Space floating image display device

Abstract

To suitably display images to the outside a space, which contributes to "3 Ensure healthy lives and promote well-being for all at all ages," "9 Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation," and "11 Make cities and human settlements inclusive, safe, resilient, and sustainable" in sustainable development goals.SOLUTION: A space floating image display device comprises a display, a light source device, and a retroreflection plate. The light source device includes a light source, a substrate on which the light source is installed, a reflector that reflects light from the light source, a light guide that guides light from the reflector, a diffusion plate the diffuses light from the light guide, a second reflector that reflects part of the light reflected by the reflector, and a third reflector that reflects light reflected by the second reflector in a direction directed to the light guide. The diffusion plate is arranged in proximity to the display. The substrate is arranged at a position more distant than the reflector relative to the display.SELECTED DRAWING: Figure27B

Description

[Technical field]

[0001] The present invention relates to a space floating image information display system and a light source device used therein. [Background technology]

[0002] As a space-floating information display system, a video display device that displays an image directly to the outside and a display method that displays the image as a spatial screen are already known. In addition, a detection system that reduces false detections of operations on the operation surface of the displayed spatial image is also disclosed in, for example, Patent Document 1. [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] However, as a method for reducing false detections in response to manipulation of the spatial image or the above-mentioned conventional technology of the spatial floating image information display system, no consideration has been given to design optimization technology including the light source of the image display device that serves as the image source of the spatial floating image.

[0005] The object of the present invention is to provide a technology in a space-floating information display system or a space-floating image display device that is capable of displaying suitable images with high visibility (apparent resolution and contrast) and reduced false detections in response to operations on the displayed spatial image. [Means for solving the problem]

[0006] 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 given below. A space-floating image display device includes a display device that displays an image, a light source device that supplies light to the display device, and a retroreflector that reflects image light from the display device and displays a real space-floating image in the air using the reflected light. The light source device includes a light source, a substrate on which the light source is installed, a reflector that reflects light from the light source, a light guide that guides light from the reflector, a diffusion plate that diffuses light from the light guide, a second reflector that reflects a portion of the light reflected by the reflector, and a third reflector that reflects the light reflected by the second reflector in a direction toward the light guide. The diffusion plate is disposed close to the display device, and the substrate is disposed at a position farther away from the display device than the reflector. Effect of the Invention

[0007] According to the present invention, it is possible to realize a space-floating information display system or a space-floating image display device that can display space-floating image information in an appropriate manner and has a sensing function with few false detections. Other problems, configurations, and effects will be made clear by the following description of the embodiments. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image information display system according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing an example of a configuration of a main part and a configuration of a retroreflection part of a space floating image information display system according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a diagram showing another example of the configuration of the main components of the space floating image information display system according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing another example of the configuration of the main components of the space floating image information display system according to an embodiment of the present invention. [Diagram 5] FIG. 1 is an explanatory diagram for explaining the function of a sensing device used in the space floating image information display system. [Figure 6] FIG. 1 is an explanatory diagram of the principle of three-dimensional image display used in the space floating image information display system. [Figure 7] FIG. 1 is an explanatory diagram of a measurement system for evaluating the characteristics of a reflective polarizing plate. [Figure 8] FIG. 11 is a characteristic diagram showing the transmittance characteristics of the transmission axis of a reflective polarizing plate versus the light incidence angle. [Figure 9] FIG. 4 is a characteristic diagram showing transmittance characteristics with respect to the light incidence angle of the reflection axis of a reflective polarizing plate. [Figure 10] FIG. 11 is a characteristic diagram showing the transmittance characteristics of the transmission axis of a reflective polarizing plate versus the light incidence angle. [Figure 11] FIG. 4 is a characteristic diagram showing transmittance characteristics with respect to the light incidence angle of the reflection axis of a reflective polarizing plate. [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] 1 is a layout diagram showing a main part of a space floating image information display system according to an embodiment of the present invention; [Figure 16] 1 is a cross-sectional view showing a configuration of an image display device constituting a space floating image information display system according to an embodiment of the present invention; [Figure 17] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 18] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 19] FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 20] 1 is an explanatory diagram for explaining a light source diffusion characteristic of a video display device. [Figure 21] FIG. 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 22] FIG. 1 is an explanatory diagram for explaining the diffusion characteristics of a video display device. [Figure 23]1 is a cross-sectional view showing a configuration of an image display device that constitutes a space floating image information display system. [Figure 24] 1 is an explanatory diagram for explaining the principle of ghost images occurring in a conventional space floating image information display system; [Diagram 25] 1 is a cross-sectional view showing a configuration of an image display device constituting a space floating image information display system according to an embodiment of the present invention; [Figure 26] FIG. 13 is a diagram showing another example of a specific configuration of the light source device. [Figure 27A] FIG. 13 is a diagram showing another example of a specific configuration of the light source device. [Figure 27B] FIG. 11 is a cross-sectional view showing another example of a specific configuration of the light source device. [Figure 27C] FIG. 11 is a cross-sectional view showing another example of a specific configuration of the light source device. [Figure 27D] 11 is a diagram showing a part of another example of a specific configuration of a light source device. FIG. [Figure 28A] FIG. 13 is a diagram showing another example of a specific configuration of the light source device. [Figure 28B] FIG. 11 is a cross-sectional view showing another example of a specific configuration of the light source device. [Figure 29] FIG. 13 is a diagram showing another example of a specific configuration of the light source device. [Diagram 30] 11 is a cross-sectional view of an example of the shape of a diffusion plate in another example of a specific configuration of a light source device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 contents of the embodiments described below (hereinafter, also referred to as "the present disclosure"). The present invention also covers the spirit of the invention or the scope of the technical ideas described in the claims, or equivalents thereof. Furthermore, the configurations of the embodiments (examples) described below are merely examples, and various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed in this specification.

[0010] In addition, in the drawings for explaining the present invention, the same reference numerals are given to components having the same or similar functions, and different names are used as appropriate, while repeated explanations of functions, etc. may be omitted. In the following description of the embodiments, an image floating in space is expressed by the term "space-floating image". Instead of this term, it may be expressed as "aerial image", "spatial image", "floating image", "floating optical image of a displayed image", "floating optical image of a displayed image", etc. The term "floating image of a space" mainly used in the description of the embodiments is used as a representative example of these terms.

[0011] The present disclosure relates to an information display system capable of displaying an image generated by image light from a large-area image light source as a floating image inside or outside a store (space) by transmitting the image through a transparent member that divides the space, such as the glass of a show window. The present disclosure also relates to a large-scale digital signage system configured using a plurality of such information display systems.

[0012] According to the following embodiment, for example, it is possible to display high-resolution image information in a floating state on the glass surface of a show window or a light-transmitting plate. At this time, by making the divergence angle of the emitted image light small, i.e., an acute angle, and further aligning it with a specific polarization, it is possible to efficiently reflect only the normal reflected light to the retroreflective material. Therefore, the light utilization efficiency is high, and it is possible to suppress ghost images that occur in addition to the main floating image in space, which was a problem in the conventional retroreflective method, and to obtain a clear floating image in space.

[0013] In addition, a device including the light source of the present disclosure can provide a novel and highly usable space-floating image information display system that can significantly reduce power consumption. In addition, according to the technology of the present disclosure, a floating image information display system for a vehicle can be provided that can display a so-called unidirectional space-floating image that can be viewed from outside the vehicle through a shield glass including the front glass, rear glass, and side glass of the vehicle.

[0014] On the other hand, in the conventional space-floating image information display system, an organic EL panel or a liquid crystal display panel (liquid crystal panel or display panel) is combined with a retroreflective member 151 as a high-resolution color display image source 150. In the conventional space-floating image display device, the image light is diffused at a wide angle, so that in addition to the reflected light normally reflected by the retroreflective member 151 (see FIG. 23), ghost images (see symbols 301 and 302 in FIG. 23) are generated by the image light obliquely incident on the retroreflective member 2a as shown in FIG. 24, which impairs the image quality of the space-floating image. In addition, in the conventional space-floating image display device, as shown in FIG. 23, in addition to the normal space-floating image 300, a first ghost image 301, a second ghost image 302, and the like are generated multiple times. For this reason, the same space-floating image, which is a ghost image, can be viewed by people other than the viewer, which is a major problem from the viewpoint of security.

[0015] <First Configuration Example of the Space Floating Image Information Display System> FIG. 1(A) is a diagram showing an example of a usage form of the space-floating image information display system of the present disclosure. FIG. 1(A) is also a diagram explaining the overall configuration of the space-floating image information display system in this embodiment. Referring to FIG. 1(A), for example, in a store or the like, a space is divided by a show window (also called "window glass") 105 which is a translucent member such as glass. According to the space-floating information display system of the present disclosure (hereinafter also called "the system"), it is possible to display a floating image in one direction to the outside of the store (space) through such a transparent member.

[0016] Specifically, according to this system, light with narrow-angle directional characteristics and specific polarization is emitted as an image light beam from an image display device (display device) 1, enters a retroreflective member 2, is retroreflected and passes through a window glass 105, and forms a real aerial image 3 (space-floating image 3) outside the store. In Fig. 1(A), the inside of the transparent member (here, the window glass) 105 (inside the store) is shown as the depth direction, and the outside of the window glass 105 (for example, the sidewalk) is shown as the foreground.

[0017] On the other hand, it is also possible to provide the window glass 105 with a means for reflecting a specific polarized wave, and to reflect the image light beam by such means to form an aerial image at a desired position within the store.

[0018] 1(B) 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 that displays an original image of an aerial image, an image control unit that converts an input image to match the resolution of the panel, and an image signal receiving unit that receives a video signal.

[0019] Among these, the video signal receiving unit plays a role of handling wired input signals through an input interlace such as HDMI (High-Definition Multimedia Interface (registered trademark)) and wireless input signals such as Wi-Fi (registered trademark) (Wireless Fidelity). The video signal receiving unit can also function independently as a video receiving and displaying device. Furthermore, the video signal receiving unit can also display video information from a tablet, smartphone, etc. Furthermore, the video signal receiving unit can also be connected to a processor (arithmetic processing device) such as a stick PC as necessary, in which case the video signal receiving unit as a whole can be provided with capabilities such as calculation processing and video analysis processing.

[0020] Fig. 2 is a diagram showing an example of a main part configuration and a retroreflection part configuration of the space floating image information display system of the present disclosure. The configuration of the space floating image information display system will be described more specifically with reference to Fig. 2. As shown in Fig. 2(A), the system includes an image display device 1 that diverges image light of a specific polarization at a narrow angle in the oblique direction of a translucent plate (hereinafter referred to as a "transparent member") 100 having translucency such as glass. The image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having a narrow angle diffusion characteristic.

[0021] The image light of a specific polarization from the image display device 1 is reflected by a polarization separation member 101 (in the figure, the polarization separation member 101 is formed into a sheet shape and adhered to the transparent member 100) 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. A λ / 4 plate 21 is provided on the image light incident surface of the retroreflective member. The image light is polarized and converted from the specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, once when it enters the retroreflective member and once when it leaves.

[0022] Here, the polarization separation member 101, which selectively reflects image light of a specific polarization, has the property of transmitting polarized light of the other polarization after polarization conversion, so 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.

[0023] The light that forms 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 in a straight line even after passing through the optical image of the floating image 3. Therefore, the floating image 3 is an image with high directionality, unlike the diffuse image light formed on a screen by a general projector or the like.

[0024] 2, the floating image 3 is perceived as a bright image when viewed by a user from the direction of arrow A, but cannot be seen as an image at all when viewed by another person from the direction of arrow B. This characteristic is extremely suitable for use in a system that displays images that require high security or highly confidential images that should be concealed from people directly facing the user.

[0025] Depending on the performance of the retroreflective member 2, the polarization axis of the reflected image light may become misaligned. In this case, a portion of the image light with the misaligned polarization axis is reflected by the above-mentioned polarization separation member 101 and returns to the image display device 1. This portion of the image light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the image display device 1, and generates a ghost image, which may be a factor in causing a deterioration in the image quality of the spatial floating image.

[0026] Therefore, in this embodiment, an absorptive 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 emitted from the image display device 1 and absorbs the reflected light returning from the polarization separation member 101, thereby suppressing re-reflection. Therefore, according to this embodiment using the absorptive polarizing plate 12, it is possible to prevent or suppress degradation of image quality due to ghost images of spatially floating images.

[0027] 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.

[0028] 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. A light ray incident on the interior of the regularly arranged hexagonal prisms is reflected by the walls and bottom of the hexagonal prisms and is emitted as retroreflected light in a direction corresponding to the incident light, and a real image, a floating image in space, is displayed based on the image displayed on the image display device 1. The resolution of this floating image in space is largely dependent on the outer shape D and pitch P of the retroreflecting part of the retroreflecting member 2 shown in FIG. 2(B) as well as the resolution of the liquid crystal display panel 11. For example, when a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel is used, even if one pixel (one triplet) is about 80 μm, if the diameter D of the retroreflecting part is 240 μm and the pitch is 300 μm, one pixel of the floating image in space is equivalent to 300 μm. For this reason, the effective resolution of the floating image in space is reduced to about 1 / 3. Therefore, in order to make the resolution of the spatial floating image equal to that of the image display device 1, it is desirable to make the diameter and pitch of the retroreflective portion 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 material and the pixels of the liquid crystal display panel, it is preferable to design the pitch ratio of each to be a different integer multiple of one pixel. In addition, it is preferable to arrange the shape so that none of the sides of the retroreflective portion overlaps with any of the sides of one pixel of the liquid crystal display panel.

[0029] On the other hand, in order to manufacture retroreflective members at low cost, it is recommended to use a roll press method. Specifically, this is a method in which the retroreflective parts are aligned and shaped on a film, in which the inverse shape of the shape to be shaped is formed on the roll surface, an ultraviolet curing resin is applied onto a base material for fixing, and the film is passed between the rolls to form the required shape, and then the resin is irradiated with ultraviolet light to cure it, thereby obtaining the retroreflective member 2 of the desired shape.

[0030] <Second Configuration Example of the Space Floating Image Information Display System> FIG. 3 is a diagram showing another example of the main part configuration of the space floating image information display system according to an embodiment of the present invention. FIG. 3(A) is a diagram showing another embodiment of the space floating image information display system. The image display device 1 is configured with a liquid crystal display panel 11 as an image display element 11 and a light source device 13 that generates light of a specific polarized wave having a narrow angle diffusion characteristic. The liquid crystal display panel 11 is configured with a liquid crystal display panel having a screen size ranging from a small one having a screen size of about 5 inches to a large one having a screen size of more than 80 inches. For example, a polarization separation member 101 such as a reflective polarizing plate reflects the image light from the liquid crystal display panel toward a retroreflective member (retroreflective portion or retroreflective plate) 2.

[0031] The difference between the example shown in FIG. 3 and the example shown in FIG. 2 is that the reflective sheet is provided along the convex shape. Therefore, the image light from the liquid crystal display panel 11 is diffused according to the concave shape and enters the retroreflective member 2. As a result, a real image, a floating image 3, which is a real image that spreads and is enlarged from the screen display surface (display size is L1 in the figure) of the liquid crystal display panel 11 can be obtained. Furthermore, the image light beam reflected by the retroreflective member 2 is polarized and converted, and then passes through the convex reflective sheet, and is further diffused by the action of the concave shape provided on the other side of the convex surface, and passes through the transparent member 100, becoming a floating image L2 enlarged in the diagonal direction of FIG. 3(A). At this time, the magnification M of the floating image in space is M=L2 / L1.

[0032] As described above, an optical member having a lens effect is provided between the image display element 11 and the retroreflective member 2, or between the retroreflective member 2 and the floating image in space, and in some cases, this optical member is decentered or tilted from the optical axis connecting the image display device and the retroreflective member, so that the size and imaging position of the floating image in space obtained in the image information system can be set arbitrarily with respect to the optical axis. As described above, if the size and imaging position of the floating image in space are changed by the optical member, distortion occurs in the spatial image as it is, but by projecting an image with this distortion corrected on the image display device, a distortion-free image can be obtained in the entire image information system.

[0033] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2, and the incident image light is reflected by the retroreflective member 2 and then passes through the λ / 4 plate 21 again, whereby the polarization of the image light is converted and the image light passes through the convex polarization separation member 101. As a result, a floating image of a different size from the size displayed on the liquid crystal display panel can be formed at the position where it passes through the transparent member 100.

[0034] <Third Configuration Example of the Space Floating Image Information Display System> FIG. 3(B) is a diagram showing another example of a space-floating image information display system. As in FIG. 3(A), the image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarized wave having a narrow-angle diffusion characteristic. The liquid crystal display panel 11 can be configured from a small one with a screen size of about 5 inches to a large one exceeding 80 inches. For example, a polarization separation member 101 that selectively reflects image light of a specific polarized wave such as a reflective polarizing plate reflects the image light from the liquid crystal display panel 11 toward a retroreflection member (retroreflection portion or retroreflection plate) 2. The difference from the example in FIG. 2 is that the obtained space-floating image is enlarged as a virtual image X by a concave mirror 5. The configurations of the image display device 1 and the retroreflection member 2 are the same as those of the embodiment shown in FIG. 2 and FIG. 3(A), and the description will be omitted. In the configuration of FIG. 3(B), the polarization separation member 101 may further be made to have a convex shape.

[0035] Here, as described in FIG. 2, the floating image 3 is formed by light rays having high directivity, so when viewed from the direction of the arrow A, the floating image 3 is viewed as a bright image, but when viewed from the direction of the arrow B, the floating image 3 is not viewed as an image at all. Therefore, in the configuration of FIG. 3(B), when the user views from the direction of the arrow B, the floating image 3 is located behind the virtual image X, but the user does not view the floating image 3 at all, and only the virtual image X is viewed appropriately. Therefore, by utilizing this characteristic, if the floating image 3 is configured to be located behind the virtual image X as shown in FIG. 3(B), the entire system can be made smaller than if the floating image 3 is configured to be excluded from the viewing range of the user X when viewing the virtual image X, which is preferable.

[0036] <Fourth Configuration Example of the Space Floating Image Information Display System> FIG. 4 is a diagram showing another example of the main part configuration of the space floating image information display system according to an embodiment of the present invention. As in FIG. 3(A) and the like, the image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarized wave having a narrow-angle diffusion characteristic. For example, the liquid crystal display panel 11 is composed of a liquid crystal display panel having a screen size ranging from a small one having a screen size of about 5 inches to a large one having a screen size of more than 80 inches. The folding mirror 22 has a transparent member 100 as a substrate. A polarization separation member 101 that selectively reflects image light of a specific polarized wave, such as a reflective polarizing plate, is provided on the surface of the transparent member 100 on the image display device 1 side, and reflects the image light from the liquid crystal display panel 11 toward the retroreflection unit 2. This allows the folding mirror 22 to function as a mirror. The image light of a specific polarized wave from the image display device 1 is reflected by the polarization separation member 101 (in the illustrated example, a sheet-shaped polarization separation member 101 is attached to the transparent member 100 using an adhesive) provided on the lower surface of the transparent member 100, and enters the retroreflection member 2. Instead of the polarization separation member 101, an optical film having polarization separation properties may be vapor-deposited on the surface of the transparent member 100.

[0037] A λ / 4 plate 21 is provided on the light incidence surface of the retroreflective member 2, and the image light is polarized and converted by passing through it twice, converting a specific polarized wave into the other polarized wave with a phase difference of 90°. As a result, the retroreflected image light is transmitted through the polarization separation member 101, and a real image, a floating-in-space image 3, is displayed on the outside of the transparent member 100. Here, since the polarization axis becomes uneven due to retroreflection in the above-mentioned polarization separation member 101, a part of the image light is reflected and returns 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 a ghost image and significantly degrading the image quality of the floating-in-space image.

[0038] Therefore, in this embodiment, an absorptive polarizing plate 12 is provided on the image display surface of the image display device 1. This absorptive polarizing plate 12 transmits the image light emitted from the image display device 1 and absorbs the reflected light from the above-mentioned polarization separation member 101, and this configuration prevents image quality degradation due to ghost images of spatially floating images. Also, in order to reduce image quality degradation due to sunlight or illumination light outside the set, it is preferable to provide an absorptive polarizing plate 102 on the surface of the transparent member 105 on the image light output side.

[0039] Next, in order to sense the distance and positional relationship between the object and the sensor 44 for the space-floating image obtained by the space-floating image information system described above, sensors 44 with TOF (Time of Fly) function are arranged in multiple layers as shown in FIG. 5, and it becomes possible to sense not only the coordinates of the object in the planar direction, but also the coordinates in the depth direction and the moving direction and moving speed of the object.

[0040] To read two-dimensional distance and position, multiple combinations of infrared or ultraviolet invisible light emitters and receivers are arranged in a straight line, light from the emitters is shone on the object, and the reflected light is received by the receiver. The distance to the object is determined by the product of the difference between the time the light is emitted and the time it is received and the speed of light. In addition, coordinates on a plane can be read from the coordinates of the part where the difference between the time the light is emitted and the time it is received is the smallest, using multiple emitters and receivers. As described above, by combining the coordinates of an object on a plane (two dimensions) with multiple sensors as mentioned above, three-dimensional coordinate information can also be obtained.

[0041] Furthermore, a method for obtaining a three-dimensional space-floating image as the space-floating image information system described above will be described with reference to FIG. 6. FIG. 6 is a diagram for explaining the principle of three-dimensional image display used in the space-floating image information display system. A horizontal lenticular lens is arranged in accordance with the pixels of the image display screen of the liquid crystal display panel 11 of the image display device 1 shown in FIG. 4. As a result, in order to display motion parallax from three directions, P1, P2, and P3 in the horizontal direction of the screen as shown in FIG. 6, images from the three directions are treated as one block for every three pixels, image information from the three directions is displayed for each pixel, and the light emission direction is adjusted by the action of the corresponding lenticular lens (shown by vertical lines in FIG. 6) to separate and emit the light in three directions. As a result, a three-parallax stereoscopic image can be displayed.

[0042] <Reflective polarizing plate> In the space floating image information device of this embodiment, the polarization separation member 101 is used to improve the contrast performance, which determines the image quality, more than a general half mirror. The characteristics of a reflective polarizing plate will be described as an example of the polarization separation member 101 of this embodiment. FIG. 7 is an explanatory diagram of a measurement system for evaluating the characteristics of a reflective polarizing plate. The transmission characteristics and reflection characteristics of the reflective polarizing plate in FIG. 7 with respect to the incident angle of a light beam from a direction perpendicular to the polarization axis of the reflective polarizing plate are shown in FIGS. 8 and 9 as V-AOI. Similarly, the transmission characteristics and reflection characteristics of the reflective polarizing plate with respect to the incident angle of a light beam from a direction horizontal to the polarization axis of the reflective polarizing plate are shown in FIGS. 10 and 11 as H-AOI.

[0043] In the characteristic graphs of Figures 8 to 11 (each shown in color), the angle (deg) values ​​shown in the margins on the right side are shown from top to bottom in ascending order of the vertical axis, i.e., the transmittance (%). For example, in Figure 8, in the range of light with wavelengths of approximately 400 nm to 800 nm on the horizontal axis, the transmittance is highest when the vertical (V) angle is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees, 20 degrees, 30 degrees, and 40 degrees. Also, in Figure 9, in the range of light with wavelengths of approximately 400 nm to 800 nm on the horizontal axis, the transmittance is highest when the vertical (V) angle is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees, 20 degrees, 30 degrees, and 40 degrees.

[0044] 10, in the range of light with wavelengths of approximately 400 nm to 800 nm on the horizontal axis, the transmittance is highest when the angle in the horizontal (H) direction is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees and 20 degrees. Also, in Fig. 11, in the range of light with wavelengths of approximately 400 nm to 800 nm on the horizontal axis, the transmittance is highest when the angle in the horizontal (H) direction is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees and 20 degrees.

[0045] As shown in Figures 8 and 9, the reflective polarizing plate with a grid structure has poor characteristics for light coming from a direction perpendicular to the polarization axis. For this reason, specifications along the polarization axis are desirable, and the light source 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 also poor for light coming from an oblique angle. In consideration of the above characteristics, a configuration example of this embodiment will be described below in which a light source 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.

[0046] <Image display device> Next, the image display device 1 of this embodiment will be described with reference to the drawings. The image display device of this embodiment includes an image display element 11 (liquid crystal display panel) and a light source device 13 that constitutes the light source thereof, and in Fig. 12, the light source device 13 is shown together with the liquid crystal display panel as an exploded perspective view.

[0047] As shown by arrow 30 in Figure 12, this liquid crystal display panel (image display element 11) obtains a light beam having a narrow-angle diffusion characteristic from light source device 13, which is a backlight device, i.e., an illumination light beam that is highly directional (straight-line) and has characteristics similar to laser light with its polarization plane aligned in one direction, and the image light modulated according to the input video signal is reflected by retroreflective member 2 and passes through window glass 105 to form a real image, which is a floating image in space (see also Figure 1)

[0048] 12, the image display device 1 is configured to include a liquid crystal display panel 11, a light direction conversion panel 54 for adjusting 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 image light of a specific polarized wave is modulated in intensity by a video signal and emitted (see arrow 30 in FIG. 12). As a result, a desired image is projected 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, it is transmitted toward the eyes of a viewer outside the store (space) to form a space floating image 3. A protective cover 50 (see FIGS. 13 and 14) may be provided on the surface of the light direction conversion panel 54 described above.

[0049] In this embodiment, in order to improve the utilization efficiency of the light beam 30 emitted from the light source device 13 and significantly reduce power consumption, in an image display device 1 comprising a light source device 13 and an LCD panel 11, the light from the light source device 13 (see arrow 30 in Figure 12) is projected toward the retroreflective member 2, and after being reflected by the retroreflective member 2, the directivity can be adjusted by a transparent sheet (not shown) provided on the surface of the window glass 105 so as to form a floating image at a desired position.

[0050] Specifically, this transparent sheet adjusts the imaging position of the floating image while providing high directivity through optical components such as a Fresnel lens or a linear Fresnel lens. This allows the image light from the image display device 1 to efficiently reach an observer outside the window glass 105 (for example, on a sidewalk) with high directivity (straightness) like laser light, and as a result, it is possible to display high-quality floating images with high resolution and significantly reduce the power consumption of the image display device 1 including the LED elements 201 of the light source device 13.

[0051] <Example of image display device 1> Fig. 13 shows an example of a specific configuration of the image display device 1. In Fig. 13, a liquid crystal display panel 11 and a light direction conversion panel 54 are arranged on the light source device 13 of Fig. 12. This light source device 13 is formed, for example, from plastic on the case shown in Fig. 12, and is configured by storing an LED element 201 and a light guide 203 inside. As shown in Fig. 12 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 total reflection multiple times during propagation inside.

[0052] The liquid crystal display panel 11 is attached on the light guide 203. Furthermore, LED (Light Emitting Diode) elements 201, which are semiconductor light sources, and an LED board 202, on which a control circuit for the LED elements is mounted, are attached to one side surface (the left end surface in this example) of the case of the light source device 13, and a heat sink, which is a member for cooling heat generated by the LED elements and the control circuit, may be attached to the outer surface of the LED board 202.

[0053] The frame (not shown) of the liquid crystal display panel 11 is attached to the top surface of the case of the light source device 13, and is configured by attaching the liquid crystal display panel 11 attached to the frame, and further by attaching an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11. That is, the liquid crystal display panel 11, which is an image 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 elements 201, which are solid-state light sources. At this time, the generated image light has a narrow diffusion angle and contains only specific polarization components, so that an unprecedented new image display device is obtained that is similar to a surface-emitting laser image source driven by an image signal.

[0054] At present, it is technically and safety impossible for a laser device to obtain a laser beam of a size equivalent to that of an image obtained by the above-mentioned image display device 1. Therefore, in this embodiment, light close to the above-mentioned surface-emitting laser image light is obtained from a beam from a general light source equipped with, for example, an LED element.

[0055] 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. 13 as well as FIG.

[0056] 13 and 14 are cross-sectional views, and only one of the LED elements 201 constituting the light source is shown, and this is converted into approximately collimated light by the shape of the light-receiving end surface 203a of the light guide 203. For this reason, the light-receiving part of the end surface of the light guide and the LED element are attached while maintaining a predetermined positional relationship.

[0057] Each of the light guides 203 is formed of a light-transmitting resin such as acrylic. The LED light receiving surface at the end of the light guide 203 has a cone-shaped outer circumferential surface obtained by rotating a parabolic cross section, and at the top of the light guide 203, 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 (not shown). The outer shape of the light receiving portion of the light guide to which the LED element 201 is attached is a parabolic shape forming a cone-shaped outer circumferential surface, and is set within an angle range in which the light emitted from the LED element in the peripheral direction can be totally reflected inside the parabolic shape, or a reflective surface is formed.

[0058] On the other hand, the LED elements 201 are arranged at predetermined positions on the surface of the LED substrate 202, which is the circuit substrate. The LED substrate 202 is arranged and fixed such that the LED elements 201 on the surface are positioned in the center of the recessed portion described above with respect to the collimator (light-receiving end surface 203a).

[0059] 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.

[0060] 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 end surface, 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 (in a direction perpendicular to the front side of the drawing). The uniformity of the light beam incident on the liquid crystal display panel 11 can be adjusted 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.

[0061] 13 or 14, 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 substantially parallel to the light guide 203 (in a direction perpendicular to the front side of the drawing) by providing a portion with a different refractive index in the shape of the surface of the light guide or inside the light guide. At this time, when the brightness of the screen center and the screen periphery are compared while facing the liquid crystal display panel 11 directly at the center of the screen and placing the 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.

[0062] 13 is a cross-sectional layout diagram for explaining the configuration and operation of a light source of this embodiment that performs polarization conversion in light source device 13 including the above-mentioned light guide 203 and LED element 201. In Fig. 13, light source device 13 is composed of light guide 203 formed of, for example, plastic or the like and having light beam direction conversion means 204 on its surface or inside, LED element 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc., and on the upper surface thereof is attached liquid crystal display panel 11 equipped with polarizing plates on the light source light entrance surface and image light exit surface.

[0063] Furthermore, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects one polarized wave (e.g., P wave) 212 of the natural light beam 210 emitted from the LED element 201, and the reflected light beam is reflected by a reflective sheet 205 provided on one surface (lower surface in the figure) of the light guide 203, and directed again toward the liquid crystal display panel 11. Therefore, a retardation plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the reflected light beam is reflected by the reflective sheet 205 and passes through it twice, thereby converting the reflected light beam from P polarized light to S polarized light, thereby improving the utilization efficiency of the light source light as image light.

[0064] The image light beam, the light intensity of which is modulated by the image signal in the liquid crystal display panel 11 (arrow 213 in Figure 13), enters the retroreflective member 2 and, after reflection, passes through the window glass 105, as shown in Figure 1, to obtain a real image, that is, a floating image in space, inside or outside the store (space).

[0065] Fig. 14 is a cross-sectional layout diagram for explaining the configuration and action of a light source of this embodiment that performs polarization conversion in light source device 13 including light guide 203 and LED element 201, similar to Fig. 13. Light source device 13 is also similarly composed of light guide 203 formed of, for example, plastic and provided with light beam direction conversion means 204 on its surface or inside, LED element 201 as a light source, reflective sheet 205, retardation plate 206, lenticular lens, etc. On light guide 203, liquid crystal display panel 11 having polarizing plates on the light source light entrance surface and image light exit surface is attached as an image display element.

[0066] Furthermore, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects one polarized wave (for example, S wave) 211 of the natural light beam 210 emitted from the LED light source 201, which is reflected by a reflective sheet 205 provided on one surface (the lower surface in the figure) of the light guide 203, and travels again toward the liquid crystal display panel 11. A retardation plate (λ / 4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the reflected light beam is reflected by the reflective sheet 205 and passes through it 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. The image light beam, which has been intensity-modulated by the image signal in the liquid crystal display panel 11 (arrow 214 in Figure 14), enters the retroreflective member 2 and, after reflection, passes through the window glass 105 as shown in Figure 1, to obtain a real image, that is, a floating image in space, inside or outside the store (space).

[0067] In the light source device shown in Fig. 13 and Fig. 14, in addition to the action of the polarizer provided on the light incidence surface of the corresponding liquid crystal display panel 11, the polarized component on one side is reflected by the reflective polarizer 49, so that the theoretically obtainable contrast ratio is the reciprocal of the cross transmittance of the reflective polarizer multiplied by the reciprocal of the cross transmittance obtained by the two polarizers attached to the liquid crystal display panel. This results in 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 was obtained that was comparable to that of a self-luminous organic EL.

[0068] <Example of image display device 2> Fig. 15 shows another example of a specific configuration of the image display device 1. The light source device 13 in Fig. 15 is similar to the light source device in Fig. 17 and the like. 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 its upper surface. In addition, LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and an LED board on which a control circuit is mounted are attached to one side of the case of the light source device 13, and a heat sink 103, which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer side of the LED board (see also Figs. 17, 18, and the like).

[0069] The liquid crystal display panel frame attached to the top surface of the case is configured to have the liquid crystal display panel 11 attached to the frame, and further, an FPC (Flexible Printed Circuits) 403 (see FIG. 7) electrically connected to the liquid crystal display panel 11, etc. 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 here) constituting the electronic device, together with the LED elements 14a and 14b, which are solid-state light sources.

[0070] <Example 1 of light source device for example 2 of image display device> Next, the configuration of the optical system including the light source device 13 housed in the case will be described in detail with reference to FIG. 17 as well as FIGS. 18(a) and (b).

[0071] 17 and 18 show LEDs 14a and 14b constituting the light source, which are attached at predetermined positions relative to the collimator 15. Each collimator 15 is formed of a light-transmitting resin such as acrylic. As shown in FIG. 18(b), the collimator 15 has a cone-shaped outer circumferential surface 156 obtained by rotating a parabolic cross section, and has a concave portion 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center at the apex (the side in contact with the LED substrate).

[0072] Also, the central part of the flat part (the side opposite to the apex) of the collimator 15 has a convex lens surface 154 protruding outward (or a concave lens surface recessed inward). The parabolic surface 156 forming the outer peripheral surface of the cone shape of the collimator 15 is set within an angle range where the light emitted from the LEDs 14a and 14b in the peripheral direction can be totally reflected therein, or a reflective surface is formed.

[0073] The LEDs 14a and 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 collimator 15 such that the LEDs 14a and 14b on the surface are located at the center of the recess 153.

[0074] According to this configuration, the light emitted from the LED 14a or 14b by the collimator 15 described above, particularly the light emitted from the central portion toward the upper side (to the right in the figure), is collected and made parallel by the two convex lens surfaces 157, 154 that form the outer shape of the collimator 15. 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 collimator 15, and is similarly collected and made parallel. In other words, the collimator 15 that has a convex lens in its center and a parabolic surface formed on its periphery makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light, and thus makes it possible to improve the utilization efficiency of the generated light.

[0075] A polarization conversion element 21 is provided on the light exit side of the collimator 15. The polarization conversion element 21 may be called a polarization conversion member. As is clear from FIG. 18, the polarization conversion element 21 is configured by combining a columnar translucent member having a parallelogram cross section (hereinafter, a parallelogram column) and a columnar translucent member having a triangular cross section (hereinafter, a triangular column), and arranging them in an array in parallel to a plane perpendicular to the optical axis of the parallel light from the collimator 15. Furthermore, a polarization beam splitter (hereinafter, abbreviated as "PBS film") 211 and a reflection film 212 are alternately provided at the interface between the adjacent translucent members arranged in the array. In addition, a λ / 2 phase plate 213 is provided on the exit surface from which the light incident on the polarization conversion element 21 and transmitted through the PBS film 211 exits.

[0076] 18(a) is provided on the exit surface of this polarization conversion element 21. That is, the light emitted from the LED 14a or 14b is collimated by the action of the collimator 15, enters the synthesizing / diffusing block 16, is diffused by the texture 161 on the exit side, and then reaches the light guide 17.

[0077] The light guide 17 is a rod-shaped member made of a translucent resin such as acrylic and having a substantially triangular cross section (see Figure 18(b)). As is clear from Figure 17, the light guide 17 comprises a light input portion (surface) 171 which faces the output surface of the synthetic diffusion block 16 via a first diffuser plate 18a, a light guide light reflecting portion (surface) 172 which forms an inclined surface, and a light guide light output portion (surface) 173 which faces the liquid crystal display panel 11, which is the liquid crystal display element, via a second diffuser plate 18b.

[0078] 17, a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape on the light guide light reflecting portion (surface) 172 of the light guide 17. The reflective surface 172a (a line segment sloping upward to the right in the figure) forms an angle αn (n: natural number, for example, 1 to 130 in this example) with the horizontal plane indicated by the dashed line in the figure, and as an example, αn is set to 43 degrees or less (but 0 degree or more) here.

[0079] On the other hand, light guide entrance portion (surface) 171 of light guide 17 is formed in a curved convex shape inclined toward the light source side as shown in FIG.

[0080] In light source device 13 configured as described above, the parallel light emitted from the exit surface of synthetic diffusion block 16 is diffused via first diffusion plate 18a and enters light guide entrance portion (surface) 171 of light guide 17. As is clear from Fig. 17, when the light entered light guide 17 enters light guide entrance portion (surface) 171, it is bent (deflected) slightly upward and reaches light guide light reflection portion (surface) 172, and is reflected by the reflection surface (172a) of light guide light reflection portion (surface) 172 to reach liquid crystal display panel 11 provided on the exit surface at the top of Fig. 17.

[0081] According to the image display device 1 described above in detail, it is possible to improve the light utilization efficiency and the uniform illumination characteristics, and at the same time, 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 collimator 15, but the present invention is not limited to this, and the same action and effect can be obtained by providing it in the optical path leading to the liquid crystal display panel 11.

[0082] In addition, in the light guide light reflection portion (surface) 172, a large number of reflection surfaces 172a and connection surfaces 172b are alternately formed in a sawtooth shape, and the illumination light beam is totally reflected on each reflection surface 172a and directed upward, and furthermore, a narrow-angle diffusion plate is provided in the light guide light exit portion (surface) 173 to make the illumination light beam into a substantially parallel diffused light beam, which is incident on the light direction conversion panel 54 that adjusts the directional characteristics, 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 surface 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.

[0083] <Example 2 of light source device for example 2 of image display device> Another example of the configuration of the optical system of the light source device 13 and the like is shown in FIG. 19. In the optical system shown in FIG. 19, similar to the example shown in FIG. 18, a plurality of (two in this example) LEDs 14a and 14b constituting the light source are shown, and these are attached at a predetermined position with respect to the collimator 15. Each of the collimators 15 is formed of a light-transmitting resin such as acrylic. Similarly to the example shown in FIG. 18, the collimator 15 has a cone-shaped outer peripheral surface 156 obtained by rotating a parabolic cross section, and at the top of the collimator 15, a concave portion 153 having a convex portion (i.e., a convex lens surface) 157 formed in the center thereof is shown. Also, the center of the flat portion of the collimator 15 has a convex lens surface 154 protruding outward (or may be a concave lens surface recessed inward) 154. The parabolic surface 156 forming the cone-shaped outer peripheral surface of the collimator 15 is set within an angle range in which the light emitted from the LED 14a in the peripheral direction can be totally reflected therein, or a reflective surface is formed thereon.

[0084] The LEDs 14a and 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 collimator 15 such that the LEDs 14a and 14b on the surface are located at the center of the recess 153.

[0085] According to this configuration, the light emitted from the LED 14a or 14b by the collimator 15 described above, particularly the light emitted from the central portion toward the upper side (to the right in the figure), is collected and made parallel by the two convex lens surfaces 157, 154 that form the outer shape of the collimator 15. 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 collimator 15, and is similarly collected and made parallel. In other words, the collimator 15 that has a convex lens in its center and a parabolic surface formed on its periphery makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light, and thus makes it possible to improve the utilization efficiency of the generated light.

[0086] A light guide 170 is provided on the light emission side of the collimator 15 via a first diffusion plate 18a. The light guide 170 is a rod-shaped member having a substantially triangular cross section (see FIG. 19(a)) made of a light-transmitting resin such as acrylic, and as is clear from FIG. 19(a), includes an entrance portion (surface) 171 of the light guide light 170 that faces the emission surface of the diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (surface) 172 that forms an inclined surface, and a light guide light emission portion (surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via a reflective polarizing plate 200.

[0087] If this reflective polarizer 200 is selected to have, for example, the property of reflecting P-polarized light (and transmitting S-polarized light), it will reflect the P-polarized light in the natural light emitted from the LED light source, pass through the λ / 4 plate 202 provided in the light guide light reflecting section 172 shown in Figure 19(b), be reflected by the reflective surface 201, and pass through the λ / 4 plate 202 again 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.

[0088] Similarly, if a material having the property of reflecting S-polarized light (transmitting P-polarized light) is selected as reflective polarizer 200, it will reflect the S-polarized light in the natural light emitted from the LED light source, pass through λ / 4 plate 202 provided on light guide light reflector 172 shown in Fig. 19(b), be reflected by reflecting surface 201, and pass through λ / 4 plate 202 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. Polarization conversion can also be achieved with the configuration described above.

[0089] <Example 3 of image display device> Next, another example of the specific configuration of the image display device 1 (example 3 of the image display device) will be described with reference to Fig. 16. The light source device of this image display device 1 converts a divergent light beam of light (a mixture of P-polarized light and S-polarized light) from an LED into a substantially parallel light beam by a collimator 18, and reflects the parallel light toward the liquid crystal display panel 11 by the reflecting surface of a reflective light guide 304. The reflected light is incident on a reflective polarizing plate 49 arranged between the liquid crystal display panel 11 and the reflective light guide 304.

[0090] A specific polarized wave (for example, P-polarized light) is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. The other polarized wave (for example, S-polarized light) is reflected by the reflective polarizing plate and travels again toward the reflective light guide 304. The reflective polarizing plate 49 is installed at an angle not perpendicular to the chief ray of the light from the reflective surface of the reflective light guide 304, and the chief ray of the light reflected by the reflective polarizing plate 49 enters the transmission surface of the reflective light guide 304.

[0091] The light incident on the transmission surface of the reflective light guide 304 transmits through the back surface of the reflective light guide 304, transmits through the λ / 4 plate 270 which is a retardation plate, and is reflected by the reflector 271. The light reflected by the reflector 271 transmits through the λ / 4 plate 270 again, and then transmits through the transmission surface of the reflective light guide 304. The light transmitted through the transmission surface of the reflective light guide 304 enters the reflective polarizing plate 49 again.

[0092] At this time, the light re-entering the reflective polarizing plate 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarized wave (for example, P-polarized light) that is transmitted through the reflective polarizing plate 49. Therefore, the light whose polarization has been converted is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that, with regard to the polarization design related to the polarization conversion, the polarization may be configured inversely from the above explanation (S-polarized light and P-polarized light may be reversed).

[0093] As a result, the light from the LEDs is aligned to a specific polarization (e.g., P polarization), enters the liquid crystal display panel 11, and is brightness-modulated according to the video signal to display an image on the panel surface. As in the above example, multiple LEDs that constitute the light source are provided (however, because it is a vertical cross section, only one LED is shown in FIG. 16), and these are attached at a predetermined position relative to the collimator 18.

[0094] Each of the collimators 18 is formed of a light-transmitting resin such as acrylic or glass. The collimator 18 may have a cone-shaped convex outer periphery obtained by rotating a parabolic cross section. The top of the collimator 18 may have a concave portion with a convex portion (i.e., a convex lens surface) formed in the center. The center of the flat portion has a convex lens surface protruding outward (or may have a concave lens surface recessed inward). The parabolic surface forming the cone-shaped outer periphery of the collimator 18 is set within an angle range that allows the light emitted from the LED in the peripheral direction to be totally reflected therein, or a reflective surface is formed.

[0095] The LEDs are arranged at predetermined positions on the surface of the circuit board, that is, the LED board 102. The LED board 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface are located at the center of the apex of the cone-shaped convexity (or at the concave portion if the apex has a concave portion).

[0096] According to this configuration, among the light emitted from the LED by the collimator 18, the light emitted from the central part is condensed into parallel light by the convex lens surface forming the outer shape of the collimator 18. The light emitted from the other parts toward the periphery is reflected by the parabolic surface forming the outer peripheral surface of the cone shape of the collimator 18, and is condensed into parallel light in the same manner. In other words, according to the collimator 18 having a convex lens in its center and a parabolic surface formed on its periphery, it is possible to extract almost all of the light generated by the LED as parallel light, and it is possible to improve the utilization efficiency of the generated light.

[0097] The above configuration is the same as that of the light source device of the image display device shown in Fig. 17, Fig. 18, etc. Furthermore, the light converted into approximately parallel light by the collimator 18 shown in Fig. 16 is reflected by the reflective light guide 304. Of the light, light of a specific polarized wave is transmitted through the reflective polarizing plate 49 by the action of the reflective polarizing plate 49, and light of the other polarized wave reflected by the action of the reflective polarizing plate 49 is transmitted through the light guide 304 again. The light is reflected by the reflector 271 located opposite to the liquid crystal display panel 11 with respect to the reflective light guide 304. At this time, the light is polarized and converted by passing twice through the λ / 4 plate 270, which is a retardation plate.

[0098] The light reflected by the reflector 271 passes through the light guide 304 again and enters the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarized and converted, it passes through the reflective polarizer 49 and enters the liquid crystal display panel 11 with the polarization direction aligned. As a result, all the light from the light source can be used, and the geometrical optical utilization efficiency of light is doubled. In addition, since the degree of polarization (extinction ratio) of the reflective polarizer is also included in the extinction ratio of the entire system, the use of the light source device of this embodiment significantly improves the contrast ratio of the entire display device.

[0099] The light reflection diffusion angle at each reflective surface can be adjusted by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector 271 can be adjusted for each design so that the uniformity of the light incident on the liquid crystal display panel 11 is more suitable.

[0100] In the example described in Fig. 16, the λ / 4 plate 270, which is a retardation plate, is configured to have a phase difference of λ / 4 with respect to polarized light perpendicularly incident on the λ / 4 plate 270, but this configuration is not necessarily required. In the configuration of Fig. 16, the λ / 4 plate 270 may be a retardation plate in which the phase changes by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the incidence angle distribution of the polarized light.

[0101] <Example 4 of image display device> Further, another example (Example 4 of the image display device) of the configuration of the optical system such as the light source device of the display device will be described with reference to Fig. 25. Fig. 25 shows a configuration example in which a diffusion sheet is used instead of the reflective light guide 304 in the light source device of Example 3 of the image display device.

[0102] Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) that convert the diffusion characteristics in the vertical and horizontal directions (front and back directions in the figure, not shown) of the drawing are used on the light emission side of collimator 18, and light from collimator 18 is made to enter between the two optical sheets (diffusion sheets). This optical sheet may be a single sheet instead of a two-sheet configuration. In the case of a single-sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes on the front and back surfaces of the single optical sheet.

[0103] Also, a configuration may be adopted in which multiple diffusion sheets are used and the diffusion function is shared among the individual diffusion sheets. In the example of Fig. 25, the reflection diffusion characteristics due to the front and back shapes of optical sheets 207A and 207B may be optimally designed using the number of LEDs, the divergence angle from LED substrate (optical element) 102, and the optical specifications of collimator 18 as design parameters so that the surface density of the light beam emitted from liquid crystal display panel 11 is uniform. In other words, the diffusion characteristics are adjusted by the surface shapes of multiple diffusion sheets instead of the light guide.

[0104] 25, the polarization conversion is performed in the same manner as in the display device example 3 described above. That is, in the example of FIG. 25, reflective polarizing plate 49 may be configured to have the property of reflecting S-polarized light (transmitting P-polarized light). In this case, the P-polarized light of the light emitted from the LED, which is the light source, is transmitted, and the transmitted light is incident on liquid crystal display panel 11. The S-polarized light of the light emitted from the LED, which is the light source, is reflected, and the reflected light passes through retardation plate 270 shown in FIG. 25.

[0105] Then, the light that has passed through the retardation plate 270 is reflected by the reflector 271. The light that has been reflected by the reflector 271 passes through the retardation plate 270 again and is converted into P-polarized light. The polarized light that has been converted passes through the reflective conversion plate 49 and enters the liquid crystal display panel 11. The λ / 4 plate 270, which is the retardation plate in FIG. 25, does not necessarily have to have a phase difference of λ / 4 with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270. In the configuration of FIG. 25, the λ / 4 plate 270 may be a retardation plate that changes the phase by 90° (λ / 2) by passing polarized light twice. The thickness of the retardation plate may be adjusted according to the incidence angle distribution of the polarized light. In FIG. 25 as well, the polarization design related to the polarization conversion may be configured in reverse (configuration in which S-polarized light and P-polarized light are reversed) from the above description.

[0106] In a device used for a general TV, the light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in the horizontal direction of the screen (the display direction corresponding to the X-axis of the graph in FIG. 22(A)) and the vertical direction of the screen (the display direction corresponding to the Y-axis of the graph in FIG. 22(B)), as shown, for example, in the plot curves of "conventional characteristics (X direction)" in FIG. 22(A) and "conventional characteristics (Y direction)" in FIG. 22(B).

[0107] In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel of this embodiment are, for example, as shown in the plot curves of "Example 1 (X direction)" in FIG. 22(A) and "Example 1 (Y direction)" in FIG. 22(B).

[0108] In one specific example, when the viewing angle at which the luminance is 50% (luminance reduced to about half) of the luminance when viewed from the front (angle 0 degrees) is set to 13 degrees, the angle is about 1 / 5 of the diffusion characteristic (angle 62 degrees) of a typical home TV device. Similarly, in one example of setting the vertical viewing angle unevenly between the upper and lower sides, the reflection angle of the reflective light guide and the area of ​​the reflection surface are optimized so that the upper viewing angle is suppressed (narrowed) to about 1 / 3 of the lower viewing angle.

[0109] By setting the viewing angle and other settings as described above, the amount of light in the image directed in the user's viewing direction increases dramatically (greatly improving image brightness) compared to conventional LCD TVs, and the brightness of the image becomes more than 50 times higher.

[0110] Furthermore, in the case of the viewing angle characteristics shown in "Example 2" in Fig. 22, if the viewing angle at which the luminance of the image obtained when viewed from the front (angle 0 degrees) is 50% (luminance reduced to about half), is set, the angle (narrow viewing angle) is about 1 / 12 of the diffusion characteristic (angle 62 degrees) of a typical home TV device. Similarly, in one example of setting the vertical viewing angle equally on the upper and lower sides, the reflection angle and the area of ​​the reflection surface of the reflective light guide are optimized to suppress (narrow) the vertical viewing angle to about 1 / 12 of the conventional angle.

[0111] By making such settings, the brightness (amount of light) of the image in the viewing direction (the direction of the user's line of sight) is significantly improved, becoming more than 100 times brighter, compared to conventional LCD TVs.

[0112] As described above, by setting the viewing angle to a narrow angle, the amount of light flux heading in the viewing direction can be concentrated, greatly improving the efficiency of light utilization. As a result, even if a liquid crystal display panel for general TV applications is used, it is possible to achieve a significant improvement in brightness with similar power consumption by adjusting the light diffusion characteristics of the light source device, making it possible to create an image display device that is compatible with information display systems facing bright outdoors.

[0113] When using a large LCD panel, the overall brightness of the screen can be improved by directing the light from the periphery of the screen inward toward the viewer when the viewer faces the center of the screen. Figure 20 shows the convergence angle between the long side and the short side of the LCD panel when the distance L from the LCD panel to the viewer and the panel size of the image display device (screen ratio 16:10) are used as parameters.

[0114] The diagram shown at the top of FIG. 20 is based on the premise that an image is viewed with the screen of the liquid crystal display panel vertically long (hereinafter also referred to as "portrait use"). In this case, the convergence angle can be set according to the short side of the liquid crystal display panel (see the direction of arrow V in FIG. 20 as appropriate). As a more specific example, as shown in the plot graph in FIG. 20, for example, when a 22" panel is used vertically and the viewing distance is 0.8 m, the convergence angle can be set to 10 degrees, so that image light from each corner (four corners) of the screen can be effectively projected or output toward the viewer.

[0115] Similarly, when viewing a 15" panel in portrait orientation, if the viewing distance is 0.8 m, a convergence angle of 7 degrees will allow the image light from the four corners of the screen to be effectively directed toward the viewer. As described above, the overall brightness of the screen can be improved by directing the image light from the periphery of the screen to the viewer who is in the optimum position for viewing the center of the screen depending on the size of the LCD panel and whether it is used portrait or landscape.

[0116] The basic configuration is as shown in Figure 16 above, in which a light beam with a narrow angle directional characteristic is incident on the liquid crystal display panel 11 from a light source device, and the brightness is modulated according to a video signal, so that the video information displayed on the screen of the liquid crystal display panel 11 is reflected by a retroreflective member, and the resulting spatial floating image is displayed outdoors or indoors via a transparent member 100.

[0117] A number of other examples of the light source device will be described below. Any of these other examples of the light source device may be used in place of the light source device in the example of the image display device described above.

[0118] <Another example of light source device 1> Another example of the light source device will be described with reference to Figures 26(a) and 26(b). Figure 26(a) is a diagram in which the liquid crystal display panel 11 and the diffusion plate 206 are partially omitted in order to explain the light guide 311.

[0119] 26 shows a state in which the LEDs 14 constituting the light source are mounted on a substrate 102. The LEDs 14 and the substrate 102 are attached to a reflector 300 at predetermined positions.

[0120] 26(a), the LEDs 14 are arranged in a row in a direction parallel to the side (short side in this example) of the liquid crystal display panel 11 on which the reflector 300 is arranged. In the illustrated example, the reflector 300 is arranged corresponding to the arrangement of the LEDs. Note that a plurality of reflectors 300 may be arranged.

[0121] In one embodiment, the reflectors 300 are each made of a plastic material. In other embodiments, the reflectors 300 may be made of a metal material or a glass material, but the plastic material is easier to mold, so the reflectors 300 are made of a plastic material in this embodiment.

[0122] As shown in Fig. 26(b), the inner surface (the right side in the figure) of the reflector 300 has a reflection surface (hereinafter, may be referred to as a "paraboloid") 305 having a shape obtained by cutting a paraboloid by a meridian plane. The reflector 300 converts the divergent light emitted from the LED 14 into substantially parallel light by reflecting it on the reflection surface 305 (paraboloid), and causes the converted light to be incident on an end face of the light guide 311. In one specific example, the light guide 311 is a transmissive light guide.

[0123] The reflecting surface of the reflector 300 has an asymmetric shape with respect to the optical axis of the emitted light from the LED 14. In addition, the reflecting surface 305 of the reflector 300 is a parabolic surface as described above, and the LED is disposed at the focus of the parabolic surface to convert the reflected light flux into approximately parallel light.

[0124] Because the LED 14 is a surface light source, even if it is placed at the focus of a parabolic surface, the divergent light from the LED cannot be converted into completely parallel light, but this does not affect the performance of the light source of the present invention. The LED 14 and reflector 300 are a pair, and in order to ensure the specified performance with an attachment accuracy of ±40 μm of the LED 14 to the substrate 102, the number of LEDs attached to the substrate should be a maximum of 10 or less, and considering mass production, it is better to keep it to about 5.

[0125] Although the LED 14 and the reflector 300 are partly close to each other, the temperature rise of the LED can be reduced because heat can be dissipated into the space on the opening side of the reflector 300. This makes it possible to use a plastic molded reflector 300. As a result, the shape accuracy of the reflective surface can be improved by 10 times or more compared to a reflector made of glass material, thereby improving the light utilization efficiency.

[0126] On the other hand, a reflecting surface is provided on the bottom surface 303 of the light guide 311, and the light from the LEDs 14 is converted into a parallel light beam by the reflector 300, reflected by the reflecting surface, and emitted toward the liquid crystal display panel 11 arranged opposite the light guide 311. The reflecting surface provided on the bottom surface 303 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel light beam from the reflector 300, as shown in Fig. 26. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300.

[0127] The shape of the reflecting surface provided on the bottom surface 303 may be flat. In this case, the light reflected by the reflecting surface provided on the bottom surface 303 of the light guide 311 is refracted by the refractive surface 314 provided on the surface of the light guide 311 facing the liquid crystal display panel 11, thereby adjusting the amount of light and the emission direction of the light beam heading toward the liquid crystal display panel 11 with high precision.

[0128] 26, the refracting surface 314 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300. The inclinations of the plurality of surfaces refract the light reflected by the reflective surface provided on the bottom surface 303 of the light guide 311 toward the liquid crystal display panel 11. The refracting surface 314 may be a transmitting surface.

[0129] If a diffusion plate 206 is provided in front of the liquid crystal display panel 11, the light reflected by the reflective surface is refracted toward the diffusion plate 206 due to the multiple inclinations of the refracting surface 314. That is, the extension direction of the multiple surfaces with different inclinations of the refracting surface 314 is parallel to the extension direction of the multiple surfaces with different inclinations of the reflective surface provided on the bottom surface 303. By making the extension directions of both parallel, the angle of the light can be adjusted more appropriately. On the other hand, the LED 14 is soldered to the metallic substrate 102. This allows the heat generated by the LED to be dissipated into the air via the substrate.

[0130] The reflector 300 may be in contact with the substrate 102, or a space may be left between them. When a space is left between them, the reflector 300 is attached to the housing. By leaving a space between them, the heat generated by the LED can be dissipated into the air, improving the cooling effect. As a result, the operating temperature of the LED can be reduced, realizing the maintenance of light emitting efficiency and a longer lifespan.

[0131] <Another example of light source device 2> Next, the configuration of an optical system related to a light source device in which the light utilization efficiency is improved by 1.8 times by using polarization conversion compared to the light source device shown in Fig. 26 will be described in detail with reference to Fig. 27A(1)(2), Fig. 27B(1)(2), Fig. 27C, and Fig. 27D(1)(2). Note that the sub-reflector 308 is omitted in Fig. 27A(1).

[0132] 27A, 27B, and 27C show a state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured as a pair of blocks, each including a reflector 300 and an LED 14, and are configured as a unit 312 having a plurality of blocks.

[0133] 27A(2) is the base material of the substrate 102. Generally, the metallic substrate 102 generates heat, so it is preferable to use a plastic material or the like for the substrate 320 in order to insulate (thermalize) the heat of the substrate 102. The material and shape of the reflecting surface of the reflector 300 may be the same as those of the example of the light source device in FIG.

[0134] The reflecting surface of the reflector 300 may have an asymmetric shape with respect to the optical axis of the emitted light from the LED 14. The reason for this will be explained with reference to Fig. 27A(2). In this embodiment, the reflecting surface of the reflector 300 is a parabolic surface as in the example of Fig. 26, and the center of the light emitting surface of the LED, which is a surface light source, is located at the focal position of the parabolic surface.

[0135] In addition, due to the characteristics of the paraboloid, the light emitted from the four corners of the light-emitting surface becomes approximately parallel light beams, and only the emission direction differs. Therefore, even if the light-emitting part has an area, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected if the distance between the polarization conversion element and the reflector 300 arranged in the subsequent stage is short.

[0136] In addition, even if the mounting position of the LED 14 is shifted in the XY plane with respect to the focal point of the corresponding reflector 300, an optical system can be realized that can reduce the decrease in light conversion efficiency for the above-mentioned reasons. Furthermore, even if the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light beam only moves in the ZX plane, and the mounting accuracy of the LED, which is a surface light source, can be significantly reduced. In this embodiment, the reflector 300 having a reflective surface in which a part of a paraboloid is meridionally cut out has been described, but the LED may be arranged in a part of the cutout with the entire paraboloid as the reflective surface.

[0137] On the other hand, in this embodiment, as shown in Figures 27B(1) and 27C, the divergent light from the LED 14 is reflected by the parabolic surface 321 and converted into approximately parallel light, and then the light is made incident on the end face of the downstream polarization conversion element 21, and aligned into a specific polarization by the polarization conversion element 21. With this characteristic configuration, in the present invention, the light utilization efficiency is 1.8 times that of the example in Figure 26 described above, and a highly efficient light source can be realized.

[0138] At this time, the substantially parallel light resulting from the reflection of the divergent light from the LED 14 by the parabolic surface 321 is not all uniform. Therefore, by adjusting the angular distribution of the reflected light by the reflecting surface 307 having a plurality of inclinations, it is possible for the reflected light to be incident on the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11.

[0139] In the example shown in this figure, the direction of the light (principal ray) entering the reflector from the LED is approximately parallel to the direction of the light entering the LCD panel. This arrangement is easy to arrange from a design perspective, and it is more preferable to place the heat source below the light source device, since the air can escape upwards to reduce the temperature rise of the LED.

[0140] 27B(1), in order to improve the capture rate of divergent light from LED 14, the light beam that cannot be captured by reflector 300 is reflected by sub-reflector 308 provided on light shielding plate 309 arranged on the upper part of the reflector, and is reflected by the inclined surface of sub-reflector 310 at the lower part to enter the effective area of ​​polarization conversion element 21 at the subsequent stage, thereby further improving the light utilization efficiency. That is, in this embodiment, a part of the light reflected by reflector 300 is reflected by sub-reflector 308, and the light reflected by sub-reflector 308 is reflected by sub-reflector 310 in a direction toward light guide 306.

[0141] Thus, the substantially parallel light beams aligned to a specific polarization by the polarization conversion element 21 are reflected by the reflection shape provided on the surface of the reflective light guide 306 toward the liquid crystal display panel 11 arranged opposite to the exit surface of the reflective light guide 306. At this time, the light amount distribution of the light beams incident on the liquid crystal display panel 11 is determined by the shape and arrangement of the reflector 300 described above and the prior setting or adjustment (optimum design) of the reflection surface shape (cross-sectional shape) of the reflective light guide, the inclination of the reflection surface, the surface roughness, and the like. In other words, the light amount distribution of the light beams incident on the liquid crystal display panel 11 is optimized by optimizing the above-mentioned settings or adjustments.

[0142] The shape of the reflective surface provided on the surface of the light guide 306 is such that multiple reflective surfaces are arranged opposite the exit surface of the polarization conversion element, and the inclination, area, height and pitch of the reflective surfaces are optimized according to the distance from the polarization conversion element 21, thereby making it possible to obtain the desired light quantity distribution of the light beam incident on the liquid crystal display panel 11, as described above.

[0143] The reflecting surface 307 provided on the reflective light guide can be configured to have multiple inclinations on one surface as shown in FIG. 27B(2), thereby realizing more accurate adjustment of the reflected light. Note that, in order to configure the reflecting surface to have multiple inclinations on one surface, the area used as the reflecting surface may be multiple surfaces, polyhedral surfaces, or curved surfaces. Furthermore, the diffusing action of the diffuser 206 realizes a more uniform light distribution. The light incident on the diffuser plate on the side closer to the LED realizes a uniform light distribution by changing the inclination of the reflecting surface.

[0144] In this embodiment, a plastic material such as heat-resistant polycarbonate is used as the base material of the reflecting surface 307. The angle of the reflecting surface 307 immediately after emission from the λ / 2 plate 213 varies depending on the distance between the λ / 2 plate and the reflecting surface.

[0145] In this embodiment, the LED 14 and the reflector 300 are also partially adjacent to each other, but the temperature rise of the LED can be reduced by dissipating heat into the space on the opening side of the reflector 300. Moreover, the substrate 102 and the reflector 300 may be arranged upside down as shown in Figures 27A, 27B, and 27C.

[0146] However, if the substrate 102 is placed on top, the substrate 102 will be close to the liquid crystal display panel 11, which may make the layout difficult. Therefore, as shown in the figure, placing the substrate 102 on the lower side of the reflector 300 (the side farther from the liquid crystal display panel 11) will simplify the configuration inside the device.

[0147] A light shielding plate 410 may be provided on the light incidence surface of the polarization conversion element 21 to prevent unnecessary light from entering the optical system at the subsequent stage. With this configuration, a light source device that suppresses temperature rise can be realized. The polarizing plate provided on the light incidence surface of the liquid crystal display panel 11 can reduce temperature rise by absorbing light beams with uniform polarization, and a part of the light whose polarization direction has rotated when reflected by the reflective light guide is absorbed by the incidence side polarizing plate. Furthermore, the temperature of the liquid crystal display panel 11 also rises due to absorption by the liquid crystal itself and temperature rise caused by light incident on the electrode pattern, but since there is a sufficient space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, the temperature rise of the liquid crystal display panel 11 can be suppressed by natural cooling using the space.

[0148] Fig. 27D is a modified example of the light source device of Fig. 27B(1) and Fig. 27C. Fig. 27D(1) illustrates a modified example of a part of the light source device of Fig. 27B(1). The rest of the configuration is the same as the light source device described above in Fig. 27B(1), so illustrations and repeated explanations are omitted.

[0149] 27D(1), the height of recess 319 of sub-reflector 310 is adjusted to be lower than phosphor 114 so that the chief ray of fluorescence outputted laterally (in the X-axis direction) from phosphor 114 (see the straight line extending in a direction parallel to the X-axis in FIG. 27D(1)) passes through recess 319 of sub-reflector 310. Furthermore, the height of light-shielding plate 410 is adjusted to be lower in the Z-axis direction relative to the position of phosphor 114 so that the chief ray of fluorescence outputted laterally from phosphor 114 enters the effective area of ​​polarization conversion element 21 without being blocked by light-shielding plate 410.

[0150] In addition, the reflective surface of the convex portion of the unevenness on the top of the sub-reflector 310 reflects the light reflected by the sub-reflector 308 in order to guide the light reflected by the sub-reflector 308 to the light guide 306. Therefore, the height of the convex portion 318 of the sub-reflector 310 is adjusted so that the light reflected by the sub-reflector 308 is reflected and made to enter the effective area of ​​the polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency.

[0151] 27A(2), the sub-reflector 310 is arranged to extend in one direction and has an uneven shape. Furthermore, the top of the sub-reflector 310 has unevenness having one or more recesses periodically arranged in one direction. By using such an uneven shape, it is possible to configure the main ray of the fluorescence outputted laterally from the phosphor 114 to be incident on the effective area of ​​the polarization conversion element 21.

[0152] Further, the uneven shape of the sub-reflector 310 is periodically arranged at a pitch where the recesses 319 are located at the positions where the LEDs 14 are located. That is, each of the phosphors 114 is periodically arranged along one direction corresponding to the arrangement pitch of the recesses of the uneven shape of the sub-reflector 310. Note that when the phosphor 114 is provided in the LED 14, the phosphor 114 may be expressed as a light-emitting portion of the light source.

[0153] Also, Fig. 27D(2) illustrates a modified example of a part of the light source device of Fig. 27C. The other configurations are the same as those of the light source device of Fig. 27C, so illustrations and repeated explanations are omitted. As shown in Fig. 27D(2), the sub-reflector 310 is not necessary, but as in Fig. 27D(1), the height of the light shielding plate 410 is adjusted to be lower in the Z-axis direction relative to the position of the phosphor 114 so that the main ray of the fluorescence outputted horizontally from the phosphor 114 is not blocked by the light shielding plate 410 and enters the effective area of ​​the polarization conversion element 21.

[0154] 27A, 27B, 27C, and 27D, a side wall 400 may be provided as shown in 27A(1) to prevent dust from entering the space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, to prevent stray light from being generated outside the light source device, and to prevent stray light from entering from outside the light source device. When the side wall 400 is provided, it is arranged to sandwich the space between the light guide 306 and the diffusion plate 206.

[0155] The light exit surface of the polarization conversion element 21, which emits the light polarized and converted by the polarization conversion element 21, faces the space surrounded by the side wall 400, the light guide 306, the diffusion plate 206, and the polarization conversion element 21. In addition, of the inner surface of the side wall 400, a surface of a portion that covers the space from which the light is output from the exit surface of the polarization conversion element 21 (the space to the right of the exit surface of the polarization conversion element 21 in FIG. 27B(1)) from the side is a reflective surface having a reflective film or the like. That is, the surface of the side wall 400 facing the above-mentioned space includes a reflective area having a reflective film. By making the portion of the inner surface of the side wall 400 a reflective surface, the light reflected by the reflective surface can be reused as light source light, and the brightness of the light source device can be improved.

[0156] Among the inner surfaces of the side wall 400, the surface of the portion covering the side of the polarization conversion element 21 is made to have low light reflectance (such as a black surface without a reflective film). This is because when light is reflected on the side of the polarization conversion element 21, light with an unexpected polarization state is generated, which causes stray light. In other words, by making the above surface a surface with low light reflectance, it is possible to prevent or suppress the occurrence of stray light in the image and light with an unexpected polarization state. Also, the side wall 400 may be configured to have a hole through which air can pass in part to improve the cooling effect.

[0157] 27A, 27B, 27C, and 27D have been described on the assumption that they are configured to use the polarization conversion element 21. However, these light source devices may be configured without the polarization conversion element 21. In this case, it is possible to provide a light source device at a lower cost.

[0158] <Another example of light source device 3> Next, the configuration of the optical system for a light source device using a reflective light guide 304 based on the light source device shown in Example 1 of the light source device will be described in detail with reference to Figures 28A (1), (2), (3) and 28B.

[0159] 28A shows a state where the LED 14 constituting the light source is mounted on the substrate 102, and the collimator 18 and the LED 14 are arranged as a pair of blocks, and the collimator 18 and the LED 14 are arranged as a unit 328 having a plurality of blocks. Since the collimator 18 in this embodiment is close to the LED 14, a glass material is used for the collimator 18 in consideration of heat resistance. The shape of the collimator 18 is the same as that described for the collimator 15 in FIG. 17. In addition, by providing a light shielding plate 317 in the stage before the light enters the polarization conversion element 21, it is possible to prevent or suppress the unnecessary light from entering the optical system in the subsequent stage, and to reduce the rise in temperature due to the unnecessary light.

[0160] Other configurations and effects of the light source shown in Fig. 28A are the same as those in Fig. 27A, Fig. 27B, Fig. 27C, and Fig. 27D, and therefore repeated explanations will be omitted. The light source device in Fig. 28A may be provided with a side wall, as explained in Fig. 27A, Fig. 27B, and Fig. 27C. The configurations and effects of the side walls have already been explained, and therefore repeated explanations will be omitted.

[0161] Fig. 28B is a cross-sectional view of Fig. 28A(2). The configuration of the light source shown in Fig. 28B is common to part of the structure of the light source in Fig. 18, and has already been described in Fig. 18, so repeated description will be omitted.

[0162] <Another example of light source device 4> Next, the light source device in Fig. 29 is configured with a unit 328 having a plurality of blocks, each of which is a pair of collimators 18 and LEDs 14 used in the light source device shown in Fig. 28. The configuration of an optical system relating to a light source device using LEDs and a reflective light guide 504 arranged at both ends of the rear surface of a liquid crystal display panel 11 will be described in detail with reference to Figs. 29(a), (b) and (c).

[0163] 29 shows a state in which LEDs 14 constituting a light source are mounted on a substrate 505, and these are configured as units 503 having a plurality of blocks, each of which has a pair of collimators 18 and LEDs 14. The units 503 are arranged at both ends of the rear surface of the liquid crystal display panel 11 (in this embodiment, three units are arranged side by side in the short side direction). Light output from the units 503 is reflected by a reflective light guide 504 and enters the liquid crystal display panel 11 (shown in FIG. 29(c)) arranged opposite to the units 503.

[0164] As shown in Fig. 29(c), the reflective light guide 504 is divided into two blocks corresponding to the units arranged at each end, and arranged so that the central part is the highest. Since the collimator 18 is close to the LED 14, a glass material is adopted for the collimator 18 in consideration of heat resistance to heat emitted from the LED 14. The shape of the collimator 18 is the same as that described for the collimator 15 in Fig. 17.

[0165] Light emitted from the LED 14 enters the polarization conversion element 501 via the collimator 18. In this example, the distribution of light entering the downstream reflective light guide 504 is adjusted by the shape of the optical element 81. That is, the light amount distribution of the light beam entering the liquid crystal display panel 11 is optimally designed by adjusting the shape and arrangement of the collimator 18 described above, the shape of the optical element 81, the diffusion characteristics, the shape (cross-sectional shape) of the reflective surface of the reflective light guide, the inclination of the reflective surface, and the surface roughness of the reflective surface.

[0166] 29(b), the shape of the reflecting surface provided on the surface of the reflective light guide 504 is such that a plurality of reflecting surfaces are arranged opposite the exit surface of the polarization conversion element, and the inclination, area, height, and pitch of the reflecting surfaces are optimized according to the distance from the polarization conversion element 21. Also, by dividing the area that forms the same reflecting surface (i.e., the surface that faces the polarization conversion element) into a polyhedron, the light amount distribution of the light beam incident on the liquid crystal display panel 11 can be set to a desired value (optimized) as described above.

[0167] 27B, the reflective surface provided on the reflective light guide is configured such that one surface (the area where light is reflected) has a shape with multiple inclinations (in the example of FIG. 29, the XY plane is divided into 14 areas with different inclinations), thereby enabling more accurate adjustment of the reflected light. Also, by providing a light shielding wall 507 so that the reflected light from the reflective light guide does not leak from the side of the light source device 13, it is possible to prevent the occurrence of light leakage in any direction other than the desired direction (towards the liquid crystal display panel 11).

[0168] Moreover, the units 503 arranged on the left and right of the reflective light guide 504 in Fig. 29 may be replaced with the light source device in Fig. 27. That is, a plurality of light source devices (substrate 102, reflector 300, LED 14, etc.) in Fig. 27 may be prepared and arranged in positions facing each other as shown in Fig. 29(a), (b), and (c).

[0169] Fig. 30 is a cross-sectional view showing an example of the shape of the diffusion plate 206. As described above, the divergent light output from the LED is converted into approximately parallel light by the reflector 300 or the collimator 18, converted into a specific polarized wave by the polarization conversion element 21, and then reflected by the light guide. The light beam reflected by the light guide passes through the flat portion of the incident surface of the diffusion plate 206 and enters the liquid crystal display panel 11 (see the two solid arrows indicating "reflected light from the light guide" in Fig. 30).

[0170] Furthermore, of the light emitted from the polarization conversion element 21, the divergent light beam is totally reflected by the inclined surface of the protrusion having an inclined surface provided on the incident surface of the diffusion plate 206, and enters the liquid crystal display panel 11. In order to totally reflect the light emitted from the polarization conversion element 21 by the inclined surface of the protrusion of the diffusion plate 206, the angle of the inclined surface of the protrusion is changed based on the distance from the polarization conversion element 21. If the angle of the inclined surface of the protrusion on the side far from the polarization conversion element 21 or the side far from the LED is α, and the angle of the inclined surface of the protrusion on the side close to the polarization conversion element 21 or the side close to the LED is α', then α is smaller than α' (α<α'). By setting in this way, it becomes possible to effectively utilize the polarization-converted light beam.

[0171] <Lenticular lens> One method for adjusting the diffusion distribution of the image light from the liquid crystal display panel 11 is to provide a lenticular lens between the light source device 13 and the liquid crystal display panel 11 or on the surface of the liquid crystal display panel 11 and optimize the shape of the lens. That is, by optimizing the shape of the lenticular lens, it is possible to adjust the emission characteristics of the image light (hereinafter also referred to as "image light flux") emitted in one direction from the liquid crystal display panel 11.

[0172] Alternatively or additionally, a microlens array may be arranged in a matrix on the surface of the liquid crystal display panel 11 (or between the light source device 13 and the liquid crystal display panel 11), and the arrangement may be adjusted. That is, by adjusting the arrangement of the microlens array, it is possible to adjust the emission characteristics in the X-axis and Y-axis directions of the image light beam emitted from the image display device 1, and as a result, it is possible to obtain an image display device having desired diffusion characteristics.

[0173] The effect of the lenticular lens will now be described. As described above, when a lenticular lens with an optimized lens shape is used, the following effect can be obtained. That is, the emission characteristics of the image light beam emitted from the image display device 1 are adjusted (optimized) through the lenticular lens, and the optimized image light beam is efficiently transmitted or reflected by the window glass 105, thereby obtaining a suitable floating image in space.

[0174] As a further configuration example, two lenticular lenses may be combined and arranged at a position where the image light emitted from the image display device 1 passes, or a sheet for adjusting the diffusion characteristics by arranging a microlens array in a matrix may be provided. By configuring the optical system in this way, the luminance (relative luminance) of the image light in the X-axis and Y-axis directions can be adjusted according to the reflection angle of the image light (reflection angle with the reflection in the vertical direction as the reference (0 degrees)).

[0175] In this embodiment, by using such a lenticular lens, it is possible to obtain excellent optical characteristics that are clearly different from the graphs (plot curves) of conventional characteristics, as shown in the graphs (plot curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in Fig. 22(B). Specifically, in the plot curves of Example 1 (Y direction) and Example 2 (Y direction), the brightness characteristic in the vertical direction is made steep, and further, the balance of the directional characteristics in the up and down directions (positive and negative directions of the Y axis) is changed, so that the brightness (relative brightness) of light due to reflection and diffusion can be increased.

[0176] For this reason, according to this embodiment, the image light has a narrow diffusion angle (high straightness) and contains only specific polarization components, like the image light from a surface-emitting laser image source, and can be adjusted to suppress ghost images that are generated by the retroreflective member when an image display device using conventional technology is used, and to efficiently deliver the spatially floating image generated by retroreflection to the viewer's eyes.

[0177] Furthermore, the light source device described above can provide a directional characteristic with a significantly narrower angle in both the X-axis and Y-axis directions compared to the diffusion characteristic of light emitted from a general liquid crystal display panel shown in (a) and (b) of Figure 22 (indicated as "conventional characteristic" in the figure). In this embodiment, by providing such a narrow-angle directional characteristic, it is possible to realize an image display device that outputs light of a specific polarization that outputs an image light beam that is nearly parallel toward a specific direction.

[0178] FIG. 21 shows an example of the characteristics of the lenticular lens used in this embodiment. In this example, the characteristics in the X direction (vertical direction) based on the Z axis are shown in particular, and the 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). The plot curves of the characteristics A and B shown in the graph of FIG. 21 further show an example of a characteristic in which the image light above the peak luminance is collected at about 30 degrees to increase the luminance (relative luminance). For this reason, in these characteristics A and B, as can be seen by comparing with the plot curve of the characteristic O, the luminance (relative luminance) of light is suddenly reduced in the region where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ>30°).

[0179] 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 can be adjusted, and the degree of freedom of installation of the retroreflective sheet 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 that is reflected or transmitted through the window glass 105 and formed at a desired position can be significantly improved. As a result, it is possible to efficiently reach the eyes of an observer outdoors or indoors as light with a narrow diffusion angle (high straightness) and only a specific polarized wave component. As a result, even if the intensity (brightness) of the image light from the image display device 1 is reduced, the observer can accurately recognize the image light and obtain information. In other words, by reducing the output of the image display device 1, it is possible to realize an information display system with low power consumption.

[0180] Various embodiments or examples (i.e., specific examples) to which the present invention is applied have been described above in detail. However, the present invention is not limited to only the above-mentioned embodiments (specific examples), and includes various modified examples. For example, the above-mentioned embodiments are detailed descriptions of the entire system in order to explain the present invention in an easy-to-understand manner, 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.

[0181] The light source device described above is not limited to the space floating image display device, but can also be applied to information display devices such as HUDs, tablets, digital signage, and the like.

[0182] The technology according to the present embodiment displays high-resolution, high-brightness image information in a floating state in space, allowing users to operate the system 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 provide a contactless user interface that can be used without worrying, reducing the risk of contact infection. The present invention provides such technology and contributes to the "3 Health and Well-being for All" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0183] In addition, in the technology according to the above-mentioned embodiment, the divergence angle of the emitted image light is reduced and further aligned with a specific polarization, so that only the normal reflected light is efficiently reflected by the retroreflective material, and it is 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 non-contact user interface with excellent usability that can significantly reduce power consumption. According to the present invention that provides such technology, it contributes to "9 Build resilient infrastructure, promote inclusive and sustainable development, promote innovation and promote economic growth" and "11 Make cities and towns sustainable" of the Sustainable Development Goals (SDGs) proposed by the United Nations.

[0184] Furthermore, the technology according to the above-mentioned embodiment makes it possible to form a floating image by using highly directional (linear) image light. The technology according to this embodiment makes it possible to provide a non-contact user interface with less risk of people other than the user looking at the floating image by displaying highly directional image light, even when displaying images that require high security such as those in bank ATMs and ticket vending machines at train stations, or highly confidential images that should be hidden from people directly facing the user. By providing the above-mentioned technology, the present invention contributes to "Sustainable Cities and Communities" of the Sustainable Development Goals (SDGs) proposed by the United Nations. [Explanation of symbols]

[0185] 1...image display device, 2...retroreflective member, 3...spatial image (space-floating image), 105...window glass, 100...transmissive plate, 101...polarized light separation member, 12...absorptive polarizing plate, 13...light source device, 54...light direction conversion panel, 151...retroreflective member, 102, 202...LED substrate, 203...light guide, 205...reflective sheet, 271...reflector, 206, 270...phase difference plate, 300...space-floating image, 30 1...ghost image of a floating image in space, 302...ghost image of a floating image in space, 11...liquid crystal display panel, 206...diffusion plate, 21...polarization conversion element, 300...LED reflector, 213...lambda / 2 plate, reflective light guide...306, reflecting surface...307, sub-reflector...308, 310, 81...optical element, polarization conversion element...501, unit...503, light shielding wall...507, 401, 402...light shielding plate, 320...substrate

Claims

1. A space floating image display device, A display device for displaying an image; a light source device for supplying light to the display device; A retroreflector that reflects the image light from the display device and displays a real image of a floating image in the air by the reflected light, The light source device includes: A light source; A substrate on which the light source is mounted; a reflector that reflects light from the light source; a light guide for guiding light from the reflector; A diffusion plate that diffuses light from the light guide; a second reflector that reflects a portion of the light reflected by the reflector; a third reflector that reflects the light reflected by the second reflector in a direction toward the light guide; the diffusion plate is disposed adjacent to the display device, The substrate is disposed at a position farther from the display device than the reflector. A floating image display device.

2. The space floating image display device according to claim 1, the third reflector has a projection and recess on a top portion thereof, and a reflection surface of the projection of the projection and recess reflects the light reflected by the second reflector so as to guide the light to the light guide; A floating image display device.

3. The space floating image display device according to claim 1, The third reflector has a concave-convex top portion, and the height of the concave-convex top portion is lower than the light-emitting portion of the light source. A floating image display device.

4. The space floating image display device according to claim 1, The third reflector is disposed to extend in one direction, the third reflector has a shape in which projections and recesses having one or more recesses are periodically arranged on a top portion of the third reflector along the one direction; A floating image display device.

5. The space floating image display device according to claim 4, The light source has a plurality of light emitting units, the plurality of light emitting units are periodically arranged along the one direction in accordance with a pitch of the arrangement of the concave portions of the concave and convex portions of the third reflector; A floating image display device.

6. 2. The space floating image display device according to claim 1, The light source is a light source having a planar shape, a reflecting surface of the reflector has a shape that causes a divergent light beam emitted from the flat surface of the light source having the flat shape to be reflected by the reflector and then emitted as a parallel light beam; The emission direction of the light beam reflected by the reflecting surface of the reflector is a direction perpendicular to the optical axis of the light source having the planar shape, the optical axis being perpendicular to the planar surface. A floating image display device.

7. 2. The space floating image display device according to claim 1, a reflecting surface of the reflector that reflects light from the light source, and the reflected light becomes substantially parallel light and travels toward the light guide; a propagation direction of the substantially parallel light from the reflector toward the light guide is defined as a first direction; The light source is a plurality of light sources, and the plurality of light sources are arranged in a line in a second direction. A floating image display device.

8. 2. The space floating image display device according to claim 1, The light is guided toward the display device by reflection on a reflective surface of the light guide. A space is provided between the reflecting surface of the light guide and the display device, and natural cooling is performed in the space. A floating image display device.

9. 2. The space floating image display device according to claim 1, The reflector is made of a plastic material, a glass material, or a metal material. A floating image display device.

10. 2. The space floating image display device according to claim 1, the reflecting surface of the reflector is a parabolic surface, The reflector and the light guide are arranged so that the direction of the optical axis of light entering the reflector from the light source and the direction of light entering the diffusion plate from the light guide are substantially parallel to each other. A floating image display device.

11. 2. The space floating image display device according to claim 1, The light source is a plurality of light sources. The light sources are arranged in a row in a direction parallel to a side of the diffuser plate that is on the reflector side among a plurality of sides of the diffuser plate. A floating image display device.

12. 2. The space floating image display device according to claim 1, a polarization conversion element that converts the light from the light source into polarized light in a specific direction; and side walls arranged to sandwich a space between the light guide and the diffusion plate, a light exit surface of the polarization conversion element faces a space surrounded by the side wall, the light guide, the diffusion plate, and the polarization conversion element; A floating image display device.

13. 13. The space floating image display device according to claim 12, The side wall has a vent. A floating image display device.

14. 13. The space floating image display device according to claim 12, The surface of the side wall that contacts the space is a reflective surface. A floating image display device.

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