Mitsubishi Electric Corp developed a display capable of projecting a 56-inch image (886 (W) x 1,120mm (H)) in midair and exhibited it at a meeting that it organized to announce its R&D results Feb 17, 2016.
Viewers can freely pass through an image (video) that the display projects in midair. Mitsubishi Electric expects that the new display will be used for digital signage, amusements, guide signs, etc. The company has been developing the display in the aim of commercializing it in or after fiscal 2020.
There have already been displays that can show an image above a table-like device. And, in demonstrations, images displayed by those displays were touched and penetrated through by a hand. However, because of the table-like device right below the image, it was not possible for a human to walk through the image.
On the other hand, there are displays that are used in theaters, etc and can project an image with a size equivalent to a human in midair. Those displays are used for showing, for example, the virtual images of artists on the stage in concerts. In this case, people on the stage can pass through those images projected in midair. However, the audience cannot approach the images because there is a half mirror physically separating the stage from the seats for the audience.
This time, Mitsubishi Electric expects that an unspecified large number of people will pass through an image projected by the new display. The company designed the optical system so that an image is displayed in front of the half mirror (beam splitter), unlike the displays used in theaters.
The optical system was designed as follows. The half mirror is obliquely placed so that the image of the right screen is reflected to the back, where there is a retroreflective sheet that reflects incident light to the incident direction. As a result, a passable large image can be displayed in midair 1m or more away from the half mirror.
Mitsubishi Electric also displayed "guide images" on walls located to the right and left of the midair image to naturally focus the viewer's eyes on the midair image. The company realized a 90-inch (1,992 (W) x 1,120mm (H)) screen by seamlessly displaying the midair and guide images.