manufacture the retroreflective member 2 at a low cost, it is preferable to use a roll press method. Specifically, this is a method in which the retroreflective portions 2a are aligned and shaped on a film. In this method, the inverse shape of the shape to be shaped is formed on the roll surface, and an ultraviolet-curable resin is applied onto a base material for fixing and passed between the rolls to form the required shape and cure it by irradiating ultraviolet rays, thereby obtaining the retroreflective member 2 of the desired shape.

[0028] The image display device 1 of the present invention, by using a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics described below, makes it possible to realize a structurally excellent system in which there is little possibility of an image being incident on the above-mentioned retroreflective member 2 at an angle, the occurrence of ghost images is prevented, and even if a ghost image does occur, the brightness of the ghost image is low.

[0029] <Space-floating image display device (2)> 6A shows another example (second example) of the main part configuration of a space floating image display device according to an embodiment of the present invention. The image display device 1 is configured with 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 configured with a liquid crystal display panel of a selected size, ranging from a small one with a screen size of about 5 inches to a large one exceeding 80 inches. The image light from the liquid crystal display panel 11 is reflected toward the retroreflective member 2 by a polarization separation member 101 such as a reflective polarizing plate.

[0030] A λ / 4 plate 21 is provided on the light incidence surface of the retroreflective member 2, and the image light is polarized by passing through the λ / 4 plate 21 twice, i.e., a specific polarized wave (one polarized wave) is converted into the other polarized wave. As a result, the other polarized wave after the polarization conversion is transmitted through the polarization separation member 101, and a real image, a floating image 3, is formed and displayed outside the transparent member 100. An absorbing polarizing plate 112 is provided on the external light incidence surface of the transparent member 100. In the above-mentioned polarization separation member 101, the polarization axis may become uneven due to the retroreflection of light, so that a part of the image light is reflected and returned to the image display device 1. This light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating the above-mentioned ghost image and significantly degrading the image quality of the floating image 3 in space. Therefore, in this embodiment, an absorbing polarizing plate 12 is provided on the image display surface of the image display device 1. The absorptive polarizing plate 12 transmits the image light and absorbs the above-mentioned reflected light, thereby preventing degradation of image quality due to ghost images of the spatially floating image 3.

[0031] In order to reduce image quality degradation caused by external light such as sunlight or illumination from outside the set of this spatial floating image display device, it is advisable to provide an absorptive polarizing plate 112 on the surface of the transparent member 100. Furthermore, since external light entering the retroreflective member 2 generates a strong ghost image, the fourth light blocking member 25 is used to prevent the entrance of external light. The polarization separation member 101 is formed of a reflective polarizing plate or a metal multilayer film that reflects specific polarized waves.

[0032] Between the polarization separation member 101 and the liquid crystal display panel 11, a second light shielding member 23 and a third light shielding member 24 are provided to shield oblique image light other than normal image light (normal image R1 in FIG. 5) that forms the spatial floating image 3. In addition, a first light shielding member 22 is provided between the retroreflective member 2 and the polarization separation member 101 to shield oblique image light other than normal image light. Furthermore, as described above, a fourth light shielding member 25 is also provided to block oblique light that generates ghost images so that external light is not directly incident on the retroreflective member 2. As a result, the generation of ghost images can be suppressed.

[0033] The inventor confirmed through an experiment that the effect of light shielding can be improved by providing the third light shielding member 24 and the second light shielding member 23 in the space between the liquid crystal display panel 11 and the polarization separation member 101. In this experiment, the inner diameter of the second light shielding member 23 and the third light shielding member 24 was set to 110% in area with respect to the area through which the normal image light beam that forms the space floating image 3 passes, and the parts were manufactured and assembled within the range of mechanical tolerance. In order to further reduce the occurrence of ghost images, the occurrence of ghost images could be suppressed to a level that does not cause practical problems if the inner diameter was set to 104% or less with respect to the area through which the normal image light beam of the above-mentioned light shielding member passes. On the other hand, the occurrence of ghost images can be further reduced by setting the distance L1 between the first light shielding member 22 and the retroreflective member 2 to 50% or less of the distance between the retroreflective member 2 and the polarization separation member 101, and the occurrence of ghost images could be reduced to a level that does not cause practical problems when viewed visually at 30% or less. Furthermore, by providing the fourth light shielding member 25, the first light shielding member 22, the second light shielding member 23, and the third light shielding member 24 in a manner surrounding the retroreflective member 2, the level of ghost images could be further reduced.

[0034] 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 area through which the normal image light beam that forms the spatial floating image 3 passes (corresponding to the area through which the image light beam passes in the absorptive polarizing plate 112 in this embodiment). It is even better if the cross-sectional shape of the light shielding member is configured to have a beam toward the inner surface, and the abnormal light that forms the ghost image is reflected multiple times on the surface of the beam to absorb the abnormal light. The area through which the normal image light beam passes is made smaller with respect to the outer frame of the light shielding member, and is made the same area as the surface inscribed by the beam.

[0035] On the other hand, the shape of the retroreflective member 2 may be a concave or convex surface with a curvature radius of 200 mm or more from the flat shape facing the image display device 1. In this way, even if a ghost image is generated by the oblique image light reflected by the retroreflective member 2, the ghost image generated after reflection may be made invisible by moving it away from the viewer's field of vision. A new problem occurs in that the amount of light reflected normally among the light reflected around the retroreflective member 2 with a curvature radius of 100 mm or less decreases, and the peripheral light amount of the obtained floating image 3 decreases. For this reason, in order to reduce the ghost image to a level that does not cause practical problems, it is advisable to select and apply the above-mentioned technical means or use them in combination.

[0036] <Space-floating image display device (3)> FIG. 6B is a perspective view showing an example of the appearance of a space-floating image display device (third example) according to an embodiment of the present invention. As shown in the figure, the space-floating image display device shown in FIG. 6B has a generally cylindrical, particularly cylindrical, housing 106. The space-floating image display device having this cylindrical housing 106 can be stored in a bottle holder (also called a drink holder, FIG. 6D described later) in a vehicle, and is a relatively small (compact) and portable space-floating image display device. This cylindrical shape is such that the axis of the cylinder extends in the height direction (corresponding to the vertical direction, Z direction in FIG. 6C) and the diameter of the cylinder extends in the direction perpendicular to the height direction (corresponding to the horizontal direction, X and Y directions in FIG. 6C). This cylindrical housing 106 has a housing upper part 601 and a housing lower part 602, which are connected together. Inside the housing 106, an optical system and a control circuit board described later, and a rechargeable battery, etc. are stored as necessary.

[0037] This cylindrical housing 106 has rigidity, light-shielding properties, waterproofing properties, etc., and has curved side surfaces 606, 607 as well as upper surface 603 and lower surface 608, which enclose the interior space of the housing.

[0038] As an example of the size of this cylindrical housing 106, the height is about 20 cm, the diameter of the upper housing upper part 601 is about 9 cm, and the diameter of the lower housing lower part 602 is about 7 cm. The size of the floating image 3 in space corresponds to the screen size of the liquid crystal display panel 11 and the size of the window part 605, and can be, for example, 2 to 3 inches. The distance (distance 690 in FIG. 6C) corresponding to the optical path length from the window part 605 to the position where the floating image 3 is formed is, for example, about 6 cm.

[0039] In this embodiment, the diameter of the upper housing 601 is larger than that of the lower housing 602. This configuration is a configuration that takes into consideration that the lower housing 602 is accommodated in the internal space of the bottle holder and the upper housing 601 is exposed to the upper side of the bottle holder. At the same time, this configuration is a configuration in which the upper housing 601 can accommodate an optical system with a volume larger than that of the lower housing 602. As a result, in the optical system in the upper housing 601, a larger element can be easily arranged, and a longer optical path length can be easily secured, and a longer protrusion distance (distance 690 in FIG. 6C) can be secured from the housing 106 (slope 604) to the formation position of the floating image 3. In addition, the screen size of the liquid crystal display panel 11 can be made larger, and the size of the floating image 3 can be made larger accordingly. The relationship between the diameters of the lower housing 602 and the upper housing 601 is not limited to the above, and a configuration in which the diameters of the lower housing 602 and the upper housing 601 are the same, or a configuration in which the diameter of the upper housing 601 is smaller than the diameter of the lower housing 602 is also possible.

[0040] As shown in the figure, the upper part 601 of the housing has a shape in which a part of a cylinder including a top surface 603 and a side surface 606 is obliquely cut out, and thus the top surface 603 is provided with a roughly semicircular region and a slope 604 is provided with a roughly semicircular region. The slope 604 is provided with a rectangular window (in other words, an opening) 605 in which the transparent member 100 and the like are arranged. The window (opening) 605 is a part for emitting image light to the outside. The image light from the optical system in the housing 106 passes through the window (opening) 605 and forms the floating image 3 at a position at a predetermined distance outside the housing 106 as shown in the figure. The shape of the window (opening) 605 is rectangular as an example, but is not limited to this and various shapes such as a circle, an ellipse, and a polygon are possible.

[0041] In this embodiment, the angle of the inclined surface 604 and the window portion 605 is, for example, about 45 degrees with respect to the upper surface 603 (angle α3 in FIG. 6C). Correspondingly, the optical axis of the floating image 3 (optical axis A3 in FIG. 6C) is an optical axis in a diagonal upward direction of about 45 degrees from the horizontal plane (W direction in FIG. 6C). The angle and direction of the inclined surface 604 and the optical axis arrangement are designed in consideration of the fact that the floating image display device is easily directed toward the driver's face when installed in a bottle holder (FIG. 6D) in a vehicle. The configuration of the angle and direction of the inclined surface 604 and the optical axis arrangement is not limited to this. For example, the angle α3 and the elevation angle of the optical axis A3 may be set within a predetermined angle range (for example, 45 degrees ± 15 degrees).

[0042] Fig. 6C shows an example of the internal configuration of the portable space floating image display device shown in Fig. 6B. An optical system for generating the space floating image 3 is mainly housed in the upper housing 601, and a control board 610 and a rechargeable battery 611 are mainly housed in the lower housing 602. The control board 610 and elements of the optical system such as the image display device 1 are mutually connected by signal lines or the like.

[0043] The upper housing 601 is provided with an optical system for generating a highly visible floating image 3 without ghost images. The optical system of the upper housing 601 is configured to include an image display device 1 (light source device 13, liquid crystal display panel 11, and absorptive polarizer 12 in FIG. 6C), a flat mirror 4, a beam splitter (in other words, a polarization separation member) 101, a retroreflective member 2 and a λ / 4 plate 21 which is a retardation plate, a transparent member 100, and an absorptive polarizer 112.

[0044] The rechargeable battery 611 in the lower housing 602 is a rechargeable battery such as a lithium ion battery or a power supply circuit. The control board 610 is a control circuit board that constitutes a video control unit and a video / audio signal transmission / reception unit, and is equipped with a processor, memory, interface, etc., in other words, is a controller for this space floating image display device. The control board 610 is disposed, for example, vertically long in a partial area inside the lower housing 602. The control board 610 may be equipped with a communication interface function, and may transmit and receive data to the Internet, etc.

[0045] The lower part 602 of the housing 106 is housed in the bottle holder. In this space-floating image display device, the optical system is housed in the upper part 601 of the housing 106, which is a vertically long cylinder, and a rechargeable battery 611, which is relatively heavier than the optical system, and the like are housed in the lower part 602 of the housing. The center of gravity of the entire space-floating image display device is located at the bottom. This allows the space-floating image display device to be stably held in the bottle holder. In addition, this space-floating image display device is relatively stable against vibrations such as vehicle swaying.

[0046] In this embodiment, the length in the height direction of upper housing 601 is greater than the length in the height direction of lower housing 602. The length in the height direction of upper housing 601 is limited to a certain length, taking into consideration the ability to stably hold the device with lower housing 602 housed in the bottle holder.

[0047] An input / output terminal 5 is provided on, for example, one location on the side surface 606 of the upper portion 601 of the housing 106. The input / output terminal 5 is connected to a control board 610. The input / output terminal 5 is a power input and signal input / output terminal, for example, a USB terminal, but is not limited thereto. The input / output terminal 5 is provided as, for example, a terminal for supplying power from a cigarette lighter socket of a vehicle, and a terminal for taking in various information including a video signal to be output as a floating-in-space video 3 (concierge, etc.). The control board 610 supplies the video signal input from the outside through the input / output terminal 5 to the video display device 1. Alternatively, the video signal input from the outside through the input / output terminal 5 may be directly supplied to the video display device 1.

[0048] Input / output terminal 5 may be provided as a plurality of input / output terminals, divided into a power input terminal and a signal input / output terminal. Input / output terminal 5 may be located anywhere on housing 106. Input / output terminal 5 may be located at one location on top surface 603, or at one location on side surface 607 of lower housing portion 602. In this embodiment, input / output terminal 5 on upper housing portion 601 can be easily accessed even when lower housing portion 602 is accommodated in the drink holder.

[0049] An on-board power supply can be connected to the input / output terminal 5. External power input from the on-board power supply (e.g., a cigarette lighter socket) is supplied to the rechargeable battery 611 via the input / output terminal 5, and the rechargeable battery 611 is charged. The rechargeable battery 611 supplies power to each component such as the control board 610. Since this floating-in-space image device is small, the rechargeable battery 611 may be a dry cell. External input information, for example, input information from a car navigation system, is input to the control board 610 via the input / output terminal 5. Based on the input information, the control board 610 creates an image of a concierge or the like and a corresponding sound to be displayed as the floating-in-space image 3, and controls the image display device 1, etc.

[0050] This space-floating image display device can also be voice-controlled. Devices such as a microphone and a speaker may be connected to the input / output terminal 5 of the housing 106, or a car navigation system or a controller of an in-vehicle system may be connected. A user's smartphone or the like may be connected. In this case, voice input / output control is possible based on the control of the microphone and the like by the control board 610. That is, the control board 610 can input the voice uttered by the driver or the like from the microphone or the like, recognize the input voice, and perform processing corresponding to the recognized predetermined instruction (for example, display on / off, etc.). In addition, the control board 610 can read out the voice (for example, the voice uttered by the concierge) associated with the space-floating image 3 along with the display of the space-floating image 3, or create it by a voice synthesis function, and output it to the driver or the like from a speaker or the like. Not limited to these, a configuration in which a microphone, a speaker, etc. are mounted on the housing 106 of the space-floating image display device may be used.

[0051] 6D shows an example of the appearance of the portable space-floating image display device of this embodiment installed in a cylindrical bottle holder 600H in a vehicle. A driver or a passenger in the vehicle inserts the lower part 602 of the housing of the space-floating image display device into the bottle holder 600H in the vehicle and stores it there. The upper part 601 of the housing protrudes upward from the bottle holder 600H, and the image light emitted from the window part 605 forms the space-floating image 3.

[0052] The example of FIG. 6D is an example in which a bottle holder 600H is installed near the air conditioner above the part where the car navigation system and the like are installed near the center of the dashboard 6001 of the vehicle, and the space-floating image display device is installed in the bottle holder 600H. This example also shows a state in which the direction of the window part 605 of the space-floating image display device of the bottle holder 600H (i.e., the direction of the optical axis of the image light, the direction of the space-floating image 3) is adjusted so that it faces the face and eyes of the driver in the driver's seat on the right side. This direction can be adjusted by rotating the cylindrical housing 106 inside the bottle holder 600H. When a passenger wants to view the space-floating image 3, the direction of the window part 605 can be adjusted so that it faces the face and eyes of the passenger.

[0053] In addition, the bottle holder 600H is generally not limited to a vehicle-mounted type, and there are also types that can be attached and detached, and this space floating image display device can be installed in bottle holders in various positions, not limited to the example shown in the figure.

[0054] 6C, the optical system inside the housing 106 of this floating-in-space image display device is designed to match the cylindrical housing 106 that is suitable for installation in the bottle holder 600H. Each element of the optical system is arranged in correspondence with the long space in the height direction inside the cylindrical housing 106 (particularly the housing upper part 601), and the optical path is bent by the plane mirror 4 to ensure that the optical path length in the height direction is as long as possible.

[0055] In FIG. 6C, in the upper part 601 of the housing, the image display device 1, the flat mirror 4, the beam splitter 101, the retroreflective member 2, the transparent member 100, etc. are arranged in the order from bottom to top in the height direction. Each element is fixed to the upper part 601 of the housing in a predetermined relationship. More specifically, for example, the beam splitter 101, the retroreflective member 2, and the transparent member 100 (installed in the window part 605) are arranged so that one side of each of them is in contact with each other, or one side of each of them is close to each other with a predetermined interval. The housing 106 has a shape that is longer in the height direction than in the radial direction, and each element that constitutes the optical system is arranged as shown in the figure so as to secure as long as possible the optical path of the image light in the height direction. The image display device 1, the flat mirror 4, the retroreflective member 2, etc. are arranged in a state inclined obliquely with respect to the height direction, etc. The image display device 1 is arranged at an angle α1. The retroreflective member 2 is arranged at an angle α2. The beam splitter 101 is arranged horizontally. The inclined surface 604 and the transparent member 100 are disposed at an angle α3. The plane of the plane mirror 4 is also disposed at an angle α4, with the plane being slightly inclined with respect to the vertical plane. The optical path of the image light in this optical system is the optical path reflected by the plane mirror 4. The optical path of the image light in this optical system is the optical path in which the beam splitter 101 is disposed between the plane mirror 4 and the retroreflective member 2.

[0056] The optical path of the image light in this optical system is an optical path that passes through, in order, the image display device 1, the flat mirror 4, the beam splitter 101, the λ / 4 plate 21, the retroreflective member 2, the λ / 4 plate 21, the beam splitter 101, the transparent member 100, and the absorptive polarizing plate 112, and then reaches the space-floating image 3. Points p1 to p6 are examples of points that the image light passes through on its optical path. Point p1 is a reference point (for example, a center point) of the image output surface of the liquid crystal display panel 11. Point p2 is a reference point of the flat mirror 4. Point p3 is a reference point of the beam splitter 101. Point p4 is a reference point of the retroreflective member 2. Point p5 is a reference point of the transparent member 100. Point p6 is a reference point of the space-floating image 3. This space floating image 3 can be most appropriately viewed when viewed by the user's eyes from the direction of arrow A corresponding to optical axis A3 (the direction directly facing the image surface).

[0057] The space-floating image display device shown in FIG. 6B etc. generates a space-floating image 3 at a position at a predetermined distance diagonally above the housing 106. For example, the space-floating image 3 may be the face of a person (concierge) who provides navigation information and POI information around the vehicle to the driver of the vehicle by video and audio. FIG. 6E shows a schematic diagram of a display example of a concierge in the space-floating image 3 as seen from the driver. The space-floating image 3 has a rectangular area of ​​a predetermined maximum size, for example, and an image 3001 of the concierge is displayed within the area. The image 3001 may be a moving image or a still image. In addition, in accordance with the display of the image 3001, a voice 3002 issued by the concierge (for example, a guide on the estimated time of arrival at the destination) is output from a speaker (an in-vehicle speaker or a speaker housed in the housing 106 of the space-floating image display device) or the like.

[0058] In FIG. 6C, the image display device 1 is configured to include 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 narrow-angle diffusion characteristics. Here, the liquid crystal display panel 11 is configured to be small, with a screen size of about 2 to 3 inches. In this embodiment, the image display surface of the image display device 1 is further provided with an absorbing polarizer 12. Alternatively, the image display device 1 is further configured to have an anti-reflection film (not shown) on the image output side of the absorbing polarizer 12 provided on the surface of the image display device 1, so that the light of the ghost image is transmitted and absorbed by the absorbing polarizer 12, thereby preventing degradation of image quality due to the ghost image.

[0059] With reference to FIG. 6C, the internal configuration and features of the portable space-floating image display device will be described in detail. The image display device 1, which is composed of a liquid crystal display panel 11, an absorptive polarizing plate 12, and a light source device 13, is arranged and fixed to a housing 106 at a predetermined angle (the optical axis is at an angle α1 with respect to the horizontal plane) as shown in the figure. The light source device 13 functions as a backlight that supplies illumination light having a narrow-angle diffusion characteristic to the liquid crystal display panel 11. The image light from the image display device 1 (point p1 with respect to the optical axis) is reflected on the plane mirror 4 (point p2), changes direction, and enters the beam splitter 101 (point p3). The image light further passes through the beam splitter 101 (point p3) and proceeds directly toward the retroreflective member 2 (point p4).

[0060] As will be described later in Figs. 8 and 9, the source light from light source device 13 can be S-polarized (vertical polarization) (Fig. 8) or P-polarized (parallel polarization) (Fig. 9). In either case, the source light from light source device 13 functions as a backlight for liquid crystal display panel 11. Correspondingly, the image light emitted from image display device 1 (liquid crystal display panel 11) (i.e., image light modulated by the liquid crystal display panel 11 with a signal from the image source based on the source light) can be S-polarized or P-polarized. Below, first, a case where the image light from image display device 1 is image light having the characteristics of P-polarization will be described.

[0061] The image light (P polarized light) emitted from the liquid crystal display panel 11 and transmitted through the absorptive polarizer 12 first travels along the optical axis A1 toward the plane mirror 4. The image light (P polarized light) is reflected on the plane mirror 4 and travels along the optical axis A2 toward the beam splitter 101.

[0062] The beam splitter (polarized light separation member) 101 has a polarized light separation function, and is an element having a structure that transmits P-polarized light from the liquid crystal display panel 11 using the light source device 13 as a backlight, i.e., the image light from the image display device 1, but reflects (in other words, does not transmit) S-polarized light. Such a beam splitter 101 is formed of a reflective polarizing plate or a multilayer film that reflects a specific polarized wave. The multilayer film in this embodiment is a metal multilayer film.

[0063] Next, the image light (for example, P-polarized light) transmitted through the beam splitter 101 heads toward the retroreflective member 2. A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2. The image light (P-polarized light) from the beam splitter 101 as the image light (P-polarized light) from the image display device 1 passes through the λ / 4 plate 21 twice, at the time of incidence on the retroreflective member 2 and at the time of emission after reflection. This causes the image light to be polarized and converted from one polarized wave to the other polarized wave. That is, specifically, it is converted from P-polarized light to S-polarized light. As a result, the image light reflected by the retroreflective member 2 becomes image light having S-polarized light characteristics (image light having polarization characteristics different from the original image light) and heads toward the beam splitter 101. The image light (S-polarized light) is reflected by the beam splitter 101 and heads toward the transparent member 100 as the optical axis A3. The image light (S-polarized light) passes through the transparent member 100 and the absorptive polarizer 112 of the window portion 605 to the outside, and generates and displays the space floating image 3, which is a real image, at a position at a predetermined distance 690 outside the window portion 605.

[0064] Alternatively, in the opposite case to the above embodiment, the image light from the image display device 1 is S-polarized light, as follows. The S-polarized image light emitted from the image display device 1 is reflected by the plane mirror 4 and directed toward the beam splitter 101. In this case, the beam splitter 101 is an element having a structure that transmits the image light (S-polarized light) from the image display device 1 and reflects the P-polarized light in reverse. The image light (S-polarized light) from the beam splitter 101 is polarized and converted to P-polarized light by reflection from the retroreflective member 2 and passing twice through the λ / 4 plate 21. This image light (P-polarized light) is reflected by the beam splitter 101 and directed toward the transparent member 100, and forms the space floating image 3 by transmitting through the transparent member 100, etc.

[0065] The design of the polarization of the image light and the beam splitter 101 and the like can be applied to any of the embodiments. When the image light from the image display device 1 is S-polarized, there is an advantage that the reflectance at the plane mirror 4 is higher. When the image light from the image display device 1 is P-polarized, there is an advantage that the image light is easily visible even when the user is wearing polarized sunglasses and viewing the floating image 3.

[0066] Here, when the portable space floating image display device of this embodiment is installed inside a vehicle, it is known that most (about 80%) of the S-polarized light component of external light (sunlight or external illumination light) entering from outside the vehicle is reflected on the windshield (windshield), and the external light entering the inside of the vehicle is mostly P-polarized. Therefore, it is recommended to provide an absorbing polarizing plate 112 on the external light incidence surface of the transparent member 100.

[0067] The window 605 transmits the image light. The transparent member 100 is provided in the window 605 and is made of a glass plate or the like. An absorbing polarizing plate 112 is provided on the external light incidence surface of the transparent member 100. The transparent member 100 and the absorbing polarizing plate 112 are arranged in the portion of the window 605 of the inclined surface 604 that transmits the image light, and the other portion (i.e., a portion of the housing 106) is made of a light-shielding material so that external light does not enter the housing 106. The size of the window 605 corresponds to the size of the spatial floating image 3. Note that, in the transparent member 100 of the window 605, a portion (the portion that transmits the image light) may be formed of a transparent body, and the other portion may be formed of a light-shielding material.

[0068] In order to reduce degradation of image quality due to external light such as sunlight and illumination from outside the housing 106 that houses the image display device 1 and other optical components, an absorptive polarizing plate 112 is provided on the outer surface of the transparent member 100. Most of the external light is absorbed by the absorptive polarizing plate 112 and is unlikely to enter the upper housing 601.

[0069] In the beam splitter (polarization separation member) 101, the polarization axis may become misaligned due to the retroreflection of light, so that a part of the image light is reflected and returned to the image display device 1. This light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating the above-mentioned ghost image and significantly degrading the image quality of the spatially floating image 3. Therefore, in this embodiment, an absorbing polarizing plate 12 is further provided on the image display surface of the image display device 1. Alternatively, by providing an anti-reflection film (not shown) on the image output side of the absorbing polarizing plate 12 provided on the surface of the image display device 1, the light of the ghost image is transmitted and absorbed by the absorbing polarizing plate 12, thereby preventing degradation of image quality due to the ghost image.

[0070] When external light is directly incident on the retroreflective member 2, a strong ghost image may be generated. Therefore, in this embodiment, as shown in FIG. 6C, the retroreflective member 2 is arranged to be inclined obliquely downward at an angle α2, and the transparent member 100 of the window portion 605 and the retroreflective member 2 (particularly the retroreflective surface) are arranged in a relationship of about 90 degrees as shown in the figure. The main incident direction of the external light component that enters the inside from the outside through the transparent member 100 of the window portion 605 is the same direction as the optical axis A3 of the image light (direction perpendicular to the surface of the transparent member 100). In this case, the retroreflective member 2 and the λ / 4 plate 21 are arranged so that the direction of the optical axis of the retroreflective member 2 (direction perpendicular to the surface) is in a relationship of about 90 degrees. In other words, the retroreflective member 2 and the λ / 4 plate 21 are arranged so that the retroreflective surface of the retroreflective member 2 and the surface of the transparent member 100 are in a relationship of about 90 degrees. Even if external light components are incident on the inside of the upper housing 601, the retroreflective member 2 is disposed facing downward (at about 90 degrees in FIG. 6C) relative to the window portion 605 through which the external light enters, so that the external light components are unlikely to directly enter the retroreflective member 2. Therefore, the optical system configuration that prevents such external light from entering can prevent the occurrence of strong ghost images.

[0071] Moreover, the image display device 1 is also disposed at a position away from the window 605, with the beam splitter 101 and the plane mirror 4 interposed therebetween. The image display device 1 is disposed at a position where the image light of the optical axis A1 emitted from the image display device 1 cannot be seen from the direction of the arrow A (optical axis A3) through the window 605. This further reduces the occurrence of ghost images.

[0072] 6C, the optical path length from point p1 of the image display device 1 to point p3 of the beam splitter 101 via point p2 of the plane mirror 4 is correlated with the optical path length from point p3 of the beam splitter 101 to point p6 of the floating-in-space image 3. If the distance 690 forming the floating-in-space image 3 from the window portion 605 to the outside is secured to a certain extent, the floating feeling of the floating-in-space image 3 can be enhanced. Therefore, in this embodiment, as an optical system housed and arranged in a small, vertically long housing 106, each element is arranged at an angle and a plane mirror 4 is provided, thereby securing the optical path length from the image display device 1 to the beam splitter 101 as long as possible.

[0073] As described above, the small and portable space-floating image display device of this embodiment can be suitably installed in a bottle holder or the like in a vehicle, and can suitably provide the driver or the like with a space-floating image 3 of a concierge or the like. The cylindrical housing 106 can be suitably installed in a bottle holder that is standardly installed in a general vehicle, or a bottle holder of a type that can be attached and detached. The user can easily attach and detach this space-floating image display device to a bottle holder or a similar container or space as needed. In addition, by providing the input / output terminal 5 on the housing 106, this space-floating image display device can also feed power to the rechargeable battery 611 from a power source such as a cigarette lighter socket of the vehicle. Therefore, this device can always be charged even while driving, and there is no need to worry about the battery running out even when used for a long time.

[0074] The floating image 3 formed by the floating image display device of this embodiment has directivity with respect to the viewing direction, as described above. In order for the driver or passengers in the vehicle to view the floating image 3 in a bright image, it is most desirable to view it from a direction directly facing the floating image 3 (a direction aligned with the optical axis A3), as shown by the arrow A in FIG. 6C. In the absolute space coordinate system, the direction of the floating image 3 (optical axis A3) also depends on the position and orientation of the device installed in the drink holder. The relative direction when the driver or the like views the floating image 3 depends on the relationship between the position and orientation of the floating image 3 (optical axis A3) and the position and orientation of the driver's face and eyes.

[0075] Therefore, in this embodiment, assuming a bottle holder with an opening on the top in the vertical direction (FIG. 6D), the window 605 of the slope 604 and the corresponding optical system are designed so that when this space-floating image display device is installed in the bottle holder, the space-floating image 3 can be easily adjusted to face the driver's face and eyes. That is, the window 605 of the slope 604 is configured at about 45 degrees, and the optical axis A3 of the space-floating image 3 is diagonally upward at about 45 degrees. This makes it easy for the driver to view the space-floating image 3 as a bright image from directly in front without moving their head too much when viewing the space-floating image 3.

[0076] If the direction of the image light emitted from the space floating image display device is vertical or horizontal, the driver, etc., needs to move his / her head, etc., to match the direction of the image light and, for example, peer into it in order to view the space floating image from directly in front. According to this embodiment, such a need does not exist, and the bright space floating image 3 can be viewed in a relatively natural posture even while driving.

[0077] FIG. 6F shows a configuration example in which a lid is provided on the housing 106 as a modified example of the above embodiment. In FIG. 6F (A), a lid 651 like a bottle cap is provided on the housing upper part 601 so that the upper surface 603 and the window part 605 can be hidden according to the user's operation. When the space floating image display device is not in use, the lid 651 is attached as shown in the figure, thereby preventing scratches and adhesion of dirt to the window part 605 and increasing the strength. When the space floating image display device is in use, the lid 651 is removed.

[0078] FIG. 6F (B) shows another example of the configuration, in which the upper part 601 of the housing has a lid 652 provided on the window part 605. The shape of the lid 652 is, for example, a flat plate. One side of the lid 652 is connected to a hinge provided on the side where the upper surface 603 and the inclined surface 604 (FIG. 6B) meet, and the lid 652 rotates around the hinge as a rotation axis in response to a user's operation. When the space-floating image display device is not in use, as shown in the figure, the window part 605 is covered with the lid 652, thereby preventing scratches, dirt, etc. from adhering to the window part 605 and increasing its strength. When the space-floating image display device is in use, the lid 652 is rotated as shown by the arrow and placed on the upper surface 603, and the window part 605 is opened.

[0079] FIG. 6F (C) shows another example of the configuration, in which a lid 653 is provided in a space area in which a part of the cylinder near the window 605 is cut out in the upper part 601 of the housing. This lid 653 may be structured to rotate like the lid 652, but may also be structured to be attached to a protrusion or the like provided on a surface of the inclined surface 604 other than the window 605 as shown in the figure. When the space-floating image display device is not in use, as shown in the figure, the window 605 is covered with the lid 653, thereby preventing scratches and dirt from adhering to the window 605 and increasing its strength. When the space-floating image display device is in use, the lid 653 is removed and the window 605 is open. In addition, the housing 106 of the space-floating image display device may be provided with not only a lid but also a handle for carrying.

[0080] The following modifications are also possible. The cylindrical housing 106 is not limited to a cylinder, and various cross-sectional shapes on a horizontal plane are possible. The cross-sectional shape of the housing 106 may be rectangular (or polygonal), for example, to form a rectangular parallelepiped housing 106. The cylindrical housing 106 of the embodiment has the advantage that it can be accommodated just right in a cylindrical bottle holder. The rectangular parallelepiped housing 106 as a modification has the advantages of being easy to manufacture and easy to hold in the hand.

[0081] 6C, in order to make the device more compact, the beam splitter 101, the retroreflective member 2, and the transparent member 100 of the window portion 605 are arranged so that their sides are in contact with each other like a triangle. However, the present invention is not limited to this, and in order to ensure a longer optical path length, the sides of these elements may be arranged so that they are spaced apart from each other.

[0082] Although the above embodiment shows the case of being mounted on a vehicle, the portable floating image device can be used in various places because it can be carried by the user. For example, it can be installed in a container other than a bottle holder in the user's home. It can also be used by simply placing it on a desk or the like without storing it in a container.

[0083] The space-floating image display device may use a super-directional speaker as the speaker. The super-directional speaker is a speaker that outputs super-directional sound so that the output sound can be heard only in a specific spatial region near the user's ear. The space-floating image display device may also be equipped with a camera or a distance measuring sensor, and may be configured to detect touch operations, etc., of the user's fingers, etc. on the space-floating image 3 using them, and perform a predetermined process according to the detection. The space-floating image display device may also detect the presence or absence of a user based on a camera image or sensor detection, or may be configured to analyze and determine the user's face, etc., to perform user authentication. The space-floating image display device may also read a code, such as a barcode, from the card or paper, etc., based on a camera image, etc., when a card, paper, etc. is held over the space-floating image 3, and perform a process according to the code.

[0084] As a modified example, similar to the light-shielding member of FIG. 6A described above, a light-shielding member may be arranged in the space connecting the image display device 1 and the retroreflective member 2 via the beam splitter 101 (for example, the space below the beam splitter 101) to block image light having a divergence angle exceeding a specific angle from the liquid crystal display panel 11 from entering the retroreflective member 2.

[0085] In this embodiment, it is particularly preferable that the light source device 13 has the following configuration (details will be described later): The light source device 13 has a point or planar light source, optical means for reducing the divergence angle of light from the light source, polarization conversion means for aligning the light from the light source to a specific direction of polarization, and a light guide having a reflective surface for propagating the light from the light source to the liquid crystal display panel 11, and is configured to emit an image light flux having a narrow divergence angle as image light from the liquid crystal display panel 11 by controlling the light using the shape and surface roughness of the reflective surface of the light source device 13.

[0086] In this embodiment, the surface roughness of the retroreflective surface of the retroreflective member 2 is reduced to a predetermined value or less per unit length, thereby reducing the amount of blurring of the spatial floating image 3 and improving visibility. For example, the surface roughness of the retroreflective surface is set to 160 nm or less.

[0087] <Reflective polarizing plate> When the beam splitter 101 in this embodiment is a reflective polarizing plate with a grid structure, the characteristics for light from a direction perpendicular to the polarization axis are degraded. For this reason, specifications along the polarization axis are desirable, and the light source device of this embodiment capable of emitting the image light from the liquid crystal display panel 11 at a narrow angle is an ideal light source. Similarly, the characteristics in the horizontal direction are degraded for light from an oblique direction. In consideration of the above characteristics, a configuration example of this embodiment will be described below in which a light source (light source device 13) capable of emitting the 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. This makes it possible to provide a high-contrast floating image 3.

[0088] <Image display device> Next, the image display device 1 of this embodiment in Fig. 1 will be described with reference to Fig. 7. The image display device 1 of this embodiment includes a liquid crystal display panel 11, which is an image display element, and a light source device 13 that constitutes a light source for the liquid crystal display panel 11. Fig. 7 shows the light source device 13 together with the liquid crystal display panel 11 as an exploded perspective view.

[0089] As shown by the arrow 30 in Fig. 7, the liquid crystal display panel 11 obtains an illumination light flux with narrow-angle diffusion characteristics, i.e., strong directivity (in other words, linearity) and characteristics similar to laser light with a polarization plane aligned in one direction, by using light from the light source device 13, which is a backlight device, and emits image light modulated according to the input image signal. As a result, the emitted image light is reflected by the retroreflective member 2 and passes through the window glass 105 to form a real image, a floating image 3, as shown in Fig. 1.

[0090] 7, the image display device 1 is configured to include a liquid crystal display panel 11, a light direction conversion panel 54 for controlling the directional characteristics of the light beam emitted from the light source device 13, and a narrow-angle diffusion plate (not shown) as necessary. That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and as shown by the arrow 30 in FIG. 7, image light of a specific polarized wave is modulated in intensity by a video signal and emitted. As a result, the image display device 1 projects a desired image as light of a specific polarized wave with high directivity (linearity) through the light direction conversion panel 54 toward the retroreflective member 2, and after reflection by the retroreflective member 2, the light is transmitted toward the eyes of a viewer outside the space of the store in FIG. 1 to form a space floating image 3. Note that a protective cover 50 (see FIG. 8 and FIG. 9) may be provided on the surface of the light direction conversion panel 54 described above.

[0091] In this embodiment, in order to improve the utilization efficiency of the light beam emitted from the light source device 13 indicated by the arrow 30 in FIG. 7 and to significantly reduce power consumption, in the image display device 1 including the light source device 13 and the liquid crystal display panel 11, the light indicated by the arrow 30 from the light source device 13 is projected toward the retroreflective member 2 in FIG. 1, and after being reflected by the retroreflective member 2, the directivity can be controlled so that the space floating image 3 is formed at a desired position by a transparent sheet (not shown) provided on the surface of the window glass 105. Specifically, this transparent sheet controls the imaging position of the space floating image while giving high directivity by optical components such as a Fresnel lens or a linear Fresnel lens. According to this, the image light from the image display device 1 can efficiently reach the observer outside the window glass 105 (for example, on the sidewalk) with high directivity (straightness) like laser light, and as a result, it is possible to display a high-quality space floating image with high resolution and significantly reduce the power consumption of the image display device 1 including the LED (Light Emitting Diode) element 201 of the light source device 13.

[0092] <Example of image display device (1)> FIG. 8 shows another example of the image display device 1. FIG. 8 also 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 is configured by storing an LED element 201 and a light guide 203 therein. As shown in FIG. 8 and other figures, the end surface of the light guide 203 has a shape in which the cross-sectional area gradually increases toward the opposite side to the light receiving part in order to convert the divergent light from each LED element 201 into a substantially parallel light beam, and is provided with a lens shape that has an effect of gradually decreasing the divergence angle by multiple total reflections during propagation inside. The liquid crystal display panel 11 constituting the image display device 1 is attached to the upper surface of the light guide 203. In addition, the LED element 201, which is a semiconductor light source, and the LED board 202 on which the control circuit for the LED element 201 is mounted are attached to one side of the case of the light source device 13 (the end surface on the left side of FIG. 8 in this example). In addition, a heat sink, which is a member for cooling the heat generated by the LED elements 201 and the control circuit, may be attached to the outer surface of the LED substrate 202.

[0093] In addition, the liquid crystal display panel 11 is attached to a frame (not shown) of the liquid crystal display panel 11 attached to the upper surface of the case of the light source device 13, and further, an FPC (Flexible Printed Circuits: flexible wiring board) (not shown) electrically connected to the liquid crystal display panel 11 is attached to the frame. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown) constituting an electronic device together with the LED element 201, which is a solid light source. At this time, the generated image light has a narrow diffusion angle and contains only specific polarization components, so that a new image display device 1 that has not been seen before is obtained that is similar to a surface-emitting laser image source driven by an image signal. Note that, at present, it is technically and safety impossible to obtain a laser light beam of the same size as the image obtained by the above-mentioned image display device 1 using a laser device. Therefore, in this embodiment, light similar to the above-mentioned surface-emitting laser image light is obtained from a light beam from a general light source equipped with the LED element 201, for example.

[0094] 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. 8 and FIG. 9. Since FIG. 8 and FIG. 9 are cross-sectional views, only one of the LED elements 201 constituting the light source is shown. The light from the LED elements 201 is converted into approximately collimated light (approximately parallel light) by the shape of the light receiving end surface 203a of the light guide 203. For this reason, the light receiving portion of the light guide end surface and the LED element 201 are attached while maintaining a predetermined positional relationship. Each of the light guides 203 is formed of a translucent resin such as acrylic. The LED light receiving surface at the end of the light guide has, for example, a convex convex outer circumferential surface obtained by rotating a parabolic cross section, and at the top of the LED light receiving surface, a concave portion having a convex portion (i.e., a convex lens surface) formed in the center is formed, and at the center of the flat portion, a convex lens surface protruding outward (or a concave lens surface recessed inward) is formed. The outer shape of the light receiving part of the light guide 203 to which the LED element 201 is attached is a parabolic shape forming a conical outer surface, and is set within an angle range within which the light emitted from the LED element 201 in the peripheral direction can be totally reflected therein, or a reflective surface is formed.

[0095] On the other hand, the LED elements 201 are disposed at predetermined positions on the surface of an LED substrate 202, which is a circuit substrate for the LED elements 201. The LED substrate 202 is disposed and fixed to the LED collimator (light-receiving end surface 203a of the light guide 203) such that the LED elements 201 on the surface are positioned in the center of the recessed portion described above.

[0096] According to this configuration, the shape of light-receiving end surface 203a of light guide 203 makes it possible to extract the light emitted from LED element 201 as substantially parallel light, thereby improving the efficiency of use of the generated light.

[0097] As described above, the light source device 13 is configured by mounting a light source unit in which a plurality of LED elements 201 serving as light sources are arranged on the light-receiving end surface 203a serving as a light-receiving section provided on the end surface of the light guide 203, and the divergent light beam from the LED elements 201 is converted into substantially parallel light by the lens shape of the light-receiving end surface 203a of the light guide 203, and the light is guided inside the light guide 203 (in a direction parallel to the drawing) as shown 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. By optimizing the distribution (density) of the light beam direction conversion means 204 depending on the shape of the inside or surface of the light guide 203, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled.

[0098] The above-mentioned light beam direction conversion means 204 emits the light beam propagated inside the light guide 203 toward the liquid crystal display panel 11 arranged approximately parallel to the light guide 203 by providing a portion with a different refractive index inside the light guide 203 or by changing the shape of the surface of the light guide 203. At this time, when the brightness at the center of the screen of the liquid crystal display panel 11 is compared with that at the peripheral part of the screen while facing the center of the screen from a viewpoint at the same position as the diagonal dimension of the screen, if the relative brightness ratio is 20% or more, there is no practical problem, and if it exceeds 30%, it is an even better characteristic.

[0099] 8 and 9 are cross-sectional layout diagrams for explaining the configuration and operation of the light source (light source device 13) of this embodiment that performs polarization conversion in light source device 13 including the above-mentioned light guide 203 and LED element 201. FIG. 8 shows the case of converting P-polarized light to S-polarized light, and FIG. 9 shows the case of converting S-polarized light to P-polarized light. In FIG. 8 and FIG. 9, light source device 13 is composed of light guide 203 having light beam direction conversion means 204 on the surface or inside formed of plastic, LED element 201 as a light source, reflection sheet 205, retardation plate 216, lenticular lens, etc., and liquid crystal display panel 11 having polarizing plates on the light source light entrance surface and image light exit surface is attached to the upper surface of light source device 13 (light guide 203).

[0100] 8, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (lower surface) of the liquid crystal display panel 11 facing the light source device 13, and selectively reflects one polarized wave (e.g., P wave) 212 of the natural light beam 210 emitted from the LED element 201, and the reflected light is reflected by a reflective sheet 205 provided on one (lower) surface of the light guide 203, so that the reflected light beam is directed again toward the liquid crystal display panel 11. A λ / 4 plate, which is a retardation plate 216, is provided between the reflective sheet 205 and the light guide 203, or between the light guide 203 and the reflective polarizing plate 49, and the reflected light beam is reflected by the reflective sheet 205 and passes through twice, thereby converting the reflected light beam from P polarized light to S polarized light, thereby improving the efficiency of use of the light source light as image light. As shown by arrow 213 in Figure 8, the image light beam, the light intensity of which is modulated by the video signal in the liquid crystal display panel 11, enters the retroreflective member 2 in Figure 1, and after reflection, passes through the window glass 105 to obtain a real image, a floating image 3, inside or outside the store space.

[0101] 9, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (lower surface) of the liquid crystal display panel 11 facing the light source device 13, and selectively reflects one side polarized wave (e.g., S wave) 211 of the natural light beam 210 emitted from the LED element 201, and the reflected light beam is reflected by a reflective sheet 205 provided on one (lower) surface of the light guide 203, so that the reflected light beam is directed again toward the liquid crystal display panel 11. A λ / 4 plate, which is a retardation plate 216, is provided between the reflective sheet 205 and the light guide 203, or between the light guide 203 and the reflective polarizing plate 49, and the reflected light beam is reflected by the reflective sheet 205 and passes through twice, thereby converting the reflected light beam from S polarized light to P polarized light, thereby improving the efficiency of use of the light source light as image light. As shown by arrow 214 in Figure 9, the image light beam whose light intensity has been modulated by the image signal in the liquid crystal display panel 11 enters the retroreflective member 2 in Figure 1, and after reflection, passes through the window glass 105 to obtain a real image, a floating image 3, inside or outside the store space.

[0102] In the light source device 13 shown in Fig. 8 and Fig. 9, the reflective polarizer 49 provided on the light incident surface of the opposing liquid crystal display panel 11 acts to reflect the polarized light component on one side, and the theoretically obtainable contrast ratio is the product of the inverse of the cross transmittance of the reflective polarizer 49 and the inverse of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel 11. This provides high contrast performance. In fact, it was confirmed by experiments that the contrast performance of the displayed image was improved by 10 times or more. As a result, a high-quality image comparable to that of a self-luminous organic EL was obtained.

[0103] <Example of image display device (2)> Fig. 10 shows another example of a specific configuration of the image display device 1. The light source device 13 in Fig. 10 has the same configuration as the light source device in Fig. 12 described later. This light source device 13 is configured by housing an LED, a collimator, a composite diffusion block, a light guide, and the like in a case made of, for example, plastic, and has a liquid crystal display panel 11 attached to the upper surface. In addition, an LED element 14, which is a semiconductor light source shown in Figs. 12 and 13, and an LED board 102 on which a control circuit for the LED element 14 is mounted are attached to one side of the case of the light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED element 14 and the control circuit, is attached to the outer surface of the LED board 102.

[0104] The liquid crystal display panel frame attached to the top surface of the case is configured to have a liquid crystal display panel 11 attached to the liquid crystal display panel frame, and further, an FPC 403 electrically connected to the liquid crystal display panel 11, etc. attached to it. That is, the liquid crystal display panel 11, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light together with the LED elements 14, which are solid-state light sources, based on a control signal from a control circuit (not shown) that constitutes the electronic device.

[0105] <Example of image display device (3)> Next, another example of a specific configuration of the image display device 1 will be described with reference to Fig. 11. The light source device of this image display device 1 converts a divergent light beam of natural light, which is a mixture of P-polarized waves and S-polarized waves, emitted from an LED element 14 (e.g., LED element 14a) into a substantially parallel light beam by an LED collimator lens 18, and reflects the parallel light toward the liquid crystal display panel 11 by a reflective light guide 304. The reflected light is incident on a wave plate and a reflective polarizing plate 49 arranged between the liquid crystal display panel 11 and the reflective light guide 304. A specific polarized wave (e.g., S-polarized wave) is reflected by the reflective polarizing plate 49, the phase of which is converted by the wave plate, the light returns to the reflecting surface, passes through the retardation plate 216 again, and is converted into a polarized wave (e.g., P-polarized wave) that transmits through the reflective polarizing plate 49.

[0106] As a result, the natural light from the LED elements 14 is aligned to a specific polarization (e.g., P polarization), enters the liquid crystal display panel 11, and is luminance-modulated according to the video signal to display an image on the panel surface. As in the above example, FIG. 11 shows a plurality of LED elements 14 (for example, only one LED element 14a because it is a vertical cross section) that constitute the light source, and these are attached at a predetermined position relative to the LED collimator lens 18. Each of the LED collimator lenses 18 is formed of a light-transmitting resin such as acrylic or glass. As in the above example, the LED collimator lens 18 has an outer peripheral surface of a cone convex shape obtained by rotating a parabolic cross section, and at the top of the lens, a concave portion is formed at the center of the convex portion (i.e., a convex lens surface). Also, the center of the flat portion has a convex lens surface that protrudes outward (or may be a concave lens surface that is recessed inward). The paraboloid that forms the conical outer peripheral surface of the LED collimator lens 18 is set within an angle range that allows the light emitted from the LED element 14 in the side direction to be totally reflected therein, or a reflective surface is formed.

[0107] The above configuration is the same as that of the light source device of the image display device shown in Fig. 12, Fig. 13, etc. Furthermore, the light converted into approximately parallel light by the LED collimator lens 18 shown in Fig. 11 is reflected by the reflective light guide 304, and a specific polarized light is transmitted by the action of the reflective polarizing plate 49, while the other polarized light is transmitted through the reflective light guide 304 again and reflected by the reflector 271 provided on the surface of the reflective light guide 304 opposite to the liquid crystal display panel 11. At this time, the light is polarized and converted by passing twice through the λ / 4 plate, which is the retardation plate 270 arranged between the reflector 271 and the reflective light guide 304, and is transmitted through the light guide 304 again and the reflective polarizing plate 49 provided on the opposite side, i.e., the liquid crystal display panel 11 side, and is made incident on the liquid crystal display panel 11 with the polarization direction aligned. As a result, all the light from the light source can be utilized, and the light utilization efficiency is doubled.

[0108] In a conventional TV set, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in both the horizontal direction of the screen (shown by the X-axis in FIG. 16A) and the vertical direction of the screen (shown by the Y-axis in FIG. 16B). In contrast, the diffusion characteristics of the light flux emitted from the liquid crystal display panel 11 of this embodiment are 1 / 5 of the conventional 62 degrees when the viewing angle at which the luminance is 50% of that when viewed from the front (angle 0 degrees) is set to 13 degrees, as shown in example 1 of FIG. 16. Similarly, the vertical viewing angle is made uneven between the top and bottom, and the reflection angle and the area of ​​the reflection surface of the reflective light guide are optimized to suppress the upper viewing angle to about 1 / 3 of the lower viewing angle. As a result, the amount of image light heading in the viewing direction is significantly improved compared to conventional liquid crystal TVs, and the luminance is 50 times or more higher.

[0109] Furthermore, assuming the viewing angle characteristics shown in Example 2 of FIG. 16, the viewing angle at which the luminance is 50% of that when viewed from the front (angle 0 degrees) is set to 5 degrees, which is 1 / 12 of the conventional 62 degrees. Similarly, the vertical viewing angle is equal from top to bottom, and the reflection angle and the area of ​​the reflection surface of the reflective light guide are optimized to suppress the viewing angle to about 1 / 12 of the conventional viewing angle. As a result, the amount of image light heading in the viewing direction is significantly improved compared to conventional liquid crystal TVs, and the luminance is 100 times or more. As described above, by making the viewing angle narrow, the amount of light flux heading in the viewing direction can be concentrated, and the light utilization efficiency is significantly improved. As a result, even if a liquid crystal display panel for a conventional TV is used, a significant improvement in luminance can be achieved with the same power consumption by controlling the light diffusion characteristics of the light source device, and the image display device 1 can be made compatible with a space floating image display device for outdoor use.

[0110] Returning to Fig. 11, the basic configuration is as follows: a light beam with narrow-angle directional characteristics is incident on a liquid crystal display panel 11 by a light source device, and the image information displayed on the screen of the liquid crystal display panel 11 is luminance-modulated according to a video signal, and then reflected by a retroreflective member 2, and the resulting floating-in-space image 3 is displayed outdoors or indoors through the window glass 105 in Fig. 1.

[0111] <Example of light source device 13 (1)> Next, a detailed configuration example of the optical system including the light source device 13 and the like housed in the housing 106 of FIG. 6B will be described in detail with reference to FIGS. 13(A) and (B) as well as FIG.

[0112] FIG. 12 shows LED elements 14 (14a, 14b) constituting the light source, which are attached at a predetermined position relative to the LED collimator 15. Each of the LED collimators 15 is formed of a light-transmitting resin such as acrylic. As shown in FIG. 13(B), the LED collimator 15 has a cone-shaped outer peripheral surface 156 obtained by rotating a parabolic cross section, and has a concave portion 153 at the top of the convex portion (i.e., a convex lens surface) 157 formed at the center. The central portion of the flat portion has a convex lens surface 154 protruding outward (or a concave lens surface recessed inward). The parabolic surface forming the cone-shaped outer peripheral surface 156 of the LED collimator 15 is set within an angle range that allows the light emitted from the LED elements 14 in the peripheral direction to be totally reflected therein, or a reflective surface is formed thereon.

[0113] The LED elements 14 are disposed at predetermined positions on the surface of the LED substrate 102, which is the circuit substrate. The LED substrate 102 is disposed and fixed to the LED collimator 15 such that the LED elements 14 (14a, 14b) on the surface are positioned at the center of the recess 153.

[0114] According to this configuration, the light emitted from the LED elements 14 by the above-mentioned LED collimator 15, particularly the light emitted from the central portion upward (to the right in FIG. 13(B)), is collected and made parallel by the two convex lens surfaces 157, 154 forming the outer shape of the LED collimator 15. The light emitted from the other portions toward the periphery is reflected by the parabolic surface forming the conical outer circumferential surface 156 of the LED collimator 15, and is similarly collected and made parallel. In other words, the LED collimator 15 having a convex lens in its central portion and a parabolic surface formed on its peripheral portion makes it possible to extract almost all of the light generated by the LED elements 14 (14a, 14b) as parallel light, thereby improving the utilization efficiency of the generated light.

[0115] 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 is configured by combining a columnar translucent member having a parallelogram cross section (hereinafter, parallelogram column) and a columnar translucent member having a triangular cross section (hereinafter, triangular column), and arranging them in an array in parallel to a plane perpendicular to the optical axis of the parallel light from the LED collimator 15. Furthermore, a polarizing beam splitter (hereinafter, "PBS film") 211 and a reflective film 212 are alternately provided at the interface between adjacent translucent members arranged in the 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.

[0116] 13(A) is provided on the exit surface of this polarization conversion element 21. That is, the light emitted from the LED elements 14 is converted into parallel light by the action of the LED collimator 15, enters the synthetic diffusion block 16, is diffused by the texture 161 on the exit side, and then reaches the light guide 17.

[0117] As shown in Fig. 13(B), the light guide 17 is a rod-shaped member having a substantially triangular cross section, which is made of a light-transmitting resin such as acrylic. As is clear from Fig. 12, the light guide 17 includes a light guide light incident portion (including a light guide light incident surface) 171 which faces the exit surface of the synthetic diffusion block 16 via a first diffusion plate 18a, a light guide light reflecting portion (including a light guide light reflecting surface) 172 which forms an inclined surface, and a light guide light exit portion (including a light guide light exit surface) 173 which faces the liquid crystal display panel 11, which is a liquid crystal display element, via a second diffusion plate 18b.

[0118] 12 and a partially enlarged view of Fig. 13(B), a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape in the light guide light reflecting portion 172 of the light guide 17. The reflective surfaces 172a (the line segments slanting upward to the right in Fig. 13(B)) form an angle αn (n is a natural number, which is 1 to 130 in this example) with respect to the horizontal plane shown by the dashed line in the figure, and as an example, αn is set to 43 degrees or less (but 0 degrees or more) here.

[0119] The light guide entrance portion 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the exit surface of the synthetic diffusion block 16 is diffused and enters through the first diffusion plate 18a, and as is clear from Fig. 12, the parallel light is bent (deflected) slightly upward by the light guide entrance portion 171 and reaches the light guide light reflection portion 172, where it is reflected and reaches the liquid crystal display panel 11 provided on the exit surface at the top of Fig. 12.

[0120] According to the image display device 1 described above in detail, the light utilization efficiency and the uniform illumination characteristics are further improved, and it is possible to manufacture the modularized S-polarized light source device in a small size and at low cost. 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 to this, and the same action and effect can be obtained by providing the polarization conversion element 21 in the optical path leading to the liquid crystal display panel 11.

[0121] As described above, the light guide light reflection section 172 has a large number of reflection surfaces 172a and connection surfaces 172b formed alternately in a sawtooth shape, and the illumination light beam is totally reflected on each reflection surface 172a and directed upward, and then enters the light direction conversion panel 54, which is provided with a narrow-angle diffusion plate (not shown) in the light guide light exit section 173 and controls the directional characteristics as a substantially parallel diffused light beam, and then enters 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 section 173 and the liquid crystal display panel 11, but the same effect can be obtained by providing the light direction conversion panel 54 on the exit surface of the liquid crystal display panel 11.

[0122] <Example of light source device 13 (2)> FIG. 14 shows another example of the configuration of the optical system of the light source device 13 and the like. In FIG. 14, similar to the example of FIG. 13, a plurality of (two in this example) LED elements 14 (14a, 14b) constituting the light source are shown, and these are attached at a predetermined position relative to the LED collimator 15. Each of the LED collimators 15 is formed of a light-transmitting resin such as acrylic. Similarly to the example of FIG. 13, the LED collimator 15 has a cone-shaped outer peripheral surface 156 obtained by rotating a parabolic cross section, and at the top of the LED collimator 15, a concave portion 153 having a convex portion (i.e., a convex lens surface) 157 formed in the center thereof is formed. Also, at the center of the flat portion, a convex lens surface 154 protruding outward (or a concave lens surface recessed inward) is formed. The parabolic surface forming the cone-shaped outer peripheral surface 156 of the LED collimator 15 is set within an angle range in which the light emitted from the LED elements 14 in the peripheral direction can be totally reflected therein, or a reflective surface is formed thereon.

[0123] The LED elements 14 (14a, 14b) are disposed at predetermined positions on the surface of the LED substrate 102, which is the circuit substrate. The LED substrate 102 is disposed and fixed to the LED collimator 15 such that the LED elements 14 (14a, 14b) on the surface are positioned at the center of the recess 153.

[0124] According to this configuration, the light emitted from the LED element 14 by the above-mentioned LED collimator 15, particularly the light emitted from the central portion upward (to the right in FIG. 14), is collected and made parallel by the two convex lens surfaces 157, 154 forming the outer shape of the LED collimator 15. The light emitted from the other portions toward the periphery is reflected by the parabolic surface forming the conical outer circumferential surface 156 of the LED collimator 15, and is similarly collected and made parallel. In other words, the LED collimator 15 having a convex lens in its central portion and a parabolic surface formed on its peripheral portion makes it possible to extract substantially all of the light generated by the LED element 14 as parallel light, and improves the utilization efficiency of the generated light.

[0125] As shown in Fig. 14(A), 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 having a substantially triangular cross section by a light-transmitting resin such as acrylic. As is clear from Fig. 14(A), the light guide 170 includes a light guide entrance portion (including an entrance surface) 171 of the light guide 170 that faces the emission surface of the synthetic diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (including a light guide light reflection surface) 172 that forms an inclined surface, and a light guide light emission portion (including a light guide light emission surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via a reflective polarizing plate 200.

[0126] If this reflective polarizing plate 200 is selected to have the property of reflecting P polarized light and transmitting S polarized light, it will reflect the P polarized light of the natural light emitted from the LED element 14 which is the light source, pass through the λ / 4 plate 172c provided in the light guide light reflecting portion 172 shown in Figure 14(B), be reflected by the reflecting surface 172d, and pass again through the λ / 4 plate 172c to be converted into S polarized light, and all the light beams entering the liquid crystal display panel 11 will be unified into S polarized light.

[0127] Similarly, if a material having the property of reflecting S-polarized light and transmitting P-polarized light is selected as reflective polarizing plate 200, it will reflect the S-polarized light in the natural light emitted from LED element 14, which is the light source, pass through λ / 4 plate 172c provided in light guide light reflecting section 172 shown in Fig. 14(B), be reflected by reflecting surface 172d, and pass through λ / 4 plate 172c again to be converted into P-polarized light, and all the light beams entering liquid crystal display panel 52 will be unified into P-polarized light. With the above-mentioned configuration, polarization conversion can also be achieved.

[0128] <Example of light source device 13 (3)> Another example of the configuration of the optical system of the light source device or the like will be described with reference to Fig. 11. In the third example, as shown in Fig. 11, a divergent light beam of natural light, which is a mixture of P-polarized light and S-polarized light, emitted from an LED substrate 102 is converted into a substantially parallel light beam by an LED collimator lens 18, and is reflected toward a liquid crystal display panel 11 by a reflective light guide 304. The reflected light is incident on a reflective polarizing plate 206 disposed between the liquid crystal display panel 11 and the reflective light guide 304. A specific polarized wave (e.g., S-polarized wave) is reflected by the reflective polarizing plate 206, transmitted through a surface connecting the reflective surfaces of the light guide 304, reflected by a reflector 271 disposed facing the opposite surface of the light guide 304, and polarized and converted by transmitting twice through a phase plate (λ / 4 wave plate) 270, transmitted through the light guide and the reflective polarizing plate, and incident on the liquid crystal display panel 11, where it is modulated into image light. At this time, by combining a specific polarized wave with the polarization-converted polarization plane, the light utilization efficiency becomes twice as high as usual, and the degree of polarization (extinction ratio) of the reflective polarizing plate is also included in 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.

[0129] As a result, the natural light from the LED is aligned to a specific polarization (for example, P polarization). In FIG. 11, as in the above example, a plurality of LED elements 14 (only one is shown because it is a vertical cross section) constituting the light source are provided, and these are attached at a predetermined position relative to the LED collimator lens 18. Each of the LED collimator lenses 18 is formed of a light-transmitting resin or glass, such as acrylic. As in the above example, the LED collimator lens 18 has a convex outer peripheral surface obtained by rotating a parabolic cross section, and at the top of the lens, a concave portion having a convex portion (i.e., a convex lens surface) formed in the center is formed. Also, the center of the flat portion has a convex lens surface protruding outward (or may be a concave lens surface recessed inward). The parabolic surface forming the conical outer peripheral surface of the LED collimator lens 18 is set within an angle range in which the light emitted from the LED collimator lens 18 in the peripheral direction can be totally reflected inside the lens, or a reflective surface is formed.

[0130] The LED elements 14 are arranged at predetermined positions on the surface of the circuit board, an LED board 102. The LED board 102 is fixed to the LED collimator lens 18 such that the LEDs on the surface are located at the center of the recess.

[0131] According to this configuration, the light emitted from the LED element 14, particularly the light emitted from the central portion, is collected by the two convex lens surfaces that form the outer shape of the LED collimator lens 18 to become parallel light. The light emitted from the other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the cone shape of the LED collimator lens 18, and is similarly collected to become parallel light. In other words, the LED collimator lens 18, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract substantially all of the light generated by the LED element 14 as parallel light, thereby improving the utilization efficiency of the generated light.

[0132] <Example of light source device 13 (4)> Further, another example of the configuration of the optical system of the light source device, etc., will be described with reference to FIG. 17. Two optical sheets 207 that convert the diffusion characteristics in the vertical and horizontal directions of the drawing are used on the light emission side of the LED collimator lens 18, and the light from the LED collimator lens 18 is made to enter between the two optical sheets 207 (also called diffusion sheets or diffusion films). When the optical sheet 207 is configured with one sheet, the vertical and horizontal diffusion characteristics are controlled by the fine shapes of the front and back surfaces. In addition, a plurality of optical sheets 207 may be used to share the function. Depending on the front and back shapes of the optical sheet 207, the diffusion angle of the light from the LED collimator lens 18 in the vertical direction of the screen is matched to the width of the vertical surface of the reflecting surface of the optical sheet 207, and in the horizontal direction, the number of LED elements 14 and the divergence angle from the optical element 107 are optimally designed as design parameters so that the surface density of the light flux emitted from the liquid crystal display panel 11 is uniform. That is, in this embodiment, the diffusion characteristics are controlled by the surface shapes of a plurality of diffusion sheets instead of the light guide. In this embodiment, the polarization conversion is performed in the same manner as in the above-described light source device example 3. Furthermore, a polarization conversion element may be provided between the LED collimator lens 18 and the optical sheet 207, and the light source light may be made incident on the optical sheet 207 after the polarization conversion is performed.

[0133] If the above-mentioned reflective polarizing plate 206 is selected to have the property of reflecting S-polarized light and transmitting P-polarized light, it will reflect the S-polarized light in the natural light emitted from the LED element serving as the light source, pass through retardation plate 270, be reflected by reflective surface 272, and be converted into P-polarized light by passing through retardation plate 270 again, and then enter liquid crystal display panel 11. The optimum value for the thickness of this retardation plate 270 must be selected depending on the angle of incidence of the light beam on the retardation plate, and the optimum value is in the range of λ / 16 to λ / 4.

[0134] <Example of 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 disposed on the light emission side of the LED collimator lens 18. Natural light from the LED element 14 (e.g., LED element 14c) is aligned to a specific polarization and incident on an optical element 81 that controls the diffusion characteristics, and the diffusion characteristics in the vertical and horizontal directions of the drawing are controlled to optimize the light distribution characteristics toward the reflection surface of the reflective light guide 220. As shown in FIG. 18(B), a concave-convex pattern 222 is provided on the surface of the reflective light guide 220, and the light is reflected toward an image display device (not shown) disposed on the opposing surface of the reflective light guide 220, thereby obtaining the desired diffusion characteristics. The positioning accuracy of the LED element 14 of the light source and the LED collimator lens 18 greatly affects the efficiency of the light source, so that the optical axis accuracy of about 50 μm is usually required. Therefore, as a countermeasure to the reduction in installation accuracy due to the expansion of the LED collimator lens 18 caused by heat generation from the LEDs, the inventors have mitigated the reduction in installation accuracy by using multiple or a single unit in the light source device as a light source unit 223 structure that integrates several LED elements 14 and the LED collimator lens 18.

[0135] In the embodiment shown in Fig. 18(A), (B), and (C), a plurality of light source units 223 each integrating an LED element 14 and an LED collimator lens 18 are incorporated at both ends of the long side direction of the reflective light guide 220 (three on each side in the embodiment of Fig. 18), realizing uniform brightness of the light source device. A plurality of uneven patterns 222 approximately parallel to the light source units are formed on the reflecting surface 220a of the light guide 220, and the surface of each uneven pattern 222 is also formed as a polyhedron, so that the amount of light incident on the image display device can be controlled with high precision. In this embodiment, the shape of the reflecting surface is described as the uneven pattern 222, but a pattern in which triangular surfaces, wave surfaces, etc. are regularly or irregularly arranged may be used, and the light distribution pattern from the light guide 220 toward the image display device may be controlled by the surface shape. In addition, a light-shielding wall 224 is provided on the side of the light guide 220 to prevent the light controlled by the LED collimator lens 18 from leaking out of the light source device 13, and the LED element 14 is designed with a metal base 225 to enhance heat dissipation.

[0136] <Lenticular sheet> The following describes the action of the lenticular lens that controls the diffusion characteristics of the light emitted from the image display device 1. By optimizing the lens shape of the lenticular lens, the light emitted from the image display device 1 is transmitted through or reflected by the window glass 105, and the space floating image 3 can be obtained efficiently. That is, by combining two lenticular lenses or arranging a microlens array in a matrix to provide a sheet that controls the diffusion characteristics of the image light from the image display device 1, the brightness (relative brightness) of the image light can be controlled in the X-axis and Y-axis directions according to the reflection angle (vertical direction is 0 degrees). In this embodiment, such a lenticular lens can make the brightness characteristics in the vertical direction steeper than in the past, as shown in FIG. 16(B). Furthermore, by changing the balance of the directional characteristics in the up and down directions (positive and negative directions of the Y axis), the brightness (relative brightness) of the light due to reflection and diffusion can be increased. These effects make it possible to produce image light with a narrow diffusion angle (in other words, high directivity) and containing only specific polarization components, like the image light from a surface-emitting laser image source, thereby suppressing the ghost images that would occur in the retroreflective material when using image display devices using conventional technology, and controlling the spatially floating image produced by retroreflection to reach the viewer's eyes efficiently.

[0137] Furthermore, with each of the light source devices described above, it is possible to realize directional characteristics that are significantly narrower in both the X-axis and Y-axis directions than the diffusion characteristics of emitted light from a general liquid crystal display panel shown in Figures 16(A) and (B) (shown as "conventional" in the figures). This makes it possible to realize 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.

[0138] Fig. 15 shows an example of the characteristics of the lenticular lens employed in this embodiment. This example particularly shows the characteristics on the X-axis (vertical direction), and characteristic O shows a luminance characteristic that is symmetrical up and down, with the peak of the light emission direction at an angle of about 30 degrees upward from the vertical direction (0 degrees). Furthermore, characteristic A and characteristic B show examples of characteristics in which the image light above the peak luminance is further concentrated at about 30 degrees to increase the luminance (relative luminance). For this reason, in characteristic A and characteristic B, the luminance (relative luminance) of light is rapidly reduced at angles exceeding 30 degrees, compared to characteristic O.

[0139] That is, according to the optical system including the above-mentioned lenticular lens, when the image light beam from the image display device 1 is incident on the retroreflective member 2, the emission angle and viewing angle of the image light aligned to a narrow angle by the light source device 13, 230 can be controlled, and the degree of freedom of installation of the retroreflective member 2 can be significantly improved. As a result, the degree of freedom of the relationship of the image formation position of the space floating image 3 that is reflected or transmitted through the window glass 105 in FIG. 1 and formed at a desired position can be significantly improved. As a result, it is possible to efficiently reach the eyes of the viewer outdoors or indoors as light with a narrow diffusion angle (high straightness) and only a specific polarization component. According to this, even if the intensity (brightness) of the image light from the image display device 1 is reduced, the viewer can accurately recognize the image light and obtain information. In other words, by reducing the output of the image display device 1, a space floating image display device with low power consumption can be realized.

[0140] Although various embodiments have been described above in detail, the present invention is not limited to the above-described embodiments and includes various modified examples. For example, the above-described embodiments are detailed descriptions of the entire system in order to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0141] In the technology according to the present embodiment, the floating image is displayed as high-resolution and high-brightness image information in a floating state, which allows the user to operate the device without worrying about contact infection. If the technology according to the present embodiment is used in a system used by an unspecified number of users, it is possible to reduce the risk of contact infection and provide a non-contact user interface that can be used without worry. This contributes to "3. Health and well-being for all" of the Sustainable Development Goals (SDGs) proposed by the United Nations. In addition, the technology according to the present embodiment makes it possible to efficiently reflect only the normal reflected light on the retroreflective material by reducing the divergence angle of the emitted image light and aligning it to a specific polarization, thereby making it possible to obtain a bright and clear floating image with high light utilization efficiency. According to the technology according to the present embodiment, it is possible to provide a highly usable non-contact user interface that can significantly reduce power consumption. This contributes to "9. Build resilient infrastructure, promote inclusive and sustainable development" of the Sustainable Development Goals (SDGs) proposed by the United Nations. [Explanation of symbols]

[0142] 1: image display device, 2: retroreflective member, 3: spatially floating image, 4: flat mirror, 5: input / output terminal, 11: liquid crystal display panel, 12: absorptive polarizer, 13: light source device, 21: λ / 4 plate, 100: transparent member, 101: beam splitter (polarized light separation member), 106: housing, 112: absorptive polarizer, 601: upper part of housing, 602: lower part of housing, 603: upper surface, 604: inclined surface, 605: window portion, 606: side, 607: side, 608: lower surface, 610: control board, 611: rechargeable battery.

Claims

1. A space floating image display device that forms a space floating image, A cylindrical housing having an upper housing portion and a lower housing portion; a window portion provided in a part of an upper portion of the housing, through which image light for forming the floating image in space passes; an image display device provided inside the upper portion of the housing, the image display device having a light source device and a display panel that generates and emits image light based on light from the light source device; A retroreflective member provided inside the upper part of the housing between the window portion and the image display device, which retroreflects image light from the image display device; A rechargeable battery is housed in the lower part of the housing. A floating image display device.

2. 2. The space floating image display device according to claim 1, A polarization separation member is provided inside the upper part of the housing, between the window portion and the image display device, and reflects the image light from the retroreflective member toward the window portion. A floating image display device.

3. 2. The space floating image display device according to claim 1, A control unit is provided in the lower part of the housing and has a control board. The control board is provided below the image display device. A floating image display device.

4. 2. The space floating image display device according to claim 1, A microphone is mounted on the housing, The control unit receives the sound input from the microphone, reads out and outputs the sound associated with the floating image in space, and performs processing corresponding to a predetermined instruction. A floating image display device.

5. 2. The space floating image display device according to claim 1, A speaker is mounted inside the housing, outputting a sound associated with the floating image to a user from the speaker; A floating image display device.

6. 3. The space floating image display device according to claim 2, a plane mirror arranged in a space connecting the image display device and the polarization separation member, the plane mirror reflecting the image light of a specific polarization from the image display device toward the polarization separation member; A floating image display device.

7. 2. The space floating image display device according to claim 1, An input / output terminal is provided on a side surface of the housing, Power is supplied from the outside to the rechargeable battery housed in the lower part of the housing via the input / output terminal. A floating image display device.

8. 2. The space floating image display device according to claim 1, An input / output terminal is provided on a side surface of the upper part of the housing, A signal is supplied from the outside to the image display device via the input / output terminal. A floating image display device.

9. 2. The space floating image display device according to claim 1, At least a portion of the cylindrical housing can be stored in a bottle holder in a vehicle. A floating image display device.

10. 2. The space floating image display device according to claim 1, A cover is provided on the outside of the window portion. A floating image display device.

Images