Aerial image display device and aerial image display method

Abstract

This aerial image display device comprises a display, a retroreflective material, a retardation plate, a beam splitter, and a polarizing plate. The display, the retroreflective material, and the beam splitter are erected on an installation bottom surface. The display emits polarized light of a display image serving as a source of an aerial image according to the polarization direction of incident light. The retroreflective material reflects incident light in an incident direction. The beam splitter reflects the polarized light of the display image emitted from the display toward the retroreflective material according to the polarization direction of the incident light, and transmits the polarized light of the display image reflected by the retroreflective material. The polarizing plate is disposed above the installation bottom surface, extends across an image formation surface of the aerial image, and transmits the polarized light transmitted through the beam splitter.

Description

[Technical Field]

[0001] The present invention relates to an aerial image display device and an aerial image display method. [Background technology]

[0002] Aerial images are real images displayed in real space, and viewers can view them without wearing a device. For this reason, aerial images are used in a variety of applications, including Augmented Reality (AR).

[0003] As a method for displaying an aerial image, for example, a method called AIRR (Aerial Imaging by Retro-Reflection) that uses a retroreflector and a beam splitter has been proposed. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Nakajima et al., Evaluation methods of retro-reflector for polarized aerial imaging by retro-reflection, 11th CLEO-PR, pp.1-2, 2015. Summary of the Invention [Problem to be solved by the invention]

[0005] Within the viewing space of a mid-air image created by AIRR, if there is an object such as a floor or table surface within the field of view of the viewer viewing the mid-air image and between the viewer and the mid-air image, the light from the mid-air image will be blocked by the object, resulting in a partially occluded mid-air image seen by the viewer.

[0006] A primary object of the present invention is to provide an aerial image display device that eliminates the obstruction of an aerial image by objects that are primarily horizontal, such as the floor or table surface, within the viewing space. [Means for solving the problem]

[0007] One aspect of the present invention is an aerial image display device. The aerial image display device includes a display, a retroreflector, a retardation plate, a beam splitter, and a polarizing plate. The display, the retroreflector, and the beam splitter are installed upright on an installation bottom surface. The display emits polarized light of a display image that is the source of the aerial image. The retroreflector reflects incident light in the direction of incidence. The beam splitter reflects the polarized light of the display image emitted from the display toward the retroreflector according to the polarization direction of the incident light, and transmits the polarized light of the display image reflected by the retroreflector. The retardation plate is disposed on the reflective surface side of the retroreflector and converts the polarized light of the display image reflected by the beam splitter into the polarized light of the display image that transmits through the beam splitter. The polarizing plate is disposed above the installation bottom surface and extends across the imaging plane of the aerial image, transmitting the polarized light that transmits through the beam splitter.

[0008] Another aspect of the present invention is an aerial image display method, which includes: providing a display that emits polarized light of a display image that is the source of the aerial image on an installation bottom surface; providing a retroreflector that reflects incident light in the incident direction on the installation bottom surface; providing a beam splitter that reflects the polarized light of the display image displayed on the display toward the retroreflector according to the polarization direction of the incident light and transmits the polarized light of the display image reflected by the retroreflector on the installation bottom surface; providing a retardation plate that converts the polarized light of the display image reflected by the beam splitter into the polarized light of the display image that transmits the beam splitter on the light incident side of the retroreflector; and providing a polarizing plate that transmits the polarized light that transmits the beam splitter above the installation bottom surface and across the imaging plane of the aerial image. [Effects of the Invention]

[0009] According to the present invention, an aerial image display device is provided that eliminates the obstruction of an aerial image by objects that are primarily horizontal, such as the floor or table surface, within a viewing space. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the basic configuration of an aerial image display device using AIRR. [Figure 2] FIG. 2 is a diagram illustrating the optical properties of a retroreflective material. [Figure 3] FIG. 3 is a diagram showing an example of a large display that is set up vertically on the floor. [Figure 4] FIG. 4 shows how the lower part of the aerial image cannot be recognized by the viewer. [Figure 5] FIG. 5 is a plan view of the AINR-based aerial image display device according to the first embodiment, viewed from above. [Figure 6] FIG. 6 is a perspective view of the aerial image display device of FIG. 5 as seen obliquely. [Figure 7] FIG. 7 is a diagram showing the imaging optical path of an aerial image in the aerial image display device of FIG. 5, developed on a plane. [Figure 8] FIG. 8 is a plan view of the aerial image display device using AINR according to the second embodiment, viewed from the side. DETAILED DESCRIPTION OF THE INVENTION

[0011] Before describing the embodiments of the present invention, the basic configuration of an aerial image display device using AINR will be described. Hereinafter, for convenience, the aerial image display device using AINR will be simply referred to as an aerial image display device.

[0012] First, the basic configuration of an aerial image display device will be described. Figure 1 shows the basic configuration of an aerial image display device 10. The aerial image display device 10 has a display 20, a beam splitter 30, and a retroreflector 40.

[0013] Display 20 is a device that displays a display image that is the basis of the aerial image based on an input video signal. Display 20 also emits light for the display image.

[0014] The retroreflective material 40 reflects incident light in the direction of incidence. The optical characteristics of the retroreflective material 40 will now be described with reference to FIG. 2. As shown in FIG. 2, assume that incident light Li is incident on a reflecting surface Pr at an incident angle θ. The incident angle is the angle between the incident light Li and a normal N to the reflecting surface Pr. The incident light Li that is incident on the reflecting surface Pr is reflected by the reflecting surface Pr and becomes reflected light. If the reflecting surface Pr is a mirror surface, the reflected light Lr reflected by the reflecting surface Pr travels in the opposite direction to the incident light Li at a reflection angle θ equal to the incident angle θ. The reflection angle is the angle between the normal N to the reflecting surface Pr and the reflected light. In contrast, if the reflecting surface Pr is the surface of the retroreflective material 40, the reflected light Lrr reflected by the reflecting surface Pr travels in the same direction as the incident light Li at a reflection angle θ equal to the incident angle θ.

[0015] 1, the beam splitter 30 will be described. The beam splitter 30 reflects the light of the image displayed on the display 20 toward the retroreflector 40, and transmits the light of the image reflected by the retroreflector 40.

[0016] Divergent light emitted from pixel Pd of display 20 is reflected by beam splitter 30 toward retroreflector 40 and enters retroreflector 40. As described above, retroreflector 40 reflects incident light in the same direction as the light it received. Therefore, the divergent light incident on retroreflector 40 is reflected by retroreflector 40 and becomes convergent light. The convergent light reflected by retroreflector 40 passes through beam splitter 30 and converges at point Pa in space. As a result, the light of the display image displayed on display 20 converges onto a plane including point Pa to become aerial image Ia. The aerial image Ia is displayed at a position symmetrical to the display 20 with respect to beam splitter 30. To viewer V, the aerial image Ia appears to be floating in the air.

[0017] By vertically setting up the display 20, beam splitter 30, and retroreflector 40 that make up the aerial image display device 10 on a horizontal floor surface, it is possible to display an aerial image that stands upright on the floor surface.

[0018] 3 is a diagram showing an example of a large display 20 set up vertically on a horizontal floor surface F. The display 20 is, for example, a large LED display, although it is not limited to this. Here, the display 20 is assumed to be a vertically long large display large enough to display a life-size display image Id of a person.

[0019] The field of view of the aerial image Ia is the range connecting the viewpoint of the viewer viewing the aerial image Ia and the reflective surface of the retroreflective material 40. Therefore, the field of view of the aerial image Ia is limited. The light that represents the lower part of the aerial image Ia is blocked by the bottom surface of the optical system in the optical path, so the lower part of the aerial image Ia cannot be recognized by the viewer. Figure 4 shows how the lower part of the aerial image Ia cannot be recognized by the viewer.

[0020] First Embodiment The overall configuration of an aerial image display device 10 according to the first embodiment will be described with reference to Figs. 5 to 7. Fig. 5 is a plan view of the aerial image display device 10 according to the first embodiment, viewed from above. Fig. 6 is a perspective view of the aerial image display device 10 of Fig. 5, viewed from an oblique angle. Fig. 7 is a plan view showing the imaging optical path of an aerial image in the aerial image display device of Fig. 5.

[0021] The aerial image display device 10 according to this embodiment has a retardation plate 42 and a polarizing plate 50 in addition to the display 20, beam splitter 30, and retroreflector 40 described in the basic configuration. The display 20, beam splitter 30, retroreflector 40, and retardation plate 42 are all installed vertically on a flat installation bottom surface BP. The basic configuration of the display 20, beam splitter 30, and retroreflector 40 is as described above.

[0022] The retardation plate 42 is disposed on the reflective surface side of the retroreflector 40. The retardation plate 42 may be attached to the retroreflector 40, or may be disposed with a gap therebetween.

[0023] 6 and 7, the polarizing plate 50 is disposed above the installation bottom surface BP and extends across the imaging plane IP of the aerial image Ia. The polarizing plate 50 extends parallel to the installation bottom surface from the beam splitter 30. The polarizing plate 50 transmits light that passes through the beam splitter 30.

[0024] In the aerial image display device 10 of this embodiment, as shown in Figure 5, the display 20 and the retroreflective material 40 are arranged so that, when viewed from above, they are perpendicular to each other and the beam splitter 30 forms a 45-degree angle with respect to both the display 20 and the retroreflective material 40; however, the relative positions of the display 20, the beam splitter 30, and the retroreflective material 40 are not limited to this.

[0025] In this embodiment, the display 20 emits polarized light as the light of the display image Id. Here, the light of the display image Id is light that displays the aerial image Ia. That is, in this specification, the term "light of the display image" and the term "light that displays the aerial image" are sometimes used, but the two terms are synonymous. Polarized light is also classified according to the trajectory of the peak of the vibration of the electric field vector when viewed from behind the light traveling direction. Hereinafter, for convenience, the trajectory of the peak of the vibration of the electric field vector will be referred to as the polarization direction.

[0026] The beam splitter 30 is an optical element that reflects or transmits incident light depending on the polarization direction of the incident light. For example, the beam splitter 30 can be configured with a reflective polarizing plate, a wire grid, or the like.

[0027] The phase difference plate 42 converts the light reflected by the beam splitter 30 into light that is transmitted through the beam splitter 30. The phase difference plate 42 is a quarter-wave plate.

[0028] For example, the display 20 emits linearly polarized light whose polarization direction is perpendicular to the installation bottom surface BP. Hereinafter, for convenience, linearly polarized light whose polarization direction is perpendicular to the installation bottom surface BP will be referred to as vertical linearly polarized light, and linearly polarized light whose polarization direction is horizontal to the installation bottom surface BP will be referred to as horizontal linearly polarized light.

[0029] The beam splitter 30 reflects the vertically linearly polarized light and transmits the horizontally linearly polarized light. The retarder 42 converts the vertically linearly polarized light into horizontally linearly polarized light. The polarizer 50 transmits the horizontally linearly polarized light. The polarizer 50 forms the floor of the viewing space VA for the viewer of the aerial image.

[0030] Next, with reference to FIG. 7, the imaging optical path of the aerial image Ia will be described. The display 20 displays a display image Id, which is the source of the aerial image Ia. The display 20 also emits vertically linearly polarized light, which is the light of the display image Id. The vertically linearly polarized light emitted from the display 20 is reflected by the beam splitter 30 and travels toward the retroreflector 40. The vertically linearly polarized light passes through the retardation plate 42, becomes circularly polarized light, and enters the retroreflector 40. The retroreflector 40 retroreflects the circularly polarized light, converting divergent light into convergent light. The circularly polarized light reflected by the retroreflector 40 passes through the retardation plate 42, becomes horizontally linearly polarized light, and travels toward the beam splitter 30. The beam splitter 30 transmits the incident horizontally linearly polarized light. The horizontally linearly polarized light that passes through the beam splitter 30 is imaged on an image plane IP, forming the aerial image Ia.

[0031] The viewer V in the viewing area VA sees the portion of the aerial image Ia located above the upper surface of the polarizing plate 50 directly, and the portion of the aerial image Ia located below the upper surface of the polarizing plate 50 through the polarizing plate 50. As a result, the viewer V in the viewing area VA perceives the horizontal polarizing plate 50 as a black board by absorbing half of the ambient light, while the light from the aerial image Ia passes through the polarizing plate 50, allowing the viewer V to view the aerial image Ia displayed at a position overlapping with the horizontal plane without being obstructed. In other words, the obstruction of the aerial image Ia by the horizontal plane in the viewing space VA is eliminated.

[0032] In this case, if the beam splitter 30 and the polarizing plate 50 have ideal optical characteristics, the portion of the aerial image Ia located above the upper surface of the polarizing plate 50 and the portion of the aerial image Ia located below the upper surface of the polarizing plate 50 can be made to have the same brightness.

[0033] Second Embodiment An aerial image display device 10 according to the second embodiment will be described with reference to Fig. 8. Fig. 8 is a plan view of the aerial image display device 10 according to the second embodiment as viewed from the side.

[0034] In the aerial image display device 10 of this embodiment, the polarizing plate 50 is supported by a support 60 provided on the installation bottom surface BP, and forms the top of a table placed in the viewing space VA for the viewer V of the aerial image Ia.

[0035] The aerial image display device 10 also includes a polarizing plate 32 attached to a portion of the beam splitter 30 located above the polarizing plate 50. The polarizing plate 32 is a linear polarizing plate having a transmission axis that coincides with the transmission axis of the beam splitter 30.

[0036] In this configuration, the imaging light of the portion of the aerial image Ia located below the polarizing plate 50 passes only through the beam splitter 30 to form an image, and the imaging light of the portion of the aerial image Ia located above the polarizing plate 50 passes through the beam splitter 30 and the polarizing plate 32 to form an image.

[0037] Even if the polarizing plate 50 does not have ideal optical properties, such as slightly absorbing light in the transmission axis direction, by providing the polarizing plate 32, the portion of the aerial image Ia located above the polarizing plate 50 and the portion of the aerial image Ia located below the polarizing plate 50 can have the same brightness. [Explanation of symbols]

[0038] 10...Aerial image display device 20...Display 30...Beam splitter 32...Polarizing plate 40...Retroreflective material 42...Retardation plate 50...Polarizing plate 60...Support BP…Installation bottom surface Id…display image Ia…Aerial image

Claims

1. a display that is erected on the installation bottom surface and that outputs polarized light of a display image that is the source of the aerial image; A retroreflective material that is erected on the installation bottom surface and reflects incident light in the incident direction; a beam splitter that is erected on the installation bottom surface and that reflects polarized light of the display image emitted from the display toward the retroreflector according to the polarization direction of incident light, and transmits polarized light of the display image reflected by the retroreflector; a phase difference plate disposed on the reflective surface side of the retroreflective material, which changes the polarized light of the display image reflected by the beam splitter into the polarized light of the display image transmitted through the beam splitter; a polarizing plate disposed above the installation bottom surface, extending across an imaging plane of the aerial image, and transmitting polarized light transmitted through the beam splitter; Aerial image display device.

2. The polarizer extends from the beam splitter parallel to the installation bottom surface.

2. The aerial image display device according to claim 1.

3. the polarizer constitutes the floor of a viewing space for a viewer of the aerial image; 3. The aerial image display device according to claim 2.

4. the polarizing plate constitutes a tabletop placed within a viewing space for a viewer of the aerial image; 3. The aerial image display device according to claim 2.

5. the display emits linearly polarized light whose polarization direction is perpendicular to the installation bottom surface, The retardation plate is a quarter wave plate.

2. The aerial image display device according to claim 1.

6. Further, a polarizing plate is attached to a portion of the beam splitter located above the polarizing plate.

2. The aerial image display device according to claim 1.

7. A display that emits polarized light of the display image that is the source of the aerial image is installed on the installation base. a retroreflective material that reflects incident light in the direction of incidence is provided on the installation bottom surface; a beam splitter that reflects the polarized light of the display image emitted from the display toward the retroreflective material in accordance with the polarization direction of the incident light and transmits the polarized light of the display image reflected by the retroreflective material, the beam splitter being provided upright on the installation bottom surface; a phase difference plate that converts the polarized light of the display image reflected by the beam splitter into the polarized light of the display image that transmits through the beam splitter is disposed on the light incident side of the retroreflective material; a polarizing plate that transmits light that passes through the beam splitter is disposed above the installation bottom surface and across the imaging plane of the aerial image; Aerial image display method.

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