JP7165792B1 - Spatial floating image information display system and light source device used therefor - Google Patents

Abstract

An object of the present invention is to suitably display an image to the outside of a space. According to the present invention, the Sustainable Development Goals "3 Good Health and Welfare for All", "9 Industrial and Technological Innovation Infrastructures", and "11 Sustainable Cities and Communities" can be achieved. A spatially floating image display device includes a display panel for displaying an image, a light source device, and recursive properties in which image light from the display panel is reflected, and the reflected light is used to display a real spatially floating image in the air. and a reflector, wherein the light source device includes a point-like or planar light source, a reflector that reflects light from the light source, and a light guide that guides the light from the reflector toward the display panel. and, the reflecting surface of the reflector has an asymmetrical shape with respect to the optical axis of the light emitted from the light source. [Selection drawing] Fig. 27B

Description

The present invention relates to a spatial floating image information display system and a light source device used therein.

As spatial floating information display systems, image display devices that display images directly toward the outside and display methods that display images as spatial screens are already known. Further, for example, Patent Document 1 discloses a detection system that reduces erroneous detection of operations on an operation surface of a displayed aerial image.

JP 2019-128722 A

However, as a method of reducing erroneous detection of the spatial floating image information display system of the prior art and manipulation of the spatial image, optimization technology for design including the light source of the image display device that is the image source of the spatial floating image is considered. It has not been.

An object of the present invention is to provide a spatial floating information display system or a spatial floating image display device with suitable images that have high visibility (visual resolution and contrast) and reduce erroneous detection of manipulation of the displayed spatial image. To provide a technique capable of displaying.

In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above problems, and a spatial floating image display device is given below as an example thereof. A spatially floating image display device as an example of the present application includes a display panel for displaying images, a light source device, and recursive properties that reflect image light from the display panel and display a real spatially floating image in the air by the reflected light. and a reflector. Here, the light source device includes a point-like or planar light source, a reflector that reflects light from the light source, and a light guide that guides the light from the reflector toward the display panel. The surface has an asymmetrical shape with respect to the optical axis of the light emitted from the light source.

According to the present invention, it is possible to realize a spatially floating information display system or a spatially floating image display device that can suitably display spatially floating image information and has a sensing function with less false detection. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of usage of a spatially floating image information display system according to an embodiment of the present invention; It is a figure which shows an example of a principal part structure and a retroreflection part structure of the spatial floating image information display system which concerns on one Example of this invention. FIG. 10 is a diagram showing another example of the main configuration of the spatially floating image information display system according to one embodiment of the present invention; FIG. 10 is a diagram showing another example of the main configuration of the spatially floating image information display system according to one embodiment of the present invention; FIG. 4 is an explanatory diagram for explaining functions of a sensing device used in the spatially floating image information display system; FIG. 2 is an explanatory diagram of the principle of three-dimensional image display used in the spatially floating image information display system; FIG. 2 is an explanatory diagram of a measurement system for evaluating the characteristics of a reflective polarizing plate; FIG. 4 is a characteristic diagram showing the transmittance characteristic of the transmission axis of the reflective polarizing plate with respect to the light incident angle; FIG. 4 is a characteristic diagram showing transmittance characteristics of a reflection axis of a reflective polarizing plate with respect to a light incident angle; FIG. 4 is a characteristic diagram showing the transmittance characteristic of the transmission axis of the reflective polarizing plate with respect to the light incident angle; FIG. 4 is a characteristic diagram showing transmittance characteristics of a reflection axis of a reflective polarizing plate with respect to a light incident angle; It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. 1 is a layout diagram showing main parts of a spatial floating image information display system according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing the configuration of an image display device that constitutes a spatially floating image information display system according to an embodiment of the present invention; FIG. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. FIG. 4 is an explanatory diagram for explaining light source diffusion characteristics of an image display device; FIG. 4 is an explanatory diagram for explaining diffusion characteristics of an image display device; FIG. 4 is an explanatory diagram for explaining diffusion characteristics of an image display device; 1 is a cross-sectional view showing the configuration of an image display device that constitutes a spatially floating image information display system; FIG. FIG. 10 is an explanatory diagram for explaining the principle of generation of a ghost image that occurs in a conventional spatially floating image information display system; 1 is a cross-sectional view showing the configuration of an image display device that constitutes a spatially floating image information display system according to an embodiment of the present invention; FIG. It is a figure which shows another example of the concrete structure of a light source device. It is a figure which shows another example of the concrete structure of a light source device. FIG. 4 is a cross-sectional view showing another example of a specific configuration of the light source device; FIG. 4 is a cross-sectional view showing another example of a specific configuration of the light source device; It is the figure which extracted a part of another example of the concrete structure of a light source device. It is a figure which shows another example of the concrete structure of a light source device. FIG. 4 is a cross-sectional view showing another example of a specific configuration of the light source device; It is a figure which shows another example of the concrete structure of a light source device. FIG. 7 is a cross-sectional view of an example of the shape of a diffusion plate in another example of the specific configuration of the light source device;

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

In addition, in the drawings for explaining the present invention, the same reference numerals are given to those having the same or similar functions, and different names are used as appropriate, while repetitive descriptions of functions etc. are omitted. There is In the following description of the embodiments, an image floating in space is expressed by the term "space floating image". Instead of this term, expressions such as "aerial image", "aerial image", "floating in air", "floating in space optical image of displayed image", "floating in air optical image of displayed image", etc. may be used. The term “space floating image” mainly used in the description of the embodiments is used as a representative example of these terms.

For example, the present disclosure transmits an image by image light from a large-area image light source through a transparent member that partitions a space, such as glass of a show window, and floats inside or outside a store (space). The present invention relates to an information display system capable of displaying images. The present disclosure also relates to a large-scale digital signage system configured using a plurality of such information display systems.

According to the following embodiments, for example, it is possible to display high-resolution video information in a space-floating state on the glass surface of a show window or a light-transmitting plate. At this time, by making the divergence angle of the emitted image light small, that is, by making it acute, and by aligning it with a specific polarized wave, it is possible to efficiently reflect only normal reflected light on the retroreflective member. As a result, the efficiency of light utilization is high, and the ghost image that occurs in addition to the main space floating image, which has been a problem with the conventional retroreflection method, can be suppressed, and a clear space floating image can be obtained.

In addition, the device including the light source of the present disclosure can provide a novel and highly usable spatial floating image information display system capable of significantly reducing power consumption. In addition, according to the technology of the present disclosure, for example, it is possible to display a so-called unidirectional spatial floating image that is visible outside the vehicle through shield glass including the windshield, rear glass, and side glass of the vehicle. A floating image information display system for vehicles can be provided.

On the other hand, in a conventional spatial floating image information display system, an organic EL panel or liquid crystal display panel (liquid crystal panel or display panel) is combined with a retroreflective member 151 as a high-resolution color display image source 150 . In the conventional spatial floating image display device, image light is diffused over a wide angle. Ghost images (see reference numerals 301 and 302 in FIG. 23) are generated by the image light incident obliquely on 2a, and the image quality of the spatially floating image is impaired. Further, in the conventional spatial floating image display device, as shown in FIG. 23, in addition to the normal spatial floating image 300, a plurality of first ghost images 301, second ghost images 302, and the like are generated. As a result, the image floating in the same space, which is a ghost image, can be viewed by people other than the viewer, which poses a serious problem from the viewpoint of security.

<First Configuration Example of Spatial Floating Image Information Display System>
FIG. 1A is a diagram showing an example of a usage pattern of the spatially floating image information display system of the present disclosure. FIG. 1A is a diagram for explaining the overall configuration of the spatially floating image information display system according to this embodiment. Referring to FIG. 1A, for example, in a store or the like, a space is partitioned by a show window (also referred to as "window glass") 105, which is a translucent member such as glass. According to the spatial floating information display system of the present disclosure (hereinafter also referred to as "this system"), it is possible to transmit such a transparent member and display a floating image in one direction to the outside of the store (space). It is possible.

Specifically, according to this system, light with narrow-angle directional characteristics and specific polarization is emitted from an image display device (display device) 1 as an image light flux, once incident on a retroreflective member 2, and retroreflected. The light is reflected and transmitted through the window glass 105 to form an aerial image 3 (space floating image 3), which is a real image, outside the store. In FIG. 1A, the inside (the inside of the store) of the transparent member (here, the window glass) 105 is the depth direction, and the outside of the window glass 105 (for example, the sidewalk) is shown in front.

On the other hand, it is also possible to provide a means for reflecting a specific polarized wave on the window glass 105, reflect the image light flux by such means, and form an aerial image at a desired position in the store.

FIG. 1B is a block diagram showing the configuration of the video display device 1 described above. The video display device 1 includes a video display unit that displays an original aerial image, a video control unit that converts the input video to match the resolution of the panel, and a video signal reception unit that receives video signals. .

Among these, the video signal receiving unit, for example, corresponds to a wired input signal through an input interlace such as HDMI (High-Definition Multimedia Interface (registered trademark)) and Wi-Fi (registered trademark) (Wireless Fidelity) It plays a role of responding to wireless input signals such as. Also, the video signal receiving section can function independently as a video receiving/displaying device. Furthermore, the video signal receiving section can also display video information from a tablet, smartphone, or the like. Furthermore, the video signal receiving section can be connected to a processor (arithmetic processing unit) such as a stick PC as necessary. You can also have it.

FIG. 2 is a diagram showing an example of the configuration of the main part and the configuration of the retroreflection part of the spatial floating image information display system of the present disclosure. The configuration of the spatially floating image information display system will be described more specifically with reference to FIG. As shown in FIG. 2A, a transparent plate (hereinafter referred to as "transparent member") 100 made of glass or the like has light-transmitting properties. A video display device 1 is provided. The image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates specific polarized light having narrow-angle diffusion characteristics.

Image light of a specific polarized wave from the image display device 1 is transmitted through a polarization separation member 101 (in the drawing, the polarization separation member 101 is a sheet) having a film that selectively reflects the image light of the specific polarized wave provided on the transparent member 100. formed into a shape and adhered to the transparent member 100 ), and is incident on the retroreflective member 2 . A λ/4 plate 21 is provided on the image light incident surface of the retroreflective member. The image light is passed through the λ/4 plate 21 twice, when it enters the retroreflective member and when it exits, so that the specific polarized wave is polarization-converted into the other polarized wave.

Here, since the polarization separation member 101 that selectively reflects the image light of the specific polarized wave has the property of transmitting the polarized light of the other polarized wave after the polarization conversion, the image light of the specific polarized wave after the polarization conversion is , passes through the polarization separation member 101 . The image light transmitted through the polarization separation member 101 forms a space floating image 3 which is a real image outside the transparent member 100 .

The light that forms the floating image 3 is a set of light rays converging from the retroreflective member 2 to the optical image of the floating image 3, and these light rays travel straight even after passing through the optical image of the floating image 3. do. Therefore, the floating image 3 is an image having high directivity, unlike diffuse image light formed on a screen by a general projector or the like.

Therefore, in the configuration of FIG. 2, the floating image 3 is viewed as a bright image when viewed by the user from the direction of the arrow A, but when viewed by another person from the direction of the arrow B, the floating image 3 is viewed as a bright image. Image 3 cannot be visually recognized as an image at all. This characteristic is very suitable for use in a system that displays a video that requires high security or a highly confidential video that should be kept secret from a person facing the user.

Depending on the performance of the retroreflective member 2, the polarization axes of the reflected image light may become uneven. In this case, part of the image light whose polarization axes are not aligned is reflected by the polarization separation member 101 described above and returns to the image display device 1 . A part of this image light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the image display device 1, and by generating a ghost image, it can be a cause of deterioration of the image quality of the spatial floating image.

Therefore, in the present embodiment, the image display surface of the image display device 1 is provided with the absorptive polarizing plate 12 . The absorptive polarizer 12 transmits the image light emitted from the image display device 1 and absorbs the reflected light returning from the polarization separation member 101. , can suppress re-reflection. Therefore, according to the present embodiment using the absorptive polarizing plate 12, it is possible to prevent or suppress deterioration in image quality due to ghost images of spatially floating images.

The polarization separating member 101 described above may be formed of, for example, a reflective polarizing plate or a metal multilayer film that reflects a specific polarized wave.

Next, FIG. 2(B) shows the surface shape of the retroreflective member manufactured by Nippon Carbide Industry Co., Ltd. used in this study as a representative retroreflective member 2 . Light rays incident on the inside of the regularly arranged hexagonal prisms are reflected by the wall surface and the bottom surface of the hexagonal prisms and emitted as retroreflected light in the direction corresponding to the incident light. It displays a spatial floating image. The resolution of this spatially floating image largely depends on the resolution of the liquid crystal display panel 11 as well as the outer shape D and the pitch P of the retroreflective portion of the retroreflective member 2 shown in FIG. 2(B). For example, when using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is about 80 μm, for example, 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. For this reason, the effective resolution of the spatially floating image is reduced to about 1/3. Therefore, in order to make the resolution of the spatially floating image equal to that of the image display device 1, it is desired that the diameter and pitch of the retroreflecting portions be made close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the generation of moire by the pixels of the retroreflective member and the liquid crystal display panel, it is preferable to design the respective pitch ratios outside the integral multiple of one pixel. In addition, it is preferable that the shape of the retroreflective portion is arranged so that no one side of the retroreflective portion overlaps any one side of one pixel of the liquid crystal display panel.

On the other hand, in order to manufacture the retroreflective member at a low cost, it is preferable to use a roll press method for molding. Specifically, it is a method of aligning the retroreflecting parts and shaping them on the film. Forming the reverse shape of the shape to be shaped on the roll surface, applying UV curable resin on the base material for fixing, and separating the rolls By passing it through, it is shaped into a desired shape and cured by irradiation with ultraviolet rays to obtain the retroreflective member 2 of a desired shape.

<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 image information display system according to one embodiment of the present invention. FIG. 3A is a diagram showing another embodiment of the spatial floating image information display system. The image display device 1 includes a liquid crystal display panel 11 as an image display element 11 and a light source device 13 that generates specific polarized light having narrow-angle diffusion characteristics. The liquid crystal display panel 11 is composed of a small liquid crystal display panel having a screen size of about 5 inches to a large liquid crystal display panel having a screen size exceeding 80 inches. For example, a polarization separation member 101 such as a reflective polarizing plate reflects image light from a liquid crystal display panel toward a retroreflection member (retroreflection portion or retroreflection plate) 2 .

The difference between the example shown in FIG. 3 and the example shown in FIG. 2 is that the reflective sheet is provided along the convex shape. Therefore, the image light from the liquid crystal display panel 11 is diffused according to the shape of the concave surface and enters the retroreflective member 2 . As a result, it is possible to obtain the spatially floating image 3 which is a real image expanded and enlarged from the screen display surface of the liquid crystal display panel 11 (the display size is L1 in the drawing). Furthermore, after the image light beam reflected by the retroreflective member 2 is polarized and converted, it is transmitted through the convex reflecting sheet, then further diffused by the action of the concave surface provided on the other surface of the convex surface, and transmitted through the transparent member 100, This results in a spatially floating image L2 enlarged obliquely in FIG. 3(A). At this time, the magnification M of the spatial floating image is M=L2/L1.

As described above, an optical member having a lens action is provided between the image display element 11 and the retroreflection member 2 or between the retroreflection member 2 and the spatially floating image. By decentering or tilting from the optical axis connecting the retroreflective members, the size and imaging position of the spatially floating image obtained in the image information system can be arbitrarily set with respect to the optical axis described above. As described above, if the size and imaging position of the image floating in space are changed by the optical member, the spatial image will be distorted as it is. You can get images without distortion.

A λ/4 plate 21 is provided on the light incident surface of the retroreflection member 2, and incident image light is reflected by the retroreflection member 2 and then transmitted through the λ/4 plate 21 again, thereby converting the polarization of the image light. It is transmitted through the polarized light splitting member 101 having a convex surface. As a result, it is possible to form a spatially floating image of a size different from the size displayed on the liquid crystal display panel at a position transmitted through the transparent member 100 .

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

Here, as explained in FIG. 2, since the floating image 3 is formed by light rays having high directivity, the floating image 3 is visually recognized as a bright image when viewed from the direction of the arrow A. When viewed from the direction of arrow B, the floating image 3 is not viewed as a video at all. Therefore, in the configuration of FIG. 3B , the floating image 3 is positioned behind the virtual image X when the user views it from the direction of the arrow B, but the user does not see the floating image 3 at all. It is not visually recognized, and only the virtual image X is suitably visually recognized. Therefore, by making use of this characteristic, as shown in FIG. This is preferable because the entire system can be made smaller than when the floating image 3 is excluded.

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

A λ/4 plate 21 is provided on the light incident surface of the retroreflecting member 2, and passes the image light twice to convert the polarization of the specific polarized wave into the other polarized wave with a phase difference of 90°. As a result, the retroreflected image light is transmitted through the polarization separation member 101 and the space floating image 3 as a real image is displayed outside the transparent member 100 . Here, since the polarization axes become uneven due to retroreflection in the polarization separation member 101 described above, part of the image light is reflected back to the image display device 1 . This light is reflected again by the image display surface of the liquid crystal display panel 11 that constitutes the image display device 1, generating a ghost image and significantly degrading the image quality of the spatially floating image.

Therefore, in this embodiment, the absorptive polarizing plate 12 is provided on the image display surface of the image display device 1 . This absorptive polarizing plate 12 transmits the image light emitted from the image display device 1 and absorbs the reflected light from the polarization separation member 101 described above. To prevent deterioration of image quality due to images. Also, in order to reduce deterioration in image quality due to sunlight or illumination light outside the set, it is preferable to provide an absorptive polarizing plate 102 on the surface of the transparent member 105 on the image light output side.

Next, a sensor 44 having a TOF (Time of Fly) function is installed in FIG. 5, it is possible to detect not only the coordinates in the planar direction of the object but also the coordinates in the depth direction and the direction and speed of movement of the object.

In order to read two-dimensional distance and position, multiple combinations of invisible light emitters such as infrared rays or ultraviolet rays and light receivers are arranged in a straight line. light is received at the The product of the difference between the time the light was emitted and the time the light was received and the speed of light gives the distance to the object. Further, the coordinates on the plane can be read from the coordinates at the portion where the difference between the light emitting time and the light receiving time is the smallest among the plurality of light emitting units and light receiving units. As described above, three-dimensional coordinate information can also be obtained by combining the coordinates of a target object on a plane (two-dimensional) with a plurality of sensors described above.

Furthermore, a method for obtaining a three-dimensional spatial floating image as the spatial floating image information system described above will be described with reference to FIG. 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 video display screen of the liquid crystal display panel 11 of the video display device 1 shown in FIG. As a result, as shown in FIG. 6, in order to display motion parallaxes from three directions of motion parallaxes P1, P2, and P3 in the horizontal direction of the screen, images from three directions are made into one block every three pixels, and one pixel Image information from three directions is displayed for each, and the direction of light emission is adjusted by the action of the corresponding lenticular lens (indicated by vertical lines in FIG. 6) to separate and emit light in three directions. As a result, a three-parallax stereoscopic image can be displayed.

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

In the characteristic graphs of FIGS. 8 to 11 (indicated in color), the values of angles (deg) shown in the margins on the right side are shown on the vertical axis, that is, in descending order of transmittance (%) from the top. showing. 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 highest when the angle in the vertical (V) direction is 0 degrees (deg), 10 degrees, 20 degrees, The transmittance decreases in the order of 30 degrees and 40 degrees. 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 degree (deg), 10 degrees, 20 degrees, The transmittance decreases in the order of 30 degrees and 40 degrees.

In FIG. 10, in the range where the horizontal axis indicates light with a wavelength of approximately 400 nm to 800 nm, the transmittance is highest when the angle in the horizontal (H) direction is 0 degrees (deg), and when the angle is 10 degrees and 20 degrees. Transmittance decreases in order. In FIG. 11, in the range where the horizontal axis indicates light with a wavelength of approximately 400 nm to 800 nm, the transmittance is highest when the angle in the horizontal (H) direction is 0 degrees (deg), and when the angle is 10 degrees and 20 degrees. Transmittance decreases in order.

As shown in FIGS. 8 and 9, the grid-structured reflective polarizer has degraded characteristics for light from a direction perpendicular to the polarization axis. For this reason, specifications along the polarization axis are desirable, and the light source of this embodiment, which can emit image light emitted from the liquid crystal display panel 11 at a narrow angle, is an ideal light source. Similarly, the characteristics in the horizontal direction also deteriorate with respect to oblique light. In consideration of the above characteristics, a configuration example of this embodiment in which a light source capable of emitting image light from the liquid crystal display panel 11 at a narrower angle is used as the backlight of the liquid crystal display panel 11 will be described below. This makes it possible to provide high-contrast spatial floating images.

<Video display device>
Next, the image display device 1 of this embodiment will be described with reference to the drawings. The image display device of this embodiment includes an image display element 11 (liquid crystal display panel) and a light source device 13 constituting the light source. FIG. ing.

This liquid crystal display panel (image display element 11) has, as indicated by an arrow 30 in FIG. ) is strong and the polarization plane is aligned in one direction. It transmits through the window glass 105 and forms a spatially floating image that is a real image (see also FIG. 1).

12, a liquid crystal display panel 11 constituting the image display device 1, a light direction conversion panel 54 for adjusting the directivity of the light flux emitted from the light source device 13, and a narrow angle diffusion plate ( not shown). That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and image light of a specific polarized wave is emitted after modulating the intensity of the light according to the image signal (see arrow 30 in FIG. 12). . As a result, a desired image is projected toward the retroreflective member 2 through the light direction conversion panel 54 as light of a specific polarized wave with high directivity (straightness). A space floating image 3 is formed by transmitting toward the viewer's eyes outside (space). A protective cover 50 (see FIGS. 13 and 14) may be provided on the surface of the light direction conversion panel 54 described above.

In this embodiment, in order to improve the utilization efficiency of the light flux 30 emitted from the light source device 13 and to significantly reduce the power consumption, the image display device 1 including the light source device 13 and the liquid crystal display panel 11 includes: Light from the light source device 13 (see arrow 30 in FIG. 12) is projected toward the retroreflective member 2, reflected by the retroreflective member 2, and then projected onto a transparent sheet (not shown) provided on the surface of the window glass 105. ), the directivity can also be adjusted to form the floating image at the desired position.

Specifically, this transparent sheet adjusts the imaging position of the floating image while providing high directivity by optical parts such as a Fresnel lens and a linear Fresnel lens. According to this, the image light from the image display device 1 efficiently reaches the observer outside the window glass 105 (for example, sidewalk) with high directivity (straightness) like a laser beam. As a result, it is possible to display a high-quality floating image with high resolution, and to significantly reduce the power consumption of the image display device 1 including the LED elements 201 of the light source device 13 .

<Example 1 of image display device>
FIG. 13 shows an example of a specific configuration of the image display device 1. As shown in FIG. In FIG. 13, the liquid crystal display panel 11 and the light direction changing panel 54 are arranged on the light source device 13 of FIG. The light source device 13 is made of plastic, for example, on the case shown in FIG. As shown in FIG. 12 and the like, the end face of the light guide 203 is gradually cut off toward the light receiving part in order to convert the diverging light from each LED element 201 into a substantially parallel light flux. A lens shape is provided that has a shape that increases the area and that has the effect of gradually decreasing the divergence angle by performing total reflection multiple times while propagating inside.

A liquid crystal display panel 11 is attached on the light guide 203 . In addition, 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 as a semiconductor light source and an LED substrate 202 on which a control circuit thereof is mounted are attached. A heat sink, which is a member for cooling the heat generated by the LED elements and the control circuit, may be attached to the outer surface of the LED substrate 202 .

In addition, 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 is electrically connected to the liquid crystal display panel 11 attached to the frame and further to the liquid crystal display panel 11 . FPCs (Flexible Printed Circuits) (not shown) and the like are attached. That is, the liquid crystal display panel 11, which is an image display element, along with the LED element 201, which is a solid-state light source, modulates the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes the electronic device. to generate the display image. At this time, the generated image light has a narrow diffusion angle and only a specific polarized wave component, so a new image display device that has not existed in the past, which is similar to a surface emitting laser image source driven by a video signal, can be obtained. .

At present, it is technically and safely impossible to obtain a laser beam having the same size as the image obtained by the image display device 1 using a laser device. Therefore, in this embodiment, for example, light close to the above-described surface emitting laser image light is obtained from a luminous flux from a general light source provided with an LED element.

Next, the configuration of the optical system housed in the case of the light source device 13 will be described in detail with reference to FIGS. 13 and 14. FIG.

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 surface 203a of the light guide 203. . For this reason, the light receiving portion on the end surface of the light guide and the LED element are attached while maintaining a predetermined positional relationship.

Each of the light guides 203 is made of translucent resin such as acryl. The LED light receiving surface at the end of the light guide 203 has, for example, a conical convex outer peripheral surface obtained by rotating the parabolic cross section, and the top has a convex portion in the center (that is, In the center of the plane portion, there is a convex lens surface projecting outward (or a concave lens surface recessed inward) (not shown). The outer shape of the light receiving portion of the light guide to which the LED element 201 is attached has a parabolic shape forming a conical outer peripheral surface, and the light emitted from the LED element in the peripheral direction can be totally reflected inside. It is set within the range of possible angles, or a reflective surface is formed.

On the other hand, the LED elements 201 are arranged at predetermined positions on the surface of an LED board 202, which is the circuit board. The LED substrate 202 is arranged and fixed to the collimator (light receiving end surface 203a) so that the LED elements 201 on the surface thereof are positioned in the central portion of the recesses described above.

According to such a configuration, the shape of the light receiving end surface 203a of the light guide 203 makes it possible to extract the light emitted from the LED element 201 as substantially parallel light, thereby improving the utilization efficiency of the generated light. Become.

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 the light receiving end surface 203a, which is a light receiving portion provided on the end surface of the light guide 203. is converted into substantially parallel light by the lens shape of the light receiving end face 203a of the light guide body end face, and guided inside the light guide body 203 as indicated by the arrow (in the direction parallel to the drawing). , toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (direction perpendicular to the front of the drawing). By optimizing the distribution (density) of the luminous flux direction changing means 204 according to the shape of the interior or surface of the light guide, the uniformity of the luminous flux incident on the liquid crystal display panel 11 can be adjusted.

As shown in FIG. 13 or FIG. 14, the above-described luminous flux direction changing means 204 can change the luminous flux propagating in the light guide 203 by providing a portion having a different refractive index, for example, in the shape of the surface of the light guide or in the interior of the light guide. is emitted toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front of the drawing). At this time, when the liquid crystal display panel 11 faces the center of the screen and the viewpoint is placed at the same position as the diagonal dimension of the screen, the relative brightness ratio of the center of the screen and the peripheral part of the screen is 20% or more for practical use. There is no problem with the above, and if it exceeds 30%, the characteristics are even more excellent.

FIG. 13 is a cross-sectional layout diagram for explaining the configuration and operation of the light source of this embodiment for polarization conversion in the light source device 13 including the light guide 203 and the LED element 201 described above. In FIG. 13, the light source device 13 includes, for example, a light guide 203 formed of plastic or the like and provided with a light beam direction changing means 204 on its surface or inside, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 206, It is composed of a lenticular lens or the like, and a liquid crystal display panel 11 having polarizing plates on the light source light entrance surface and the image light exit surface is attached to the upper surface thereof.

A film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (bottom surface in the drawing) of the liquid crystal display panel 11 corresponding to the light source device 13 . A polarized wave (for example, P wave) 212 on one side is selectively reflected, reflected by a reflective sheet 205 provided on one side (lower side in the drawing) of the light guide 203, and directed toward the liquid crystal display panel 11 again. to Therefore, a retardation plate (λ/4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49 so that the light is reflected by the reflective sheet 205 and passed through twice. converts the reflected luminous flux from P-polarized light to S-polarized light to improve the utilization efficiency of the light source light as image light.

The image light beam (arrow 213 in FIG. 13) whose light intensity is modulated by the image signal in the liquid crystal display panel 11 is incident on the retroreflective member 2, and as shown in FIG. A space floating image, which is a real image, can be obtained inside or outside the store (space).

FIG. 14 is a cross-sectional layout diagram for explaining the configuration and action of the light source of this embodiment for polarization conversion in the light source device 13 including the light guide 203 and the LED element 201, similar to FIG. Similarly, the light source device 13 also includes a light guide 203 formed of plastic or the like and provided with a light beam direction changing means 204 on its surface or inside, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 206, and a lenticular lens. etc. On the light guide 203, a liquid crystal display panel 11 is attached as an image display element, which has polarizing plates on the light source light entrance surface and the image light exit surface.

In addition, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (lower surface in the drawing) of the liquid crystal display panel 11 corresponding to the light source device 13 to polarize the natural light beam 210 emitted from the LED light source 201 to one side. A wave (for example, an S wave) 211 is selectively reflected, reflected by a reflective sheet 205 provided on one surface (lower side in the figure) of the light guide 203 , and directed toward the liquid crystal display panel 11 again. A retardation plate (λ/4 plate) is provided between the reflective sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49, and the light is reflected by the reflective sheet 205 and passed twice. The luminous flux is converted from S-polarized light to P-polarized light to improve the utilization efficiency of light source light as image light. The image light flux (arrow 214 in FIG. 14) whose light intensity is modulated by the image signal on the liquid crystal display panel 11 is incident on the retroreflection member 2, and as shown in FIG. A spatial floating image, which is a real image, can be obtained inside or outside (space).

In the light source device shown in FIGS. 13 and 14, in addition to the function of the polarizing plate provided on the light incident surface of the corresponding liquid crystal display panel 11, the reflective polarizing plate 49 reflects the polarized component on one side. The obtained contrast ratio is obtained by multiplying the reciprocal of the cross transmittance of the reflective polarizing plate by the reciprocal of the cross transmittance obtained by the two polarizing plates attached to the liquid crystal display panel. This provides high contrast performance. In practice, it was confirmed through experiments that the contrast performance of the displayed image is improved by ten times or more. As a result, a high-quality image comparable to that of a self-luminous organic EL was obtained.

<Example 2 of image display device>
FIG. 15 shows another example of a specific configuration of the image display device 1. As shown in FIG. The light source device 13 in FIG. 15 is the same as the light source device in FIG. 17 and the like. The light source device 13 is configured by housing an LED, a collimator, a synthetic diffusion block, a light guide, etc. in a case made of plastic, for example, and a liquid crystal display panel 11 is attached to the upper surface thereof. In addition, LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and an LED board on which the control circuit is mounted are attached to one side surface of the case of the light source device 13. , a heat sink 103, which is a member for cooling heat generated by the LED element and the control circuit (see also FIGS. 17, 18, etc.).

Further, the liquid crystal display panel frame attached to the upper surface of the case includes the liquid crystal display panel 11 attached to the frame and FPCs (Flexible Printed Circuits: flexible wiring boards) electrically connected to the liquid crystal display panel 11. ) 403 (see FIG. 7) and the like are attached. 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-state light sources, adjusts the intensity of transmitted light based on a control signal from a control circuit (not shown here) that constitutes the electronic device. to generate the displayed image.

<Example 1 of light source device for example 2 of image display device>
Next, 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. 17(a) and 18(b).

FIGS. 17 and 18 show LEDs 14a and 14b constituting the light source, which are attached to the collimator 15 at predetermined positions. Each of the collimators 15 is made of translucent resin such as acryl. 18(b), the collimator 15 has a conical outer peripheral surface 156 obtained by rotating the parabolic cross section, and the center of the top (the side in contact with the LED substrate). It has a concave portion 153 in which a convex portion (that is, convex lens surface) 157 is formed.

In addition, the central portion of the planar portion of the collimator 15 (the side opposite to the top portion) has an outwardly projecting convex lens surface (or an inwardly recessed concave lens surface) 154 . In addition, the paraboloid 156 forming the conical outer peripheral surface of the collimator 15 is set within an angle range capable of totally reflecting the light emitted from the LEDs 14a and 14b in the peripheral direction, or A reflective surface is formed.

Also, the LEDs 14a and 14b are arranged at predetermined positions on the surface of the LED board 102, which is the circuit board thereof. The LED substrate 102 is arranged and fixed to the collimator 15 so that the LEDs 14a or 14b on its surface are positioned in the central portion of the concave portion 153, respectively.

According to such a configuration, among the light emitted from the LED 14a or 14b by the collimator 15 described above, the light emitted upward (to the right in the drawing) from the central portion in particular, has the outer shape of the collimator 15. The light is condensed by two convex lens surfaces 157 and 154 to form 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 into parallel light. In other words, the collimator 15, which has a convex lens in its central portion and a parabolic surface in its peripheral portion, makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light. , it is possible to improve the utilization efficiency of the generated light.

A polarization conversion element 21 is provided on the light exit side of the collimator 15 . The polarization conversion element 21 may also be called a polarization conversion member. As is clear from FIG. 18, the polarization conversion element 21 includes a columnar translucent member having a parallelogram cross section (hereinafter referred to as a parallelogram prism) and a columnar light transmitting member having a triangular cross section (hereinafter referred to as a triangular prism). ), and arranged in an array parallel to a plane perpendicular to the optical axis of the parallel light from the collimator 15 . Furthermore, a polarizing beam splitter (hereinafter abbreviated as “PBS film”) 211 and a reflective film 212 are alternately provided at the interfaces between the adjacent translucent members arranged in an array. A λ/2 phase plate 213 is provided on the exit surface from which the light that has entered the polarization conversion element 21 and passed through the PBS film 211 is emitted.

A rectangular composite diffusion block 16 is further provided on the exit surface of the polarization conversion element 21, as shown in FIG. 18(a). That is, the light emitted from the LED 14a or 14b is collimated by the function of the collimator 15, enters the synthesizing diffusion block 16, and reaches the light guide 17 after being diffused by the texture 161 on the output side.

The light guide 17 is a rod-shaped member with a substantially triangular cross section (see FIG. 18B) made of translucent resin such as acrylic. A light guide light entrance portion (surface) 171 facing the exit 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 second diffusion A light guide light emitting portion (surface) 173 is provided so as to face the liquid crystal display panel 11, which is a liquid crystal display element, via the plate 18b.

As shown in FIG. 17, which is a partially enlarged view, on the light guide body light reflecting portion (surface) 172 of the light guide body 17, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. formed. Reflecting surface 172a (a line segment rising to the right in the drawing) forms αn (n: a natural number, for example, 1 to 130 in this example) with respect to the horizontal plane indicated by the dashed line in the drawing. As an example, here αn is set to 43 degrees or less (however, 0 degrees or more).

On the other hand, the light guide entrance 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.

According to the light source device 13 configured as described above, the parallel light emitted from the emission surface of the combined diffusion block 16 is diffused through the first diffusion plate 18a and diffused through the light guide entrance portion of the light guide 17. Incident on (plane) 171 . As is clear from FIG. 17, the light incident on the light guide 17 is slightly bent (deflected) upward when incident on the light guide incident portion (surface) 171 and passes through the light guide light reflecting portion ( 172, 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 exit surface in FIG.

According to the image 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, to manufacture the light source device including the modularized S-polarized wave light source device at a small size and at a low cost. It becomes possible. In the above description, the polarization conversion element 21 is attached after the collimator 15, but the present invention is not limited to this, and the same can be applied by providing it in the optical path leading to the liquid crystal display panel 11. Actions and effects can be obtained.

The light guide body light reflecting portion (surface) 172 has a large number of reflecting surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth shape. Further, the light guide body light emitting portion (surface) 173 is provided with a narrow-angle diffuser plate, and the diffused light flux is incident on the light direction conversion panel 54 for adjusting the directivity characteristics from an oblique direction. The light enters the liquid crystal display panel 11 . Although the light direction changing panel 54 is provided between the light guide exit surface 173 and the liquid crystal display panel 11 in this embodiment, the same effect can be obtained even if it is provided on the exit surface of the liquid crystal display panel 11 .

<Example 2 of light source device for example 2 of image display device>
Another example of the configuration of the optical system such as the light source device 13 is shown in FIG. Similarly to the example shown in FIG. 18, the optical system shown in FIG. installed in position. Each of the collimators 15 is made of translucent resin such as acryl. 18, the collimator 15 has a conical convex outer peripheral surface 156 obtained by rotating the parabolic cross section, and has a convex portion (that is, It has a concave portion 153 in which a convex lens surface 157 is formed. In addition, in the central portion of the plane portion, there is a convex lens surface (or a concave lens surface recessed inward) 154 that protrudes outward. In addition, the paraboloid 156 forming the conical outer peripheral surface of the collimator 15 is set within an angle range in which the light emitted in the peripheral direction from the LED 14a can be totally reflected therein, or the reflective surface is formed.

Also, the LEDs 14a and 14b are arranged at predetermined positions on the surface of the LED board 102, which is the circuit board thereof. The LED substrate 102 is arranged and fixed to the collimator 15 so that the LEDs 14a or 14b on its surface are positioned in the central portion of the concave portion 153, respectively.

According to such a configuration, among the light emitted from the LED 14a or 14b by the collimator 15 described above, the light emitted upward (to the right in the drawing) from the central portion in particular, has the outer shape of the collimator 15. The light is condensed by two convex lens surfaces 157 and 154 to form 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 into parallel light. In other words, the collimator 15, which has a convex lens in its central portion and a parabolic surface in its peripheral portion, makes it possible to extract almost all of the light generated by the LED 14a or 14b as parallel light. , it is possible to improve the utilization efficiency of the generated light.

A light guide 170 is provided on the light exit side of the collimator 15 via the first diffusion plate 18a. The light guide 170 is a rod-shaped member with a substantially triangular cross section (see FIG. 19A) made of translucent resin such as acrylic. 2, an incident portion (surface) 171 of the light guide body light 170 facing the emission surface of the diffusion block 16 via the first diffusion plate 18a, a light guide body light reflection portion (surface) 172 forming an inclined surface, It has a light guide light emitting portion (surface) 173 facing the liquid crystal display panel 11, which is a liquid crystal display element, with the reflective polarizing plate 200 interposed therebetween.

For this reflective polarizing plate 200, if a material having a characteristic of reflecting P-polarized light (transmitting S-polarized light) is selected, the P-polarized light of the natural light emitted from the LED as the light source will be reflected, resulting in FIG. 19(b). passes through the λ/4 plate 202 provided in the light guide light reflecting portion 172 shown in FIG. All the light beams incident on are unified into S-polarized light.

Similarly, if a reflective polarizing plate 200 having a characteristic of reflecting S-polarized light (transmitting P-polarized light) is selected, the S-polarized light of the natural light emitted from the LED, which is the light source, will be reflected, resulting in FIG. 19(b). The light passes through the λ/4 plate 202 provided in the light guide light reflecting portion 172 shown in FIG. All the light beams incident on are unified into P-polarized light. Polarization conversion can also be achieved with the configuration described above.

<Example 3 of video display device>
Next, another example of the specific configuration of the video display device 1 (example 3 of the video display device) will be described with reference to FIG. 16 . The light source device of this image display device 1 converts a divergent light beam (P-polarized light and S-polarized light mixed) from the LED into a substantially parallel light beam by the collimator 18, and the reflection surface of the reflective light guide 304 converts the light into a liquid crystal display panel. Reflect towards 11. The reflected light enters the reflective polarizing plate 49 arranged between the liquid crystal display panel 11 and the reflective light guide 304 .

A specific polarized wave (for example, P-polarized light) is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11 . The other polarized wave (for example, S-polarized light) is reflected by the reflective polarizing plate and directed to the reflective light guide 304 again. The reflective polarizing plate 49 is installed at an angle so as not to be perpendicular to the principal ray of light from the reflecting surface of the reflective light guide 304, and the principal ray of light reflected by the reflective polarizing plate 49 is , is incident on the transmission surface of the reflective light guide 304 .

The light incident on the transmissive surface of the reflective light guide 304 is transmitted through the back surface of the reflective light guide 304 , transmitted through the λ/4 plate 270 as a retardation plate, and reflected by the reflector 271 . The light reflected by the reflecting plate 271 passes through the λ/4 plate 270 again and passes through the transmitting surface of the reflective light guide 304 . Light transmitted through the transmissive surface of the reflective light guide 304 enters the reflective polarizing plate 49 again.

At this time, the light incident on the reflective polarizing plate 49 again passes through the λ/4 plate 270 twice, so that the polarization is converted into a polarized wave (for example, P-polarized light) that passes through the reflective polarizing plate 49. ing. Therefore, the light whose polarization has been converted passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11 . Regarding the polarization design related to polarization conversion, the polarization may be reversed (reversing the S-polarized light and the P-polarized light) from the above description.

As a result, the light from the LEDs is aligned with a specific polarized wave (for example, P-polarized light), is incident on the liquid crystal display panel 11, is luminance-modulated in accordance with the video signal, and displays an image on the panel surface. A plurality of LEDs constituting the light source are provided in the same manner as in the above example (however, only one LED is shown in FIG. 16 because it is a vertical section), and these are positioned at predetermined positions with respect to the collimator 18. installed.

The collimators 18 are made of translucent resin such as acrylic or glass. The collimator 18 may have a convex conical outer peripheral surface obtained by rotating the parabolic section. The top portion may have a concave portion with a convex portion (that is, a convex lens surface) formed in the central portion. In addition, the central portion of the planar portion has an outwardly projecting convex lens surface (or an inwardly recessed concave lens surface may be used). In addition, the paraboloid that forms the conical outer peripheral surface of the collimator 18 is set within an angle range that allows total internal reflection of the light emitted from the LED in the peripheral direction, or the reflecting surface is formed.

The LEDs are arranged at predetermined positions on the surface of the LED board 102, which is the circuit board. The LED substrate 102 is arranged and fixed to the collimator 18 so that the LEDs on the surface thereof are positioned at the central portion of the top of the conical convex shape (if the top has a concave portion, the concave portion). be.

According to such a configuration, of the light emitted from the LED by the collimator 18, particularly the light emitted from the central portion is condensed by the convex lens surface forming the outer shape of the collimator 18 and becomes parallel light. Also, the light emitted in the peripheral direction from other portions is reflected by the paraboloid forming the conical outer peripheral surface of the collimator 18, and is similarly condensed into parallel light. In other words, the collimator 18, which has a convex lens in its central portion and a parabolic surface in its peripheral portion, makes it possible to extract almost all of the light generated by the LED as parallel light. It is possible to improve the utilization efficiency of the light.

The above configuration is similar to that of the light source device of the image display device shown in FIGS. 17 and 18 and the like. Furthermore, the light converted into substantially parallel light by the collimator 18 shown in FIG. 16 is reflected by the reflective light guide 304 . Of the light, the light of a specific polarized wave is transmitted through the reflective polarizing plate 49 by the action of the reflective polarizing plate 49, and the light of the other polarized wave reflected by the action of the reflective polarizing plate 49 is guided again. It passes through the light body 304 . The light is reflected by the reflector 271 located opposite to the liquid crystal display panel 11 with respect to the reflective light guide 304 . At this time, the light is polarization-converted by passing through the λ/4 plate 270, which is a retardation plate, twice.

The light reflected by the reflecting plate 271 passes through the light guide 304 again and enters the reflective polarizing plate 49 provided on the opposite surface. Since the incident light has undergone polarization conversion, it is transmitted through the reflective polarizing plate 49 and made incident on the liquid crystal display panel 11 with the polarization direction aligned. As a result, all the light from the light source can be used, so that the geometrical optics utilization efficiency of light is doubled. In addition, since the degree of polarization (extinction ratio) of the reflective polarizing plate can be added to the extinction ratio of the entire system, the use of the light source device of this embodiment significantly improves the contrast ratio of the entire display device.

By adjusting the surface roughness of the reflecting surface of the reflective light guide 304 and the surface roughness of the reflecting plate 271, the reflection diffusion angle of light on each reflecting surface can be adjusted. The surface roughness of the reflective 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 is more favorable.

In the example described with reference to FIG. 16, the λ/4 plate 270, which is a retardation plate, has a phase difference of λ/4 with respect to the polarized light incident perpendicularly to the λ/4 plate 270. However, this is not necessarily the case. It doesn't have to be configured like this. In the configuration of FIG. 16, the λ/4 plate 270 may be a retardation plate that changes the phase by 90° (λ/2) when the polarized light passes through it twice. Also, the thickness of the retardation plate may be adjusted according to the incident angle distribution of polarized light.

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

Specifically, two optical sheets (an optical sheet 207A and an optical sheet 207B), the light from the collimator 18 is made incident between two optical sheets (diffusion sheets). This optical sheet may be composed of one sheet instead of two sheets. In the case of a one-sheet structure, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes of the front and back surfaces of one optical sheet.

Alternatively, a plurality of diffusion sheets may be used and each diffusion sheet may share the function of diffusion. Here, in the example of FIG. 25, the number of LEDs and The divergence angle from the LED substrate (optical element) 102 and the optical specifications of the collimator 18 should be used as design parameters for optimal design. That is, the diffusion characteristics are adjusted by the surface shape of a plurality of diffusion sheets instead of the light guide.

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

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 polarized light is transmitted through the reflective change plate 49 and enters the liquid crystal display panel 11 . It should be noted that the λ/4 plate 270, which is the retardation plate in FIG. In the configuration of FIG. 25, the λ/4 plate 270 may be a retardation plate that changes the phase by 90° (λ/2) when the polarized light passes through it twice. The thickness of the retardation plate may be adjusted according to the incident angle distribution of polarized light. In FIG. 25 as well, regarding the polarization design related to polarization conversion, the polarized waves may be reversed from the above description (S polarized light and P polarized light may be reversed).

Light emitted from the liquid crystal display panel 11 has, for example, "conventional characteristics (X direction)" in FIG. 22A and "conventional characteristics (Y direction)" in FIG. ”, the horizontal direction of the screen (the display direction corresponding to the X-axis of the graph of FIG. 22A) and the vertical direction of the screen (the display direction corresponding to the Y-axis of the graph of FIG. 22B) and have diffusion characteristics similar to each other.

On the other hand, the diffusion characteristics of the light flux emitted from the liquid crystal display panel of this embodiment are, for example, "Example 1 (X direction)" in FIG. 22A and "Example 1 (Y direction)" in FIG. The diffusion characteristics are as shown in the plot curve of “direction)”.

In one specific example, when the viewing angle is set to 13 degrees at which the brightness is 50% (the brightness is reduced to about half) with respect to the brightness when viewed from the front (angle of 0 degrees), the viewing angle is set to 13 degrees. The angle is about 1/5 of the diffusion characteristic of a device for TV use (angle of 62 degrees). Similarly, in an example of setting the viewing angle in the vertical direction unevenly between the upper side and the lower side, the viewing angle in the upper side is suppressed (narrowed) to about ⅓ of the viewing angle in the lower side. , the reflection angle of the reflective light guide, the area of the reflective surface, etc. are optimized.

By setting the viewing angle and the like as described above, compared to conventional liquid crystal TVs, the amount of light in the image directed toward the user's viewing direction is significantly increased (the brightness of the image is greatly improved), The luminance of such an image becomes 50 times or more.

Furthermore, when the viewing angle characteristics shown in "Example 2" in FIG. 22 are used, the viewing angle becomes 50% of the brightness of the image obtained when viewed from the front (angle of 0 degrees) (the brightness is reduced to about half). is set to be 5 degrees, the angle (narrow viewing angle) is about 1/12 of the diffusion characteristic (angle of 62 degrees) of a general home TV device. Similarly, in one example of setting the vertical viewing angle equally between the upper and lower sides, a reflective type display is used so as to suppress (narrow) the vertical viewing angle to about 1/12 of the conventional one. Optimize the reflection angle of the light guide and the area of the reflection surface.

By making such settings, compared to conventional liquid crystal TVs, the brightness (light amount) of the image in the viewing direction (the direction of the user's line of sight) is greatly improved, and the brightness of the image is 100 times or more. .

As described above, by narrowing the viewing angle, the amount of luminous flux in the viewing direction can be concentrated, thereby greatly improving the light utilization efficiency. As a result, even if a liquid crystal display panel for general TV applications is used, by adjusting the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in brightness with the same power consumption, and it is possible to display information for bright outdoors. A video display device compatible with a display system can be provided.

When using a large liquid crystal display panel, the light around the screen is directed inward so that it faces the viewer when the center of the screen faces the viewer, thereby improving the overall brightness of the screen. improves. FIG. 20 shows the long side and 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 image display device (screen ratio 16:10) are used as parameters. is the angle of convergence of

The diagrams shown on the upper side of FIG. 20 are based on the assumption that the screen of the liquid crystal display panel is set vertically (hereinafter also referred to as “vertically used”) to view images. In this case, the convergence angle may be set according to the short side of the liquid crystal display panel (see the direction of arrow V in FIG. 20 as appropriate). As a more specific example, as shown in the plot graph in FIG. 20, for example, when a 22″ panel is used vertically and the viewing distance is 0.8 m, the convergence angle is set to 10 degrees. Thus, image light from each corner (four corners) of the screen can be effectively projected or output toward the viewer.

Similarly, when a 15″ panel is viewed vertically, if the viewing distance is 0.8 m and the convergence angle is set to 7 degrees, the image light from the 4 corners of the screen can be effectively directed to the viewer. As described above, depending on the size of the liquid crystal display panel and whether it is used vertically or horizontally, the image light around the screen can be directed to the viewer at the optimal position for viewing the center of the screen. , the overall brightness of the screen can be improved.

As a basic configuration, as shown in FIG. 16 and the like, a light beam having narrow-angle directional characteristics is made incident on the liquid crystal display panel 11 by a light source device, and the brightness of the liquid crystal display panel 11 is modulated in accordance with a video signal, so that the screen of the liquid crystal display panel 11 is displayed. A spatially floating image obtained by reflecting the image information displayed above by the retroreflective member is displayed outdoors or indoors through the transparent member 100 .

A plurality of examples of other examples of the light source device will be described below. Any of these other examples of the light source device may be employed in place of the light source device of the example of the image display device described above.

<Another Example 1 of Light Source Device>
Another example of the light source device will be described with reference to FIGS. 26(a) and 26(b). FIG. 26A is a diagram in which part of the liquid crystal display panel 11 and the diffuser plate 206 is omitted in order to explain the light guide 311. FIG.

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

As shown in FIG. 26A, 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 which the reflector 300 is arranged. In the illustrated example, a reflector 300 is arranged corresponding to the arrangement of the LEDs. A plurality of reflectors 300 may be arranged.

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

As shown in FIG. 26(b), the inner surface (right side in the figure) of the reflector 300 is a reflective surface (hereinafter sometimes referred to as a “paraboloid”) having a shape obtained by cutting a parabola along the meridian. ) 305 . The reflector 300 converts the diverging light emitted from the LED 14 into substantially parallel light by reflecting it on the reflecting surface 305 (parabolic surface), and the converted light is incident on the end face of the light guide 311. Let In one embodiment, light guide 311 is a transmissive light guide.

The reflecting surface of the reflector 300 has an asymmetrical shape with respect to the optical axis of the light emitted from the LED 14 . In addition, the reflecting surface 305 of the reflector 300 is a paraboloid as described above, and by arranging the LED at the focal point of the paraboloid, the light flux after reflection is converted into substantially parallel light.

Since the LED 14 is a surface light source, even if it is arranged at the focal point of the paraboloid, the divergent light from the LED cannot be converted into perfectly parallel light, but this does not affect the performance of the light source of the present invention. The LED 14 and the reflector 300 are a pair, and in order to ensure the predetermined performance with the installation accuracy of ±40 μm of the LED 14 to the substrate 102, the number of LED substrates should be attached to a maximum of 10 or less, considering mass production. If so, it is better to keep it to about 5.

Although the LED 14 and the reflector 300 are partially close to each other, the heat can be dissipated to the space on the opening side of the reflector 300, so that the temperature rise of the LED can be reduced. Therefore, a plastic molded reflector 300 can be used. As a result, the shape accuracy of the reflecting surface can be improved by ten times or more compared to a reflector made of a glass material, so that the light utilization efficiency can be improved.

On the other hand, a reflective surface is provided on the bottom surface 303 of the light guide 311 , and the light from the LED 14 is converted into a parallel light flux by the reflector 300 , reflected by the reflective surface, and placed facing the light guide 311 . The light is emitted toward the liquid crystal display panel 11 . 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 flux 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 flux from the reflector 300 .

Further, the shape of the reflecting surface provided on the bottom surface 303 may be a planar shape. At this time, the light reflected by the reflecting surface 303 provided on the bottom surface 303 of the light guide 311 is refracted by the refracting surface 314 provided on the surface of the light guide 311 facing the liquid crystal display panel 11 . To adjust the light amount and the output direction of the light flux toward the target with high accuracy.

As shown in FIG. 26, the refracting surface 314 may have a plurality of surfaces with different inclinations in the direction in which the parallel light flux from the reflector 300 travels. 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 flux 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 . Also, the refracting surface 314 may be a transmissive surface.

Note that 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 by 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 are parallel to the extending directions of the plurality of surfaces with different inclinations of the reflective surface provided on the bottom surface 303 . The angle of light can be more preferably adjusted by making the stretching directions of both parallel. 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.

Further, the reflector 300 may be in contact with the substrate 102, but a space may be left between them. If the space is open, the reflector 300 is placed by being adhered to the housing. By keeping the space open, the heat generated by the LED can be dissipated into the air, increasing the cooling effect. As a result, the operating temperature of the LED can be reduced, so that the luminous efficiency can be maintained and the life of the LED can be extended.

<Another Example 2 of Light Source Device>
27A (1) (2) and FIG. 27B ( 1) (2) and FIGS. 27C and 27D (1) and (2). Note that the illustration of the sub-reflector 308 is omitted in FIG. 27A(1).

FIGS. 27A, 27B and 27C show the LEDs 14 constituting the light source mounted on the substrate 102. These are composed of the reflector 300 and the LEDs 14 as a pair of blocks, and a unit 312 having a plurality of blocks. .

Among them, the base material 320 shown in FIG. 27A(2) is the base material of the substrate 102 . In general, the substrate 102 made of metal has heat, so in order to insulate (insulate) the heat of the substrate 102, it is preferable to use a plastic material or the like for the base material 320. FIG. The material and the shape of the reflecting surface of the reflector 300 may be the same material and shape as the example of the light source device in FIG.

Moreover, the reflecting surface of the reflector 300 may have an asymmetrical shape with respect to the optical axis of the light emitted from the LED 14 . The reason for this will be explained with reference to FIG. 27A(2). In this embodiment, the reflection surface of the reflector 300 is a paraboloid, as in the example of FIG. 26, and the center of the light emitting surface of the LED, which is a surface light source, is placed at the focal position of the paraboloid.

In addition, due to the characteristics of the paraboloid, the light emitted from the four corners of the light emitting surface also becomes substantially parallel light beams, and the only difference is the direction of emission. Therefore, even if the light emitting part has a large area, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected if the distance between the polarization conversion element arranged in the rear stage and the reflector 300 is short.

Moreover, even if the mounting position of the LED 14 is deviated from the focal point of the corresponding reflector 300 within the XY plane, it is possible to realize an optical system that can reduce the decrease in the light conversion efficiency for the reason described above. Furthermore, even if the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light flux only moves within the ZX plane, and the mounting accuracy of the LED, which is a surface light source, can be greatly reduced. In the present embodiment, the reflector 300 having a reflecting surface obtained by cutting a part of the paraboloid in a meridian manner has been described, but the LED may be arranged on a part of the cutting that uses the entire paraboloid as a reflecting surface.

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 the polarization conversion element 21 in the latter stage A characteristic configuration is that the light is made incident on the end surface and aligned to a specific polarized wave by the polarization conversion element 21 . With this characteristic configuration, in the present invention, the light utilization efficiency is 1.8 times that of the example of FIG. 26 described above, and a highly efficient light source can be realized.

It should be noted that, at this time, not all of the substantially parallel light obtained by reflecting the divergent light from the LED 14 on the parabolic surface 321 is uniform. Therefore, by adjusting the angular distribution of the reflected light with the reflective surface 307 having a plurality of inclinations, the light can be incident on the liquid crystal display panel 11 in the vertical direction.

Here, in the example of this figure, the direction of the light (principal ray) entering the reflector from the LED and the direction of 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, since the temperature rise of the LED can be reduced by escaping air upward.

Further, as shown in FIG. 27B(1), in order to improve the capture rate of the divergent light from the LED 14, the luminous flux that cannot be captured by the reflector 300 is reflected by the sub-reflector 308 provided on the light shielding plate 309 arranged above the reflector. , the light is reflected by the slope of the lower sub-reflector 310 and is incident on the effective area of the polarization conversion element 21 in the latter stage, thereby further improving the light utilization efficiency. That is, in this embodiment, 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 toward the light guide 306 .

Thus, the substantially parallel light flux aligned to a specific polarized wave by the polarization conversion element 21 is arranged to face the exit surface of the reflective light guide 306 due to the reflection shape provided on the surface of the reflective light guide 306 . The light is reflected toward the liquid crystal display panel 11 . At this time, the light amount distribution of the light flux incident on the liquid crystal display panel 11 is determined by the shape and arrangement of the reflector 300 described above, the reflecting surface shape (cross-sectional shape) of the reflecting type light guide, the inclination of the reflecting surface, the surface roughness, and the like. Determined by prior setting or adjustment (optimal design). In other words, by optimizing the above-described settings or adjustment items, the light quantity distribution of the light flux incident on the liquid crystal display panel 11 is optimized.

As for the shape of the reflective surface provided on the surface of the light guide 306, a plurality of reflective surfaces are arranged so as to face the exit surface of the polarization conversion element, and the inclination, area, and By optimizing the height and pitch, the light amount distribution of the light flux incident on the liquid crystal display panel 11 can be set to a desired value as described above.

As shown in FIG. 27B(2), the reflective surface 307 provided on the reflective light guide is configured to have a plurality of inclinations on one surface, so that reflected light can be adjusted with higher accuracy. . In addition, in the reflective surface, as a configuration in which one surface has a plurality of inclinations, the area used as the reflective surface may be a plurality of surfaces, a multi-surface, or a curved surface. Further, the diffusion action of the diffuser plate 206 realizes a more uniform light quantity distribution. The light incident on the diffusion plate on the side closer to the LEDs achieves a uniform light amount distribution by changing the inclination of the reflection surface.

In this embodiment, a plastic material such as heat-resistant polycarbonate is used as the base material of the reflecting surface 307 . Further, the angle of the reflecting surface 307 immediately after the λ/2 plate 213 is emitted changes depending on the distance between the λ/2 plate and the reflecting surface.

Also in this embodiment, the LED 14 and the reflector 300 are partially close to each other, but the 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. Also, the substrate 102 and the reflector 300 may be arranged upside down as shown in FIGS. 27A, 27B, and 27C.

However, if the substrate 102 is placed on top, the substrate 102 will be closer to the liquid crystal display panel 11, which may make the layout difficult. Therefore, as shown in the figure, arranging the substrate 102 on the lower side of the reflector 300 (the side farther from the liquid crystal display panel 11) simplifies the internal configuration of the device.

A light shielding plate 410 may be provided on the light incident surface of the polarization conversion element 21 so as to prevent unnecessary light from entering the subsequent optical system. With such a configuration, a light source device that suppresses temperature rise can be realized. The polarizing plate provided on the light incident surface of the liquid crystal display panel 11 can reduce the temperature rise by absorbing the luminous flux with uniform polarization. is absorbed by the incident-side polarizing plate. Furthermore, the temperature of the liquid crystal display panel 11 also rises due to the temperature rise due to the absorption by the liquid crystal itself and the light incident on the electrode pattern. Therefore, the temperature rise of the liquid crystal display panel 11 can be suppressed by natural cooling using such a space.

FIG. 27D is a modification of the light source device of FIGS. 27B(1) and 27C. FIG. 27D(1) shows a modification of part of the light source device of FIG. 27B(1). Since other configurations are the same as those of the light source device described above with reference to FIG. 27B(1), illustrations and repeated descriptions are omitted.

First, in the example shown in FIG. 27D(1), the height of the concave portion 319 of the sub-reflector 310 is set so that the principal ray of fluorescence emitted from the phosphor 114 in the lateral direction (X-axis direction) (X (see the straight line extending in the direction parallel to the axis) is adjusted to be lower than the phosphor 114 so as to escape from the concave portion 319 of the sub-reflector 310 . Further, the position of the phosphor 114 is adjusted in the Z-axis direction so that the principal ray of the fluorescence emitted sideways from the phosphor 114 is not blocked by the light shielding plate 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 low.

Moreover, the reflecting surface of the uneven convex portion 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 made incident on the effective area of the polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency. can be improved.

Incidentally, the sub-reflector 310 is arranged extending in one direction as shown in FIG. 27A(2), and has an uneven shape. Further, on the top of the sub-reflector 310, irregularities having one or more concave portions are periodically arranged along one direction. By forming such an uneven shape, the principal ray of fluorescence emitted from the phosphor 114 in the horizontal direction can be made incident on the effective region of the polarization conversion element 21 .

Further, the uneven shape of the sub-reflector 310 is periodically arranged at a pitch such that the concave portion 319 is positioned at the position where the LED 14 is located. That is, each of the phosphors 114 is periodically arranged along one direction corresponding to the arrangement pitch of the concavities and convexities of the sub-reflector 310 . When the LED 14 is provided with the phosphor 114, the phosphor 114 may be expressed as the light emitting portion of the light source.

Also, FIG. 27D(2) shows a modification of part of the light source device of FIG. 27C. Since other configurations are the same as those of the light source device of FIG. 27C, illustrations and repeated descriptions are omitted. As shown in FIG. 27D(2), the sub-reflector 310 may be omitted, but as in FIG. The light shielding plate 410 is adjusted to be lower in the Z-axis direction with respect to the position of the phosphor 114 so that the light is incident on the effective region of the polarization conversion element 21 .

27A, 27B, 27C, and 27D, as shown in 27A(1), dust enters the space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11. A side wall 400 may be provided to prevent stray light from occurring outside the light source device and prevent stray light from entering from the outside of the light source device. 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 .

The light exit 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 . In addition, of the inner surface of the side wall 400, the portion that covers from the side the space where light is output from the exit surface of the polarization conversion element 21 (the space on the right side of the exit surface of the polarization conversion element 21 in FIG. 27B(1)). A reflective surface having a reflective film or the like is used as the surface. That is, the surface of the sidewall 400 facing the space comprises a reflective area with a reflective film. By making the portion of the inner surface of the side wall 400 a reflective surface, the light reflected by the reflective surface can be reused as light source light, and the brightness of the light source device can be improved.

Of the inner surfaces of the side walls 400, the surfaces that cover the polarization conversion element 21 from the sides are surfaces with low light reflectance (such as black surfaces without a reflective film). This is because, if light is reflected on the side surface of the polarization conversion element 21, light with an unexpected polarization state is generated, which causes stray light. In other words, by making the above surface a surface with a low light reflectance, it is possible to prevent or suppress the generation of stray light from an image and light with an unexpected polarization state. Further, the cooling effect may be improved by providing a hole through which air passes through part of the side wall 400 .

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

<Another example 3 of the light source device>
28A (1), (2), (3) and FIG. 28A (1), (2), (3), and FIG. 28B for a detailed description.

FIG. 28A shows a state in which the LEDs 14 constituting the light source are mounted on the substrate 102, and these are configured by a unit 328 having a plurality of blocks, with the collimator 18 and the LEDs 14 forming 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. In addition, by providing a light shielding plate 317 in front of the polarization conversion element 21, unnecessary light is prevented or suppressed from entering the optical system in the subsequent stage, and temperature rise due to the unnecessary light is reduced. .

Other configurations and effects of the light source shown in FIG. 28A are the same as those in FIGS. 27A, 27B, 27C, and 27D, and thus repeated descriptions are omitted. The light source device of FIG. 28A may be provided with sidewalls in the same manner as described in FIGS. 27A, 27B, and 27C. Since the configuration and effects of the side walls have already been explained, repeated explanations will be omitted.

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

<Another Example 4 of Light Source Device>
Next, the light source device of FIG. 29 is configured by a unit 328 having a plurality of blocks as a pair of blocks, each of which includes the collimator 18 and the LED 14 used in the light source device shown in FIG. The configuration of the optical system relating to the light source device using the LEDs and the reflective light guides 504 arranged at both ends of the back surface of the liquid crystal display panel 11 will be described in detail with reference to FIGS. explain.

FIG. 29 shows a state in which the LEDs 14 constituting the light source are mounted on a substrate 505, which is composed of a unit 503 having a plurality of blocks in which the collimator 18 and the LEDs 14 are paired. The units 503 are arranged at both ends of the rear surface of the liquid crystal display panel 11 (in this embodiment, three units are arranged side by side in the short side direction). The light output from the unit 503 is reflected by the reflective light guide 504 and is incident on the liquid crystal display panel 11 (shown in FIG. 29(c)) arranged opposite to it.

As shown in FIG. 29(c), the reflective light guide 504 is divided into two blocks corresponding to the units arranged at the respective ends, and arranged so that the central portion is the highest. Since the collimator 18 is close to the LED 14, a glass material is used in consideration of heat resistance to the heat emitted from the LED 14. The shape of the collimator 18 is the shape described for the collimator 15 in FIG.

Light emitted from the LED 14 enters the polarization conversion element 501 via the collimator 18 . In this example, the shape of the optical element 81 is used to adjust the distribution of light incident on the reflective light guide 504 in the latter stage. That is, the light amount distribution of the light flux incident on the liquid crystal display panel 11 is determined by the shape of the collimator 18 described above, the arrangement and shape of the optical element 81, the diffusion characteristics, and the reflecting surface shape (cross-sectional shape) of the reflective light guide, The optimum design is achieved by adjusting the inclination of the reflecting surface and the surface roughness of the reflecting surface.

As for the shape of the reflective surface provided on the surface of the reflective light guide 504, as shown in FIG. Optimize the inclination, area, height, and pitch of the reflective surface according to the distance. In addition, by dividing the area serving as the same reflecting surface (that is, the surface facing the polarization conversion element) into polyhedrons, the light amount distribution of the light flux incident on the liquid crystal display panel 11 can be set to a desired value (optimal value) as described above. can be changed).

The reflective surface provided on the reflective light guide has a configuration in which one surface (area where light is reflected) has a shape with a plurality of inclinations, as in the reflective light guide described with reference to FIG. 27B. In the example of 29, the XY plane is divided into 14 and different inclined planes are formed), so that the reflected light can be adjusted with higher accuracy. In addition, in order to prevent the reflected light from the reflective light guide from leaking from the side surface of the light source device 13, a light shielding wall 507 is provided to prevent light from leaking in directions other than the desired direction (the direction toward the liquid crystal display panel 11). can be prevented from occurring.

29 may be replaced with the light source device of FIG. That is, a plurality of light source devices (substrate 102, reflector 300, LED 14, etc.) shown in FIG. It is good also as a structure arrange|positioned in the position which opposes.

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

Among the light emitted from the polarization conversion element 21 , the divergent light flux is totally reflected by the inclined surface of the protrusion provided on the incident surface of the diffuser plate 206 and enters the liquid crystal display panel 11 . In order to cause the light emitted from the polarization conversion element 21 to be totally reflected by the slopes of the projections of the diffusion plate 206 , the angles of the slopes of the projections are changed based on the distance from the polarization conversion element 21 . If the angle of the slope 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 slope of the protrusion on the side closer to the polarization conversion element 21 or the LED is α', then α is smaller than α' (α<α'). With such a setting, it is possible to effectively use the light flux that has undergone polarization conversion.

<Lenticular lens>
As a method of adjusting the diffusion distribution of image light from the liquid crystal display panel 11, a lenticular lens is provided between the light source device 13 and the liquid crystal display panel 11 or on the surface of the liquid crystal display panel 11, and the shape of the lens is optimized. It is mentioned that it becomes. That is, by optimizing the shape of the lenticular lens, it is possible to adjust the emission characteristics of the image light emitted in one direction from the liquid crystal display panel 11 (hereinafter also referred to as "image light flux").

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 mode of arrangement may be adjusted. That is, by adjusting the arrangement of the microlens array, it is possible to adjust the emission characteristics in the X-axis and Y-axis directions of the image light flux emitted from the image display device 1. As a result, desired diffusion characteristics can be obtained. can be obtained.

The action of the lenticular lens will be explained. As described above, when a lenticular lens with an optimized lens shape is used, the following effects are obtained. In other words, the emission characteristics of the image light flux emitted from the image display device 1 are adjusted (optimized) through the lenticular lens, and the optimized image light flux is efficiently transmitted or reflected by the window glass 105 to obtain a suitable A spatially floating image can be obtained.

As a further configuration example, at a position through which the image light emitted from the image display device 1 passes, two lenticular lenses are arranged in combination, or a sheet for adjusting diffusion characteristics by arranging a microlens array in a matrix. may be provided. With such an optical system configuration, in the X-axis and Y-axis directions, the luminance (relative luminance) of the image light can be calculated using the angle of reflection of the image light (reflected in the vertical direction as the reference (0 degrees) angle of reflection).

In this embodiment, by using such a lenticular lens, as shown in the graphs (plotted curves) of "Example 1 (Y direction)" and "Example 2 (Y direction)" in FIG. , excellent optical characteristics that are clearly different from the graph (plot curve) of conventional characteristics can be obtained. Specifically, in the plotted curves of Example 1 (Y direction) and Example 2 (Y direction), the luminance characteristics in the vertical direction are steepened, and the balance of the directional characteristics in the vertical direction (positive and negative directions of the Y axis) is changed. By doing so, it is possible to increase the luminance (relative luminance) of light due to reflection and diffusion.

For this reason, according to the present embodiment, like the image light from the surface emitting laser image source, the image light has a narrow diffusion angle (high straightness) and has only a specific polarized wave component, and the image display device according to the prior art is used. It is possible to suppress the ghost image generated in the retroreflective member when using .

In addition, with the light source device described above, the diffusion characteristics of emitted light from a general liquid crystal display panel shown in FIGS. It is possible to provide directivity characteristics with a significantly narrow angle in both the direction and the Y-axis direction. In the present embodiment, by providing such a narrow-angle directional characteristic, it is possible to realize an image display device that emits a nearly parallel image light flux in a specific direction and that emits light of a specific polarized wave. .

FIG. 21 shows an example of the characteristics of the lenticular lens employed in this embodiment. This example particularly shows the characteristics in the X direction (vertical direction) with respect to the Z axis. , and exhibits vertically symmetrical luminance characteristics. Further, the plot curves of characteristic A and characteristic B shown in the graph of FIG. 21 further show examples of characteristics in which the luminance (relative luminance) is increased by condensing the image light above the peak luminance near 30 degrees. there is Therefore, in these characteristics A and B, as can be seen by comparing with the plot curve of characteristic O, the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ>30°). In the region of , the brightness of light (relative brightness) is abruptly reduced.

That is, according to the optical system including the lenticular lens described above, when the image light flux from the image display device 1 is made incident on the retroreflection member 2, the emission angle and field of view of the image light aligned at a narrow angle by the light source device 13 are adjusted. The angle can be adjusted, and the degree of freedom in installing the retroreflective sheet 2 can be greatly improved. As a result, it is possible to greatly improve the degree of freedom in relation to the imaging position of the spatially floating image that is reflected or transmitted through the window glass 105 and focused at a desired position. As a result, it is possible to efficiently reach the eyes of a viewer indoors or outdoors as light with a narrow diffusion angle (high rectilinearity) and with only a specific polarized wave component. Accordingly, even if the intensity (brightness) of the image light from the image display device 1 is reduced, the viewer can accurately recognize the image light and obtain information. In other words, by reducing the output of the image display device 1, it is possible to realize an information display system with low power consumption.

Various embodiments and examples (that is, 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), and includes various modifications. For example, the above-described embodiments describe the entire system in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

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

In the technology according to the present embodiment, by displaying high-resolution and high-brightness video information in a floating state in space, the user can operate without feeling anxious about contact infection of an infectious disease, for example. enable If the technology according to this embodiment is applied to a system used by an unspecified number of users, it will be possible to reduce the risk of contact infection of infectious diseases and provide a non-contact user interface that can be used without anxiety. . According to the present invention, which provides such technology, it contributes to "3 Good Health and Welfare for All" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

Further, in the technique according to the above-described embodiment, by reducing the angle of divergence of the emitted image light and aligning it to a specific polarized wave, only regular reflected light can be efficiently reflected by the retroreflective member. , the use efficiency of light is high, and it is possible to obtain a bright and clear spatial floating image. According to the technology according to the present embodiment, it is possible to provide a highly usable non-contact user interface capable of significantly reducing power consumption. According to the present invention that provides such technology, the Sustainable Development Goals (SDGs: Sustainable Development Goals) advocated by the United Nations, "Let's build a foundation for 9 industries and technological innovation" and "11 Urban development that can continue to live" contribute to

Furthermore, the technique according to the above-described embodiment makes it possible to form a spatially floating image by image light with high directivity (straightness). With the technology according to the present embodiment, even when displaying images that require high security such as bank ATMs or ticket vending machines at stations, or highly confidential images that should be kept secret from the person facing the user, the directivity is high. By displaying image light, it is possible to provide a non-contact user interface that reduces the risk of someone other than the user looking into the floating image. By providing the above technology, the present invention contributes to "11 sustainable urban development" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

DESCRIPTION OF SYMBOLS 1... Video display apparatus 2... Retroreflection member 3... Spatial image (space floating image) 105... Window glass 100... Transmissive plate 101... Polarization separation member 12... Absorptive polarizing plate 13... Light source device , 54... Light direction conversion panel 151... Retroreflection member 102, 202... LED substrate 203... Light guide 205... Reflection sheet 271... Reflection plate 206, 270... Retardation plate 300... Spatial floating image , 301... Ghost image of space floating image 302... Ghost image of space floating image 11... Liquid crystal display panel 206... Diffusion plate 21... Polarization conversion element 300... LED reflector 213... λ/2 plate, reflective type Light guide 306, reflecting surface 307, sub-reflector 308, 310, 81 optical element, polarization conversion element 501, unit 503, light shielding wall 507, 401, 402 light shielding plate, 320 base material

Claims (18)

A spatial floating image display device,
a display panel for displaying images;
a light source device;
a retroreflection plate that reflects image light from the display panel and displays a floating image of a real image in the air by the reflected light;
The light source device
a point-like or planar light source;
a reflector that reflects light from the light source;
a light guide that guides light from the reflector toward the display panel;
The reflector has a reflecting surface shaped to form a pair with the light source,
the reflecting surface of the reflector has an asymmetrical shape with respect to the optical axis of the light emitted from the light source;
A plurality of the light sources are arranged side by side in the light source device, and a plurality of the reflecting surfaces paired with the plurality of the light sources arranged side by side are formed on the reflector. There is a space on the opening side of the reflecting surface, and the space can dissipate the heat of the light source into the air,
The light source device includes a light blocking plate arranged between the reflector and the light guide,
The light source is provided with a phosphor,
The light shielding plate is arranged so that a light flux traveling from the reflector to the light guide passes through a region surrounded by the light shielding plate,
The phosphor and the light shielding plate are arranged so that the light emitted perpendicularly from the side surface of the phosphor on the light guide side passes through the area surrounded by the light shielding plate without passing through the reflector. placed,
Spatial floating image display device. In the spatial floating image display device according to claim 1 ,
The light source device includes a polarization conversion element between the light shielding plate and the light guide,
The light shielding plate is provided on a surface of the polarization conversion element facing the reflector,
Spatial floating image display device. In the spatial floating image display device according to claim 2 ,
The reflecting surface of the reflector is configured to reflect the light from the light source so that the reflected light becomes substantially parallel light and travels toward the light guide,
A traveling direction of substantially parallel light from the reflector toward the light guide is defined as a first direction,
a plurality of the light sources, wherein the plurality of light sources are arranged in a row in a second direction;
In a third direction perpendicular to the first direction and the second direction, the light shielding plate extends longer than the edge of the polarization conversion element.
Spatial floating image display device. In the spatial floating image display device according to claim 1 or claim 2 ,
a plurality of said light sources;
The light sources are arranged in a row in a direction parallel to a side of the display panel on the reflector side among a plurality of sides of the display panel.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 1 to 4 ,
a diffusion plate that diffuses light from the light guide;
a side wall arranged to sandwich the space between the light guide and the diffusion plate;
Spatial floating image display device. In the spatial floating image display device according to any one of claims 1 to 5 ,
wherein the display panel is arranged to face the exit surface of the light guide;
Spatial floating image display device. In the spatial floating image display device according to claim 1 ,
A space is provided between the reflective surface of the light guide and the display panel, and natural cooling is performed in the space.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 1 to 7 ,
The reflector uses a plastic material, a glass material, or a metal material,
Spatial floating image display device. A spatial floating image display device,
a display panel for displaying images;
a light source device;
a retroreflection plate that reflects image light from the display panel and displays a floating image of a real image in the air by the reflected light;
The light source device
a point-like or planar light source;
a reflector that reflects light from the light source;
a light guide that guides light from the reflector toward the display panel;
the reflecting surface of the reflector has an asymmetrical shape with respect to the optical axis of the light emitted from the light source;
The light source device further comprises a light blocking plate arranged between the reflector and the light guide,
The light source is provided with a phosphor,
The light shielding plate is arranged so that a light flux traveling from the reflector to the light guide passes through a region surrounded by the light shielding plate,
The phosphor and the light shielding plate are arranged so that the light emitted perpendicularly from the side surface of the phosphor on the light guide side passes through the area surrounded by the light shielding plate without passing through the reflector. placed,
Spatial floating image display device. In the spatial floating image display device according to claim 9 ,
The light guide is a reflective light guide that guides light by reflection on a reflective surface on the surface of the light guide,
Spatial floating image display device. In the spatial floating image display device according to claim 9 or 10 ,
the reflective surface of the reflector is a paraboloid;
The reflector and the light guide are arranged so that the direction of the optical axis entering the reflector from the light source and the direction of light entering the display panel from the light guide are substantially parallel.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 9 to 11 ,
The light source device includes a polarization conversion element between the light shielding plate and the light guide,
The light shielding plate is provided on a surface of the polarization conversion element facing the reflector,
Spatial floating image display device. In the spatial floating image display device according to claim 12 ,
The reflecting surface of the reflector is configured to reflect the light from the light source so that the reflected light becomes substantially parallel light and travels toward the light guide,
A traveling direction of substantially parallel light from the reflector toward the light guide is defined as a first direction,
a plurality of the light sources, wherein the plurality of light sources are arranged in a row in a second direction;
In a third direction perpendicular to the first direction and the second direction, the light shielding plate extends longer than the edge of the polarization conversion element.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 9 to 13 ,
a plurality of said light sources;
The light sources are arranged in a row in a direction parallel to a side of the display panel on the reflector side among a plurality of sides of the display panel.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 9 to 14 ,
a diffusion plate that diffuses light from the light guide;
a side wall arranged to sandwich the space between the light guide and the diffusion plate;
Spatial floating image display device. In the spatial floating image display device according to any one of claims 9 to 15 ,
wherein the display panel is arranged to face the exit surface of the light guide;
Spatial floating image display device. In the spatial floating image display device according to claim 10 ,
A space is provided between the reflective surface of the reflective light guide and the display panel, and natural cooling is performed in the space.
Spatial floating image display device. In the spatial floating image display device according to any one of claims 9 to 17 ,
The reflector uses a plastic material, a glass material, or a metal material,
Spatial floating image display device.

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