JP2009288696A - Optical system, head-mounted projector, and retro-transmitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new optical system, a head-mounted projector and a retro-transmitting element that make a screen unnecessary by converting a real image into a virtual image although a projector for forming a real image is used. <P>SOLUTION: The optical system includes a projector 20 and a retro-transmitting element 13 disposed opposing to the projector 20, and subjects the incident light as not forming a real image from the projector 20 to retro-transmission through the retro-transmitting element 13 so as to form a virtual image by the retro-transmitted light in the opposite side to the incident face of the retro-transmitting element 13. The observer can observe the retro-transmitted beams by the retro-transmitting element 13 as a virtual image. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical system, a head-mounted projector, and a retrotransmissive element.

  In general, the optical elements can be divided into refractive optical systems and reflective optical systems except for special ones such as hologram optical elements. Even when devising the structure of an optical system or when designing a detailed design using simulation, the refractive optical system and the reflective optical system are used as basic elements, and a theoretical system is established around them. Various optical devices have been proposed by combining basic elements of the system and the reflection optical system alone or in combination. In other words, what is limited to these two systems is the greatest restriction when an optical system is assembled.

  In the refracting optical system, so-called optical elements are arranged in a line and light is passed in order, and the traveling direction of the light does not change. The reflective optical system can change the traveling direction of light. After determining the operating principle, it is the structural design of the optical apparatus to combine these two types and determine an arrangement in which elements do not interfere with each other in space.

In addition, the following nonpatent literature 1 is well-known as a technique regarding this application.
Maekawa, Nita, Matoba, "Symmetric imaging optical element using a micro dihedral corner reflector array-" Mirror "that forms a real image", Technical Report of the Information Media Society, Information Media Society of Japan, 30 (52), October 18, 2006, Vol.30, No.52, p.49-52

  As in the case of a machine, the space is a major limitation, and even if the operating principle of the optical apparatus is determined, there are cases where it is impossible to arrange the optical elements. In order to solve and alleviate this, a beam splitter composed of a half mirror or a prism is often used. An example will be described below.

  Since the head mounted projector (HMD) can project an image by placing the projector 10 at the viewpoint position 12 and can project an image, the observed image is not distorted regardless of the curved surface. Convenient (see FIG. 15). However, because the projector 10 and the viewpoint interfere with each other, the exit pupil of the projector 10 cannot actually be placed at the viewpoint position 12 as shown in FIG. 15, but the eye (the observation viewpoint A in FIG. ) If the beam splitter 16 is placed in front, the space is eliminated. A head-mounted projector arranged in this way is conventionally known.

  Here, the beam splitter 16, that is, a mirror having transparency such as a half mirror, is folded back. Since the projector 10 overlaps the human pupil (that is, the observation viewpoint A) in the folded space, the operation principle as described above is satisfied. Even in this case, it is necessary to devise the arrangement. For example, FIG. 17 has the same operating principle as that of FIG. 16, but the projector 10 blocks the light path to the screen 14, and thus a complete real image cannot be observed.

  In the case of an optical system having a conventional projector, not only a screen is required, but also the installation location of the screen needs to be taken into consideration. Therefore, in an optical system using a projector, there is an optical system that does not require a screen. It has been demanded.

An object of the present invention is to provide a novel optical system that can convert a virtual image and eliminate the need for a screen, even though a projector for forming a real image is used.
A second object of the present invention is to provide a novel head-mounted projector capable of converting a virtual image and eliminating the need for a screen, even though a projector for forming a real image is used. is there.

  Furthermore, a third object of the present invention is to provide a retrotransmissive element that can be suitably used in an optical system that can eliminate the need for a screen despite having the projector as described above. is there.

  In order to achieve the above object, the invention described in claim 1 is a projector and an element disposed opposite to the projector, and the incident light is directed to a surface opposite to the incident surface of the element. An element having a property of transmitting the light in such a manner that the light is changed in an axially symmetric direction with respect to the retrotransmission axis (hereinafter referred to as a retrotransmission element), and incident light of an unreal image from the projector is retroreflective. The gist of the optical system is that a virtual image is formed by the retroreflected light on the side opposite to the incident surface of the retrotransmissive element.

  An unreal image means the following. When the light beam projected from the projector is set so that the image formation position of the real image is beyond the surface on which the light beam is incident (the side beyond the surface opposite to the incident surface), The light beam incident on the surface is “not yet a real image”, that is, less than the real image. An intersection bundle that is less than this real image is called an “unreal image”.

  In addition, the retrotransmission axis means the following. The light rays incident on the retrotransmissive material pass through the material, but the emitted light is axially symmetric with respect to the incident light as compared to the case without the retrotransmissive material. This axis is called a retro-transmission axis. For example, in the case of the structure using the retroreflective element 32 and the planar beam splitter (semi-reflective layer 40) as shown in FIGS. 4 to 6, the normal line G of the beam splitter becomes the retrotransmission axis. If the beam splitter is a semi-transparent curved mirror, the normal of the curved shape is the retro-transmission axis at each position. Further, even when the curved mirror is miniaturized to form a Fresnel reflector, the normal line of each reflector is the retrotransmission axis. In the case of a structure using orthogonal dihedral mirrors (corner mirrors) as shown in FIGS. 7 to 8, the intersection line is the retrotransmission axis. In the case of the orthogonal dihedral mirror, as shown in FIG. 13, the optical effect similar to that of the curved mirror can be created by changing the arrangement of the retro-transmission axes depending on the location.

  And according to said structure, a projector injects a light beam (unreal image) into a retrotransmissive element. The group of rays that were converging toward the real image position is spread apart by this retrotransmission element, but the light travels in the direction opposite to the incident surface of the retrotransmission element. And the direction of the light does not change. On the contrary, since the angle for convergence is an angle for spreading, these ray bundles form a virtual image. The virtual image and the original real image are at the position of the surface object with respect to the retro-transmission surface. In other words, the retrotransmissive element does not change the traveling direction of the light bundle even though the space is folded and the real image is converted into the virtual image, so that light can enter the observation pupil and the image can be observed. .

The beam splitter 16 mentioned in the background art is the same in that the space is folded back, but is different from the retrotransmissive element in that it changes the traveling direction of the light beam.
In addition, it is preferable that all the optical systems in this embodiment consist of reflective elements.

The invention of claim 2 is characterized in that, in claim 1, the retrotransmissive element is curved so as to have a curved surface.
According to a third aspect of the present invention, the optical system according to the first or second aspect is provided on a support that is mounted on a user's head, and a virtual image is transmitted to the support by the retroreflected light. The head-mounted projector is characterized in that the retro-transmissive element is arranged so that the user can see it with the eyes of the user.

  The invention of claim 4 has a transparent layer and one surface of the transparent layer, or a semi-reflective layer provided inside the transparent layer, and the other side opposite to the one surface of the transparent layer. The gist of the present invention is a retrotransmissive element in which a large number of retroreflective elements that reflect light rays toward the semi-reflective layer are discretely arranged on the surface or inside the transparent layer.

The invention of claim 5 is characterized in that, in claim 4, the semi-reflective layer is curved.
The invention according to claim 6 is the retroreflective element according to claim 5, wherein the semi-reflective layer is curved in a concave shape, a reflective surface of the semi-reflective layer is formed as a concave mirror, and passes through the semi-reflective layer. The reflected light beam is reflected by the reflecting surface, passes through the transparent layer, and exits to the outside.

  The invention of claim 7 is the invention according to claim 5, wherein the semi-reflective layer is curved into a convex shape, the reflective surface of the semi-reflective layer is formed on a convex mirror, and the light rays incident on the transparent layer are reflected on the reflective surface. It is reflected, further reflected by the retroreflective element, passes through the semi-reflective layer, and goes outside.

  In the invention of claim 8, the plurality of voids are arranged in a dotted line shape and a circular shape with respect to the plate-shaped element body, and the plurality of void groups are concentrically formed. The gist of the retrotransmissive element is that it is arranged and the wall surface of the gap is formed in a mirror surface.

  According to the ninth aspect of the present invention, a plurality of gaps having different diameters are formed concentrically on a plate-like element body, and a wall surface of the gap is formed on a mirror surface. The gist of the present invention is a retro-transparent element characterized in that at least one end of the element is closed.

The invention of claim 10 is characterized in that, in claim 8 or claim 9, the gap is a through hole.
In the invention of claim 11, a large number of gaps are randomly arranged in the thickness direction of the element body with respect to the plate-like element body, and the inner surface of the gap has first and second mirror surfaces orthogonal to each other. A retrotransmissible element comprising: a two-surface orthogonal alignment mirror composed of: and a line of intersection of the first mirror surface and the second mirror surface arranged in a thickness direction of the element body. It is a summary.

The invention of claim 12 is characterized in that, in claim 11, the gap is a through hole.
A thirteenth aspect of the present invention is that, in the eleventh or twelfth aspect, the plate-shaped element body has a curved surface, and a line of intersection of the two-plane orthogonal alignment mirrors extends along a normal direction of the curved surface. It is arranged.

  A fourteenth aspect of the present invention is the method according to any one of the eleventh to thirteenth aspects, wherein a two-plane orthogonal alignment mirror is disposed on the plate-shaped element body, and a retro-transmission axis is set according to the location. Thus, in addition to retrotransparency, optical characteristics of light spreading or convergence are added.

Here, “folding” regarding the mirror, the retroreflective element, and the element having the retrotransmissive property (hereinafter referred to as the retrotransmissive device) will be described.
(Space wrapping)
The mirror folds the space symmetrically with respect to the mirror surface. This is because the light beam incident on the mirror is folded back in the normal direction of the mirror surface of the mirror. Both the real object in front of the mirror and the real image projected by the projector are observed as a virtual image on the other side of the mirror. A virtual image that can be observed from the mirror side is observed as a virtual image on the other side of the mirror.

  On the other hand, the retroreflective element forms, as a real image, a light bundle coming out of an object and a projected real image at the same position as the original, although the mirror is folded in the normal direction as in the mirror. However, retroreflection differs from a mirror in that in-plane folding, that is, the progress of light in a plane direction perpendicular to the normal direction of the incident surface of the retroreflective element is also folded. Even when the in-plane folding is performed, the space is folded back, so that the space is not folded back as a result of the folding of the space twice.

  This “in-plane folding” is to change the beam bundle that concentrates toward imaging into a divergent beam bundle like light emitted from the image point, and conversely, the divergent beam bundle emitted from the object or image point. This is accompanied by the effect of focusing and forming an image.

Here, the presence or absence of “in-plane folding” and “folding in the normal H direction” in the transparent plate 10, the mirror 11, the retroreflective element 12, and the retrotransmissive element 13 is shown in FIG.
In-plane folding refers to folding in the traveling direction of light in a plane direction perpendicular to the normal H direction of the incident surface. Further, the normal H direction means a normal direction on the incident surface of each member.

  In FIG. 1, “× (+1)” indicates no return and “× (−1)” indicates return. In the transparent plate 10, the mirror 11, the retroreflective element 12, and the retrotransmissive element 13 in each frame shown in FIG. 1, (a), (b), and (c) are perspective views of each member, It is a top view and a side view, and the advancing direction when the light ray K is each irradiated to each member is shown. In FIG. 1, the black circles shown in (b) indicate the incident point of the light ray K on each member.

(Row, Column) = (1, 1) is the transparent plate 10 that is not folded in the normal direction or in the plane.
(Row, column) = (1, −1) is the mirror 11. The mirror has folding (simple reflection) in the normal H direction and no in-plane folding. As a result, the real image becomes a virtual image.

  (Row, Column) = (− 1, −1) is the retroreflective element 12. Since the retroreflective element 12 is folded in the normal H direction and folded in the plane, as a result, since the concentrated light and the diffused light are converted without folding the space, the real image is formed again at the same position. The virtual image that can be observed from the retroreflective element 12 side forms a real image at the virtual image position.

  The remaining one frame, that is, (row, column) = (− 1, 1) is the retrotransmissive element 13. As shown in FIGS. 1 and 2, the retrotransmissive element 13 does not fold in the normal H direction, but only folds in the plane.

(Real image to virtual image conversion)
Here, when the image formation position of the real image is set to the other side of the surface on which the light beam is incident (the side beyond the surface opposite to the incident surface), the light incident on the surface Since the bundle is “not yet a real image”, that is, less than the real image, in the following, this bundle of rays is referred to as an “unreal image” for convenience of explanation.

In the case of the mirror 11, the unreal image is folded back on the incident surface (in this case, the mirror surface) to form a real image in front of the surface.
In the case of the retroreflective element 12 and the retrotransparent element 13, the unreal image forms a virtual image after being folded by exchanging the concentration and spreading by folding in the plane. In this way, the action of the unreal image resulting in a virtual image is hereinafter referred to as real image / virtual image conversion.

  In the case of the retroreflective element 12, the light flux of the unreal image travels in the reverse direction, and a virtual image is formed at the original position where the real image was present when there was no retroreflective element. Further, in the case of the retrotransmissive element 13, an unreal image light beam is folded back symmetrically with respect to a plane orthogonal to the normal line of the retrotransmissive element 13 to form a virtual image.

  According to the optical system of the first aspect, the non-real image (light bundle) can be converted into the real image / virtual image by the retro-transmission element in spite of the use of the projector for forming the real image. The observer can observe the reflected light as a virtual image, and can eliminate the need for a screen.

  According to the invention of claim 2, by being curved so as to have a curved surface, there is an effect of moving the focal position of the virtual image farther or nearer than when the virtual image is not curved, A narrow field of view can be obtained.

According to the head mounted projector of the third aspect, it is possible to convert the virtual image and eliminate the screen even though the projector for forming the real image is used.
According to the retrotransmissive element of the fourth aspect, the incident light is transmitted to the surface opposite to the incident surface of the element, and then emitted in a direction that is axially symmetric with respect to the retrotransmission axis (recursion). Transparency). As a result, the optical system having the configuration according to claim 1 or 2 and the head-mounted projector having the configuration according to claim 3 can be suitably employed.

  Further, the retrotransmissive element according to claim 4 does not change the traveling direction of the light in the sense that it turns the space, allows a part of the incident light beam to pass, and passes it to the side surface opposite to the incident surface. In addition, this is a new optical element that converts an unreal image (light beam) before image formation into a virtual image. As a result, a new element can be added as an element constituting the optical system determined by the permutation combination.

  According to the fifth aspect of the present invention, the semi-reflective layer is curved, so that the non-real image (light bundle) incident on the retrotransmissive element passes through the incident surface and the other side of the surface. When it passes, the effect of moving the focal position of the virtual image distally or proximally is obtained, and a wide field or a narrow field can be obtained.

  According to the invention of claim 6, the semi-reflective layer is curved in a concave shape, the reflective surface of the semi-reflective layer is formed in the concave mirror, and the light beam that has passed through the semi-reflective layer and is reflected by the retroreflective element is reflected. The effect of claim 5 can be realized by reflecting on the reflecting surface, passing through the transparent layer and going outside.

  According to the invention of claim 7, the semi-reflective layer is curved into a convex shape, the reflective surface of the semi-reflective layer is formed on the convex mirror, and the light incident on the transparent layer is reflected by the reflective surface, By reflecting with the retroreflective element and passing through the semi-reflective layer, the effect of claim 5 can be realized.

The retrotransmissive element according to any one of claims 8 to 14 can be suitably employed in the optical system having the configuration according to claim 1 or 2, and the head-mounted projector having the configuration according to claim 3.
Further, the retrotransmissive element according to any one of claims 8 to 14 turns the space, allows a part of the incident light beam to pass therethrough, and allows the light to travel to the side surface opposite to the incident surface. And a new optical element that converts an unreal image (light bundle) before image formation into a virtual image without changing. As a result, a new element can be added as an element constituting the optical system.

(First embodiment)
Hereinafter, an embodiment embodying the optical system of the present invention will be described with reference to FIGS. As shown in FIG. 3 (a), this optical system is a projector 20 and a flat retro-reflective element 13 that is opposed to the projector 20 and disposed before the position where the light beam projected by the projector 20 forms an image. It is composed of Further, the projector 20 is arranged such that the projection point 20a is optically conjugate with the observer's observation viewpoint A and does not enter the observer's field of view when viewed from the observation viewpoint A.

  The projector 20 originally connects the real image in the direction in which the real image is projected. However, since the retrotransmissive element 13 is disposed before the image formation position of the real image, the space is turned back and the real image virtual image conversion is performed. The light beam projected from the projector 20 can be observed from the observation viewpoint A as a virtual image on the projector 20 side of the retrotransmissive element 13.

  As shown in FIGS. 4A and 5A, the retrotransmissive element 13 includes a transparent solid layer 30 as a transparent layer formed in a flat plate shape, and one of the transparent solid layers 30. A large number of retroreflective elements 32 arranged discretely on the surface of the transparent solid layer 30 and a flat semi-reflective layer 40 formed of a half mirror as a beam splitter laminated on the other surface of the transparent solid layer 30. In the present embodiment, the normal line of the semi-reflective layer 40 (half mirror) is the retro-transmission axis G of the retro-transmission element 13. In this embodiment, the semi-reflective layer 40 is provided on the surface (that is, the boundary surface) with the transparent solid layer 30, but the semi-reflective layer 40 is provided inside the transparent solid layer 30. Also good.

For convenience of explanation, FIG. 4A shows the optical path of the light beam K, so that the configuration of the retrotransmissive element 13 is simplified.
The transparent solid layer 30 is made of a transparent material. In addition, although the transparent material of the transparent solid body layer 30 is not limited, For example, transparent plastics, such as an acrylic resin, or glass can be mentioned.

  In this embodiment, the retroreflective element 32 is composed of a corner cube prism. The corner cube prism is made of the same transparent material as the transparent solid layer 30 and has retroreflectivity. The size of the corner cube prism is not limited, but is preferably a minute size of mm units or micro units.

  The corner cube prism can be formed on the transparent solid layer 30 by a fine processing technique such as a known photolithography, LIGA using X-rays, or nanoimprint. A coating layer 33 made of a metal film such as aluminum vapor deposition is formed on the outer surface of the corner cube prism, and the total reflection of light is enhanced. The coating layer 33 may be formed of a silver vapor deposition film or a chromium vapor deposition film instead of the aluminum vapor deposition film.

  The accuracy of retroreflection by the retroreflective element 32 is the accuracy of retrotransmission as it is. Further, the arrangement of the retroreflective element 32 with respect to the transparent solid layer 30 is not limited and has a very high degree of freedom.

  As shown in FIG. 4A and FIG. 5A, a part of the light ray K (incident light) incident on the surface (incident surface) of the semi-reflective layer 40 is transmitted through the semi-reflective layer 40 and is transparent. It enters the layer 30 and is retroreflected by the reflective surface of the retroreflective element 32 (corner cube). A part of the retroreflected light beam K is further reflected by the semi-reflective layer 40, passes through the transparent solid layer 30, and between the retroreflective elements 32 and the incident surface of the retrotransmissive element 13. Go out from the opposite side.

  In the above description, the case where the light ray K is incident from the surface side of the semi-reflective layer 40 in FIG. 4A has been described. However, the property of the retrotransmissive element 13 is transparent as shown in FIG. When the light ray K is incident on the surface (incident surface) of the solid layer 30, the following occurs. For convenience of explanation, FIG. 4B shows the optical path of the light ray K, so that the configuration of the retrotransmissive element 13 is simplified. That is, the light ray K (incident light) incident between the retroreflective elements 32 of the transparent solid layer 30 passes through the transparent solid layer 30 and is partially reflected by the reflective surface of the semi-reflective layer 40 to be transparent. Retroreflection is performed by the retroreflective element 32 provided on the solid layer 30 side. Then, a part of the retroreflected light beam K passes through the transparent solid layer 30 and the semi-reflective layer 40 and goes outside. Accordingly, the surface of the retrotransmissive element 13 that faces the projector 20 may be on the transparent solid layer 30 side or the semi-reflective layer 40 side.

  In this way, the light ray K (incident light) projected from the projector 20 is folded back by the retroreflective element 32 and the semi-reflective layer 40 of the retrotransmissive element 13, that is, retroreflected and retroreflective. The reflected light is imaged on the side opposite to the incident surface of the element 13.

Now, the characteristics of the optical system of the present embodiment configured as described above and the retrotransmissive element 13 will be described.
(1) The optical system according to the present embodiment includes a projector 20 and a retrotransmissive element 13 disposed so as to face the projector 20, and the incident light of an unreal image from the projector 20 is converted into the retrotransmissive element 13. Thus, a virtual image is formed by the light retroreflected on the side opposite to the incident surface of the retrotransmissive element 13.

  As a result, an unreal image (light bundle) can be converted into a real image / virtual image by the retrotransmissive element 13 in spite of using the projector 20 for forming a real image. The observer can observe as a virtual image. As a result, a screen can be made unnecessary even though the projector is used.

  (2) The retrotransmissive element 13 of the present embodiment has a transparent solid layer 30 (transparent layer) and a semi-reflective layer 40 provided on one surface of the transparent solid layer 30, and the transparent solid layer A large number of retroreflective elements 32 that reflect light rays toward the semi-reflective layer 40 are discretely arranged on the other surface opposite to the one surface 30.

  With this configuration, the light (incident light) incident on the retrotransmissive element 13 is transmitted to the surface opposite to the incident surface, and then emitted in a direction that is axially symmetric with respect to the retrotransmission axis (recursion). Transparency). As a result, it can be suitably employed in the above-described optical system.

  As described above, the retrotransmissive element 13 according to the present embodiment turns back the space, passes a part of the incident light beam, and passes the light to the side surface opposite to the incident surface. It is a new optical element that does not change and converts an unreal image (light bundle) before image formation into a virtual image. As a result, a new element can be added as an element constituting the optical system.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. In the following embodiments including this embodiment, the same reference numerals are given to the same or corresponding components as those of the other embodiments described above, and the detailed description thereof will be omitted.

  In the first embodiment shown in FIG. 3A, the projector 20 is arranged at a position that does not enter the observer's field of view. However, there is no problem even if the projector 20 enters the observer's field of view. For example, as shown in FIG. 3B, even if the projector 20 enters the observer's field of view, the light flux projected from the projector 20 is converted into a real image / virtual image by the retrotransmissive element 13, and as a result, The observer can see a complete virtual image without any interruption of the light beam projected from the projector 20. This is because, for example, the projector 10 in FIG. 17 blocks the optical path to the screen 14, so that a completely virtual image that is not blocked is observed compared to the conventional example in which only an incomplete real image having the blocked portion can be observed. It can be seen that this embodiment, which can be performed, is more advantageous. In the example of FIG. 3B, the optical axis of the projector 20 and the observation viewpoint A of the observer are made to coincide with each other, but in actuality, the observer 20 is positioned coaxially with the pupil of the projector 20. The projector 20 is arranged so that the viewer does not feel dazzling. Although the projector 20 shown in FIG. 3B is shown large for convenience of explanation, in practice, a diameter of about the same level as a penlight is sufficient.

(Third embodiment)
Next, another embodiment of the retrotransmissive element 13 will be described with reference to FIGS. 7 and 8.
In the retrotransmissive element 13 of the present embodiment, minute through-holes 42 having right-angled triangular cross-sections as a plurality of voids are penetrated in the thickness direction of the element body 41 and randomly. Has been placed. The element body 41 may be a transparent body or a non-transparent body.

  On the inner surface of the through-hole 42, there is formed a two-surface orthogonal alignment mirror composed of a first mirror surface 44 and a second mirror surface 45 that are orthogonal to each other, as shown in FIG. Yes. The corner mirror 43 is formed by a surface mirror using the metal film described in the first embodiment.

  The line of intersection of the first mirror surface 44 and the second mirror surface 45 (that is, the retrotransmission axis G) is arranged in the thickness direction of the element body 41. In other words, the retrotransmission axis G is arranged orthogonal to the plane of the element body 41. The direction of the retrotransmission axis G coincides with the normal direction of the surface of the element body 41. The size of the through hole 42 is not limited, but is preferably a minute size of mm units or micro units.

  In the present embodiment, as shown in FIG. 8A, the light incident from one surface side of the element body 41 is reflected by the first mirror surface 44 and the second mirror surface 45 of the through hole 42 (or the second mirror surface). 45 and reflected by the first mirror surface 44) and exits from the other surface of the element body 41. FIG. 8B is an enlarged view of the through hole 42 of the element body 41 in plan view. As shown in FIG. 8B, the incident light beam is reflected as indicated by an arrow, and includes a corner mirror 43. The retrotransmissive element 13 exhibits retrotransparency.

The effects exhibited by this embodiment will be described below.
(1) In the retrotransmissive element 13 of the present embodiment, a large number of through holes 42 (voids) are randomly arranged in the thickness direction of the element body 41 with respect to the plate-like element body 41, and the inner surface of the through hole 42 Is formed with a corner mirror 43 (two-plane orthogonal alignment mirror) composed of a first mirror surface 44 and a second mirror surface 45 which are orthogonal to each other. Further, an intersection line between the first mirror surface 44 and the second mirror surface 45 is arranged in the thickness direction of the element body 41.

  As a result, the retrotransmissive element 13 does not change the traveling direction of the light in the sense that the retroreflective element 13 folds the space and passes a part of the incident light beam to the side surface opposite to the incident surface, and A new optical element that converts an unreal image (light bundle) before imaging into a virtual image can be obtained. As a result, a new element can be added as an element constituting the optical system.

  In addition, when the retrotransmissive element 13 of the present embodiment is employed in the optical system of the first embodiment, the through holes 42 are randomly arranged, which is compared with the case where the through holes 42 are not randomly arranged. Thus, the degree of freedom in the arrangement relationship between the projector 20 and the retrotransmissive element 13 is improved.

(Fourth embodiment)
Next, another embodiment of the retrotransmissive element 13 will be described with reference to FIGS.
In the retrotransmissive element 13 of the present embodiment, a plurality of gaps 50, that is, a plurality of gap groups 52 in which through holes are arranged in a dotted line shape and a circular shape with respect to a flat element body 41 are concentric. Arranged in a shape. And the wall surface 54 of the space | gap 50 is formed in the mirror surface. The size of the gap 50 is not limited, but is preferably a minute size of mm units or micro units. Moreover, it is preferable that the space | interval of adjacent space | gap group 52 is a mm unit or a micro unit. The mirror surface of the wall surface 54 is formed of a surface mirror using the metal film described in the first embodiment.

  In the optical system employing the retrotransmissive element 13 of the present embodiment, it is assumed that the light beam projected from the projector 20 passes through a small region such as the exit pupil of the projector 20 or the observation pupil of the observer. It is. For this purpose, both are arranged such that the optical axis of the projector 20 and the concentric axis of the gap group 52 are coaxial. In the present embodiment, the concentric axis of the gap group 52 is the retrotransmission axis G.

FIG. 9B is an enlarged cross-sectional view in which the gap 50 of the element body 41 is enlarged.
When the optical system is formed as described above, as shown in FIG. 9B, the light rays incident from one surface side of the element body 41 are arrows on the wall surface 54 (mirror surface) of each gap 50 in each gap group 52. As shown in FIG. 4, the light is reflected from the other surface of the element body 41 to the outside. In this way, the retrotransmissive element 13 exhibits retrotransparency.

  The retrotransmissive element 13 of the present embodiment also does not change the traveling direction of the light in the sense that the space is folded back and a part of the incident light beam is allowed to pass to the side surface opposite to the incident surface. This is a new optical element that converts an unreal image (light bundle) before image formation into a virtual image. As a result, a new element can be added as an element constituting the optical system determined by the permutation combination.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIGS. 10 (a) and 10 (b). This embodiment is a modification of the fourth embodiment. In the present embodiment, the element body 41 of the retrotransmissive element 13 is formed in a circular shape and a plurality of gaps 60 having different diameters are formed concentrically, and the wall surface 62 of the gap 60 is formed in a mirror surface. Has been. In addition, the mirror surface should just be formed in the wall surface 62 with a larger diameter among the wall surfaces which form each space | gap 60 at least.

  The width in the radial direction of the gap is not limited, but is preferably a minute size of mm units or micro units. Moreover, it is preferable that the space | interval of the adjacent space | gap 60 is a mm unit or a micro unit. The mirror surface of the wall surface 62 is formed of a surface mirror using the metal film described in the first embodiment. One opening end side of the gap 60 is closed by a transparent plate 64 laminated on the element body 41. In this embodiment, one open end of the gap 60 is closed by the transparent plate 64, but a pair of transparent plates are laminated so that the element body 41 is sandwiched between the two open ends positioned in the thickness direction of the gap 60. May be occluded.

  In the optical system that employs the retrotransmissive element 13 of the present embodiment, the light bundle projected from the projector 20 has a small area such as the exit pupil of the projector 20 or the observer's observation pupil as in the fourth embodiment. It is premised on passing. For this purpose, both are arranged such that the optical axis of the projector 20 and the concentric axis of the gap group 52 are coaxial.

FIG. 10B is an enlarged cross-sectional view in which the gap 60 of the element body 41 is enlarged.
When the optical system is formed as described above, as shown in FIG. 10B, the light beam incident from one surface side of the element body 41 is indicated by the arrow on the wall surface 62 (mirror surface) of each gap 60. It is reflected and goes out from the other surface of the element body 41 through the transparent plate 64. Thus, the retrotransmissive element 13 of the present embodiment exhibits retrotransparency. The operational effects of the retrotransmissive element 13 of the present embodiment are the same as those of the fourth embodiment.

(Sixth embodiment)
Next, a sixth embodiment will be described with reference to FIG. In the present embodiment, Claim 6 is embodied. In the present embodiment, any one of the retrotransmissive elements 13 described in FIGS. 5A, 5B, 6A, and 6B is curved, that is, the transparent solid layer 30. And the semi-reflective layer 40 are both curved. 11A and 11B, for convenience of explanation, a cross-sectional view of the retrotransmissive element 13 is shown in a simplified cross-sectional view as in FIGS. 4A and 4B.

  Specifically, the retrotransmissive element 13 of the present embodiment has a semi-reflective layer 40 disposed on the projector 20 side as shown in FIG. In the retrotransmissive element 13, the semi-reflective layer 40 and the transparent solid layer 30 are both curved toward the outside (that is, the projector 20 side). As a result, the reflective surface (that is, the mirror surface) of the semi-reflective layer 40 becomes concave and faces inward (observation viewpoint A side), and functions as a concave mirror.

  In this case, the light beam incident from the projector 20 is retroreflected by the retroreflective element 32, and then reflected by the reflective surface of the semi-reflective layer 40 functioning as a concave mirror. This concave mirror function moves the focal point of the virtual image distally, so that the observer sees the virtual image with a wide field of view.

  As the curved surface, it is possible to use a spherical surface, a rotating hyperboloid, a paraboloid, or the like that is easy to obtain optical conjugation between the exit pupil and the viewpoint entrance pupil of the projector 20. Since the curved surface in the present embodiment has an effect of moving the focal position to the distal (distant) position, the curvature is obtained in a region in which what enters the observation pupil of the observer is distributed among the intersection bundles constituting a certain pixel. Isotropic is preferable because the image formation is not disturbed.

  Thus, in this embodiment, since the transparent solid layer 30 and the semi-reflective layer 40 of the retro-transmissive element 13 are both curved in the same direction, some of the light rays that have passed through the semi-reflective layer 40 recur. When retroreflected by the reflective element 32, the retroreflected light beam is reflected by the reflecting surface (the concave mirror), passes through the transparent solid layer 30, and exits to the outside of the observation viewpoint A side. Yes.

  For this reason, the effect of moving the focal position of the virtual image distally when the unreal image (light beam) incident on the retrotransmissive element 13 passes through the incident surface and passes beyond the surface. There is a wide field of view.

(Seventh embodiment)
Next, a seventh embodiment will be described with reference to FIG. Note that the present embodiment is one in which claim 7 is embodied. Also in the present embodiment, any one of the retrotransmissive elements 13 described with reference to FIGS. 5A, 5 </ b> B, 6 </ b> A, and 6 </ b> B includes the transparent solid layer 30 and the semi-reflective layer 40. And are both curved.

  As the curved surface, it is possible to use a spherical surface, a rotating hyperboloid, a paraboloid, or the like that is easy to obtain optical conjugation between the exit pupil and the viewpoint entrance pupil of the projector 20. Since the curved surface in the present embodiment has an effect of moving the focal position far away, the curvature is isotropic in the region where what enters the observer's observation pupil is distributed among the intersection bundles constituting a certain pixel. It is preferable that the image formation is not disturbed.

  Specifically, the retrotransmissive element 13 of the present embodiment has a transparent solid layer 30 disposed on the projector 20 side as shown in FIG. In the retrotransmissive element 13, the semi-reflective layer 40 and the transparent solid layer 30 are both curved in a convex shape toward the projector 20, and the reflective surface of the semi-reflective layer 40 is formed as a convex mirror. Then, the optical system is formed in a state where the convex side of the retrotransmissive element 13 is arranged facing the projector 20.

  In this case, the light beam incident on the transparent solid layer 30 from the projector 20 is reflected by the reflecting surface, which is a convex mirror, and further retroreflected by the retroreflective element 32, and a part of the retroreflected light beam is semi-reflective layer 40. And go outside on the observation viewpoint A side.

Since the focal point of the virtual image is moved far away by this convex mirror function, the observer sees the virtual image with a wide field of view.
(Eighth embodiment)
Next, an eighth embodiment will be described with reference to FIGS. 14 (a) and 14 (b). This embodiment is an embodiment in which the optical system of the present invention is embodied in a head-mounted projector.

  As shown in FIG. 14A, the head mounted projector 100 is provided on the spectacle frame 110. The eyeglass frame 110 includes a pair of left and right rims 112 that support the pair of retrotransmissive elements 13, a bridge 114 that connects the rims 112, and a temple 118 that is attached to the rim 112 via a hinge 116. In addition, a projector 20 is attached to the front of each rim 112 (on the side viewed by the observer) via a bracket 120. The projector 20 is mounted at a position that is optically conjugate with the observer's observation viewpoint A across the retrotransmissive element 13 and at a position that does not enter the observer's field of view when viewed from the observation viewpoint A. (See FIG. 14B). In addition, although the structure of 6th Embodiment is employ | adopted for the retrotransmissive element 13 of this embodiment, of course, as a structure of the retrotransmissive element 13, the structure of the retrotransmissive element 13 of 7th Embodiment is used. Further, the configuration of another embodiment other than the sixth and seventh embodiments may be employed.

  As described above, the head mounted projector according to the present embodiment is configured such that the optical system is supported by the glasses frame 110 using the glasses frame 110 mounted on the user's head as a support. In this embodiment, the retrotransmissive element 13 is arranged on the spectacle frame 110 (support) so that a virtual image can be seen by the user's eyes by the retroreflected light.

As a result, the head-mounted projector 100 of the present embodiment can convert a virtual image and eliminate the need for a screen, even though a projector for forming a real image is used.
In addition, the said embodiment can also be changed and comprised as follows.

  In the embodiment shown in FIG. 5A, the corner cube prism is provided as the retroreflective element 32 on the surface of the transparent solid layer 30 of the retrotransmissive element 13, but the retroreflective element 32 has a corner. Instead of the cube, a large number of glass beads may be discretely formed on the transparent solid layer 30 so as to be partially embedded as shown in FIG. This glass bead preferably has a high light refractive index with a refractive index of around 2. A coating layer 33 is formed on the outer surface of the glass beads by vapor-depositing a metal thin film made of the same material as the metal thin film formed on the outer surface of the corner cube.

Even in this case, the glass beads retroreflect light rays in the same manner as the corner cube.
In the embodiment shown in FIG. 5 (a), the corner cube prism is provided as the retroreflective element 32 on the surface of the transparent solid layer 30 of the retrotransmissive element 13, but as shown in FIG. 6 (a). In addition, the entire corner cube prism may be embedded in the transparent solid layer 30.

  In addition, in the embodiment shown in FIG. 5B, discrete portions are formed by embedding some glass beads as retroreflective elements 32 on the surface of the transparent solid layer 30 of the retrotransmissive element 13. However, as shown in FIG. 6B, the entire glass beads may be embedded in the transparent solid layer 30.

  In the embodiment of FIGS. 4 and 5, instead of providing the transparent solid layer 30 as shown in FIG. 4C, the retroreflective element 32 is supported by a support member 70 formed in a lattice shape or a net shape. Thus, a gap layer 65 as a transparent layer may be formed between the retroreflective element 32 and the semi-reflective layer 40 (beam splitter). In this case, the gap member 65 is formed between the retroreflective element 32 and the semi-reflective layer 40 by providing a spacing member 80 between appropriate portions of the support member 70 and the semi-reflective layer 40. .

  In the retrotransmissive element 13 of the embodiment shown in FIG. 7, the cross-sectional shape of the through hole 42 is a right triangle, but it is only necessary to have a corner mirror on the inner surface of the through hole. The cross-sectional shape is not limited to a cross-sectional right-angled triangle, but may be a cross-sectional shape that is a square shape or a polygonal shape and that has at least two mirror surfaces orthogonal to each other.

  In the retrotransmissive element 13 of the embodiment shown in FIG. 7, the element body 41 is provided with a through hole 42 as a gap, but the gap is not limited to the through hole 42. It is good also as the space | gap which made the hole which plugged up the opening end, and closed both the opening ends of the through-hole with the transparent board, respectively. In any case, since the corner mirror is formed on the wall surface surrounding the gap, the same effects as in FIG. 7 can be obtained.

  In the sixth embodiment, the retrotransmissive element 13 is curved in order to obtain a wide field of view, but although not shown, a configuration opposite to that in FIG. 11A may be used to obtain a narrow field of view. In this case, the virtual image can be enlarged by moving the focal position of the virtual image proximally as compared with the case where the retrotransmissive element 13 is flat. Specifically, in the retrotransmissive element 13, the semi-reflective layer 40 is disposed on the projector 20 side, and both the semi-reflective layer 40 and the transparent solid layer 30 are on the opposite side from FIG. A curve is formed on the inner side (observation viewpoint A side). As a result, the reflective surface (that is, the mirror surface) of the semi-reflective layer 40 functions as a convex mirror.

  In the seventh embodiment, the retrotransmissive element 13 is curved in order to obtain a wide field of view. However, although not shown, a configuration opposite to that in FIG. In this case, the virtual image can be enlarged by moving the focal position of the virtual image proximally as compared with the case where the retrotransmissive element 13 is flat. Specifically, in the retrotransmissive element 13, the transparent solid layer 30 is disposed on the projector 20 side, and the semi-reflective layer 40 and the transparent solid layer 30 are on the opposite side of FIG. A curve is formed on the inner side (observation viewpoint A side). As a result, the reflective surface (that is, the mirror surface) of the semi-reflective layer 40 functions as a concave mirror.

  In the sixth and seventh embodiments, the mirror side may be further miniaturized using a Fresnel reflecting mirror (Fresnel semi-transmissive mirror 90) (see FIG. 13). In this case, the fine structure can be divided into a physical shape and a shape in an optical sense, so that the degree of freedom in design can be raised. That is, instead of using a curved mirror as the semi-reflective layer 40 as shown in FIGS. 11A and 11B, a Fresnel semi-transmissive mirror 90 may be provided as a semi-reflective layer (beam splitter) as shown in FIG. The same optical effect as when the semi-reflective layer 40 is curved, that is, spreading or convergence of light rays can be performed. In this case, the Fresnel semi-transmission mirror 90 has the refined annular zone surface 90a, and therefore has the respective retro-transmission axes G in the respective annular zone surfaces 90a that are directed in different directions.

  In the third embodiment shown in FIGS. 7 and 8, the intersection lines (recursive transmission axes G) of the corner mirrors 43 are arranged so as to be orthogonal to the plane of the element body 41 (see FIG. 12A). In this case, in the third embodiment, the space is simply folded as indicated by the arrows, as in the case of the plane mirror. In FIGS. 12A to 12C, the retrotransmissive element 13 is simply shown as a straight line or a curve for convenience of explanation.

  Instead of this configuration, that is, instead of the flat element body 41 of the third embodiment, the element body 41 may be formed to have a curved surface. In this case, as this curved surface, a spherical surface, a rotating hyperboloid, a paraboloid, or the like that can easily take an optical conjugate of the exit pupil and the viewpoint entrance pupil of the projector 20 can be used. As a result, as shown in FIG. 12B, for example, when the element body 41 has a spherical surface U as a curved surface, a light beam coming from the outside stands on the retrotransmission axis G perpendicular to the spherical surface U. It has an optical path as if it was reflected by the spherical surface U. Similarly, a light ray coming from the inside (from below in FIG. 12B) has an optical path as if it was reflected by the spherical surface U.

  As described above, the plurality of corner mirrors 43 (corner mirror array) arranged along the curved surface and having the retrotransmission axis G perpendicular to the curved surface, retroreflects the light incident on the retrotransmissive element 13. The light traveling direction is not changed in the sense that it passes through the thickness direction of the active element 13 and passes through the side surface opposite to the incident surface. Note that this direction of travel is the opposite of the curved mirror. In FIG. 12B, the arrow indicated by a dotted line indicates the reflection direction of the light beam reflected by the curved surface in the case of the curved mirror.

  Further, in the retrotransmissive element 13, although not shown in FIG. 12C, the corner mirror 43 provided in the retrotransmissive element 13 is not related to the shape of the incident surface of the retrotransmissive element 13. That is, regardless of whether the incident surface is a flat surface or a curved surface, the direction in which the retrotransmission axis G faces may be set to an arbitrary direction. In this case, as with the Fresnel lens and the reflecting mirror, it is possible to separate the physical shape from the optical meaning.

  In the eighth embodiment, the support for supporting the optical system is the spectacle frame 110, but the support is not limited to the spectacle frame 110, and the helmet is used as a support to the retro-transmissive element 13. And the projector 20 may be attached. Further, the support may be a member attached to the head, such as a headgear or a headband, instead of a helmet.

It is explanatory drawing of the presence or absence of the return | turnback of a transparent plate, a mirror, a retroreflective element, and a retrotransmissive element, (a)-(c) is a perspective view, a top view, and a side view of each member, respectively. Explanatory drawing of the return | turnback of a retroreflective element. (A) is explanatory drawing of the optical system of 1st Embodiment, (b) is explanatory drawing of the optical system of 2nd Embodiment. (A), (b), (c) is a schematic sectional drawing of the retrotransmissive element 13, respectively. (A), (b) is principal part sectional drawing of the retrotransmissive element 13, respectively. (A), (b) is principal part sectional drawing of the retrotransmissive element 13 in other embodiment, respectively. The schematic perspective view of the retrotransmissive element 13 of 3rd Embodiment. (A), (b) is explanatory drawing of the optical path in the retrotransmissive element 13 of 3rd Embodiment similarly. (A) is a schematic perspective view of the retrotransmissive element 13 of 4th Embodiment, (b) is explanatory drawing of an optical path similarly. (A) is a schematic perspective view of the retrotransmissive element 13 of the modification of 4th Embodiment, (b) is explanatory drawing of an optical path similarly. (A), (b) is a schematic sectional drawing of other embodiment of the retrotransmissive element 13, respectively. (A) is explanatory drawing of the optical path of 3rd Embodiment, (b), (c) is explanatory drawing of the optical path of the retrotransmissive element 13 of other embodiment. The schematic sectional drawing of other embodiment. (A), (b) is the top view of embodiment which concerns on the head mounted projector 100, respectively, and explanatory drawing of an optical system. Schematic explanatory drawing of a conventional head mounted projector. Schematic explanatory drawing of a conventional head mounted projector. Schematic explanatory drawing of a conventional head mounted projector.

Explanation of symbols

13 ... Retro-transparent element, 20 ... Projector,
30 ... Transparent solid layer (transparent layer),
32 ... Retroreflective element, 40 ... Semi-reflective layer, 41 ... Element body,
42 ... a through hole (void), 50 ... a gap, 52 ... a gap group, 60 ... a gap,
62 ... Wall surface (mirror surface), 65 ... void layer (transparent layer).

Claims (14)

A video projector;
An element disposed opposite to the projector, wherein incident light is transmitted to a surface opposite to the incident surface of the element, and then emitted in a direction symmetric with respect to the retrotransmission axis. Including an element (hereinafter referred to as a retrotransparent element) having
An optical system characterized in that an image is formed by retro-transmitting incident light of an unreal image from the projector through the retro-transmissive element.   The optical system according to claim 1, wherein the retrotransmissive element is curved so as to have a curved surface. The optical system according to claim 1 or claim 2 is provided on a support body mounted on a user's head,
A head mounted projector, wherein the retrotransmissive element is arranged on the support so that a virtual image can be seen by the user's eyes by the retroreflected light. A transparent layer, and one surface of the transparent layer, or a semi-reflective layer provided inside the transparent layer,
A large number of retroreflective elements that reflect light rays toward the semi-reflective layer are discretely arranged on the other surface opposite to one surface of the transparent layer or inside the transparent layer. Retroreflective element.   The retrotransmissive element according to claim 4, wherein the semi-reflective layer is curved. The semi-reflective layer is curved in a concave shape, and the reflective surface of the semi-reflective layer is formed in a concave mirror;
6. The retrotransmission according to claim 5, wherein a light beam that has passed through the semi-reflective layer and is reflected by the retroreflective element is reflected by the reflective surface, passes through the transparent layer, and exits to the outside. Sex element. The semi-reflective layer is curved into a convex shape, and the reflective surface of the semi-reflective layer is formed on a convex mirror;
The light beam incident on the transparent layer is reflected by the reflecting surface, further reflected by the retroreflective element, passes through the semi-reflective layer, and exits to the outside. Transparent element.   A plurality of gaps are arranged in a dotted line and a circle with respect to the plate-shaped element body, a plurality of the gap groups are arranged concentrically, and the wall surface of the gap is formed in a mirror surface. Retroreflective element characterized by.   The plate-like element body is formed in a circular shape and a plurality of gaps having different diameters are formed concentrically, the wall surface of the gap is formed in a mirror surface, and at least one end in the thickness direction of the element body is closed. A retrotransparent element characterized by comprising:   The retrotransmissive element according to claim 8, wherein the void is a through hole. A large number of voids are randomly arranged in the thickness direction of the element body with respect to the plate-shaped element body,
On the inner surface of the gap, a two-surface orthogonal alignment mirror composed of a first mirror surface and a second mirror surface orthogonal to each other is formed, and an intersection line of the first mirror surface and the second mirror surface is the thickness of the element body. A retro-transparent element, characterized by being arranged in a direction.   The retrotransmissive element according to claim 11, wherein the void is a through hole.   13. The plate-like element body has a curved surface, and the intersecting line of the two-surface orthogonal alignment mirror is arranged along the normal direction of the curved surface. The retrotransmissive element as described in 1.   The plate-shaped element body is provided with the two-plane orthogonal alignment mirror and the retro-transmission axis is set according to the location. The retrotransmissible element according to claim 11, wherein the retrotransmissive element is formed.

Images