Spatial floating image display device

Abstract

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

Description

Technical Field

[0001] The present invention relates to a spatial floating video information display system and a light source 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 the 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 reducing false detection of operations on the above-described conventional spatial floating video information display system and spatial image, 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 of operations on the displayed spatial image in a spatial floating information display system or a spatial floating video display device.

Means for Solving the Problems

[0006] In order to solve the above problems, for example, the configuration described in the claims is adopted. This application includes a plurality of means for solving the above problems, and an example thereof is given below. A spatial floating image display device includes a display device that displays an image, a light source device that supplies light to the display device, a retroreflective plate that reflects the image light from the display device and displays a real image spatial floating image in the air by the reflected light. The light source device includes a light source, a substrate on which the light source is installed, a reflector that reflects the light from the light source, a light guide that guides the light from the reflector, a diffuser that diffuses the light from the light guide, a second reflector that reflects a part of the light reflected by the reflector, and a third reflector that reflects the light reflected by the second reflector in the direction toward the light guide. The diffuser is arranged close to the display device, and the substrate is arranged at a position farther from the display device than the reflector.

Advantages of the Invention

[0007] According to the present invention, a spatial floating image information display system or a spatial floating image display device having a sensing function with less false detection that can preferably display spatial floating image information 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]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27A

Figure 27B

Figure 27C

Figure 27D

Figure 28A

Figure 28B

Figure 29

Figure 30

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the 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, components having the same or similar functions are denoted by the same reference numerals, and different names may be used as appropriate. In some cases, 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", "spatially floating optical image of a display video", "aerial floating optical image of a 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 partitioning 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 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 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 that occur 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 a light source of the present disclosure can provide a novel and highly usable space-floating video information display system capable of significantly reducing power consumption. According to the technology of the present disclosure, for example, a vehicle floating video information display system capable of displaying a so-called unidirectional space-floating video that can be visually recognized outside the vehicle through a shield glass including a front glass, a rear glass, and a side glass of the vehicle can be provided.

[0014] On the one hand, in the conventional airborne 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 151 as a high-resolution color display video source 150. In the airborne video display device according to the conventional technology, since the video light diffuses at a wide angle, in addition to the reflected light regularly reflected by the retroreflective member 151 (see Fig. 23), as shown in Fig. 24, ghost images (see reference numerals 301 and 302 in Fig. 23) are generated by the video light incident obliquely on the retroreflective member 2a, deteriorating the image quality of the airborne video. Further, in the airborne video display device according to the conventional technology, as shown in Fig. 23, in addition to the normal airborne video 300, a plurality of first ghost images 301, second ghost images 302, etc. are generated. For this reason, the same airborne video that is a ghost image is viewed not only by viewers but also by others, which poses a major problem from the perspective of security.

[0015] <First Configuration Example of Airborne Video Information Display System> Fig. 1(A) is a diagram showing an example of the usage form of the airborne video information display system of the present disclosure. Further, Fig. 1(A) is a diagram for explaining the overall configuration of the airborne 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 "window glass"), which is a translucent member such as glass, 105. According to the airborne 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 of a specific polarization with an angularly directed characteristic 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 window glass 105, and forms a real image, an aerial image 3 (airborne image 3), outside the store. In Fig. 1(A), the inside (inside the store) of the transparent member (here, the window glass) 105 is taken as the depth direction, and the outside of the window glass 105 (for example, the sidewalk) is shown in the foreground.

[0017] On the other hand, means for reflecting a specific polarized wave may be provided on the windshield 105, and the image light beam can be reflected by such means to form a virtual image at a desired position inside the store.

[0018] 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 virtual 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 a video signal.

[0019] Among these, the video signal receiving unit is responsible for, for example, 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). Further, the video signal receiving unit can also function independently as a video receiving and display device. Furthermore, the video signal receiving unit can also display video information from a tablet, a smartphone, etc. Moreover, the video signal receiving unit can also connect a processor (arithmetic processing unit) 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.

[0020] FIG. 2 is a diagram showing an example of the main configuration and the retroreflective unit 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 the video light of a specific polarized wave at an included angle is provided in an oblique direction of a transmissive plate having light transmissivity such as glass (hereinafter referred to as a "transparent member") 100. The video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarized wave having an included angle diffusion characteristic.

[0021] 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.

[0022] Here, since the polarization separation member 101 that selectively reflects the video light of a specific polarization has the property of transmitting the polarization of the other polarization that has been polarization-converted, the video light of the specific polarization after polarization conversion passes through the polarization separation member 101. The video light that has passed through the polarization separation member 101 forms a spatial floating video 3, which is a real image, outside the transparent member 100.

[0023] Note that the light forming the spatial floating video 3 is a set of light rays that converge from the retroreflective member 2 to the optical image of the spatial floating video 3, and these light rays continue to travel straight even after passing through the optical image of the spatial floating video 3. Therefore, unlike the diffused video light formed on a screen by a general projector or the like, the spatial floating video 3 is a video with high directivity.

[0024] Therefore, in the configuration of FIG. 2, when the user views from the direction of arrow A, the spatial floating video 3 is viewed as a bright video, but when another person views from the direction of arrow B, the spatial floating video 3 cannot be viewed as a video at all. This characteristic is very suitable for use in a system that displays videos requiring high security or videos with high confidentiality that need to be concealed from people facing the user.

[0025] Depending on the performance of the retroreflective member 2, the polarization axes of the video light after reflection may become uneven. In this case, some of the video light with uneven polarization axes is reflected by the polarization separation member 101 described above and returns to the video display device 1. This part of the video light is retroreflected on the video display surface of the liquid crystal display panel 11 that constitutes the video display device 1, and may cause a reduction in the image quality of the floating image in space by generating a ghost image.

[0026] Therefore, in this embodiment, an absorption type polarizing plate 12 is provided on the video display surface of the video display device 1. The absorption type polarizing plate 12 can suppress retroreflection by transmitting the video light emitted from the video 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 this 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.

[0027] 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.

[0028] Next, as a typical retroreflective member 2 in FIG. 2(B), the surface shape of the retroreflective member manufactured by Nippon Carbide Kogyo 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 bottom surfaces of the hexagonal prisms and emitted as retroreflected light in the direction corresponding to the incident light, and a spatial floating image, which is a real image, is displayed based on the image displayed on the video display device 1. The resolution of this spatial floating image depends greatly on the outer diameter 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, if the diameter D of the retroreflective portion is 240 μm and the pitch is 300 μm, for example, 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 the resolution 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 integer multiple of one pixel. Also, it is good to arrange the shape so that any side of the retroreflective portion does not overlap with any side of one pixel of the liquid crystal display panel.

[0029] 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 shaping shape 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 with ultraviolet rays to cure it, and the retroreflective member 2 of the desired shape is obtained.

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

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

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

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

[0034] <The third configuration example of the spatial floating video information display system> FIG. 3(B) is a diagram showing another example of the spatial floating video information display system. Similar to FIG. 3(A), the video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having a diffusion characteristic with a sandwiching angle. The liquid crystal display panel 11 can be configured as a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. For example, a polarization separation member 101 that selectively reflects video light of a specific polarization such as a reflective polarizing plate reflects the video light from the liquid crystal display panel 11 toward the retroreflective member (retroreflective portion or retroreflective plate) 2. The difference from the example of FIG. 2 is that the obtained spatial floating video is enlarged as a virtual image X by the concave mirror 5. The configurations of the video display device 1 and the retroreflective member 2 are the same as those in the embodiments shown in FIGS. 2 and 3(A), and the description thereof is omitted. In the configuration of FIG. 3(B), the polarization separation member 101 may further have a convex shape.

[0035] Here, as described with reference to FIG. 2, since the airborne floating video 3 is formed by a highly directional light beam, when viewed from the direction of arrow A, the airborne floating video 3 is viewed as a bright video, but when viewed from the direction of arrow B, the airborne floating video 3 is not viewed as a video at all. Therefore, in the configuration of FIG. 3(B), when the user views from the direction of arrow B, the airborne floating video 3 is located behind the virtual image X, but the user does not view the airborne floating video 3 at all, and only the virtual image X is preferably viewed. Therefore, by taking advantage of this characteristic and configuring as shown in FIG. 3(B) so that the airborne floating video 3 is located behind the virtual image X, it is more suitable because the entire system can be miniaturized than configuring to exclude the airborne floating video 3 from the viewing range of the user X when viewing the virtual image X.

[0036] <Fourth Configuration Example of Spatial Floating Video Information Display System> FIG. 4 is a diagram showing another example of the main configuration of a spatial floating video information display system according to an embodiment of the present invention. Similar to FIG. 3(A) and the like, the video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having a diffusion characteristic with a sandwiching angle. For example, the liquid crystal display panel 11 is composed of a small one with a screen size of about 5 inches to a large liquid crystal display panel exceeding 80 inches. The folding mirror 22 has a transparent member 100 as a substrate. On the surface of the transparent member 100 on the side of the video display device 1, a polarization separation member 101 that selectively reflects video light of a specific polarization, such as a reflective polarizing plate, is provided, and the video light from the liquid crystal display panel 11 is reflected toward the retroreflective portion 2. Thereby, the folding mirror 22 has a function as a mirror. The video light of a specific polarization from the video display device 1 is reflected by a polarization separation member 101 provided on the lower surface of the transparent member 100 (in the illustrated example, a sheet-like polarization separation member 101 is attached to the transparent member 100 using an adhesive.), and enters the retroreflective member 2. Instead of the polarization separation member 101, an optical film having polarization separation characteristics may be vapor-deposited on the surface of the transparent member 100.

[0037] A λ / 4 plate 21 is provided on the light incident surface of the retroreflective member 2, and the video light is passed through twice to perform polarization conversion to convert a specific polarization into the other polarization having a phase difference of 90°. Thereby, the polarization separation member 101 is made to transmit the video light after retroreflection, and a spatial floating video 3 that is a real image is displayed outside the transparent member 100. Here, in the above-described polarization separation member 101, the polarization axis becomes uneven due to retroreflection, so a part of the video light is reflected and returns to the video display device 1. This light is reflected again on the video display surface of the liquid crystal display panel 11 constituting the video display device 1, generating a ghost image and significantly degrading the image quality of the spatial floating image.

[0038] Therefore, in this embodiment, an absorption type polarizing plate 12 is provided on the video display surface of the video display device 1. This absorption type polarizing plate 12 transmits the video light emitted from the video display device 1 and absorbs the reflected light from the above-described polarization separation member 101. By adopting such a configuration, deterioration of the image quality due to the ghost image of the floating image in space can be prevented. Further, in order to reduce deterioration of the image quality due to sunlight or illumination light outside the set, it is preferable to provide an absorption type polarizing plate 102 on the surface of the transparent member 105 on the video light output side.

[0039] Next, as shown in FIG. 5, a plurality of sensors 44 having a TOF (Time of Fly) function are arranged in multiple layers so as to sense the relationship between the distance and position of the object and the sensor 44 with respect to the floating video obtained by the above-described floating video information system. In addition to the coordinates of the object in the plane direction, the coordinates in the depth direction and the moving direction and moving speed of the object can also be sensed.

[0040] In order to read the two-dimensional distance and position, a combination of a non-visible light emitting part and a light receiving part such as infrared rays or ultraviolet rays is linearly arranged in a plurality, the light from the light emitting point is irradiated onto the object, and the reflected light is received by the light receiving part. The distance to the object is clarified by the product of the difference between the time of emission and the time of reception and the speed of light. Further, the coordinates on the plane can be read from the coordinates at the portion where the difference between the emission time and the reception time is the smallest by a plurality of light emitting parts and light receiving parts. As described above, three-dimensional coordinate information can also be obtained by combining the coordinates of the object in the plane (two-dimensional) with a plurality of the above-described sensors.

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

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

[0043] In addition, in the characteristic graphs of FIGS. 8 to 11 (each shown in color), the values of the angles (deg) shown outside the right column are shown from top to bottom in the order of the highest values of the vertical axis, that is, the transmittance (%). For example, in FIG. 8, in the range where the horizontal axis indicates light with a wavelength of approximately 400 nm to 800 nm, the transmittance is the highest when the angle in the vertical (V) direction is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees, 20 degrees, 30 degrees, and 40 degrees. Also, in FIG. 9, in the range where the horizontal axis indicates light with a wavelength of approximately 400 nm to 800 nm, the transmittance is the highest when the angle in the vertical (V) direction is 0 degrees (deg), and the transmittance decreases in the order of 10 degrees, 20 degrees, 30 degrees, and 40 degrees.

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

[0045] As shown in FIGS. 8 and 9, for the reflective polarizing plate with a grid structure, the characteristics regarding light from the direction perpendicular to the polarization axis deteriorate. For this reason, specifications along the polarization axis are desirable, and the light source of this embodiment that can emit the outgoing video light from the liquid crystal display panel 11 at an included angle becomes an ideal light source. Also, regarding the characteristics in the horizontal direction, there is a deterioration in characteristics for light from an oblique direction. Considering the above characteristics, hereinafter, a configuration example of this embodiment will be described in which a light source that can emit the outgoing video light from the liquid crystal display panel 11 at a larger included angle is used as the backlight of the liquid crystal display panel 11. Thereby, a high-contrast spatial floating image can be provided.

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

[0047] This liquid crystal display panel (video display element 11), as indicated by arrow 30 in FIG. 12, obtains an illumination light beam having diffusing characteristics at an included angle by the light from the light source device 13 which is a backlight device, that is, a light beam with strong directivity (linear propagation) and characteristics similar to laser light with the polarization planes aligned in one direction, and modulates the video light according to the input video signal, reflects it by the retroreflective member 2, transmits it through the windshield 105, and forms a spatial floating image which is a real image (see also FIG. 1).

[0048] Also, in FIG. 12, the liquid crystal display panel 11 that constitutes the video display device 1, further includes a light direction conversion panel 54 that adjusts the directivity characteristics of the emitted light beam from the light source device 13, and an included angle diffusion plate (not shown) as required. That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and video light of a specific polarization modulates the light intensity according to the video signal and is emitted (refer to arrow 30 in FIG. 12). Thus, a desired video is projected as light of a specific polarization with high directivity (straightness) through the light direction conversion panel 54 toward the retroreflective member 2, and after being reflected by the retroreflective member 2, it passes through toward the eyes of viewers outside the store (space) to form a spatial floating image 3. Note that a protective cover 50 (refer to FIGS. 13 and 14) may be provided on the surface of the above-described light direction conversion panel 54.

[0049] In this embodiment, in order to improve the utilization efficiency of the emitted light beam 30 from the light source device 13 and significantly reduce power consumption, in the video display device 1 configured to include the light source device 13 and the liquid crystal display panel 11, the light from the light source device 13 (refer to arrow 30 in FIG. 12) is projected toward the retroreflective member 2, and after being reflected by the retroreflective member 2, the directivity can be adjusted by a transparent sheet (not shown) provided on the surface of the windshield 105 so that a floating video is formed at a desired position.

[0050] Specifically, this transparent sheet adjusts the imaging position of the floating video while imparting high directivity by optical components such as a Fresnel lens or a linear Fresnel lens. According to this, the video light from the video display device 1 can efficiently reach an observer outside the windshield 105 (e.g., on the sidewalk) with high directivity (straightness) like laser light. As a result, it is possible to display a high-quality floating video with high resolution and significantly reduce the power consumption of the video display device 1 including the LED element 201 of the light source device 13.

[0051] <Example 1 of Video Display Device> FIG. 13 shows an example of the specific configuration of the video display device 1. In FIG. 13, a liquid crystal display panel 11 and a light direction conversion panel 54 are arranged on the light source device 13 of FIG. 12. This light source device 13 is formed of, for example, plastic or the like on the case shown in FIG. 12, and an LED element 201 and a light guide 203 are housed therein. On the end face of the light guide 203, as also shown in FIG. 12 and the like, in order to convert the divergent light from each LED element 201 into a substantially parallel light beam, it has a shape in which the cross-sectional area gradually increases toward the light receiving part, and has a lens shape that has an effect of gradually reducing the divergence angle by total internal reflection multiple times when propagating inside.

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

[0053] Also, on the frame (not shown) of the liquid crystal display panel 11 attached to the upper surface of the case of the light source device 13, the liquid crystal display panel 11 attached to the frame, and further, an FPC (Flexible Printed Circuits) (not shown) electrically connected to the liquid crystal display panel 11 and the like are attached and configured. That is, the liquid crystal display panel 11 which is a video display element, together with the LED element 201 which is a solid light source, generates a display video by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes an electronic device. At this time, since the generated video light has a narrow diffusion angle and only a specific polarization component, a novel video display device different from the conventional one, which is close to a surface-emitting laser video source driven by a video signal, can be obtained.

[0054] At present, it is technically and safety - wise impossible to obtain a laser beam with the same size as the image obtained by the above - described video display device 1 using a laser device. Therefore, in this embodiment, for example, light similar to the surface - emitting laser video light described above is obtained from the light beam emitted from a general light source equipped with LED elements.

[0055] Subsequently, the configuration of the optical system housed in the case of the light source device 13 will be described in detail with reference to FIG. 14 together with FIG. 13.

[0056] Since FIGS. 13 and 14 are cross - sectional views, only one of the plurality of LED elements 201 constituting the light source is shown, and these are converted into substantially collimated light by the shape of the light - receiving end face 203a of the light guide 203. Therefore, the light - receiving part of the light - guide end face and the LED elements are attached while maintaining a predetermined positional relationship.

[0057] Each of these light guides 203 is formed of a light - transmissive resin such as acrylic, for example. And the LED light - receiving surface at the end of this light guide 203 has, for example, an outer peripheral surface of a conical convex shape obtained by rotating a parabolic cross - section. At its top, it has a concave part with a convex part (i.e., a convex lens surface) formed at its central part, and at the central part of its flat part, it has a convex lens surface protruding outward (or it may be a concave lens surface recessed inward) (not shown). Note that the outer - shape of the light - receiving part of the light guide to which the LED element 201 is attached has a parabolic shape forming a conical outer - peripheral surface, and is set within an angle range that enables total internal reflection of the light emitted from the LED element in the peripheral direction inside it, or a reflecting surface is formed.

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

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

[0060] As described above, the light source device 13 is configured by attaching a light source unit in which a plurality of LED elements 201 as light sources are arranged on a light-receiving end face 203a which is a light-receiving portion provided on the end face of the light guide 203. The divergent light beam from the LED element 201 is made into substantially parallel light by the lens shape of the light-receiving end face 203a of the light guide end face, and as shown by the arrow, it is guided inside the light guide 203 (in a direction parallel to the drawing surface), and by the light beam direction conversion means 204, it is emitted toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front from the drawing surface). By optimizing the distribution (density) of this light beam direction conversion means 204 according to the shape inside or on the surface of the light guide, the uniformity of the light beam incident on the liquid crystal display panel 11 can be adjusted.

[0061] As shown in FIG. 13 or FIG. 14, the above-described light beam direction conversion means 204 emits the light beam propagated inside the light guide 203 toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front from the drawing surface) by providing, for example, portions with different refractive indexes on the shape of the light guide surface or inside the light guide. At this time, if the relative luminance ratio when comparing the luminance of the center of the screen and the peripheral portion of the screen in a state where the liquid crystal display panel 11 is directly facing the center of the screen and the viewpoint is placed at the same position as the diagonal dimension of the screen is 20% or more, there is no practical problem, and if it exceeds 30%, it has even better characteristics.

[0062] Note that, FIG. 13 is a cross-sectional layout view for explaining the configuration and operation of the light source of the present embodiment that performs polarization conversion in the light source device 13 including the above-described light guide 203 and the LED element 201. In FIG. 13, the light source device 13 includes, for example, a light guide 203 provided with a light flux direction conversion means 204 on its surface or inside formed of plastic or the like, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 206, a lenticular lens, etc. On its upper surface, a liquid crystal display panel 11 provided with polarizing plates on the light source light incident surface and the video light exit surface is attached.

[0063] Also, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and selectively reflects one-sided polarized wave (for example, P wave) 212 of the natural light flux 210 emitted from the LED element 201, and reflects it with the reflection sheet 205 provided on one surface (the lower side in the figure) of the light guide 203, and then makes it go toward the liquid crystal display panel 11 again. Therefore, a retardation plate (λ / 4 plate) is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the reflected light flux is converted from P polarization to S polarization by reflecting it with the reflection sheet 205 and passing it twice, thereby improving the utilization efficiency of the light source light as video light.

[0064] The video light flux whose light intensity is modulated by the video signal in the liquid crystal display panel 11 (arrow 213 in FIG. 13) enters the retroreflective member 2, and as shown in FIG. 1, after reflection, it passes through the windshield 105 to obtain a spatial floating image that is a real image inside or outside the store (space).

[0065] FIG. 14 is a cross-sectional layout view for explaining the configuration and operation of the light source of this embodiment that performs polarization conversion in the light source device 13 including the light guide 203 and the LED element 201, similar to FIG. 13. Similarly, the light source device 13 is also composed of, for example, a light guide 203 provided with a light beam direction conversion means 204 on its surface or inside formed of plastic or the like, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 206, a lenticular lens, and the like. On the light guide 203, a liquid crystal display panel 11 having polarizing plates on the light source light incident surface and the video light emitting surface is attached as a video display element.

[0066] Also, on the light source light incident surface (the lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, a film or sheet-like reflective polarizing plate 49 is provided to selectively reflect one-sided polarization (for example, S wave) 211 of the natural light beam 210 emitted from the LED light source 201, reflect it with the reflection sheet 205 provided on one surface (the lower side in the figure) of the light guide 203, and then direct it back toward the liquid crystal display panel 11. A retardation plate (λ / 4 plate) is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the light is reflected by the reflection sheet 205 and passed through twice to convert the reflected light beam from S polarization to P polarization, thereby improving the utilization efficiency of the light source light as video light. The video light beam intensity-modulated by the video signal in the liquid crystal display panel 11 (arrow 214 in FIG. 14) enters the retroreflective member 2 and, as shown in FIG. 1, after reflection, passes through the windshield 105 to obtain a spatial floating image that is a real image inside or outside the store (space).

[0067] In the light source devices shown in FIGS. 13 and 14, in addition to the action of the polarizing plate provided on the light incident surface of the corresponding liquid crystal display panel 11, since the reflective polarizing plate 49 reflects one-sided polarization components, the theoretically obtained contrast ratio is the reciprocal of the cross transmittance of the reflective polarizing plate multiplied by the reciprocal of the cross transmittance obtained by the two polarizing plates attached to the liquid crystal display panel. As a result, high contrast performance can be obtained. In fact, it was experimentally confirmed that the contrast performance of the displayed image was improved by more than 10 times. As a result, a high-quality video comparable to that of self-emitting organic EL was obtained.

[0068] <Example 2 of the video display device> FIG. 15 shows another example of the specific configuration of the video display device 1. The light source device 13 in FIG. 15 is the same as the light source device in FIGS. 17 and the like. This light source device 13 is configured by housing an LED, a collimator, a composite diffusion block, a light guide, etc. in a case made of, for example, plastic, and a liquid crystal display panel 11 is attached to the upper surface thereof. Further, 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 the control circuit thereof is mounted are attached, and on the outer surface of the LED substrate, a heat sink 103, which is a member for cooling the heat generated by the LED elements and the control circuit, is attached (see also FIGS. 17 and 18).

[0069] 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) 403 (see FIG. 7) electrically connected to the liquid crystal display panel 11 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 transmitted light based on a control signal from a control circuit (not shown here) that constitutes the electronic device, thereby generating a display video.

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

[0071] Figures 17 and 18 show LEDs 14a and 14b that constitute a light source, and these are attached to a predetermined position with respect to the collimator 15. Note that each of these collimators 15 is formed of a translucent resin such as acrylic. And as shown in Fig. 18(b), this collimator 15 has a conical convex outer peripheral surface 156 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 in which a convex portion (i.e., a convex lens surface) 157 is formed.

[0072] 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 enables total internal reflection of the light emitted from the LEDs 14a and 14b in the peripheral direction inside it, or a reflecting surface is formed.

[0073] 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.

[0074] According to such a configuration, among the light emitted from the LED 14a or 14b, particularly the light radiated upward (right direction in the figure) from its central portion is condensed by the two convex lens surfaces 157 and 154 that form the outer shape of the collimator 15 and becomes parallel light. Also, the light emitted in the peripheral direction from other portions is reflected by the parabolic surface that forms the conical outer peripheral surface of the collimator 15 and is similarly condensed to become parallel light. In other words, according to the collimator 15 that constitutes a convex lens at its central portion and forms a parabolic surface at 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.

[0075] 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. 18, this polarization conversion element 21 is formed by combining a columnar light-transmissive member having a parallelogram cross section (hereinafter referred to as a parallelogram column) and a columnar light-transmissive member having a triangular cross section (hereinafter referred to as a triangular column), and is configured by arranging a plurality of them in an array parallel to a 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 adjacent light-transmissive members arranged in this array. Further, a λ / 2 phase plate 213 is provided on the emission surface from which the light that has entered the polarization conversion element 21 and passed through the PBS film 211 is emitted.

[0076] A rectangular composite diffusion block 16 shown also in FIG. 18(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 and enters the composite diffusion block 16, and after being diffused by the texture 161 on the emission side, reaches the light guide 17.

[0077] The light guide 17 is a member formed in a rod shape having a substantially triangular cross section (see FIG. 18(b)) by a light-transmissive resin such as acrylic, and as is clear from FIG. 17, a light guide light incident portion (surface) 171 facing the emission surface of the composite diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (surface) 172 forming an inclined surface, and a light guide light emission portion (surface) 173 facing the liquid crystal display panel 11, which is a liquid crystal display element, via the second diffusion plate 18b.

[0078] In the light guide light reflecting portion (surface) 172 of this light guide 17, as also shown in Fig. 17 which is a partial enlarged view thereof, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. And 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 from 1 to 130) with the horizontal plane indicated by the dashed line in the figure. As an example, here, αn is set to be 43 degrees or less (however, 0 degrees or more).

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

[0080] According to the light source device 13 configured as described above, the parallel light emitted from the emission surface of the synthetic diffusion block 16 is diffused through the first diffusion plate 18a and enters the light guide incident portion (surface) 171 of the light guide 17. The light incident on the light guide 17, as is clear from Fig. 17, reaches the light guide light reflecting portion (surface) 172 while being slightly bent (deflected) upward when entering the light guide incident portion (surface) 171, and is reflected by the reflecting surface (172a) of the light guide light reflecting portion (surface) 172 and reaches the liquid crystal display panel 11 provided on the upper emission surface in Fig. 17.

[0081] 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 S-polarized light wave light source device. 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 also be obtained by providing it in the optical path leading to the liquid crystal display panel 11.

[0082] Note that, in the light guide light reflection part (surface) 172, a large number of reflection surfaces 172a and connection surfaces 172b are alternately formed in a sawtooth shape. The illumination light beam is totally reflected on each reflection surface 172a and goes upward. Further, a sandwiching angle diffuser plate is provided on the light guide light emission part (surface) 173 and 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 emission surface 173 and the liquid crystal display panel 11, but the same effect can be obtained even if it is provided on the emission surface of the liquid crystal display panel 11.

[0083] <Example 2 of the light source device of Example 2 of the video display device> Another example of the configuration of the optical system such as the light source device 13 is shown in FIG. 19. Similar to the example shown in FIG. 18, the optical system shown in FIG. 19 also shows a plurality (two in this example) of 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, similar to the example shown in FIG. 18, this collimator 15 has an outer peripheral surface 156 having a conical convex shape obtained by rotating a parabolic cross section, and at the top, it has a concave portion 153 formed with a convex portion (that is, a convex lens surface) 157 at the center thereof. Also, at the center of the flat portion, it has a convex lens surface (or a concave lens surface recessed inward may also be used) 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 LED 14a in the peripheral direction inside it, or a reflecting surface is formed.

[0084] 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 center of the concave portion 153.

[0085] According to such a configuration, among the light emitted from the LED 14a or 14b, in particular, the light radiated 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 the central portion thereof and a parabolic surface formed in the peripheral portion thereof, almost all of the light generated by the LED 14a or 14b can be taken out as parallel light, and the utilization efficiency of the generated light can be improved.

[0086] Note that a light guide 170 is provided on the light emission side of the collimator 15 via a first diffusion plate 18a. The light guide 170 is a member formed in a rod shape with a substantially triangular cross section (see Fig. 19(a)) by a light-transmissive resin such as acrylic, and as is clear from Fig. 19(a), an incident portion (surface) 171 of the light guide light 170 facing the emission surface of the diffusion block 16 via the first diffusion plate 18a, a light guide light reflection portion (surface) 172 forming an inclined surface, and a light guide light emission portion (surface) 173 facing the liquid crystal display panel 11 which is a liquid crystal display element via the reflective polarizing plate 200.

[0087] If a material having a characteristic of reflecting P-polarized light (transmitting S-polarized light) is selected for this reflective polarizing plate 200, for example, P-polarized light among the natural light emitted from the LED which is a light source is reflected, passes through the λ / 4 plate 202 provided on the light guide light reflection portion 172 shown in Fig. 19(b), is reflected by the reflection surface 201, and is converted into S-polarized light by passing through the λ / 4 plate 202 again, so that all the light beams incident on the liquid crystal display panel 11 are unified into S-polarized light.

[0088] Similarly, if an object with the property of reflecting S-polarized light (transmitting P-polarized light) is selected as the reflective polarizing plate 200, the S-polarized light among the natural light emitted from the LED serving as the light source is reflected, passes through the λ / 4 plate 202 provided on the light reflecting portion 172 of the light guide shown in FIG. 19(b), is reflected by the reflecting surface 201, and is converted into P-polarized light by passing through the λ / 4 plate 202 again. All the light beams incident on the liquid crystal display panel 52 are unified into P-polarized light. Polarization conversion can also be achieved with the configuration described above.

[0089] <Example 3 of the video display device> Subsequently, another example (Example 3 of the video display device) of the specific configuration of the video display device 1 will be described with reference to FIG. 16. The light source device of this video display device 1 converts the divergent 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 is incident on the reflective polarizing plate 49 disposed between the liquid crystal display panel 11 and the reflective light guide 304.

[0090] In the reflective polarizing plate 49, a specific polarization wave (for example, P-polarized light) passes through and is incident on the liquid crystal display panel 11. The other polarization wave (for example, S-polarized light) is reflected by the reflective polarizing plate and heads back toward the reflective light guide 304. 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. The principal ray of the light reflected by the reflective polarizing plate 49 is incident on the transmissive surface of the reflective light guide 304.

[0091] 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 is incident on the reflective polarizing plate 49 again.

[0092] At this time, since the light that re-enters the reflective polarizing plate 49 has passed through the λ / 4 plate 270 twice, the polarization is converted into a 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.

[0093] 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, is luminance-modulated according to the video signal, and a video is displayed on the panel surface. A plurality of LEDs constituting the light source are provided as in the above example (however, only one LED is shown in FIG. 16 due to the longitudinal section), and these are attached to the collimator 18 at predetermined positions.

[0094] Note that each of the collimators 18 is formed of a light-transmitting resin such as acrylic or glass. And this collimator 18 may have an outer peripheral surface having a conical convex shape obtained by rotating a parabolic cross-section. At its top, it may have a concave portion formed with a convex portion (that is, a convex lens surface) at its central portion. Also, at the central portion of its flat portion, it has a convex lens surface protruding outward (or 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 an angle that enables total reflection of the light emitted from the LED in the peripheral direction inside it, or a reflective surface is formed.

[0095] Note that the LEDs are respectively arranged at predetermined positions on the surface of the LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the collimator 18 such that the LEDs on its surface are respectively located at the central portion of the top of the conical convex shape (if there is a concave portion at the top, then at that concave portion).

[0096] 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 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 18, and similarly, is condensed and becomes parallel light. In other words, according to the collimator 18 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 can be taken out as parallel light, and the utilization efficiency of the generated light can be improved.

[0097] The above configuration is the same as the configuration of the light source device of the video display device shown in FIGS. 17, 18, etc. Further, the light converted into substantially parallel light by the collimator 18 shown in FIG. 16 is reflected by the reflection type light guide 304. Among the light, the light of a specific polarization state 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 state reflected by the action of the reflection type polarizing plate 49 passes through the light guide 304 again. The light is reflected by a reflection plate 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.

[0098] The light reflected by the reflection plate 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.

[0099] 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. The surface roughness of the reflecting surface of the reflective light guide 304 and the surface roughness of the reflector 271 may be adjusted for each design so that the uniformity of the light incident on the liquid crystal display panel 11 becomes more suitable.

[0100] Note that in the example described with reference to FIG. 16, 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. 16, 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.

[0101] <Example 4 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. 25. FIG. 25 shows a configuration example in the case where a diffusion sheet is used instead of the reflective light guide 304 in the light source device of Example 3 of the video display device.

[0102] Specifically, two optical sheets (optical sheet 207A and optical sheet 207B) for converting the diffusion characteristics in the vertical direction and the horizontal direction (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.

[0103] Also, a configuration in which a plurality of diffusion sheets are used to distribute the diffusion effect to each diffusion sheet may be adopted. Here, in the example of FIG. 25, regarding the reflection and diffusion characteristics due to the front and back surface shapes of the optical sheet 207A and the optical sheet 207B, it is advisable to optimize the design with 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, instead of the light guide, the diffusion characteristics are adjusted by the front surface shapes of a plurality of diffusion sheets.

[0104] 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 serving as 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 serving as the light source, the S-polarized light is reflected, and the reflected light passes through the retardation plate 270 shown in FIG. 25.

[0105] Then, the light that has passed through the retardation plate 270 is reflected by the reflector 271. The light 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 conversion 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 manner (the configuration in which S-polarized light and P-polarized light are reversed) from the above description.

[0106] The light emitted from the liquid crystal display panel 11 has similar diffusion characteristics in the horizontal direction of the screen (the display direction corresponding to the X-axis of the graph in Fig. 22(A)) and the vertical direction of the screen (the display direction corresponding to the Y-axis of the graph in Fig. 22(B)), as shown by the plot curves of "Conventional Characteristics (X direction)" in Fig. 22(A) and "Conventional Characteristics (Y direction)" in Fig. 22(B) for general TV applications.

[0107] 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. 22(A) and "Example 1 (Y direction)" in Fig. 22(B).

[0108] 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 decreases to about half) is 13 degrees, it becomes about 1 / 5 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 unevenly set 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.

[0109] 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 towards the viewing direction of the user increases significantly (greatly improves in terms of the brightness of the video), and the luminance of such video becomes 50 times or more.

[0110] Furthermore, when the viewing angle characteristics shown in "Example 2" of Fig. 22 are used, 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 decreases to about half) is 5 degrees, it becomes about 1 / 12 of the diffusion characteristics (angle 62 degrees) of a general household TV application device (a narrow viewing angle). Similarly, in an example where the viewing angles in the vertical direction are evenly set 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 vertical viewing angle is suppressed (narrowed) to about 1 / 12 of the conventional one.

[0111] By making such settings, compared with conventional LCD TVs, the luminance (light quantity) of the video heading in the viewing direction (the user's line-of-sight direction) is significantly improved, and the luminance of such video becomes 100 times or more.

[0112] As described above, by taking the viewing angle as the included angle, the light flux amount heading in 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 improvement in luminance with the same power consumption, and it can be made into a video display device corresponding to an information display system for a bright outdoor environment.

[0113] When using a large liquid crystal display panel, the light around the screen is directed inward so that it heads in the viewer's direction when the viewer is facing the center of the screen, thereby improving the overall uniformity of the screen brightness. FIG. 20 shows the convergence angles between 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.

[0114] In the figure shown at the upper side in FIG. 20, 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 in accordance with the short side of the liquid crystal display panel (refer to the direction of arrow V in FIG. 20 as appropriate). As a more specific example, as can be seen from the plot graph in FIG. 20, 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 toward the viewer.

[0115] 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 toward the viewer. As described above, by directing the video light around the screen to the viewer who is in the optimal position for viewing the center of the screen according to the size of the liquid crystal display panel and whether it is vertically used or horizontally used, the overall uniformity of the screen brightness can be improved.

[0116] As a basic configuration, as shown in FIG. 16 and the like described above, a light beam with a sandwiching angle directivity characteristic is made incident on the liquid crystal display panel 11 by a light source device, and is luminance-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.

[0117] 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 above-described example of the video display device.

[0118] <Another Example 1 of the Light Source Device> Referring 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.

[0119] FIG. 26 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 the reflector 300 at a predetermined position.

[0120] 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.

[0121] 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 is used in this embodiment.

[0122] As shown in FIG. 26(b), the inner surface (the right side in the figure) of the reflector 300 is provided with a reflecting surface 305 (hereinafter sometimes referred to as a “parabolic surface”) having a shape obtained by cutting a parabolic surface with a meridian plane. The reflector 300 reflects the divergent light emitted from the LED 14 by the reflecting surface 305 (parabolic surface) described above, converts it into substantially parallel light, and makes the converted light enter the end face of the light guide 311. In one specific example, the light guide 311 is a transmissive light guide.

[0123] The reflecting surface of the reflector 300 has 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 an LED at the focus of such a parabolic surface, the light flux after reflection is converted into substantially parallel light.

[0124] Since the LED 14 is a surface light source, it is not possible to convert the divergent light from the LED into completely parallel light even when it is arranged at the focus of the parabolic surface, but this does not affect the performance of the light source of the present invention. The LED 14 and the reflector 300 form a pair, and in order to ensure a predetermined performance at the mounting accuracy of the LED on the substrate 102 of ±40 μm, the number of LEDs mounted on the substrate should be at most 10 or less, and it is preferable to limit it to about 5 in consideration of mass productivity.

[0125] The LED 14 and the reflector 300 are in proximity to each other in part, but heat can be dissipated into the space on the opening side of the reflector 300, so that 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 a glass material, so that the light utilization efficiency can be improved.

[0126] On one hand, a reflecting surface is provided on the bottom surface 303 of the light guide 311. The light from the LED 14 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 disposed 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.

[0127] Further, 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.

[0128] As shown in FIG. 26, the refracting surface 314 may have a plurality of surfaces with different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces with different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300. The inclination of the plurality of surfaces refracts 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 refracting surface 314 may also be a transmissive surface.

[0129] 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 refracting surface 314. That is, the extending directions of the plurality of surfaces with different inclinations of the refracting 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 light angle 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.

[0130] Further, 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 radiated into the air, improving the cooling effect. As a result, the operating temperature of the LED can be reduced, thereby maintaining the luminous efficiency and extending the service life.

[0131] <Another example 2 of the light source device> Subsequently, with respect to the light source device shown in FIG. 26, the optical system configuration of a light source device with a 1.8-fold improvement in light utilization efficiency using polarization conversion 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 in FIG. 27A(1) is omitted.

[0132] FIGS. 27A, 27B, and 27C show a state in which the LEDs 14 constituting the light source are provided on the substrate 102. These are configured by a unit 312 having a pair of blocks of the reflector 300 and the LEDs 14 and a plurality of blocks.

[0133] 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 and the shape of the reflecting surface of the reflector 300 may be the same as those in the example of the light source device in FIG. 26.

[0134] Further, 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. This reason will be explained 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 disposed at the focal position of the paraboloid.

[0135] Also, due to the characteristics of the parabolic surface, the light emitted from the four corners of the light-emitting surface also becomes a substantially parallel light beam, and only the emission directions are different. Therefore, even if the light-emitting part 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.

[0136] Also, even if the mounting position of the LED 14 is shifted 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 the light conversion efficiency for the reasons described above. Furthermore, even when the mounting positions of the LEDs 14 vary in the Z-axis direction, the converted parallel light beam only moves within the ZX plane, and the mounting accuracy of the surface light source LEDs can be significantly reduced. Although the reflector 300 having a reflecting surface with a part of the parabolic surface cut out meridionally has been described in this embodiment, an LED may be arranged on a part where the entire parabolic surface is cut out as the reflecting surface.

[0137] On the other hand, in this embodiment, as shown in FIGS. 27B(1) and 27C, the divergent light 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. With this characteristic configuration, in the present invention, the light utilization efficiency is 1.8 times that of the example shown in FIG. 26 described above, and a highly efficient light source can be realized.

[0138] At this time, the substantially parallel light obtained by reflecting the divergent light from the LED 14 by the parabolic surface 321 is not all uniform. Therefore, by adjusting the angular distribution of the reflected light by the reflecting surfaces 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.

[0139] Here, in the example of this figure, the light (principal ray) entering the reflector from the LED and the light entering the liquid crystal display panel are arranged to be substantially parallel. This arrangement is easy to arrange in terms of design, and it is more preferable to arrange the heat source under the light source device because the air can escape upward, thereby reducing the temperature rise of the LED.

[0140] Also, as shown in FIG. 27B(1), in order to improve the light capture rate of the 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 disposed 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.

[0141] Thus, the substantially parallel light beam aligned in a specific polarization by the polarization conversion element 21 is reflected toward the liquid crystal display panel 11 disposed to face the light exit surface of the reflective light guide 306 by the reflection shape provided on the surface of the reflective light guide 306. At this time, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is determined by the prior setting or adjustment (optimal design) of the shape and arrangement of the reflector 300, the reflection surface shape (cross-sectional shape) of the reflective light guide, the inclination of the reflection surface, the surface roughness, etc. described above. In other words, by optimizing the above-described setting or adjustment items, the light quantity distribution of the light beam incident on the liquid crystal display panel 11 is optimized.

[0142] As the reflection surface shape provided on the surface of the light guide 306, a plurality of reflection surfaces are arranged to face the light exit surface of the polarization conversion element, and according to the distance from the polarization conversion element 21, the inclination, area, height, and pitch of the reflection surface are optimized, 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.

[0143] As shown in Fig. 27B(2), the reflecting surface 307 provided on the reflective light guide can be 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 the reflecting surface has a plurality of inclinations on one surface, the area used as the reflecting 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 reflecting surface.

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

[0145] 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 as shown in Figs. 27A, 27B, and 27C.

[0146] However, when the substrate 102 is arranged upward, since the substrate 102 becomes close to the liquid crystal display panel 11, the layout may become difficult. Therefore, as shown in the figure, arranging the substrate 102 below the reflector 300 (the side far from the liquid crystal display panel 11) makes the configuration inside the device simpler.

[0147] On the light incident surface of the polarization conversion element 21, a light shielding plate 410 may be provided 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, for a light beam with aligned polarization, the temperature rise can be reduced by absorption, and for a part of the light whose polarization direction rotates when reflected by the reflective light guide, it is absorbed by the incident-side polarizing plate. Further, although the temperature of the liquid crystal display panel 11 also rises due to absorption in the liquid crystal itself and temperature rise caused by light incident on the electrode pattern, since there is a sufficient space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11, the temperature rise of the liquid crystal display panel 11 can be suppressed by natural cooling using such a space.

[0148] FIG. 27D is a modified example of the light source device of FIGS. 27B(1) and 27C. FIG. 27D(1) illustrates a modified example by extracting a part of the light source device of FIG. 27B(1). Since the other configurations are the same as those of the light source device described above with reference to FIG. 27B(1), the illustration and repeated description are omitted.

[0149] First, in the example shown in FIG. 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 FIG. 27D(1)) passes out of the concave portion 319 of the sub-reflector 310 and is at a position lower than that of 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 enters the effective region of the polarization conversion element 21 without being blocked by the light shielding plate 410.

[0150] 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 region of the subsequent polarization conversion element 21, thereby further improving the light utilization efficiency.

[0151] 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 is arranged periodically along one direction. By adopting such an uneven shape, the main light ray of the fluorescence output laterally from the phosphor 114 can be configured to be incident on the effective region of the polarization conversion element 21.

[0152] In addition, 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.

[0153] In addition, 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 main light ray of the fluorescence output laterally from the phosphor 114 is not blocked by the light shielding body 410 and is incident on the effective region of the polarization conversion element 21. 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.

[0154] 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.

[0155] 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 on the right side from 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 is provided with a reflective region having a reflective film. By making the surface of the side wall 400 in the above 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.

[0156] 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.

[0157] 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, these light source devices may be configured by omitting the polarization conversion element 21. In this case, the light source device can be provided at a lower cost.

[0158] <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.

[0159] FIG. 28A shows a state in which the LED 14 constituting the light source is 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 a 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.

[0160] 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 in 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.

[0161] 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.

[0162] <Another Example 4 of the Light Source Device> Next, the light source device in 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 of 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).

[0163] Figure 29 shows a 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)).

[0164] 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.

[0165] The light emitted from the LED 14 is incident on the polarization conversion element 501 via the collimator 18. In this example, 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.

[0166] 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. Further, 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 set to a desired value (optimized) as described above.

[0167] The reflecting surface provided on the reflective light guide is configured such that one surface (the region for reflecting light), similar to the reflective light guide described in 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 composed of different inclined surfaces), so that the reflected light can be adjusted with higher precision. 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, by providing the light shielding wall 507, it is possible to prevent the generation of leakage light in directions other than the desired direction (the direction toward the liquid crystal display panel 11).

[0168] 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 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).

[0169] FIG. 30 is a cross-sectional view showing an example of the shape of the diffusion plate 206. As described above, the divergent light emitted from the LED is converted into substantially parallel light by the reflector 300 or the collimator 18, and after being converted into a specific polarization wave by the polarization conversion element 21, it is reflected by the light guide. Then, 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 arrows indicating "reflected light from the light guide" in FIG. 30).

[0170] 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 like this, it becomes possible to effectively utilize the polarization-converted light beam.

[0171] <Lenticular lens> As a method for adjusting the diffusion distribution of the video light from the liquid crystal display panel 11, a lenticular lens may be 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 may be optimized. That is, by optimizing the shape of the lenticular lens, the emission characteristics of the video light (hereinafter also referred to as "video light beam") emitted from the liquid crystal display panel 11 in one direction can be adjusted.

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

[0173] 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 video light beam emitted from the video display device 1 are adjusted (optimized) through the lenticular lens, and the optimized video light beam is efficiently transmitted or reflected by the windshield 105 to obtain a suitable floating image in space.

[0174] As a further configuration example, two lenticular lenses may be arranged in combination at the position where the video light emitted from the video 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 video light can be adjusted according to the reflection angle of the video light (the reflection angle with respect to the case of reflection in the vertical direction as the reference (0 degrees)) in the X-axis and Y-axis directions.

[0175] In this embodiment, by using such a lenticular lens, as shown in the graphs (plot curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in FIG. 22(B), excellent optical characteristics that are clearly different from the graph (plot curve) of the conventional characteristics can be obtained. 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.

[0176] Therefore, according to this embodiment, for video light from a surface-emitting laser video source, which has a narrow diffusion angle (high straightness) 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 images generated in the retroreflective member and adjust so that the spatial floating images due to retroreflection can efficiently reach the viewer's eyes.

[0177] Also, 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. 22(a) and (b), it is possible to give a significantly angled directivity characteristic in both the X-axis direction and the Y-axis direction. In this embodiment, by giving such a narrow-angle directivity characteristic, 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.

[0178] FIG. 21 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 of the light emission direction is at an angle of around 30 degrees upward from the vertical direction (0 degrees), showing a vertically symmetric luminance characteristic. Further, the plot curves of characteristics A and B shown in the graph of FIG. 21 show examples of characteristics in which the video light above the peak luminance is condensed at around 30 degrees to increase the luminance (relative luminance). Therefore, in these characteristics A and B, 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.

[0179] That is, according to the optical system including the lenticular lens described above, when the video light beam from the video display device 1 is incident on the retroreflective member 2, the emission angle and the viewing angle of the video light aligned at the included angle by the light source device 13 can be adjusted, and the degree of freedom in installing the retroreflective sheet 2 can be greatly 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 through the windshield 105 and imaged at a desired position can be greatly improved. As a result, it becomes possible to efficiently reach the eyes of outdoor or indoor viewers as light with a narrow diffusion angle (high straight-aheadness) and only a specific polarization component. According to this, even if the intensity (luminance) of the video light from the video display device 1 is reduced, the viewer can accurately recognize the video light and obtain information. In other words, by reducing the output of the video display device 1, it becomes possible to realize an information display system with low power consumption.

[0180] 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.

[0181] 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 HUD, tablet, digital signage, etc.

[0182] 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, a user can 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 is possible to reduce the risk of contact infection of infectious diseases and provide a non-contact user interface that can be used without feeling anxiety. According to the present invention that provides such technology, it contributes to "3 Good health and well-being for all" among the Sustainable Development Goals (SDGs) proposed by the United Nations.

[0183] Also, 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.

[0184] Furthermore, in the technology according to the above-described embodiment, it is possible to form a spatial floating image using video light with high directivity (linearity). In the technology according to this embodiment, even when displaying images that require high security in bank ATMs, ticket vending machines at stations, etc., or images with high confidentiality that need to be concealed from people facing the user directly, by displaying video light with high directivity, it is possible to provide a non-contact user interface with less risk of the spatial floating image being spied on by 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.

Description of Reference Numerals

[0185] 1…Image display device, 2…Retroreflective member, 3…Spatial image (spatial floating image), 105…Windshield, 100…Transparent plate, 101…Polarization beam splitter, 12…Absorptive polarizer, 13…Light source device, 54…Light direction conversion panel, 151…Retroreflective member, 102, 202…LED substrate, 203…Light guide, 205…Reflective sheet, 271…Reflector, 206, 270…Phase difference plate, 300…Spatial floating image, 301…Ghost image of spatial floating video, 302…Ghost image of spatial floating video, 11…Liquid crystal display panel, 206…Diffuser, 21…Polarization conversion element, 300…LED reflector, 213…λ / 2 plate, Reflective light guide…306, Reflective surface…307, Sub-reflector…308, 310, 81…Optical element, Polarization conversion element…501, Unit…503, Light-shielding wall…507, 401, 402…Light-shielding plate, 320…Substrate

Claims

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Images