JP7370433B2 - Light source device used in spatial floating video information display system - Google Patents

Description

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

As spatial floating information display systems, a video display device that directly displays video to the outside and a display method that displays video as a spatial screen are already known. Further, a detection system that reduces false detections caused by operations on the operation surface of the displayed spatial image is also disclosed in Patent Document 1, for example.

JP2019-128722A

However, as a method for reducing false detections caused by the above-mentioned conventional spatial floating video information display system and spatial image manipulation, optimization techniques for the design of the video display device, which is the image source of the spatial floating video, including the light source, have been considered. It has not been.

An object of the present invention is to provide a suitable image that has high visibility (visual resolution and contrast) and reduces false positives caused by manipulation of the displayed spatial image in a spatial floating information display system or a spatial floating video display device. The purpose is to provide technology that enables display.

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-mentioned problems, and a spatial floating video display device as an example thereof will be listed below. A spatially floating image display device as an example of the present application includes a display panel for displaying an image, a light source device, and a reflex function that reflects image light from the display panel and displays a real spatially floating image in the air using the reflected light. A reflector plate is provided. 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 a display panel. , a light shielding plate is provided between the reflector and the light guide, and the light shielding plate is arranged so that the light beam traveling from the reflector to the light guide passes through a region surrounded by the light shielding plate.

According to the present invention, it is possible to realize a space floating information display system or a space floating video display device that can suitably display space floating video information and has a sensing function with fewer false detections. Problems, configurations, and effects other than those described above will be made clear by the description of the embodiments below.

1 is a diagram illustrating an example of a usage pattern of a floating video information display system according to an embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an example of a configuration of main parts and a configuration of a retroreflection part of a floating video information display system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating another example of the configuration of the main parts of the floating video information display system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating another example of the configuration of the main parts of the floating video information display system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining the functions of a sensing device used in a floating video information display system. FIG. 2 is an explanatory diagram of the principle of three-dimensional video display used in the spatial floating video information display system. FIG. 2 is an explanatory diagram of a measurement system for evaluating the characteristics of a reflective polarizing plate. FIG. 3 is a characteristic diagram showing the transmittance characteristics of the transmission axis of a reflective polarizing plate with respect to the angle of incidence of light rays. FIG. 3 is a characteristic diagram showing the transmittance characteristics of the reflection axis of a reflective polarizing plate with respect to the angle of incidence of a light beam. FIG. 3 is a characteristic diagram showing the transmittance characteristics of the transmission axis of a reflective polarizing plate with respect to the angle of incidence of light rays. FIG. 3 is a characteristic diagram showing the transmittance characteristics of the reflection axis of a reflective polarizing plate with respect to the angle of incidence of a light beam. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. 1 is a layout diagram showing the main parts of a floating video information display system according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing the configuration of a video display device that constitutes a floating video information display system according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. FIG. 2 is a cross-sectional view showing an example of a specific configuration of a light source device. FIG. 3 is an explanatory diagram for explaining light source diffusion characteristics of a video display device. FIG. 3 is an explanatory diagram for explaining the diffusion characteristics of the video display device. FIG. 3 is an explanatory diagram for explaining the diffusion characteristics of the video display device. 1 is a cross-sectional view showing the configuration of a video display device that constitutes a floating video information display system. FIG. 2 is an explanatory diagram for explaining the principle of generation of ghost images in a spatially floating image information display system according to the prior art. 1 is a cross-sectional view showing the configuration of a video display device that constitutes a floating video information display system according to an embodiment of the present invention. It is a figure which shows another example of the specific structure of a light source device. It is a figure which shows another example of the specific structure of a light source device. FIG. 7 is a cross-sectional view showing another example of a specific configuration of the light source device. FIG. 7 is a cross-sectional view showing another example of a specific configuration of the light source device. FIG. 7 is a diagram illustrating a part of another example of a specific configuration of a light source device. It is a figure which shows another example of the specific structure of a light source device. FIG. 7 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 specific structure of a light source device. FIG. 7 is a cross-sectional view of an example of the shape of a diffuser plate in another example of a specific configuration of a light source device.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the content of the embodiments (hereinafter also referred to as "this disclosure") described below. The present invention extends to the spirit of the invention and the scope of the technical ideas described in the claims, or to equivalents thereof. Further, the configuration of the embodiment (example) described below is merely an example, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification. be.

In addition, in the drawings for explaining the present invention, parts having the same or similar functions are given the same reference numerals, different names are used as appropriate, and repeated explanations of functions, etc. are omitted. There is. In the following description of the embodiment, an image floating in space is expressed using the term "space floating image." Instead of this terminology, expressions such as "aerial image", "aerial image", "aerial floating image", "aerial floating optical image of a display image", "aerial floating optical image of a display 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.

The present disclosure, for example, transmits an image of image light from a large-area image light source through a transparent member that partitions a space, such as glass in a show window, and floats the image inside or outside of a store (space). The present invention relates to an information display system that can display 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 embodiments described below, it is possible to display high-resolution video information floating in space, for example, on the glass surface of a show window or on a light-transmitting board. At this time, by making the divergence angle of the emitted image light small, that is, an acute angle, and aligning it with a specific polarization, it is possible to efficiently reflect only the regular reflected light to the retroreflection member. Therefore, the light utilization efficiency is high, and ghost images generated in addition to the main space floating image, which were a problem with conventional retroreflection methods, can be suppressed, and a clear space floating image can be obtained.

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

On the other hand, in a conventional space floating video information display system, an organic EL panel or a liquid crystal display panel (liquid crystal panel or display panel) is combined with a retroreflective member 151 as a high resolution color display video source 150. In the conventional spatial floating image display device, since the image light is diffused at a wide angle, in addition to the reflected light normally reflected by the retroreflective member 151 (see FIG. 23), as shown in FIG. Ghost images (see reference numerals 301 and 302 in FIG. 23) are generated by the image light incident obliquely on 2a, impairing the image quality of the spatially floating image. Furthermore, 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, etc. are generated. For this reason, the ghost image floating in the same space could be viewed by people other than the viewer, which also posed a major problem from a security perspective.

<First configuration example of spatial floating video information display system>
FIG. 1(A) is a diagram illustrating an example of a usage pattern of the spatially floating video information display system of the present disclosure. Further, FIG. 1(A) is a diagram illustrating the overall configuration of a floating video information display system in 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 the floating image through such a transparent member and display the floating image in one direction to the outside of the store (space). It is possible.

Specifically, according to this system, light with a narrow directional characteristic and a specific polarization is emitted from the video display device (display device) 1 as a video light flux, once enters the retroreflective member 2, and is then reflected The light is reflected and transmitted through the window glass 105, forming a real aerial image 3 (space floating image 3) outside the store. In FIG. 1A, the inside of the transparent member (window glass in this case) 105 (inside the store) is shown as the depth direction, and the outside of the window glass 105 (for example, the sidewalk) is shown as the front.

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

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

Among these, the video signal receiving section supports wired input signals through input interlacing such as HDMI (High-Definition Multimedia Interface (registered trademark)) and Wi-Fi (registered trademark) (Wireless Fidelity). It plays the role of responding to wireless input signals such as Further, the video signal receiving section can also function independently as a video receiving/displaying device. Furthermore, the video signal receiving section can also display video information from a tablet, smartphone, etc. Furthermore, the video signal receiving section can also be connected to a processor (arithmetic processing unit) such as a stick PC as needed. In this case, the video signal receiving section as a whole has the ability to perform calculation processing, video analysis processing, etc. You can also have it.

FIG. 2 is a diagram illustrating an example of the configuration of main parts and the configuration of a retroreflection part of the spatially floating video information display system of the present disclosure. The configuration of the spatial floating video information display system will be explained in more detail using FIG. 2. As shown in FIG. 2(A), image light of a specific polarization is diverged at an angle in the diagonal direction of a transparent plate (hereinafter referred to as a "transparent member") 100 such as glass. A video display device 1 is provided. The video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics.

Image light of a specific polarization from the image display device 1 is transmitted to a polarization separation member 101 (in the figure, the polarization separation member 101 is a sheet) having a film that selectively reflects the image light of a specific polarization provided on a transparent member 100. (formed in a shape and adhered to the transparent member 100) and 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, once when it enters the retroreflective member and once when it exits, thereby converting the polarization from a specific polarization to the other polarization.

Here, the polarization separation member 101 that selectively reflects the image light of a specific polarization has a property of transmitting the polarized light of the other polarization that has been polarized, so the image light of the specific polarization after polarization conversion is , is transmitted through the polarization separation member 101. The image light transmitted through the polarization separation member 101 forms a spatial floating image 3 as a real image outside the transparent member 100.

Note that the light forming the floating image 3 is a collection of light rays that converge from the retroreflective member 2 to the optical image of the floating image 3, and these rays continue to travel straight even after passing through the optical image of the floating image 3. do. Therefore, the floating image 3 is a highly directional image, unlike the diffused image light formed on a screen by a general projector or the like.

Therefore, in the configuration of FIG. 2, when the user views the floating image 3 from the direction of arrow A, the floating image 3 is viewed as a bright image, but when another person views it from the direction of arrow B, the floating image 3 appears as a bright image. Video 3 cannot be viewed as a video at all. This characteristic is very suitable for use in a system that displays images that require high security or highly confidential images that should be kept secret from the person directly facing the user.

Note that depending on the performance of the retroreflection member 2, the polarization axes of the reflected image light may become uneven. In this case, some 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 . This part of the image light is re-reflected on the image display surface of the liquid crystal display panel 11 constituting the image display device 1 and generates a ghost image, which can be a factor that causes a deterioration in the image quality of the spatially floating image.

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

The polarized light 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 a retroreflective member manufactured by Nippon Carbide Industries Co., Ltd. used in this study as a representative retroreflective member 2. The light rays incident on the inside of the regularly arranged hexagonal prisms are reflected by the walls and bottoms of the hexagonal prisms and emitted as retroreflected light in the direction corresponding to the incident light, and a real image is generated based on the image displayed on the image display device 1. Displays a floating image in space. The resolution of this spatially floating image depends not only on the resolution of the liquid crystal display panel 11 but also on the outer shape D and 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 x 1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is about 80 μm, the diameter D of the retroreflective part is 240 μm and the pitch is 300 μm. For example, one pixel of the spatial floating image is equivalent to 300 μm. Therefore, 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 equivalent to that of the image display device 1, it is desirable to make the diameter and pitch of the retroreflective portions close to one pixel of the liquid crystal display panel. On the other hand, in order to suppress the occurrence of moiré caused by the retroreflective member and the pixels of the liquid crystal display panel, it is preferable to design the pitch ratio of each of them to be outside an integral multiple of one pixel. Further, the shape of the retroreflective portion is preferably arranged so that no side of the retroreflective portion overlaps any side of one pixel of the liquid crystal display panel.

On the other hand, in order to manufacture the retroreflective member at low cost, it is preferable to mold it using a roll press method. Specifically, this is a method in which the recursive parts are aligned and shaped on the film.The reverse shape of the shape to be shaped is formed on the surface of the roll, and an ultraviolet curing resin is applied on the base material for fixation, and the space between the rolls is By passing it through, it is shaped into a necessary shape and cured by irradiation with ultraviolet rays, thereby obtaining a retroreflective member 2 having a desired shape.

<Second configuration example of spatial floating video information display system>
FIG. 3 is a diagram showing another example of the configuration of the main parts of the spatial floating video information display system according to an embodiment of the present invention. FIG. 3(A) is a diagram showing another embodiment of the spatial floating video information display system. The video display device 1 includes a liquid crystal display panel 11 as a video display element 11, and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics. The liquid crystal display panel 11 is comprised of a small liquid crystal display panel with a screen size of about 5 inches to a large liquid crystal display panel with a screen size of over 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 unit 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 a spatially floating image 3 which is a real image spread out and enlarged from the screen display surface of the liquid crystal display panel 11 (the display size is L1 in the figure). Furthermore, the image light beam reflected by the retroreflective member 2 is polarized, and then transmitted through the convex reflective sheet, further diffused by the effect of the concave shape provided on the other side of the convex surface, and transmitted through the transparent member 100. This results in a spatially floating image L2 enlarged in the diagonal direction of FIG. 3(A). At this time, the magnification M of the spatially floating image is M=L2/L1.

As described above, an optical member having a lens function is provided between the image display element 11 and the retroreflective member 2 or between the retroreflective member 2 and the spatially floating image, and in some cases, this optical member is used as an image display device. By decentering or tilting the retroreflective member from the optical axis connecting the retroreflective members, the size and imaging position of the spatially floating image obtained in the video information system can be arbitrarily set with respect to the optical axis described above. As mentioned above, if the size and imaging position of the spatial floating image are changed using optical members, distortion will occur in the spatial image, but by displaying an image with this distortion corrected on the image display device, the entire image information system will be improved. You can get images without distortion.

A λ/4 plate 21 is provided on the light incidence surface of the retroreflective member 2, and the incident image light is reflected by the retroreflective member 2 and then transmitted through the λ/4 plate 21 again, thereby converting the polarization of the image light. The light is transmitted through the polarization separation member 101 having a convex surface. As a result, a spatial floating image having a size different from that displayed on the liquid crystal display panel can be formed at a position transmitted through the transparent member 100.

<Third configuration example of spatial floating video information display system>
FIG. 3(B) is a diagram showing another example of the spatial floating video information display system. Similar to FIG. 3A, the video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics. The liquid crystal display panel 11 can be configured from a small one with a screen size of about 5 inches to a large liquid crystal display panel with a screen size of more than 80 inches. For example, a polarization separation member 101 that selectively reflects image light of a specific polarization, such as a reflective polarizing plate, is used to transfer image light from the liquid crystal display panel 11 to a retroreflection member (retroreflection unit or retroreflection plate) 2. reflect it towards. The difference from the example in FIG. 2 is that the obtained spatially floating image is enlarged as a virtual image X using a concave mirror 5. The configurations of the video display device 1 and the retroreflective member 2 are the same as those in the embodiment shown in FIGS. 2 and 3(A), and the description thereof will be omitted. Note that in the configuration of FIG. 3(B), the polarization separation member 101 may also have a convex shape.

Here, as explained in FIG. 2, the floating image 3 is formed by light rays with high directivity, so when viewed from the direction of arrow A, the floating image 3 is perceived as a bright image. When viewed from the direction of arrow B, the floating image 3 is not viewed as an image at all. Therefore, in the configuration of FIG. 3(B), when the user views from the direction of arrow B, the floating image 3 is located behind the virtual image X, 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 taking advantage of this characteristic, if the floating image 3 is configured to be positioned behind the virtual image X as shown in FIG. This is preferable than configuring to exclude the floating image 3 because the entire system can be made smaller.

<Fourth configuration example of spatial floating video information display system>
FIG. 4 is a diagram showing another example of the configuration of the main parts of the spatial floating video information display system according to an embodiment of the present invention. Similar to FIG. 3A and the like, the video display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates light of a specific polarization having narrow-angle diffusion characteristics. For example, the liquid crystal display panel 11 is configured from a small one with a screen size of about 5 inches to a large liquid crystal display panel with a screen size of over 80 inches. The folding mirror 22 uses the transparent member 100 as a substrate. On the surface of the transparent member 100 on the image display device 1 side, a polarization separation member 101 such as a reflective polarizing plate that selectively reflects image light of a specific polarization is provided, and the image light from the liquid crystal display panel 11 is separated. It is reflected toward the retroreflector 2. Thereby, the folding mirror 22 has a function as a mirror. Image light of a specific polarization from the image display device 1 is separated from the transparent member 100 by using a polarization separation member 101 (in the illustrated example, a sheet-like polarization separation member 101 provided on the lower surface of the transparent member 100) using an adhesive. ) and enters the retroreflective member 2. Note that instead of the polarization separation member 101, an optical film having polarization separation characteristics may be deposited on the surface of the transparent member 100.

A λ/4 plate 21 is provided on the light incidence surface of the retroreflective member 2, and the image light is passed through it twice to perform polarization conversion and convert a specific polarized wave into the other polarized wave with a phase difference of 90°. As a result, the image light after retroreflection is transmitted through the polarization separation member 101, and a spatial floating image 3, which is a real image, is displayed on the outside of the transparent member 100. Here, in the polarization separation member 101 described above, the polarization axes become uneven due to retroreflection, so a part of the image light is reflected and returns to the image display device 1 . This light is reflected again on the image display surface of the liquid crystal display panel 11 constituting the image display device 1, generating a ghost image and significantly deteriorating the image quality of the spatial floating image.

Therefore, in this embodiment, an absorption type 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. With this configuration, ghosts of spatially floating images can be eliminated. Prevent image quality from deteriorating due to images. Further, in order to reduce image quality deterioration due to sunlight or illumination light outside the set, it is preferable to provide an absorption type polarizing plate 102 on the surface of the transparent member 105 on the image light output side.

Next, a sensor 44 having a TOF (Time of Fly) function is illustrated so as to sense the relationship between the distance and position between the object and the sensor 44 with respect to the spatial floating image obtained by the above-mentioned spatial floating image information system. By arranging them in multiple layers as shown in FIG. 5, it becomes possible to sense not only the coordinates of the object in the plane direction, but also the coordinates in the depth direction, the direction of movement, and the speed of movement of the object.

In order to read two-dimensional distance and position, multiple combinations of non-visible light emitting parts such as infrared or ultraviolet light and light receiving parts are arranged in a straight line, the light from the light emitting points is irradiated onto the target object, and the reflected light is received. The light is received at the The distance to the object is determined by the product of the difference between the time the light is emitted and the time the light is received and the speed of light. Further, the coordinates on the plane can be read from the coordinates of the portion where the difference between the light emission time and the light reception 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 the object on a plane (two-dimensional) and a plurality of the sensors described above.

Furthermore, a method for obtaining a three-dimensional spatially floating image as the above-mentioned spatially floating image information system will be explained using FIG. 6. FIG. 6 is a diagram for explaining the principle of three-dimensional video display used in the spatial floating video 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, in order to display motion parallax from three directions P1, P2, and P3 in the horizontal direction of the screen as shown in FIG. 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), and the light is separated and emitted in three directions. As a result, a three-dimensional image with three parallaxes can be displayed.

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

In addition, in the characteristic graphs of Figures 8 to 11 (each shown in color), the angle (deg) values shown in the right margin are arranged in descending order of the vertical axis, that is, the transmittance (%) value, starting from the top. It shows. 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 addition, 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 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 addition, 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 in the horizontal (H) direction is 0 degrees (deg), the transmittance is highest; The transmittance decreases in this order. In addition, 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 in the horizontal (H) direction is 0 degrees (deg), the transmittance is highest; The transmittance decreases in this order.

As shown in FIGS. 8 and 9, the grid-structured reflective polarizing plate has poor characteristics with respect to 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 the image light emitted from the liquid crystal display panel 11 at a narrow angle, is an ideal light source. Furthermore, similarly to the characteristics in the horizontal direction, the characteristics deteriorate with respect to light from an oblique direction. In consideration of the above characteristics, a configuration example of this embodiment will be described below in which a light source capable of emitting image light from the liquid crystal display panel 11 at a narrower angle is used as a backlight of the liquid crystal display panel 11. This makes it possible to provide high-contrast spatially floating images.

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

As shown by an arrow 30 in FIG. 12, this liquid crystal display panel (video display element 11) uses a light beam from a light source device 13, which is a backlight device, to produce a light beam having a narrow angle diffusion characteristic, that is, a directivity (straight direction). ) is strong and the polarization plane is aligned in one direction to obtain an illumination light beam with characteristics similar to a laser beam, and the image light modulated according to the input video signal is reflected by the retroreflective member 2. The light passes through the window glass 105 to form a spatially floating image that is a real image (see also FIG. 1).

Further, in FIG. 12, a liquid crystal display panel 11 constituting the image display device 1, a light direction conversion panel 54 that adjusts the directivity of the light beam emitted from the light source device 13, and a narrow-angle diffuser plate ( (not shown). That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and the configuration is such that image light of a specific polarization 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 as a highly directional (straight forward) specific polarized light toward the retroreflective member 2 via the light direction conversion panel 54, and after being reflected by the retroreflective member 2, the light is transmitted to the store. The light is transmitted toward the viewer's eyes outside the (space) to form a space floating image 3. Note that 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 emitted light beam 30 from the light source device 13 and significantly reduce power consumption, the video 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, and after being reflected by the retroreflective member 2, a transparent sheet (not shown) provided on the surface of the windshield 105 is projected. ), the directivity can be adjusted to form a floating image at a desired position.

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

<Example 1 of video display device>
FIG. 13 shows an example of a specific configuration of the video display device 1. In FIG. 13, a liquid crystal display panel 11 and a light direction conversion panel 54 are arranged on the light source device 13 of FIG. 12. This light source device 13 is formed of, for example, plastic on the case shown in FIG. 12, and has an LED element 201 and a light guide 203 housed therein. As shown in FIG. 12, etc., 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 with a large area and has the effect of gradually decreasing the divergence angle by undergoing total reflection multiple times while propagating inside.

A liquid crystal display panel 11 is attached above the light guide 203. Furthermore, an LED (Light Emitting Diode) element 201, which is a semiconductor light source, and an LED board 202 mounted with its control circuit are attached to one side surface (in this example, the left end surface) of the case of the light source device 13. 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 board 202.

Further, 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. A flexible printed circuit (FPC) (not shown) and the like are attached thereto. That is, the liquid crystal display panel 11, which is an image display element, together 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 an electronic device. A display image is generated by At this time, the generated image light has a narrow diffusion angle and only has a specific polarization component, resulting in a new, unprecedented image display device that is similar to a surface-emitting laser image source driven by a video signal. .

Note that, at present, it is technically impossible to obtain a laser beam having a size equivalent to that of the image obtained by the video display device 1 described above using a laser device, both technically and from a safety standpoint. Therefore, in this embodiment, for example, light close to the above-mentioned surface emitting laser image light is obtained from a light beam from a general light source including 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 FIG. 14 as well as FIG. 13.

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 approximately collimated light by the shape of the light-receiving end surface 203a of the light guide 203. . Therefore, the light receiving section on the end surface of the light guide and the LED element are attached while maintaining a predetermined positional relationship.

Note that each of the light guides 203 is made of a translucent resin such as acrylic, for example. 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 a parabolic cross section, and at its top, a convex portion (i.e., The lens has a concave portion with a convex lens surface formed thereon, and a convex lens surface protruding outward (or a concave lens surface concave inward) in the center of the flat portion (not shown). Note that the external shape of the light receiving part of the light guide to which the LED element 201 is attached is a paraboloid that forms 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 a circuit board thereof. This LED board 202 is arranged and fixed to the collimator (light-receiving end surface 203a) so that the LED elements 201 on the surface thereof are respectively located at the center of the above-mentioned recess.

According to this configuration, the shape of the light-receiving end surface 203a of the light guide 203 allows the light emitted from the LED element 201 to be extracted as substantially parallel light, and it is possible to improve 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, which are light sources, are arranged to the light receiving end face 203a, which is a light receiving part provided on the end face of the light guide 203. The diverging light flux of , the light is emitted toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front in the drawing). By optimizing the distribution (density) of the light flux direction converting means 204 depending on the shape of the inside or surface of the light guide, the uniformity of the light flux incident on the liquid crystal display panel 11 can be adjusted.

The above-mentioned light flux direction conversion means 204 changes the light flux propagated within the light guide 203 by providing portions with different refractive indexes in the shape of the light guide surface or inside the light guide as shown in FIG. 13 or 14. is emitted toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in a direction perpendicular to the front in the drawing). At this time, if the relative brightness ratio is 20% or more when comparing the brightness of the center of the screen and the periphery of the screen with the liquid crystal display panel 11 facing directly at the center of the screen and the viewpoint placed at the same position as the diagonal dimension of the screen, it is practical. There is no problem, and if it exceeds 30%, the characteristics will be even better.

Note that FIG. 13 is a cross-sectional layout diagram for explaining the structure and operation of the light source of this embodiment that converts polarization 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 having a light beam direction converting means 204 on its surface or inside, an LED element 201 as a light source, a reflective sheet 205, a retardation plate 206, It is made up of a lenticular lens, etc., and a liquid crystal display panel 11 is attached to its upper surface, which has polarizing plates on the light source light incident surface and the image light exit surface.

Further, a reflective polarizing plate 49 in the form of a film or sheet is provided on the light source light incident surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, so that a portion of the natural light flux 210 emitted from the LED element 201 is The polarized wave (for example, P wave) 212 on one side is selectively reflected, reflected by a reflective sheet 205 provided on one (lower side of the figure) surface of the light guide 203, and directed toward the liquid crystal display panel 11 again. Make it. 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 reflection is reflected by the reflective sheet 205 and passed twice. The reflected light flux is converted from P-polarized light to S-polarized light, thereby improving the efficiency of using the light source light as image light.

The image light beam whose light intensity is modulated by the image signal on the liquid crystal display panel 11 (arrow 213 in FIG. 13) enters the retroreflective member 2, and as shown in FIG. 1, after reflection, it passes through the window glass 105. It is possible to obtain a real spatial floating image inside or outside the store (space).

Similar to FIG. 13, FIG. 14 is a cross-sectional layout diagram for explaining the configuration and operation of the light source of this embodiment that converts polarization in the light source device 13 including the light guide 203 and the LED element 201. The light source device 13 similarly includes a light guide 203 formed of plastic or the like and having a light beam direction converting means 204 on its surface or inside, an LED element 201 as a light source, a reflective sheet 205, a retardation plate 206, and a lenticular lens. It is composed of etc. On the light guide 203, a liquid crystal display panel 11 is attached as an image display element, which includes polarizing plates on a light source light incident surface and an image light exit surface.

Further, a reflective polarizing plate 49 in the form of a film or sheet is provided on the light source light incident surface (lower surface in the figure) of the liquid crystal display panel 11 corresponding to the light source device 13, and one side of the natural light flux 210 emitted from the LED light source 201 is polarized. Waves (for example, S waves) 211 are 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 the light is reflected by passing it twice. The light beam is converted from S-polarized light to P-polarized light, and the efficiency of using the light source light as image light is improved. The image light beam whose intensity is modulated by the image signal on the liquid crystal display panel 11 (arrow 214 in FIG. 14) enters the retroreflective member 2, and as shown in FIG. It is possible to obtain a space floating image that is a real image inside or outside (space).

In the light source devices shown in FIGS. 13 and 14, in addition to the action of the polarizing plate provided on the light incident surface of the corresponding liquid crystal display panel 11, the reflective polarizing plate 49 reflects the polarized light 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 fact, it has been confirmed through experiments that the contrast performance of displayed images is improved by more than 10 times. As a result, high-quality images comparable to those of self-luminous organic EL were obtained.

<Example 2 of video display device>
FIG. 15 shows another example of a specific configuration of the video display device 1. The light source device 13 in FIG. 15 is similar to 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 has a liquid crystal display panel 11 attached to its upper surface. Furthermore, an LED board on which LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and their control circuits are mounted is attached to one side of the case of the light source device 13, and an LED board is mounted on the outer side of the LED board. A heat sink 103, which is a member for cooling the heat generated by the LED elements and the control circuit, is attached (see also FIGS. 17, 18, etc.).

In addition, the liquid crystal display panel frame attached to the top surface of the case includes the liquid crystal display panel 11 attached to the frame and an FPC (Flexible Printed Circuit) electrically connected to the liquid crystal display panel 11. ) 403 (see FIG. 7), etc. are attached. That is, the liquid crystal display panel 11 that is a liquid crystal display element, together with the LED elements 14a and 14b that 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 an electronic device. A display image is generated by modulating the .

<Example 1 of light source device of 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. 18(a) and 18(b) as well as FIG. 17.

17 and 18 show LEDs 14a and 14b constituting a light source, which are attached to a predetermined position with respect to the collimator 15. Note that each of the collimators 15 is made of a translucent resin such as acrylic. As shown in FIG. 18(b), this collimator 15 has an outer circumferential surface 156 with a conical convex shape obtained by rotating a parabolic cross section, and the center of the collimator 15 at its top (the side in contact with the LED board). It has a concave portion 153 in which a convex portion (that is, a convex lens surface) 157 is formed.

The collimator 15 has a convex lens surface (or a concave lens surface recessed inward) 154 that protrudes outward at the center of the plane portion (the side opposite to the above-mentioned top portion). Note that the paraboloid 156 forming the conical outer circumferential surface of the collimator 15 is set within an angle range that allows total reflection of the light emitted from the LEDs 14a and 14b in the peripheral direction, or, A reflective surface is formed.

Further, the LEDs 14a and 14b are respectively arranged at predetermined positions on the surface of the LED board 102, which is the circuit board thereof. This LED board 102 is arranged and fixed to the collimator 15 such that the LEDs 14a or 14b on the surface thereof are located at the center of the recess 153, respectively.

According to this configuration, among the light emitted from the LED 14a or 14b by the collimator 15 described above, especially the light emitted upward (to the right in the figure) from the central portion thereof, the outer shape of the collimator 15 is The two convex lens surfaces 157 and 154 converge the light into parallel light. Further, light emitted from other parts toward the periphery is reflected by the paraboloid that forms the conical outer peripheral surface of the collimator 15, and is similarly condensed into parallel light. In other words, with the collimator 15 having a convex lens in the center and a paraboloid in the periphery, it is possible to extract almost all of the light generated by the LED 14a or 14b as parallel light. , it becomes possible to improve the utilization efficiency of the generated light.

Note that a polarization conversion element 21 is provided on the light output side of the collimator 15. The polarization conversion element 21 may also be referred to as a polarization conversion member. As is clear from FIG. 18, this polarization conversion element 21 consists of a columnar light-transmitting member having a parallelogram cross section (hereinafter referred to as a parallelogram column) and a columnar member having a triangular cross section (hereinafter referred to as a triangular column). ) and are arranged in a plurality in an array parallel to a plane perpendicular to the optical axis of the parallel light from the collimator 15. Furthermore, polarizing beam splitters (hereinafter abbreviated as "PBS films") 211 and reflective films 212 are alternately provided at the interfaces between adjacent light-transmitting members arranged in an array. Further, 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 exits.

The output surface of this polarization conversion element 21 is further provided with a rectangular synthetic diffusion block 16, also shown in FIG. 18(a). That is, the light emitted from the LED 14a or 14b becomes parallel light due to the action of the collimator 15, enters the composite diffusion block 16, is diffused by the texture 161 on the exit side, and then reaches the light guide 17.

The light guide 17 is a rod-shaped member with a substantially triangular cross section (see FIG. 18(b)) made of a translucent resin such as acrylic, and as is clear from FIG. A light guide light incident part (surface) 171 facing the output surface of the diffusion block 16 via the first diffuser plate 18a, a light guide light reflection part (surface) 172 forming a slope, and a second diffuser. A light guide light emitting portion (surface) 173 is provided, which faces the liquid crystal display panel 11, which is a liquid crystal display element, through the plate 18b.

As shown in FIG. 17, which is a partially enlarged view, the light guide light reflecting portion (surface) 172 of the light guide 17 has a large number of reflecting surfaces 172a and connecting surfaces 172b alternately arranged in a sawtooth shape. It is formed. The reflective surface 172a (line segment sloping upward to the right in the figure) forms αn (n: a natural number, for example, 1 to 130) with respect to the horizontal plane indicated by the dashed line in the figure. 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 part (surface) 171 of the light guide 17 is formed into a curved convex shape inclined toward the light source, as shown in FIG.

According to the light source device 13 configured as described above, the parallel light emitted from the output surface of the composite diffusion block 16 is diffused via the first diffusion plate 18a and reaches the light guide entrance portion of the light guide 17. (plane) 171. As is clear from FIG. 17, the light incident on the light guide 17 is slightly bent (deflected) upward when it enters the light guide incident part (surface) 171, and then passes through the light guide light reflection part ( The light reaches the light guide surface (surface) 172, is reflected by the reflective surface (172a) of the light guide light reflecting portion (surface) 172, and reaches the liquid crystal display panel 11 provided on the upper output surface in FIG.

According to the video display device 1 described in detail above, it is possible to further improve the light utilization efficiency and its uniform illumination characteristics, and at the same time, it can be manufactured in a small size and at low cost, including a modular S-polarized light source device. It becomes possible. In the above description, the polarization conversion element 21 was described as being attached after the collimator 15, but the present invention is not limited thereto, and the same effect can be achieved by providing it in the optical path leading to the liquid crystal display panel 11. Effects and effects can be obtained.

Note that the light guide light reflecting portion (surface) 172 has a large number of reflecting surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth shape, and the illumination light flux is totally reflected on each reflecting surface 172a. Furthermore, a narrow-angle diffuser plate is provided on the light guide light emitting part (surface) 173, and the light enters the light direction conversion panel 54 that adjusts the directivity as a substantially parallel diffused light flux, and from an oblique direction. The light enters the liquid crystal display panel 11. In this embodiment, the light direction conversion panel 54 is provided between the light guide output surface 173 and the liquid crystal display panel 11, but the same effect can be obtained even if it is provided on the output surface of the liquid crystal display panel 11.

<Example 2 of light source device of 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. mounted in position. Note that each of the collimators 15 is made of a translucent resin such as acrylic. Similarly to the example shown in FIG. 18, this collimator 15 has an outer circumferential surface 156 with a conical convex shape obtained by rotating a parabolic cross section, and has a convex portion (i.e., It has a concave portion 153 in which a convex lens surface 157 is formed. Further, in the center of the plane part, there is a convex lens surface (or a concave lens surface concave inward) 154 that projects outward. Note that the paraboloid 156 forming the conical outer peripheral surface of the collimator 15 is set within an angle range that allows total internal reflection of the light emitted from the LED 14a in the peripheral direction, or is set as a reflective surface. is formed.

Further, the LEDs 14a and 14b are respectively arranged at predetermined positions on the surface of the LED board 102, which is the circuit board thereof. This LED board 102 is arranged and fixed to the collimator 15 such that the LEDs 14a or 14b on the surface thereof are located at the center of the recess 153, respectively.

According to this configuration, among the light emitted from the LED 14a or 14b by the collimator 15 described above, especially the light emitted upward (to the right in the figure) from the central portion thereof, the outer shape of the collimator 15 is The two convex lens surfaces 157 and 154 converge the light into parallel light. Further, light emitted from other parts toward the periphery is reflected by the paraboloid that forms the conical outer peripheral surface of the collimator 15, and is similarly condensed into parallel light. In other words, with the collimator 15 having a convex lens in the center and a paraboloid in the periphery, it is possible to extract almost all of the light generated by the LED 14a or 14b as parallel light. , it becomes possible to improve the utilization efficiency of the generated light.

Note that a light guide 170 is provided on the light output side of the collimator 15 via a first diffuser plate 18a. The light guide 170 is a rod-shaped member with a substantially triangular cross section (see FIG. 19(a)) made of a translucent resin such as acrylic, and as is clear from FIG. 19(a). , an incident part (surface) 171 of the light guide light 170 facing the output surface of the diffusion block 16 via the first diffuser plate 18a, and a light guide light reflection part (surface) 172 forming a slope; It includes a light guide light emitting part (surface) 173 that faces a liquid crystal display panel 11 which is a liquid crystal display element with a reflective polarizing plate 200 interposed therebetween.

If this reflective polarizing plate 200 is selected to have a property of reflecting P-polarized light (transmitting S-polarized light), for example, it will reflect P-polarized light out of the natural light emitted from the LED that is the light source, as shown in FIG. 19(b). It passes through the λ/4 plate 202 provided in the light guide light reflecting section 172 shown in FIG. All the light beams incident on the light beam are unified into S-polarized light.

Similarly, if a reflective polarizing plate 200 is selected that has the property of reflecting S-polarized light (transmitting P-polarized light), it will reflect S-polarized light out of the natural light emitted from the LED as the light source, as shown in FIG. 19(b). It passes through the λ/4 plate 202 provided in the light guide light reflecting section 172 shown in FIG. All the light beams incident on the light beam 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 using FIG. 16. The light source device of this image display device 1 converts the diverging light flux of light (P polarized light and S polarized light mixed) from the LED into a substantially parallel light flux using the collimator 18, and uses the reflective surface of the reflective light guide 304 to display the liquid crystal display panel. Reflect towards 11. The reflected light enters a reflective polarizing plate 49 placed between the liquid crystal display panel 11 and the reflective light guide 304 .

A specific polarized light (for example, P-polarized light) is transmitted through the reflective polarizing plate 49 and enters the liquid crystal display panel 11 . The other polarized light (for example, S-polarized light) is reflected by the reflective polarizing plate and heads toward 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 reflective 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 transmission surface of the reflective light guide 304 passes through the back surface of the reflective light guide 304, passes through the λ/4 plate 270, which is a retardation plate, and is reflected by the reflection plate 271. The light reflected by the reflection plate 271 passes through the λ/4 plate 270 again, and then passes through the transmission surface of the reflective light guide 304. The light transmitted through the transmission surface of the reflective light guide 304 enters the reflective polarizing plate 49 again.

At this time, the light that enters the reflective polarizing plate 49 again passes through the λ/4 plate 270 twice, so the polarization is converted to polarized light (for example, P polarized light) that passes through the reflective polarizing plate 49. ing. Therefore, the polarized light passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11. Note that with respect to polarization design related to polarization conversion, the polarization may be configured to be reversed (S-polarized light and P-polarized light are reversed) from the above explanation.

As a result, the light from the LED is aligned to a specific polarization (for example, P polarization), enters the liquid crystal display panel 11, and is modulated in brightness according to the video signal to display an image on the panel surface. As in the above example, a plurality of LEDs constituting the light source are provided (however, only one LED is shown in FIG. 16 due to the vertical section), and these are placed at a predetermined position with respect to the collimator 18. installed.

Note that the collimators 18 are each made of a translucent resin such as acrylic, or glass. The collimator 18 may have a conical convex outer peripheral surface obtained by rotating a parabolic cross section. The top portion may have a concave portion with a convex portion (ie, a convex lens surface) formed in the center thereof. Further, the central portion of the flat portion has a convex lens surface projecting outward (or a concave lens surface concave inward). Note that the paraboloid that forms the conical outer circumferential 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 parabolic surface is It is formed.

Note that the LEDs are arranged at predetermined positions on the surface of the LED board 102, which is a circuit board thereof. This LED board 102 is arranged and fixed to the collimator 18 so that the LEDs on its surface are located at the center of the conical convex top (or in the recess if the top has a recess). Ru.

According to this configuration, among the light emitted from the LED by the collimator 18, especially the light emitted from the central portion thereof is focused by the convex lens surface forming the outer shape of the collimator 18, and becomes parallel light. Further, the light emitted toward the peripheral direction from other parts is reflected by the paraboloid that forms 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 center and a paraboloid in its periphery, makes it possible to extract almost all of the light generated by the LED as parallel light. This makes it possible to improve the efficiency of using the light.

The above configuration is similar to the light source device of the video display device shown in FIGS. 17, 18, etc. 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, a specific polarized light is transmitted through the reflective polarizing plate 49 by the action of the reflective polarizing plate 49, and the other polarized light 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 a reflection plate 271 located at a position opposite to the liquid crystal display panel 11 with respect to the reflective light guide 304 . At this time, the light passes twice through the λ/4 plate 270, which is a retardation plate, to undergo polarization conversion.

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 passes through the reflective polarizing plate 49 and enters the liquid crystal display panel 11 with the polarization direction aligned. As a result, all the light from the light source can be used, so the geometrical optical usage efficiency of light is doubled. Further, since the degree of polarization (extinction ratio) of the reflective polarizing plate is added to the extinction ratio of the entire system, by using the light source device of this embodiment, the contrast ratio of the entire display device is significantly improved.

Note that by adjusting the surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflective plate 271, the angle of reflection and diffusion of light on each reflective surface can be adjusted. The surface roughness of the reflective surface of the reflective light guide 304 and the surface roughness of the reflector plate 271 may be adjusted for each design so that the uniformity of light incident on the liquid crystal display panel 11 becomes more suitable.

In the example explained with reference to FIG. 16, the λ/4 plate 270, which is a retardation plate, has a configuration in which the phase difference with respect to polarized light incident perpendicularly to the λ/4 plate 270 is λ/4, but this is not necessarily the case. It is not necessary to have such a configuration. In the configuration of FIG. 16, the λ/4 plate 270 may be any retardation plate whose phase changes by 90° (λ/2) when polarized light passes through it twice. Further, the thickness of the retardation plate may be adjusted depending on the incident angle distribution of polarized light.

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

Specifically, on the light output side of the collimator 18, two optical sheets are used (an optical sheet 207A and an optical sheet 207B), the light from the collimator 18 is made to enter between two optical sheets (diffusion sheets). The number of this optical sheet may be one instead of two. In the case of a single optical sheet configuration, the vertical and horizontal diffusion characteristics are adjusted by the fine shapes on the front and back surfaces of the single optical sheet.

Alternatively, a configuration may be adopted in which a plurality of diffusion sheets are used and the diffusion function is shared among each diffusion sheet. Here, in the example of FIG. 25, the number of LEDs is adjusted so that the surface density of the luminous flux emitted from the liquid crystal display panel 11 is uniform, regarding the reflection and diffusion characteristics due to the surface shape and back surface shape of the optical sheet 207A and the optical sheet 207B. It is preferable to optimally design the divergence angle from the LED board (optical element) 102 and the optical specifications of the collimator 18 as design parameters. 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 display example 3 described above. That is, in the example of FIG. 25, the reflective polarizing plate 49 may be configured to have a characteristic of reflecting S-polarized light (transmitting P-polarized light). In that case, the P-polarized light of the light emitted from the LED serving as 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 a light source, S-polarized light is reflected, and the reflected light passes through a retardation plate 270 shown in FIG.

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

In a device for general TV use, the light emitted from the liquid crystal display panel 11 has, for example, the "conventional characteristic (X direction)" in FIG. 22(A) and the "conventional characteristic (Y direction)" in FIG. 22(B). '', the screen horizontal direction (display direction corresponding to the X-axis of the graph in FIG. 22(A)) and the screen vertical direction (display direction corresponding to the Y-axis of the graph in FIG. 22(B)) and have similar diffusion characteristics.

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

In one specific example, if the viewing angle is set to 13 degrees at which the brightness is 50% of the brightness when viewed from the front (angle of 0 degrees) (brightness reduced by about half), The angle is approximately 1/5 of the diffusion characteristic (angle of 62 degrees) of a device for TV use. Similarly, in an example where the vertical viewing angle is set unevenly between the upper and lower sides, the upper viewing angle may be suppressed (narrowed) to about 1/3 of the lower viewing angle. , optimize the reflection angle of the reflective light guide, the area of the reflective surface, etc.

By setting the viewing angle, etc. as described above, compared to conventional LCD TVs, the amount of light directed toward the user's viewing direction is significantly increased (significantly improved in terms of image brightness). The brightness of such an image is 50 times or more.

Furthermore, in the case of the viewing angle characteristics shown in "Example 2" in FIG. 22, the viewing angle is such that the brightness is 50% of the brightness of the image obtained in front view (angle of 0 degrees) (brightness reduced to approximately half). If it is set to be 5 degrees, the angle will be about 1/12 (narrow viewing angle) of the diffusion characteristic (angle of 62 degrees) of a device for general home TV use. Similarly, in an example where the vertical viewing angle is set equally on the upper and lower sides, reflective type Optimize the reflection angle of the light guide and the area of the reflection surface.

By making these settings, the brightness (amount of light) of images directed toward the viewing direction (direction of the user's line of sight) is significantly improved compared to conventional LCD TVs, and the brightness of such images is more than 100 times higher. .

As described above, by making the viewing angle a narrow angle, the amount of luminous flux directed toward the viewing direction can be concentrated, so that the efficiency of light utilization is greatly improved. As a result, even if a liquid crystal display panel for general TV use is used, by adjusting the light diffusion characteristics of the light source device, it is possible to achieve a significant increase in brightness with the same power consumption. It can be a video display device compatible with the display system.

When using a large LCD panel, the light around the screen is directed inward toward the viewer when the center of the screen is directly facing the viewer, thereby increasing the overall brightness of the screen. will improve. FIG. 20 shows the long side of the liquid crystal display panel and the short side of the liquid crystal display panel when the distance L from the liquid crystal display panel to the viewer and the panel size of the video display device (screen ratio 16:10) are used as parameters. The convergence angle is calculated.

The diagram shown in the upper part of FIG. 20 assumes that the image is viewed with the screen of the liquid crystal display panel in portrait orientation (hereinafter also referred to as "portrait orientation"). In this case, the convergence angle may be set in accordance with the short side of the liquid crystal display panel (as appropriate, refer to the direction of arrow V in FIG. 20). 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. As a result, image light from each corner (four corners) of the screen can be effectively projected or output toward the viewer.

Similarly, when viewing a 15" panel vertically and the viewing distance is 0.8m, setting the convergence angle to 7 degrees will effectively direct the image light from the four corners of the screen toward the viewer. As mentioned above, depending on the size of the LCD panel and whether it is used vertically or horizontally, the image light around the screen can be directed to the viewer who is in the optimal position to view the center of the screen. , the overall screen brightness can be improved.

As for the basic configuration, as shown in FIG. A spatially floating image obtained by reflecting the image information displayed above on a retroreflective member is displayed outdoors or indoors via a transparent member 100.

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

<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 a portion of the liquid crystal display panel 11 and the diffusion plate 206 are omitted in order to explain the light guide 311.

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

As shown in FIG. 26(a), the LEDs 14 are arranged in a line 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. Note that 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 formed 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 (the right side in the figure) of the reflector 300 is a reflecting surface in the shape of a paraboloid cut along the meridian plane (hereinafter sometimes referred to as a "paraboloid"). ) 305. The reflector 300 converts the diverging light emitted from the LED 14 into approximately parallel light by reflecting it on the reflecting surface 305 (paraboloid), and the converted light enters the end surface of the light guide 311. let In one specific example, light guide 311 is a transmissive light guide.

The reflective surface of the reflector 300 has an asymmetrical shape with respect to the optical axis of the light emitted from the LED 14. Further, the reflective 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 reflected light beam is converted into substantially parallel light.

Since the LED 14 is a surface light source, even if it is placed at the focal point of a paraboloid, the diverging light from the LED cannot be converted into completely parallel light, but this does not affect the performance of the light source of the present invention. The LED 14 and the reflector 300 are a pair, and in order to ensure the specified performance with the mounting accuracy of the LED 14 to the board 102 of ±40 μm, the number of LEDs to be mounted on the board should be no more than 10 at most, considering mass production. If so, it's best to keep it to around 5.

Although the LED 14 and the reflector 300 are partially located close to each other, heat can be radiated to the space on the opening side of the reflector 300, so that the temperature rise of the LED can be reduced. Therefore, the reflector 300 made of plastic molding can be used. As a result, the shape accuracy of the reflecting surface can be improved by more than 10 times compared to a reflector made of glass material, so 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 beam by the reflector 300, then reflected by the reflective surface, and is placed opposite the light guide 311. The light is emitted toward the liquid crystal display panel 11. As shown in FIG. 26, the reflective surface provided on the bottom surface 303 may have a plurality of surfaces having different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces having different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300.

Further, the shape of the reflective surface provided on the bottom surface 303 may be a planar shape. At this time, the refracting surface 314 provided on the surface of the light guide 311 facing the liquid crystal display panel 11 refracts the light reflected by the reflective surface provided on the bottom surface 303 of the light guide 311, so that the liquid crystal display panel 11 The light intensity and emission direction of the luminous flux directed toward the target are adjusted with high precision.

As shown in FIG. 26, the refracting surface 314 may have a plurality of surfaces having different inclinations in the traveling direction of the parallel light beam from the reflector 300. Each of the plurality of surfaces having different inclinations may have a shape extending in a direction perpendicular to the traveling direction of the parallel light beam from the reflector 300. The inclinations of the plurality of surfaces cause the light reflected by the reflective surface provided on the bottom surface 303 of the light guide 311 to be refracted toward the liquid crystal display panel 11 . Further, the refraction surface 314 may be a transmission surface.

Note that when the diffuser plate 206 is provided in front of the liquid crystal display panel 11, the light reflected by the reflective surface is refracted toward the diffuser plate 206 by the plurality of inclinations of the refracting surface 314. That is, the extending direction of the plurality of surfaces having different inclinations of the refractive surface 314 and the extending direction of the plurality of surfaces having different inclinations of the reflective surface provided on the bottom surface 303 are parallel. By making both stretching directions parallel, the angle of light can be adjusted more suitably. On the other hand, the LED 14 is soldered to the metallic substrate 102. Therefore, the heat generated by the LED can be radiated into the air through the substrate.

Further, the reflector 300 may be in contact with the substrate 102, but a space may be left open. When opening a space, the reflector 300 is placed in a state where it is adhered to the casing. By leaving 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, thereby maintaining luminous efficiency and extending the lifespan.

<Another example 2 of light source device>
Next, we will discuss the configuration of an optical system for a light source device that uses polarization conversion to improve light utilization efficiency by 1.8 times compared to the light source device shown in FIG. 26. This will be described in detail with reference to 1)(2) and FIGS. 27C and 27D(1)(2). Note that the illustration of the sub-reflector 308 is omitted in FIG. 27A(1).

27A, FIG. 27B, and FIG. 27C show a state in which the LED 14 constituting the light source is attached to the substrate 102, and these are configured by a unit 312 having a plurality of blocks, including a reflector 300 and the LED 14 as a pair of blocks. .

Among these, the base material 320 shown in FIG. 27A(2) is the base material of the substrate 102. Generally, the metallic substrate 102 has heat, so in order to insulate (insulate) the heat of the substrate 102, the base material 320 is preferably made of a plastic material or the like. The material of the reflector 300 and the shape of the reflecting surface may be the same as those of the example of the light source device in FIG. 26 .

Further, the reflective surface of the reflector 300 may have a shape asymmetrical with respect to the optical axis of the emitted light of the LED 14. The reason for this will be explained with reference to FIG. 27A(2). In this embodiment, the reflective 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 point of the paraboloid.

Further, due to the characteristics of the paraboloid, the light emitted from the four corners of the light emitting surface also becomes a substantially parallel light beam, and the only difference is in the emission direction. Therefore, even if the light emitting section has a large area, the amount of light incident on the polarization conversion element 21 and the conversion efficiency are hardly affected as long as the distance between the polarization conversion element disposed at the subsequent stage and the reflector 300 is short.

Further, even if the mounting position of the LED 14 is shifted from the focal point of the corresponding reflector 300 within the XY plane, an optical system can be realized that can reduce the decrease in light conversion efficiency for the above-mentioned reasons. Furthermore, even if the mounting position of the LED 14 varies in the Z-axis direction, the converted parallel light beam only moves within the ZX plane, and the mounting accuracy of the LED, which is a surface light source, can be significantly reduced. In this embodiment as well, a reflector 300 having a reflecting surface formed by cutting out a part of a paraboloid in a meridian direction has been described, but an LED may be placed in a part of the entire paraboloid which is cut out as a reflecting surface.

On the other hand, in this embodiment, as shown in FIGS. 27B(1) and 27C, after the diverging light from the LED 14 is reflected by the paraboloid 321 and converted into substantially parallel light, the polarization conversion element 21 in the subsequent stage is The characteristic configuration is that the light is made incident on the end face and aligned to a specific polarization by the polarization conversion element 21. Due to this characteristic configuration, in the present invention, the light utilization efficiency is 1.8 times that of the example shown in FIG. 26 described above, and a highly efficient light source can be realized.

Note that at this time, the substantially parallel light obtained by reflecting the diverging light from the LED 14 on the paraboloid 321 is not all uniform. Therefore, by adjusting the angular distribution of the reflected light using the reflective surfaces 307 having a plurality of inclinations, the reflected light can be directed toward the liquid crystal display panel 11 in a direction perpendicular to the liquid crystal display panel 11 .

In the example shown in this figure, the arrangement is such that the direction of light (principal ray) entering the reflector from the LED and the direction of light entering the liquid crystal display panel are approximately parallel. This arrangement is easy to arrange in terms of design, and it is more preferable to arrange the heat source under the light source device because the temperature rise of the LED can be reduced by allowing air to escape upward.

In addition, as shown in FIG. 27B (1), in order to improve the capture rate of the diverging light from the LED 14, the light flux that cannot be captured by the reflector 300 is reflected by the sub-reflector 308 provided on the light shielding plate 309 disposed above the reflector. The light is reflected by the slope of the lower sub-reflector 310 and enters the effective area of the polarization conversion element 21 in the subsequent stage, further improving the light utilization efficiency. That is, in this embodiment, a part of the light reflected by the reflector 300 is reflected by the sub-reflector 308, and the light reflected by the sub-reflector 308 is reflected by the sub-reflector 310 in the direction toward the light guide 306.

In this way, the substantially parallel light beam aligned to a specific polarization by the polarization conversion element 21 is arranged opposite to the output 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 intensity distribution of the luminous flux incident on the liquid crystal display panel 11 is determined by the shape and arrangement of the reflector 300, the shape (cross-sectional shape) of the reflective surface of the reflective light guide, the inclination of the reflective surface, the surface roughness, etc. Determined by prior setting or adjustment (optimal design). In other words, by optimizing the settings or adjustment items described above, the light amount distribution of the luminous 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 facing the output surface of the polarization conversion element, and the inclination, area, and shape of the reflection surface are determined depending on the distance from the polarization conversion element 21. By optimizing the height and pitch, the light intensity distribution of the light flux incident on the liquid crystal display panel 11 can be set to a desired value, as described above.

By configuring the reflective surface 307 provided on the reflective light guide to have multiple inclinations on one surface, as shown in FIG. 27B (2), it is possible to adjust the reflected light with higher precision. . In addition, in the case of a configuration in which the reflective surface has a plurality of inclinations on one surface, the region used as the reflective surface may be a plurality of surfaces, a polysurface, or a curved surface. Furthermore, the diffusion effect of the diffusion plate 206 realizes a more uniform light amount distribution. The light incident on the diffuser plate on the side closer to the LED achieves a uniform light intensity distribution by changing the inclination of the reflecting surface.

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

In this embodiment as well, although the LED 14 and the reflector 300 are partially located close to each other, heat can be radiated to the space on the opening side of the reflector 300, thereby reducing the temperature rise of the LED. Further, 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 close to the liquid crystal display panel 11, which may make layout difficult. Therefore, as shown in the figure, if the substrate 102 is placed below the reflector 300 (on the side far from the liquid crystal display panel 11), the internal structure of the device will be simpler.

A light shielding plate 410 may be provided on the light incidence surface of the polarization conversion element 21 to prevent unnecessary light from entering the optical system at the subsequent stage. With 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 uniformly polarized light beam, and the part whose polarization direction has been rotated when reflected by the reflective light guide. The light is absorbed by the polarizing plate on the incident side. Furthermore, the temperature of the liquid crystal display panel 11 also rises due to absorption by the liquid crystal itself and temperature rise due to light incident on the electrode pattern, but if there is sufficient space between the reflective surface of the reflective light guide 306 and the liquid crystal display panel 11. 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 modified example of a part of the light source device of FIG. 27B(1). The other configurations are the same as those of the light source device described above in FIG. 27B(1), so illustration and repeated description will be omitted.

First, in the example shown in FIG. 27D (1), the height of the recess 319 of the sub-reflector 310 is such that the principal ray of fluorescence outputted laterally (X-axis direction) from the phosphor 114 (in FIG. 27D (1) (see a straight line extending in a direction parallel to the axis) is adjusted to be at a position lower than the phosphor 114 so that it passes through the recess 319 of the sub-reflector 310. Furthermore, in the Z-axis direction with respect to the position of the phosphor 114, so that the chief ray of fluorescence outputted laterally from the phosphor 114 enters the effective area of the polarization conversion element 21 without being blocked by the light shielding plate 410. The height of the light shielding plate 410 is adjusted to be low.

Further, the reflective surface of the uneven convex portion on the top of the sub-reflector 310 reflects the light reflected by the sub-reflector 308 in order to guide the light reflected by the sub-reflector 308 to the light guide 306 . Therefore, the height of the convex portion 318 of the sub-reflector 310 is adjusted so that the light reflected by the sub-reflector 308 is reflected and enters the effective area of the polarization conversion element 21 in the subsequent stage, thereby further improving the light utilization efficiency. can be improved.

Note that, as shown in FIG. 27A(2), the sub-reflector 310 is arranged extending in one direction, and has an uneven shape. Further, on the top of the sub-reflector 310, irregularities having one or more recesses are periodically arranged in one direction. By forming such an uneven shape, it is possible to configure such that the chief ray of fluorescence outputted laterally from the phosphor 114 enters the effective area of the polarization conversion element 21.

Further, the uneven shape of the sub-reflector 310 is arranged periodically at a pitch such that the recesses 319 are located at the positions where the LEDs 14 are located. That is, each of the phosphors 114 is arranged periodically along one direction corresponding to the pitch of the arrangement of the concave and convex portions of the sub-reflector 310. In addition, when the phosphor 114 is included in the LED 14, the phosphor 114 may be expressed as a light emitting part of a light source.

Moreover, FIG. 27D(2) shows a modified example of a part of the light source device of FIG. 27C. The other configurations are the same as those of the light source device in FIG. 27C, so illustration and repeated description will be omitted. As shown in FIG. 27D (2), the sub-reflector 310 may not be provided, but as in FIG. 27D (1), the principal ray of fluorescence output sideways from the phosphor 114 is not blocked by the light shield 410. The height of the light shielding plate 410 is adjusted to be lower in the Z-axis direction with respect to the position of the phosphor 114 so that the light enters the effective area of the polarization conversion element 21.

Regarding the light source devices in FIGS. 27A, 27B, 27C, and 27D, as shown in 27A(1), dust may enter 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 entering the outside of the light source device, and to prevent stray light from entering from outside the light source device. When the side wall 400 is provided, it is arranged so as to sandwich the space between the light guide 306 and the diffusion plate 206.

A light exit surface of the polarization conversion element 21 that outputs the light polarization-converted by the polarization conversion element 21 faces a space surrounded by the side wall 400, the light guide 306, the diffuser plate 206, and the polarization conversion element 21. Also, of the inner surface of the side wall 400, a portion that covers from the side the space where light is output from the output surface of the polarization conversion element 21 (the space on the right side from the output 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 side wall 400 facing the space includes a reflective region having a reflective film. By making the part 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.

Among the inner surfaces of the side wall 400, the surface that covers the polarization conversion element 21 from the side is a surface with low light reflectance (such as a black surface without a reflective film). This is because when reflected light occurs on the side surface of the polarization conversion element 21, light with an unexpected polarization state is generated, causing stray light. In other words, by making the above-mentioned surface a surface with low light reflectance, it is possible to prevent or suppress the generation of stray light in an image and light with an unexpected polarization state. Further, the cooling effect may be improved by forming a hole in a part of the side wall 400 through which air passes.

Note that the light source devices in FIGS. 27A, 27B, 27C, and 27D have been described on the assumption 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 light source device>
Next, the configuration of an optical system related to a light source device using a reflective light guide 304 based on the light source device shown in Example 1 of the light source device is shown in FIGS. 28A (1), (2), (3), and FIG. This will be explained in detail with reference to 28B.

FIG. 28A shows a state in which the LED 14 constituting the light source is mounted on the substrate 102, and the collimator 18 and the LED 14 form a pair of blocks, and the unit 328 has a plurality of blocks. Since the collimator 18 of this embodiment is close to the LED 14, a glass material is used in consideration of heat resistance. The shape of the collimator 18 is similar to the shape described for the collimator 15 in FIG. Furthermore, by providing a light shielding plate 317 before entering the polarization conversion element 21, unnecessary light is prevented or suppressed from entering the optical system at 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 therefore, repeated explanations will be omitted. The light source device in FIG. 28A may be provided with side walls in the same manner as described in FIGS. 27A, 27B, and 27C. The configuration and effects of the side walls have already been explained, so repeated explanations will be omitted.

FIG. 28B is a cross-sectional view of FIG. 28A(2). The structure of the light source shown in FIG. 28B is common to a part of the structure of the light source in FIG. 18, and has already been explained in FIG. 18, so repeated explanation will be omitted.

<Another example 4 of light source device>
Next, the light source device of FIG. 29 is constituted by a unit 328 having a plurality of blocks as a pair of blocks including the collimator 18 and the LED 14 used in the light source device shown in FIG. 28. The configuration of the optical system related to the light source device using the LEDs and the reflective light guide 504 arranged at both ends of the back surface of the liquid crystal display panel 11 will be explained in detail with reference to FIGS. 29(a), (b), and (c). explain.

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

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

The light emitted from the LED 14 enters the polarization conversion element 501 via the collimator 18. In this example, the configuration is such that the shape of the optical element 81 adjusts the distribution of light incident on the reflective light guide 504 at the subsequent stage. That is, the light intensity distribution of the light beam incident on the liquid crystal display panel 11 is determined by the shape of the collimator 18, the arrangement and shape of the optical element 81, the diffusion characteristics, and the shape (cross-sectional shape) of the reflective surface of the reflective light guide. Optimal design is achieved by adjusting the inclination of the reflective surface and the surface roughness of the reflective surface.

The shape of the reflective surface provided on the surface of the reflective light guide 504 is as shown in FIG. Optimize the tilt, area, height, and pitch of the reflective surface according to the distance. In addition, by dividing the area serving as the same reflective surface (that is, the surface facing the polarization conversion element) into polyhedrons, the light intensity distribution of the light beam incident on the liquid crystal display panel 11 can be set to a desired value (optimal can be converted into

Similar to the reflective light guide described in FIG. 27B, the reflective surface provided on the reflective light guide has a configuration in which one surface (the area where light is reflected) has a shape with multiple inclinations (see FIG. In the example of No. 29, the reflected light can be adjusted with higher precision by dividing the XY plane into 14 parts and configuring them with different inclined surfaces. 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 a direction other than the desired direction (direction toward the liquid crystal display panel 11). can be prevented from occurring.

Further, the units 503 arranged on the left and right sides of the reflective light guide 504 in FIG. 29 may be replaced with the light source device in FIG. 27. That is, a plurality of light source devices (substrate 102, reflector 300, LED 14, etc.) shown in FIG. 27 are prepared, and the plurality of light source devices are connected to each other as shown in FIGS. 29(a), (b), and (c). It is also possible to have a configuration in which they are placed at opposing positions.

FIG. 30 is a cross-sectional view showing an example of the shape of the diffusion plate 206. As described above, the diverging light output from the LED is converted into substantially parallel light by the reflector 300 or the collimator 18, converted into a specific polarized light by the polarization conversion element 21, and then reflected by the light guide. Then, the light beam reflected by the light guide passes through the flat part of the incident surface of the diffuser 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).

Further, among the light emitted from the polarization conversion element 21 , a diverging luminous flux is totally reflected on the slope of a protrusion having a slope 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 on the slope of the projection of the diffuser plate 206, the angle of the slope of the projection is changed based on the distance from the polarization conversion element 21. When 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 close to the polarization conversion element 21 or the side close to the LED is α', α is smaller than α' (α<α'). With such a setting, it becomes possible to effectively utilize the polarized light flux.

<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. One example is to become That is, by optimizing the shape of the lenticular lens, the emission characteristics of the image light (hereinafter also referred to as "image light flux") emitted from the liquid crystal display panel 11 in one direction can be adjusted.

Alternatively or additionally, the 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, the emission characteristics of the image light flux emitted from the image display device 1 in the X-axis and Y-axis directions can be adjusted, and as a result, desired diffusion characteristics can be obtained. It is possible to obtain a video display device having the following.

The effect of the lenticular lens will be explained. As described above, when a lenticular lens with an optimized lens shape is used, the following effects can be obtained. That is, the output 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 windshield 105 to achieve a suitable A spatially floating image can be obtained.

As a further configuration example, a sheet may be used in which a combination of two lenticular lenses is arranged at a position through which the image light emitted from the image display device 1 passes, or a sheet in which a microlens array is arranged in a matrix to adjust the diffusion characteristics. may be provided. By configuring the optical system like this, the brightness (relative brightness) of the image light in the X-axis and Y-axis directions can be adjusted to the reflection angle of the image light (with the case of reflection in the vertical direction as the standard (0 degrees)). reflection angle).

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

Therefore, according to this embodiment, the image light has a narrow diffusion angle (high straightness) and has only a specific polarization component, like image light from a surface-emitting laser image source, and the image display device according to the prior art It is possible to suppress the ghost image that would occur in the retroreflective member when using the retroreflection member, and to make adjustments so that the spatially floating image due to retroreflection can be efficiently delivered to the viewer's eyes.

In addition, the above-described light source device allows the X-axis It is possible to provide a directional characteristic with a significantly narrow angle in both the direction and the Y-axis direction. In this embodiment, by providing such a narrow-angle directivity characteristic, it is possible to realize an image display device that emits a nearly parallel image light beam in a specific direction and emits light of a specific polarization. .

FIG. 21 shows an example of the characteristics of the lenticular lens employed in this example. This example particularly shows the characteristics in the X direction (vertical direction) with respect to the Z axis, and the characteristic O is that the peak of the light emission direction is at an angle of around 30 degrees upward from the vertical direction (0 degrees). , and exhibits vertically symmetrical brightness characteristics. Furthermore, the plot curves of characteristic A and characteristic B shown in the graph of FIG. 21 further show an example of a characteristic in which the brightness (relative brightness) is increased by focusing the image light above the peak brightness around 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 angle where the inclination (angle θ) from the Z axis to the X direction exceeds 30 degrees (θ > 30 degrees) In the region, the brightness (relative brightness) of light decreases rapidly.

That is, according to the optical system including the above-mentioned lenticular lens, when the image light flux from the image display device 1 is made to enter the retroreflective member 2, the output angle and field of view of the image light aligned at an included 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, the degree of freedom regarding the image formation position of the spatially floating image that is reflected or transmitted through the window glass 105 and formed at a desired position can be greatly improved. As a result, it becomes possible to efficiently reach the eyes of a viewer outdoors or indoors as light with a narrow diffusion angle (high straightness) and only a specific polarization component. According to this, even if the intensity (luminance) of the image light from the image display device 1 is reduced, the viewer can accurately recognize the image light and obtain information. In other words, by reducing the output of the video display device 1, it is possible to realize an information display system with low power consumption.

Various embodiments and examples (ie, specific examples) to which the present invention is applied have been described above in detail. On the other hand, the present invention is not limited to the embodiment (specific example) described above, and includes various modifications. For example, in the embodiments described above, the entire system is explained in detail in order to explain the present invention in an easy-to-understand manner, and the system is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of each embodiment with other configurations.

The light source device described above is not limited to a floating image display device, but can also be applied to information display devices such as a HUD, a tablet, a digital signage, and the like.

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

Further, in the technology according to the embodiment described above, by reducing the divergence angle of the emitted image light and aligning it with a specific polarization, only the normal reflected light can be efficiently reflected by the retroreflective member. , it is possible to obtain bright and clear spatial floating images with high light utilization efficiency. According to the technology according to the present embodiment, it is possible to provide a contactless user interface with excellent usability and which can significantly reduce power consumption. According to the present invention, which provides such technology, the Sustainable Development Goals (SDGs) advocated by the United Nations, ``9 Create a foundation for industry and technological innovation'' and ``11 Create sustainable cities'', can be achieved. Contribute to

Furthermore, the technique according to the embodiment described above makes it possible to form a spatially floating image using highly directional (straight-travelling) image light. With the technology according to this embodiment, even when displaying images that require high security such as at bank ATMs or ticket vending machines at stations, or when displaying highly confidential images that should be kept secret from the person directly facing the user, the technology can be used to display highly directional images. By displaying the image light, it is possible to provide a non-contact user interface in which there is little risk that the floating image will be looked into by anyone other than the user. By providing the above-mentioned technology, the present invention contributes to the Sustainable Development Goals (SDGs) advocated by the United Nations, "11: Creating livable cities."

DESCRIPTION OF SYMBOLS 1... Image display device, 2... Retroreflection member, 3... Spatial image (spatial floating image), 105... Wind glass, 100... Transmissive plate, 101... Polarization separation member, 12... Absorption type polarizing plate, 13... Light source device , 54... Light direction conversion panel, 151... Retroreflection member, 102, 202... LED board, 203... Light guide, 205... Reflection sheet, 271... Reflection plate, 206, 270... Retardation plate, 300... Space 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, reflective surface... 307, sub-reflector... 308, 310, 81... optical element, polarization conversion element... 501, unit... 503, light shielding wall... 507, 401, 402... light shielding plate, 320... base material

Claims (24)

A light source device,
a light source and
a reflector that reflects light from the light source;
A light guide that guides the light from the reflector,
The light source device includes a light shielding plate disposed between the reflector and the light guide,
The light shielding plate has a plurality of light shielding portions arranged to face each other so as to sandwich the light flux traveling from the reflector to the light guide with respect to the traveling direction of the light flux, and the light flux passes through the light flux passing through the light guide member . It is arranged so as to pass through an area sandwiched between multiple light-shielding parts ,
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 on the reflector side,
Light source device. The light source device according to claim 1,
The light shielding plate is arranged on a plane perpendicular to the emission direction of the light beam reflected by the reflector.
Light source device. The light source device according to claim 1,
The light source is a planar light source,
The reflective surface of the reflector has a shape that causes a divergent light beam from the plane of the light source in the shape of a plane to be reflected by the reflector and then emitted as a parallel light beam,
The emission direction of the light beam reflected by the reflective surface of the reflector is a direction perpendicular to the optical axis of the planar light source that is perpendicular to the plane.
Light source device. The light source device according to claim 1 ,
The reflective surface of the reflector is configured to reflect light from the light source, and 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 a first direction;
There are a plurality of light sources, and the plurality of light sources are arranged in a line in a second direction,
In a third direction that is perpendicular to the first direction and the second direction, the light shielding plate extends longer than the end of the polarization conversion element.
Light source device. The light source device according to claim 1,
guiding light toward a display panel by reflection on a reflective surface of the light guide;
A space is provided between the reflective surface of the light guide and the display panel, and natural cooling is performed in the space.
Light source device. The light source device according to claim 1,
The reflector is made of plastic material, glass material or metal material,
Light source device. The light source device according to claim 1,
comprising a diffusion plate that diffuses light from the light guide,
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 diffuser plate from the light guide are substantially parallel.
Light source device. The light source device according to claim 7 ,
There are multiple light sources,
The light sources are arranged in a line in a direction parallel to a side of the diffuser plate on the reflector side among the plurality of sides of the diffuser plate.
Light source device. The light source device according to claim 1,
a polarization conversion element that aligns the light from the light source with polarization in a specific direction;
a diffusion plate that diffuses light from the light guide;
comprising a side wall arranged to sandwich a space between the light guide and the diffuser plate,
The light exit surface of the polarization conversion element faces a space surrounded by the side wall, the light guide, the diffusion plate, and the polarization conversion element.
Light source device. The light source device according to claim 9 ,
the side wall has a vent;
Light source device. The light source device according to claim 9 ,
A surface of the side wall that is in contact with the space is a reflective surface,
Light source device. The light source device according to claim 9 ,
There are multiple light sources,
The light sources are arranged in a line in a direction parallel to a side of the diffuser plate on the reflector side among the plurality of sides of the diffuser plate.
Light source device. A light source device,
A light source in the shape of a plane,
a reflector that reflects light from the light source;
A light guide that guides the light from the reflector,
The light source device includes a light shielding plate disposed between the reflector and the light guide,
The light shielding plate has a plurality of light shielding portions arranged to face each other so as to sandwich the light flux traveling from the reflector to the light guide with respect to the traveling direction of the light flux, and the light flux passes through the light flux passing through the light guide member . It is arranged so as to pass through an area sandwiched between multiple light-shielding parts ,
The light reflected at the first position of the reflective surface of the reflector is reflected at a second position of the reflective surface of the light guide in a direction perpendicular to the plane of the light source, and the first position is different from the first position. The light reflected at a third position of the reflective surface of the reflector, which is a different position in the emission direction of the light flux reflected by the reflector, is defined as the second position, which is a different position in the emission direction of the light flux reflected by the reflector. There is a state in which the light is reflected in a direction perpendicular to the plane of the light source at a fourth position of the reflective surface of the light guide, which is a different position;
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 on the reflector side,
Light source device. The light source device according to claim 13 ,
The light shielding plate is arranged on a plane perpendicular to the emission direction of the light beam reflected by the reflector.
Light source device. The light source device according to claim 13 ,
The light source is a planar light source,
The reflective surface of the reflector has a shape that causes a divergent light beam from the plane of the light source in the shape of a plane to be reflected by the reflector and then emitted as a parallel light beam,
The emission direction of the light beam reflected by the reflective surface of the reflector is a direction perpendicular to the optical axis of the planar light source that is perpendicular to the plane.
Light source device. The light source device according to claim 13 ,
The reflective surface of the reflector is configured to reflect light from the light source, and 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 a first direction;
There are a plurality of light sources, and the plurality of light sources are arranged in a line in a second direction.
Light source device. The light source device according to claim 13 ,
guiding light toward a display panel by reflection on a reflective surface of the light guide;
A space is provided between the reflective surface of the light guide and the display panel, and natural cooling is performed in the space.
Light source device. The light source device according to claim 13 ,
The reflector is made of plastic material, glass material or metal material,
Light source device. The light source device according to claim 13 ,
comprising a diffusion plate that diffuses light from the light guide,
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 diffuser plate from the light guide are substantially parallel.
Light source device. The light source device according to claim 19 ,
There are multiple light sources,
The light sources are arranged in a line in a direction parallel to a side of the diffuser plate on the reflector side among the plurality of sides of the diffuser plate.
Light source device. The light source device according to claim 13 ,
a polarization conversion element that aligns the light from the light source with polarization in a specific direction;
a diffusion plate that diffuses light from the light guide;
comprising a side wall arranged to sandwich a space between the light guide and the diffuser plate,
The light exit surface of the polarization conversion element faces a space surrounded by the side wall, the light guide, the diffusion plate, and the polarization conversion element.
Light source device. The light source device according to claim 21 ,
the side wall has a vent;
Light source device. The light source device according to claim 21 ,
A surface of the side wall that is in contact with the space is a reflective surface,
Light source device. The light source device according to claim 21 ,
There are multiple light sources,
The light sources are arranged in a line in a direction parallel to a side of the diffuser plate on the reflector side among the plurality of sides of the diffuser plate.
Light source device.

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