JP5665053B2 - Multi-viewpoint aerial image display device - Google Patents

Description

  The present invention relates to a multi-viewpoint aerial image display apparatus that forms a mirror image of a projection object as a real image floating in the air and allows observation from a plurality of viewpoints.

  The present inventor arranges a projection object on one side of a plane assumed in space, and has an optical function of forming a mirror image of the projection object as a real image in the opposite space with the plane as a symmetry plane. As an element (optical system), a reflection type real mirror image forming element (hereinafter referred to as a “two-sided corner reflector array” provided with a number of two-surface corner reflectors, which are real mirror image forming elements composed of two mirror surfaces. (Refer to Patent Document 1) and a real mirror image forming optical system (refer to Patent Document 2) using a retroreflector array having a retroreflection function and a half mirror.

  The two-surface corner reflector array disclosed in Patent Document 1 emits light emitted from an object to be projected (including an actual object and an image) disposed on one side of an element plane in the two-surface corner reflector array. The two-surface corner reflector array is reflected while being reflected by each of the two mirror surfaces, thereby forming a mirror image of the projection object as a real image in the space on the observation side, which is the other side of the element plane. It has an imaging mode. Such a two-sided corner reflector array is based on reflection of light by a mirror surface, but is an imaging element that functions as a transmission type as an element, for example, a plurality of two-sided corner reflectors in one element plane. By devising the arrangement in various directions, it is possible to construct a real mirror image imaging optical system that can form aerial images that can be observed simultaneously from various directions by a large number of people. (See Patent Document 3). In addition, the real mirror image forming optical system of Patent Document 2 effectively combines the property of a retroreflector that reflects light in the direction in which the light is incident and the property of a half mirror that reflects and transmits the light. In addition, the image forming apparatus has a novel imaging mode that enables observation of an aerial image from a wide viewing angle.

Table 2007-116639 JP2009-025776 Table 2008-111426

  By the way, in the conventional mirror image forming optical system as in Patent Documents 1 and 3, when the projection object is a stereoscopic image, the real image obtained by the optical system is a mirror image viewed from the back side. become. Further, in the two-surface corner reflector array of Patent Document 1, the viewing angle is limited, and an aerial image that can be observed from multiple viewpoints cannot be displayed as it is. Therefore, the viewing angle in the left-right direction can be increased by devising the arrangement of the two-surface corner reflectors configured as shown in Patent Document 3, but the depth inversion remains the same. Further, in the retroreflector type real mirror image forming optical system of Patent Document 2, it is possible to take a wide viewing angle as it is, but the depth is also reversed.

  Therefore, the present invention utilizes the property of the optical element or optical system that forms an image on a plane-symmetrical position in the above-described conventional example, and suppresses the occurrence of stray light, while the projection of an object to be projected from a plurality of viewpoints with time differences. The main purpose is to provide a novel optical system that enables image observation.

That is, the multi-viewpoint aerial image display device according to the present invention is capable of forming an actual image of a projection object using a reflection of light rays at a plane symmetrical position with respect to a predetermined geometric plane as a symmetry plane. An optical system, and a rotating means for rotating the whole or part of the real mirror image forming optical system on the symmetry plane about the normal of the symmetry plane as an axis . A visual field control means for blocking or diffusing only a light beam in a predetermined angle range is provided in part or all .

  Here, as a specific aspect of the rotating means, for example, an appropriate means can be adopted as long as the object can be rotated, such as a belt, a gear, a roller, or a combination of these. . In the present invention, one or a plurality of real mirror image forming optical systems can be used. A two-dimensional or three-dimensional object or video can be applied to the projection object. For example, if a plurality of stereoscopic images (projected objects) whose depths are inverted in advance are arranged on one side of the symmetry plane, a stereoscopic aerial image having a normal depth can be observed on the observation side (real image side). Become. In addition, since the projection object and its image are in a relationship in which the top and bottom are reversed, it is desirable that the projection object is reversed upside down in advance. As an example, for example, when an image projected on the inner surface of a hemispherical cup hollowed out inside is inverted as an object to be projected, on the observation side, on the outer peripheral surface of a virtual hemispherical cup. It is possible to observe the “real image of the projection object” as an image that appears.

  In such a multi-viewpoint aerial image display apparatus of the present invention, assuming that the rotating means is not operated, the light emitted from the projection object is reflected by the real mirror image imaging optical system using reflection. Mirror image imaging optical system This real mirror image can be observed only from the viewpoint where the real image is imaged and fixed at a plane-symmetrical position with respect to the symmetry plane. When the whole or a part of the optical system is rotated within the plane of symmetry, the position at which the aerial image can be observed is sequentially changed depending on the time difference, and the image can be observed from many viewpoints. In addition, by adjusting the positional relationship between the real mirror imaging optical system and the projection object, even if rotation occurs, an image is formed in one narrow area in the air, so that the same position can be obtained from any viewpoint. An aerial image can be observed.

  As one specific example of the multi-viewpoint aerial image display apparatus as described above, a real mirror image forming optical system is a two-surface corner reflector composed of two mirror surfaces perpendicular to each other perpendicular to a predetermined element plane. A two-sided corner reflector array in which a plurality of are arranged on the element plane, and the element plane is the symmetry plane.

  In this case, when the light from the projection passes through each element plane, it is reflected once by the two mirror surfaces of each two-sided corner reflector and formed as a real image in the air on the opposite side of the element plane. That is, the observer can observe a real image of the projection object formed by reflection with a two-surface corner reflector in which the internal angles of the two mirror surfaces face the line-of-sight direction. If the two-surface corner reflectors that make up one two-surface corner reflector array all face the same direction, the aerial image can be observed from one viewpoint when the two-surface corner reflector array is stationary. If the dihedral corner reflectors constituting the reflector array are directed in a plurality of directions, aerial images can be observed from a plurality of viewpoints simultaneously. Further, since the two-surface corner reflector array constituting the real mirror image forming optical system is directed in various directions by the rotating means, it is possible to observe the aerial image from multiple viewpoints with a time difference. Here, when the set of two-surface corner reflectors rotates in a plane parallel to the element plane, the twice-reflected light from the two-surface corner reflectors is retroreflected in the element plane, and therefore the light reflection direction is influenced by the rotation. The position of the image of the projection image formed at the plane-symmetric position of the projection object with respect to the element plane does not change. On the other hand, since the imaging position of the once reflected light changes with rotation, the stray light due to the once reflected light is averaged in the rotation direction. That is, since the influence of stray light is reduced at each viewpoint accompanying rotation, a clear image can be observed. When attention is paid to a certain viewpoint position, images of the projection object facing in various directions in time division can be observed from this position.

  As a more specifically preferable configuration of such a multi-viewpoint aerial image display device provided with such a two-sided corner reflector array, first, one two-sided corner reflector array is provided, and the rotating means is provided with the two-sided corner reflector array. One that can rotate the whole with the normal of the element plane as an axis can be mentioned. In this case, if all the two-surface corner reflectors are oriented in the same direction, the image forming position and the observation position of the projection object by one two-surface corner reflector array are one, and the two-surface corner reflectors are directed in a plurality of directions. If the two-sided corner reflector array is stationary, a plurality of observation positions are obtained. However, it is possible to perform observation from multiple viewpoints at a time difference or simultaneously by rotation.

  Further, as another preferred configuration, a plurality of two-surface corner reflector arrays having element planes on the same plane are provided, and the rotation means individually or entirely with respect to each element plane normal axis as an axis There is one that rotates in synchronization. In this case, one observation position is generated for each two-sided corner reflector array. Therefore, by rotating these individually or simultaneously, it is possible to observe an aerial image from multiple viewpoints at the same time. In addition, the number of times the aerial image can be observed from the same viewpoint can be increased.

  As another preferred configuration, one or more two-sided corner reflector arrays are provided, and the rotating means is an individual two-sided corner reflector constituting the two-sided corner reflector array or a plurality of two sides in a certain area. The set of corner reflectors may be rotated about the normal of the element plane. With such a configuration, more viewpoints can be set with rotation.

  Here, considering the two-surface corner reflector, in order to transmit the light through the element plane while appropriately bending the light beam in the two-surface corner reflector, the two-surface corner reflector is optically assumed to pass through the element plane. It can be considered that the inner wall of the hole is used as a mirror surface. However, such a two-surface corner reflector is a conceptual object and does not necessarily reflect the shape determined by a physical boundary or the like. For example, the optical holes are not made independent of each other. It can be connected.

  To simply describe the structure of the dihedral corner reflector array, a large number of mirror surfaces substantially perpendicular to the element plane are arranged on the element plane. The problem as a structure is how to support and fix the mirror surface on the element plane. As a more specific method of forming a mirror surface, for example, a two-sided corner reflector array is provided with a base that partitions a predetermined space, and one plane passing through the base is defined as an element plane, and a two-sided corner reflector is provided. As an optical hole assumed in the direction penetrating the element plane, the inner wall of the hole formed in the substrate can be used as a mirror surface. The hole formed in the substrate only needs to be transparent so that light can pass therethrough, and for example, the inside may be filled with a vacuum or a transparent gas or liquid. Also, the shape of the hole may be any shape as long as the inner wall has one or more mirror surfaces not acting on the same plane for acting as a unit optical element, and the light reflected by the mirror surface can pass through the holes. It is possible to take a complicated shape in which each hole is connected or a part of the hole is missing. For example, an aspect in which individual mirror surfaces stand on the surface of the base can be understood as connecting holes formed in the base.

  Alternatively, the two-surface corner reflector may use a cylindrical body formed of a solid such as transparent glass or resin as an optical hole. In addition, when each cylindrical body is formed of solid, these cylindrical bodies may be brought into close contact with each other and serve as a support member for the element, and project from the surface of the base as having a base. You may take the aspect which did. As for the shape of the cylindrical body, as long as the inner wall has one or more mirror surfaces not included in the same plane for acting as a two-surface corner reflector, and the light reflected by the mirror surface can pass through the cylindrical body It is possible to take any shape, and although it is referred to as a cylindrical body, it may be a complicated shape in which each cylindrical body is connected or partly missing.

  Here, as the optical hole, a shape in which the adjacent inner wall surfaces are all orthogonal, such as a cube or a rectangular parallelepiped, can be considered. In this case, the distance between the two-surface corner reflectors can be minimized, and a high-density arrangement is possible. Further, if all the inner wall surfaces are mirror surfaces, four sets of two-surface corner reflectors facing different directions can be formed in one hole, and the two-surface corner reflector as an imaging element that can be observed from various directions. An array can be constructed. However, the presence of parallel and opposing mirror surfaces increases the possibility of unwanted multiple reflections.

  When there are a plurality of mirror surfaces in the two-sided corner reflector, there is a possibility that there is multiple reflected transmitted light that causes reflection more than the expected number of times. As a countermeasure against this multiple reflection, when two mirror surfaces orthogonal to each other are formed on the inner wall of the optical hole, the surfaces other than these two mirror surfaces are made non-mirror surfaces so that light is not reflected, By providing an angle or providing a curved surface so as not to be vertical, it is possible to reduce or eliminate multiple reflected light that causes three or more reflections. In order to obtain a non-mirror surface, it is possible to employ a configuration in which the surface is covered with an antireflection coating or a thin film, or a configuration in which the surface roughness is roughened to cause irregular reflection. In addition, since the presence of a transparent and flat substrate does not hinder the function of the optical element, the substrate can be arbitrarily used as a support member / protective member.

  Furthermore, in order to achieve a high definition of the image of the projection object, it is desirable to arrange a plurality of two-sided corner reflectors on the element plane as far as possible from each other, for example, in a grid pattern. It is. Further, in this case, there is an advantage that manufacture is also facilitated.

  As a mirror surface in a two-sided corner reflector, regardless of whether it is solid or liquid, it reflects on a flat surface formed of a glossy substance such as metal or resin, or between transparent media having different refractive indexes. A material that reflects or totally reflects on a flat boundary surface can be used. Further, when the mirror surface is configured by total reflection, undesired multiple reflection by a plurality of mirror surfaces is likely to exceed the critical angle of total reflection, so that it can be expected to be naturally suppressed.

  The mirror surface may be formed on a very small part of the inner wall of the optical hole as long as there is no functional problem, or may be constituted by a plurality of unit mirror surfaces arranged in parallel. In other words, the latter aspect means that one mirror surface may be divided into a plurality of unit mirror surfaces. In this case, the unit mirror surfaces do not necessarily have to be on the same plane as long as they are parallel to each other. Further, each unit mirror surface is allowed to be either in contact with or apart from each other. In the case of configuring a two-surface corner reflector array, a two-surface corner reflector with two orthogonal mirror surfaces is required, and thus two orthogonal mirror surfaces must be formed in one unit optical element. The two mirror surfaces that are orthogonal to each other are not necessarily in contact with each other. When light is transmitted from one side of the element plane to the other side, it is only necessary to reflect the two mirror surfaces once. Either a mode in which the mirror surfaces are in contact with each other or a mode in which they are separated is allowed.

  As an example of a specific embodiment of the present invention other than an embodiment using a two-surface corner reflector array, as a real mirror image forming optical system, a retroreflector array that retroreflects light rays and a half mirror that reflects and transmits light rays A half mirror having a surface, and with the half mirror surface as a symmetrical surface, the retroreflector array surrounds the projection object together with the half mirror on the same side as the projection object with respect to the half mirror. It can also be mentioned that the rotating means rotates at least the retroreflector array about the normal line of the half mirror surface as an axis. Here, “retroreflection”, which is the action of the retroreflector, refers to a phenomenon in which the reflected light is reflected (reversely reflected) in the direction in which the incident light is incident. The incident light and the reflected light are parallel and opposite to each other. Become. Such a retroreflector arranged in an array is a retroreflector array, and when the individual retroreflectors are sufficiently small, the paths of incident light and reflected light can be regarded as overlapping. In this retroreflector array, the retroreflectors do not need to be on the same plane, and the retroreflectors may be three-dimensionally scattered. The half mirror refers to a mirror having both a function of transmitting light and a function of reflecting light, and preferably has a transmittance and a reflectance of approximately 1: 1.

  As the retro reflector, one composed of three adjacent mirror surfaces (which can be called a “corner reflector” in a broad sense) or a cat's eye retro reflector can be used. The corner reflector includes a corner reflector composed of three mirror surfaces orthogonal to each other, two of the angles formed by the three adjacent mirror surfaces are 90 degrees, and the other angle is 90 / N degrees (N May be an acute angle retroreflector or the like in which the angles formed by the three mirror surfaces are 90 degrees, 60 degrees, and 45 degrees.

  In the case of a multi-viewpoint aerial image display device using such a retroreflector array and a half mirror, the light emitted from the projection object is reflected by the half mirror surface, and then retroreflected by the retroreflector array to make sure that it is in the original direction. Returning and imaging through the half mirror surface, the shape and position of the retroreflector array is not limited as long as the reflected light from the half mirror is received. And the observation of the formed real image can be observed from the direction opposite to the light beam transmitted through the half mirror surface, and the retroreflector array rotates around the normal line of the half mirror surface. The aerial image can be observed from a plurality of viewpoints.

  Further, in the multi-viewpoint aerial image display device of the present invention as described above, a field of view that blocks or diffuses only light rays in a predetermined angle range on a part or all of the symmetry plane in the real mirror image forming optical system. By providing the control means, only the aerial image can be observed from the intended direction, and the projection object can be prevented from being directly viewed through the symmetry plane. In addition, as a visual field control means, a visual field control film can be used, for example, and it is good to stick this visual field control film to a part of the two-surface corner reflector array or the half mirror which constitutes a symmetrical plane.

  Furthermore, in the multi-viewpoint aerial image display device of the present invention, as the projection object, an image displayed on the display surface of the display is employed, and volume scanning is performed on the display so that the display surface fills a predetermined three-dimensional space. Type stereoscopic display. The display surface of the display may be flat or curved, but when using a volume scanning type stereoscopic display in this way, the display surface moves by a real mirror image forming optical system based on the image displayed on the display surface. The three-dimensional image can be observed from a plurality of viewpoints as a real mirror image with a time difference.

  According to the multi-viewpoint aerial image display apparatus of the present invention, when the whole or a part of the real mirror image imaging optical system on the target surface is rotated in the symmetry plane by the rotating means, the aerial image formed by the time difference is observed. Since the position changes sequentially, it is possible to observe a clear image of the projection object from many viewpoints while suppressing the influence of stray light by using a simple means of rotation.

1 is a plan view schematically showing a multi-viewpoint aerial image display device of the present invention. D1-d1 sectional drawing in FIG. The perspective view which shows schematically the 2 surface corner reflector array applied to the embodiment, and its image formation mode. The top view which shows the 2 surface corner reflector array applied to the embodiment. The perspective view which expands and shows a part of the 2nd surface corner reflector array. The top view which shows typically the image formation style by the multiview aerial image display apparatus of the embodiment. FIG. 6 is a plan view schematically showing a modification of the multi-viewpoint aerial image display device according to the embodiment. The perspective view which shows typically the image formation style in the modification. FIG. 6 is a plan view schematically showing a modification of the multi-viewpoint aerial image display device according to the embodiment with the rotating means omitted. The top view which shows the 2 surface corner reflector array applied to the modification. The top view which shows the example of a combination structure of the 2 surface corner reflector array applied to the modification. FIG. 10 is a plan view schematically showing another modification of the multi-viewpoint aerial image display device according to the embodiment with the rotating means omitted. The perspective view which expands and shows a part of other example of the 2 surface corner reflector array applied to 1st Embodiment. FIG. 10 is a plan view schematically showing a modification of the multi-viewpoint aerial image display device according to the second embodiment with the rotating means omitted. The schematic front view which expands and shows a part of retro reflector array applied to the embodiment. The typical perspective view which shows the reflective aspect of the light ray in the corner cube which comprises the retro-reflector array.

  Embodiments of the present invention will be described below with reference to the drawings.

  First Embodiment A multi-viewpoint aerial image display device 3A1 according to a first embodiment of the present invention forms a large number of two-surface corner reflectors 1 on one element plane S as shown in FIGS. The two-surface corner reflector array 2A is provided, and the projection object O is arranged on one surface side (the lower surface side in the illustrated example) of the two-surface corner reflector array 2A. Is further provided in the element plane S with a rotation means 4 that rotates the normal of the element plane S as the rotation axis l. In this embodiment, in order to enable observation of an aerial image of the projection object O only from a certain direction and to limit observation from a direction different from the intended direction, on the upper surface side of the two-surface corner reflector array 2A, A line-of-sight control means 24 is provided.

  As shown in FIG. 3, when the dihedral corner reflector array 2A is stationary, a mirror image of the projection object O is formed as a real image at a plane symmetric position with respect to the element plane S when observed from the viewpoint V. So this is what you can see. Since the two-sided corner reflector 1 is very small compared to the whole of the two-sided corner reflector array 2A, the entire set of the two-sided corner reflectors 1 is shown in gray in FIG. 1 and FIG. Is represented in a V-shape. Hereinafter, the specific configuration and imaging mode of each part will be described.

  As shown in FIG. 4, the two-sided corner reflector array 2 </ b> A includes a flat plate-like base 21, and a plurality of square holes 22 penetrating the wall thickness perpendicular to the flat base surface are formed on the base 21. In order to use the inner wall surface of each hole 22 as the two-surface corner reflector 1, the mirror surfaces 11 and 12 are formed on two of the inner wall surfaces of the hole 22 that are orthogonal to each other.

  The base 21 is a thin plate having a thickness of 50 to 200 μm, for example, 100 μm in the present embodiment. In this embodiment, a base having a square shape with a side of about 5 cm is applied. The thickness and planar dimensions of 21 can be appropriately set without being limited to these. As shown in FIG. 5 by enlarging part A of FIG. 4, each two-sided corner reflector 1 is formed by using physical and optical holes 22 formed in the base 21 to transmit light. It is. In the present embodiment, first, a large number of holes 22 having a substantially square shape in plan view are formed in the base 21, and two inner wall surfaces that are adjacent and orthogonal to each other are subjected to smooth mirror surface treatment to form mirror surfaces 11 and 12. The mirror surfaces 11 and 12 are the two-surface corner reflector 1 that functions as a reflection surface. In addition, it is preferable to suppress a part of the inner wall surface of the hole 22 other than the two-surface corner reflector 1 from being subjected to mirror surface treatment so that light cannot be reflected, or to prevent multiple reflected light by providing an angle. . Each two-surface corner reflector 1 is formed on the base 21 so that the inner angles formed by the mirror surfaces 11 and 12 are all in the same direction. Hereinafter, the direction of the inner angle of the mirror surfaces 11 and 12 may be referred to as the direction (direction) of the dihedral corner reflector 1. In forming the mirror surfaces 11 and 12, in the present embodiment, a metal mold is first created, and the inner wall surface on which the mirror surfaces 11 and 12 are to be formed is subjected to nanoscale cutting processing to form the mirror surfaces. The surface roughness is 10 nm or less, and the surface is uniformly mirrored with respect to the visible light spectrum region.

  Specifically, each of the mirror surfaces 11 and 12 constituting each two-sided corner reflector 1 has a side of 50 to 200 μm, for example, 100 μm corresponding to the thickness of the base 21 in the present embodiment. A plurality of the substrate 21 is formed at a predetermined pitch by a nanoimprint method or an electroforming method in which the press method used is applied to the nanoscale. In the present embodiment, each side that forms a V shape on the element plane S of each two-sided corner reflector 1 is inclined 45 degrees with respect to the width direction or depth direction of the base 21, and all the two-sided corner reflectors 1 are arranged. Are aligned on regular lattice points assumed on the element plane S and face the same direction. In addition, the transmittance | permeability can be improved by setting the separation | spacing dimension of adjacent 2 surface corner reflectors 1 as small as possible. In addition, a portion of the base 21 other than the portion where the two-surface corner reflector 1 is formed is subjected to a light shielding process, and a transparent reinforcing material having a thin plate shape (not shown) is provided on the upper and lower surfaces of the base 21. In the present embodiment, a two-surface corner reflector array 2A in which tens of thousands to hundreds of thousands of such two-surface corner reflectors 1 are provided on the base 21 is employed.

  As another mirror surface forming method, when the base 21 is formed of a metal such as aluminum or nickel by an electroforming method, the mirror surfaces 11 and 12 naturally become mirror surfaces if the surface roughness of the mold is sufficiently small. . When the substrate 21 is made of resin or the like using the nanoimprint method, it is necessary to perform mirror coating by sputtering or the like in order to create the mirror surfaces 11 and 12.

  The double-sided corner reflector 1 formed on the base 21 in this way reflects light entering the hole 22 from the front surface side (or back surface side) of the base 21 by one mirror surface (11 or 12) and further reflects the reflected light. Is reflected by the other mirror surface (12 or 11) and passed to the back surface side (or front surface side) of the base 21, and when this light path is viewed from the side, the light entrance path and the light exit path Is symmetrical with respect to the base 21, so that a large number of two-face corner reflectors 1 are formed on the base 21 as described above to function as the two-face corner reflector array 2A. That is, the element plane S (assuming a plane that passes through the central portion of the thickness of the base 21 and is orthogonal to each mirror surface, and is indicated by an imaginary line in FIG. 5) of the two-sided corner reflector array 2A is one side of the base 21. A mirror image of the projection object O on the side becomes a surface that forms a real image P (hereinafter referred to as “real mirror image P” as necessary) at a plane symmetrical position on the other side.

  The multi-viewpoint aerial image display device 3A1 is configured such that the projection object O is arranged on the lower surface side of the above-described two-surface corner reflector array 2A. As shown in FIGS. 1 and 2, the rotating means 4 provided in the multi-viewpoint aerial image display device 3A1 has a disk shape supporting the end of the base 21 of the two-sided corner reflector array 2A and a rectangular shape in the center. A support part 41 provided with a hole 411, a disk-like drive part (not shown) that rotates around an axis parallel to the central axis of the support part 41, a peripheral part of the support part 41, and a peripheral part of the drive part An annular belt part 42 suspended from the part, and the base 21 supported by the support part 41 is rotated by transmitting the rotational movement of the drive part to the support part 41 via the belt part 42. Thus, the entire element plane S is rotated in a plane parallel to the element plane S. In the present embodiment, when the belt portion 42 is rotated in the direction indicated by the arrow x in FIG. 1 by rotating the drive portion, the support portion 41 is moved in the horizontal plane by the arrow y in FIG. 1 according to the rotation of the belt portion 42. As a result, the entire element plane S rotates in the horizontal plane. In addition, although the rotational speed of 2 A corner reflector array 2A is constant (for example, 1800 rpm), it is good also as other speeds, and it does not necessarily need to be constant. Further, the entire element plane S is continuously rotated, but may be intermittently rotated. In addition, a configuration in which the base 21 itself is rotated by the drive unit and the belt part 42 without using the base 21 and the support part 41 as separate members may be employed. In addition, although the illustrated example shows a state in which the two-surface corner reflector array 2A is rotated counterclockwise in plan view by the rotating means 4, the rotation direction is not particularly limited.

  Further, the observation of the real mirror image P of the projection object O through the two-surface corner reflector array 2A rotated by the rotation device 4 by the line-of-sight control means 24 provided on the upper surface side of the two-surface corner reflector array 2A is constant at the same time. This is possible only from the direction of (a certain angle range). More specifically, the line-of-sight control means 24 (shown in a broken-line frame in FIG. 1 and shown in a broken line in FIG. 2) allows a light beam in a certain angle range to pass and a light beam in another angle range. Is a structure in which a plate material having a large number of slits arranged so as to be cut off (hereinafter referred to as “slit plate”) is attached to the base 21, and light beams in other angular ranges are allowed to pass through only a certain angle range. For example, an optical film such as a visibility control film or a viewing angle adjusting film having a function of blocking or diffusing (for example, a trade name “Lumisty” (manufactured by Sumitomo Chemical Co., Ltd.)) is attached to the base 21. By providing such a line-of-sight control means 24, the light emitted from the projection object O travels only in the direction of the viewpoint V of the observer, as indicated by the one-dot chain line in FIG. It does not advance in the direction of (in the figure, x mark).

  Next, an aspect of imaging the real mirror image P of the projection object O using the multi-viewpoint aerial image display device 3A1 of the present embodiment will be described together with a path of light emitted from the projection object O. For convenience of explanation, the case where the rotating unit 4 is operated and the case where it is not operated will be described separately.

(1) When the rotating means 4 is not operated As shown in the schematic plan view of FIG. 6, light emitted from the projection object O (indicated by the arrow direction and solid line. Three-dimensionally, from the back side of the drawing to the front of the drawing. Is reflected by one mirror surface 11 (or 12) constituting the two-surface corner reflector 1 when passing through the hole 22 formed in the base 21 of the two-surface corner reflector array 2A By reflecting on the mirror surface 12 (or 11) (the light ray of the transmitted light is indicated by a broken line), as shown in the schematic perspective view in FIG. 3, the projection is performed on the element plane S of the two-surface corner reflector array 2A. An image is formed as a real mirror image P showing the letter “F” at the plane symmetry position of the object O. The real mirror image P can be viewed by observing the mirror surfaces 11 and 12 of the two-sided corner reflector of the two-sided corner reflector array 2A, that is, the viewpoint V obliquely above the base 21. More specifically, when the light is reflected once twice with respect to the mirror surfaces 11 and 12 that are orthogonal to each other, a total of the light components that are parallel to the surface direction of the substrate 21 (in other words, the element plane). The component parallel to S) returns to the incident direction, while the component parallel to the surface direction of the mirror surfaces 11 and 12 (in other words, the component perpendicular to the element plane S) preserves that component. As a result, the twice reflected light that has passed through the two-surface corner reflector array 2A always passes through a point that is plane-symmetric with respect to the element plane S. Since light in all directions is emitted from the projection object O, which is a light source, when the light passes through the two-surface corner reflector array 2A, it is reflected twice by each two-surface corner reflector 1, and all the same points. Get together and focus. In this way, the twice reflected light that has passed through the two-surface corner reflector array 2A is focused on a plane-symmetrical position, so that it is focused in a wide range with respect to the depth direction (direction perpendicular to the element plane S). Is possible. When a three-dimensional object is arranged as the projection object O in the space on the lower surface side of the base 21, a three-dimensional image is floated on the upper surface side of the base 21. However, the unevenness is reversed in the three-dimensional image. Of the light emitted from the projection object O, the light that does not reflect on the mirror surface 11 or the mirror surface 12 but directly passes through the hole 22 is blocked or diffused by the line-of-sight control means 24, so that it is a two-surface corner reflector. The projection object O cannot be directly visually recognized through the array 2A.

(2) When the rotating means 4 is operated When the rotating means 4 is operated, the entire two-surface corner reflector array 2A is continuously at a constant speed in a plane parallel to the element plane S (in the horizontal plane). Rotate. At this time, since the twice reflected light by the two-surface corner reflector 1 is retroreflected in the element plane S, the reflection direction of the light beam is not affected by the rotation, and the object O is plane-symmetric with respect to the element plane S. The location of the real mirror image P of the projection imaged at the position does not change. On the other hand, since the imaging position of the once reflected light changes with rotation, the stray light due to the once reflected light is averaged in the rotation direction. That is, since the influence of stray light is reduced at each viewpoint associated with the rotation, a clear real mirror image P can be observed. Then, the viewpoint that is at a position facing the two-surface corner reflector 1 sequentially rotates in the rotation direction according to the rotation by the rotation means of the two-surface corner reflector array 2A. That is, the real mirror image P can be observed from any direction above the element plane S as long as the point of view facing the two-corner reflector 1 in a time-sharing manner is the viewpoint. Even when the two-sided corner reflector array 2A is rotated in this way, the light that directly passes through the hole 22 without being reflected by the mirror surface 11 or the mirror surface 12 is blocked or diffused by the line-of-sight control means 24, and the two-sided corner reflector. The projection object O cannot be directly visually recognized through the array 2A.

  Thus, in the multi-viewpoint aerial image display device 3A1 of the present embodiment, a simple method of rotating the entire two-surface corner reflector array 2A in a plane parallel to the element plane S by the rotating means 4. However, it is possible to observe the clear real mirror image P of the projection object from multiple viewpoints while suppressing the influence of stray light.

  <Modification of First Embodiment> The present embodiment using the two-surface corner reflector 1 is not limited to the above-described aspect. For example, although the rotation means 4 is configured using the belt portion 42, the configuration of the rotation means 4 can be appropriately changed according to the embodiment, such as a configuration using gears or rollers. Further, a holding part (not shown) for holding the two-surface corner reflector 1 on the element plane S may be provided, and the holding part may be rotated by a rotating means. With such a configuration, each two-sided corner reflector 1 can be independently rotated by the rotating means via the holding portion. Therefore, it is possible to individually control the stray light caused by the one-time reflected light of each of the two-surface corner reflectors 1 to effectively reduce the influence of the stray light and observe a clear mirror image P. Furthermore, a holding part (not shown) for holding a set of a plurality of two-sided corner reflectors 1 in a certain region on the element plane S may be provided, and this holding part may be rotated by a rotating means. With such a configuration, a set of a plurality of two-sided corner reflectors 1 in a certain region can be independently rotated by the rotating means via the holding unit. Therefore, the stray light caused by the one-time reflected light for each set of the plurality of two-surface corner reflectors 1 in each region is individually controlled to effectively reduce the influence of the stray light, and the clear mirror image P is observed. It becomes possible.

  In addition to the above, a plurality of two-surface corner reflector arrays 2A may be provided. For example, the multi-viewpoint aerial image display device 3A2 shown in FIG. 7 uses two (2A1, 2A2) two-sided corner reflector arrays 2A described above, and these two-sided corner reflector arrays 2A1, 2A2 are used as the respective two-sided corners. The element planes S and S are configured to be on the same plane so that the reflectors 1 face each other. Then, at the joint portion between the two-sided corner reflector arrays 2A1 and 2A2, the projection object O is arranged at the center of one side of the element plane S (the lower side of the base 21), so that this multi-viewpoint aerial image is obtained. When the display device 3A2 is stationary, the real mirror image P1 of the object O1 is projected from the viewpoint V1 through the one two-surface corner reflector array 2A1 and from the viewpoint V2 through the other two-surface corner reflector array 2A2. P2 can be observed. In this example, the rotating means for supporting the end portions of the two-surface corner reflector arrays 2A1 and 2A2 and rotating the entire multi-viewpoint aerial image display device 3A2 in a plane parallel to the element plane S as in the above-described embodiment. By providing 4 (see FIGS. 1 and 2), the two viewpoints in which the real mirror image P can be seen corresponding to the rotation are sequentially rotated. In this example shown in FIG. 7 and each example (FIGS. 8 to 12) described later, the line-of-sight control means 24 is provided on the upper surface side of the two-sided corner reflector array as in the first embodiment described above. Thus, only the real mirror image corresponding to each viewpoint is observed without directly viewing the projection object O through the two-surface corner reflector array from any viewpoint.

  In other words, while the entire multi-viewpoint aerial image display device 3A2 is rotated by the rotation means 4, the real mirror image P can always be observed from two viewpoints. In addition, since the direction of the projection object O which becomes the origin of the real mirror image P imaged by the two-surface corner reflector arrays 2A1 and 2A2 differs depending on the viewpoint to be observed, the appearance of the real mirror image P is different. For example, as schematically shown in FIG. 8 in the image formation mode by the two-surface corner reflector arrays 2A1 and 2A2, the letter “F” as the projection object O is changed from the viewpoint V1 by one of the two-surface corner reflector arrays 2A1. Although the image is formed in the correct direction and observed, the back side of the letter “F” that is the projection object O is imaged by the two-surface corner reflector array 2A from the opposite viewpoint V2, and the letter “F” is formed. An image with the inside out is observed.

  Furthermore, an aspect using three or more two-surface corner reflector arrays is also possible. For example, the multi-viewpoint aerial video display device 3A3 shown in FIG. 9 (rotating means is not shown) prepares six two-sided corner reflector arrays 2A similar to those used in the first embodiment, and cuts them in half. One of them is newly formed as a two-sided corner reflector array 2A3, which is configured by changing the orientation and rejoining so that each element plane S exists on one common plane. Specifically, as shown in FIG. 10, each of the two-surface corner reflector arrays 2A3 is formed by inclining the direction of the two-surface corner reflector 1 in the two-surface corner reflector array 2A used in the first embodiment by 45 ° in the element plane S. The formed two-surface corner reflector array 2A3 ′ is divided into two trapezoidal shapes by a straight line passing through the center of the element and intersecting the side edge at an angle of 60 °, and one of them (upper left half in the illustrated example) is a two-surface corner reflector. Array 2A3 is used. That is, of the six trapezoidal two-sided corner reflector arrays 2A3, three are turned upside down, and the ones that are turned upside down and the ones that are not turned upside down are joined so that the long sides of the trapezoids are adjacent to each other. Thus, a multi-viewpoint aerial video display device 3A3 including a plurality of two-sided corner reflector arrays 2A3 as shown in FIG. 9 is obtained. As shown in FIG. 11, in the two two-surface corner reflector array 2A3 in which the oblique sides of the trapezoid are joined, the directions of the two-surface corner reflectors 1 and 1 on the element plane S are slightly different, but generally one direction. Facing. By preparing three sets of two two-sided corner reflector arrays 2A3 obtained in this way and joining the edges of all the two-sided corner reflector arrays 2A3 so that the element plane S is flush with each other, The multi-viewpoint aerial video display device 3A3 of this example is obtained. This multi-viewpoint aerial image display device 3A3 does not cut the square two-surface corner reflector array 2A3 ′, but instead has a two-surface corner reflector array that has the same trapezoidal shape as the two-surface corner reflector array 2A3 from the beginning. Needless to say, it can also be formed by using six sheets.

  In the multi-viewpoint aerial image display device 3A3 obtained in this way, the projection object O is arranged in the center of the space on the one surface side (the back side of the paper surface) of the two-surface corner reflector array 2A3 in groups of two. Then, from the observation side which is the other surface side (above the paper surface), the real mirror images P1, P2 and P3 can be simultaneously observed at the plane-symmetrical positions with respect to the respective element planes S of the respective projection objects O. As a result of the rotation, the three viewpoints V1, V2, and V3 sequentially move in a plane parallel to the element plane S. More specifically, in the two two-surface corner reflector arrays 2A3 and 2A3 in which the oblique sides of the trapezoid are joined as described above, the two-surface corner reflector 1 faces the viewpoint (for example, the viewpoint V1) in substantially the same direction. 11 (see FIG. 11), as shown in FIG. 9, a set of these two sets is obtained by observing from the extension direction (viewpoint V1) of the hypotenuse of the trapezoid across the center of the multi-viewpoint aerial image display device 3A3. An image of the projection object O1 by the two-surface corner reflector arrays 2A3 and 2A3 can be confirmed. Since there are three combinations of the two-surface corner reflector arrays 2A3 and 2A3 facing in the same direction as described above in the multi-viewpoint aerial image display device 3A3 of the present embodiment, at least three directions (V1, V2, and V3) are used. The multi-view aerial image display device 3A3 always has a real mirror from six directions if the two-surface corner reflectors 1 of the six two-surface corner reflector arrays 3A3. The image P can be observed. However, two sets of two-surface corner reflector arrays 2A3 and 2A3 each have a displacement of about 15 ° with respect to the direction of the line of sight, rather than the two-surface corner reflectors 1 pointing exactly in the same direction. However, such a difference in angle is within the range of parallax between the eyes of the observer, and can be regarded as facing substantially the same direction.

  Note that, in the central portion of the multi-viewpoint aerial image display device 3A3, which is directly above the base 21 of the projection object O, when there are a large number of two-surface corner reflectors 1 facing different directions, the rotating means 4 is not operating. Since there is a high possibility that stray light is generated and the image is not clearly formed in the stationary state, the two-surface corner reflector 1 is not formed in a portion overlapping the projection object O on the base 21 when viewed in plan, and the stray light is made opaque. However, during the operation of the rotating means 4, stray light is unlikely to occur as described above, so it is not necessary to consider it.

  In addition to the above, for example, as shown in a schematic plan view in FIG. 12, a multi-viewpoint aerial image display device 3A4 (rotating means is not shown) having viewpoints in four directions at the same time can be configured. . The multi-viewpoint aerial image display device 3A4 is composed of a two-plane corner reflector array 2A4 having four planar fan shapes. The two-sided corner reflector array 2A4 has the same shape and the same size, each having a central angle of 90 °. In such a two-surface corner reflector array 2A4, the two-surface corner reflector 1 is formed in the same manner as in the first embodiment, and the two-surface corner reflector 1 of each two-surface corner reflector array 2A4 has its center. As in the case of the above-described modification, the two-surface corner reflector 1 may not be formed in the vicinity of the central angle so as to prevent stray light when stationary. In the case of this example, the four viewpoints V1, V2, V3, and V4 are planes parallel to the element plane S by rotating the multi-viewpoint aerial image display device 3A4 all at once by rotating means (not shown). Will move in sequence.

  In addition, in the multi-viewpoint aerial image display device provided with a plurality of two-sided corner reflector arrays as in the above-described various modifications, a mode in which the entire multi-viewpoint aerial image display device is rotated is shown. It is also possible to configure the arrays to be spaced apart and rotated individually or synchronously.

  Further, the two-surface corner reflector constituting the two-surface corner reflector array only needs to have two orthogonal reflecting surfaces, and this reflecting surface includes a mirror surface accuracy flatness of a material that reflects light such as metal. It is possible to use phenomena such as reflection by an end face or film having a thickness, and total reflection at a boundary having a mirror surface accuracy flatness between transparent media having different refractive indexes.

  More specifically, for example, in the above-described embodiment, in the two-surface corner reflector array, a square-shaped hole 22 is formed in the thin plate-shaped base 21, and two surfaces are formed by two adjacent inner peripheral walls of the hole. Although the corner reflector is formed, instead of such a configuration, as shown in an enlarged view in FIG. 13, a two-sided corner reflector is provided on each of the transparent rectangular parallelepiped cylindrical bodies 23 protruding in the thickness direction of the base 21. It is also possible to form a two-surface corner reflector array in which a large number of such cylindrical bodies 23 are formed in a grid pattern. In this case, the two-surface corner reflector 1 ′ can be formed also by an aspect in which two orthogonal surfaces among the inner wall surfaces of each cylindrical body 23 are mirror surface elements 11 ′ and 12 ′. In this case, similarly to the above-described embodiment, the light reflected twice by the two-surface corner reflector 1 ′ passes through a point that is plane-symmetric with respect to the surface direction of the base 21, that is, the element plane S. Can form not only a two-dimensional image but also a three-dimensional image in a space opposite to the element plane S.

  It should be noted that the inner wall surface other than the mirror surface elements 11 ′ and 12 ′ of the cylindrical body 23 is not a mirror surface, or an angle other than perpendicular to the element plane S ′ is provided, thereby eliminating excessive reflection and making it clearer. A good image can be obtained. The two mirror surfaces 11 ′ and 12 ′ constituting the two-surface corner reflector 1 ′ can use total reflection or can use reflection by a reflection film. In particular, when the total reflection of the mirror surfaces 11 ′ and 12 ′ is used, it can be expected that multiple reflections are less likely to occur because there is a critical angle for total reflection. Furthermore, it is also possible to attach a metal reflection film to two surfaces of a cylindrical body on which a mirror surface is to be formed, and bond the cylindrical bodies to each other. In this case, it is necessary to take measures against multiple reflections such as non-specularization to a surface other than the mirror surface, but a two-surface corner reflector array having a high aperture ratio and a high transmittance can be obtained.

  In addition, regarding a projection object, an object or an image can be appropriately applied regardless of whether it is two-dimensional or three-dimensional. For example, an image (either a still image or a moving image) displayed on the display surface of a flat display or a curved display can be used as the projection object. Furthermore, as such a display, a volume scanning type stereoscopic display in which the display operates so that the display surface fills the three-dimensional space may be adopted. In this case, a volume scanning three-dimensional display can be realized by operating the display including the display surface with a driving mechanism or driving device having an appropriate configuration using, for example, a motor, a spring, a gear, a gear, a rail, or the like. is there.

  In addition, the two mirror surfaces constituting the two-surface corner reflector may be arranged with a gap between each other without being in contact with each other as long as two orthogonal reflecting surfaces can be formed. The specific configuration of each part is not limited to the above-described embodiments and modifications, such as the configuration of the apparatus or the two-sided corner reflector array can be freely set, and various modifications can be made without departing from the spirit of the present invention. is there.

  Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. 14, FIG. 15, and FIG. The multi-viewpoint aerial image display device 3B according to the present embodiment applies a real mirror image forming optical system 2B using a half mirror 5 and a retroreflector array 6. As shown in FIG. 14, the real mirror image forming optical system 2B applied in the present embodiment is arranged in a space on one side of the half mirror surface 41 with the half mirror surface 51 of the half mirror 5 as a symmetry plane S ′. The light emitted from the projected object O is reflected by the half mirror surface 51, is further retroreflected by the retroreflector array 6, returns to the incident direction, and is transmitted through the half mirror surface 51. A mirror image is formed as a real image P at a plane symmetric position with respect to the half mirror surface 51 as the symmetry plane S ′, and a real mirror image imaging optical system 2B including a retroreflector array 6 in addition to such a configuration. Rotating means (not shown) is provided for rotating in the direction of the arrow in the drawing, with the normal line of the half mirror surface 51 that is the entire symmetry plane S ′ as the rotation axis l ′.

  In this embodiment, the half mirror 5 which is a constituent element of the real mirror image forming optical system 2B is obtained by coating a thin reflective film on one surface of a transparent thin plate such as a disk-shaped transparent resin or glass. Can be used. By applying anti-reflection treatment (AR coating) to the opposite surface of the transparent thin plate, it is possible to prevent the observed real mirror image P from being doubled. Note that a visual field control film or a viewing angle is provided on the upper surface of the half mirror 5 as a line-of-sight control means that transmits a light beam in a specific direction and blocks a light beam in another specific direction or diffuses only a light beam in a specific direction. An optical film 52 such as an adjustment film can be attached and provided. For such an optical film 52, the film applied in the first embodiment and its modifications can be applied. In addition to this, as a line-of-sight control means, a slit plate (not shown) in which a large number of slits are formed can be provided on the upper surface side of the half mirror 5. Specifically, the optical film 52 prevents light that has been emitted from the projection object O and directly transmitted through the half mirror 5 from reaching a position other than the viewpoint V1 ′, so that the viewpoint other than the viewpoint V1 ′ is transmitted through the half mirror 5. The projection object O is prevented from being directly observable on the other hand, while only being reflected by the half mirror 5 described later and retroreflected by the retroreflector array 6 and then transmitting only the light beam in the direction that passes through the half mirror 5. By doing so, only the real mirror image P, which is a set of real images of the projection object O, can be observed from a specific viewpoint (viewpoint V1 ′ in FIG. 14A and viewpoint V2 ′ in FIG. 14B) at a certain moment. ing. In the present embodiment, such an optical film 52 is attached to a semicircular region that is a half of the upper surface of the disk-shaped half mirror 5. Further, in the present embodiment, a light shielding film 53 that does not transmit light is attached to the half mirror 5 corresponding to a semicircular region where the optical film 52 is not attached. In addition, it may replace with the light shielding film 53 and may arrange | position the light shielding plate of the same shape. Although not shown, a transparent protective plate can be provided so that the observer's hand does not touch the rotating half mirror 5.

  On the other hand, the retroreflector array 6 may be one that retroreflects light rays with a mirror surface of smoothness on the surface, or retroreflects incident light by applying a retroreflective film or a retroreflective coating to the material surface. Any type can be applied, and it may be a curved surface as shown in FIG. 14 or a flat surface. In the present embodiment shown in the figure, the retroreflector array 6 having a curved surface has a large number of corner cubes (described later) formed on the inner surface side of a part of a sphere (1/4 sphere). For example, the retroreflector array 6 shown in FIG. 15 (a) in which a part of the front view is enlarged is a corner cube array that is a set of corner cubes using one corner of a rectangular parallelepiped. Each retroreflector 61 forms a regular triangle when the mirror surfaces 61a, 61b, and 61c forming three isosceles triangles of the same shape and the same size are gathered at one point and viewed from the front. 61a, 61b, 61c are orthogonal to each other to form a corner cube. Then, as shown in FIG. 16A, light incident on one of the mirror surfaces (for example, 61a) is sequentially reflected on the other mirror surfaces (61b, 61c), so that the light enters the retroreflector 61. Reflect in the original direction (retroreflection). 15B is a corner cube array that is a set of corner cubes that use one corner of the rectangular parallelepiped. Each retroreflector 61 forms a regular hexagon when the mirror surfaces 61a, 61b, 61c forming three squares of the same shape and the same size are gathered at one point and viewed from the front, and these three mirror surfaces 61a, 61b and 61c are orthogonal to each other. The retroreflector array 6 is different from the retroreflector array 6 in FIG. 6A only in the shape and the principle of retroreflection is the same. Similarly, as shown in FIG. The light incident on one (for example, 61a) is sequentially reflected on the other mirror surfaces (61b, 61c), and is reflected (retroreflected) in the original direction in which the light has entered the retroreflector 61. . The paths of the incident light and the outgoing light with respect to the retroreflector array 6 are not strictly overlapping but are parallel to each other. However, when the retroreflector 61 is sufficiently smaller than the retroreflector array 6, the paths of the incident light and the outgoing light. May be considered as overlapping. The retroreflector array 6 as described above can be produced by, for example, mirror finishing by cutting a metal plate such as aluminum or nickel, or an electroforming method on a metal plate or a resin plate. The difference between these two types of corner cube arrays is that the mirror surface is isosceles triangle is relatively easy to create, but the reflectivity is slightly lower, and the mirror surface is square is slightly easier to create than the isosceles triangle. While difficult, it has a high reflectivity.

  In the case of the multi-viewpoint aerial image display device 3B having such a configuration, when the entire real image imaging optical system 2B including the half mirror 5 with the optical film 52 having the visibility control function and the light shielding film 53 is rotated, At a certain moment, as shown in FIG. 14A, at a position where the light emitted from the projection object O, reflected by the half mirror surface 51, retroreflected by the retroreflector array 6 and transmitted through the half mirror 5 again can be seen. From a certain viewpoint V1 ′, it is possible to observe a real mirror image P formed at a plane symmetrical position with respect to the half mirror surface 51 which is the element plane S ′ of the projection object O. At another moment, as shown in FIG. 5B, the light emitted from the projection object O, reflected by the half mirror surface 51, retroreflected by the retroreflector array 6, and transmitted through the half mirror 5 again. From the viewpoint V2 ′, which is the visible position, the real mirror image P formed at a plane-symmetrical position with respect to the half mirror surface 51 that is the element plane S ′ of the projection object O can be observed. In this way, since the position where the real mirror image P can be observed moves sequentially as the half mirror 5 rotates, the real mirror image P can be observed from a plurality of viewpoints in a time difference in the space on the upper surface side of the half mirror 5. It becomes.

  In addition to the corner cube array described above, a retroreflector array 6 that retroreflects light rays with three mirror surfaces (“corner reflector” in a broad sense) can be employed. Although not shown, for example, as a unit retroreflective element, two mirror surfaces of three mirror surfaces are orthogonal to each other, and another mirror surface is 90 / N degrees with respect to the other two mirror surfaces (where N is an integer) And acute angle retroreflectors having angles of 90 degrees, 60 degrees, and 45 degrees formed by the adjacent mirror surfaces of the three mirror surfaces are suitable as the retroreflective element 3 applied to the present embodiment. In addition, a cat's eye retro reflector or the like can be used as a unit retroreflective element. These retro-reflector arrays may be planar or bent or curved. Further, in the example of FIG. 14, the ¼ spherical retroreflector array 6 is arranged outside the projection object O. However, the light emitted from the projection object O and reflected by the half mirror 4 can be retroreflected. As long as the position and shape can be achieved, the arrangement position and shape of the retroreflector array 6 can be set as appropriate.

  Furthermore, when the two-surface corner reflector array is applied in the present invention, in addition to the two-surface corner reflector array (2A and the like) shown in the first embodiment and the like, it has mirror surfaces that are perpendicular to the element surface and parallel to each other. A two-surface corner reflector array having a structure in which two slit mirror arrays are vertically stacked so that the mirror surfaces are vertical can also be employed.

  Further, the multi-viewpoint aerial image display device is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention, such as the specific configuration and shape of the half mirror and the retroreflector array, It is also useful to provide a light shielding part as mentioned in the first embodiment in the space on the projection object side of the element plane. Further, the multi-viewpoint aerial video display device may be configured so that observation from three or more viewpoints is possible. Furthermore, it is the same as in the case of the first embodiment that an image displayed on the display surface of the display can be adopted as the projection object, and that the display can be a volume scanning stereoscopic display.

DESCRIPTION OF SYMBOLS 1,1 '... 2 side corner reflector 2A, 2A1, 2A2, 2B, 2B1 ... 2 side corner reflector array 3A1, 3A2, 3A3, 3B ... Multi-viewpoint aerial image display device 4 ... Rotating means 5 ... Half mirror 6 ... Retro reflector Array 11, 11 ', 12, 12' ... mirror surface 21, 21 '... base 22 ... hole 23 ... cylindrical body 24 ... gaze control means 24
DESCRIPTION OF SYMBOLS 41 ... Support part 42 ... Belt part 411 ... Hole 51 ... Half mirror surface 52 ... Optical film 53 ... Light-shielding film 61 ... Retroreflector O ... Projection object P ... Mirror image (image of projection object)
S, S '... element plane l, l' ... rotation axis

Claims (4)

A real mirror image forming optical system capable of forming a real image of a projection object at a plane symmetrical position with respect to a predetermined geometric plane as a symmetry plane by using reflection of light, and the real mirror image on the symmetry plane Rotating means for rotating the whole or a part of the imaging optical system around the normal of the symmetry plane ;
A multi-viewpoint aerial image display device characterized in that a visual field control means for blocking or diffusing only a light beam in a predetermined angle range is provided on a part or all of a symmetry plane in the real mirror image forming optical system . The real mirror image forming optical system is a two-surface corner reflector array in which a plurality of two-surface corner reflectors composed of two mirror surfaces perpendicular to each other perpendicular to a predetermined element plane are arranged on the element plane. The multi-viewpoint aerial image display device according to claim 1, wherein an element plane is the symmetry plane. The real mirror image forming optical system includes one dihedral corner reflector array, and the rotating means rotates the dihedral corner reflector array as a whole with the normal of the element plane as an axis. Item 3. The multi-viewpoint aerial image display device according to Item 2. 4. The volume scanning type three-dimensional display according to claim 1 , wherein the projection object is an image displayed on a display surface of a display, and the display surface is a volume scanning type three-dimensional display that performs an operation of filling a predetermined three-dimensional space . The multi-viewpoint aerial video display device described in 1.

Images