WO2022185927A1

WO2022185927A1 - Spatial floating image display device

Info

Publication number: WO2022185927A1
Application number: PCT/JP2022/006269
Authority: WO
Inventors: 浩二平田; 浩司藤田; 寿紀杉山
Original assignee: マクセル株式会社
Priority date: 2021-03-05
Filing date: 2022-02-16
Publication date: 2022-09-09
Also published as: JP2022135253A

Abstract

The purpose of the present invention is to obtain a spatial floating image display device that displays a pseudo-stereoscopic spatial floating image.　According to the technology in the present disclosure, the imaging point of a retroreflective image (3a) is offset in the depth direction with respect to a display plane by, for example, the surface shape of a reflective mirror (300a) constituting the spatial floating image device, thus forming a pseudo-stereoscopic image. Furthermore, signal components corresponding to shades or shadows are formed in a display image and superimposed on an original signal to accentuate the effect of the stereoscopic display.

Description

Spatial floating image display device

The present invention relates to the technology of a spatially floating image display device that displays a spatially floating image to the driver of an automobile, train, aircraft, etc. (also referred to as a "vehicle"), and allows the driver to observe the image of the spatially floating image as a real image. The present invention relates to a technology of a spatially floating image display device using such an optical system.

As a video display device that projects video light onto the windshield or combiner of a vehicle to form a virtual image, and displays traffic information such as vehicle route information and traffic congestion information, and vehicle information such as fuel level and cooling water temperature. , a so-called head-up display (HUD: Head-Up-Display) device is known. Japanese Patent Laying-Open No. 2015-194707 (Patent Document 1) discloses an example of a HUD device.

JP 2015-194707 A Japanese Patent No. 4788882

In this type of image display device, while it is desirable to expand the area where the driver can view the virtual image, it is also an important performance factor that the virtual image has high resolution and high visibility. In addition, the HUD makes the position where the virtual image is established farther from the driver's viewpoint in order to reduce the movement of the driver's viewpoint, and can display augmented reality (AR) in which the virtual image is superimposed on the real scene that the driver is visually recognizing. There is Such a HUD has the problem that the set of devices and systems becomes large in order to make the virtual image generation position farther and to achieve high magnification.

Furthermore, the above-mentioned HUD device uses an optical system including a concave mirror (having the action of a convex lens) to provide a virtual image of the image displayed on the image display device such as a liquid crystal display as an enlarged image to the driver. As shown in FIGS. 2A and 2B, the windshield 6 of an automobile has a radius of curvature Rv in the vertical direction and a radius of curvature Rh in the horizontal direction different from each other, and generally has a relationship of Rh>Rv. For this reason, in the conventional HUD shown in FIG. 23, if the windshield 6 is regarded as the reflecting surface, the reflecting surface is the toroidal surface of the concave mirror 401 . Therefore, in the conventional HUD, the shape of the concave mirror 401 is designed to correct the virtual image magnification due to the shape of the windshield 6 . That is, the shape of the concave mirror 401 has different average curvature radii in the horizontal and vertical directions so as to correct the difference between the vertical curvature radius Rh and the horizontal curvature radius Rv of the windshield 6 .

As described above, since the windshield is used as the final reflecting surface, vehicles such as automobiles that emphasize design have the following problems. (1) Design changes occur until just before mass production, making it difficult to determine design specifications. (2) Since each car has a different design, it is difficult to apply the HUD device of the same specification to other car models. Due to the difficulty of this development, it has been a hindrance to the expansion of the HUD market. In addition, external light such as sunlight entering the inside of the HUD device at a specific angle through the windshield may be condensed by the concave mirror 401 and enter the liquid crystal display panel 404 . In that case, it is necessary to optimize the reflection characteristics of the concave mirror 401 and provide an optical element 403 that reflects a specific polarized wave so as not to damage the output-side polarizing plate of the liquid crystal display panel 404 .
SUMMARY OF THE INVENTION An object of the present invention is to provide a suitable spatial floating image display device in consideration of the above problems.

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above problems. To give an example, a floating image display device in space includes a liquid crystal display panel as an image source (image display device) and a polarization direction specific to the image source. and a light source device for supplying light of A light source device includes a point-like or planar light source, optical means for reducing the divergence angle of light from the light source, and a light guide having a reflective surface that propagates to an image source. The light guide is arranged to face the image source, has a reflecting surface inside or on the surface for reflecting the light from the light source toward the image source, and propagates the light to the image source. The video source modulates the light intensity in accordance with the video signal. The light source device adjusts part or all of the divergence angle of the light flux incident on the image source from the light source by the shape and surface roughness of the reflecting surface provided on the light source device. A spatially floating image display device forms a spatially floating image in the air by reflecting an image light flux having a narrow divergence angle from an image source with a retroreflective optical member. The spatially floating image display device may be provided with polarization conversion means for aligning the light from the light source into a specific direction of polarization in order to improve the contrast performance of the spatially floating image.

Furthermore, in order to reduce the generation of ghost images in spatially floating images, as described above, the image light from the image source has narrow-angle divergence characteristics, and an unnecessary light beam is formed between the image source and the retroreflective optical member. By providing a light shielding member that shields light and considering the layout of the optical system so that external light does not enter the retroreflective optical member, the generation of ghosts is reduced. In order to reduce the amount of blurring in the image floating in space, the surface roughness of the reflective surface of the retroreflective optical member is reduced to a predetermined value or less per unit length. improve. Further, the spatially floating image display device is provided with a mechanism capable of changing the distance between the image source and the retroreflective optical member, thereby enabling the display position of the spatially floating image to be changed.

In addition, in order to reproduce the spatially floating image as a pseudo-stereoscopic image, a reflecting optical member is arranged between the retroreflecting optical member and the retroreflecting image and serves also as an optical path folding means, and this reflecting optical member has an optical refractive power. Information in the depth direction is added so that the aggregate of image forming points of the spatially floating image has a convex shape facing the viewer. At this time, by slanting the optical members having optical refractive power, the effect of external light on the space-floating image reproduced as a pseudo-stereoscopic image is reduced, and for example, shadows can be emphasized by image processing. The three-dimensional effect is further emphasized.

According to the present invention, it is possible to provide a suitable spatial floating image display device.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a diagram showing an example of a usage pattern of a spatially floating image display device according to an embodiment of the present invention; FIG. FIG. 10 is a top view of a vehicle equipped with a spatially floating imaging device, and an explanatory diagram for explaining the difference in radius of curvature of the windshield; FIG. 10 is a top view of a vehicle equipped with a spatially floating imaging device, and an explanatory diagram for explaining the difference in radius of curvature of the windshield; 1 is a diagram showing a first embodiment of a configuration of a main part when a spatially floating image display device is installed in an automobile; FIG. FIG. 10 is a diagram showing a second embodiment of the configuration of the main parts when the spatially floating image display device is installed in an automobile; 1A and 1B are diagrams showing an example of a configuration of a main part and a configuration of a retroreflective optical part for explaining the principle of a floating image display device according to an embodiment of the present invention; FIG. 1A and 1B are diagrams showing an example of a configuration of a main part and a configuration of a retroreflective optical part for explaining the principle of a floating image display device according to an embodiment of the present invention; FIG. It is a figure which shows the problem of a spatial floating image display apparatus. FIG. 5 is a characteristic diagram showing the relationship between the surface roughness of a retroreflective optical member and the blur amount of a retroreflected image; FIG. 4 is a diagram showing another embodiment of the configuration of the main parts of the spatial floating image display device according to one embodiment of the present invention; FIG. 4 is a diagram for explaining the principle of forming a spatially floating image in the spatially floating image display device according to an embodiment of the present invention; FIG. 4 is an explanatory diagram of forming a spatially floating image in the spatially floating image display device according to an embodiment of the present invention; 1 is a diagram showing the configuration of a spatially floating image display device according to an example; FIG. FIG. 10 is a diagram showing another configuration of the spatial floating image display device according to one embodiment; It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. It is a sectional view showing an example of concrete composition of a light source device. FIG. 4 is an explanatory diagram for explaining diffusion characteristics of a display device; FIG. 4 is an explanatory diagram for explaining diffusion characteristics of a display device; FIG. 4 is an explanatory diagram for explaining diffusion characteristics of a display device; FIG. 4 is an explanatory diagram for explaining diffusion characteristics of a display device; It is a sectional view showing an example of concrete composition of a light source device. It is a figure which shows an example of a concrete structure of a light source device. It is a figure which shows an example of a concrete structure of a light source device. It is a figure which shows an example of a concrete structure of a light source device. FIG. 4 is a characteristic diagram showing reflection characteristics of glass with respect to light incident angles due to differences in polarization components; FIG. 3 is a characteristic diagram showing spectral irradiance of sunlight; It is a figure which shows the principal part structure at the time of installing HUD of the former (comparative example) in a motor vehicle.

In conventional spatial floating image display devices, organic EL panels and liquid crystal display panels as high-resolution color display image sources are combined with retroreflective optical members. In this spatially floating image display device, as shown in FIG. 6, the image light emitted from the liquid crystal panel, which is the image light source, has a wide-angle diffusion characteristic and the retroreflective optical member is a hexahedron. In addition to the reflected light 6002, reflected light 6004 generated by the image light 6003 obliquely incident on the retroreflective optical member 2a causes a ghost image, which impairs the image quality of the floating image. Since the retroreflective optical member shown as an example of the prior art is a hexahedron, a plurality of ghost images from the first ghost image G1 to the sixth ghost image G6 (not shown) are generated in addition to the regular spatial floating image R1. Occur. As a result, the ghost image, which is the same space-floating image, is viewed by people other than the viewer, and there is a serious problem that the apparent resolution of the space-floating image is greatly reduced. Here, an example of a structure that achieves retroreflection by reflection from the hexahedron shown in FIG. 6 is shown. For the same reason, there is a problem that a ghost image is generated in an optical member that obtains a retroreflection image by at least two retroreflections. Although the hexahedron having the projection-shaped reflecting surfaces has been described above, it goes without saying that the same effect can be obtained with a hexahedron having reflecting surfaces that are concave with respect to the surroundings.

In addition, there is a configuration in which image light from a display device having a narrow-angle directional characteristic, which will be described later, is reflected by a retroreflective optical member, thereby obtaining a spatially floating image. According to experiments by the inventors, in the spatially floating image thus obtained, in addition to the ghost image described above, as shown in FIG. 7, blurring was visually recognized for each pixel of the liquid crystal display panel.
<Summary of Spatial Floating Image Display Device>

FIG. 1 is a schematic configuration diagram for explaining the superiority of the space-floating image display device according to the present embodiment when used for in-vehicle use. Here, as an example, a spatially floating image display device 1000 that obtains a spatially floating image without using the windshield 6 of an automobile will be described. The spatially floating image display device 1000 obtains a spatially floating image 220 in the interior space of the own vehicle at an eye point 8 (described in detail later) corresponding to the line of sight of the driver. As a result, a visual effect similar to that of forming a pseudo virtual image V1 in front of the vehicle can be obtained. The inventor confirmed this through experiments. A detailed description will be given below.

As shown in FIG. 1, when a spatially floating image 220 is viewed from an eye point 8, a conventional HUD is used to project a projected member 6 (in this embodiment, the inner surface of the windshield, i.e., the surface facing the driver inside the vehicle). The spatially floating image 220 (corresponding virtual image V1) can be superimposed on the real scene visually recognized by the driver, in the same manner as in the case of viewing the virtual image V1 reflected by the surface). The information displayed as the space floating image 220 includes, for example, vehicle information, foreground information captured by a camera (not shown) such as a surveillance camera or an around viewer, scenery around the vehicle before starting, a speedometer, and an engine. information such as a tachometer and remaining energy display.

In this embodiment, the floating image display device 1000 includes the image display device 4 that displays the image corresponding to the information and projects the corresponding image light, and the image displayed on the image display device 4 that reflects the image displayed in the space. and a retroreflective optical member 2100 (in other words, a retroreflective optical element) that forms a floating image 220 . The retroreflective optical member 2100 has a spatially movable structure (shown as vertically movable in the drawing), and by moving it up and down, the position where the spatially floating image 220 is formed can be moved diagonally up and down ( can be moved up and down). As a result, the inclination angle θe changes by moving up and down the position where the spatially floating image 220 viewed by the driver from the eyebox (a predetermined space including the eyepoint 8) is formed. Thereby, an effect equivalent to changing the display position of the virtual image in the conventional HUD can be obtained. In addition, by detecting the movement of the driver's line of sight (eye point 8), for example, with a monitor camera (not shown) in the vehicle, the display position of the spatially floating image 220 can be adjusted vertically and horizontally according to the movement of the line of sight. can also be moved to

In this embodiment, the image light from the image display device 4 is once returned by a reflecting mirror (in other words, folding mirror) 2110 provided on the optical path between the image display device 4 and the retroreflective optical member 2100 . By moving the retroreflective optical member 2100 and changing the distance between the reflecting mirror 2110 and the retroreflective optical member 2100, the optical distance from the image display device 4 to the retroreflective optical member 2100 can be changed.

For example, by moving the retroreflective optical member 2100 downward in the drawing, the distance between the reflecting mirror 2110 and the retroreflective optical member 2100 can be lengthened. Then, the position of the space-floating image 220 obtained after being reflected by the retroreflective optical member 2100 can be set to a higher position in the vertical direction in the drawing, which is associated with the virtual image far away from the driver. Thereby, the position where the spatially floating image 220 is formed can be made higher than, for example, the upper surface (not shown) of the dashboard of the vehicle. On the other hand, by moving the retroreflective optical member 2100 upward in the drawing, the distance between the reflecting mirror 2110 and the retroreflective optical member 2100 can be shortened. As a result, the position where the floating image 220 is formed can be lowered.
<Specific Example 1 of Spatial Floating Image Display Device>

A first example of the spatially floating image display device for in-vehicle use according to the present invention will be described below with reference to FIG. In this embodiment, the space floating image display device 1000 is incorporated in the dashboard 48. FIG. A spatially floating image display device 1000 includes an image display device 4, a retroreflective optical member 2100, and the like. The image displayed on the image display device 4 is preferably displayed by emphasizing the shadow of the display image in order to emphasize the depth direction. A liquid crystal display panel is used which modulates the light supplied from the light source device 10 in accordance with a video signal and emits light of a specific polarized wave. An image of a specific polarized wave (here, S polarized wave) modulated by this liquid crystal display panel is transmitted through a beam splitter or a reflective polarizing plate 2140 that transmits S polarized light and reflects P polarized light. , enters the reflection mirror 2110 and is reflected by the retroreflective optical member 2100 disposed on the bottom surface of the floating image display device 1000 to form the floating image 220 . A λ/4 plate 215 is provided on the image light incident surface of the retroreflective optical member 2100 . The S-polarized image light is incident on and reflected by the retroreflective optical member 2100, passes through the λ/4 plate 215 twice, and is thereby converted into P-polarized light. The P-polarized image light is reflected by a reflecting mirror 2110 , reflected by a beam splitter or a reflective polarizing plate 2140 , and reflected by a reflecting optical element 2120 provided above the floating image display device 1000 . If the shape of the reflecting surface of the reflecting optical element 2120 is, for example, convex toward the driver side, the spatially floating image is also curved in the depth direction at the periphery of the screen center, so that when viewed from the driver A spatially floating image (stereoscopic spatially floating image) to which information in the depth direction is artificially added can be obtained. At this time, as described above, it is preferable to emphasize shadows and display on the image display device 4 in order to emphasize the depth direction. Furthermore, if the displayed image is a person or the like, adding a shadow portion emphasizes the three-dimensional spatial floating image. The image light forming the spatially floating image described above is emitted from the opening 41 provided in the dashboard 48, and the spatially floating image 220 is obtained at the position shown in the drawing (the position in front of the windshield 6 in the vehicle). be able to. The imaging position of the spatial floating image obtained at this time is formed on the line segment connecting the reflective optical element 2120 and the viewpoint, and the image is formed above the upper end of the reflective optical element 2120, which is different from the conventional AR-HUD. Similarly, it is possible to superimpose a three-dimensional spatial floating image as a real image on the real scene viewed by the driver while driving. At this time, unlike conventional HUDs, the windshield is not used as an optical system, so even if the radius of curvature or inclination of the windshield changes depending on the design of the car, it will not be affected, and the space is highly adaptable to different vehicle types. It becomes a floating image display device.

The reflective optical element 2120 can use a reflective film obtained by coating or depositing a metal reflective film with a stepper, a beam splitter that selectively reflects a specific polarized wave, or a reflective polarizing plate. This has the following effects. When the angle of incidence of the outside light component such as sunlight incident from the windshield 6 is large, as shown in FIG. 21, the reflectance of S-polarized light is high. Therefore, the P-polarized light component enters the interior of the vehicle. Reflective optical element 2120 selectively reflects this P-polarized component. Therefore, optical components behind the reflective optical element 2120 (lower side in the figure) (components in the housing of the floating image display device 1000, image display device 4 (liquid crystal display panel), beam splitter or reflective polarization External light does not enter the plate 2140, the retroreflective optical member 2100, etc.). As a result, the reliability of the optical parts, the image display device 4 (liquid crystal display panel), the polarizing plate (not shown) arranged on the image light emitting side of the liquid crystal display panel, and the like is not impaired.

Furthermore, the reflective optical element 2120 is even better if it has a characteristic of reflecting light with a wavelength of 800 nm or more and ultraviolet rays, which contribute to temperature rise, among the spectral radiant energies of the sunlight shown in FIG. 22 . Also in this embodiment, as in the example shown in FIG. 1, the retroreflective optical member 2100 is configured to be movable in the vertical direction in the drawing, so that the position where the floating image 220 is formed can be moved vertically. can move. As a result, the depression angle of the spatially floating image 220 seen from the driver's eye point 8 changes, and the image display distance and size of the spatially floating image 220 are changed in a pseudo manner with respect to the actual scene visually recognized by the driver. be able to. Furthermore, in this embodiment as well, a camera (not shown) is provided to detect the line of sight of the driver, and by tracking the line of sight of the driver, the display position of the spatially floating image 220 is interlocked with the position of the line of sight. may Also, the image displayed as the space floating image 220 at this time should preferably be alert information that matches the actual scenery that the driver is seeing, thereby realizing attention while driving. In the example shown in FIG. 3, if the reflecting mirror 2120 arranged at the final position on the optical path of the device is removed, part or all of the image light passes through the windshield 6 and A floating image 60 can be displayed on the inner surface of the vehicle 6 or at a position above the windshield 6 outside the vehicle.
<Specific Example 2 of Spatial Floating Image Display Device>

A second example of the spatially floating image display device for in-vehicle use according to the present invention will be described below with reference to FIG. As in the first example, the video display device 4 in the second example is a liquid crystal display panel that modulates the light supplied from the light source device 10 in accordance with the video signal and emits it as light of a specific polarized wave. use. An image of a specific polarized wave (here, S-polarized wave) modulated by the liquid crystal display panel is transmitted through a beam splitter or a reflective polarizing plate 2140 that transmits S-polarized light and reflects P-polarized light. It is reflected by the retroreflective optical member 2100 to form a spatially floating image 220 . A λ/4 plate 215 is provided on the image light incident surface of the retroreflective optical member 2100 . The S-polarized image light enters the retroreflective optical member 2100 and is reflected, so that it passes through the λ/4 plate 215 twice and is converted into P-polarized light. The P-polarized image light is reflected by the beam splitter or reflective polarizing plate 2140, reflected by the reflecting mirror 2120 provided above, and reflected by the reflecting optical element 2120 provided above the spatial floating image display device 1000. be. If the shape of the reflecting surface of the reflecting optical element 2120 is, for example, convex toward the driver side, the spatially floating image is also curved in the depth direction at the periphery of the screen center, so that when viewed from the driver A three-dimensional spatial floating image to which information in the depth direction is artificially added can be obtained. At this time, as described above, it is preferable to emphasize shadows and display on the image display device 4 in order to emphasize the depth direction. Furthermore, if the displayed image is a person or the like, adding a shadow portion emphasizes the three-dimensional spatial floating image. The image light that forms the spatially floating image described above is emitted from the opening 41 provided in the dashboard 48 . As a result, a spatially floating image 220 can be obtained at a predetermined position. The imaging position of the spatially floating image obtained at this time is formed on the line segment connecting the reflective optical element 2120 and the viewpoint. An image can be superimposed as a real image on a part of the real scene viewed by a person while driving. At this time, unlike conventional HUDs, the windshield is not used as an optical system, so even if the radius of curvature or inclination of the windshield changes depending on the design of the car, it will not be affected, and the space is highly adaptable to different vehicle types. It becomes a floating image display device.

The same reflective optical element 2120 as in the first example can be used. As a result, the reflective optical element 2120 selectively reflects the P-polarized component entering the interior of the vehicle as described above (FIG. 21). Therefore, external light does not enter the optical parts behind the reflecting mirror 2120, and the reliability of the optical parts, the liquid crystal display panel 4 and the like is not impaired. Furthermore, the characteristics of the reflective optical element 2120 are even better if they are the same characteristics as in the first example (FIG. 22). Also, as in the example shown in FIG. 1, the retroreflective optical member 2100 is configured to be movable in the horizontal direction in the drawing. As a result, in this embodiment, the position where the three-dimensional spatial floating image 220 is formed can be moved diagonally up and down. As a result, the depression angle of the space floating image 220 visible from the driver's eye point 8 changes, and the image display distance and size of the space floating image 220 which is pseudo-stereoscopic with respect to the actual scene visually recognized by the driver changes. can be changed.

According to the embodiment described above, for example, a high-resolution image is displayed in a floating state on the extension line of the opening 41 on the dashboard 48 (for example, the optical path of the light reflected by the reflecting optical element 2120). It can be displayed as a visible stereoscopic spatial floating image 220 . At this time, in this embodiment, the divergence angle of the image light emitted from the opening 41 of the spatially floating image display device 1000 is made small, ie, an acute angle, and is arranged to have a specific polarization. As a result, only regular reflected light is efficiently reflected to the retroreflective optical member 2100 . For this reason, according to the embodiment, the light utilization efficiency is high, and the ghost image that occurs in addition to the above-mentioned main space floating image, which has been a problem in the conventional retroreflection method, can be suppressed, and clear space floating can be obtained. You can get pictures. Also, with the configuration including the light source (light source device 10) of the present embodiment, it is possible to provide a novel and highly usable spatial floating image display device capable of significantly reducing power consumption. Further, as described above, it is possible to provide a spatially floating image display device for a vehicle capable of displaying a so-called unidirectional spatially floating image that can be viewed inside or outside the vehicle through the windshield 6 of the vehicle. .

The configuration of the spatially floating image display device according to this embodiment will be described more specifically with reference to FIGS. 5A and 5B. As shown in FIG. 5A, the oblique direction of the transparent member 100 such as glass (the direction of the plane of the transparent member 100 as shown in the figure and the predetermined direction with an angle to the direction perpendicular to it. The direction of the axis 5001) is provided with the display device 1 that diverges image light of a specific polarized wave to a narrow angle. The display device 1 includes a liquid crystal display panel 11 which is a video source and emits video light, and a light source device 13 (in other words, a backlight) which generates specific polarized light having narrow-angle diffusion characteristics.

The specific polarized image light from the display device 1 is reflected by the polarization separation member 101 having a film that selectively reflects the specific polarized image light provided on the transparent member 100 , and the reflected light is reflected on the optical axis 5002 . incident on the retroreflective optical member 2 in a direction. In the drawing, the polarized light separation member 101 is formed in a sheet shape and adhered to the surface of the transparent member 100 . A λ/4 plate 2 b is provided on the image light incident surface of the retroreflective optical member 2 . The image light is passed through the λ/4 plate 2b twice, once upon entering the retroreflective optical member 2 and once upon exiting, thereby undergoing polarization conversion from the specific polarized wave to the other polarized wave. Here, the polarization separating member 101 that selectively reflects the image light of the specific polarized wave has the property of transmitting the polarized light of the other polarized wave that has undergone polarization conversion. Therefore, in the direction of the optical axis 5002 , the image light of the specific polarized wave after the polarization conversion is transmitted through the polarization separation member 101 . The image light transmitted through the polarization separation member 101 forms a space floating image 220 which is a real image at a predetermined position outside the transparent member 100 in the direction of the optical axis 5003 .

The light that forms the spatially floating image 220 is a set of light rays that converge from the retroreflective optical member 2 to the optical image of the spatially floating image 220, and these rays continue to pass through the optical image of the spatially floating image 220. Go straight. Therefore, the spatially floating image 220 is an image having high directivity, unlike diffuse image light formed on a screen by a general projector or the like. Therefore, in the configuration of FIGS. 5A and 5B, when the user (corresponding eye point) views the spatial floating image 220 from the direction of the arrow A, the spatial floating image 220 is viewed as a suitable bright image. When another person views from the direction of arrow B different from arrow A, the spatial floating image 220 cannot be viewed as an image at all. This highly directional characteristic is useful for systems that display video information that only the driver (user with an eyepoint position corresponding to direction A) needs, and systems that display video information required by other people outside the vehicle (direction B) facing the driver. It is very suitable for use in a system for displaying highly confidential images that should be kept confidential from other people in the vehicle, such as a person who has an eye point corresponding to the vehicle.

Depending on the performance of the retroreflective optical member 2, the polarization axes of the reflected image light may become uneven. In this case, part of the image light whose polarization axes are not aligned is reflected by the polarization separation member 101 described above and returns to the display device 1 . This light may be re-reflected on the image display surface of the liquid crystal display panel 11 constituting the display device 1 to generate a ghost image as described above and degrade the image quality of the spatially floating image 220 . Therefore, in this embodiment, the image display surface of the display device 1 is provided with the absorptive polarizing plate 12 . Image light emitted from the display device 1 is transmitted through the absorptive polarizing plate 12 , and reflected light returning from the polarization separation member 101 is absorbed by the absorptive polarizing plate 12 . As a result, the re-reflection and the like can be suppressed, and deterioration in image quality due to a ghost image of the spatially floating image 220 can be prevented.

For the polarization separation member 101 described above, for example, a reflective polarizing plate, a metal multilayer film that reflects a specific polarized wave, or the like can be used.

Next, FIG. 5B shows the surface shape of the retroreflective optical member manufactured by Nippon Carbide Industry Co., Ltd. used in this study as a typical retroreflective optical member 2 . This retroreflective optical member has hexagonal prisms regularly arranged in the plane. Light rays incident on the inside of the regularly arranged hexagonal prisms are reflected by the walls and bottom surfaces of the hexagonal prisms and emitted as retroreflected light in a direction corresponding to the incident light, thereby forming a spatial floating image 220 shown in FIG. 5A. to form a normal image R1 (an image formed at a predetermined position). In the retroreflective optical member, a reflective surface is provided on the bottom surface so that the hexagonal prism in the figure becomes a surface in contact with the air, a hexagonal corner surface is formed on the upper part of the reflective surface, the hexahedron and the hexagonal prism are hollow, and the remaining The same effect can be obtained even if the portion is filled with resin.

On the other hand, as shown in FIG. 6, of the image light from the display device 1, depending on the image light obliquely incident on the retroreflective optical member, a ghost image is formed separately from the normal image R1. The spatially floating image display device of the present invention displays a spatially floating image, which is a real image, based on the image displayed on the display device 1 . The resolution of this spatially floating image largely depends on the resolution of the liquid crystal display panel 11 as well as the external shape D and the pitch P of the retroreflective optical member 2 (hexagonal prism) shown in FIG. 5B. For example, when using a 7-inch WUXGA (1920×1200 pixels) liquid crystal display panel, even if one pixel (one triplet) is about 80 μm, for example, the diameter D of the retroreflective optical member 2 (hexagonal prism) is 240 μm. If the pitch P is 300 μm, one pixel of the spatial floating image corresponds to 300 μm. Therefore, the effective resolution of the spatially floating image is reduced to about ⅓.

Therefore, in order to make the resolution of the spatially floating image equal to that of the display device 1, it is desired that the diameter D and the pitch P of the retroreflective optical member 2 (hexagonal prism) be close to one pixel of the liquid crystal display panel 11. . On the other hand, in order to suppress the occurrence of moiré caused by the retroreflective optical member 2 and the pixels of the liquid crystal display panel 11, it is preferable to set the pitch ratios of the respective elements out of integral multiples of one pixel. Moreover, it is preferable that the retroreflective optical member 2 is arranged so that no one side of the retroreflective optical member 2 overlaps any one side of one pixel of the liquid crystal display panel 11 .

Furthermore, as shown in FIG. 6, when external light 6000 enters the retroreflective optical member 2 from an oblique direction, it is reflected by the surfaces (

hexagonal prisms

2a, 2b, 2c, etc.) of the retroreflective optical member 2, and is reflected in various directions. A ghost image is generated, and the image quality of the space floating image is greatly reduced. The inventor obtained by experiments the relationship between the blur amount l of the image of the spatially floating image and the pixel size L that is permissible for improving the image quality and visibility of the spatially floating image. At that time, the inventor created a display device 1 by combining a liquid crystal display panel with a pixel pitch of 40 μm and a light source device having a characteristic of a narrow divergence angle (for example, a divergence angle of 15°) of the present embodiment. asked for a relationship.

It has been found that the amount of blur l that deteriorates visibility is preferably 40% or less of the pixel size, and is almost inconspicuous if it is 15% or less. The surface roughness of the reflective surface (surface roughness 6010 of the retroreflecting surface in FIG. 6) for which the amount of blur l at this time is an allowable amount has an average roughness of 160 nm or less in the range of the measurement distance of 40 μm, and is less conspicuous. It has been found that the surface roughness of the reflecting surface is desirably 120 nm or less in order to obtain the blur amount l. Therefore, it is desirable to reduce the surface roughness of the retroreflective optical member described above, and to reduce the surface roughness including the reflecting film forming the reflecting surface and its protective film to the above-described value or less.

On the other hand, in order to manufacture retroreflective optical members at low cost, it is preferable to use a roll press method for molding. Specifically, it is a method of aligning the retroreflecting portions (hexagonal prisms in FIG. 6) and shaping them on the film. In this method, the reverse shape of the shape to be shaped is formed on the surface of the roll, UV curable resin is applied on the base material for fixing, and it is passed between the rolls to shape the required shape, and the UV to obtain a retroreflective optical member 2 having a desired shape.

The display device 1 of the present embodiment shown in FIGS. 5A and 5B includes a liquid crystal display panel 11 and a light source device 13 that generates specific polarized light having narrow-angle diffusion characteristics, which will be described later in detail. It is possible to reduce the possibility that the image light is incident obliquely (FIG. 6) on the retroreflective optical member 2 thus formed. As a result, even if a ghost image occurs, the luminance is low, resulting in a structurally excellent device.
<Example 3 of spatial floating image display device>

Next, another example of the spatial floating image display device for in-vehicle use of the present invention will be described with reference to FIGS. 8A, 8B, 8C, 9A, and 9B.

FIG. 8A is a diagram showing another example of the main configuration of the spatial floating image display device according to one embodiment of the present invention. FIG. 8B is a diagram for explaining the principle of spatial floating image formation of the spatial floating image display device according to one embodiment of the present invention. FIG. 8C is an explanatory diagram of forming a spatially floating image in the spatially floating image display device according to one embodiment of the present invention. FIG. 9A is a diagram showing the configuration of a spatially floating image display device according to an example. FIG. 9B is a diagram showing another configuration of the spatially floating image display device according to one embodiment.

As shown in FIGS. 9A and 9B, the display device 1 includes a liquid crystal display panel 11 as an image display element, and a light source device 13 for generating specific polarized light having narrow-angle diffusion characteristics. be done. The liquid crystal display panel 11 is composed of a liquid crystal display panel selected within a range from a small screen size of about 3 inches to a large screen size exceeding 80 inches. For example, if the image light from the liquid crystal display panel 11 is P-polarized light, it passes through the polarization separating member 101 that transmits P-polarized light and travels toward the retroreflective optical member 2 . A λ/4 plate 21 is provided on the light incident surface of the retroreflective optical member 2, and the polarization conversion is performed by passing the image light twice, and the specific polarized wave (P polarized wave) is converted to the other polarized wave (S polarized wave). ). The other polarized wave (S polarized wave) is reflected by the polarization separation member 101, and when a reflecting mirror 300b (illustrated as a plane mirror in FIG. 8A) is provided outside the transparent member 100, As shown, a real plane image 3 (space floating image) is displayed. When a reflecting mirror 300a (illustrated as a convex mirror in FIG. 8A) is provided, a spatially floating image can be obtained by using a mirror having a convex surface (described as a convex surface in this embodiment) on the viewing side of the image. The image plane can be convex with respect to the viewer. FIG. 8B is a diagram showing image forming conditions of image forming points (convex surfaces) of spatially floating images (stereoscopic images) in the XZ plane and the XY plane, respectively.

Furthermore, as shown in FIG. 8C, the viewing direction of the viewer is recognized by the camera, and the shadow (shown in gray in FIG. 8C) produced when light is incident from this direction is superimposed on the video signal of the original image. The three-dimensional effect is emphasized by adding shadows to the images floating in space. Similarly, by folding back the luminous flux by the reflecting mirror 300a having a shape different from the flat surface described above, the imaging point of the spatially floating image can be moved in the depth direction according to the shape of the folding mirror, and shadows in the spatially floating image can be emphasized. By applying this image processing and adding a shadow portion to the displayed image, it is possible to display a pseudo-stereoscopic spatial floating image that emphasizes the three-dimensional effect. In FIGS. 8A, 9A, and 9B, P-polarized waves are indicated by solid lines and S-polarized waves by dashed lines. The image light from the liquid crystal display panel 11 may be S-polarized.

Furthermore, as shown in FIGS. 9A and 9B, as a configuration capable of rotating the polarization separation member 101 in the same manner as the reflection mirror 300, by rotating the reflection mirror 300 and the polarization separation member 101, the spatial floating image can be obtained. The orientation and position of 3 can be adjusted. The polarization splitting member 101 shown in FIG. 9B is rotated in the direction of rotation in the figure in order to reflect the specific polarized wave in a state inclined in a direction inclined with respect to the plane of the paper. can be moved forward and backward. By using a convex mirror as the reflecting mirror 300 shown in FIGS. 9A and 9B, a pseudo-stereoscopic spatial floating image is obtained as shown in FIG. It goes without saying that the orientation and position can be adjusted.

By tilting the reflecting mirror 300 within the YZ plane (see FIG. 8B), the amount of external light entering the retroreflective optical element via the reflecting mirror 300 can be reduced. As a result, the light intensity of the ghost image is also reduced. As a result, the image quality of the obtained stereoscopic spatial floating image is greatly improved. In order to reduce the amount of external light, a metal multilayer film is formed as the reflecting film of the reflecting mirror 300, and the characteristic is such that the reflectance of a specific polarized wave (S polarized wave in this embodiment) is 85% or more, and on the other hand, the P polarized wave has a reflectance of 85% or more. If the reflectance is set to 20% or less (the transmittance is 70% or more), external light will not enter the retroreflective optical element 2 and generate a ghost image that deteriorates the image quality of the image.

On the other hand, when the reflecting mirror 300 is removed, the plane image 3b of the real image is displayed in the direction perpendicular to the drawing (the direction of the plane of the transparent member 100). As a result, by sharing the same optical system, it is possible to realize a spatially floating image display device in which the position at which the spatially floating image is generated and the orientation with respect to the viewer are different depending on the presence or absence of the reflecting mirror.

Also, the configuration is such that the polarization separation member 101 can be rotated. By rotating the polarization separation member 101, the orientation and position of the spatially floating images 3 (3a and 3b) can be adjusted.

An absorptive polarizing plate 12 is provided on the external light entrance window of the transparent member 100 . The absorptive polarizing plate 12 absorbs the P-wave external light component and illumination light. When the image light is retroreflected by the retroreflective optical member 2, the polarization axes of part of the image light may become uneven. In that case, the image light passes through the polarization separation member 101 and returns to the display device 1 . This light is reflected again by the image display surface of the liquid crystal display panel 11 constituting the display device 1, generates a ghost image, and significantly degrades the image quality of the image floating in space. Therefore, in this embodiment, as shown in FIGS. 9A and 9B, the absorptive polarizing plate 12 is also provided on the image display surface of the display device 1 . By absorbing the image light that has returned to the display device 1 with the absorptive polarizing plate 12, deterioration of the image quality due to the ghost image of the image floating in space is prevented.

Furthermore, when external light is incident on the retroreflective optical member 2, a strong ghost image may be generated. Therefore, in this embodiment, the light blocking member 25 provided on the inner surface of the transparent member 100 at a portion other than the absorptive polarizing plate 12 of the external light entrance window prevents the external light from entering. The polarization separating member 101 is formed of a reflective polarizing plate, a transparent member formed of a metal multilayer film that reflects a specific polarized wave, or the like.

A light shielding member (not shown) for shielding oblique image light other than the regular image light forming the spatially floating image may be provided between the polarization separation member 101 and the liquid crystal display panel 11 . Also, between the retroreflective optical member 2 and the polarization separating member 101, a light shielding member (not shown) for shielding oblique image light other than normal image light may be provided. Furthermore, as described above, a light shielding member (not shown) is also provided so that external light does not directly enter the retroreflective optical member 2, and shields oblique light that causes a ghost image. The inventor confirmed through experiments that as a result, the occurrence of ghost images is suppressed.
<Reflective polarizing plate>

The reflective polarizing plate with the grid structure of this embodiment has deteriorated 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 (light source device 13) of this embodiment, which can emit image light emitted from the liquid crystal display panel 11 at a narrow angle, is an ideal light source. In addition, the characteristics in the horizontal direction are similarly degraded with respect to oblique light. Considering 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 at a narrower angle is used as the backlight of the liquid crystal display panel. This makes it possible to provide high-contrast spatial floating images.
<Display device>

Next, the display device 1 of this embodiment will be described with reference to the drawings. The display device 1 of the present embodiment includes an image display element (liquid crystal display panel) 11 and a light source device 13 constituting a light source thereof. is shown as an exploded perspective view.

This image display element (liquid crystal display panel) 11 has a narrow angle diffusion characteristic by light from a light source device 13, which is a backlight device, as indicated by arrows (outgoing light beams) 30 in FIG. It obtains an illumination light beam with characteristics similar to laser light whose polarization plane is aligned in one direction, and emits image light modulated according to the input image signal. . Then, the image light is reflected by the retroreflective optical member 2 and transmitted through the window glass to form a spatially floating image, which is a real image (see FIG. 1). 10, the display device 1 of this embodiment includes a liquid crystal display panel 11 that constitutes the display device 1, a light direction conversion panel 54 that controls the directivity of the light flux emitted from the light source device 13, and It is configured with a narrow angle diffuser (not shown) as required. That is, polarizing plates are provided on both sides of the liquid crystal display panel 11, and image light of a specific polarized wave is emitted after modulating the intensity of the light according to the image signal (see the arrow (outgoing light beam) 30 in FIG. 10). It has become. As a result, the display device 1 of the present embodiment projects a desired image as light of a specific polarized wave with high directivity (straightness) toward the retroreflective optical member 2 via the light direction conversion panel 54. , after being reflected by the retroreflective optical member 2, the light is transmitted toward the viewer's eyes inside/outside the vehicle (space) to form a spatially floating image. A protective cover may be provided on the surface of the light direction conversion panel 54 described above.

In this embodiment, in order to improve the utilization efficiency of the light flux 30 emitted from the light source device 13 and to significantly reduce the power consumption, the display device 1 including the light source device 13 and the liquid crystal display panel 11 has the following: can be configured. That is, the display device 1 projects light from the light source device 13 (see the arrow (emitted light flux) 30 in FIG. 10) toward the retroreflective optical member 2, reflects the light from the retroreflective optical member 2, and then projects it onto the window glass. A transparent sheet (not shown) provided on the surface of the projector can also control the directivity so as to form a spatially floating image at a desired position. Specifically, this transparent sheet controls the imaging position of the spatially floating image while imparting high directivity by an optical component such as a Fresnel lens or a linear Fresnel lens. According to this, the image light from the display device 1 efficiently reaches the observer outside the window glass (for example, sidewalk) with high directivity (straightness) like laser light. As a result, it is possible to display a high-definition spatial floating image with high resolution and significantly reduce the power consumption of the display device 1 including the LED (Light Emitting Diode) element 201 of the light source device 13 .
<Example 1 of display device>

An example of a specific configuration of the display device 1 is shown in FIG. 11, the liquid crystal display panel 11 and the light direction changing panel 54 are arranged on the light source device 13 of FIG. The light source device 13 is made of, for example, plastic, and includes an LED element 201 and a light guide 203 inside. As shown in FIG. 11 and the like, the end face of the light guide 203 is gradually cut off toward the light receiving part in order to convert the diverging light from each LED element 201 into a substantially parallel light flux. A lens shape is provided that has a shape that increases the area and that has the effect of gradually decreasing the divergence angle by performing total reflection multiple times while propagating inside. A liquid crystal display panel 11 constituting the display device 1 is attached to the upper surface of the light guide 203 . An LED element 201 as a semiconductor light source and an LED substrate 202 on which a control circuit for the LED element 201 is mounted are attached to one side surface (the left end surface in this example) of the case of the light source device 13 . In addition, a heat sink, which is a member for cooling the heat generated by the LED elements 201 and the control circuit, may be attached to the outer surface of the LED substrate 202 .

In addition, the frame (not shown) of the liquid crystal display panel 11 attached to the upper surface of the case of the light source device 13 is electrically connected to the liquid crystal display panel 11 attached to the frame and further to the liquid crystal display panel 11 . FPC (Flexible Printed Circuits: flexible printed circuit board) (not shown) and the like are attached. That is, the liquid crystal display panel 11, which is a liquid crystal display element, along with the LED element 201, which is a solid-state light source, modulates the intensity of transmitted light based on a control signal from a control circuit (not shown) that constitutes the electronic device. to generate the display image. At this time, the generated image light has a narrow diffusion angle and only a specific polarized wave component. Therefore, a new display device that has not existed in the past, which is similar to a surface emitting laser image source driven by a video signal, can be obtained. . At present, it is technically and safely impossible to obtain a laser beam having the same size as the image obtained by the display device 1 using a laser device. Therefore, in this embodiment, for example, light close to the above-described surface emitting laser image light is obtained from a luminous flux from a general light source provided with an LED element.

Next, the configuration of the optical system housed in the case of the light source device 13 will be described in detail with reference to FIG. 12 together with FIG. Since FIGS. 11 and 12 are sectional views, only one LED element 201 constituting the light source is shown. The light from the plurality of LED elements 201 is converted into substantially collimated light by the shape of the light receiving end face 203a of the light guide 203. As shown in FIG. For this reason, the light-receiving portion of the end surface of the light guide 203 and the LED element 201 are attached while maintaining a predetermined positional relationship. Each of the light guides 203 is made of translucent resin such as acryl. The LED light-receiving surface at the end of the light guide 203 has, for example, a conical convex outer peripheral surface obtained by rotating the parabolic cross section, and the top of the outer peripheral surface is convex to the central part of the top. (that is, a convex lens surface), and a convex lens surface projecting outward (or a concave lens surface recessed inward) may be provided at the center of the planar portion of the light receiving end surface 203a of the light guide 203. ) (not shown, similar to FIG. 13 and the like to be described later). The outer shape of the light receiving portion of the light guide body to which the LED element 201 is attached is a paraboloid that forms a conical outer peripheral surface. Further, the external shape of the light receiving portion of the light guide is set within a range in which the light emitted from the LED element 201 in the peripheral direction can be totally reflected inside the outer peripheral surface. Alternatively, a reflective surface is formed on the outer shape of the light receiving portion of the light guide.

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

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

As described above, the light source device 13 shown in FIG. 10 and the like is configured by attaching a light source unit in which a plurality of LED elements 201 as a light source are arranged on a light receiving end face 203a which is a light receiving portion provided on the end face of the light guide 203. ing. As a result, the divergent luminous flux from the LED element 201 is converted into substantially parallel light by the lens shape of the light receiving end face 203a of the end face of the light guide body 203, and the light is guided inside the light guide body 203 as indicated by the arrow (in the direction parallel to the drawing). Then, the light is emitted by the luminous flux direction converting means 204 toward the liquid crystal display panel 11 arranged substantially parallel to the light guide 203 (in the direction perpendicular to the front of the drawing). By optimizing the distribution (in other words, density) of the light beam direction changing means 204 according to the shape of the interior or surface of the light guide 203, the uniformity of the light beam incident on the liquid crystal display panel 11 can be controlled. The luminous flux direction changing means 204 described above converts the luminous flux propagating in the light guide 203 into a , toward the liquid crystal display panel 11 arranged substantially parallel to it (direction perpendicular to the front of the drawing). At this time, when the liquid crystal display panel 11 faces the center of the screen and the viewpoint is placed at the same position as the screen diagonal dimension, if the relative luminance ratio is 20% or more when comparing the luminance of the screen center and the screen peripheral part, There is no practical problem, and if it exceeds 30%, the characteristics will be even better.

12, similarly to FIG. 11, in the light source device 13 including the light guide 203 and the LED element 201 described above, the configuration and operation of the light source (light source device 13) of the present embodiment that converts the polarized light will be described. It is a cross-sectional layout diagram for. In FIG. 12, the light source device 13 includes, for example, a light guide 203 formed of plastic or the like and provided with a light beam direction changing means 204 on its surface or inside, an LED element 201 as a light source, a reflection sheet 205, a retardation plate 206, It is composed of a lenticular lens and the like. On the upper surface of the light source device 13, a liquid crystal display panel 11 is attached as an image display element, which has polarizing plates on the light source light entrance surface and the image light exit surface.

Also, the display device 1 may have the following configuration. In FIG. 11, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incidence surface (lower surface in the drawing) of the liquid crystal display panel 11 corresponding to the light source device 13 . The light source device 13 selectively reflects a polarized wave (for example, P wave) 212 on one side of the natural light flux 210 emitted from the LED element 201, and is provided on one side (lower side in the drawing) of the light guide 203. The light is reflected by the reflection sheet 205 and directed toward the liquid crystal display panel 11 again. Therefore, a λ/4 plate, which is a retardation plate, is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49 . With this configuration, the light is reflected by the reflection sheet 205 and passed through the λ/4 plate twice to convert the reflected light flux from P-polarized light to S-polarized light, thereby improving the utilization efficiency of the light source light as image light. The image light flux (arrow 213 in FIG. 11) whose light intensity is modulated by the image signal in the liquid crystal display panel 11 is incident on the retroreflective optical member 2100 as shown in FIG. And via the reflecting mirror 2120, a space floating image, which is a real image, is obtained in the space inside the vehicle, which is inside the windshield 6, or in the space outside the vehicle.

Also, the display device 1 may have the following configuration. In FIG. 12, a film or sheet-like reflective polarizing plate 49 is provided on the light source light incident surface (lower surface in the drawing) of the liquid crystal display panel 11 corresponding to the light source device 13 . The light source device 13 selectively reflects a polarized wave (for example, an S wave) 211 on one side of the natural light flux 210 emitted from the LED element 201, and is provided on one side (lower side in the drawing) of the light guide 203. The light is reflected by the reflection sheet 205 and directed toward the liquid crystal display panel 11 again. A λ/4 plate, which is a retardation plate, is provided between the reflection sheet 205 and the light guide 203 or between the light guide 203 and the reflective polarizing plate 49 . With this configuration, the light is reflected by the reflection sheet 205 and passed through the λ/4 plate twice to convert the reflected light flux from S-polarized light to P-polarized light, thereby improving the utilization efficiency of the light source light as image light. The image light flux (arrow 214 in FIG. 12) whose light intensity is modulated by the image signal on the liquid crystal display panel 11 is incident on the retroreflective optical member 2100 as shown in FIG. Via the reflecting mirror 2120, a space-floating image, which is a real image, is obtained in the space inside the vehicle, which is the inside of the windshield 6, or in the space outside the vehicle.

In the light source device 13 shown in FIGS. 11 and 12, 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 reflects the polarized component on one side. The obtained contrast ratio is obtained by multiplying the reciprocal of the cross transmittance of the reflective polarizing plate by the reciprocal of the cross transmittance obtained by the two polarizing plates attached to the liquid crystal display panel. This provides high contrast performance. In fact, the inventor confirmed through experiments that the contrast performance of the displayed image is improved by 10 times or more. As a result, a high-quality image comparable to that of a self-luminous organic EL was obtained.
<Example 2 of display device>

Next, another example of the specific configuration of the display device 1 will be described with reference to FIG. The light source device of the display device 1 converts a divergent luminous flux of natural light (P-polarized wave and S-polarized wave are mixed) from the LED 14 into a substantially parallel luminous flux (vertical direction in the drawing) by the LED collimator 18, and is a reflective type The light is reflected toward the liquid crystal display panel 11 (left and right directions in the drawing) by the light guide 304 . The light reflected by the reflective light guide 304 is incident on the wavelength plate 206 and the reflective polarizing plate 49 arranged between the liquid crystal display panel 11 and the reflective light guide 304 . A specific polarized wave (for example, S-polarized wave) is reflected by the reflective polarizing plate 49, converted in phase by the wave plate 206, returned to the reflecting surface of the reflective light guide 304, reflected, and passed through the wave plate 206 again. Then, the light is converted into polarized waves (for example, P-polarized waves) that pass through the reflective polarizing plate 49 .

As a result, the natural light from the LEDs 14 is aligned with a specific polarized wave (for example, P-polarized wave), enters the liquid crystal display panel 11, is luminance-modulated in accordance with the video signal, and displays an image on the panel surface. 13 shows a plurality of LEDs 14 constituting the light source (only one is shown in FIG. 13 because it is a vertical cross section), and these LEDs 14 are arranged with respect to the LED collimator 18. installed in position. Each of the LED collimators 18 is made of translucent resin such as acrylic or glass. As in the above example, the LED collimator 18 has a conical convex outer peripheral surface obtained by rotating the parabolic cross section, and at the top of the outer peripheral surface, a convex portion ( That is, it has a concave portion formed with a convex lens surface. In addition, the central portion of the planar portion of the LED collimator 18 has a convex lens surface projecting outward (or a concave lens surface recessed inward). In addition, the paraboloid that forms the conical outer peripheral surface of the LED collimator 18 is set within an angle range that allows the light emitted in the peripheral direction from the LED 14 to be totally reflected inside the outer peripheral surface, or , a reflective surface is formed.

The configuration described above is the same as that of the light source device of the display device 1 shown in FIG. Furthermore, the light converted into substantially parallel light by the LED collimator 18 shown in FIG. The reflected light of the other polarized wave passes through the reflective light guide 304 again and is reflected by the reflector 271 provided on the other surface of the reflective light guide 304 that is not in contact with the liquid crystal display panel 11 . At this time, the light passes twice through the λ/4 plate 270, which is a retardation plate placed between the reflector 271 and the liquid crystal display panel 11, and undergoes polarization conversion. Then, the light is transmitted through the reflective polarizing plate 49 provided on the opposite surface, and enters the liquid crystal display panel 11 with the polarization direction aligned. As a result, in this configuration, all the light from the light source can be used, and the light utilization efficiency is doubled.

Light emitted from the liquid crystal display panel, as shown in FIGS. 17A and 17B, is emitted from the liquid crystal display panel in the horizontal direction of the screen (represented by the X-axis in FIG. 17A) and the vertical direction of the screen (represented by the Y-axis in FIG. 17A). Both have similar diffusion properties. On the other hand, the diffusion characteristic of the emitted light flux from the liquid crystal display panel of this embodiment is, for example, as shown in Example 1 of FIGS. 18A and 18B. By setting the angle to 13 degrees, it becomes 1/5 of the conventional angle of 62 degrees. Similarly, the viewing angle in the vertical direction is not uniform in the vertical direction, and the angle of reflection of the reflective light guide 304, the area of the reflecting surface, etc. are adjusted so that the viewing angle of the upper side is suppressed to about 1/3 of the viewing angle of the lower side. to optimize. As a result, in this embodiment, compared with the conventional liquid crystal TV, the amount of image light directed toward the viewing direction is greatly improved, and the luminance is 50 times or more. Note that the X and Y directions in FIGS. 18A and 18B are the same as in FIG. 17A.

Furthermore, if the viewing angle characteristics shown in Example 2 of FIGS. 18A and 18B are used, the viewing angle at which the brightness is 50% of the front view (angle of 0 degrees) is 5 degrees. 1/12. Similarly, the angle of view in the vertical direction is uniform in the vertical direction, and the angle of reflection and the area of the reflective surface of the reflective light guide 304 are optimized so that the angle of view is suppressed to about 1/12 of the conventional angle. As a result, in this embodiment, compared with the conventional liquid crystal TV, the amount of image light directed toward the viewing direction is greatly improved, and the luminance is 100 times or more.

As described above, by narrowing the viewing angle, the amount of luminous flux in the viewing direction can be concentrated, which greatly improves the efficiency of light utilization. As a result, according to the embodiment, even if a conventional liquid crystal display panel for TV is used, by controlling the light diffusion characteristics of the light source device, it is possible to achieve a significant improvement in luminance with the same power consumption. The display device can be directed to the outdoors.

As shown in FIGS. 3 and 4, the basic configuration of the embodiment is that a light beam having a narrow-angle directional characteristic is made incident on the liquid crystal display panel 4 by a light source device 10, and luminance is modulated in accordance with a video signal. A spatially floating image 220 obtained by reflecting the image information displayed on the screen of the display panel 4 by the retroreflective optical member 2100 is displayed indoors or outdoors.
<Example 1 of light source device>

Next, a configuration example of the optical system such as the light source device housed in the case will be described in detail with reference to FIG. 14 as well as FIGS. 15A and 15B.

14, 15A, and 5B show the LEDs 14 (14a, 14b) that constitute the light source, and these LEDs 14 are attached to the LED collimator 15 at predetermined positions. Each of the LED collimators 15 is made of translucent resin such as acrylic. 15B, the LED collimator 15 has a conical outer peripheral surface 156 obtained by rotating the parabolic cross section, and at the top of the outer peripheral surface 156, at the center of the top. It has a concave portion 153 in which a convex portion (that is, convex lens surface) 157 is formed. In addition, in the central portion of the planar portion of the LED collimator 15, there is provided a convex lens surface (or a concave lens surface recessed inward) 154 projecting outward. The paraboloid 156 forming the conical outer peripheral surface of the LED collimator 15 can totally reflect the light emitted from the LEDs 14 (14a, 14b) in the peripheral direction inside the paraboloid 156 on the outer peripheral surface. It is set within the range of possible angles, or a reflective surface is formed.

Also, the LEDs 14 (14a, 14b) are arranged at predetermined positions on the surface of the LED board 102, which is the circuit board. The LED board 102 is arranged and fixed to the LED collimator 15 so that the LEDs 14 on its surface are positioned in the center of the concave portions 153 of the LED collimator 15 .

According to such a configuration, the above-described LED collimator 15 reduces the light emitted from the LED 14 (14a or 14b), particularly the light emitted upward (to the right in the drawing) from the central portion of the LED 14. are condensed by two convex lens surfaces 157 and 154 that form the outer shape of the LED collimator 15 and become parallel light. Also, the light emitted in the peripheral direction from other portions is reflected by the parabolic surface 156 that forms the conical outer peripheral surface of the LED collimator 15, and is similarly condensed into parallel light. In other words, according to the LED collimator 15 having a convex lens in its central part and a parabolic surface in its peripheral part, almost all of the light generated by the LED 14 (14a or 14b) is taken out 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 exit side of the LED collimator 15 in FIG. As is clear from FIG. 15A, the polarization conversion element 21 includes a columnar translucent member having a parallelogram cross section (hereinafter referred to as a parallelogram prism) and a columnar light transmitting member having a triangular cross section (hereinafter referred to as a triangular prism). ), and arranged in an array parallel to a plane perpendicular to the optical axis of the parallel light from the LED collimator 15 . Further, a polarizing beam splitter (referred to as a PBS film) 2111 and a reflective film 2121 are alternately provided at the interface between the adjacent translucent members arranged in an array. A λ/2 phase plate 213 is provided on the exit surface from which the light that has entered the polarization conversion element 21 and passed through the PBS film 2111 is emitted.

A rectangular synthetic diffusion block 16 also shown in FIG. 15A is further provided on the output surface of this polarization conversion element 21 . That is, the light emitted from the LED 14 (14a or 14b) becomes parallel light by the function of the LED collimator 15 and enters the composite diffusion block 16. After being diffused by the texture 161 on the output side of the composite diffusion block 16, It reaches the light guide 17 .

The light guide 17 is a rod-shaped member with a substantially triangular cross section (see FIG. 15B) made of translucent resin such as acrylic. As is clear from FIG. 14, the light guide 17 has a light guide light entrance portion (a light guide light entrance surface) facing the output surface of the combined diffusion block 16 via the first diffuser plate 18a. ) 171, a light guide light reflecting portion (including a light guide light reflecting surface) 172 forming an inclined surface, and a second diffusion plate 18b, facing the liquid crystal display panel 11, which is a liquid crystal display element. and a light guide light emitting portion (including a light guide light emitting surface) 173 .

As shown in FIG. 14, which is a partially enlarged view, the light guide body light reflecting portion (surface) 172 of the light guide body 17 has a large number of reflecting surfaces 172a and connecting surfaces 172b alternately arranged in a sawtooth shape. formed. Reflecting surface 172a (a line segment rising to the right in the drawing) forms an angle αn (n: a natural number) with respect to a horizontal plane (horizontal direction in the drawing) indicated by a dashed line in the drawing. ~130). As an example, here, the angle αn is set to 43 degrees or less (0 degrees or more).

The light guide entrance portion (surface) 171 is formed in a curved convex shape that is inclined toward the light source. According to this, the parallel light from the output surface of the synthetic diffusion block 16 is diffused via the first diffusion plate 18a and enters the light guide entrance portion (surface) 171, as is clear from the drawing. , reaches a light guide light reflection portion (surface) 172 while being slightly bent (in other words, deflected) upward by a light guide entrance portion (surface) 171 . The light is reflected by the light guide light reflecting portion (surface) 172 and reaches the liquid crystal display panel 11 provided above the upper light guide light emitting portion 173 in the drawing.

According to the display device 1 described in detail above, it is possible to further improve the light utilization efficiency and its uniform illumination characteristics, and at the same time, to manufacture it in a small size and at a low cost, including a modularized light source device for S-polarized waves. becomes. In the above description, the polarization conversion element 21 is attached after the LED collimator 15, but the present invention is not limited to this. Similar actions and effects can also be obtained.

The light guide body light reflecting portion (surface) 172 has a large number of reflecting surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth shape. upwards. Furthermore, a narrow-angle diffusion plate is provided on the light guide light emitting portion (surface) 173, and the illumination light beam is incident on the light direction conversion panel 54 for controlling the directivity characteristics as a substantially parallel diffused light beam, thereby controlling the directivity characteristics. 14, and enters the liquid crystal display panel 11 from an oblique direction as shown in FIG. In this embodiment, the light direction conversion panel 54 is provided between the light guide exit surface 173 and the liquid crystal display panel 11 , but the present invention is not limited to this, and the light direction conversion panel 54 is provided on the exit surface of the liquid crystal display panel 11 . A similar effect can be obtained.
<Example 2 of light source device>

Another example of the configuration of the optical system such as the light source device 13 is shown in FIGS. 16A and 16B. Similar to the example shown in FIG. 14, FIGS. 16A and 16B show a plurality of (two in this example) LEDs 14 (14a, 14b) forming a light source. These LEDs 14 are mounted at predetermined positions with respect to the LED collimator 15 . Each of the LED collimators 15 is made of translucent resin such as acrylic. 14, this LED collimator 15 has a conical convex outer peripheral surface 156 obtained by rotating the parabolic cross section, and the top of the outer peripheral surface 156 has a center of the top. It has a concave portion 153 in which a convex portion (that is, a convex lens surface) 157 is formed. In addition, the LED collimator 15 has a convex lens surface (or an inward concave lens surface) 154 projecting outward at the central portion of the planar portion. In addition, the paraboloid 156 forming the conical outer peripheral surface of the LED collimator 15 is set within an angle range in which the light emitted from the LED 14 in the peripheral direction can be totally reflected inside the paraboloid 156. Alternatively, a reflective surface is formed.

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

According to such a configuration, among the light emitted from the LED 14 (14a or 14b) by the above-described LED collimator 15, the light emitted from the central portion of the LED upward (to the right in the drawing) is , are condensed by two convex lens surfaces 157 and 154 that form the outer shape of the LED collimator 15 and become parallel light. Also, the light emitted in the peripheral direction from other portions is reflected by the parabolic surface 156 that forms the conical outer peripheral surface of the LED collimator 15, and is similarly condensed into parallel light. In other words, according to the LED collimator 15 having a convex lens in its central part and a parabolic surface in its peripheral part, almost all of the light generated by the LED 14 (14a or 14b) is taken out as parallel light. It becomes possible to improve the utilization efficiency of the generated light.

In FIG. 16A, a light guide 170 is provided on the light emitting side of the LED collimator 15 via the first diffusion plate 18a. The light guide 170 is a rod-shaped member with a substantially triangular cross section made of translucent resin such as acryl. As is clear from FIG. 16A, the light guide 170 has a light guide entrance portion (surface) 171 of the light guide 170 that faces the exit surface of the diffusion block 16 via the first diffuser plate 18a. , a light guide light reflecting portion (surface) 172 forming an inclined surface, and a light guide light emitting portion (surface) 173 facing the liquid crystal display panel 11, which is a liquid crystal display element, with the reflective polarizing plate 200 interposed therebetween. ing.

For this reflective polarizing plate 200, for example, a material having characteristics of reflecting P-polarized light and transmitting S-polarized light is selected. Then, this reflective polarizing plate 200 reflects the P-polarized light out of the natural light emitted from the LED, which is the light source, and the λ/4 plate 5002 provided in the light guide light reflecting section 172 shown in FIG. After passing through the reflecting surface 5001, the light is reflected by the λ/4 plate 5002 and converted into S-polarized light. As a result, all the light beams incident on the liquid crystal display panel 11 are unified into S-polarized light.

Similarly, as the reflective polarizing plate 200, a plate having characteristics of reflecting S-polarized light and transmitting P-polarized light may be selected. By doing so, this reflective polarizing plate 200 reflects the S-polarized light out of the natural light emitted from the LED, which is the light source, and the λ/4 plate 5002 provided in the light guide light reflecting section 172 shown in FIG. After passing through the reflection surface 5001, the light is reflected by the λ/4 plate 5002 and converted into P-polarized light. As a result, all the light beams incident on the liquid crystal display panel 52 are unified into P-polarized light. Polarization conversion can also be achieved with the configuration described above.
<Example 3 of light source device>

Another example of the configuration of the optical system such as the light source device will be described with reference to FIG. In this example, as shown in FIG. 13, a diverging luminous flux of natural light (P-polarized and S-polarized mixed) from the LED 14 is converted into a substantially parallel luminous flux by the collimator lens 18, and the reflective light guide 304 is used to convert the divergent luminous flux to the liquid crystal display panel 11. reflect towards. The reflected light enters the reflective polarizing plate 206 arranged between the liquid crystal display panel 11 and the reflective light guide 304 . A specific polarized wave (for example, S-polarized wave) is reflected by the reflective polarizing plate 206 , and the reflected light is transmitted through the surface connecting the reflecting surfaces of the reflective light guide 304 to the opposite surface of the reflective light guide 304 . The light is reflected by the reflecting plate 271 arranged as a light beam, and is polarized by being transmitted through the λ/4 wavelength plate 270, which is a phase plate, twice. The polarization-converted light (for example, P-polarized light) passes through the reflective light guide 304 and the reflective polarizing plate 206, enters the liquid crystal display panel 11, and is modulated into image light. At this time, by combining the specific polarized wave and the polarized plane after polarization conversion, the light utilization efficiency is doubled, and the degree of polarization (in other words, extinction ratio) of the reflective polarizer 206 is also equal to the extinction ratio of the entire system. can ride Therefore, by using the light source device of this embodiment, the contrast ratio of the spatially floating image display device is greatly improved.

As a result, in this embodiment, the natural light from the LED 14 is aligned with a specific polarized wave (for example, P polarized wave). As in the previous example, in this embodiment, a plurality of LEDs 14 constituting the light source are provided (only one is shown in FIG. mounted in place. Each of the LED collimators 18 is made of translucent resin such as acrylic or glass. And this LED collimator 18 has an outer peripheral surface of conical convex shape obtained by rotating the parabolic cross section in the same manner as described above. It has a recess that forms a In addition, the central portion of the planar portion of the LED collimator 18 has a convex lens surface projecting outward (or a concave lens surface recessed inward). In addition, the paraboloid that forms the conical outer peripheral surface of the LED collimator 18 is set within an angle range that allows the light emitted in the peripheral direction from the LED 14 to be totally reflected inside the paraboloid, Alternatively, a reflective surface is formed.

Also, the LEDs 14 are arranged at predetermined positions on the surface of the LED board 102, which is the circuit board. The LED substrate 102 is arranged and fixed to the LED collimator 18 so that the LEDs 14 on its surface are positioned in the central portion of the concave portion of the LED collimator 18 .

According to such a configuration, the light emitted from the LED 14 by the LED collimator 18, particularly the light emitted from the central portion thereof, is condensed by the two convex lens surfaces forming the outer shape of the LED collimator 18 and collimated. become light. Also, the light emitted in the peripheral direction from other portions is reflected by the parabolic surface that forms the conical outer peripheral surface of the LED collimator 18, and is similarly condensed into parallel light. In other words, according to the LED collimator 18 having a convex lens in the center and a paraboloid in the periphery, almost all of the light generated by the LED 14 can be extracted as parallel light. It is possible to improve the utilization efficiency of the generated light.
<Example 4 of light source device>

Furthermore, another example of the configuration of the optical system such as the light source device will be described with reference to FIG. In FIG. 19, two optical sheets (in other words, a diffusion sheet, a diffusion film) 207 for converting the diffusion characteristics are used on the light exit side of the LED collimator 18, and the light from the LED collimator 18 is distributed between these two sheets. The light is made incident between the optical sheets 207 . The optical sheet 207 converts diffusion characteristics in the vertical direction (vertical direction, vertical direction within the screen) and horizontal direction (front-rear direction, horizontal direction within the screen) in the drawing constituting the surface. When the optical sheet 207 is composed of one sheet, the diffusion characteristics in the vertical and horizontal directions are controlled by the fine shapes of the front and back surfaces of the sheet. Also, a plurality of optical sheets (diffusion sheets) may be used to share the action. Due to the surface shape and the back surface shape of the optical sheet 207, the diffusion angle of the light from the LED collimator 18 in the vertical direction of the screen is matched to the width of the vertical surface of the reflection surface of the optical sheet (diffusion sheet) 207, and the horizontal direction is the same as that of the liquid crystal display panel. The number of LEDs 14 and the angle of divergence from the optical element (optical sheet 207) should be optimally designed as design parameters so that the surface density of the luminous flux emitted from 11 is uniform. That is, in this embodiment, the diffusion characteristics are controlled by the surface shape of one or more optical sheets (diffusion sheets) 207 instead of the light guide 304 described above. In this embodiment, the polarization conversion is performed in the same manner as in Example 3 of the light source device described above. On the other hand, the polarization conversion element 21 may be provided between the LED collimator 18 and the optical sheet 207 so that the light from the light source is incident on the optical sheet 207 after the polarization conversion.

For the reflective polarizing plate 206 described above, for example, one having characteristics of reflecting S-polarized light and transmitting P-polarized light is selected. Then, of the natural light emitted from the LED 14, which is the light source, S-polarized light is reflected by the reflective polarizing plate 206, passes through the retardation plate 270, is reflected by the reflecting surface 271, and passes through the retardation plate 270 again. As a result, the light is converted into P-polarized light and enters the liquid crystal display panel 11 . The thickness of the retardation plate 270 must be optimized depending on the angle of incidence of light rays on the retardation plate 270, and the optimum value exists in the range from λ/16 to λ/4.
<Example 5 of light source device>

Another example of the configuration of the optical system of the light source device will be explained using FIGS. 20A to 20C. In this embodiment, as shown in FIG. 20C, the light source device 13 includes a polarization conversion element 501 on the light exit side of the LED collimator 18. The polarization conversion element 501 identifies the natural light from the LED element (LED 14). , and enters the optical element 81 that controls the diffusion characteristics. The optical element 81 controls the diffusion characteristics of the incident light in the vertical direction (vertical direction) and horizontal direction (front-rear direction) in FIG. To optimize light distribution characteristics. On the surface of the reflective light guide 200, as shown in FIG. (not shown) to obtain the desired diffusion properties. The placement accuracy of the LED element (LED 14) of the light source and the LED collimator 18 greatly affects the efficiency of the light source. Therefore, an optical axis accuracy of about 50 μm is normally required. Therefore, the inventor has made the following configuration as a countermeasure against the problem that the mounting accuracy is lowered due to the expansion of the LED collimator 18 due to the heat generated by the LED 14 . That is, in this embodiment, as shown in FIGS. 20A and 20B, the structure of a light source unit 503 integrating several LED elements (LEDs 14) and an LED collimator 18 includes a single or multiple (three in this example) By using the light source unit 503 in the light source device, the decrease in mounting accuracy is reduced.

In the embodiment shown in FIGS. 20A to 20C, light source units integrating light LED elements and LED collimators 18 are provided at both ends of the reflective light guide 200 in the long side direction (horizontal direction in the drawing). 503 are incorporated (six in total). In this embodiment, three light source units 503 are incorporated in each of the left and right sides of the reflective light guide 200 in the vertical direction within the screen (vertical direction in FIG. 20B). As a result, uniform luminance of the light source device 13 is achieved. A plurality of concavo-convex patterns 502 substantially parallel to the light source unit 503 are formed on the reflecting surface of the reflective light guide 200 (the surface on which the concavo-convex pattern 502 is formed in FIG. 20B). The cross section on which the unevenness of the uneven pattern 502 is formed is the plane in FIG. 20C, the direction of repeating the unevenness of the uneven pattern 502 is the horizontal direction in FIG. is the vertical direction of Even in one uneven pattern 502, a polyhedron is formed on its surface. As a result, the amount of light incident on the image display device can be controlled with high precision. In this embodiment, the shape of the reflective surface of the reflective light guide 200 is described as the uneven pattern 502. However, the present invention is not limited to this, and a pattern in which shapes such as triangular surfaces and corrugated surfaces are regularly or irregularly arranged. As a result, the light distribution pattern directed from the reflective light guide 200 to the image display device may be controlled by the shape of the pattern surface. Moreover, as shown in FIG. 20A , a side surface of the reflective light guide 200 (the side surface on which the light source unit 503 is not provided) is provided with a light source to prevent the light controlled by the LED collimator 18 from leaking from the light source device 13 to the outside. A light shielding wall 504 is provided on the outside, and a metallic substrate 505 provided on the outside of the LED element (LED 14) is designed to enhance heat dissipation.
<Lenticular lens>

The action of the lenticular lens that controls the diffusion characteristics of the light emitted from the display device 1 will be described below. By optimizing the lens shape of the lenticular lens, the light emitted from the display device 1 described above can be transmitted through or reflected by the window glass (FIG. 1) to efficiently obtain a spatially floating image. That is, in the present embodiment, for image light from the display device 1, a sheet for controlling diffusion characteristics is provided by combining two lenticular lenses or arranging microlens arrays in a matrix. Then, in the X-axis and Y-axis directions (FIGS. 18A and 18B) in the screen, the luminance (in other words, relative luminance) of the image light can be controlled according to the angle of reflection (0 degrees in the vertical direction). can. In this embodiment, compared with the conventional lenticular lens, as shown in FIG. By changing the balance of characteristics, the luminance (relative luminance) of light due to reflection and diffusion is increased. As a result, in this embodiment, like the image light from the surface emitting laser image source, the diffusion angle is narrow (in other words, the straightness is high), and the image light has only a specific polarized wave component, and the conventional technology is used. It is possible to suppress the ghost image generated by the retroreflective optical member in the case of the retroreflective optical member, and to efficiently control the space floating image to reach the eye of the viewer due to the retroreflection.

In addition, with the light source device described above, the diffusion characteristics of emitted light from the general liquid crystal display panel shown in FIGS. By adopting a directivity characteristic with a narrow angle, it is possible to realize a display device that emits light of a specific polarized wave that emits an image light beam that is nearly parallel to a specific direction.

17A and 17B show an example of the characteristics of the lenticular lens employed in this embodiment. This example particularly shows the characteristics in the X direction (vertical direction) in FIG. 17A. In FIG. 17B, the characteristic O has a peak in the light emission direction at an angle of about 30 degrees upward from the vertical direction (0 degrees), and shows vertically symmetric luminance characteristics. Further, characteristic A and characteristic B show examples of characteristics in which the luminance (relative luminance) is increased by condensing the image light above the peak luminance near 30 degrees. Therefore, in these characteristics A and B, the luminance (relative luminance) of the light sharply decreases compared to the characteristic O at angles exceeding 30 degrees.

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

According to this embodiment, in place of the conventional HUD device, necessary images are displayed as spatially floating images in the interior of the vehicle, particularly in the space sandwiched between the windshield and the driver, without reflecting the images on the windshield. It is possible to provide a spatially floating image display device capable of As a result, it is possible to provide a space-floating image display device that can be deployed between vehicle models having different body designs.

In addition, according to the present embodiment, it is possible to deploy between vehicle models with different windshield shapes and inclinations, which has been an obstacle to installation compared to the HUD of the prior art. can be realized.

Further, according to the present embodiment, the imaging point of the retroreflected image is shifted in the depth direction with respect to the display plane by the surface shape of the reflecting mirror that constitutes the spatially floating image display device, thereby creating a pseudo-stereoscopic image. Furthermore, the effect of stereoscopic display is emphasized by forming shadows and signal components corresponding to the shadows in the display image and superimposing them on the original signal. Thereby, a suitable spatial floating image display device can be realized.

Although various embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiment describes the entire apparatus in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

With the technology according to this embodiment, by displaying high-resolution and high-brightness video information in a floating state, for example, users can operate without feeling uneasy about contact infection of infectious diseases. If the technology according to this embodiment is applied to a system used by an unspecified number of users, it will be possible to reduce the risk of contact infection of infectious diseases and provide a non-contact user interface that can be used without anxiety. . In this way, we will contribute to "3 good health and well-being for all" in the Sustainable Development Goals (SDGs) advocated by the United Nations.

In addition, in the technology according to the present embodiment, by making the angle of divergence of emitted image light small and aligning it to a specific polarized wave, only normal reflected light can be efficiently reflected by the retroreflective member. To obtain a bright and clear spatial floating image with high utilization efficiency. According to the technology according to the present embodiment, it is possible to provide a highly usable non-contact user interface capable of significantly reducing power consumption. In this way, we will contribute to the Sustainable Development Goals (SDGs) advocated by the United Nations, namely, "9: Build a foundation for industry and technological innovation" and "11: Sustainable urban development."

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

DESCRIPTION OF SYMBOLS 1... Display apparatus 2... Retroreflection optical member 3... Spatial floating image 4... Image display apparatus 10... Light source device 11... Liquid crystal display panel 21... Polarization conversion element 6... Windshield 8... Eye point 100 Transmissive plate 1000 Spatial floating image display device 101 Polarization separation member 12 Absorptive polarizing plate 13 Light source device 41 Opening 110 Housing 203 Light guide 2140 Reflective

polarizing plate

205, 271

Reflective sheet

206, 270 Retardation plate 301 Ghost image of floating image 2100 Retroreflective

optical member

300, 2110 Reflective mirror 2120 Reflective

optical element

60, 220... Spatial floating image (space floating image), G1, G2, G3, G4, G6... Spatial floating image ghost image, R1... Spatial floating image, 401... Concave mirror, 403... Optical element, 404... Image display Equipment (liquid crystal display panel).

Claims

A spatially floating image display device for forming a spatially floating image,
a display panel for displaying images;
a light source device that supplies light to the display panel;
a retroreflection plate that reflects image light from the display panel and displays a space floating image, which is a real image, in the air by the reflected light;
and a reflecting mirror that reflects light that has passed through the retroreflector,
The reflecting mirror has a convex or concave shape, and displays a spatially floating image with a curved image plane corresponding to the shape of the reflecting mirror.
Spatial floating image display device.
In the spatial floating image display device according to claim 1,
The light forming the spatially floating image travels obliquely upward from the reflecting mirror toward the spatially floating image.
Spatial floating image display device.
In the spatial floating image display device according to claim 1,
The spatially floating image is displayed in a state including an image representing a shadow.
Spatial floating image display device.
A spatially floating image display device for forming a spatially floating image,
an opening through which image light of a specific polarized wave that forms the spatially floating image passes;
a transparent member arranged in the opening and through which the image light passes;
a light source device having narrow-angle diffusion characteristics;
a video source that emits a specific polarized light;
a retroreflective optical member having a retardation plate on a retroreflective surface;
one or more reflective mirrors;
a polarization separating member provided in a space connecting the image source and the retroreflective optical member;
with
image light of a specific polarized wave from the image source is once transmitted through the polarization separation member;
one polarized wave of the image light is converted into the other polarized wave by polarization-converting the image light transmitted through the polarization separation member by the retroreflective optical member;
the image light after the polarization conversion is reflected by the polarization separation member, and the image light flux forming the spatially floating image is reflected by the plurality of reflecting mirrors and directed toward a viewer;
By substantially matching the shape of at least one of the reflecting mirrors and the imaging point of the retroreflected image from the retroreflective optical member in the depth direction, the left-right direction, the up-down direction, or a combination of these directions from the viewing side. It is possible to simulate stereoscopic display,
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
The shape of at least one of the reflecting mirrors and the imaging point of the retroreflected image from the retroreflective optical member are substantially aligned in the depth direction, the left-right direction, the up-down direction, or a combination thereof from the viewing side, and By superimposing video information in the depth direction on the video signal, the spatially floating video is displayed in a pseudo-stereoscopic manner.
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
At least one reflective mirror is provided as the reflective mirror in an optical path connecting the spatially floating image and the polarization separation member;
rotating the at least one reflective mirror within the optical path to change the position at which the spatial floating image is formed;
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
At least one reflective mirror is provided as the reflective mirror in an optical path connecting the spatially floating image and the polarization separation member;
Among the at least one reflecting mirror, the reflecting mirror arranged closest to the floating image is formed of a metal multilayer film that reflects a specific polarized wave of the image light and transmits the other polarized wave.
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
The polarization separation member is formed of a reflective polarizing plate or a metal multilayer film that reflects a specific polarized wave,
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
Having an absorptive polarizing plate on at least one surface of the transparent member,
Spatial floating image display device.
In the spatial floating image display device according to claim 4,
The transparent member is formed of a transparent material in a portion through which the image light passes, and is formed of a light shielding member in a portion through which the image light does not pass.
Spatial floating image display device.
A spatially floating image display device for forming a spatially floating image,
an opening through which image light of a specific polarized wave that forms the spatially floating image passes;
a transparent member arranged in the opening and through which the image light passes;
a light source device having narrow-angle diffusion characteristics;
a video source that emits a specific polarized light;
a retroreflective optical member having a retardation plate on a retroreflective surface;
one or more reflective mirrors;
a polarization separating member provided in a space connecting the image source and the retroreflective optical member;
with
image light of a specific polarized wave from the image source is once transmitted through the polarization separation member;
one polarized wave of the image light is converted into the other polarized wave by polarization-converting the image light transmitted through the polarization separation member by the retroreflective optical member;
reflecting the image light after the polarization conversion by the polarization separation member to form a spatially floating image by the plurality of reflecting mirrors;
With respect to the optical axis connecting the center of the final reflection mirror and the center of the retroreflection optical element so that the external light does not return to the retroreflection optical element due to the reflection of the final reflection mirror that returns the image light beam and is directed to the viewer. wherein the final reflection mirror is tilted at
Spatial floating image display device.
In the spatial floating image display device according to claim 11,
The final reflecting mirror is provided with a reflecting film having a reflectance of 85% or more for a specific polarized wave and a reflectance of 20% or less for the other polarized wave.
Spatial floating image display device.
In the spatial floating image display device according to claim 11,
Having an antireflection film on the image display surface of the liquid crystal display panel,
Having an absorptive polarizing plate provided on the liquid crystal display panel,
Absorbing the reflected light by the absorptive polarizing plate;
Spatial floating image display device.
A spatially floating image display device for forming a spatially floating image,
an opening through which image light of a specific polarized wave that forms the spatially floating image passes;
a transparent member arranged in the opening and through which the image light passes;
a light source device having narrow-angle diffusion characteristics;
a video source that emits a specific polarized light;
a retroreflective optical member having a retardation plate on a retroreflective surface;
one or more reflective mirrors;
a polarization separating member provided in a space connecting the image source and the retroreflective optical member;
with
image light of a specific polarized wave from the image source is once transmitted through the polarization separation member;
one polarized wave of the image light is converted into the other polarized wave by polarization-converting the image light transmitted through the polarization separation member by the retroreflective optical member;
the converted image light is reflected by the polarization splitting member, and the image light flux forming a spatially floating image is reflected by the plurality of reflecting mirrors and directed toward a viewer;
image light of a specific polarized wave from the image source is once transmitted through the polarization separating member toward the retroreflective optical member;
one polarized wave is converted into the other polarized wave by polarization-converting the image light transmitted through the polarization separation member by the retroreflective optical member;
reflecting the image light after the polarization conversion toward the opening by the polarization separation member;
displaying the space floating image, which is a real image, outside the transparent member in the opening based on the image light reflected by the polarization separation member;
The retroreflective member is arranged at an angle with respect to the image source, is arranged at a position away from the opening through which retroreflected image light from the retroreflective member passes, and is configured to block the incidence of external light. ,
changing the position at which the spatial floating image is formed by a structure that changes the distance from the image source to the retroreflective optical member;
Spatial floating image display device.
In the spatial floating image display device according to claim 14,
The image source is arranged at a position away from the opening through which the retroreflected image light passes and at a position where the image light emitted from the image source cannot be visually recognized from the opening.
Spatial floating image display device.
In the spatial floating image display device according to claim 14,
image light forming the spatially floating image emitted from the opening is reflected by one of the reflecting mirrors,
The angle of the one reflective mirror is set at a desired angle with respect to the plane of the aperture to change the position and angle of the spatially floating image.
Spatial floating image display device.
In the spatial floating image display device according to claim 14,
image light emitted from the opening and forming the spatially floating image is reflected by one of the reflecting mirrors,
The one reflecting mirror has a characteristic of high reflectance of a specific polarized wave,
Spatial floating image display device.
In the spatial floating image display device according to any one of claims 1 to 17,
The image displayed on the liquid crystal display panel is an image that corrects image distortion generated in the optical system that forms the spatially floating image.
Spatial floating image display device.
A spatially floating image display device for forming a spatially floating image,
an opening through which image light of a specific polarized wave that forms the spatially floating image passes;
a transparent member arranged in the opening and through which the image light passes;
a light source device having narrow-angle diffusion characteristics;
a video source that emits a specific polarized light;
a retroreflective optical member having a retardation plate on a retroreflective surface;
a reflective mirror;
a polarization separating member provided in a space connecting the image source and the retroreflective optical member;
with
image light of a specific polarized wave from the image source is once transmitted through the polarization separation member;
one polarized wave of the image light is converted into the other polarized wave by polarization-converting the image light transmitted through the polarization separation member by the retroreflective optical member;
The image light after the polarization conversion is reflected by the polarization separation member, and the image light flux forming the spatially floating image is reflected by the reflection mirror and directed to a viewer,
reflecting the image light after the conversion by the reflecting mirror again;
reflecting the image light reflected again by the reflecting mirror toward the opening;
displaying the space floating image, which is a real image, outside the transparent member of the opening;
changing the position at which the spatial floating image is formed by a structure that changes the distance from the image source to the retroreflective optical member;
The surface roughness of the reflective surface of the retroreflective optical member is set so that the ratio of the blur amount of the spatial floating image and the pixel size of the image source is 40% or less,
The light source device includes a point-like or planar light source, optical means for reducing the angle of divergence of light from the light source, polarization conversion means for aligning the light from the light source into polarized light in a specific direction, and the image source. a light guide having a propagating reflective surface,
adjusting the image light by the shape and surface roughness of the reflecting surface provided on the light source device;
An image light flux having a narrow divergence angle from the image source is reflected by the retroreflective optical member to form the spatially floating image in the air.
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
The surface roughness of the reflective surface of the retroreflective optical member is set to be 160 nm or less,
The light source device includes a point-like or planar light source, optical means for reducing the angle of divergence of light from the light source, polarization conversion means for aligning the light from the light source into polarized light in a specific direction, and the image source. a light guide having a propagating reflective surface,
The light guide is arranged to face the image source, and is provided with a reflecting surface inside or on the surface for reflecting the light from the light source device toward the image source. propagating light,
The image source modulates the light intensity according to the image signal,
An image light flux having a narrow divergence angle from the image source is reflected by the retroreflective member to form the spatially floating image in the air.
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
The light source device adjusts part or all of the divergence angle of the luminous flux according to the shape and surface roughness of the reflecting surface of the light source device so that the light divergence angle of the liquid crystal display panel is within ±30 degrees. ,
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
The light source device adjusts part or all of the divergence angle of the luminous flux according to the shape and surface roughness of the reflecting surface of the light source device so that the light divergence angle of the liquid crystal display panel is within ±15 degrees. ,
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
In the light source device, part or all of the divergence angle of the luminous flux is adjusted to the shape and surface of the reflecting surface of the light source device so that the divergence angle of light rays of the liquid crystal display panel differs between the horizontal divergence angle and the vertical divergence angle. Adjust according to roughness,
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
The light source device has a contrast performance obtained by multiplying the contrast obtained by the characteristics of the polarizing plates provided on the light incident surface and the light emitting surface of the image source by the reciprocal of the polarization conversion efficiency of the polarization conversion means.
Spatial floating image display device.
In the spatial floating image display device according to claim 19,
a reflective polarizing plate;
and the retardation plate provided on the image light incident surface of the retroreflective optical member,
The reflective polarizing plate is arranged so that image light from the image source is once reflected by the reflective polarizing plate and enters the retroreflective member,
The polarized wave of the image light is converted to the other polarized wave by the image light passing through the retardation plate twice, and the converted image light passes through the reflective polarizing plate.
Spatial floating image display device.
The spatial floating image display device according to claim 25,
In the light source device, the contrast obtained by the characteristics of the two polarizing plates provided on the light incident surface and the light emitting surface of the image source is combined with the reciprocal of the polarization conversion efficiency in the polarization conversion means and the reflective polarized light. Contrast performance multiplied by the reciprocal of the cross transmittance of the plate,
Spatial floating image display device.