Spatial floating image information display system and three-dimensional sensing device used therefor

Abstract

To provide a method for operating a displayed space image with high visibility and high accuracy in a three-dimensional manner and a space floating information display system or a space floating video display device for displaying an appropriate video with reduced erroneous detection.SOLUTION: A space floating video information display system comprises a video display device, a light source device and a recursive reflection member for reflecting video light from the video display device and displaying a space floating video of a real image in the air with the reflected light. The light source device includes optical means for reducing a divergent angle of a divergent light from a point-like or plane-like light source and a planar light source including a reflection plane by which the divergent light is reflected and propagated to the video display device, and a part of the divergent angle of light flux emitted from the planar light source is adjusted in accordance with the shape and surface roughness of the reflection plane provided in the planar light source. A plurality of TOF systems each including a light source and a light-receiving unit are disposed in a matrix shape, the TOF system comprises a first range finding device for dividing a space including the space floating video into a plurality of regions and sensing them, and the space floating video is irradiated with divergent light from the light source.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a spatial floating video information display system and a three-dimensional sensing device used therefor.

Background Art

[0002] As a spatial floating information display system, a video display device that directly displays a video toward the outside and a display method that is displayed as a spatial screen are already known. Also, a detection system for reducing false detection of operations on the operation surface of a displayed spatial image is disclosed in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as a method for three-dimensionally operating a spatial floating video information display system or a spatial image of the prior art with high precision, an optimization technique for the design including the light source of the video display device that is the video source of the spatial floating video has not been considered.

[0005] An object of the present invention is to provide a technique capable of displaying a suitable video with high visibility (apparent resolution and contrast) and reducing false detection in a spatial floating information display system or a spatial floating video display device, and accurately three-dimensionally operating a displayed spatial image.

Means for Solving the Problems

[0006] To solve the above problems, for example, the configuration described in the claims is adopted. This application includes a plurality of means for solving the above problems, and as an example thereof, a spatial floating image display device is given below. A spatial floating image display device as an example of this application includes an image display device for displaying an image, a light source device, and a retroreflective member that reflects the image light from the image display device and displays a real image spatial floating image in the air by the reflected light. The light source device includes an optical means for reducing the divergence angle of the divergent light from a point-like or planar light source, and a surface light source provided with a reflecting surface for reflecting the divergent light and propagating it to the image display device, and a part of the divergence angle of the light beam emitted from the surface light source is adjusted by the shape and surface roughness of the reflecting surface provided on the surface light source. A plurality of TOF (Time of Flight) systems each including a light source and a light receiving part are arranged in a matrix, and the divergent light from the light source of the TOF system includes a first distance measuring device that divides the space including the spatial floating image into a plurality of regions and performs sensing, and the light source light of the TOF system is irradiated toward the spatial floating image in the air.

Advantages of the Invention

[0007] According to the present invention, it is possible to preferably display spatial floating image information, and a spatial floating information display system or a spatial floating image display device having a three-dimensional sensing function with less false detection can be realized. Other problems, configurations, and effects than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the content of the embodiments (hereinafter also referred to as "the present disclosure") described below. The present invention also extends to the scope of the technical idea described in the spirit of the invention or the scope of the claims or equivalents thereof. In addition, the configurations of the embodiments (examples) described below are merely illustrative, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification.

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

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

[0012] According to the following embodiments, for example, high-resolution video information can be displayed in a state of floating in space on the glass surface of a show window or on a light-transmissive plate material. At this time, by reducing the divergence angle of the emitted video light, that is, making it an acute angle, and further aligning it with a specific polarization, only the regular reflected light can be efficiently reflected to the retroreflective member. For this reason, the utilization efficiency of light is high, and it is possible to suppress ghost images generated in addition to the main space-floating image, which has been a problem in the conventional retroreflective method, and a clear space-floating video can be obtained.

[0013] In addition, an apparatus including the light source of the present disclosure can provide a novel and highly usable spatial floating video information display system capable of significantly reducing power consumption. Further, according to the technology of the present disclosure, for example, a floating video information display system for a vehicle capable of displaying a so-called unidirectional spatial floating video that is visible outside the vehicle through a shield glass including a front glass, a rear glass, or a side glass of the vehicle can be provided.

[0014] On the other hand, in a conventional spatial floating video information display system, an organic EL panel or a liquid crystal display panel (liquid crystal panel or display panel) is combined with a retroreflective member as a high-resolution color display video source. In a spatial floating video display device according to the prior art, since video light diffuses at a wide angle, in addition to the reflected light regularly reflected by the retroreflective member which is the first embodiment constituted by the polyhedron shown in FIG. 2, as shown in FIG. 2(C), a ghost image is generated by the video light incident obliquely on the retroreflective member 2a, deteriorating the image quality of the spatial floating video. Further, in a spatial floating video display device according to the prior art, as shown in FIG. 2, in addition to a normal spatial floating video, a plurality of ghost images corresponding to the number of reflecting surfaces are generated. For this reason, the same spatial floating video which is a ghost image is viewed not only by viewers but also by others, posing a major problem from the viewpoint of security.

[0015] <First Configuration Example of Spatial Floating Video Information Display System> FIG. 1(A) is a diagram showing an example of the usage form of the spatial floating video information display system of the present disclosure. Further, FIG. 1(A) is a diagram for explaining the overall configuration of the spatial floating video information display system in the present embodiment. Referring to FIG. 1(A), for example, in a store or the like, a space is partitioned by a show window (also referred to as a “window glass”), which is a translucent member such as glass, 105. According to the spatial floating information display system of the present disclosure (hereinafter also referred to as “this system”), it is possible to display a floating video in one direction with respect to the outside of the store (space) through such a transparent member.

[0016] Specifically, according to this system, light with a sandwiching angle directivity characteristic and a specific polarization is emitted as a video light beam from the video display device (display device) 1, once enters the retroreflective member 2, is retroreflected, passes through the windshield 105, and forms a real image, i.e., an aerial image 3 (spatial floating image 3), outside the store. In Fig. 1(A), the inside (inside the store) of the transparent member (here, the windshield) 105 is taken as the depth direction, and the outside of the windshield 105 (e.g., the sidewalk) is shown in the foreground. On the other hand, means for reflecting a specific polarization is provided on the windshield 105, and the video light beam can also be reflected by such means to form an aerial image at a desired position inside the store.

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

[0018] Among these, the video signal receiving unit, for example, plays a role of corresponding to a wired input signal through an input interface such as HDMI (High-Definition Multimedia Interface (registered trademark)), and corresponding to a wireless input signal such as Wi-Fi (registered trademark) (Wireless Fidelity). Also, the video signal receiving unit can function independently as a video receiving and displaying device. Further, the video signal receiving unit can also display video information from a tablet, a smartphone, etc. Furthermore, the video signal receiving unit can connect a processor (arithmetic processing device) such as a stick PC as needed. In this case, the entire video signal receiving unit can be provided with capabilities such as calculation processing and video analysis processing.

[0019] FIG. 2 is a diagram showing an example of the main configuration and the retroreflective portion configuration of the spatial floating video information display system of the present disclosure. Using FIG. 2, the configuration of the spatial floating video information display system will be described more specifically. As shown in FIG. 2(A), a video display device 1 that diverges video light of a specific polarization at an included angle is provided in an oblique direction of a transmissive plate (hereinafter referred to as a "transparent member") 100 having light transmissivity such as glass. The video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having diffusion characteristics at an included angle.

[0020] The video light of a specific polarization from the video display device 1 is reflected by a polarization separation member 101 having a film that selectively reflects the video light of the specific polarization provided on the transparent member 100 (in the figure, the polarization separation member 101 is formed in a sheet shape and adhered to the transparent member 100), and enters the retroreflective member 2. A λ / 4 plate 21 is provided on the video light incident surface of the retroreflective member. The video light is polarization-converted from a specific polarization to the other polarization by passing through the λ / 4 plate 21 twice, when entering and exiting the retroreflective member.

[0021] Here, since the polarization separation member 101 that selectively reflects the video light of a specific polarization has the property that the polarization of the other polarization after polarization conversion is transmitted, the video light of the specific polarization after polarization conversion passes through the polarization separation member 101. The video light that has passed through the polarization separation member 101 forms a spatial floating video 3, which is a real image, outside the transparent member 100.

[0022] Note that the light that forms the aerial floating video 3 is a collection of light rays that converge from the retroreflective member 2 to the optical image of the aerial floating video 3, and these light rays continue to travel straight even after passing through the optical image of the aerial floating video 3. Therefore, the aerial floating video 3 is a video with high directivity, different from the diffused video light formed on a screen by a general projector or the like.

[0023] Therefore, in the configuration of FIG. 2, when the user views from the direction of arrow A, the floating image 3 in the air is viewed as a bright image. However, when another person views from the direction of arrow B, the floating image 3 in the air cannot be viewed as an image at all. This characteristic is very suitable when adopted in a system for displaying images that require high security or highly confidential images that need to be concealed from the person facing the user.

[0024] Depending on the performance of the retroreflective member 2, the polarization axes of the image light after reflection may become uneven. In this case, some of the image light with uneven polarization axes is reflected by the polarization separation member 101 described above and returns to the image display device 1. This part of the image light is retroreflected on the image display surface of the liquid crystal display panel 11 constituting the image display device 1, and may cause a reduction in the image quality of the floating image in space by generating a ghost image.

[0025] Therefore, in the present embodiment, an absorption type polarizing plate 12 is provided on the image display surface of the image display device 1. The absorption type polarizing plate 12 can suppress retroreflection by transmitting the image light emitted from the image display device 1 through the absorption type polarizing plate 12 and absorbing the reflected light returning from the polarization separation member 101 with the absorption type polarizing plate 12. Therefore, according to the present embodiment using the absorption type polarizing plate 12, it is possible to prevent or suppress a reduction in image quality due to a ghost image of the floating image in space.

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

[0027] Next, as a typical retroreflective member 2 in FIG. 2(B), the surface shape of the retroreflective member manufactured by Nippon Carbide Industries Co., Ltd. used in this study is shown. The light rays incident inside the regularly arranged hexagonal prisms are reflected by the wall surfaces and the bottom surfaces of the hexagonal prisms and exit as retroreflected light in the direction corresponding to the incident light, displaying a spatial floating image that is a real image based on the image displayed on the video display device 1. The resolution of this spatial floating image depends greatly on the outer shape D and pitch P of the retroreflective portion of the retroreflective member 2 shown in FIG. 2(B) in addition to the resolution of the liquid crystal display panel 11. For example, when using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is about 80 μm, for example, if the diameter D of the retroreflective portion is 240 μm and the pitch is 300 μm, one pixel of the spatial floating image corresponds to 300 μm. Therefore, the effective resolution of the spatial floating image is reduced to about 1 / 3. Therefore, in order to make the resolution of the spatial floating image equivalent to that of the video display device 1, it is desirable to make the diameter and pitch of the retroreflective portion closer to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moiré due to the pixels of the retroreflective member and the liquid crystal display panel, it is good to design by deviating the respective pitch ratios from an integral multiple of one pixel. Also, it is good to arrange the shape so that none of the sides of the retroreflective portion overlap any of the sides of one pixel of the liquid crystal display panel.

[0028] On the other hand, in order to manufacture the retroreflective member at a low cost, it is good to use a roll press method for molding. Specifically, it is a method of aligning the retroreflective portions and shaping them on a film. The inverse shape of the shape to be shaped is formed on the roll surface, an ultraviolet curable resin is applied on the fixing base material, and it is passed between the rolls to shape the required shape and irradiate it with ultraviolet rays to cure it, obtaining the retroreflective member 2 with the desired shape.

[0029] Next, Fig. 3(B) shows the surface shape for explaining the operating principle of the retroreflective member manufactured by Askanet Co., Ltd. used in this study as another typical retroreflective member 330. Light rays incident inside a regularly arranged four-sided structure are reflected by two of the four walls of the tetrahedron and exit as retroreflected light in a direction corresponding to the incident light, displaying a spatial floating image 331 (see Fig. 3(A)), which is a real image based on the object Ph. Similar to the above-described first retroreflective member, the resolution of this spatial floating image also greatly depends on the outer diameter D and pitch P of the retroreflective portion. For example, when using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is about 80 μm, if the diameter D of the retroreflective portion is 120 μm and the pitch is 150 μm, for example, one pixel of the spatial floating image corresponds to 150 μm. Therefore, the effective resolution of the spatial floating image is reduced to about 1 / 2. Here, in order to make the resolution of the spatial floating image equivalent to that of the video display device 1, it is desirable to make the diameter and pitch of the retroreflective portion closer to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moiré due to the retroreflective member and the pixels of the liquid crystal display panel, as described above, it is advisable to design by deviating the respective pitch ratios from an integer multiple of one pixel. Also, it is advisable to arrange the shape so that none of the sides of the retroreflective portion overlap with any of the sides of one pixel of the liquid crystal display panel.

[0030] Note that the light forming the spatial floating image 331 is a set of light rays converging from the retroreflective member 330 to the optical image of the spatial floating image 331, and these light rays continue to travel straight even after passing through the optical image of the spatial floating image 331. Therefore, unlike the diffused video light formed on a screen by a general projector or the like, the spatial floating image 331 is a video with high directivity.

[0031] In the configurations of FIGS. 3(A) and 3(B), when the user views from the direction of arrow A, the spatially floating image 331 is viewed as a bright image. However, when another person views from the direction of arrow B, the spatially floating image 331 cannot be viewed as an image at all. This characteristic, similar to the airborne floating image using the first retroreflective member described above, is very suitable when adopted in a system for displaying an image that requires high security or an image with high confidentiality that needs to be concealed from the person facing the user.

[0032] In the second retroreflective member 330, the object light after reflection enters the retroreflective member 330 as R0 from one side as shown in FIG. 3(B) and is reflected by two reflecting surfaces provided on the four wall surfaces constituting the retroreflective member 330, and a real floating image in space is formed on the other side. At this time, due to the abnormal lights R1 and R2 generated by the two reflecting surfaces, the ghost images 332 and 333 shown in FIG. 3(A) are generated. Therefore, the image quality of the spatially floating image is degraded.

[0033] As described above, while the first retroreflective member generates ghost images according to the number of reflecting surfaces, the second retroreflective member that generates ghost images only in two specific directions depending on the incident angle of the object light is less affected by ghost images and enables high-quality spatial video display. Therefore, the spatial floating image display device described below will be described focusing on the method using the second retroreflective member described above.

[0034] <Technical means for reducing ghost images> In order to realize a high-quality spatial video display device with reduced ghost images as a spatial floating image display device, specifically, in order to control the divergence angle of the video light from the liquid crystal panel as a video display element and bend it in a desired direction, it is advisable to provide a video light control sheet on the exit surface of the liquid crystal panel. Furthermore, a reflected light control sheet is provided on the light exit surface or the light incident surface or both surfaces of the retroreflective member to absorb the abnormal lights R1 and R2 that generate ghost images.

[0035] Figure 4 shows a specific method of applying the video light control sheet 334 to the spatial video display device. The video light control sheet 334 is provided on the light-emitting surface of the liquid crystal panel 11 which is a video display element. At this time, in order to reduce moiré generated by interference due to the pitch of the pixels of the liquid crystal panel 11 and the transmissive portions and light absorption portions of the video light control sheet 334, the following two methods shown in (1) and (2) are effective.

[0036] (1) The vertical stripes generated by the transmissive portions and light absorption portions of the video light control sheet 334 are arranged with an inclination of θ0 with respect to the arrangement of the pixels 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 video light control sheet 334 is B, this ratio (B / A) is selected so as to be outside an integral multiple.

[0038] One pixel of the liquid crystal panel is composed of three pixels of RGB arranged in parallel and is generally square. Therefore, it is not possible to suppress the occurrence of moiré over the entire screen. For this reason, it was experimentally determined that the inclination θ0 shown in (1) should be optimized within the range of 5 degrees to 25 degrees so that the generation position of moiré can be intentionally shifted to a place where the spatial floating video is not displayed. Although the liquid crystal panel has been described as a material for reducing moiré, moiré generated between the retroreflective member 103 and the video light control sheet 334 is due to both being stripe-like structures. Therefore, as shown in Figure 4, by optimally inclining the video light control sheet 334 with respect to the X axis, it is possible to reduce large-scale moiré with a low frequency that can be visually recognized even with a long wavelength.

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

[0040] Also, as described above, when using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel as the video display device 1, even if one pixel (one triplet) (A in the figure) is about 80 μm, for example, if the pitch B consisting of a transmission part d2 of 300 μm and a light absorption part d1 of 40 μm of the video light control sheet 334 is 340 μm, it is possible to control sufficient transmission characteristics and the diffusion characteristics of the video light from the video display device that causes abnormal light, and reduce the ghost images generated on both sides of the spatial floating image. At this time, if the thickness of the video control sheet is set to be 2 / 3 or more of the pitch B shown in Fig. 5(A), the ghost reduction effect will be significantly improved.

[0041] Fig. 5(B) is a vertical cross-sectional view of the retroreflective member of the present disclosure in which the video light control sheet 334 is disposed on the video light exit surface of the retroreflective member 103. The video light control sheet 334 is configured by alternately arranging a light transmission part 336 and a light absorption part 337, and is inclinedly arranged with an inclination angle θ1 in accordance with the exit direction of the retroreflected light. As a result, the abnormal light generated due to the above-described retroreflection can be absorbed, and on the other hand, the normal reflected light can be transmitted without loss. When using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel, even if one pixel (one triplet) (A in the figure) is about 80 μm, for example, if the pitch B consisting of a transmission part d2 of 400 μm and a light absorption part d1 of 20 μm of the retroreflective part is 420 μm, it is possible to control sufficient transmission characteristics and the diffusion characteristics of the video light from the video display device that causes abnormal light in the retroreflective member, and reduce the ghost images generated on both sides of the spatial floating image.

[0042] The above-described video light control sheet 334 also helps to improve the reliability of the components because it prevents external light from the outside from entering the spatial floating video display device. As this video light control sheet, for example, the viewing angle control film (VCF) of Shin-Etsu Polymer Co., Ltd. is suitable. Since its structure is a sandwich structure with transparent silicon and black silicon alternately arranged and a synthetic resin disposed on the light input / output surface, the same effect as the external light control film of this embodiment can be expected.

[0043] <Technical means for sensing spatial floating video> In order for a viewer (operator) to be bi-directionally connected to an information system via a spatial floating image display device, the sensing technology for pseudo-operating a spatial floating image will be described below. FIG. 6(A) is a principle diagram for explaining the first sensing technology. The spatial floating image FI is divided into a plurality of areas, in this example, into 12 areas, and a first distance measuring device 340 incorporating a TOF (Time of Flight) system corresponding to each area is provided. An LED (Light Emitting Diode) that emits near-infrared light, which is a light source, is caused to emit light in synchronization with the signal of the system. On the light emission side of the LED, an optical element for controlling the divergence angle is provided, and a pair of highly sensitive avalanche diodes with picosecond time resolution are used as light receiving elements, and are arranged in four vertical rows and three horizontal rows so as to correspond to 12 areas. The LED, which is a light source, emits light in synchronization with the signal from the system, and the phase (Δt in FIG. 8A) is shifted by the time from when the light is reflected by the object to be measured (the tip of the viewer's finger) until it returns to the light receiving part.

[0044] In this embodiment, the sensing units 1 to 12 in FIG. 8A are described as an example corresponding to TOF1 to 12 in FIG. 8B. The arithmetic unit of the sensing system receives the signal from the system and the signal generated by the avalanche diode, which is the light receiving part, and calculates the distance to the object by calculating the phase shift from the received signals. On the other hand, the direction of movement of the object can be recognized by recognizing which area of the 12 areas has been passed through in each measurement layer (from a3 to a1), and calculating the movement time of each measurement layer by the method described above, so that it can be recognized as a system. The light emission timing of the LED for each of the 12 measurement areas and the light reception timing of the light receiving element are shown in FIG. 8A. The individual data is normalized by delaying the light emission timing of the LED for each area.

[0045] Actually, when the viewer (operator) extends a finger toward the spatial floating image FI to bidirectionally connect to the information system via the spatial floating image display device, the contact position with the spatial floating image FI is calculated and obtained from the first sensing signal S1 sensed in the area on the sensing surface a3 farthest from the airborne floating image FI, the second sensing signal S2 sensed in a specific area of the sensing surface a2, and the third sensing signal S3 sensed in a specific area of the third sensing surface a1, based on the moving direction of the finger and the time difference across each sensing surface. To obtain even more accurate position information, a position sensing surface a0 farther from the spatial floating image FI is set, and when it is detected that the finger has passed through the spatial floating image FI as an end signal, the contact point with the spatial floating image is obtained as three-dimensional coordinates from its coordinates and the two aforementioned sensing signals.

[0046] Next, the second sensing technology will be described. As shown in the lower part of Fig. 6(B), when the viewer touches the desired coordinates (position) of the spatial floating image and then retracts the finger, the third sensing signal S3 sensed on the third sensing surface a1, the second sensing signal S2 sensed on the second sensing surface a2, and further the first sensing signal S1 sensed on the first sensing surface a1 are sequentially transmitted to the processing circuit of the sensing system for calculation processing, whereby it is recognized on the system that the viewer's finger has left the specific coordinates of the spatial floating image.

[0047] The high-precision sensing technology for pseudo-operating the spatial floating image will be described below so that the viewer (operator) can be bidirectionally connected to the information system via the spatial floating image display device.

[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 in addition to the first distance measuring device 340, a second distance measuring device 341 is installed in parallel to realize a more accurate system. As described above, the first distance measuring device 340 divides the spatial floating image FI into a plurality of areas (12 areas in the embodiment) and incorporates a TOF (Time of Flight) system corresponding to each area.

[0049] On the other hand, the second distance measuring device 341 has a two-dimensional image sensor. For example, in the case of a 1 / 4-inch CMOS sensor for sensing camera applications, the aspect ratio is generally 3:4. Therefore, in this embodiment, the first distance measuring device 340 also divides the sensing area into three vertical divisions and four horizontal divisions. Also, although a resolution of about 1 million pixels provides sufficient resolution, unlike a normal camera system, since there is no need to provide an RGB color separation filter, miniaturization and high sensitivity can be achieved even with the same number of pixels as in the prior art. In addition, in the configuration of this embodiment, since the sensitivity to near-infrared light is high, the object to be distance-measured (the tip of the viewer's finger) by the light source light of the TOF system of the first distance measuring device 340 is illuminated at a timing determined for each area, so the detection accuracy is significantly improved.

[0050] The system described above is shown as a block diagram in FIG. 8B. In the example of FIG. 8B, it includes a first sensing unit as an example of the first distance measuring device 340. Also, it includes a second sensing unit having a CMOS sensor as an example of the second distance measuring device 341. Furthermore, it includes an arithmetic unit of a sensing system that performs arithmetic operations based on the sensing results of the first sensing unit and the second sensing unit. In the example of this figure, for example, there are 12 TOF sensors (TOF1 to 12 shown in FIG. 8B), and the sensing surfaces a1, a2, and a3 are each divided into 12 parts, and any one of the divided areas is sensed. Even if the depths of the sensing surfaces a1, a2, and a3 are different, the areas at corresponding positions may be sensed by the same TOF sensor. In this case, the space including the sensing surfaces a1, a2, and a3 is divided into three vertical divisions and four horizontal divisions, that is, a total of 12 divisions, and each of the divided spaces is sensed by the corresponding TOF sensor. In this way, accurate three-dimensional sensing can be realized with a small number of TOF sensors. Note that the space including the sensing surfaces a1, a2, and a3 may be divided into three parts in the depth direction corresponding to the sensing surfaces a1, a2, and a3, and further divided into three vertical divisions and four horizontal divisions respectively, and may be configured with a total of 36 TOF sensors corresponding to the total of 36 divided spaces.

[0051] As shown in Fig. 7(B), in the spatial floating image display device using the second sensing technology, when the viewer (operator) extends a finger toward the spatial floating image FI to connect to the information system bidirectionally, in addition to the three-dimensional information by the first distance measuring device 340 described above, the planar resolution of the sensing surface b3 of the second distance measuring device 341 corresponding to the sensing surface a3 that is the farthest from the airborne floating image FI can be increased with high precision according to the resolution of the CMOS sensor being used. Similarly, a sensing surface b2 corresponds to the sensing surface a2, and a sensing surface b1 corresponds to the sensing surface a1, and a sensing system with significantly improved resolution in the planar direction can be realized. At this time, the moving direction of the object (the tip of the viewer's finger) is obtained by calculating the contact position with the spatial floating image FI from the time difference across each sensing surface.

[0052] To obtain even more accurate position information, a sensing surface a0 is set at a position farther from the spatial floating image FI, and when it is detected that the finger has passed through the spatial image FI as an end signal, the contact point to the spatial floating image can be obtained as a three-dimensional coordinate with higher fineness from its coordinates and the two aforementioned sensing signals. Also, if the frame rate of the CMOS sensor is increased from 1 / 20 second to 1 / 30 second, 1 / 120 second, the amount of planar information captured per unit time increases in addition to the detection accuracy in the planar direction, so the resolution is significantly improved. At this time, the position information by the first sensing technology is synchronized by the synchronization signal supplied from the information system.

[0053] Furthermore, as shown in the lower part of Fig. 7(B), when the viewer returns the finger after touching the desired coordinate (position) of the spatial floating image, similar to the first sensing technology described above, the first sensing signal S1 sensed on the first sensing surface a1 is sequentially transmitted to the processing circuit of the sensing system by the third sensing signal S3 sensed on the third sensing surface a1 and the second sensing signal S2 sensed on the second sensing surface a2 and subjected to calculation processing, so that it is recognized on the system that the viewer's finger has left the specific coordinate of the spatial floating image.

[0054] For the LED light source used in the above-mentioned solid TOF sensor, it is advisable to use near-infrared light with high light energy in a region beyond the visible light range (380 (nm) to 780 (nm)) that cannot be visually recognized by the naked eye to prevent a decrease in accuracy against external light (sunlight) of the distance measuring device. For example, it is advisable to use light with a wavelength of 920 (nm) with less energy in the spectral irradiance of sunlight shown in FIG. 9.

[0055] <Second Configuration Example of Spatial Floating Video Information Display System> FIG. 11 is a diagram showing the main configuration of a spatial floating video information display system according to an embodiment of the present invention. This spatial video information display system is suitable for a viewer to observe a spatial floating video from an obliquely upward direction. The video display device 1 includes a liquid crystal display panel 11 as a video display element and a light source device 13 that generates light of a specific polarization having a diffusion characteristic with a sandwiching angle. The liquid crystal display panel 11 can be composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches.

[0056] The video light from the liquid crystal display panel 11 is emitted toward the retroreflective member (retroreflective portion or retroreflective plate) 330. Light from the light source device 13 with a narrow divergence angle, which will be described later, is incident on the liquid crystal panel to generate a video light beam φ1 with a narrow divergence angle and is incident on the retroreflective member 330 to obtain a spatial floating video 3. The spatial floating video 3 is formed at a symmetric position of the video display device 1 with the retroreflective member 330 as a symmetric plane. In order to eliminate the ghost image generated at this time and obtain a high-quality spatial floating video 3, it is advisable to provide a video light control sheet 334 on the emission side of the liquid crystal panel 11 to control the diffusion characteristics in unnecessary directions.

[0057] Furthermore, as shown in FIG. 10, since the reflectance of the reflection member such as the retroreflective member for the video light from the liquid crystal panel 11 can be increased in principle, it is preferable to use the S-polarized wave. On the other hand, when the viewer uses polarized sunglasses, there is a problem that the aerial floating image is reflected or absorbed by the polarized sunglasses. As a countermeasure, it is preferable to provide a cancellation element 339 that optically converts a part of the video light of a specific polarization to the other polarization to pseudo-convert it to natural light. With such a configuration, even when the viewer uses polarized sunglasses, a good aerial floating video can be viewed.

[0058] Examples of commercially available products of the polarization cancellation element include, for example, Cosmo Shine SRF (manufactured by Toyobo Co., Ltd.) and polarization cancellation adhesive (manufactured by Nagase Sangyo Co., Ltd.). In the case of Cosmo Shine SRF (manufactured by Toyobo Co., Ltd.), by attaching an adhesive on the image display device, the reflection at the interface can be reduced and the luminance can be improved. In the case of the polarization cancellation adhesive, it can be used by bonding a colorless transparent plate and the image display device via the polarization cancellation adhesive. Further, as shown in FIG. 11, a video light control sheet 334 is also provided on the video emission surface of the retroreflective member 330 to eliminate ghost images generated on both sides of the normal image of the aerial floating video 3 by unnecessary light by the video light control sheet 334. In this embodiment, the retroreflective member 330 is inclined (θ1) with respect to the horizontal axis, and the aerial floating video 3 is generated substantially perpendicular to the horizontal axis.

[0059] Also, in this embodiment, as shown in FIG. 11, a first distance measuring device 340 is attached to form a system in which the viewer can access the aerial floating video. At this time, it is preferable to appropriately select the attachment position and the viewing angle θ3 of the distance measuring device 340 so that the size of the aerial floating video can be sufficiently covered. From the TOF sensor of the distance measuring device 340, as shown in FIGS. 6 and 7, by using a distance measuring system divided into a plurality of areas, the resolution for each sensing area is increased. Furthermore, a second sensing technique using a CMOS sensor (the second distance measuring device 341 is not shown in FIG. 11) can also be used in combination, and in this case, the detection accuracy can be further improved.

[0060] In addition, in this embodiment, by using a light source that emits visible light having a narrow-angle directivity characteristic and arranging the first distance measuring device and the second distance measuring device on the main body side, it is possible to eliminate the influence on the sensing accuracy of the video light forming the spatial floating image.

[0061] <Third Configuration Example of Spatial Floating Image Information Display System> FIG. 12 is a diagram showing another example of the spatial floating image information display system. This spatial video information display system is suitable for a viewer to observe the spatial floating image from an obliquely downward direction. The video display device 1 includes a liquid crystal display panel 11 as a video display element and a light source device 13 that generates light of a specific polarization having a sandwiching angle diffusion characteristic.

[0062] The liquid crystal display panel 11 can be composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. The video light from the liquid crystal display panel 11 is reflected back by an optical path folding mirror (also referred to as a "folding mirror") 360 and emitted toward a retroreflective member (retroreflective portion or retroreflective plate) 330. The light from the light source device 13 with a narrow divergence angle described later is incident on the liquid crystal panel 11 to generate a video light beam φ1 with a narrow divergence angle, and the video light beam φ1 is incident on the retroreflective member 330 to obtain a spatial floating image. The spatial floating image is formed at a symmetric position of the video display device 1 with the retroreflective member 330 as the symmetry plane. In this embodiment, the distance from the video display device 1 to the retroreflective member 330 can be extended by the folding mirror 360, and the spatial floating image can be formed at a position away from the retroreflective member 330. Further, in this embodiment, as described below, there is also an effect of enlarging the spatial floating image in the vertical direction.

[0063] Using FIG. 12, the folded mirror reflection image 360a will be described. In this embodiment, the folded mirror 360 is disposed at an inclination with respect to the video light beam φ1 from the video display device 1, and by making the incident angle θ1 of the video light greater than 45 degrees, an enlarged folded mirror reflection image 360a can be obtained. For example, if the folded mirror 360 is disposed such that the light incident angle is 60 degrees, it can be visually recognized that the vertical dimension of the image of the folded mirror reflection image 360a is enlarged approximately twice with respect to the vertical dimension of the image displayed on the liquid crystal panel. Needless to say, in this case, the luminance of the secondary video source becomes 1 / 2. Further, it goes without saying that the same magnifying effect can be obtained even if the folded mirror 360 is tilted in the depth direction of the figure in FIG. 12. On the other hand, for the displayed video, it is advisable to perform image processing such as converting the aspect ratio of the image so that there is no visual problem even if the pixels are stretched in the vertical direction.

[0064] In order to eliminate the ghost image generated in the spatial floating image 3 and obtain a high-quality spatial floating image 3, similar to the second embodiment, a video light control sheet 334 may be provided on the emission side of the liquid crystal display panel 11 to control the diffusion characteristics in unnecessary directions. On the other hand, by providing the video light control sheet 334 also on the video emission surface of the retroreflective member 330, the ghost images generated on both sides of the normal image of the spatial floating image 3 due to unnecessary light may be eliminated. The retroreflective sheet 330 can generate the spatial floating image 3 substantially perpendicular to the horizontal axis by tilting (θ1) with respect to the horizontal axis. A ranging device 340 is attached to form a system that allows the viewer to access the spatial floating image. It is advisable to appropriately select the attachment position and the viewing angle θ3 of the ranging device 340 so as to sufficiently cover the size of the spatial floating image 3.

[0065] <Fourth Configuration Example of Spatial Floating Image Information Display System> FIG. 13 is a diagram showing another example of a spatial floating video information display system. This spatial video information display system is suitable for a viewer to observe a spatial floating video from an obliquely upward direction. The video display device 1 includes a liquid crystal display panel 11 as a video display element and a light source device 13 that generates light of a specific polarization having a diffusion characteristic with a sandwiching angle. The liquid crystal display panel 11 can be composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. The video light from the liquid crystal display panel 11 is reflected by the optical path folding mirror 360 and emitted toward the retroreflective member (retroreflective part or retroreflective plate) 330. The liquid crystal display panel 11 is made to receive light from the light source device 13 with a narrow divergence angle, which will be described later, to generate a video light beam φ1 with a narrow divergence angle and make it incident on the retroreflective member 330 to obtain a spatial floating image. The spatial floating image is formed at a symmetric position of the video display device 1 with the retroreflective member 330 as the symmetry plane. In this embodiment, similar to the third embodiment described above, by interposing the folding mirror 360, the distance from the video display device 1 to the retroreflective member 330 can be extended, and the spatial floating video can be imaged at a position away from the retroreflective member 330. Furthermore, as will be described below, there is also an effect of vertically enlarging the spatial floating video 3.

[0066] The folded mirror reflection image 360a will be described with reference to FIG. 13. By tilting the folding mirror 360 by θ2 with respect to the video light beam φ1 from the video display device 1 and making the incident angle θ0 of the video light greater than 45 degrees, an enlarged folded mirror reflection image 360a can be obtained. For example, if the folding mirror 360 is arranged so that the light ray incident angle is 60 degrees, it can be visually recognized that the vertical dimension of the image of the folded mirror reflection image 360a is enlarged to about twice the vertical dimension of the image displayed on the liquid crystal panel. At this time, for the displayed video, it is advisable to perform measures in the image processing aspect, such as converting the aspect ratio of the image, so that there is no visual problem even if the pixels are stretched in the vertical direction.

[0067] In the fourth embodiment, the video display device 1 is arranged above the floating image 3 in space. As a result, a system configuration can be realized in which the video light rays are incident on the retroreflective member 330 from obliquely above. Further, in order to form the floating image 3 in space almost perpendicularly to the set housing, the retroreflective member 330 can be arranged at an inclination (θ1) with respect to the bottom surface of the set housing. As a result, the deterioration of the image quality of the floating image 3 in space caused by external light entering the retroreflective member 330 and entering the housing can be avoided. In order to eliminate the ghost image generated in the floating image 3 in space and obtain a high-quality floating image 3 in space, similar to the second embodiment, a video light control sheet 334 may be provided on the emission side of the liquid crystal display panel 11 to control the diffusion characteristics in unnecessary directions. On the other hand, by providing a video light control sheet 334 also on the video emission surface of the retroreflective member 330, the ghost images generated on both sides of the normal image of the floating image 3 in space due to unnecessary light may be eliminated. The structures described above are arranged inside the housing 350 to prevent external light from entering the retroreflective member 330 and prevent the generation of ghost images.

[0068] Also in this embodiment, similar to the three floating image information systems in space described above, a ranging device 340 is mounted so that the viewer can access the floating image 3 in space. The mounting position of the ranging device 340 and the viewing angle θ3 may be appropriately selected so as to sufficiently cover the size of the floating image in space. Further, a capacitive touch panel 361 is fixed by a support member 362 and arranged between the floating image 3 in space and the retroreflective member 330. By using the third sensing technique using the capacitive touch panel 361 in combination with the first sensing technique, the detection accuracy can be further improved. The ranging device 340, the mounting position of the ranging device 340 and the viewing angle θ3 may be appropriately selected so as to sufficiently cover the size of the floating image 3 in space. Similarly, the size and mounting position of the capacitive touch panel 361 may be selected so as to sufficiently cover the floating image in space.

[0069] As a capacitive touch panel that captures highly accurate position information, a projection capacitive method is adopted. In this method, a capacitive touch panel is manufactured by patterning a transparent electrode ITO (Y-axis direction) having a fine line pitch and a transparent electrode (copper thin film) having a fine line pitch on both sides of a transparent glass substrate by photolithography etching. In this capacitive touch panel, when an object (the tip of the viewer's finger) approaches the above-mentioned transparent glass substrate, changes in capacitance are detected for each of the X-axis electrode and the Y-axis electrode, and the relative coordinates of the object are also obtained. The shorter the line pitch of the above-mentioned transparent electrode, the higher the resolution can be obtained. Further, according to the capacitive touch panel, multi-point detection is possible, and thus, simultaneous input with multiple fingers is possible.

[0070] <Method for displaying a spatially floating image> The inventors considered a method of displaying the spatially floating image displayed by the above-mentioned spatially floating image information display system so that the spatially floating image viewer can more vividly and pseudo-stereoscopically view the spatially floating image. The results are shown in FIGS. 14(A) and 14(B).

[0071] The first video display technical means is shown in FIG. 14(A). As shown in FIG. 14(A), for the spatially floating image, it is advisable to use about 80% of the video display area of the video display device 1 and always ensure a non-display (black display) area in the peripheral part or a part of the periphery. As a result, it was found that the viewer can perceive the sharpness of the floating image in the air based on the luminance ratio between this black display area (part) and the video display area (part).

[0072] In addition, as a display method, by effectively using the positions outside the center of the screen, shifting the center of the video from the center of the panel, and gradually moving the video 1361 from the lower right to the upper left of the screen (see the white arrow in Fig. 14A), for example, the sense of floating can be enhanced. Also, by gradually increasing the magnification of the video 1361 as it moves and showing it in a close-up view, the sense of floating can be enhanced. On the other hand, by gradually moving the video 1361 in the direction opposite to the white arrow in Fig. 14A, that is, from the upper left to the lower right of the screen, the sense of depth can be enhanced. Also, by gradually decreasing the magnification of the video 1361 as it moves and showing it in a long-shot view, the sense of floating can be enhanced.

[0073] Next, the second video display technical means is shown in Fig. 14(B). Here too, similar to the first video technical means, it is advisable to use approximately 80% of the video display area of the video display device 1 for the spatial floating video and always ensure a non-display (black display) area in the peripheral part or a part of the periphery. Alternatively, as shown in Fig. 14(B), a video 1362 that serves as a reference in the depth direction when the observer views the spatial floating video may be added. The video 1362 illustrated in Fig. 14(B) has a fixed position and a fixed size even when the video 1361 moves in the direction of the white arrow in Fig. 14(B), for example. By displaying such a fixed video 1362, the sense of popping out of the video 1361 in the spatial floating video is significantly improved because the video 1361 appears to be displayed relatively in front of the rear video 1362 (in other words, the reference video).

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

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

[0076] Then, through experiments, it was found that a contrast ratio value of 500 or more is desirable. For this reason, the inventors developed a light source device for a narrow divergence angle liquid crystal panel having a polarization conversion function as described later, thereby achieving low power consumption while ensuring high brightness and high contrast.

[0077] <Performance of liquid crystal panel> By the way, in a general TFT (Thin Film Transister) liquid crystal panel, the luminance and contrast performance vary depending on the characteristics of the liquid crystal and the polarizing plate according to the light emission direction. In the evaluation in the measurement environment shown in FIG. 17, the luminance and viewing angle characteristics in the vertical direction of the panel are better at an angle slightly deviated from the emission angle perpendicular to the panel surface (emission angle 0 degrees) as shown in FIG. 11 (in this embodiment, +5 degrees). This is because the light-twisting characteristic in the vertical direction of the liquid crystal does not become 0 degrees when the applied voltage is maximum.

[0078] On the other hand, the contrast performance in the vertical direction is excellent in the range from -15 degrees to +15 degrees in FIG. 19 showing the measurement results using Samples 1 to 3. When combined with the luminance characteristics, the most excellent characteristics can be obtained in the range of ±10 degrees centered on 5 degrees.

[0079] Also, the luminance and viewing angle characteristics in the horizontal direction of the panel are excellent at the emission angle perpendicular to the panel surface (emission angle 0 degrees) as shown in FIG. 20. This is because the light-twisting characteristic in the horizontal direction of the liquid crystal becomes 0 degrees when the applied voltage is maximum.

[0080] Similarly, regarding the contrast performance in the left-right direction, in FIG. 21 showing the measurement results using Samples 1 to 3, the range from -5 degrees to -10 degrees is excellent. When combined with the luminance characteristics, the most excellent characteristics can be obtained in the range of ±5 degrees centered around -5 degrees. Therefore, the emission angle of the video light emitted from the liquid crystal panel is such that light is incident on the liquid crystal panel from the direction in which the most excellent characteristics can be obtained by the light beam direction conversion means 204 provided in the light guide 203 of the light source device 13 described above, and the light is modulated by the video signal, which will improve the image quality and performance of the video display device 1.

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

[0082] <Method for Controlling Light Source Light> 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 the power consumption, in the video display device 1 configured to include the light source device 13 and the liquid crystal display panel 11, after the light is incident on the liquid crystal panel 11 from the light source device 13 at an incident angle that maximizes the characteristics of the liquid crystal panel 11, the video light beam modulated in luminance according to the video signal is emitted toward the retroreflective member 330. At this time, while miniaturizing the set volume of the spatial floating video information display system, the degree of freedom in arranging the liquid crystal panel 11 and the retroreflective member 330 is increased. Further, in order to form the floating video at a desired position and ensure optimal directivity after retroreflection, the following technical means are used.

[0083] On the image display surface of the liquid crystal panel 11, a transparent sheet made of optical components such as a Fresnel lens or a linear Fresnel lens is provided as a light direction conversion panel, and while imparting high directivity, the emission direction of the incident light beam to the retroreflective optical member 330 is controlled to determine the imaging position of the floating image in space. According to this configuration, as shown in FIG. 1, the image light from the image display device 1 can efficiently reach an observer outside the windshield 105 (for example, on the sidewalk) with high directivity (straightness) like laser light. As a result, a high-quality floating image can be displayed with high resolution, and at the same time, the power consumption of the image display device 1 including the light source device 13 can be significantly reduced.

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

[0085] Also, on the liquid crystal display panel frame attached to the upper surface of the case, the liquid crystal display panel 11 attached to the frame, and further, an FPC (Flexible Printed Circuits) (not shown in the figure) electrically connected to the liquid crystal display panel 11, etc. are attached and configured. That is, the liquid crystal display panel 11, which is a liquid crystal display element, together with the LED elements 14a and 14b, which are solid light sources, modulates the intensity of the transmitted light based on a control signal from a control circuit (not shown here) that constitutes an electronic device to generate a display image.

[0086] <Example 1 of the light source device of Example 1 of the 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 FIGS. 23(a) and (b) together with FIG. 22. FIGS. 22 and 23 show LEDs 14a and 14b that constitute the light source, and these are attached to the collimator 15 at predetermined positions. Note that each of these collimators 15 is formed of a light-transmissive resin such as acrylic. And as shown in FIG. 18(b) as well, this collimator 15 has an outer peripheral surface 156 having a conical convex shape obtained by rotating a parabolic cross-section, and at the central portion of its top (the side in contact with the LED substrate), it has a concave portion 153 formed with a convex portion (that is, a convex lens surface) 157.

[0087] Also, at the central portion of the flat surface portion (the side opposite to the above-mentioned top) of the collimator 15, it has a convex lens surface (or it may be a concave lens surface recessed inward) 154 that protrudes outward. Note that the parabolic surface 156 that forms the conical outer peripheral surface of the collimator 15 is set within a range of angles that can totally reflect the light emitted from the LEDs 14a and 14b in the peripheral direction inside it, or a reflecting surface is formed.

[0088] Also, the LEDs 14a and 14b are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the collimator 15 such that the LEDs 14a or 14b on its surface are respectively located at the central portions of the concave portions 153.

[0089] According to such a configuration, among the light emitted from the LED 14a or 14b, particularly the light emitted upward (in the right direction of the figure) from the central portion thereof, is condensed by the two convex lens surfaces 157 and 154 forming the outer shape of the collimator 15 and becomes parallel light. Further, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface of the collimator 15, and similarly, is condensed and becomes parallel light. In other words, according to the collimator 15 having a convex lens formed in its central portion and a parabolic surface formed in its peripheral portion, almost all of the light generated by the LED 14a or 14b can be taken out as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0090] Note that a polarization conversion element 21 is provided on the light emission 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-transmissive member (hereinafter, a parallelogram column) having a parallelogram cross section and a columnar light-transmissive member (hereinafter, a triangular column) having a triangular cross section, and is arranged in a plurality of arrays parallel to the plane orthogonal to the optical axis of the parallel light from the collimator 15. Further, a polarization beam splitter (hereinafter, abbreviated as "PBS film") 211 and a reflection film 212 are alternately provided at the interfaces between the adjacent light-transmissive members arranged in this array, and a λ / 2 phase plate 213 is provided on the emission surface from which the light incident on the polarization conversion element 21 and transmitted through the PBS film 211 is emitted.

[0091] A rectangular composite diffusion block 16 shown also in FIG. 23(a) is further provided on the emission surface of this polarization conversion element 21. That is, the light emitted from the LED 14a or 14b becomes parallel light by the action of the collimator 15, enters the composite diffusion block 16, is diffused by the texture 161 on the emission side, and then reaches the light guide 17.

[0092] The light guide 17 is a member formed of a light-transmissive resin such as acrylic into a rod shape with a substantially triangular cross section (see Fig. 23(b)). As is also apparent from Fig. 25, a light guide light incident portion (surface) 171 facing the light exit surface of the synthetic diffusion block 16 via the first diffusion plate 18a, a light guide light reflecting portion (surface) 172 forming an inclined surface, and a light guide light exit portion (surface) 173 facing the liquid crystal display panel 11, which is a liquid crystal display element, via the second diffusion plate 18b.

[0093] As shown in Fig. 23, which is a partially enlarged view of the light guide light reflecting portion (surface) 172 of the light guide 17, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a serrated shape. The reflecting surface 172a (the line segment rising to the upper right in the figure) forms an angle αn (n is a natural number, and in this example, for example, it is 1 to 130) with the horizontal plane indicated by the dashed-dotted line in the figure. As an example, here, αn is set to 43 degrees or less (however, 0 degrees or more).

[0094] The light guide light incident portion (surface) 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the light exit surface of the synthetic diffusion block 16 is diffused and incident via the first diffusion plate 18a, and as is apparent from the figure, it reaches the light guide light reflecting portion (surface) 172 while being slightly bent (deflected) upward by the light guide light incident portion (surface) 171, and is reflected here and reaches the liquid crystal display panel 11 provided on the upper light exit surface of the figure.

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

[0096] Note that in the light guide light reflecting portion (surface) 172, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. The illumination light beam is totally reflected on each reflecting surface 172a and directed upward. Further, a sandwiching angle diffuser plate is provided on the light guide light emitting portion (surface) 173, and the light enters the light direction conversion panel 54 that adjusts the directivity characteristics as a substantially parallel diffused light beam, and 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 emitting portion (surface) 173 and the liquid crystal display panel 11, but the same effect can be obtained even if it is provided on the emitting surface of the liquid crystal display panel 11.

[0097] <Example 2 of video display device> Subsequently, with reference to FIG. 24, another example (Example 3 of the video display device) of the specific configuration of the video display device 1 will be described. The light source device of this video display device 1 converts the diverging light beam (mixing P-polarized light and S-polarized light) from the LED into a substantially parallel light beam by the collimator 18, and reflects it toward the liquid crystal display panel 11 by the reflecting surface of the reflective light guide 304. The reflected light enters the reflective polarizing plate 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304.

[0098] In the reflective polarizing plate 49, a specific polarization wave (for example, P-polarized light) is transmitted and enters the liquid crystal display panel 11. The other polarization wave (for example, S-polarized light) is reflected by the reflective polarizing plate and goes back to the reflective light guide 304 again. The reflective polarizing plate 49 is installed with an inclination so as not to be perpendicular to the principal ray of the light from the reflecting surface of the reflective light guide 304, and the principal ray of the light reflected by the reflective polarizing plate 49 enters the transmissive surface of the reflective light guide 304.

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

[0100] At this time, the light that re-enters the reflective polarizing plate 49 has passed through the λ / 4 plate 270 twice, so the polarization is converted to the polarization (for example, P polarization) that passes through the reflective polarizing plate 49. Therefore, the light whose polarization has been converted passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that regarding the polarization design related to polarization conversion, the polarization may be configured in the reverse direction (reversing S polarization and P polarization) from the above description.

[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 luminance-modulated according to the video signal to display an image on the panel surface. A plurality of LEDs constituting the light source are provided as in the above example (however, only one is shown in FIG. 24 for the longitudinal section), and these are attached to the collimator 18 at predetermined positions.

[0102] Note that each collimator 18 is formed of a light-transmissive resin such as acrylic or glass, for example. And this collimator 18 may have an outer peripheral surface in a conical convex shape obtained by rotating a parabolic cross section. At the top, it may have a concave portion formed with a convex portion (that is, a convex lens surface) at the center. Also, at the center of the flat portion, it has a convex lens surface protruding outward (or a concave lens surface recessed inward may also be acceptable). Note that the parabolic surface forming the conical outer peripheral surface of the collimator 18 is set within a range of angles that can totally reflect the light emitted from the LED in the peripheral direction inside it, or a reflective surface is formed.

[0103] Note that the LEDs are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the collimator 18 such that the LEDs on its surface are respectively positioned at the center of the top of the conical convex shape (the concave portion if there is a concave portion at the top).

[0104] According to such a configuration, among the light emitted from the LED, particularly the light emitted from the central portion thereof is condensed by the convex lens surface forming the outer shape of the collimator 18 to become parallel light. Further, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface of the collimator 18, and similarly, is condensed to become parallel light. In other words, according to the collimator 18 having a convex lens formed at its central portion and a parabolic surface formed at its peripheral portion, almost all of the light generated by the LED can be taken out as parallel light, and the utilization efficiency of the generated light can be improved.

[0105] The above configuration is the same as the configuration of the light source device of the video display device shown in FIGS. 11, 12, 13, etc. Further, the light converted into substantially parallel light by the collimator 18 shown in FIG. 24 is reflected by the reflection type light guide 304. Among the light, the light of a specific polarization wave passes through the reflection type polarizing plate 49 due to the action of the reflection type polarizing plate 49, and the light of the other polarization wave reflected due to the action of the reflection type polarizing plate 49 passes through the light guide 304 again. The light is reflected by the reflector 271 located at a position opposite to the liquid crystal display panel 11 with respect to the reflection type light guide 304. At this time, the light is polarization-converted by passing through the λ / 4 plate 270 which is a retardation plate twice.

[0106] The light reflected by the reflector 271 passes through the light guide 304 again and enters the reflection type polarizing plate 49 provided on the opposite surface. Since the incident light has been polarization-converted, it passes through the reflection type polarizing plate 49 and is incident on the liquid crystal display panel 11 with the polarization directions aligned. As a result, since all the light of the light source can be utilized, the geometric optical utilization efficiency of the light is doubled. Further, since the polarization degree (extinction ratio) of the reflection type polarizing plate is also multiplied by the extinction ratio of the entire system, by using the light source device of this embodiment, the contrast ratio of the entire display device is significantly improved.

[0107] Note that by adjusting the surface roughness of the reflecting surface of the reflective light guide 304 and the surface roughness of the reflector 271, the light reflection and diffusion angles at their respective reflecting surfaces can be adjusted. For each design, the surface roughness of the reflecting surface of the reflective light guide 304 and the surface roughness of the reflector 271 may be adjusted so that the uniformity of the light incident on the liquid crystal display panel 11 becomes more suitable.

[0108] Note that in the example described with reference to FIG. 24, the quarter-wave plate 270, which is a retardation plate, is configured such that the retardation with respect to the polarized light incident perpendicularly to the quarter-wave plate 270 is λ / 4. However, it is not necessarily required to have such a configuration. In the configuration of FIG. 27, the quarter-wave plate 270 may be a retardation plate in which the phase changes by 90° (λ / 2) when the polarized light passes through twice. Also, the thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarized light.

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

[0110] Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) for converting the diffusion characteristics in the vertical and horizontal directions (not shown in the front-back direction of the drawing) of the drawing are used on the light-emitting side of the light from the collimator 18, and the light from the collimator 18 is made to enter between the two optical sheets (diffusion sheets). These optical sheets may be configured as one sheet instead of two sheets. In the case of a single-sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes of the front and back surfaces of the single optical sheet.

[0111] Also, a configuration may be adopted in which a plurality of diffusion sheets are used to distribute the diffusion effect among the respective diffusion sheets. Here, in the example of FIG. 25, regarding the reflection diffusion characteristics due to the front surface shape and the back surface shape of the optical sheet 207A and the optical sheet 207B, it is advisable to optimally design the number of LEDs, the divergence angle from the LED substrate (optical element) 102, and the optical specifications of the collimator 18 as design parameters so that the surface density of the light beam emitted from the liquid crystal display panel 11 becomes uniform. That is, the diffusion characteristics are adjusted by the front surface shape of a plurality of diffusion sheets instead of the light guide.

[0112] In the example shown in FIG. 25, the polarization conversion is performed in the same manner as in Example 3 of the display device described above. That is, in the example of FIG. 25, the reflective polarizing plate 49 may be configured to have the characteristic of reflecting S-polarized light (transmitting P-polarized light). In that case, among the light emitted from the LED which is the light source, the P-polarized light is transmitted, and the transmitted light is incident on the liquid crystal display panel 11. Among the light emitted from the LED which is the light source, the S-polarized light is reflected, and the reflected light passes through the retardation plate 270 shown in FIG. 25.

[0113] Then, the light that has passed through the retardation plate 270 is reflected by the reflector 271. The light reflected by the reflector 271 passes through the retardation plate 270 again and is converted into P-polarized light. The polarization-converted light passes through the reflective polarizing plate 49 and is incident on the liquid crystal display panel 11. Note that the λ / 4 plate 270 which is the retardation plate in FIG. 25 does not necessarily need to have a retardation of λ / 4 with respect to the polarization incident perpendicularly to the λ / 4 plate 270. In the configuration of FIG. 25, the λ / 4 plate 270 may be a retardation plate whose phase changes by 90° (λ / 2) when the polarization passes through twice. The thickness of the retardation plate may be adjusted according to the incident angle distribution of the polarization. Also, in FIG. 25, regarding the polarization design related to the polarization conversion, the polarization may be configured in the reverse (reversing S-polarized light and P-polarized light) from the above description.

[0114] 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 by the plot curves of "Conventional Characteristics (X direction)" in Fig. 32(A) and "Conventional Characteristics (Y direction)" in Fig. 32(B) for general TV applications.

[0115] In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel of this embodiment are such as those shown by the plot curves of "Example 1 (X direction)" in Fig. 32(A) and "Example 1 (Y direction)" in Fig. 32(B).

[0116] In a specific example, when set such that the viewing angle at which the luminance becomes 50% of the luminance in the front view (angle 0 degrees) (the luminance is reduced to about half) is 13 degrees, it becomes about 1 / 5 of the angle of the diffusion characteristics (angle 62 degrees) of a general household TV application device. Similarly, in an example where the viewing angles in the vertical direction are set unevenly between the upper and lower sides, the reflection angle and the area of the reflection surface of the reflective light guide are optimized so that the upper viewing angle is suppressed (narrowed) to about 1 / 3 of the lower viewing angle.

[0117] By setting the viewing angle and the like as described above, compared with a conventional liquid crystal TV, the amount of light of the video heading in the viewing direction of the user increases significantly (greatly improved in terms of the brightness of the video), and the luminance of such a video becomes 50 times or more.

[0118] Furthermore, when the viewing angle characteristics shown in "Example 2" of Fig. 32 are adopted, when set such that the viewing angle at which the luminance becomes 50% of the luminance of the video obtained in the front view (angle 0 degrees) (the luminance is reduced to about half) is 5 degrees, it becomes about 1 / 12 of the angle (narrow viewing angle) of the diffusion characteristics (angle 62 degrees) of a general household TV application device. Similarly, in an example where the viewing angles in the vertical direction are set evenly between the upper and lower sides, the reflection angle and the area of the reflection surface of the reflective light guide are optimized so that such a vertical viewing angle is suppressed (narrowed) to about 1 / 12 of the conventional one.

[0119] By making such settings, the luminance (light quantity) of the video heading towards the viewing direction (the user's line of sight direction) is significantly improved compared to conventional LCD TVs, and the luminance of such video becomes 100 times or more.

[0120] As described above, by taking the viewing angle as the included angle, the amount of light flux heading towards the viewing direction can be concentrated, so the light utilization efficiency is significantly improved. 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 increase in luminance with the same power consumption, and it can be made into a video display device corresponding to an information display system for bright outdoors.

[0121] When using a large liquid crystal display panel, the light around the screen is directed inward so that it heads towards the viewer's direction when the viewer is facing the center of the screen, thereby improving the overall uniformity of the screen brightness. FIG. 15 shows the convergence angles of the long side and the short side of the liquid crystal display panel when the distance L from the liquid crystal display panel to the viewer and the panel size of the video display device (screen ratio 16:10) are used as parameters.

[0122] In the figure shown above FIG. 15, it is premised on the case of viewing a video with the screen of the liquid crystal display panel being vertically long (hereinafter also referred to as "vertically used"). In this case, the convergence angle may be set according to the short side of the liquid crystal display panel (refer to the direction of arrow V in FIG. 15 as appropriate). As a more specific example, as can be seen from the plot graph in FIG. 15, for example, when viewing a 22" panel vertically and the viewing distance is 0.8 m, by setting the convergence angle to 10 degrees, the video light from each corner (4 corners) of the screen can be effectively projected or output towards the viewer.

[0123] Similarly, when viewing a 15" panel vertically and the viewing distance is 0.8 m, if the convergence angle is set to 7 degrees, the video light from the 4 corners of the screen can be effectively directed towards the viewer. As described above, by directing the video light around the screen according to the size of the liquid crystal display panel and whether it is vertically used or horizontally used towards the viewer who is in the optimal position for viewing the center of the screen, the overall uniformity of the screen brightness can be improved.

[0124] As a basic configuration, as shown in FIG. 16 described above, a light beam with a sandwiching angle and directivity characteristics is made incident on the liquid crystal display panel 11 by a light source device, and the luminance is modulated in accordance with a video signal, so that the video information displayed on the screen of the liquid crystal display panel 11 and the spatial floating image reflected by the retroreflective member are displayed outdoors or indoors through the transparent member 100.

[0125] Hereinafter, a plurality of examples of another example of the light source device will be described. Any of these other examples of the light source device may be adopted in place of the light source device of the example of the video display device described above.

[0126] When using a large liquid crystal display panel, as described above, the light around the screen is directed inward so as to face the viewer's direction when the viewer is facing the center of the screen, thereby improving the overall surface brightness of the screen. On the other hand, binocular parallax occurs depending on which of the viewer's left and right eyes is used for viewing. FIG. 16 shows the convergence angle between the long side and the short side of the liquid crystal display panel with the distance (viewing distance) L from the liquid crystal display panel to the viewer and the panel size (screen ratio 16:10) of the video display device as parameters, obtained based on the positions of the left and right eyes.

[0127] The smaller the panel size and the closer the viewing distance, the larger the convergence angle due to 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. Therefore, for example, in a small panel of 7 inches or less, the light diffusion characteristics of the light source shown in FIG. 32 are expanded, or the light is given directivity characteristics, etc., so that the video light is directed to the optimal viewing range of the system.

[0128] Furthermore, in order to obtain horizontal and vertical directivity 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 reflecting surface of the light guide body of the light source device 13 described above.

[0129] <Example 1 of Light Source Device> Next, with reference to FIGS. 26(a) and 26(b), another example of the light source device will be described. FIG. 26(a) is a diagram in which a part of the liquid crystal display panel 11 and the diffusion plate 206 are omitted for explaining the light guide 311.

[0130] FIG. 23 shows a state in which the LEDs 14 constituting the light source are provided on the substrate 102. These LEDs 14 and the substrate 102 are attached to a predetermined position with respect to the reflector 300.

[0131] As shown in FIG. 26(a), the LEDs 14 are arranged in a row in a direction parallel to the side (the short side in this example) of the liquid crystal display panel 11 on the side where the reflector 300 is arranged. In the illustrated example, the reflector 300 is arranged corresponding to such an arrangement of the LEDs. Note that a plurality of reflectors 300 may be arranged.

[0132] In one specific example, each of the reflectors 300 is formed of a plastic material. As another example, the reflector 300 may be formed of a metal material or a glass material, but since the plastic material is easier to mold, the plastic material one is used in this embodiment.

[0133] As shown in FIG. 26(b), the inner surface (the right side in the figure) of the reflector 300 includes a reflecting surface (hereinafter may be referred to as a "parabolic surface") 305 having a shape obtained by cutting a parabolic surface by a meridian plane. The reflector 300 reflects the divergent light emitted from the LED 14 by the above-described reflecting surface 305 (parabolic surface) to convert it into substantially parallel light, and makes the converted light incident on the 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 the reflector 300 has a shape asymmetric with respect to the optical axis of the light emitted from the LED 14. Further, the reflecting surface 305 of the reflector 300 is a parabolic surface as described above, and by arranging the LED at the focus of such a parabolic surface, the light beam after reflection is converted into substantially parallel light.

[0135] Since LED14 is a surface light source, even if it is arranged at the focus of the parabolic surface, the divergent light emitted from the LED cannot be completely converted into parallel light, but this does not affect the performance of the light source of the present invention. LED14 and the reflector 300 form a pair. In order to ensure a predetermined performance with an attachment accuracy of ±40 μm of the LED14 to the substrate 102, the attachment of the LED substrate should be limited to a maximum of 10 or less, and it is advisable to limit it to about 5 considering mass productivity.

[0136] Although LED14 and the reflector 300 are in proximity in part, heat can be dissipated into the space on the opening side of the reflector 300, so the temperature rise of the LED can be reduced. For this reason, a plastic-molded reflector 300 can be used. As a result, the shape accuracy of the reflecting surface can be improved by more than 10 times compared to a reflector made of glass material, so the light utilization efficiency can be improved.

[0137] On the other hand, a reflecting surface is provided on the bottom surface 303 of the light guide 311. The light from LED14 is converted into a parallel light beam by the reflector 300, then reflected by the reflecting surface, and emitted toward the liquid crystal display panel 11 arranged opposite to the light guide 311. As shown in FIG. 26, the reflecting surface provided on the bottom surface 303 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300.

[0138] Also, the shape of the reflecting surface provided on the bottom surface 303 may be a planar shape. At this time, the refracting surface 314 provided on the surface of the light guide 311 facing the liquid crystal display panel 11 refracts the light reflected by the reflecting surface provided on the bottom surface 303 of the light guide 311 to accurately adjust the light quantity and the emission direction of the light beam toward the liquid crystal display panel 11.

[0139] As shown in FIG. 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 plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300. The inclinations of the plurality of surfaces refract the light reflected by the reflecting surface provided on the bottom surface 303 of the light guide 311 toward the liquid crystal display panel 11. Further, the refractive surface 314 may also be a transmissive surface.

[0140] In addition, when there is a diffusion plate 206 in front of the liquid crystal display panel 11, the light reflected by the reflecting surface is refracted toward the diffusion plate 206 due to the plurality of inclinations of the refractive surface 314. That is, the extending directions of the plurality of surfaces with different inclinations of the refractive surface 314 and the extending directions of the plurality of surfaces with different inclinations of the reflecting surface provided on the bottom surface 303 are parallel. By making the extending directions of both parallel, the angle of light can be adjusted more preferably. On the other hand, the LED 14 is soldered to the metallic substrate 102. Therefore, the heat generated by the LED can be dissipated into the air through the substrate.

[0141] Also, the reflector 300 may be in contact with the substrate 102, or a space may be provided therebetween. When a space is provided, the reflector 300 is adhesively disposed on the housing. By providing a space, the heat generated by the LED can be dissipated into the air, improving the cooling effect. As a result, the operating temperature of the LED can be reduced, realizing the maintenance of luminous efficiency and the extension of the service life.

[0142] <Another Example 2 of the Light Source Device> Subsequently, regarding the optical system configuration of a light source device in which the light utilization efficiency is improved by 1.8 times using polarization conversion with respect to the light source device shown in FIG. 26, it will be described in detail with reference to FIGS. 27A(1)(2), FIGS. 27B(1)(2), FIG. 27C, and FIGS. 27D(1)(2). Note that the illustration of the sub-reflector 308 is omitted in FIG. 27A(1).

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

[0144] Among these, the base material 320 shown in FIG. 27A(2) is the base material of the substrate 102. Generally, since the metallic substrate 102 has heat, in order to insulate (heat-insulate) the heat of such a substrate 102, it is preferable to use a plastic material or the like for the base material 320. The material of the reflector 300 and the shape of the reflecting surface may be the same material and shape as those in the example of the light source device in FIG. 26.

[0145] Also, the reflecting surface of the reflector 300 may have a shape asymmetric with respect to the optical axis of the emitted light of the LED 14. The reason for this will be described with reference to FIG. 27A(2). In this embodiment, similar to the example in FIG. 26, the reflecting surface of the reflector 300 is a paraboloid, and the center of the light-emitting surface of the LED, which is a surface light source, is arranged at the focal position of the paraboloid.

[0146] Also, due to the characteristics of the paraboloid, the light emitted from the four corners of the light-emitting surface also becomes a substantially parallel light beam, and only the emission direction is different. Therefore, even if the light-emitting portion has an area, if the distance between the polarization conversion element arranged in the subsequent stage and the reflector 300 is short, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected.

[0147] Also, even if the mounting position of the LED 14 is displaced within 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. Further, even when the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light beam only moves within the ZX plane, and the mounting accuracy of the LED, which is a surface light source, can be significantly reduced. Although the reflector 300 having a reflecting surface obtained by meridionally cutting out a part of the paraboloid has been described in this embodiment, an LED may be arranged on a part obtained by cutting out the entire paraboloid as the reflecting surface.

[0148] On the one hand, in this embodiment, as shown in FIGS. 27B(1) and 27C, the divergent light emitted from the LED 14 is reflected by the parabolic surface 321 and converted into substantially parallel light, and then incident on the end face of the subsequent polarization conversion element 21, and the polarization conversion element 21 aligns it to a specific polarization state. This is a characteristic configuration. With this characteristic configuration, in the present invention, the light utilization efficiency becomes 1.8 times that of the example shown in FIG. 26 described above, and a highly efficient light source can be realized.

[0149] At this time, it should be noted that the substantially parallel light reflected by the parabolic surface 321 from the divergent light emitted from the LED 14 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 to make the light incident on the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11.

[0150] Here, in the example of this figure, the light (main ray) entering the reflector from the LED is arranged so that the direction of the light entering the liquid crystal display panel is substantially parallel. This arrangement is easy to arrange in terms of design, and it is also preferable to arrange the heat source under the light source device because air can escape upward, which can reduce the temperature rise of the LED.

[0151] Also, as shown in FIG. 27B(1), in order to improve the capture rate of the divergent light emitted from the LED 14, the light beam that cannot be captured by the reflector 300 is reflected by the sub-reflector 308 provided on the light shielding plate 309 arranged above the reflector, and then reflected by the inclined surface of the lower sub-reflector 310 and incident on the effective area of the subsequent polarization conversion element 21 to further improve the light utilization efficiency. That is, in this embodiment, a part of the light reflected by the reflector 300 is reflected by the sub-reflector 308, and the light reflected by the sub-reflector 308 is reflected by the sub-reflector 310 in the direction toward the light guide 306.

[0152] The substantially parallel light beam aligned in a specific polarization state by the polarization conversion element 21 is reflected by the reflection shape provided on the surface of the reflective light guide 306 toward the liquid crystal display panel 11 disposed opposite to 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 according to the shape and arrangement of the reflector 300 described above, the reflection surface shape (cross-sectional shape) of the reflective light guide, the inclination of the reflection surface, and the surface roughness.

[0153] As the reflection surface shape provided on the surface of the light guide 306, a plurality of reflection surfaces are arranged opposite to the light emitting surface of the polarization conversion element, and the inclination, area, height, and pitch of the reflection surface are optimized according to the distance from the polarization conversion element 21, so that, as described above, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is set to a desired value.

[0154] As shown in FIG. 27B(2), the reflection surface 307 provided on the reflective light guide is configured to have a plurality of inclinations on one surface, so that the adjustment of the reflected light can be realized with higher precision. In addition, as a configuration in which one surface has a plurality of inclinations on the reflection surface, the region used as the reflection surface may be a plurality of surfaces, or multiple surfaces, or a curved surface. Furthermore, due to the diffusion action of the diffusion plate 206, a more uniform light quantity distribution is realized. The light incident on the diffusion plate closer to the LED realizes a uniform light quantity distribution by changing the inclination of the reflection surface.

[0155] In this embodiment, the base material of the reflection surface 307 uses a plastic material such as heat-resistant polycarbonate. Also, the angle of the reflection surface 307 immediately after the emission of the λ / 2 plate 213 changes according to the distance between the λ / 2 plate and the reflection surface.

[0156] Also in this embodiment, although the LED 14 and the reflector 300 are close to each other in part, heat can be dissipated to the space on the opening side of the reflector 300, and the temperature rise of the LED can be reduced. Further, the substrate 102 and the reflector 300 may be arranged upside down with respect to FIGS. 27A, 27B, and 27C.

[0157] However, when the substrate 102 is placed on top, the substrate 102 gets closer 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 (the side far from the liquid crystal display panel 11) makes the configuration inside the device simpler.

[0158] A light shielding plate 410 may be provided on the light incident surface of the polarization conversion element 21 so that light unnecessary for the subsequent optical system does not enter. With such a configuration, a light source device with suppressed temperature rise can be realized. In the polarizing plate provided on the light incident surface of the liquid crystal display panel 11, the temperature rise is reduced by absorption in the light beam with uniform polarization of the present invention. However, when reflected by the reflection type light guide, the polarization direction rotates and part of the light is absorbed by the incident side polarizing plate. Furthermore, although 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, there is sufficient space between the reflection surface of the reflection type light guide 306 and the liquid crystal display panel 11, enabling natural cooling.

[0159] Figure 27D is a modified example of the light source device of Figures 27B(1) and 27C. Figure 27D(1) shows a partial extraction of the light source device of Figure 27B(1) and illustrates its modified example. Since the other configurations are the same as those of the light source device described above in Figure 27B(1), the illustration and repeated description are omitted.

[0160] First, in the example shown in Figure 27D(1), the height of the concave portion 319 of the sub-reflector 310 is adjusted so that the principal ray of the fluorescence output laterally (in the X-axis direction) from the phosphor 114 (refer to the straight line extending in the direction parallel to the X-axis in Figure 27D(1)) passes out of the concave portion 319 of the sub-reflector 310 and is at a position lower than the phosphor 114. Further, the height of the light shielding plate 410 in the Z-axis direction is adjusted to be lower with respect to the position of the phosphor 114 so that the principal ray of the fluorescence output laterally from the phosphor 114 is not blocked by the light shielding plate 410 and enters the effective region of the polarization conversion element 21.

[0161] In addition, the reflecting surface of the convex portion of the unevenness at the top of the sub-reflector 310 reflects the light reflected by the sub-reflector 308 in order to guide the light reflected by the sub-reflector 308 to the light guide 306. Therefore, the height of the convex portion 318 of the sub-reflector 310 is adjusted so that the light reflected by the sub-reflector 308 is reflected and incident on the effective area of the subsequent polarization conversion element 21, thereby further improving the light utilization efficiency.

[0162] Note that the sub-reflector 310 is arranged to extend in one direction as shown in Fig. 27A(2) and has an uneven shape. Further, at the top of the sub-reflector 310, unevenness having one or more concave portions are arranged periodically along one direction. By adopting such an uneven shape, the principal ray of the fluorescence output laterally from the phosphor 114 can be configured to be incident on the effective area of the polarization conversion element 21.

[0163] Also, the uneven shape of the sub-reflector 310 is periodically arranged at a pitch where the concave portion 319 comes to the position where the LED 14 is located. That is, each of the phosphors 114 is periodically arranged along one direction corresponding to the pitch of the arrangement of the concave portions of the unevenness of the sub-reflector 310. When the phosphor 114 is provided in the LED 14, the phosphor 114 may be expressed as the light emitting portion of the light source.

[0164] Fig. 27D(2) shows an extract of a part of the light source device of Fig. 27C and illustrates a modified example thereof. Since the other configurations are the same as those of the light source device of Fig. 27C, the illustration and repeated description are omitted. As shown in Fig. 27D(2), the sub-reflector 310 may not be provided, but as in Fig. 27D(1), the height of the light shielding plate 410 is adjusted to be lower in the Z-axis direction with respect to the position of the phosphor 114 so that the principal ray of the fluorescence output laterally from the phosphor 114 is not blocked by the light shielding plate 410 and is incident on the effective area of the polarization conversion element 21.

[0165] Regarding the light source devices of FIGS. 27A, 27B, 27C, and 27D, as shown in 27A(1), side walls 400 may be provided to prevent dust from entering the space between the reflecting 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 the light source device from the outside. When the side walls 400 are provided, they are arranged so as to sandwich the space between the light guide 306 and the diffusion plate 206.

[0166] The light emitting surface of the polarization conversion element 21 that emits the light polarization-converted by the polarization conversion element 21 faces the space surrounded by the side wall 400, the light guide 306, the diffusion plate 206, and the polarization conversion element 21. Also, among the inner surfaces of the side wall 400, the surface of the portion that covers the space from which light is output from the emitting surface of the polarization conversion element 21 (the space to the right of the emitting surface of the polarization conversion element 21 in FIG. 27B(1)) from the side uses a reflective surface having a reflective film or the like. That is, the surface of the side wall 400 facing the above space includes a reflective region having a reflective film. By making the surface of the side wall 400 in that portion the reflective surface, the light reflected by the reflective surface can be reused as the light source light, and the luminance of the light source device can be improved.

[0167] Among the inner surfaces of the side wall 400, the surface of the portion that covers the polarization conversion element 21 from the side is a surface with a low light reflectance (such as a black surface without a reflective film). This is because if reflected light is generated on the side surface of the polarization conversion element 21, light in an unexpected polarization state is generated, which causes stray light. In other words, by making the above surface a surface with a low light reflectance, the generation of stray light and light in an unexpected polarization state in the image can be prevented or suppressed. Also, a hole through which air passes may be formed in a part of the side wall 400 so as to improve the cooling effect.

[0168] Note that the light source devices of FIGS. 27A, 27B, 27C, and 27D have been described on the premise of a configuration using the polarization conversion element 21. However, the polarization conversion element 21 may be omitted from these light source devices. In this case, the light source device can be provided at a lower cost.

[0169] <Another Example 3 of the Light Source Device> Next, with reference to FIGS. 28A(1), (2), (3), and 28B, the configuration of the optical system of the light source device using the reflective light guide 304 based on the light source device shown in Example 1 of the light source device will be described in detail.

[0170] FIG. 28A shows a state in which the LEDs 14 constituting the light source are provided on the substrate 102. These are configured as a unit 328 having a plurality of blocks with the collimator 18 and the LED 14 as a pair of blocks. Since the collimator 18 of this embodiment is close to the LED 14, a glass material is adopted in consideration of heat resistance. The shape of the collimator 18 is the same as the shape described for the collimator 15 in FIG. 17. Further, by providing the light shielding plate 317 in the previous stage before the incident light enters the polarization conversion element 21, unnecessary light is prevented or suppressed from entering the subsequent optical system, and the temperature rise due to the unnecessary light is reduced.

[0171] Regarding the other configurations and effects of the light source shown in FIG. 28A, since they are the same as those in FIGS. 27A, 27B, 27C, and 27D, repeated explanations will be omitted. The light source device of FIG. 28A may be provided with side walls in the same manner as described in FIGS. 27A, 27B, and 27C. Since the configuration and effects of the side walls have already been described, repeated explanations will be omitted.

[0172] FIG. 28B is a cross-sectional view of FIG. 28A(2). Regarding the configuration of the light source shown in FIG. 28B, it is common to a part of the structure of the light source in FIG. 18 and has already been described in FIG. 18, so repeated explanations will be omitted.

[0173] <Another Example 4 of the Light Source Device> Next, the light source device of FIG. 29 is configured as a unit 328 having a plurality of blocks with the collimator 18 and the LED 14 used in the light source device shown in FIG. 28 as a pair of blocks. Regarding the configuration of the optical system of the light source device using the LEDs arranged at both ends on the back surface of the liquid crystal display panel 11 and the reflective light guide 504, it will be described in detail with reference to FIGS. 29(a), (b), and (c).

[0174] Figure 29 shows the state where the LED 14 constituting the light source is attached to the substrate 505, and these are configured by a unit 503 having a plurality of blocks in which the collimator 18 and the LED 14 form a pair of blocks. The unit 503 is arranged at both ends of the back surface of the liquid crystal display panel 11 (in this embodiment, three units are arranged side by side in the short side direction). The light output from the unit 503 is reflected by the reflective light guide 504 and is configured to be incident on the oppositely arranged liquid crystal display panel 11 (shown in FIG. 29(c)).

[0175] As shown in FIG. 29(c), the reflective light guide 504 is divided into two blocks corresponding to the units arranged at its respective ends and is arranged such that the central part is the highest. Since the collimator 18 is close to the LED 14, a glass material is adopted in consideration of the heat resistance to the heat emitted from the LED 14. The shape of the collimator 18 is the same as the shape described for the collimator 15 in FIG. 17.

[0176] The light from the LED 14 is incident on the polarization conversion element 501 through the collimator 18. The configuration is such that the distribution of the light incident on the subsequent reflective light guide 504 is adjusted according to the shape of the optical element 81. That is, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is optimally designed by adjusting the shape of the collimator 18 described above, the arrangement and the shape of the optical element 81, the diffusion characteristics and the reflective surface shape (cross-sectional shape) of the reflective light guide, the inclination of the reflective surface, and the surface roughness of the reflective surface.

[0177] As the reflective surface shape provided on the surface of the reflective light guide 504, as shown in FIG. 29(b), a plurality of reflective surfaces are arranged facing the emission surface of the polarization conversion element, and the inclination, area, height, and pitch of the reflective surface are optimized according to the distance from the polarization conversion element 21. Also, by dividing the region that becomes the same reflective surface (that is, the surface facing the polarization conversion element) into polyhedrons, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 can be made a desired value (optimized) as described above.

[0178] The reflecting surface provided on the reflective light guide is configured such that one surface (the region for reflecting light), like the reflective light guide described with reference to FIG. 27B, has a shape with a plurality of inclinations (in the example of FIG. 29, it is divided into 14 parts in the XY plane and consists of different inclined surfaces), enabling more precise adjustment of the reflected light. Further, in order to prevent the reflected light from the reflective light guide from leaking from the side surface of the light source device 13, a light shielding wall 507 is provided to prevent the generation of leakage light in directions other than the desired direction (the direction toward the liquid crystal display panel 11).

[0179] Also, the unit 503 arranged on the left and right of the reflective light guide 504 in FIG. 29 may be replaced with the light source device in FIG. 27. That is, a plurality of the light source devices in FIG. 27 (substrate 102, reflector 300, LED 14, etc.) may be prepared, and such a plurality of light source devices may be arranged at positions facing each other as shown in FIGS. 29(a), (b), and (c).

[0180] FIG. 30 is a cross-sectional view showing an example of the shape of the diffusion plate 206. As described above, the divergent light output from the LED is converted into substantially parallel light by the reflector 300 or the collimator 18, converted into a specific polarization wave by the polarization conversion element 21, and then reflected by the light guide. The light beam reflected by the light guide passes through the flat portion of the incident surface of the diffusion plate 206 and enters the liquid crystal display panel 11 (refer to the two solid line arrows indicating "reflected light from the light guide" in FIG. 30).

[0181] Also, among the light emitted from the polarization conversion element 21, the divergent light beam is totally reflected by the inclined surface of the protrusion having an inclined surface provided on the incident surface of the diffusion plate 206 and enters the liquid crystal display panel 11. In order to totally reflect the light emitted from the polarization conversion element 21 by the inclined surface of the protrusion of the diffusion plate 206, the angle of the inclined surface of the protrusion is changed based on the distance from the polarization conversion element 21. When the angle of the inclined surface of the protrusion on the side far from the polarization conversion element 21 or the side far from the LED is α, and the angle of the inclined surface of the protrusion on the side close to the polarization conversion element 21 or the side close to the LED is α', α is smaller than α' (α < α'). By setting it in this way, it becomes possible to effectively utilize the polarized light-converted light beam.

[0182] <Diffusion characteristic control technology of image display device> As a method for adjusting the diffusion distribution of the image light from the liquid crystal display panel 11, a lenticular lens is provided 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 the shape of the lens is optimized. That is, by optimizing the shape of the lenticular lens, the emission characteristics of the image light (hereinafter also referred to as "image light beam") emitted from the liquid crystal display panel 11 in one direction can be adjusted.

[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 mode may be adjusted. That is, by adjusting the arrangement of the microlens array, the emission characteristics of the image light beam emitted from the image display device 1 in the X-axis and Y-axis directions can be adjusted, and as a result, an image display device having desired diffusion characteristics can be obtained.

[0184] The action of the lenticular lens will 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 windshield 105 to obtain a suitable spatial floating image.

[0185] As a further configuration example, two lenticular lenses may be arranged in combination at the position where the image light emitted from the image display device 1 passes, or a sheet for adjusting the diffusion characteristics by arranging a microlens array in a matrix may be provided. By adopting such an optical system configuration, the luminance (relative luminance) of the image light can be adjusted according to the reflection angle of the image light (the reflection angle with respect to the case of reflection in the vertical direction as the reference (0 degree)) in the X-axis and Y-axis directions.

[0186] In this embodiment, by using such a lenticular lens, excellent optical characteristics that are clearly different from the graph (plot curve) of the conventional characteristics can be obtained as shown in the graphs (plot curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in FIG. 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 sharpened, and further, by changing the balance of the directivity characteristics in the up and down directions (positive and negative directions of the Y-axis), the luminance (relative luminance) of light due to reflection and diffusion can be increased.

[0187] Therefore, according to this embodiment, for video light from a surface-emitting laser video source, which has a narrow diffusion angle (high straight-aheadness) and is video light of only a specific polarization component, when using a video display device according to the prior art, it is possible to suppress the ghost image generated in the retroreflective member and adjust it so that the spatial floating image due to retroreflection can efficiently reach the viewer's eyes.

[0188] Further, with the light source device described above, with respect to the light emission diffusion characteristics (denoted as "conventional characteristics" in the figure) from a general liquid crystal display panel shown in FIGS. 32(a) and (b), it is possible to provide significantly angled directivity characteristics in both the X-axis direction and the Y-axis direction. In this embodiment, by providing such narrow-angle directivity characteristics, it is possible to realize a video display device that emits a video light beam that is nearly parallel in a specific direction and emits light of a specific polarization.

[0189] FIG. 31 shows an example of the characteristics of the lenticular lens adopted in this embodiment. In this example, in particular, the characteristics in the X direction (vertical direction) with respect to the Z axis are shown. For characteristic O, the peak in the light emission direction is at an angle of around 30 degrees upward from the vertical direction (0 degrees), showing a luminance characteristic that is symmetric about the vertical axis. Also, the plot curves of characteristics A and B shown in the graph of FIG. 31 are examples of characteristics in which the image light above the peak luminance is condensed at around 30 degrees to increase the luminance (relative luminance). Therefore, in these characteristics A and B, as can be seen by comparison with the plot curve of characteristic O, in the region where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ > 30°), the luminance (relative luminance) of the light rapidly decreases.

[0190] That is, according to the optical system including the above-described lenticular lens, when the image light beam from the image display device 1 is made incident on the retroreflective member 2, the emission angle and the viewing angle of the image light aligned at the included angle by the light source device 13 can be adjusted, and the degree of freedom in the installation of the retroreflective sheet 2 can be significantly improved. As a result, the degree of freedom in the relationship of the imaging position of the spatial floating image that is reflected or transmitted by the windshield 105 and imaged at a desired position can be significantly improved. As a result, it becomes possible to efficiently reach the eyes of viewers outdoors or indoors as light with a narrow diffusion angle (high straight-ahead property) and only a specific polarization component. According to this, even if the intensity (luminance) of the image light from the image display device 1 is reduced, the viewer can accurately recognize the image light and obtain information. In other words, by reducing the output of the image display device 1, it becomes possible to realize an information display system with low power consumption.

[0191] The various embodiments or examples (i.e., specific examples) to which the present invention is applied have been described in detail above. On the other hand, the present invention is not limited to the above-described embodiments (specific examples), but includes various modifications. For example, the above-described embodiments have described the entire system in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can also be added to the configuration of one embodiment. Further, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0192] The light source device described above is not limited to the spatial floating image display device, and can also be applied to information display devices such as HUDs, tablets, digital signage, and the like.

[0193] In the technology according to this embodiment, by displaying a spatial floating image as high-resolution and high-brightness video information in a spatially floating state, for example, it becomes possible for a user to operate without feeling anxiety about contact infection of infectious diseases. If the technology according to this example is used in a system used by an unspecified number of users, it becomes possible to reduce the risk of contact infection of infectious diseases and provide a contactless user interface that can be used without feeling anxiety. According to the present invention that provides such a technology, it contributes to "3 Ensure healthy lives and promote well-being for all" among the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0194] In addition, in the technology according to the above-described embodiment, by reducing the divergence angle of the emitted video light and further aligning it with a specific polarization, only the regular reflected light is efficiently reflected to the retroreflective member, so that the light utilization efficiency is high and a bright and clear spatial floating image can be obtained. According to the technology of this embodiment, a non-contact user interface with excellent usability that can significantly reduce power consumption can be provided. According to the present invention that provides such a technology, it contributes to "Build the foundation of industry and technological innovation" and "Build sustainable cities" among the Sustainable Development Goals (SDGs) proposed by the United Nations.

[0195] Furthermore, in the technology according to the above-described embodiment, it is possible to form a spatial floating image with video light having high directivity (straightness). In the technology according to this embodiment, even when displaying an image that requires high security in an ATM of a bank or a ticket vending machine at a station, etc., or an image with high confidentiality that needs to be concealed from a person facing the user, by displaying video light with high directivity, it is possible to provide a non-contact user interface with a low risk of the spatial floating image being peeked at by anyone other than the user. By providing the above-described technology, the present invention contributes to "Build sustainable cities" among the Sustainable Development Goals (SDGs) proposed by the United Nations.

Explanation of Reference Numerals

[0196] 1…Image display device, 2,330…Retroreflective member, 3…Spatial image (spatial floating image), 105…Windshield, 100…Transparent plate, 13…Light source device, 54…Light direction conversion panel, 102…LED substrate, 203…Light guide, 205…Reflection sheet, 271…Reflector, 270…λ / 4 plate (phase difference plate), 11…Liquid crystal display panel, 206…Diffusion plate, 21…λ / 4 plate (polarization conversion element), 300…Reflector, 213…λ / 2 plate, 306…Reflective light guide, 307…Reflection surface, 308…Sub-reflector, 331…Spatial floating image, 332…Ghost image, 333…Ghost image, 334…Video light control sheet, 336…Light transmission part, 337…Light absorption part, 340…First distance measuring device, 341…Second distance measuring device, 350…Housing, 360…Optical path folding mirror, 361…Capacitive touch panel, 362…Supporting member, 81…Optical element, 501…Polarization conversion element, 503…Unit, 507…Light shielding wall, 401, 402…Light shielding plate, 320…Base material, Ph…Object

Claims

1. A spatial floating image display system, comprising: a display panel for displaying an image; a light source device for emitting light of a specific polarization; a retroreflective member that reflects the image light from the display panel and displays a real image of a spatial floating image in the air by the reflected light; the light source device includes an optical member for reducing the divergence angle of light from a point-like or planar light source; a reflecting surface that reflects the light from the light source and propagates it to the display panel; part of the divergence angle of the light beam emitted from the light source is adjusted by the shape and surface roughness of the reflecting surface provided on the light source; a depolarizing element is provided on the image light emitting surface of the display panel to optically convert a part of the image light of a specific polarization into the other polarization and pseudo-convert it into natural light; A spatial floating image display system.

2. In the spatial floating image display system according to Claim 1, the light source device includes: a point-like or planar light source; a reflector that reflects the light from the light source; a light guide that guides the light from the reflector toward the display panel; the reflecting surface of the reflector has a shape asymmetric with respect to the optical axis of the light emitted from the light source; the light guide is a reflective light guide that guides light by reflection on a reflecting surface on the surface of the light guide; A spatial floating image display system.

3. In the spatial floating image display system according to Claim 2, a diffusion plate for diffusing the light from the light guide; side walls arranged so as to sandwich the space between the light guide and the diffusion plate; A spatial floating image display system.

4. In the spatial floating image display system according to Claim 2, the reflector is made of a plastic material, a glass material, or a metal material; A spatial floating image display system.

Images