Spatial floating video display system

Abstract

To suitably display a video to the outside of a space, with the present invention associated with sustainable development goals: 3, Good Health and Well-being; 9, Industry, Innovation and Infrastructure; 11, Sustainable Cities and Communities.SOLUTION: A spatial floating video display system comprises: a display panel for displaying a video; a light source device for supplying light to the display panel; an optical board for reflecting video light from the display panel and showing a spatial floating video of actual image in the air by reflected light; and a sensor for sensing a region including the spatial floating video after dividing it in matrix form. The sensing regions sensed by the sensor are constructed in matrix form by being arranged side by side in directions respectively parallel to the longer direction and the short direction of the spatial floating video.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a space floating image information display system and a three-dimensional sensing device used therein. [Background technology]

[0002] As a space-floating information display system, an image display device that displays an image directly to the outside and a display method that displays it as a spatial screen are already known. In addition, a detection system that reduces false detections of operations on the operation surface of a displayed spatial image is also disclosed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

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

[0004] However, the above-mentioned prior art floating image information display system and method for three-dimensionally manipulating a spatial image with high precision do not take into consideration design optimization techniques including the light source of the image display device that serves as the image source of the floating image in space.

[0005] The object of the present invention is to provide a technology for a space-floating information display system or a space-floating image display device that has high visibility (apparent resolution and contrast), a method for highly accurate three-dimensional manipulation of the displayed spatial image, and the technology for displaying suitable images with reduced false detection. [Means for solving the problem]

[0006] To solve the above problems, for example, the configuration described in the claims is adopted. The present application includes multiple means for solving the above problems, and the following provides an example of a space-floating image display device. The space-floating image display system as an example of the present application includes a display panel that displays an image, a light source device that supplies light to the display panel, an optical plate that reflects the image light from the display panel and displays a space-floating image of a real image in the air using the reflected light, and a sensor that divides an area containing the space-floating image into a matrix and senses it, and the sensing area sensed by the sensor is arranged in a matrix by being aligned in directions parallel to the long and short sides of the space-floating image. [Effects 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 three-dimensional sensing function with few false detections. Other problems, configurations, and effects will be made clear in the following description of the embodiments. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a usage form of a space floating image information display system according to an embodiment of the present invention; [Figure 2] 1 is a diagram showing an example of a main part configuration and a retroreflection part configuration of a space floating image information display system according to an embodiment of the present invention; [Figure 3] 10A and 10B are diagrams showing another example of the main part configuration and the retroreflection part configuration of the space floating image information display system according to an embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing the arrangement of members that block extraordinary rays generated by retroreflection according to an embodiment of the present invention. [Figure 5] 4 is a cross-sectional view showing the arrangement of a member that blocks extraordinary rays generated in a retroreflecting portion according to an embodiment of the present invention. FIG. [Figure 6] FIG. 1 is an explanatory diagram for explaining the function of a sensing device used in a space floating image information display system. [Figure 7] FIG. 1 is an explanatory diagram of the principle of a three-dimensional sensing system used in a space floating image information display system. [Figure 8A] 10 is an explanatory diagram for explaining the operation of a sensing device used in a space floating image information display system. FIG. [Figure 8B] 10 is an explanatory diagram for explaining the operation of a sensing device used in a space floating image information display system. FIG. [Figure 9] FIG. 2 is a characteristic diagram showing the spectral irradiance of sunlight. [Figure 10] FIG. 1 is a characteristic diagram showing the reflection characteristics of polarized light incident on a medium with a refractive index of 1.5 versus the angle of incidence of the light. [Figure 11] 1 is a diagram showing a configuration of a main part of a space floating image information display system according to an embodiment of the present invention; [Figure 12] FIG. 10 is a diagram showing the configuration of the main components of another space floating image information display system according to an embodiment of the present invention. [Figure 13] FIG. 10 is a diagram showing the configuration of the main components of another space floating image information display system according to an embodiment of the present invention. [Figure 14] 1A and 1B are diagrams illustrating an example of an effective image display on a space floating image information display system according to an embodiment of the present invention. [Figure 15] 10A and 10B are explanatory diagrams for explaining the light source diffusion characteristics of the image display device. [Figure 16] 10A and 10B are explanatory diagrams for explaining the light source diffusion characteristics of the image display device. [Figure 17] FIG. 1 is a diagram showing a coordinate system for measuring visual characteristics of a liquid crystal panel. [Figure 18] FIG. 1 is a diagram showing the luminance angle characteristics (vertical direction) of a typical liquid crystal panel. [Figure 19] FIG. 1 is a diagram showing the angle characteristics (vertical direction) of contrast of a typical liquid crystal panel. [Figure 20] FIG. 1 is a diagram showing the luminance angle characteristics (left and right direction) of a typical liquid crystal panel. [Figure 21] FIG. 1 is a diagram showing the angular characteristics (left and right direction) of contrast of a typical liquid crystal panel. [Figure 22]FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. [Figure 23] 3A and 3B are structural diagrams showing examples of specific configurations of the light source device. [Figure 24] FIG. 10 is a diagram showing an example of a specific configuration of a light source device of another type. [Figure 25] FIG. 10 is a diagram showing another example of a specific configuration of a light source device of another type. [Figure 26] FIG. 10 is a diagram showing another example of a specific configuration of a light source device of another type. [Figure 27A] FIG. 10 is a structural diagram showing another example of a specific configuration of a light source device of another type. [Figure 27B] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 27C] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 27D] FIG. 10 is a diagram illustrating a portion of another example of a specific configuration of a light source device of another type. [Figure 28A] FIG. 10 is a structural diagram showing another example of a specific configuration of a light source device of another type. [Figure 28B] FIG. 10 is a diagram showing another example of a specific configuration of a light source device of another type. [Figure 29] 10 is a structural diagram showing the surface shape of a light guide diffusion section in another example of a specific configuration of a light source device. FIG. [Figure 30] 10 is an enlarged view showing the surface shape of a light guide diffusion portion of another example of a specific configuration of a light source device. FIG. [Figure 31] FIG. 10 is a diagram for explaining the diffusion characteristics of a video display device. [Figure 32] FIG. 10 is a diagram for explaining the diffusion characteristics of a video display device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the contents of the embodiments described below (hereinafter also referred to as "the present disclosure"). The present invention also extends to the spirit of the invention and 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 may be made by those skilled in the art within the scope of the technical ideas disclosed in this specification.

[0010] Furthermore, in the drawings for explaining the present invention, components having the same or similar functions are given the same reference numerals, 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 using the term "space-floating image." Instead of this term, it is also acceptable to express it as "aerial image," "spatial image," "floating image," "space-floating optical image of displayed image," "floating optical image of displayed image," etc. The term "space-floating image," which is 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 that can display 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 shop window. The present disclosure also relates to a large-scale digital signage system configured using multiple such information display systems.

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

[0013] Furthermore, a device including the light source of the present disclosure can provide a novel and highly usable floating image information display system that can significantly reduce power consumption. Furthermore, the technology of the present disclosure can provide a floating image information display system for a vehicle that can display a so-called unidirectional floating image that can be viewed from outside the vehicle through shield glass such as the vehicle's windshield, rear window, or side window.

[0014] On the other hand, conventional floating-space image information display systems combine an organic electroluminescence (EL) panel or a liquid crystal display panel (LCD panel or display panel) as a high-resolution color display image source with a retroreflective material. In conventional floating-space image display devices, image light is diffused over a wide angle. In addition to the light normally reflected by the retroreflective material (first embodiment, shown in FIG. 2, which is composed of a polyhedron), ghost images are generated by image light incident obliquely on the retroreflective material 2a, as shown in FIG. 2(C), impairing the image quality of the floating-space image. Furthermore, in conventional floating-space image display devices, as shown in FIG. 2, multiple ghost images are generated in addition to the normal floating-space image, depending on the number of reflective surfaces. Therefore, ghost images of the same floating-space image can be viewed by people other than the viewer, posing a significant security issue.

[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 of this embodiment. Referring to FIG. 1(A), for example, in a store or the like, a space is partitioned by a show window (also called "window glass") 105, which is a translucent member such as glass. According to the space-floating information display system of the present disclosure (hereinafter also called "this system"), it is possible to transmit such transparent member and display a floating image in one direction to the outside of the store (space).

[0016] Specifically, according to this system, light with narrow-angle directional characteristics and specific polarization is emitted from image display device (display device) 1 as an image light beam, which is first incident on retroreflective member 2, retroreflected, and transmitted through window glass 105 to form a real aerial image 3 (space-floating image 3) outside the store. In FIG. 1(A), the inside of transparent member (window glass in this case) 105 (inside the store) is shown as the depth direction, and the outside of window glass 105 (e.g., the sidewalk) is shown as the foreground. Alternatively, a means for reflecting specific polarization can be provided on window glass 105, and the image light beam can be reflected by such means to form an aerial image at a desired position inside the store.

[0017] 1(B) is a block diagram showing the configuration of the above-mentioned video display device 1. Video display device 1 includes a video display unit that displays an original aerial image, a video control unit that converts an input video to match the resolution of the panel, and a video signal receiving unit that receives a video signal.

[0018] Of these, the video signal receiving unit is responsible for handling wired input signals via input interlaces such as HDMI (High-Definition Multimedia Interface (registered trademark)) and wireless input signals such as Wi-Fi (Wireless Fidelity (registered trademark)). The video signal receiving unit can also function independently as a video receiving and display device. Furthermore, the video signal receiving unit can also display video information from tablets, smartphones, etc. Furthermore, the video signal receiving unit can be connected to a processor (arithmetic processing device) such as a stick PC as needed, in which case the video signal receiving unit as a whole can be equipped with capabilities such as calculation processing and video analysis processing.

[0019] FIG. 2 is a diagram showing an example of the configuration of the main components and the retroreflection component of the spatial floating image information display system of the present disclosure. The configuration of the spatial floating image information display system will be described in more detail using 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 made of glass or other material. 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 with a narrow-angle diffusion characteristic.

[0020] Image light of a specific polarization from image display device 1 is reflected by polarization separation member 101 (in the figure, polarization separation member 101 is formed into a sheet shape and adhered to transparent member 100) which has a film that selectively reflects image light of a specific polarization and is provided on transparent member 100, and then enters 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 a specific polarization to the other polarization by passing through λ / 4 plate 21 twice, once when it enters the retroreflective member and once when it leaves.

[0021] 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.

[0022] The light that forms the floating image 3 is a collection of light rays that converge from the retroreflective member 2 onto 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 diffused image light formed on a screen by a general projector or the like.

[0023] 2, the floating image 3 will appear as a bright image when viewed by a user from the direction of arrow A, but will not appear 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 kept secret from people directly facing the user.

[0024] 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 whose polarization axis has become misaligned is reflected by the polarization separating member 101 described above 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, generating a ghost image, which may be a factor in causing a deterioration in the image quality of the spatially floating image.

[0025] Therefore, in this embodiment, an absorptive polarizer 12 is provided on the image display surface of the image display device 1. The absorptive polarizer 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 polarizer 12, it is possible to prevent or suppress degradation of image quality due to ghost images of spatially floating images.

[0026] The polarization separation member 101 may be formed of, for example, a reflective polarizing plate or a metal multilayer film that reflects specific polarized waves.

[0027] Next, Figure 2(B) shows the surface shape of a typical retroreflective member 2 manufactured by Nippon Carbide Industries Co., Ltd., used in this study. Light rays incident on the regularly arranged hexagonal prisms are reflected by the walls and bottom of the hexagonal prisms and exit as retroreflected light in a direction corresponding to the incident light. This results in a real, floating image based on the image displayed on the image display device 1. The resolution of this floating image depends not only on the resolution of the LCD panel 11 but also on the outer diameter D and pitch P of the retroreflective portion of the retroreflective member 2 shown in Figure 2(B). For example, when using a 7-inch WUXGA (1920 × 1200 pixels) LCD panel, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflective portion is 240 μm and the pitch is 300 μm, then one pixel of the floating image will be equivalent to 300 μm. This reduces the effective resolution of the floating image to approximately one-third. Therefore, in order to make the resolution of the spatial floating image equivalent 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, to suppress the occurrence of moire caused by the retroreflective material and the pixels of the liquid crystal display panel, it is advisable to design the pitch ratio of each to be a different integer multiple of one pixel. Also, it is advisable to arrange the shape of the retroreflective portion so that none of its sides overlaps any of the sides of one pixel of the liquid crystal display panel.

[0028] On the other hand, to manufacture retroreflective members at low cost, it is recommended to use the roll press method. Specifically, this method aligns the retroreflective parts and forms them on a film. The reverse shape of the shape to be formed is formed on the surface of a roll, and a UV-curable resin is applied to a base material for fixing. The resin is then passed between the rolls to form the required shape, and UV light is applied to cure the resin, resulting in the retroreflective member 2 of the desired shape.

[0029] Next, Figure 3(B) shows the surface shape of another representative retroreflective member 330 manufactured by Asukanet Co., Ltd., used in this study, to explain the operating principle. Light rays entering the structure with four regularly arranged surfaces are reflected by two of the four walls and emitted as retroreflected light in the direction corresponding to the incident light, displaying a real image, a floating image 331 (see Figure 3(A)), based on the object Ph. The resolution of this floating image, like the first retroreflective member described above, is also highly dependent on the outer diameter D and pitch P of the retroreflectors. For example, when using a 7-inch WUXGA (1920 × 1200 pixel) LCD panel, even if one pixel (one triplet) is approximately 80 μm, if the diameter D of the retroreflectors is 120 μm and the pitch is 150 μm, then one pixel of the floating image will be equivalent to 150 μm. As a result, the effective resolution of the floating image is reduced by approximately half. Here, in order to make the resolution of the spatial floating image equivalent 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, to suppress the occurrence of moire caused by the retroreflective material and the pixels of the liquid crystal display panel, as described above, it is preferable to design the pitch ratio of each to be a different integer multiple of one pixel. Furthermore, it is preferable to arrange the shape of the retroreflective portion so that none of its sides overlaps any of the sides of one pixel of the liquid crystal display panel.

[0030] The light that forms the floating image 331 is a collection of light rays that converge from the retroreflective member 330 to the optical image of the floating image 331, and these light rays continue to travel in a straight line even after passing through the optical image of the floating image 331. Therefore, the floating image 331 is an image with high directionality, unlike the diffused image light formed on a screen by a general projector or the like.

[0031] 3(A) and (B), when viewed by a user from the direction of arrow A, the floating image 331 in space is perceived as a bright image, but when viewed by another person from the direction of arrow B, the floating image 331 in space cannot be seen at all. This characteristic, like the floating image using the first retroreflective member described above, is extremely suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from people directly facing the user.

[0032] In the second retroreflective member 330, the reflected object light is incident as R0 from one side of the retroreflective member 330, reflected by two reflecting surfaces provided on the four wall surfaces that make up the retroreflective member 330, and forms a real image, a space-floating image, on the other side, as shown in Figure 3(B). At this time, extraordinary light R1 and R2 generated by the two reflecting surfaces generate ghost images 332 and 333 shown in Figure 3(A). This causes a deterioration in the image quality of the space-floating image.

[0033] As mentioned above, the first retroreflective member generates ghost images depending on the number of reflective surfaces, whereas the second retroreflective member generates ghost images only in two specific directions depending on the angle of incidence of the object light, which reduces the influence of ghost images and enables high-quality spatial image display. For this reason, the space floating image display device described below will be limited to the system using the second retroreflective member mentioned above.

[0034] <Technical means to reduce ghost images> To realize a high-quality spatial image display device with reduced ghost images as a spatial floating image display device, specifically, to control the divergence angle of the image light from the liquid crystal panel as the image display element and bend it in the desired direction, it is recommended to provide an image light control sheet on the exit surface of the liquid crystal panel. Furthermore, a reflection light control sheet is provided on the light exit surface or light entrance surface or both of the retroreflective member to absorb the extraordinary light R1 and R2 that generate ghost images.

[0035] 4 shows a specific method for applying the image light control sheet 334 to a spatial image display device. The image light control sheet 334 is provided on the output surface of the liquid crystal panel 11, which is the image display element. In this case, the following two methods (1) and (2) are effective for reducing moiré that occurs due to interference between the pixels of the liquid crystal panel 11 and the pitch of the transmissive and light-absorbing portions of the image light control sheet 334.

[0036] (1) The vertical stripes generated by the light-transmitting portions and light-absorbing portions of the image light control sheet 334 are tilted by θ 0 with respect to the pixel arrangement of the liquid crystal panel 11 .

[0037] (2) When the pixel size of the liquid crystal panel 11 is A and the pitch of the vertical stripes of the image light control sheet 334 is B, the ratio (B / A) is selected so as not to be an integer multiple.

[0038] Each pixel on an LCD panel consists of three color pixels (RGB) arranged in parallel and is generally square, making it impossible to suppress the occurrence of moire across the entire screen. Therefore, we experimentally determined that the tilt θ0 shown in (1) should be optimized between 5 and 25 degrees so that the moire occurrence position can be intentionally shifted to a location where the spatial floating image is not displayed. While we have used an LCD panel as an example to reduce moire, the moire that occurs between the retroreflective member 103 and the image light control sheet 334 is a linear structure. Therefore, as shown in Figure 4, by optimally tilting the image light control sheet 334 with respect to the X-axis, it is possible to reduce large, low-frequency moire that can be seen with the naked eye even with long wavelengths.

[0039] 5(A) is a vertical cross-sectional view of the image display device 1 of the present invention, in which an image light control sheet 334 is arranged on the image light output surface of the liquid crystal panel 11. The image light control sheet 334 is configured by alternately arranging light-transmitting portions 336 and light-absorbing portions 337, and is adhesively fixed to the image light output surface of the liquid crystal panel 11 by an adhesive layer 338.

[0040] Furthermore, as mentioned above, when a 7-inch WUXGA (1920 × 1200 pixels) liquid crystal display panel is used as the image display device 1, even if one pixel (one triplet) (A in the figure) is approximately 80 μm, if the pitch B of the image light control sheet 334, consisting of a 300 μm transmissive portion d2 and a 40 μm light absorbing portion d1, is 340 μm, sufficient transmission characteristics can be achieved and the diffusion characteristics of the image light from the image display device, which causes abnormal light, can be controlled, thereby reducing ghost images that appear on both sides of the spatially floating image. In this case, if the thickness of the image control sheet is at least two-thirds of the pitch B shown in FIG. 5(A), the ghost reduction effect can be significantly improved.

[0041] FIG. 5B shows a vertical cross-sectional view of a retroreflective member according to the present disclosure, in which an image light control sheet 334 is disposed on the image light exit surface of the retroreflective member 103. The image light control sheet 334 is configured with alternating light-transmitting portions 336 and light-absorbing portions 337, tilted at an inclination angle θ1 to match the direction of retroreflected light. This configuration absorbs the anomalous light generated by retroreflection while allowing the normally reflected light to pass through without loss. When using a 7-inch WUXGA (1920 × 1200 pixel) LCD panel, even if one pixel (one triplet) (A in the figure) is approximately 80 μm, a pitch B of 420 μm, consisting of a 400 μm-long transmissive portion d2 and a 20 μm-long light-absorbing portion d1 in the retroreflective member, provides sufficient transmission characteristics and controls the diffusion characteristics of the image light from the image display device that causes anomalous light in the retroreflective member, thereby reducing ghost images that appear on both sides of the spatially floating image.

[0042] The image light control sheet 334 described above also prevents external light from entering the interior of the spatial floating image display device, which leads to improved reliability of the components. For example, a viewing angle control film (VCF) from Shin-Etsu Polymer Co., Ltd. is suitable as this image light control sheet, and its structure is a sandwich structure in which transparent silicon and black silicon are alternately arranged with synthetic resin placed on the light entrance and exit surfaces, so it can be expected to have the same effect as the external light control film of this example.

[0043] <Technical means for sensing floating images in space> The following describes a sensing technology for pseudo-operating a floating image in space, enabling the viewer (operator) to connect bidirectionally to an information system via a floating image display device. Figure 6(A) is a diagram illustrating the principle of the first sensing technology. The floating image FI is divided into multiple areas—12 in this example—and a first distance measuring device 340 with a built-in Time of Flight (TOF) system is provided for each area. The light source, a near-infrared light-emitting diode (LED), emits light in synchronization with the system's signal. An optical element for controlling the divergence angle is provided on the LED's light-emitting side, and a pair of highly sensitive avalanche diodes with picosecond time resolution are used as light-receiving elements, aligned in four columns and three rows to correspond to the 12 areas. The LED light source emits light in synchronization with the system's signal, and the phase (Δt in Figure 8A) is shifted by the time it takes for the light to reflect off the object to be measured (the viewer's fingertip) and return to the light-receiving unit.

[0044] In this embodiment, sensing units 1 to 12 in FIG. 8A correspond to TOFs 1 to 12 in FIG. 8B and are described as an example. The sensing system's calculation unit receives signals from the system and signals generated by the avalanche diodes, which are the light-receiving units, and calculates the phase shift from the received signals to determine the distance to the target. The system can determine the direction of the target's movement by identifying which of the 12 areas the target passed through on each measurement level (a3 to a1) and calculating the travel time on each measurement level using the method described above. The timing of LED light emission and light reception by the light-receiving element for each of the 12 measurement areas are shown in FIG. 8A. The timing of LED light emission is delayed for each area to standardize the individual data.

[0045] In reality, when a viewer (operator) extends his / her finger toward the floating image FI in order to connect to an information system two-way via a floating image display device, the first sensing signal S1 sensed in an area on the sensing surface a3 farthest from the floating image FI, the second sensing signal S2 sensed in a specific area on the sensing surface a2, and the third sensing signal S3 sensed in a specific area on the third sensing surface a1 are used to calculate and process the contact position with the floating image FI from the direction of finger movement and the time difference in crossing each sensing surface. In order to obtain even more accurate position information, a position sensing surface a0 is set that is further away from the floating image FI, and the passage of the finger through the floating image FI is detected as an end signal, and the contact point with the floating image is calculated as a three-dimensional coordinate from the coordinates and the two sensing signals mentioned above.

[0046] Next, we will explain the second sensing technology. As shown in the bottom of Figure 6(B), when a viewer touches a desired coordinate (position) on the floating image in space and then removes their finger, the third sensing signal S3 sensed by the third sensing surface a1, the second sensing signal S2 sensed by the second sensing surface a2, and the first sensing signal S1 sensed by the first sensing surface a1 are sequentially transmitted to the processing circuit of the sensing system for calculation and processing, and the system recognizes that the viewer's finger has been removed from the specific coordinate on the floating image in space.

[0047] In order to connect the viewer (operator) to the information system bidirectionally via the space-floating image display device, we will explain a highly accurate sensing technology for pseudo-operating the space-floating image.

[0048] Fig. 7(A) is a principle diagram for explaining the second sensing technology. The difference from the first sensing technology shown in Fig. 6(A) is that a more accurate system is realized by adding a second distance measuring device 341 in addition to the first distance measuring device 340. As described above, the first distance measuring device 340 divides the space floating image FI into multiple areas (12 divisions in this embodiment), and has a built-in TOF (Time of Flight) system corresponding to each area.

[0049] On the other hand, the second ranging device 341 is a two-dimensional image sensor, for example, a 1 / 4-inch CMOS sensor for sensing cameras, which generally has an aspect ratio of 3:4. For this reason, in this embodiment, the sensing area of ​​the first ranging device 340 is also divided into three vertical and four horizontal sections. Although a resolution of approximately one million pixels is sufficient, unlike a typical camera system, there is no need to provide an RGB color separation filter, making it possible to achieve a smaller size and higher sensitivity even with the same number of pixels as conventional devices. Additionally, the configuration of this embodiment has high sensitivity to near-infrared light, so the object to be measured (the tip of the viewer's finger) is illuminated with the light source light of the TOF system of the first ranging device 340 at a timing determined for each area, significantly improving detection accuracy.

[0050] The system described above is shown as a block diagram in FIG. 8B. In the example of FIG. 8B, a first sensing unit is provided as an example of a first distance measuring device 340. A second sensing unit having a CMOS sensor is provided as an example of a second distance measuring device 341. Furthermore, a sensing system calculation unit is provided that performs calculations based on the sensing results of the first and second sensing units. In the example shown in this figure, for example, there are 12 TOF sensors (TOF1 to TOF12 shown in FIG. 8B). Each of the sensing surfaces a1, a2, and a3 is divided into 12 areas, and one of the divided areas is sensed. Even if the sensing surfaces a1, a2, and a3 have different depths, the corresponding areas may be sensed by the same TOF sensor. In this case, the space including the sensing surfaces a1, a2, and a3 is divided vertically into 3 and horizontally into 4, for a total of 12 areas, and each divided space is sensed by the corresponding TOF sensor. This allows for accurate three-dimensional sensing using a small number of TOF sensors. In addition, the space including the sensing surfaces a1, a2, and a3 may be divided into three parts in the depth direction at a depth corresponding to the sensing surfaces a1, a2, and a3, and each part may be further divided into three parts vertically and four parts horizontally, so that a total of 36 TOF sensors are configured to correspond to the 36 divided spaces.

[0051] As shown in Figure 7(B), in a space-floating image display device using the second sensing technology, when a viewer (operator) extends his or her finger toward the space-floating image FI to connect to an information system bidirectionally, in addition to the 3D information obtained by the first distance measuring device 340 described above, the planar resolution of the sensing surface b3 of the second distance measuring device 341, which corresponds to the sensing surface a3 farthest from the space-floating image FI, can be improved to match the resolution of the CMOS sensor used. Similarly, sensing surface b2 corresponds to sensing surface a2, and sensing surface b1 corresponds to sensing surface a1, realizing a sensing system with significantly improved planar resolution. In this case, the movement direction of the object (the viewer's fingertip) is determined by calculating the contact point with the space-floating image FI from the time difference between the crossing of each sensing surface.

[0052] To obtain even more accurate position information, a sensing surface a0 is set at a position farther away from the floating image FI, and the passage of a finger through the floating image FI is detected as an end signal. The coordinates of the surface and the two sensing signals mentioned above can then be used to determine the contact point with the floating image in more precise 3D coordinates. Furthermore, by increasing the frame rate of the CMOS sensor from 1 / 20 seconds to 1 / 30 seconds or 1 / 120 seconds, the resolution can be significantly improved, as the amount of planar information captured per unit time increases in addition to the detection accuracy in the planar direction. In this case, the position information obtained by the first sensing technology is synchronized by a synchronization signal supplied by the information system.

[0053] Furthermore, as shown in the lower part of Figure 7(B), when the viewer removes his / her finger after touching the desired coordinate (position) of the floating image in space, the third sensing signal S3 sensed by the third sensing surface a1, the second sensing signal S2 sensed by the second sensing surface a2, and the first sensing signal S1 sensed by the first sensing surface a1 are sequentially transmitted to the processing circuit of the sensing system for calculation and processing, as in the first sensing technology described above, and the system recognizes that the viewer's finger has been removed from the specific coordinate of the floating image in space.

[0054] The LED light source used in the TOF sensor described above should be near-infrared light, which has high light energy in the range beyond the visible light range (380 nm to 780 nm) that cannot be seen by the naked eye, to prevent a decrease in accuracy due to external light (sunlight) from affecting the distance measurement device. For example, it is recommended to use light of 920 nm, which has low spectral irradiance energy of sunlight, as shown in Figure 9.

[0055] <Second example of the configuration of the space floating image information display system> 11 is a diagram showing the main components of a spatial floating image information display system according to one embodiment of the present invention. This spatial image information display system is suitable for viewers to observe a spatial floating image from diagonally above. The image display device 1 comprises a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 can be configured as a liquid crystal display panel with a screen size ranging from a small one with a screen size of about 5 inches to a large one exceeding 80 inches.

[0056] Image light from the liquid crystal display panel 11 is emitted toward a retroreflective member (retroreflective portion or retroreflective plate) 330. Light from a narrow divergence angle light source device 13 (described later) is incident on the liquid crystal panel, generating an image light beam φ1 with a narrow divergence angle, which is then incident on the retroreflective member 330 to produce a space-floating image 3. The space-floating image 3 is formed at a symmetrical position on the image display device 1, with the retroreflective member 330 as the plane of symmetry. In order to eliminate ghost images that occur at this time and produce a high-quality space-floating image 3, it is advisable to provide an image light control sheet 334 on the exit side of the liquid crystal panel 11 to control the diffusion characteristics in unnecessary directions.

[0057] Furthermore, as shown in FIG. 10, it is preferable to use S-polarized light for the image light from the liquid crystal panel 11, since this theoretically increases the reflectance of reflective materials such as retroreflective materials. On the other hand, if the viewer wears polarized sunglasses, there is a problem that the floating image is reflected or absorbed by the polarized sunglasses. To address this issue, it is preferable to provide a polarization canceller 339 that optically converts part of the image light of a specific polarization into the other polarization, thereby converting it into pseudo-natural light. With this configuration, a viewer can view a good floating image in space, even when wearing polarized sunglasses.

[0058] Commercially available depolarizing elements include Cosmoshine SRF (manufactured by Toyobo Co., Ltd.) and depolarizing adhesive (manufactured by Nagase & Co., Ltd.). In the case of Cosmoshine SRF (manufactured by Toyobo Co., Ltd.), by attaching the adhesive to an image display device, interfacial reflection can be reduced and brightness can be improved. In the case of depolarizing adhesive, a colorless transparent plate and an image display device can be attached via the depolarizing adhesive. As shown in FIG. 11 , an image light control sheet 334 is also provided on the image exit surface of the retroreflective member 330. The image light control sheet 334 eliminates ghost images that appear on both sides of the normal image of the space-floating image 3 due to unwanted light. In this example, the retroreflective member 330 is tilted (θ1) relative to the horizontal axis, so that the space-floating image 3 is generated approximately perpendicular to the horizontal axis.

[0059] In addition, in this embodiment, as shown in FIG. 11, a system is provided in which a viewer can access the floating image in space by wearing a first distance measuring device 340. In this case, it is advisable to appropriately select the mounting position of the distance measuring device 340 and the viewing angle θ3 so that the size of the floating image in space can be sufficiently covered. As shown in FIG. 6 and FIG. 7, the TOF sensor of the distance measuring device 340 uses a distance measuring system divided into multiple areas, thereby improving the resolution of each sensing area. Furthermore, a second sensing technology using a CMOS sensor (the second distance measuring device 341 is not shown in FIG. 11) can also be used in combination, in which case the detection accuracy can be further improved.

[0060] In addition, in this embodiment, a light source that emits visible light with a narrow-angle directional characteristic is used, and the first distance measuring device and the second distance measuring device are placed on the main body side, thereby eliminating the impact on the sensing accuracy of the image light that forms the floating image in space.

[0061] <Third Configuration Example of the Space Floating Video Information Display System> 12 is a diagram showing another example of a space-floating image information display system. This space-floating image information display system is suitable for a viewer to observe a space-floating image from diagonally below. The image display device 1 is configured with a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics.

[0062] The liquid crystal display panel 11 can be configured as a small liquid crystal display panel with a screen size of approximately 5 inches or a large liquid crystal display panel with a screen size of over 80 inches. Image light from the liquid crystal display panel 11 is reflected by an optical path reflection mirror (also referred to as a "reflection mirror") 360 and emitted toward a retroreflective member (retroreflector or retroreflector) 330. Light from a narrow divergence angle light source device 13 (described later) is incident on the liquid crystal panel 11, generating a narrow divergence angle image light beam φ1. The image light beam φ1 is then incident on the retroreflective member 330, thereby producing a floating image. The floating image is formed at a symmetrical position on the image display device 1 with the retroreflective member 330 as a plane of symmetry. In this embodiment, the reflection mirror 360 extends the distance from the image display device 1 to the retroreflective member 330, allowing the floating image to be focused at a position away from the retroreflective member 330. Furthermore, this embodiment also has the effect of vertically expanding the floating image, as described below.

[0063] The folding mirror reflected image 360a will be explained using FIG. 12. In this embodiment, the folding mirror 360 is tilted relative to the image light beam φ1 from the image display device 1, and the incident angle θ1 of the image light is set to greater than 45 degrees, thereby obtaining an enlarged folding mirror reflected image 360a. For example, if the folding mirror 360 is positioned so that the light incident angle is 60 degrees, the vertical dimension of the folding mirror reflected image 360a appears to be approximately twice the vertical dimension of the image displayed on the LCD panel. In this case, it goes without saying that the brightness of the secondary image source is halved. Furthermore, it goes without saying that a similar enlargement effect can be obtained by tilting the folding mirror 360 toward the depth direction of the diagram in FIG. 12. On the other hand, it is recommended to use image processing techniques such as converting the aspect ratio of the image so that the displayed image does not present a visual problem even if the pixels are stretched vertically.

[0064] To eliminate ghost images generated by the space-floating image 3 and obtain a high-quality space-floating image 3, an image light control sheet 334 may be provided on the output side of the liquid crystal display panel 11 to control the diffusion characteristics in unnecessary directions, as in the second embodiment. On the other hand, an image light control sheet 334 may also be provided on the image output surface of the retroreflective member 330 to eliminate ghost images generated on both sides of the normal image of the space-floating image 3 due to unnecessary light. By tilting the retroreflective sheet 330 (θ1) relative to the horizontal axis, the space-floating image 3 can be generated approximately perpendicular to the horizontal axis. A distance measuring device 340 is attached to the system, allowing the viewer to access the space-floating image. The mounting position and viewing angle θ3 of the distance measuring device 340 should be appropriately selected to adequately cover the size of the space-floating image 3.

[0065] <Fourth Configuration Example of the Space Floating Video Information Display System> FIG. 13 shows another example of a spatially floating image information display system. This spatially floating image information display system is suitable for viewers to observe a spatially floating image from diagonally above. The image display device 1 includes a liquid crystal display panel 11 as an image display element and a light source device 13 that generates light of a specific polarization with narrow-angle diffusion characteristics. The liquid crystal display panel 11 can be a small liquid crystal display panel with a screen size of approximately 5 inches or a large liquid crystal display panel with a screen size of over 80 inches. The image light from the liquid crystal display panel 11 is reflected by an optical path folding mirror 360 and emitted toward a retroreflective member (retroreflective section or retroreflective plate) 330. Light from a narrow-divergence angle light source device 13 (described later) is incident on the liquid crystal display panel 11, generating a narrow-divergence angle image light beam φ1, which is then incident on the retroreflective member 330 to produce a spatially floating image. The spatially floating image is formed at a symmetrical position on the image display device 1 with the retroreflective member 330 as a plane of symmetry. In this embodiment, similar to the third embodiment described above, by interposing a folding mirror 360, the distance from the image display device 1 to the retroreflection member 330 can be extended, and the floating image in space can be focused at a position away from the retroreflection member 330. Furthermore, as will be described below, there is also the effect of enlarging the floating image in space 3 in the vertical direction.

[0066] The folding mirror reflected image 360a will be explained using Figure 13. By tilting the folding mirror 360 by θ2 with respect to the image light beam φ1 from the image display device 1 and setting the incident angle θ0 of the image light greater than 45 degrees, an enlarged folding mirror reflected image 360a can be obtained. For example, if the folding mirror 360 is positioned so that the light incident angle is 60 degrees, the vertical dimension of the folding mirror reflected image 360a will be perceived as being approximately twice the vertical dimension of the image displayed on the LCD panel. In this case, it is recommended to perform image processing such as converting the aspect ratio of the image so that the displayed image does not present a visual problem even if the pixels are stretched vertically.

[0067] In the fourth embodiment, the image display device 1 is configured to be positioned above the space-floating image 3. This allows for a system configuration in which image light rays are incident on the retroreflective member 330 from diagonally above. Furthermore, to focus the space-floating image 3 almost perpendicularly on the set housing, the retroreflective member 330 can be positioned at an angle (θ1) relative to the bottom surface of the set housing. This prevents degradation of the image quality of the space-floating image 3 caused by external light entering the retroreflective member 330 and penetrating the interior of the housing. To eliminate ghost images generated in the space-floating image 3 and achieve high-quality space-floating images 3, as in the second embodiment, an image light control sheet 334 may be provided on the exit side of the liquid crystal display panel 11 to control the diffusion characteristics in unnecessary directions. On the other hand, an image light control sheet 334 may also be provided on the image exit surface of the retroreflective member 330 to eliminate ghost images generated on both sides of the normal image of the space-floating image 3 due to unnecessary light. By arranging the above-described structure inside the housing 350, external light is prevented from entering the retroreflective member 330, thereby preventing the occurrence of ghost images.

[0068] In this embodiment, as with the three space-floating image information systems described above, a viewer can access the space-floating image 3 by wearing a distance measuring device 340. The mounting position and viewing angle θ3 of the distance measuring device 340 can be appropriately selected so that the size of the space-floating image can be fully covered. Furthermore, a capacitive touch panel 361 is fixed with a support member 362 and placed between the space-floating image 3 and the retroreflective member 330. By using the third sensing technology using the capacitive touch panel 361 in combination with the first sensing technology, detection accuracy can be further improved. The mounting position and viewing angle θ3 of the distance measuring device 340 can be appropriately selected so that the size of the space-floating image 3 can be fully covered. Similarly, the size and mounting position of the capacitive touch panel 361 can also be appropriately selected so that the space-floating image can be fully covered.

[0069] This capacitive touch panel employs a projected capacitive touch panel, which captures highly accurate positional information. This method involves patterning transparent ITO electrodes (in the Y-axis direction) with minute spacing and transparent copper thin film electrodes with minute spacing on both sides of a transparent glass substrate using photolithographic etching to produce a capacitive touch panel. When an object (such as the tip of a viewer's finger) approaches the transparent glass substrate, this capacitive touch panel detects changes in capacitance on both the X-axis and Y-axis electrodes, providing relative coordinates for the object. The shorter the spacing between the transparent electrodes, the higher the resolution. Furthermore, capacitive touch panels enable multi-point detection, enabling simultaneous input from multiple fingers.

[0070] <How to display floating images in space> The inventors have investigated a method for making the floating image displayed by the floating image information display system described above appear more like a floating image to the viewer of the floating image, and make it look like a pseudo-3D image. The results are shown in Figures 14(A) and 14(B).

[0071] The first image display technical means is shown in Fig. 14(A). As shown in Fig. 14(A), the floating image in space should use about 80% of the image display area of ​​the image display device 1, and it is recommended to ensure that there is a blank (black display) area in the periphery or part of the periphery. As a result, it has been found that the viewer perceives the sharpness of the floating image based on the brightness ratio between this black display area (part) and the image display area (part).

[0072] As a display method, a position off the center of the screen can be effectively utilized, and the center of the image can be positioned off the center of the panel. For example, by gradually moving image 1361 from the lower right to the upper left of the screen (see the white arrow in FIG. 14A), the sense of protrusion can be enhanced. The sense of protrusion can also be enhanced by gradually increasing the magnification rate of image 1361 as it moves, making it appear closer. On the other hand, the sense of depth can be enhanced by gradually moving image 1361 in the opposite direction of the white arrow in FIG. 14A, that is, from the upper left to the lower right of the screen. The sense of protrusion can also be enhanced by gradually decreasing the magnification rate of image 1361 as it moves, making it appear farther away.

[0073] Next, a second image display technique is shown in FIG. 14(B). As with the first image technique, the floating-in-space image should occupy approximately 80% of the image display area of ​​the image display device 1, with a blank (black) area being ensured in the periphery or a portion of the periphery. Alternatively, as shown in FIG. 14(B), an image 1362 may be added to serve as a reference for the depth direction when the observer views the floating-in-space image. The image 1362 shown in FIG. 14(B) has a fixed position and a fixed size, even when the image 1361 moves, for example, in the direction of the white arrow in FIG. 14(B). By displaying such a fixed image 1362, the image 1361 appears to be displayed in front of the image 1362 (or the reference image) behind it, significantly improving the sense of the image 1361 popping out of the floating-in-space image.

[0074] Furthermore, experiments have shown that viewers perceive the sharpness of a floating image based on the brightness ratio between the black display area (part) and the image display area (part) of the floating image. More specifically, experiments have shown that in order to view a floating image as a clear image, a brightness of 1000 (nt) or more is required when enjoying the floating image in a normal living room, 2000 (nt) or more in a living room with external light, and approximately 6000 (nt) outdoors. Furthermore, it is desirable that the absolute brightness of this black display area (part) is low, and the sharpness of the image is expressed as the contrast ratio shown in the following formula.

[0075] Contrast ratio = 100% brightness of white image / brightness of black image

[0076] Experiments have revealed that a contrast ratio of 500 or more is desirable. For this reason, the inventors have developed a light source device for LCD panels with a narrow divergence angle and a polarization conversion function, as will be described later, thereby achieving low power consumption while ensuring high brightness and high contrast.

[0077] <LCD panel performance> Incidentally, in a typical TFT (Thin Film Transistor) liquid crystal panel, the brightness and contrast performance differ depending on the light emission direction due to the mutual characteristics of the liquid crystal and polarizer. In the evaluation under the measurement environment shown in Fig. 17, the brightness and viewing angle characteristics in the vertical direction of the panel were superior at an angle slightly shifted (+5 degrees in this example) from the emission angle perpendicular to the panel surface (emission angle of 0 degrees) as shown in Fig. 11. This is because the light twisting characteristic of the liquid crystal in the vertical direction does not become 0 degrees when the applied voltage is at its maximum.

[0078] On the other hand, in Figure 19, which shows the results of measurements using Samples 1 to 3, the contrast performance in the vertical direction is excellent in the range of -15 degrees to +15 degrees, and when combined with the brightness characteristics, the best characteristics are obtained when used in the range of ±10 degrees with 5 degrees as the center.

[0079] Furthermore, the brightness and viewing angle characteristics in the left-right direction of the panel are superior at an emission angle perpendicular to the panel surface (emission angle of 0 degrees), as shown in Figure 20. This is because the liquid crystal's property of twisting light in the left-right direction becomes 0 degrees when the applied voltage is at its maximum.

[0080] Similarly, in Fig. 21 showing the results of measurements using Samples 1 to 3, the contrast performance in the left-right direction is excellent in the range of -5 degrees to -10 degrees, and when combined with the brightness characteristics, the best characteristics are obtained when used in the range of ±5 degrees around -5 degrees. Therefore, the image quality and performance of the image display device 1 are improved by setting the emission angle of the image light emitted from the liquid crystal panel to be incident on the liquid crystal panel from a direction that provides the best characteristics using the light beam direction conversion means 204 provided on the light guide 203 of the light source device 13 described above, and modulating the light using a video signal.

[0081] In order to make the most of the brightness and contrast characteristics of the liquid crystal panel as an image display element, the image quality of the floating image can be improved by setting the incident light from the light source to the liquid crystal panel within the above-mentioned range.

[0082] <Light source light control method> In this embodiment, in order to improve the utilization efficiency of the emitted light beam 30 from the light source device 13 and significantly reduce power consumption, in the image display device 1 comprising the light source device 13 and the liquid crystal display panel 11, the light from the light source device 13 is incident on the liquid crystal panel 11 at an incident angle that maximizes the characteristics of the liquid crystal panel 11, and then the image light beam is luminance-modulated in accordance with the image signal and emitted toward the retroreflective member 330. In this case, the set volume of the spatial floating image information display system is reduced, and the degree of freedom in the arrangement of the liquid crystal panel 11 and the retroreflective member 330 is increased. Furthermore, in order to form the floating image at a desired position after retroreflection and ensure optimal directionality, the following technical means are used.

[0083] A transparent sheet made of optical components such as a Fresnel lens or a linear Fresnel lens is provided on the image display surface of the liquid crystal panel 11 as a light direction conversion panel, and the image position of the floating image in space is determined by controlling the output direction of the incident light beam to the retroreflective optical member 330 while providing high directivity. With this configuration, as shown in Fig. 1, the image light from the image display device 1 can 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 a high-quality floating image with high resolution and significantly reduce the power consumption of the image display device 1 including the light source device 13.

[0084] <Example 1 of video display device> Fig. 22 shows another example of the specific configuration of the image display device 1. Light source device 13 in Fig. 22 is similar to the light source device in Fig. 23 etc. This light source device 13 is configured by housing LEDs, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and has a liquid crystal display panel 11 attached to its upper surface. LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and an LED board on which their control circuits are mounted are attached to one side of the case of light source device 13, and a heat sink (not shown), which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer surface of the LED board.

[0085] The liquid crystal display panel frame attached to the top surface of the case is configured to have attached thereto a liquid crystal display panel 11 attached to the frame, and further to have attached thereto 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 a liquid crystal display element, generates a display image by modulating the intensity of transmitted light together with the LED elements 14a and 14b, which are solid-state light sources, based on a control signal from a control circuit (not shown here) that constitutes the electronic device.

[0086] <Example 1 of Light Source Device for Example 1 of Image Display Device> Next, the configuration of the optical system, such as the light source device housed in the case, will be described in detail with reference to Fig. 22 as well as Figs. 23(a) and (b). Figs. 22 and 23 show LEDs 14a and 14b constituting the light source, which are attached at predetermined positions relative to a collimator 15. Each collimator 15 is formed of a light-transmitting resin such as acrylic. As also shown in Fig. 18(b), the collimator 15 has a conical convex outer peripheral surface 156 obtained by rotating a parabolic cross section, and a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center of its apex (the side in contact with the LED substrate).

[0087] Furthermore, the central part of the flat part (the side opposite to the apex) of the collimator 15 has a convex lens surface 154 that protrudes outward (or may be a concave lens surface that is recessed inward). Note that the parabolic surface 156 that forms the outer peripheral surface of the cone shape of the collimator 15 is set within an angle range that allows the light emitted from the LEDs 14a and 14b in the peripheral direction to be totally reflected therein, or a reflective surface is formed thereon.

[0088] The LEDs 14a and 14b are arranged at predetermined positions on the surface of the circuit board, that is, the LED substrate 102. The LED substrate 102 is arranged and fixed to the collimator 15 so that the LEDs 14a and 14b on the surface are located at the center of the recess 153.

[0089] According to this configuration, the collimator 15 described above condenses the light emitted from the LED 14a or 14b, particularly the light emitted upward from the central portion (toward the right in the figure), into parallel light by the two convex lens surfaces 157, 154 that form the outer shape of the collimator 15. Furthermore, the light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the conical shape of the collimator 15, and is similarly condensed into parallel light. In other words, the collimator 15, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light, thereby improving the utilization efficiency of the generated light.

[0090] A polarization conversion element 21 is provided on the light exit side of the collimator 15. The polarization conversion element 21 may also be referred to as a polarization conversion member. As is clear from FIG. 23 , this polarization conversion element 21 is configured by combining a columnar light-transmitting member having a parallelogram cross section (hereinafter referred to as a parallelogram prism) and a columnar light-transmitting member having a triangular cross section (hereinafter referred to as a triangular prism), and arranging a plurality of these in an array parallel to a plane perpendicular to the optical axis of the collimated light from the collimator 15. Furthermore, polarization beam splitters (hereinafter referred to as "PBS films") 211 and reflective films 212 are alternately provided at the interfaces between adjacent light-transmitting members arranged in the array, and a λ / 2 phase plate 213 is provided on the exit surface from which light incident on the polarization conversion element 21 and transmitted through the PBS film 211 exits.

[0091] 23(a) is further provided on the exit surface of this polarization conversion element 21. That is, the light emitted from LED 14a or 14b is converted into parallel light by the action of collimator 15, enters synthesizing diffusion block 16, is diffused by texture 161 on the exit side, and then reaches light guide 17.

[0092] The light guide 17 is a rod-shaped member made of a translucent resin such as acrylic and having an approximately triangular cross section (see Figure 23(b)), and as is clear from Figure 25, it comprises a light guide light incident portion (surface) 171 that faces the exit surface of the synthetic diffusion block 16 via a first diffuser plate 18a, a light guide light reflecting portion (surface) 172 that forms an inclined surface, and a light guide light exit portion (surface) 173 that faces the liquid crystal display panel 11, which is a liquid crystal display element, via a second diffuser plate 18b.

[0093] 23, which is a partially enlarged view, a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth pattern on the light guide light reflecting portion (surface) 172 of this light guide 17. The reflective surfaces 172a (line segments sloping upward to the right in the figure) form angles αn (n: natural number, for example, 1 to 130 in this example) with respect to the horizontal plane indicated by the dashed dotted line in the figure, and as an example, αn is set to 43 degrees or less (but 0 degree or more).

[0094] Light guide light incident portion (surface) 171 is formed in a curved convex shape inclined toward the light source. Accordingly, parallel light from the exit surface of synthetic diffusion block 16 is diffused and incident via first diffuser plate 18a, and as is clear from the figure, is bent (deflected) slightly upward by light guide light incident portion (surface) 171 before reaching light guide light reflecting portion (surface) 172, where it is reflected and reaches liquid crystal display panel 11 provided on the exit surface at the top of the figure.

[0095] According to the image display device 1 described above in detail, it is possible to further improve the light utilization efficiency and its uniform illumination characteristics, and at the same time, it is possible to manufacture a compact and low-cost device, including a modularized S-polarized light source device. In the above explanation, the polarization conversion element 21 is described as being attached after the collimator 15, but the present invention is not limited to this, and similar functions and effects can be obtained by providing it in the optical path leading to the liquid crystal display panel 11.

[0096] The light guide light reflection portion (surface) 172 has a large number of reflective surfaces 172a and connecting surfaces 172b formed alternately in a sawtooth pattern, and the illumination light beam is totally reflected by each reflective surface 172a and directed upward, and then enters the light direction conversion panel 54, which is provided with a narrow-angle diffuser plate on the light guide light output portion (surface) 173 to adjust the directivity as a substantially parallel diffused light beam, and then enters the liquid crystal display panel 11 from an oblique direction. In this embodiment, the light direction conversion panel 54 is provided between the light guide light output portion (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 output surface of the liquid crystal display panel 11.

[0097] <Example 2 of video display device> Next, another example (example 3 of image display device) of the specific configuration of the image display device 1 will be described with reference to Fig. 24. The light source device of this image display device 1 converts a divergent beam of light (a mixture of P-polarized and S-polarized light) from an LED into a substantially parallel beam by a collimator 18, and reflects the parallel beam toward the liquid crystal display panel 11 by the reflective 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.

[0098] A specific polarized wave (for example, P-polarized light) is transmitted through the reflective polarizer 49 and enters the liquid crystal display panel 11. The other polarized wave (for example, S-polarized light) is reflected by the reflective polarizer and travels again toward the reflective light guide 304. The reflective polarizer 49 is installed at an angle so as not to be 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 polarizer 49 enters the transmission surface of the reflective light guide 304.

[0099] The light incident on the transmission surface of the reflective light guide 304 is transmitted through the back surface of the reflective light guide 304, transmitted through the λ / 4 plate 270 which is a retardation plate, and reflected by the reflector 271. The light reflected by the reflector 271 is transmitted through the λ / 4 plate 270 again, and transmitted through the transmission surface of the reflective light guide 304. The light transmitted through the transmission surface of the reflective light guide 304 is incident on the reflective polarizer 49 again.

[0100] At this time, the light that re-enters the reflective polarizer 49 has passed through the λ / 4 plate 270 twice, and therefore its polarization has been converted to a polarization (for example, P-polarized light) that is transmitted through the reflective polarizer 49. Therefore, the light whose polarization has been converted passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Note that with regard to the polarization design related to the polarization conversion, the polarization may be configured in reverse from the above explanation (S-polarized light and P-polarized light may be reversed).

[0101] As a result, the light from the LED is aligned to a specific polarization (for example, P polarization), enters the liquid crystal display panel 11, and is brightness-modulated in accordance with the video signal to display an image on the panel surface. As in the above example, multiple LEDs are provided to form the light source (however, since this is a vertical cross section, only one is shown in Figure 24), and these are attached at predetermined positions relative to the collimator 18.

[0102] Each collimator 18 is formed of a translucent resin such as acrylic or glass. The collimator 18 may have a cone-shaped outer periphery obtained by rotating a parabolic cross section. The apex of the collimator 18 may have a recess with a convex portion (i.e., a convex lens surface) formed in the center. The center of the flat portion of the collimator 18 has a convex lens surface that protrudes outward (or may have a concave lens surface that is recessed inward). The parabolic surface that forms the cone-shaped outer periphery of the collimator 18 is set within an angle range that allows total reflection of the light emitted from the LED toward the periphery, or a reflective surface is formed therein.

[0103] The LEDs are arranged at predetermined positions on the surface of the circuit board, that is, the LED substrate 102. The LED substrate 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface are positioned at the center of the apex of the convex cone shape (or in the recess if there is a recess at the apex).

[0104] With this configuration, the collimator 18 focuses the light emitted from the LED, particularly the light emitted from the central portion, into parallel light by the convex lens surface that forms the outer shape of the collimator 18. Light emitted from other portions toward the periphery is reflected by the parabolic surface that forms the outer peripheral surface of the conical shape of the collimator 18, and is similarly focused into parallel light. In other words, the collimator 18, which has a convex lens in its center and a parabolic surface formed on its periphery, makes it possible to extract almost all of the light generated by the LED as parallel light, thereby improving the utilization efficiency of the generated light.

[0105] The above configuration is the same as that of the light source device of the image display device shown in Figures 11, 12, 13, etc. Furthermore, the light converted into approximately parallel light by the collimator 18 shown in Figure 24 is reflected by the reflective light guide 304. Of the light, light of a specific polarization is transmitted through the reflective polarizing plate 49 due to the action of the reflective polarizing plate 49, and light of the other polarization 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 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.

[0106] The light reflected by the reflector 271 passes through the light guide 304 again and is incident on the reflective polarizer 49 provided on the opposite surface. Since the incident light has been polarization-converted, it passes through the reflective polarizer 49 and is incident on the liquid crystal display panel 11 with its polarization direction aligned. As a result, all of the light from the light source can be used, and the geometrical optical utilization efficiency of light is doubled. Furthermore, 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.

[0107] The angle of light reflection and diffusion at each reflective surface can be adjusted by adjusting the surface roughness of the reflective surface of reflective light guide 304 and the surface roughness of reflector 271. The surface roughness of the reflective surface of reflective light guide 304 and the surface roughness of reflector 271 can be adjusted for each design to optimize the uniformity of light incident on liquid crystal display panel 11.

[0108] In the example described in Fig. 24, the λ / 4 plate 270, which is a retardation plate, is configured so that the phase difference with respect to polarized light that is perpendicularly incident on the λ / 4 plate 270 is λ / 4, but this configuration is not necessarily required. In the configuration of Fig. 27, the λ / 4 plate 270 may be a retardation plate that changes the phase by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarized light.

[0109] <Example 3 of image display device> Furthermore, another example (Example 4 of 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. 28. 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 2 of the image display device.

[0110] 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 drawing, not shown) are used on the light output 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.

[0111] 25, the reflection and diffusion characteristics due to the front and back shapes of optical sheets 207A and 207B can 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 by the light guide.

[0112] 25, 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 emitted from the LED light source is transmitted, and the transmitted light is incident on liquid crystal display panel 11. The S-polarized light emitted from the LED light source is reflected, and the reflected light passes through retardation plate 270 shown in FIG. 25.

[0113] The light that passes through the retarder 270 is reflected by the reflector 271. The light reflected by the reflector 271 passes through the retarder 270 again and is converted into P-polarized light. The polarization-converted light passes through the reflective polarizer 49 and enters the liquid crystal display panel 11. Note that the λ / 4 plate 270, which is the retarder 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 retarder in which the phase changes by 90° (λ / 2) when polarized light passes through it twice. The thickness of the retarder may be adjusted according to the incident angle distribution of the polarized light. Note that in FIG. 25 as well, the polarization design for polarization conversion may be configured in reverse (reversing the S-polarized light and the P-polarized light) from the above explanation.

[0114] In a typical TV device, 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. 32(A)) and the vertical direction of the screen (the display direction corresponding to the Y-axis of the graph in FIG. 32(B)), as shown in the plot curves of "conventional characteristics (X direction)" in FIG. 32(A) and "conventional characteristics (Y direction)" in FIG. 32(B).

[0115] 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 Figure 32(A) and "Example 1 (Y direction)" in Figure 32(B).

[0116] In one specific example, when the viewing angle at which the brightness is 50% (brightness reduced to about half) of the brightness when viewed from the front (angle of 0 degrees) is set to 13 degrees, this angle is about 1 / 5 of the diffusion characteristics of a typical home TV (angle of 62 degrees). Similarly, in one example where the vertical viewing angles are set unevenly between the upper and lower sides, the reflection angle of the reflective light guide and the area of ​​the reflective surface are optimized so that the upper viewing angle is held down (narrowed) to about 1 / 3 of the lower viewing angle.

[0117] By setting the viewing angle and other settings as described above, the amount of light in the image directed toward the user's viewing direction increases dramatically (significantly improving image brightness) compared to conventional LCD TVs, and the brightness of the image becomes more than 50 times greater.

[0118] Furthermore, in the case of the viewing angle characteristics shown in "Example 2" in Fig. 32, if the viewing angle at which the brightness of the image obtained when viewed from the front (angle of 0 degrees) is 50% (brightness reduced to about half) is set to 5 degrees, the angle (narrow viewing angle) will be about 1 / 12 of the diffusion characteristics (angle of 62 degrees) of a typical home TV device. Similarly, in an example where the vertical viewing angle is set equally on the top and bottom sides, the reflection angle and the area of ​​the reflective surface of the reflective light guide are optimized so that the vertical viewing angle is reduced (narrowed) to about 1 / 12 of the conventional value.

[0119] By making these 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 compared to conventional LCD TVs, and the brightness of the image is more than 100 times higher.

[0120] As described above, by setting the viewing angle to a narrow angle, the amount of luminous flux directed in the viewing direction can be concentrated, significantly improving light utilization efficiency. As a result, even when using a liquid crystal display panel for general TV applications, by adjusting the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with similar power consumption, making it possible to create a video display device that is compatible with information display systems facing bright outdoor environments.

[0121] When using a large LCD panel, the brightness of the screen can be improved by directing the light from the periphery of the screen inward so that it is directed toward the viewer when the viewer is facing directly at the center of the screen. Figure 15 shows the convergence angle between the long and short sides 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.

[0122] The diagram at the top of FIG. 15 is based on the assumption that the image is viewed with the screen of the liquid crystal display panel in portrait orientation (hereinafter also referred to as "portrait use"). In this case, the convergence angle can be set to match the short side of the liquid crystal display panel (see the direction of arrow V in FIG. 15 as appropriate). As a more specific example, as shown in the plot graph in FIG. 15, when a 22" panel is used portrait-wise and the viewing distance is 0.8 m, the image light from each corner (four corners) of the screen can be effectively projected or output toward the viewer by setting the convergence angle to 10 degrees.

[0123] 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 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 image light from the periphery of the screen to the viewer who is in the optimum position to view the center of the screen, depending on the size of the LCD panel and whether it is used portrait or landscape.

[0124] The basic configuration is as shown in Figure 16 above, where a light source device emits a light beam with a narrow angle of directivity onto the liquid crystal display panel 11, and the brightness is modulated according to the video signal. The video information displayed on the screen of the liquid crystal display panel 11 is then reflected by the retroreflective member, and the resulting floating image is displayed indoors or outdoors via the transparent member 100.

[0125] A number of other examples of the light source device will be described below, and 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.

[0126] As mentioned above, when a large LCD panel is used, the light from the periphery of the screen can be directed inward toward the viewer when the viewer is facing the center of the screen, improving the overall brightness of the screen, but on the other hand, binocular parallax occurs depending on whether the viewer uses their left or right eye to view the image. Figure 16 shows the convergence angle between the long side and short side of the LCD panel, calculated based on the positions of the left and right eyes, when the distance from the LCD panel to the viewer (viewing distance) L and the panel size of the image display device (screen ratio 16:10) are used as parameters.

[0127] The smaller the panel size and the closer the viewing distance, the larger the convergence angle for binocular vision by the left and right eyes. In particular, when using a small panel of 7 inches or less, the convergence angle due to binocular parallax becomes an important requirement. For this reason, for small panels of 7 inches or less, for example, the light diffusion characteristics of the light source shown in Figure 32 should be expanded or the light should be given directional characteristics, so that the image light is directed to the optimal viewing range of the system.

[0128] Furthermore, in order to obtain horizontal and vertical directional characteristics and diffusion characteristics according to the required specifications of the system, it is necessary to optimally design the shape, surface roughness, inclination, etc. of the reflective surface of the light guide of the light source device 13 mentioned above.

[0129] <Light source device example 1> Next, 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.

[0130] 23 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.

[0131] 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 example shown in the figure, the reflector 300 is arranged corresponding to the arrangement of the LEDs. Note that a plurality of reflectors 300 may be arranged.

[0132] In one embodiment, the reflectors 300 are each made of a plastic material. Alternatively, the reflectors 300 may be made of a metal material or a glass material, but plastic materials are easier to mold, so in this embodiment, plastic materials are used.

[0133] 26(b), the inner surface (right side in the figure) of the reflector 300 has a reflecting surface (hereinafter may be referred to as a "paraboloid") 305 shaped like a paraboloid cut at its meridian plane. The reflector 300 converts the divergent light emitted from the LED 14 into approximately parallel light by reflecting it off the reflecting surface 305 (paraboloid), and directs 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.

[0134] The reflecting surface of reflector 300 has a shape asymmetric with respect to the optical axis of the light emitted from LED 14. Furthermore, reflecting surface 305 of reflector 300 is a parabolic surface as described above, and by placing the LED at the focus of this parabolic surface, the light flux after reflection is converted into approximately parallel light.

[0135] 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 for the LED 14 on the substrate 102, the number of LEDs attached to the substrate should be limited to a maximum of 10 or less, and considering mass production, it is best to limit it to around 5.

[0136] Although the LED 14 and reflector 300 are close to each other in some places, 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 precision of the reflective surface can be improved by more than 10 times compared to a reflector made of glass material, thereby improving light utilization efficiency.

[0137] On the other hand, a reflective 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 beam by the reflector 300, reflected by the reflective surface, and emitted toward the liquid crystal display panel 11 disposed opposite the light guide 311. The reflective surface provided on the bottom surface 303 may have multiple surfaces with different inclinations in the traveling direction of the parallel beam from the reflector 300, as shown in Fig. 26. Each of the multiple surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel beam from the reflector 300.

[0138] The shape of the reflective surface provided on the bottom surface 303 may be flat. In this case, the light reflected by the reflective 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.

[0139] 26, the refractive 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 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 refractive surface 314 may also be a transmissive surface.

[0140] If a diffuser plate 206 is provided in front of the liquid crystal display panel 11, the light reflected by the reflective surface is refracted toward the diffuser 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 surfaces parallel, the angle of the light can be adjusted more appropriately. On the other hand, the LEDs 14 are soldered to the metallic substrate 102. This allows heat generated by the LEDs to be dissipated into the air via the substrate.

[0141] The reflector 300 may be in contact with the substrate 102, or a space may be left between them. If a space is left between them, the reflector 300 is attached to the housing. By leaving a space between them, 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, maintaining luminous efficiency and extending its lifespan.

[0142] <Another example of light source device 2> Next, the configuration of the optical system related to the 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 not shown in Fig. 27A(1).

[0143] 27A, 27B, and 27C show the state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured as a unit 312 having a plurality of blocks, with the reflector 300 and the LEDs 14 forming a pair of blocks.

[0144] 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 (heat-insulate) the heat of the substrate 102. The material and shape of the reflector 300's reflecting surface may be the same as those of the example of the light source device in FIG.

[0145] The reflecting surface of the reflector 300 may have a shape that is asymmetric with respect to the optical axis of the light emitted 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.

[0146] Furthermore, due to the characteristics of the parabolic surface, the light emitted from the four corners of the light-emitting surface also becomes approximately parallel light beams, and the only difference is the direction of emission. 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 as long as the distance between the polarization conversion element and the reflector 300 located downstream is short.

[0147] Furthermore, 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 reasons described above. Furthermore, even if the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light beam simply moves in the ZX plane, and the mounting precision of the LED, which is a surface light source, can be significantly reduced. In this embodiment, the reflector 300 having a reflective surface formed by meridionally cutting out a portion of a paraboloid has been described, but the LED may also be placed in a portion of the cutout with the entire paraboloid as the reflective surface.

[0148] 27B(1) and 27C, the present embodiment is characterized in that the divergent light from the LED 14 is reflected by the parabolic surface 321 and converted into approximately parallel light, and then the parallel light is incident on the end face of the polarization conversion element 21 at the subsequent stage, and aligned into a specific polarization by the polarization conversion element 21. With this characteristic configuration, the present invention achieves a light utilization efficiency that is 1.8 times that of the example in Fig. 26 described above, thereby realizing a highly efficient light source.

[0149] 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 light to be incident on the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11.

[0150] 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 design, and placing the heat source below the light source device is preferable because it allows air to escape upwards, reducing the temperature rise of the LED.

[0151] 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 above the reflector, and is reflected by the slope of sub-reflector 310 below to enter the effective area of ​​polarization conversion element 21 in 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.

[0152] The substantially parallel light beam, which has been aligned to a specific polarization by the polarization conversion element 21, is reflected by a reflection shape provided on the surface of the reflective light guide 306 toward the liquid crystal display panel 11 disposed opposite the light guide 306. At this time, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is optimally designed by the shape and arrangement of the reflector 300 described above, and the shape (cross-sectional shape) of the reflective surface of the reflective light guide, as well as the inclination and surface roughness of the reflective surface.

[0153] 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 achieving the desired light intensity distribution of the light beam incident on the liquid crystal display panel 11, as described above.

[0154] The reflective surface 307 provided on the reflective light guide can be configured to have multiple inclinations on one surface, as shown in Figure 27B(2), thereby achieving more accurate adjustment of reflected light. Note that, in order to configure the reflective surface to have multiple inclinations on one surface, the area used as the reflective surface may be multiple, polyhedral, or curved. Furthermore, the diffusing action of the diffuser 206 achieves a more uniform light intensity distribution. The light incident on the diffuser plate closer to the LED achieves a uniform light intensity distribution by changing the inclination of the reflective surface.

[0155] In this embodiment, a plastic material such as heat-resistant polycarbonate is used for 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.

[0156] 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. Furthermore, the substrate 102 and the reflector 300 may be arranged upside down as shown in Figures 27A, 27B, and 27C.

[0157] 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 below the reflector 300 (on the side farther from the liquid crystal display panel 11) will simplify the internal configuration of the device.

[0158] A light-shielding plate 410 may be provided on the light-incident surface of the polarization conversion element 21 to prevent unnecessary light from entering the downstream optical system. This configuration achieves a light source device that suppresses temperature rise. The polarizer provided on the light-incident surface of the liquid crystal display panel 11 reduces temperature rise by absorbing the uniformly polarized light beam of the present invention. However, when reflected by the reflective light guide, the polarization direction rotates, and some of the light is absorbed by the incident-side polarizer. 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. However, there is sufficient space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, allowing for natural cooling.

[0159] 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 portion of the light source device of Fig. 27B(1). The other configuration is the same as that of the light source device described above in Fig. 27B(1), so illustration and repeated explanation will be omitted.

[0160] 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 output 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)) can exit from 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 output laterally from phosphor 114 can enter the effective area of ​​polarization conversion element 21 without being blocked by light-shielding plate 410.

[0161] Furthermore, the reflective surface of the convex portion of the uneven 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 incident on the effective area of ​​the polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency.

[0162] 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 with one or more recesses periodically arranged in one direction. By using such an uneven shape, it is possible to configure the sub-reflector 310 so that the chief ray of the fluorescence output laterally from the phosphor 114 enters the effective area of ​​the polarization conversion element 21.

[0163] Furthermore, the concave and convex shapes of sub-reflector 310 are periodically arranged at a pitch such that concave portions 319 are located at positions where LEDs 14 are present. That is, each of phosphors 114 is periodically arranged in one direction corresponding to the pitch of the arrangement of concave portions of the concave and convex shapes of sub-reflector 310. Note that when phosphor 114 is provided in LED 14, phosphor 114 may be expressed as a light-emitting portion of the light source.

[0164] 27D(2) illustrates a modified example of a portion of the light source device of FIG. 27C. Other configurations are the same as those of the light source device of FIG. 27C, and therefore 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 chief ray of the fluorescence output laterally from the phosphor 114 is not blocked by the light-shielding plate 410 and enters the effective area of ​​the polarization conversion element 21.

[0165] 27A, 27B, 27C, and 27D, side walls 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 side walls 400 are provided, they are arranged to sandwich the space between the light guide 306 and the diffuser plate 206.

[0166] The light exit surface of the polarization conversion element 21, which emits light that has been polarization-converted by the polarization conversion element 21, faces the space surrounded by the side wall 400, the light guide 306, the diffuser plate 206, and the polarization conversion element 21. Furthermore, of the inner surfaces of the side wall 400, a portion that laterally covers the space into which 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)) uses a reflective surface having a reflective film or the like. In other words, the surface of the side wall 400 facing the space has a reflective area having a reflective film. By making this 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, thereby improving the brightness of the light source device.

[0167] Of the inner surfaces of the side wall 400, the surface that covers the side of the polarization conversion element 21 is made to have low light reflectivity (such as a black surface without a reflective film). This is because if light is reflected from the side surface of the polarization conversion element 21, light with an unexpected polarization state will be generated, causing stray light. In other words, by making the above surface a surface with low light reflectivity, it is possible to prevent or suppress the occurrence of stray light in the image and light with an unexpected polarization state. Furthermore, the side wall 400 may be configured to have holes in parts to allow air to pass through, thereby improving the cooling effect.

[0168] 27A, 27B, 27C, and 27D have been described assuming a configuration using the polarization conversion element 21. However, these light source devices may be configured without the polarization conversion element 21. In this case, a light source device can be provided at a lower cost.

[0169] <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.

[0170] 28A shows a state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured as a unit 328 having a plurality of blocks, each of which is a pair of a collimator 18 and an LED 14. Since the collimator 18 in this embodiment is located 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 unwanted light from entering the optical system in the subsequent stage, thereby reducing the temperature rise caused by the unwanted light.

[0171] 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 side walls, 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.

[0172] 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 explained in Fig. 18, so repeated explanation will be omitted.

[0173] <Another example of light source device 4> Next, the light source device of Fig. 29 is configured with a unit 328 having a plurality of blocks, each of which is a pair of the collimator 18 and the LED 14 used in the light source device shown in Fig. 28. The configuration of the optical system relating to the light source device using the LEDs and the reflective light guide 504 arranged at both ends of the back surface of the liquid crystal display panel 11 will be described in detail with reference to Figs. 29(a), (b), and (c).

[0174] 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 a collimator 18 and an LED 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.

[0175] 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 is arranged so that the central part is the highest. Because the collimator 18 is located close to the LED 14, a glass material is used for the collimator 18 in consideration of its heat resistance to the 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.

[0176] Light from LED 14 enters polarization conversion element 501 via collimator 18. The configuration is such that the distribution of light entering reflective light guide 504 at the subsequent stage is adjusted depending on the shape of optical element 81. That is, the light intensity distribution of the light beam entering liquid crystal display panel 11 is optimally designed by adjusting the shape and arrangement of collimator 18 described above, the shape of 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.

[0177] 29(b), the shape of the reflective surface provided on the surface of the reflective light guide 504 is such that a plurality of 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. Also, by dividing the area that forms the same reflective surface (i.e., the surface that faces the polarization conversion element) into a polyhedron, it is possible to set (optimize) the light intensity distribution of the light beam incident on the liquid crystal display panel 11 to a desired value, as described above.

[0178] 27B, the reflective surface provided on the reflective light guide can adjust the reflected light with higher precision by configuring one surface (the area where light is reflected) to have a shape with multiple inclinations (in the example of FIG. 29, the XY plane is divided into 14 sections with different inclinations), thereby preventing the reflected light from leaking from the side of light source device 13. Also, by providing light-shielding wall 507, it is possible to prevent light from leaking in any direction other than the desired direction (towards liquid crystal display panel 11).

[0179] Furthermore, the units 503 arranged on the left and right sides of the reflective light guide 504 in Fig. 29 may be replaced with the light source device in Fig. 27. That is, a configuration may be adopted in which a plurality of light source devices (substrate 102, reflector 300, LED 14, etc.) in Fig. 27 are prepared and these plurality of light source devices are arranged in positions facing each other, as shown in Figs. 29(a), (b), and (c).

[0180] 30 is a cross-sectional view showing an example of the shape of the diffuser 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 specific polarization by the polarization conversion element 21, and then reflected by the light guide. The light beam reflected by the light guide then passes through the flat portion of the incident surface of the diffuser 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).

[0181] Furthermore, of the light emitted from the polarization conversion element 21, the divergent light beam is totally reflected by the inclined surfaces of the protrusions having inclined surfaces provided on the incident surface of the diffuser plate 206, and then enters the liquid crystal display panel 11. In order to totally reflect the light emitted from the polarization conversion element 21 by the inclined surfaces of the protrusions of the diffuser plate 206, the angle of the inclined surfaces of the protrusions is changed based on the distance from the polarization conversion element 21. If the angle of the inclined surface of the protrusions on the side farther from the polarization conversion element 21 or farther from the LEDs is α, and the angle of the inclined surface of the protrusions on the side closer to the polarization conversion element 21 or closer to the LEDs 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.

[0182] <Technology for controlling diffusion characteristics of video display devices> 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 luminous flux") emitted in one direction from the liquid crystal display panel 11.

[0183] 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 with desired diffusion characteristics.

[0184] 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 effects 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.

[0185] 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 that adjusts the diffusion characteristics by arranging a microlens array in a matrix may be provided. By configuring the optical system in this way, the brightness (relative brightness) 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 vertical reflection as the reference (0 degrees)).

[0186] In this example, 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 Figure 32(B). Specifically, in the plot curves of Example 1 (Y direction) and Example 2 (Y direction), the luminance characteristics in the vertical direction are made steeper, and further, by changing the balance of the directional characteristics in the up and down directions (positive and negative directions of the Y axis), it is possible to increase the luminance (relative luminance) of light due to reflection and diffusion.

[0187] Therefore, 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 the ghost images that would occur in the retroreflective member when using an image display device using conventional technology, and to efficiently deliver the spatially floating image caused by retroreflection to the viewer's eyes.

[0188] Furthermore, the light source device described above can provide directional characteristics with significantly narrower angles in both the X-axis and Y-axis directions compared to the diffusion characteristics of light emitted from a general liquid crystal display panel shown in (a) and (b) of Figure 32 (indicated as "conventional characteristics" in the figures). In this embodiment, by providing such narrow-angle directional characteristics, it is possible to realize an image display device that emits light of a specific polarization, emitting nearly parallel image light beams in a specific direction.

[0189] FIG. 31 shows an example of the characteristics of the lenticular lens employed in this embodiment. This example particularly shows the characteristics in the X direction (vertical direction) relative to the Z axis. Characteristic O shows a luminance characteristic that is symmetrical vertically, with the peak of the light emission direction at an angle of approximately 30 degrees upward from the vertical direction (0 degrees). Furthermore, the plot curves of characteristic A and characteristic B shown in the graph of FIG. 31 show examples of characteristics in which the image light above the peak luminance is further concentrated at approximately 30 degrees, thereby increasing the luminance (relative luminance). Therefore, in characteristic A and characteristic B, as can be seen by comparing them with the plot curve of characteristic O, the luminance (relative luminance) of light drops sharply in the region where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ>30°).

[0190] That is, with the optical system including the lenticular lens described above, 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, significantly improving the flexibility of installation of the retroreflective sheet 2. As a result, the flexibility of the image position of the floating image that is reflected or transmitted through the window glass 105 and focused at the desired position can be significantly improved. As a result, it is possible to efficiently deliver light with a narrow diffusion angle (high linearity) and containing only specific polarization components to the eyes of viewers indoors or outdoors. This allows viewers to accurately recognize the image light and obtain information even if the intensity (brightness) of the image light from the image display device 1 is reduced. 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.

[0191] Various embodiments or examples (i.e., specific examples) to which the present invention is applied have been described in detail above. However, the present invention is not limited to the above-described embodiments (specific examples) and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0192] 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.

[0193] The technology according to this embodiment displays high-resolution, high-brightness floating images in a floating state, allowing users to operate the system without worrying about contact infection. Using the technology according to this embodiment in a system used by an unspecified number of users reduces the risk of contact infection and provides a contactless user interface that can be used without anxiety. The present invention, which provides such technology, contributes to the "Good Health and Well-Being" goal, one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0194] Furthermore, the technology according to the above-described embodiment reduces the divergence angle of the emitted image light and aligns it with a specific polarization, thereby efficiently reflecting only the normal reflected light from the retroreflective material, resulting in high light utilization efficiency and a bright, clear, floating image in space. The technology according to the present embodiment can provide a highly usable non-contact user interface that can significantly reduce power consumption. The present invention, which provides such technology, contributes to the achievement of the United Nations' Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation" and "Make cities and towns sustainable."

[0195] Furthermore, the technology according to the above-described embodiment makes it possible to form a floating image using highly directional (linear) image light. The technology according to this embodiment makes it possible to provide a non-contact user interface with low risk of people other than the user peeking at the floating image, even when displaying images that require high security, such as those in bank ATMs or train station ticket machines, or highly confidential images that should be kept secret from people directly facing the user, by displaying highly directional image light. By providing the above-described technology, the present invention contributes to "Sustainable Cities and Communities," one of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Explanation of symbols]

[0196] 1...image display device, 2,330...retroreflective member, 3...spatial image (space-floating image), 105...window glass, 100...transmissive plate, 13...light source device, 54...light direction conversion panel, 102...LED substrate, 203...light guide, 205...reflective sheet, 271...reflector, 270...λ / 4 plate (phase difference plate), 11...liquid crystal display panel, 206...diffuser, 21...λ / 4 plate (polarization conversion element), 300...reflector, 213...λ / 2 plate, 306...reflective light guide, 307...reflective surface, 3 08...sub-reflector, 331...space floating image, 332...ghost image, 333...ghost image, 334...image light control sheet, 336...light transmitting section, 337...light absorbing section, 340...first distance measuring device, 341...second distance measuring device, 350...casing, 360...optical path folding mirror, 361...capacitive touch panel, 362...support member, 81...optical element, 501...polarization conversion element, 503...unit, 507...light shielding wall, 401, 402...light shielding plate, 320...substrate, Ph...object

Claims

1. A space floating image display system, a display panel for displaying images; a light source device that supplies light to the display panel; an optical plate that reflects image light from the display panel and displays a real image floating in space in the air using the reflected light; a sensor that divides an area including the floating image into a matrix and senses the divided area; The sensing areas sensed by the sensors are arranged in a matrix pattern in directions parallel to the long and short sides of the floating image. A floating video display system.

2. 2. The space floating image display system according to claim 1, The matrix-shaped sensing area is divided into a plurality of sections in both the vertical and horizontal directions as viewed from the user. A floating video display system.

3. 2. The space floating image display system according to claim 1, The sensing results of the sensors are used to detect user operations on the corresponding sensing areas. A floating video display system.

4. 2. The space floating image display system according to claim 1, The light source device is a point or surface light source; a reflector that reflects light from the light source; a light guide that guides the light from the reflector toward the display panel. A floating video display system.

5. 5. The space floating image display system according to claim 4, The reflecting surface of the reflector has an asymmetric shape with respect to the optical axis of the light emitted from the light source. A floating video display system.

6. 5. The space floating image display system according to claim 4, The light guide is a reflective light guide that guides light by reflection on a reflective surface on the surface of the light guide. A floating video display system.

7. 5. The space floating image display system according to claim 4, a diffusion plate that diffuses light from the light guide; and side walls arranged to sandwich a space between the light guide and the diffusion plate. A floating video display system.

8. 5. The space floating image display system according to claim 4, The reflector is made of a plastic material, a glass material, or a metal material. A floating video display system.

Images