JP7740562B2 - Aerial image display device and display method - Google Patents

Description

One aspect of the present invention relates to an aerial image display device and display method used, for example, to display a real image displayed on a display as a virtual image in the air.

A conventional method has been proposed in which a virtual image of a display image is projected in mid-air by reflecting the image displayed on the display using a beam splitter such as a half mirror positioned at an angle to the display. Because this method is simple in configuration and can be easily scaled up, it is used in stage productions that display life-size people (see, for example, non-patent document 1).

A common method for placing a beam splitter at an angle to the display is to use a transparent resin film with a refractive index different from that of air as the beam splitter, and apply tension to this transparent resin film to prevent wrinkles or sagging. However, the installation method of applying tension to a transparent resin film has the problem of being large-scale.

In response to this, a method has been proposed in which a thick, free-standing transparent plate such as a glass or acrylic plate is used as the beam splitter instead of a transparent resin film, and this transparent plate is positioned at an angle to the display. This method makes it possible to display aerial images with little distortion and with simple construction.

Yoshida Shun, Xie Jun, Shishido Hidehiko, Kameda Yoshinari, Kakeya Hideki, Kitahara Itaru, "Simultaneous Projection of Aerial and Floor Images for Improving Reality," Proceedings of the 23rd Annual Conference of the Virtual Reality Society of Japan, Vol. 14D-3, September 2018.

However, if a material as thick as a transparent plate is used as a beam splitter, the incident light emitted from the display will be reflected on both the front and back surfaces of the beam splitter, resulting in the display of two identical virtual images. In other words, a double image will be displayed, which will degrade the display quality of the aerial image.

This invention was made with the above-mentioned circumstances in mind, and aims to provide technology that suppresses the occurrence of double images and enables the display of high-quality aerial images.

In order to solve the above problem, one aspect of the aerial image display device of this invention comprises a display device that displays an optical image; a first optical element positioned opposite the display screen of the display device at a predetermined inclination angle and that transmits a portion of the optical image and reflects a portion of it; a second optical element positioned in close contact with a second surface of the first optical element that is the back side of the first surface facing the display screen and that transmits a first polarized component and reflects a second polarized component of the polarized components of the optical image that has passed through the first optical element; and a third optical element positioned between the first surface of the first optical element and a first viewer and that transmits only the first polarized component of the polarized components of the optical images reflected by the first optical element and the second optical element, respectively.

According to one aspect of the present invention, an optical image displayed on a display device is partially reflected toward the viewer by a first optical element, such as a half mirror, and then only the first polarization component is transmitted by a third optical element, where it is viewed by the viewer. In contrast, of the optical image that passes through the first optical element, only the second polarization component is reflected by a second optical element having reflective polarization properties, which is disposed in close contact with the rear surface of the first optical element. Therefore, the reflected optical image consisting only of the second polarization component does not pass through the third optical element and is not viewed by the viewer.

In other words, even if an optical image is reflected by the front and back surfaces of the first optical element, the optical image reflected by the back surface contains only the second polarization component, and therefore does not pass through the third optical element and is not visible to the viewer. Therefore, even if a thick first optical element is used, the occurrence of double images is suppressed, making it possible to display a high-quality aerial image.

In other words, one aspect of this invention provides technology that suppresses the occurrence of double images and enables the display of high-quality aerial images.

FIG. 1 is a diagram showing an example of the configuration of an aerial image display device according to a first embodiment of the present invention. FIG. 2 is an enlarged view of the beam splitter of the aerial image display device shown in FIG. FIG. 3 is a diagram showing a modification of the beam splitter shown in FIG. FIG. 4 is a diagram showing an example of the configuration of an aerial image display device according to the second embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of an aerial image display device according to the third embodiment of the present invention. FIG. 6 is a diagram used to explain the effects of the aerial image display device according to the first embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

[First embodiment]
(Configuration example)
1 is a diagram showing an example of the configuration of an aerial image display device according to a first embodiment of the present invention, where D1 indicates a display of the display device. The display D1 uses, for example, a liquid crystal panel, an organic EL panel, or an LED panel, and displays display information that is the source of the aerial image. The display information may be video information representing people, animals, plants, or objects, or context information representing news, subtitles, etc.

Beam splitter 2, serving as the first optical element, is positioned opposite the display surface of display D1, tilted at a predetermined angle, for example, 45 degrees or an angle close to that, relative to the display direction. Beam splitter 2 is made of a transparent plate, for example, made of acrylic or glass, and has the optical property of transmitting part of the incident light and reflecting part of it.

A reflective polarizing film 3 serving as a second optical member is closely attached to the second surface of the beam splitter 2, which is the rear surface of the first surface facing the display D1, with no air gap between them. The reflective polarizing film 3 is, for example, a wire grid polarizer, and has the optical property of transmitting, for example, the P-polarized component and reflecting the S-polarized component of the polarization components of the incident light. The reflective polarizing film 3 may also transmit the S-polarized component and reflect the P-polarized component.

Furthermore, a polarizing plate 4 is disposed between the beam splitter 2 and the viewing position of viewer US1 as a third optical component. The polarizing plate 4 has the optical property of reflecting or absorbing the S-polarized component of the incident light reflected by the reflective polarizing film 3, and transmitting the P-polarized component toward viewer US1. Note that if the reflective polarizing film 3 has the optical property of transmitting the S-polarized component and reflecting the P-polarized component, a polarizing plate 4 that reflects or absorbs the P-polarized component and transmits the S-polarized component is used.

(Example of operation)
Next, an example of the operation of the aerial image display device configured as above will be described.
FIG. 2 is a diagram illustrating the operation of the beam splitter 2 and the reflective polarizing film 3.

When display information RI is displayed on display D1, a portion of the optical image L(S+P) corresponding to this display information RI, L1(S+P), is reflected by the first surface of beam splitter 2 and enters polarizing plate 4.

Meanwhile, another portion of the optical image L(S+P) passes through the beam splitter 2, and then only the S-polarized component L2(s) is reflected by the reflective polarizing film 3 placed in close contact with the second surface on the back side of the beam splitter 2, and is incident on the polarizing plate 4.

The optical properties of the polarizing plate 4 are set to transmit the P-polarized component and reflect or absorb the S-polarized component. Therefore, the P-polarized component L3(P) of the optical image L1(S+P) reflected by the first surface (front surface) of the beam splitter 2 passes through the polarizing plate 4 and is presented to the viewer US1. In contrast, the S-polarized component L2(S) reflected by the reflective polarizing film 3 on the second surface (rear surface) of the beam splitter 2 is reflected or absorbed by the polarizing plate 4 and is not emitted to the viewer US1. Therefore, the viewer US1 can view an aerial image MI consisting only of the P-polarized component L3(P) of the optical image L1(S+P), i.e., an aerial image with reduced double images.

(Actions and Effects)
As described above, according to the first embodiment, the optical image L(S+P) displayed on the display D1 is reflected by the first surface on the front side of the beam splitter 2 and the second surface on the back side thereof, but at the second surface, the S-polarized component L2(S) is reflected by the reflective polarizing film 3 and does not pass through the polarizing plate 4, and therefore only the P-polarized component L3(P) contained in the optical image L1(S+P) reflected by the first surface on the front side of the beam splitter 2 is presented to the viewer US1.

Therefore, the viewer US1 will see an aerial image MI consisting only of the P-polarized component L3(P) of the optical image L1(S+P), with double images suppressed, thereby enabling the viewer US1 to see a high-quality aerial image.

For example, as shown in Figure 6, when beam splitter 2 is used alone, optical image L emitted from the display is reflected by the first surface on the front side and the second surface on the back side of beam splitter 2 as L1 and L2, respectively, and is presented to the viewer as is. As a result, the reflected images L1 and L2 are perceived by the viewer as a double image, which inevitably reduces the quality of the aerial image.

(Modification)
(1) FIG. 3 shows a modified example of the aerial image display device according to the first embodiment.
3, a specular reflective surface 5 is formed by, for example, metal vapor deposition on the first surface, which is the front side of the beam splitter 2. In this way, the reflectance of the optical image L1(S+P) by the first surface of the beam splitter 2 can be increased, thereby increasing the luminance of the optical image L3(P) seen by the viewer US1 and further improving the display quality of the aerial image MI.

(2) A retardation film or polarizing plate may be placed on the display surface of display D1, so that the optical image L(S+P) emitted from display D1 becomes an optical image L(P) containing only the P-polarized component. In this configuration, the optical image L(P) containing the P-polarized component is transmitted without being reflected by the reflective polarizing film 3 placed on the back side of the beam splitter 2. This prevents double images from occurring in the aerial image MI.

(3) The reflective polarizing film 3 may be configured to be placed in close contact with the first surface of the beam splitter 2 on the front side facing the viewer US1. In this case, the optical image L(S+P) emitted from the display D1 is split into an S-polarized component L(S) reflected by the front surface of the reflective polarizing film 3 and a P-polarized component L(P) that passes through the reflective polarizing film 3 and is then reflected by the beam splitter 2. Of these reflected lights, only the P-polarized component L(P) passes through the polarizing plate 4 and is visible to the viewer US1. Therefore, this configuration also makes it possible to display a high-quality aerial image MI with reduced double images.

Second Embodiment
In the second embodiment of the present invention, a first optical image displayed by a first display and a second optical image displayed by a second display are reflected in opposite directions by a pair of beam splitter 2 and reflective polarizing film 3 described in the first embodiment, and these reflected optical images are transmitted through different polarizing plates, thereby enabling a viewer to view aerial images of the first and second optical images from two different directions.

(Configuration example)
4 is a diagram showing a second embodiment of the aerial image display device according to the present invention, in which the same parts as those in FIG. 1 are given the same reference numerals and detailed explanations thereof will be omitted.

As shown in Figure 4, a second display D2 is positioned on the opposite side of the beam splitter 2 and the reflective polarizing film 3 from the first display D1, facing the reflective polarizing film 3 at an angle of approximately 45 degrees. Similar to the first display D1, the second display D2 is composed of, for example, a liquid crystal panel, an organic EL panel, or an LED panel, and displays second display information.

A second polarizing plate 6 serving as a fourth optical element is disposed between the reflective polarizing film 3 and the viewing position of the second viewer US2, perpendicular to the viewing direction of the second viewer US2. The second polarizing plate 6 has the optical property of transmitting the S-polarized component of the incident light and reflecting or absorbing the P-polarized component.

(Example of operation)
With this configuration, as described in the first embodiment, a portion of the first optical image L11(S+P) displayed on the first display D1 is reflected by the first surface on the front side of the beam splitter 2, and then only the P-polarized component L13(P) is transmitted by the first polarizing plate 4 and presented to the first viewer US1.

In contrast, a portion of the first optical image L11(S+P) passes through the beam splitter 2, and then only the S-polarized component L12(S) is reflected by the reflective polarizing film 3 arranged on the second surface on the back side.This S-polarized component L12(S) is reflected or absorbed by the first polarizing plate 4 and is not presented to the first viewer US1.

Therefore, as in the first embodiment, it is possible to present to the first viewer US1 an aerial image corresponding to the first optical image L11(S+P) displayed on the display D1 with double images suppressed.

Meanwhile, the second optical image L21(S+P) displayed by the second display D2 is split into an S-polarized component L22(S) that is reflected by the front surface of the reflective polarizing film 3, and a P-polarized component L23(P) that passes through the reflective polarizing film 3 and is then reflected by the beam splitter 2. Of these, the S-polarized component L22(S) passes directly through the second polarizing plate 6 and is presented to the second viewer US2.

In contrast, the P-polarized component L23(P) is reflected or absorbed by the second polarizing plate 6 and is not presented to the second viewer US2. Therefore, it is possible to present to viewer US2 an aerial image corresponding to the second optical image L21(S+P) with double images suppressed.

(Actions and Effects)
As described above, in the second embodiment, by sharing one set of beam splitter 2 and reflective polarizing film 3, it is possible to display two different aerial images in two opposing directions while suppressing double images in both cases.

[Third embodiment]
The third embodiment of the present invention enables the multilayer display of two different aerial images by adding a retroreflector and a retardation plate while sharing a set of beam splitter 2 and reflective polarizing film 3.

(Configuration example)
5 is a diagram showing the configuration of an aerial image display device according to a third embodiment of the present invention. In this figure, the same parts as those in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

As shown in Figure 5, a second display D2 is positioned on the opposite side of the beam splitter 2 and the reflective polarizing film 3 from the first display D1, facing the reflective polarizing film 3 at an angle of approximately 45 degrees. Similar to the first display D1, the second display D2 is composed of, for example, a liquid crystal panel, an organic EL panel, or an LED panel, and displays second display information.

A retardation plate 7 is disposed on the opposite side of the beam splitter 2 and reflective polarizing film 3 from the polarizing plate 4, i.e., on the opposite side from the viewing position of viewer US1, perpendicular to the viewing direction of viewer US1. A retroreflector 8 is disposed on the back side of this retardation plate 7. The retardation plate 7 converts incident light into circularly polarized light as it passes through. The retroreflector 8 reverses the direction of rotation of the circularly polarized light as it retroreflects the circularly polarized light that has passed through the retardation plate 7.

(Example of operation)
With this configuration, the second optical image L21(S+P) displayed on the second display D2 has its S-polarized component L22(S) reflected by the reflective polarizing film 3 toward the retarder 7 and the retroreflector 8. The S-polarized component L22(S) is then converted into circularly polarized light as it passes through the retarder 7, is retroreflected by the retroreflector 8, and passes through the retarder 7 again, whereby its polarization direction is rotated by 90 degrees and it is converted into a P-polarized component L23(P). The P-polarized component L23(P) then passes through the reflective polarizing film 3 and the beam splitter 2, and further passes through the polarizing plate 4 to be presented to the viewer US1 as an aerial image.

On the other hand, as in the first embodiment, a portion of the optical image L11(S+P) displayed on the first display D1 is reflected by the first surface on the front side of the beam splitter 2, and then only the P-polarized component L13(P) is transmitted by the polarizing plate 4 and presented to the viewer US1.

Note that another portion of the first optical image L11(S+P) passes through the beam splitter 2 and is reflected by the second surface on the rear side. However, because the reflective polarizing film 3 is closely attached to this second surface, only the S-polarized component L12(S) is reflected. This S-polarized component L12(S) is reflected or absorbed by the polarizing plate 4 and is not presented to the viewer US1. Therefore, it is possible to present to the first viewer US1 an aerial image corresponding to the first optical image L11(S+P) displayed on the display D1 with double images suppressed.

(Actions and Effects)
Therefore, according to the third embodiment, it is possible to display an aerial image (virtual image) based on the first optical image L11(S+P) displayed on the first display D1 against the background of an aerial image corresponding to the second optical image L21(S+P) displayed on the second display D2. That is, a multilayered display of two aerial images is possible. This multilayered display makes it possible to display, for example, an image of a person or an object and its shadow, thereby realizing a realistic aerial image display.

[Other embodiments]
The materials, sizes, arrangements, and types of display information displayed as an aerial image of the beam splitter, reflective polarizing film, polarizing plate, retardation plate, and retroreflector can be modified and implemented in various ways without departing from the spirit of this invention.

Although the embodiments of the present invention have been described in detail above, the above description is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, when implementing the present invention, specific configurations corresponding to the embodiments may be adopted as appropriate.

In short, this invention is not limited to the above-described embodiments, and can be embodied by modifying the components in the implementation stage without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be deleted from all of the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

D1, D2...display 2...beam splitter 3...reflective polarizing film 4, 6...polarizing plate 5...specular reflective surface 7...phase difference plate 8...retroreflector

Claims (6)

a first display device that displays a first optical image;
a first optical member disposed opposite to a display screen of the first display device at a first tilt angle, the first optical member transmitting a part of the first optical image and reflecting a part of the first optical image;
a second optical member that is disposed in close contact with a second surface of the first optical member that is a rear surface of the first surface facing the display screen, and that transmits a first polarized component and reflects a second polarized component of the polarized components of the first optical image that has passed through the first optical member;
a third optical member that is disposed between the first surface of the first optical member and a first viewer, and that transmits only the first polarization component of the optical images reflected by the first optical member and the second optical member, and presents the first polarization component to the first viewer. a second display device disposed opposite the second optical member at a second tilt angle and configured to display a second optical image toward the second optical member;
2. The aerial image display device according to claim 1, further comprising: a fourth optical element disposed between the second optical element and a second viewer, the fourth optical element transmitting only a second polarized component reflected by the second optical element among the polarized components of the second optical image. a second display device disposed opposite the second optical member at a second tilt angle and configured to display a second optical image toward the second optical member;
a retroreflective member disposed at a position facing the second optical member, with a reflective surface perpendicular or nearly perpendicular to the viewing direction of the first viewer;
a phase difference member disposed between the retroreflective member and the second optical member and giving a phase difference to incident light,
The aerial image display device according to claim 1, wherein the phase difference member and the retroreflective member convert the second polarized component of the second optical image that is reflected by the second optical member into the first polarized component and retroreflect it toward the second optical member. An aerial image display device as described in any one of claims 1 to 3, wherein the first optical member has a specular reflecting surface formed on the first surface. a first display device that displays a first optical image;
a first optical member disposed opposite to a display screen of the first display device at a first tilt angle, and having a reflective polarization characteristic of reflecting a first polarization component of the polarization components of the first optical image toward a viewer and transmitting a second polarization component of the polarization components;
a second optical member that is disposed in close contact with a second surface of the first optical member that is a rear surface of the first surface facing the display screen, and that reflects the second polarized light component that has passed through the first optical member toward the viewer;
a third optical element disposed between the first surface of the first optical element and the viewer, the third optical element transmitting only the first polarized component of the optical images reflected by the first optical element and the second optical element, and presenting the first polarized component to the viewer. a first optical member disposed opposite to a display screen of the first display device at a predetermined inclination angle, and reflecting a part of the optical image displayed on the first display device toward a viewer;
Among the polarization components of the optical image that has passed through the first optical member, only a second polarization component other than the first polarization component is reflected by a second optical member that is disposed in close contact with a second surface of the first optical member that is a rear surface of the first optical member that faces the display screen;
an aerial image display method, wherein only the first polarization component of the polarization components of the optical image reflected by the first optical element and the second optical element is transmitted toward the first viewer by a third optical element disposed between the first surface of the first optical element and the first viewer.