Patent Publication Number: US-2023161174-A1

Title: Floating-image display device and floating-image display method

Description:
TECHNICAL FIELD 
     The present invention relates to a floating image display apparatus and a floating image display method. 
     BACKGROUND ART 
     A known floating image projection apparatus projects a virtual image of a subject displayed on a display apparatus as a floating image onto a space. NPL 1 discloses a technology in which a plurality of half mirrors are installed in a depth direction and floating images are projected in multiple layers. 
     CITATION LIST 
     Non Patent Literature 
     
         
         NPL 1: Motohiro MAKIGUCHI, Arinobu NIIJIMA, Hideaki TAKADA, Tatsuya MATSUI, Yasuyuki YABUMOTO, Masanori YOKOYAMA, “Proposal of Compact Multilayer Floating-Image Projection System Using Smartphone”, IPSJ Interaction 2016, Information Processing Society of Japan, 24 Feb. 2016, pp. 150-157 
       
    
     SUMMARY OF THE INVENTION 
     Technical Problem 
     A case is considered where a technology of projecting the floating image in multiple layers by installing a plurality of the half mirrors is applied to sports watching. For example, the above technology is applied to watching a badminton game, and on a badminton court, each of a player on a front side of the court and a player on a deeper side of the court is displayed in separate floating images. Accordingly, this makes it possible to realize an experience of being given feeling of watching the badminton game performed on the court. 
     However, the half mirror that projects the floating image on the deeper side needs to be installed on a stage (court), and thus, the arrangement of a real object and the performer on the stage, and a stage production such as lighting are restricted. 
     The present invention has been made in view of the above issue, and an object of the present invention is to provide a multilayer floating image display apparatus that does not interfere with the production on the stage. 
     Means for Solving the Problem 
     According to an aspect of the present invention, a floating image display apparatus includes: a first display unit configured to be installed to have a display surface facing toward a ground; a first optical element configured to be installed to be inclined with respect to the ground, and configured to transmit a part of light emitted from the first display unit and reflect a part of the light; a second display unit configured to be installed to have a display surface perpendicular to the ground; and a second optical element configured to be installed to be perpendicular to the ground, and configured to transmit a part of light emitted from the second display unit and reflect a part of the light. 
     According to another aspect of the present invention, a floating image display method includes: displaying a first image by a first display unit installed to have a display surface facing toward a ground; emitting light of the first image to a first optical element that is installed to be inclined with respect to the ground, transmits a part of incident light, and reflects a part of the incident light; displaying a second image by a second display unit installed to have a display surface perpendicular to the ground; and emitting light of the second image to a second optical element that is installed to be perpendicular to the ground, transmits a part of incident light, and reflects a part of the incident light. 
     Effects of the Invention 
     According to the present invention, the multilayer floating image display apparatus that does not interfere with the production on the stage can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a diagram illustrating a schematic configuration example of a floating image display apparatus according to a present embodiment. 
         FIG.  2    is a diagram illustrating a schematic configuration example of a floating image display apparatus according to a comparative example. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Floating Image Display Apparatus of Present Embodiment 
     Hereinafter, a floating image display apparatus of the present embodiment will be described with reference to the drawings. 
     The floating image display apparatus of the present embodiment will be described with reference to  FIG.  1   . The floating image display apparatus illustrated in the drawing is a display apparatus that projects the floating image in multiple layers on a front side and a deeper side of a stage  30  as viewed from a spectator  100 . The stage  30  is, for example, an actual court of an indoor badminton competition venue, and a length of a line of the court in a left and right direction in the drawing is 13.4 m. An actual net  31  is installed in a center of the stage  30 . The spectator  100  recognizes, as a floating image, a virtual image B 1  on the court on a front side of the net  31  and a virtual image B 2  on the court on a back side of the net  31 , which are projected by the floating image display apparatus. By projecting an image capturing the player of the badminton game performed in the other venue as a floating image on the actual court, the spectator  100  can watch the badminton game. 
     The floating image display apparatus illustrated in  FIG.  1    includes a first display unit  11 , a second display unit  12 , a first optical element  21 , and a second optical element  22 . 
     The first display unit  11  is disposed at a position with a height H from a ground (the same plane as an upper surface of the stage  30 ) between a spectator&#39;s seat and the stage  30 , such that a display surface of the first display unit  11  is parallel with the ground and faces downward (toward the first optical element  21 ). As the first display unit  11 , for example, a display apparatus such as an LED display and an organic EL display can be used. A display image A 1  is displayed on the display surface of the first display unit  11 . The display image A 1  is, for example, an image of the player on the court on the front side of the net  31 . 
     The first optical element  21  is installed to be inclined with respect to the ground at a position below the first display unit  11 , and receives light emitted from the first display unit  11 . In the example illustrated in  FIG.  1   , at a position corresponding to a lower end of the first display unit  11 , the first optical element  21  is installed such that one side of the first optical element  21  is brought into contact with the ground and inclined at 45 degrees with respect to the ground. A point at which the first optical element  21  is brought into contact with the ground is referred to as a base point P. The first optical element  21  is a rectangular or square plate-like optical element, reflects a part of the incident light and transmits a part of the incident light. For example, a half mirror can be used as the first optical element  21 . 
     The second display unit  12  is installed at a position away from the base point P (installation position of the second optical element  22 ) to the spectator&#39;s seat side by a distance W, such that the display surface of the second display unit  12  is perpendicular to the ground and faces the stage  30  side. In the example illustrated in  FIG.  1   , the second display unit  12  is installed under the spectator&#39;s seat, but the present invention is not limited to this. As the second display unit  12 , for example, a display apparatus such as an LED display and an organic EL display can be used. A display image A 2  is displayed on the display surface of the second display unit  12 . The display image A 2  is, for example, an image of the player on the court on the back side of the net  31 . 
     The second optical element  22  is installed to be erected on the ground between the second display unit  12  and the stage  30 , and receives light emitted from the second display unit  12 . In the example illustrated in  FIG.  1   , the second optical element  22  is installed at a position of the base point P such that one side of the second optical element  22  is brought into contact with the ground and the second optical element  22  is perpendicular to the ground. In other words, the second optical element  22  is installed so as to be parallel with the display surface at a position away from the second display unit  12  by the distance W. The second optical element  22  is a rectangular or square plate-like optical element, reflects a part of the incident light and transmits a part of the incident light. For example, a half mirror can be used as the second optical element  22 . 
     To prevent total reflection, installation positions of the second display unit  12  and the second optical element  22  are adjusted such that an incident angle of the light incident on the second optical element  22  from the second display unit  12  is equal to or less than the angle θ 0  in which sin θ 0 =n 1  (n 1  is a refractive index of the second optical element  22 ). 
     Next, the floating image projected by the floating image display apparatus of  FIG.  1    will be described. 
     First, the virtual image B 1  formed by the first display unit  11  and the first optical element  21  will be described. When the first display unit  11  displays the display image A 1 , the light of the display image A 1  is directed toward the first optical element  21 . The first optical element  21  reflects a part of the light of the display image A 1  and emits the light toward the spectator  100 . The virtual image B 1  is projected at a position away by the same distance D F  as the height H from the base point P to the first display unit  11 . In the example illustrated in  FIG.  1   , the height H at which the first display unit  11  is installed is adjusted such that the virtual image B 1  is projected on the court on the front side of the net  31 . Note that in the example illustrated in  FIG.  1   , the first display unit  11  is installed at the same position as the upper side of the second optical element  22 , but the height H at which the first display unit  11  is installed can be determined according to the position at which the virtual image B 1  is to be projected. 
     Next, the virtual image B 2  formed by the second display unit  12  and the second optical element  22  will be described. When the second display unit  12  displays the display image A 2 , the light of the display image A 2  is directed toward the second optical element  22 . The second optical element  22  reflects a part of the light of the display image A 2  and emits the light toward the spectator  100 . The virtual image B 2  is projected at a position away by the same distance D R  as the distance W from the base point P to the second display unit  12 . In the example illustrated in  FIG.  1   , the distance W between the second display unit  12  and the second optical element  22  is adjusted such that the virtual image B 2  is projected on the court on the back side of the net  31 . Note that in the example of  FIG.  1   , the first optical element  21  and the second optical element  22  are installed at the same base point P, but the present invention is not limited to this. The second optical element  22  may be installed at a point closer to the spectator&#39;s seat than the first optical element  21 . 
     In the example illustrated in  FIG.  1   , a net  32  having the same shape as that of the net  31  on the stage  30  is installed between the second display unit  12  and the second optical element  22 . The net  31  and the net  32  are at the same distance from the second optical element  22 . The net  32  blocks a part of the light from the second display unit  12  and the projection is performed such that a part of the virtual image B 2  is blocked by the net  31 . Accordingly, an occlusion by the net  31  can be reproduced in the floating image. 
     Next, an upper limit of a viewing zone of the floating image display apparatus in  FIG.  1    will be described. 
     The upper limit V of the viewing zone illustrated in  FIG.  1    is represented by the following equations by using the distance D R  from the second optical element  22  to the virtual image B 2 , a distance D V  from the second optical element  22  to the spectator  100 , the height H of the second optical element  22 , and the height h of the second display unit  12 . 
     
       
         
           
             
               
                 
                   
                     
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     It is possible to dispose the spectator  100  in a vertical direction as long as his/her position is lower than V+h, where V is the upper limit of the viewing zone. That is, the present floating image display apparatus can be applied to audiovisual environments, in which the spectator&#39;s seat is installed in a stepwise shape, such as a stadium and a movie theater. 
     Note that here, the badminton competition venue is described as an example, but the present invention can also be applied to other sports events and the stage production in theaters and the like, when total reflection conditions and the upper limit of the viewing zone can be satisfied and the first display unit  11 , the second display unit  12 , the first optical element  21 , and the second optical element  22  can be installed. 
     As described above, the floating image display apparatus according to the present embodiment includes: the first display unit  11  that is installed to have the display surface facing toward a ground; the first optical element  21  that is installed to be inclined with respect to the ground, transmits a part of the light of the display image A 1  displayed by the first display unit  11 , and reflects a part of the light; the second display unit  12  that is installed to have the display surface perpendicular to the ground; and the second optical element  22  that is installed to be perpendicular to the ground, transmits a part of the light of the display image A 2  displayed by the second display unit  12 , and reflects a part of the light. Accordingly, the multilayer virtual images B 1  and B 2  can be made without installing the second optical element  22  on the stage  30 . 
     Floating Image Display Apparatus of Comparative Example 
     The floating image display apparatus of a comparative example will be described with reference to  FIG.  2   . The floating image display apparatus illustrated in the drawing is a display apparatus in which a plurality of half mirrors  61  and  62  are installed in parallel with each other and the floating image is projected in multiple layers on the stage  30 . The spectator is positioned in a left direction in the drawing of the floating image display apparatus. 
     A display apparatus  51  is installed such that the display surface of the display apparatus  51  is parallel with the ground and faces downward. The half mirror  61  is installed at a position below the display apparatus  51  and inclined at 45 degrees with respect to the ground, and receives light emitted from the display apparatus  51 . When the display apparatus  51  displays the display image A 1 , the light of the display image A 1  is directed toward the half mirror  61 . The half mirror  61  reflects a part of the light of the display image A 1 . The virtual image B 1  is made at a position away by the same distance D F  as the height H from the ground to the display apparatus  51 . The spectator recognizes the virtual image B 1  on the stage  30  as a floating image. 
     A display apparatus  52  is installed on a deeper side of the display apparatus  51  such that the display surface of the display apparatus  52  is parallel with the ground and faces downward. A half mirror  62  is installed at a position below the display apparatus  52  and inclined at 45 degrees with respect to the ground, and receives light emitted from the display apparatus  52 . When the display apparatus  52  displays the display image A 2 , the light of the display image A 2  is directed toward the half mirror  62 . The half mirror  62  reflects a part of the light of the display image A 2 . The virtual image B 2  is made at a position away by the same distance D R  as the height H from the ground to the display apparatus  51 . The spectator recognizes the virtual image B 2  on the stage  30  as a floating image. 
     In the floating image display apparatus of the comparative example, a multilayer floating image can be displayed, but the half mirror  62  for displaying the floating image on the deeper side needs to be installed on the stage  30 . Therefore, the arrangement of the actual object and the performer on the stage  30  is limited. 
     Furthermore, since it is assumed to be viewed from a position in a horizontal direction, the floating image display apparatus of the comparative example is not suitable for a configuration in which the spectator is disposed in a vertical direction. 
     REFERENCE SIGNS LIST 
     
         
           11  First display unit 
           12  Second display unit 
           21  First optical element 
           22  Second optical element 
           30  Stage 
           31 ,  32  Net