Aerial display apparatus

An aerial display apparatus includes: a display device which displays an image; a mirror device which includes a plurality of optical elements each including two reflective surfaces that are orthogonally disposed, which reflects display light from the display device, and which forms an aerial image at a position that is plane-symmetrical to the display device; and a light shielding member which is disposed on an optical path between the display device and the aerial image, which includes an opening that allows a portion of incident light to pass through, and which shields light incident on a region other than the opening.

FIELD

The present invention relates to an aerial display apparatus.

BACKGROUND

A dihedral corner reflector array has been proposed in which real mirror-image forming optical systems (dihedral corner reflectors) that form a real image of an observation target in a space of the observer side are disposed in an array as basic components to allow observation of a real image of an observation target formed in the air (see Patent Document 1). Consideration has been given to application of a display device that uses a mirror device such as a dihedral corner reflector array to a non-contact input device (button) in the fields of medicine and food, in combination with an infrared touch panel, as well as amusement.

CITATION LIST

Patent Literature

SUMMARY

According to an aspect of the present invention, there is provided an aerial display apparatus comprising:

a display device which displays an image;

a mirror device which includes a plurality of optical elements each including two reflective surfaces that are orthogonally disposed, which reflects display light from the display device, and which forms an aerial image at a position that is plane-symmetrical to the display device; and

a light shielding member which is disposed on an optical path between the display device and the aerial image, which includes an opening that allows a portion of incident light to pass through, and which shields light incident on a region other than the opening.

According to an aspect of the present invention, there is provided an aerial display apparatus, comprising:

a display device which displays an image;

a mirror device which includes a plurality of optical elements each including two reflective surfaces that are orthogonally disposed, which reflects display light from the display device, and which forms an aerial image at a position that is plane-symmetrical to the display device; and

a light limiting device which is disposed on an optical path between the display device and the aerial image, and which allows a light component of incident light having an angle of emission that falls within a predetermined range to be transmitted therethrough.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference to the drawings. The drawings are schematic or conceptual, and the dimensions, ratios, and the like of each drawing are not necessarily the same as the actual ones. Even when the same portions are shown in the drawings, the dimensional relationship and the ratio may be different. In particular, several embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention is not specified by the shape, structure, arrangement, or the like of the components. In the following description, elements having the same function and configuration will be denoted by the same reference numerals, and redundant descriptions will be made only when necessary.

[1] First Embodiment

[1-1] Principle of Aerial Display Apparatus

An aerial display apparatus is configured, for example, to form an image of light emitted from a display surface of a liquid crystal display, using an aerial imaging device (mirror device) such as a dihedral corner reflector.

A configuration of a mirror device10used in an aerial display apparatus will be described.FIG.1is a perspective view of the mirror device10.

The mirror device10includes a planar base member11and a plurality of optical elements12provided on the base member11. The optical elements12are arranged, for example, in a matrix so as to extend in an x direction and a y direction that are orthogonal to each other. Each of the optical elements12has two reflective surfaces that are orthogonally disposed. Each optical element12has a cubic or rectangular parallelepiped shape. The base member11and the optical elements12are configured of a transparent resin.

InFIG.1, 36 (=6×6) optical elements12are shown as an example; however, in actuality, a greater number of optical elements12are disposed. The number and size of the optical elements12can be freely set according to the specification of the aerial display apparatus. A distance between two optical elements12can be freely set according to the specification of the aerial display apparatus.

FIG.2is a schematic diagram illustrating the principle of the aerial display apparatus. The aerial display apparatus includes a display device20that displays an image on a display surface and a mirror device10. InFIG.2, the base member11of the mirror device10is not illustrated, and only the optical elements12are extracted for illustration, for the ease of understanding of the drawing. The optical elements12are arranged on an x-y plane. The z direction is a height direction of the optical elements12.

Light (display light) emitted from the display device20is reflected by two side surfaces of each of the optical elements12. InFIG.2, the optical path of light reflected by the hatched optical element12is extracted for illustration. The light emitted from the display device20forms an image at a position that is plane-symmetrical to the display device20with respect to the mirror device10, and an aerial image30is formed at that position. An observer can visually recognize the aerial image.

FIG.3is a schematic diagram illustrating a state of light that is reflected twice by a single optical element12.FIG.4is a diagram illustrating an optical path when the optical element12is viewed from the z direction.FIG.5is a diagram illustrating an optical path when the optical element12is viewed from the y direction.FIG.6is a diagram illustrating an optical path when the optical element12is viewed from the x direction.

Light incident from a bottom surface of the optical element12is reflected by a first side surface, further reflected by a second side surface that is perpendicular to the first side surface, and then emitted from a top surface.

It should be noted that for light incident on a given side surface of the optical element12, not all the components of the light are reflected by that side surface, and the light is divided into a reflective component and a transmissive component. The reflective component is a component of light reflected by the side surface at an angle of reflection corresponding to the incident angle, and the transmissive component is a component of light that is linearly transmitted through the side surface.

Next, a ghost that is formed at an unintended position will be described. A ghost is a double image that appears in the vicinity of the aerial image30.FIG.7is a schematic diagram illustrating a ghost31displayed by the aerial display apparatus.

The ghost31is an image formed by light that is reflected only once (i.e., light that is not reflected twice) by the mirror device10. The ghost31is formed at a position that is not plane-symmetrical to the display device20with respect to the mirror device10.

FIG.8is a schematic diagram illustrating a state of light reflected once by a single optical element12.FIG.9is a diagram illustrating an optical path when the optical element12is viewed from the z direction.FIG.10is a diagram illustrating an optical path when the optical element12is viewed from the y direction.FIG.11is a diagram illustrating an optical path when the optical element12is viewed from the x direction.

Light incident from a bottom surface of the optical element12is reflected by a first side surface, and is then transmitted through a second side surface that is perpendicular to the first side surface. The light that travels along this path forms an image at a position that is not plane-symmetrical to the display device20with respect to the mirror device10, thereby displaying a ghost31.

Next, unwanted light will be described. Unwanted light is a light component that does not contribute to formation of a real image.FIG.12is a schematic diagram illustrating unwanted light32of the aerial display apparatus.

The unwanted light32is light that is not reflected at all by the mirror device10. The unwanted light32is linearly transmitted through the mirror device10.

FIG.13is a schematic diagram illustrating a state of light that is not reflected at all by a single optical element12.FIG.14is a diagram illustrating an optical path when the optical element12is viewed from the z direction.FIG.15is a diagram illustrating an optical path when the optical element12is viewed from the y direction.FIG.16is a diagram illustrating an optical path when the optical element12is viewed from the x direction.

The light incident from the bottom surface of the optical element12is not reflected by the first side surface, and is linearly transmitted through the first side surface.

The unwanted light32brightens the periphery of the aerial image30. Due to the unwanted light32, the contrast of the aerial image30is reduced.

[1-2] Configuration of Aerial Display Apparatus1

Next, a configuration of an aerial display apparatus1according to a first embodiment will be described.FIG.17is a perspective view of the aerial display apparatus1according to the first embodiment.

The aerial display apparatus1includes a mirror device10, a display device20, and a light shielding film (light shielding member)40. InFIG.17, a plurality of devices constituting the aerial display apparatus1are shown as if they are floating; however, these devices are fixed at the illustrated positions by unillustrated support members. The same applies to the subsequent drawings.

The display device20includes a display surface, and displays an image on the display surface. The display surface of the display device20is disposed on the side of the mirror device10. Various displays can be used as the display device20; example configurations of the display device20include a liquid crystal display device, an organic electroluminescence (EL) display device, etc.

The mirror device10is disposed at a distance from the display device20. Upon receiving display light from the display device20, the mirror device10reflects the display light toward an opposite side of the display device20. Thereby, the mirror device10forms the aerial image30at a position that is plane-symmetrical to the display device20. The size (area) of the mirror device10is set to be larger than an area capable of receiving display light for forming the aerial image30, namely, with a margin from the area capable of receiving the display light.

The mirror device10may be disposed in such a manner that the optical elements12face the display device20, or the base member11faces the display device20.FIG.17is a configuration example in which the optical elements12are disposed on the side of the display device20, namely, a configuration example in which the mirror device10ofFIG.1is disposed upside down.

The light shielding film40is provided so as to be in contact with the mirror device10. The light shielding film40is, for example, adhered to the mirror device10. The light shielding film40may be provided on the side of the base member11of the mirror device10, or on the side of the optical elements12.

The light shielding film40includes, at its center, an opening40A. The opening40A allows light that forms the aerial image30to pass through. The light shielding film40has a function of shielding the ghost and/or unwanted light. The light shielding film40is configured of, for example, a resin mixed with a black dye. Examples of the resin used for the light shielding film40include polyethylene terephthalate (PET).

The opening40A is, for example, a circle. The opening40A is set to have an area that allows display light for forming the aerial image30to be transmitted therethrough, and allows ghosts and/or unwanted light to be shielded. The area of the opening40A is appropriately set in accordance with the size (area) of the display screen of the display device20, the distance between the display device20and the mirror device10, and the positional relationship between the display device20and the mirror device10. The area of the opening40A is, for example, larger than the area of the display device20.

[1-3] Advantageous Effects of First Embodiment

As described in detail above, in the first embodiment, an aerial display apparatus1includes a display device20that displays an image, a mirror device10that reflects display light from the display device20, and a light shielding film (light shielding member)40provided on the mirror device10on an opposite side of the display device20. The mirror device10includes a plurality of optical elements12each including two reflective surfaces that are orthogonally disposed, and forms an aerial image30at a position that is plane-symmetrical to the display device20. The light shielding film40includes an opening40A that allows a portion of incident light to pass through, and shields light incident on a region other than the opening40A.

According to the first embodiment, since the aerial display apparatus1is capable of shielding light that forms a ghost, it is possible to prevent the ghost from being visually recognized by the observer. Further, since the aerial display apparatus1is capable of shielding unwanted light, the contrast of the aerial image30can be improved. As a result, it is possible to improve the display quality of the aerial display apparatus1.

[2] Second Embodiment

In a second embodiment, a light shielding member for shielding ghosts and/or unwanted light is disposed at a distance from a mirror device10.

FIG.18is a perspective view of an aerial display apparatus1according to the second embodiment. The aerial display apparatus1includes a mirror device10, a display device20, and a light shielding plate (light shielding member)40.

The light shielding plate40is disposed at a distance from the mirror device10on an opposite side of the display device20with respect to the mirror device10. The light shielding plate40is configured of, for example, a resin mixed with a black dye. The light shielding plate40has a function of shielding the ghost and/or unwanted light.

According to the second embodiment, the light shielding plate40is capable of shielding a larger number of light components other than the light for forming the aerial image30. It is thereby possible to shield ghosts and/or unwanted light.

In a third embodiment, ghosts and/or unwanted light are shielded by using a light limiting device that allows only light which has an angle of emission that falls within a predetermined range to be transmitted therethrough.

FIG.19is a perspective view of an aerial display apparatus1according to the third embodiment. The aerial display apparatus1includes a mirror device10, a display device20, and a light limiting device41.

The light limiting device41is disposed on an opposite side of the display device20with respect to the mirror device10. The light limiting device41may be disposed in contact with the mirror device10, or at a distance from the mirror device10.

The light limiting device41has a function of allowing a light component of light incident thereon which has an angle of emission that falls within a predetermined range to be transmitted therethrough, and of shielding a light component of the incident light which has an angle of emission that falls outside the predetermined range. That is, the light limiting device41has a function of allowing display light for forming an aerial image30to be transmitted therethrough, and of shielding ghosts and/or unwanted light.

FIG.20is a perspective view of the light limiting device41. The light limiting device41includes a base member42, a plurality of transmissive layers43, and a plurality of light shielding layers44. The transmissive layers43and the light shielding layers44are disposed in an alternating manner, and adjacent layers are in contact with each other. The transmissive layers43and the light shielding layers44are disposed side by side in the x direction, each extending in the y direction. The base member42and the transmissive layers43allow light to be transmitted therethrough. The base member42and the transmissive layers43are configured of a transparent resin. The light shielding layers44shield light. The light shielding layers44are configured of, for example, a resin mixed with a black dye. The angle of emission of the light limiting device41is set within a range equal to or greater than 0 degrees and equal to or smaller than 60 degrees on each of the right and left sides, with respect to the normal. More desirably, the angle of emission of the light limiting device41is set within a range equal to or greater than 0 degrees and equal to or smaller than 45 degrees on each of the right and left sides, with respect to the normal. The angle of emission is an angle from the normal of the light limiting device41.

According to the third embodiment, it is possible to shield ghosts and/or unwanted light. Thereby, it is possible to improve the display quality of the aerial display apparatus1.

The light limiting device41may be disposed between the display device20and the mirror device10. It may be disposed, for example, in contact with the mirror device10on the side of the display device20. In the present embodiment, light that may become a ghost and/or unwanted light can be shielded before it enters the mirror device10. Thereby, it is possible to improve the display quality of the aerial display apparatus1.

Moreover, the light limiting device41shown in the third embodiment can be additionally applied to the configurations of the first and second embodiments.

In the fourth embodiment, a liquid crystal display device is used as a display device. In addition, the light emitted from a back light is limited to a light component which has an angle of emission that falls within a predetermined range, using a light limiting device41.

FIG.21is a perspective view of an aerial display apparatus1according to the fourth embodiment. The aerial display apparatus1includes a mirror device10, a liquid crystal display device (light modulating device)20, a light source unit (back light)21, and a light limiting device41.

The back light21produces illumination light and emits the illumination light toward the liquid crystal display device20. The back light21is configured of a surface light source.

The light limiting device41is disposed between the back light21and the liquid crystal display device20. The light limiting device41has a function of allowing a light component of light incident thereon which has an angle of emission that falls within a predetermined range to be transmitted therethrough, and of shielding a light component of the incident light which has an angle of emission that falls outside the predetermined range. That is, the light limiting device41has a function of allowing illumination light for forming an aerial image30to be transmitted therethrough, and of shielding in advance illumination light that causes ghosts and/or unwanted light. The structure of the light limiting device41ofFIG.21is the same as the light limiting device41ofFIG.20, except for the difference in size.

The liquid crystal display device20receives illumination light that is transmitted through the light limiting device41. The liquid crystal display device20allows illumination light to be transmitted therethrough, and performs light modulation. The liquid crystal display device20displays a desired image on its display surface. A driving mode of the liquid crystal display device20is not particularly limited, and a twisted nematic (TN) mode, a vertical alignment (VA) mode, a homogeneous mode, or the like can be used.

According to the fourth embodiment, it is possible to shield the illumination light that causes ghosts and/or unwanted light at a stage before the display light enters the mirror device10. Thereby, it is possible to improve the display quality of the aerial display apparatus1.

The light limiting device41may be disposed on an opposite side of the back light21with respect to the display device20. The light limiting device41having substantially the same size as the display device20may be disposed in contact with or at a distance from the display surface of the display device20.

When a self-luminous display device such as an organic EL display device is used, the light limiting device41may be disposed in contact with or at a distance from the display surface of the display device.

Moreover, the light limiting device41shown in the fourth embodiment can be additionally applied to the configurations of the first and second embodiments.

In a fifth embodiment, a region of the mirror device10in which a plurality of optical elements12are disposed is reduced to a size capable of reflecting light that contributes to formation of an aerial image. The light that causes ghosts and/or unwanted light is suppressed from being diffused by the optical element12.

FIG.22is a perspective view of an aerial display apparatus1according to the fifth embodiment. The aerial display apparatus1includes a mirror device10and a display device20.

The mirror device10includes a base member11and a plurality of optical elements12provided on the base member11. In the example ofFIG.22, the optical elements12are disposed on the base member11on an opposite side of the display device20with respect to the base member11. As a matter of course, a plurality of optical elements12may be disposed so as to face the display device20.

A region in which the optical elements12are disposed is limited to a central portion of the base member11. The region in which the optical elements12are disposed is reduced to a size capable of reflecting light that contributes to formation of an aerial image30. Thereby, it is possible to suppress the display light emitted from the display device20from being diffused in a region other than the region in which the optical elements12are disposed. As a result, it is possible to improve the display quality of the aerial display apparatus1.

The mirror device10of the fifth embodiment can be applied to the first to fourth embodiments.

In each of the embodiments, the mirror device10is configured to include a plurality of optical elements12each having a rectangular parallelepiped shape. The structure of the mirror device10is not limited thereto. The mirror device10may be configured, for example, to include a plurality of holes in a transparent base member, each hole having two reflective surfaces that are orthogonally disposed. Specifically, the mirror device10is configured in such a manner that a plurality of holes each having a square or rectangular planar shape are disposed in a matrix in a transparent base member. In other words, the optical element that reflects light twice may be either convex or concave.

The present invention is not limited to the above-described embodiments, and can be modified in practice, without departing from the gist of the invention. Furthermore, the embodiments described above include inventions at various stages, and various inventions can be configured by an appropriate combination of a plurality of components disclosed in a single embodiment or an appropriate combination of components disclosed in different embodiments. For example, if the object of the invention is achieved and advantages of the invention are attained even after some of the structural elements are deleted from all the structural elements disclosed in the embodiment, the structure made up of the resultant structural elements may be extracted as an invention.