Optics: motion pictures – Panoramic picture type
Reexamination Certificate
2000-03-17
2001-12-04
Adams, Russell (Department: 2851)
Optics: motion pictures
Panoramic picture type
C348S036000
Reexamination Certificate
active
06327020
ABSTRACT:
TECHNICAL FIELD
The invention relates to a full-surround spherical screen projection system that projects recorded images or computer graphic images, and particularly to a full-surround spherical screen projection system that can be used to project scenery of cities, housing spaces, flight simulators, game apparatuses and planetariums.
BACKGROUND ART
Recently, as a virtual reality visual display system that can give presence—the same feeling as if placed in a real situation—an immersive projection display which encloses viewers with a large screen projected in from the back has drawn attention. A sphere is an ideal shape for an immersive screen in that a distance from the viewer's eye to the projected images remains constant.
As a solid angle subtended by an image with respect to a viewer becomes larger, it is impossible to project the image sufficiently. Therefore, conventionally, from a plurality of plane screens was formed a polyhedral screen, on which the images recorded by a plurality of wide angle cameras corresponding to the plane screens were thrown by projectors.
However, when a plurality of cameras arc used, there is a dead angle between adjacent cameras that does not allow recording. The dead angle may be negligible with respect to a subject in the distance, but as for a subject close by, the image of the subject corresponding to the distance between the edges of the lenses of adjacent cameras is missing.
The structure in a combination of plane screens produces a problem in that the ridges in the seams of each screen give an unnatural impression. In CG (Computer Graphic) images, a geometric correction is made to cope with the problem. Making a correction of recorded images, especially motion images, is difficult in original formatting stages. To do this, a plurality of cameras arc needed and it takes time to correct the original images, which increases cost.
To solve, in principle, the problems of the dead angle and seams, it is necessary to obtain the images of a large solid angle by a single-system camera and project them onto a spherical screen by a single-system projector. Conventionally, as a means of a single-system projector throwing images on a spherical screen, fisheye lenses were used to throw image onto a semi-spherical screen. Yet, since the means produces a shadow when a viewer enters a semi-sphere projection screen, a viewer must view the screen from the outside of the semi-sphere, indicating that, in principle, enclosing a viewer at a solid angle of more than 2&pgr; is impossible. As a result, the means is not suitable to an immersive projection display.
In addition, a means can be thought of that, by a computer, controls, moves and tilts a reflecting mirror for the light from one projector to project in a wide range of angles onto a spherical screen. Yet that system cannot project entirely onto a spherical surface, and the structure is complex and expensive.
It is an object of the invention to solve the problems in the prior art. There is provided a full-surround spherical screen projection system that forms a spherical screen inside of a sphere, places a single-eyed projector, over a viewer, for projecting images in the inner direction of the sphere, provides, inside of the spherical screen, a first reflecting mirror opposed to the projector, provides a second reflecting mirror adjacent to the projector, and projects the images through the first and second reflecting mirrors from the projector on the screen. The screen projection system can throw images on the entire surface of the spherical screen except for the top and bottom of the sphere, with a wide visual field angle to the upper and lower directions and without casting a shadow by the viewer. The screen projection system is simple in structure, low in cost and spacious for the viewer.
The full-surround spherical screen projection system can be used to throw recorded images and CG images. At the stage of making original images to be thrown, distortion may be added to the original images beforehand. When thrown onto the spherical screen, the distortion of the images will be cancelled out to produce images without distortion.
DISCLOSURE OF INVENTION
To solve the problems, the invention provides a full-surround spherical screen projection system comprising a spherical screen formed inside of a sphere, a projector for projecting light toward the inside of the sphere, a first reflecting mirror constituting either a plane mirror or a concave mirror, placed above the center of the sphere inside of the sphere, for reflecting the light toward the outside of the sphere, and a second reflecting mirror constituting a convex mirror reflecting the light from the first reflecting mirror to the spherical screen, whereby the light from the projector is thrown on the entire surface of the spherical screen through the first and second reflecting mirrors.
The sphere may have an opening at a portion thereof, and the second reflecting mirror is placed in opposed to the opening within a radius from the center of the sphere.
The projector and the first and second reflecting mirrors are placed on the same optical axis, and the second reflecting mirror is either a circular reflecting mirror with a central hole that passes the light through from the projector or a half mirror.
The projector and the second reflecting mirror may be placed apart to the side along the inner wall of the sphere.
The projection system is used to throw images recorded by a projector or computer-generated images. The recorded images are made by a recorder comprising an elliptical convex mirror according to a curvature of the second reflecting mirror, a subject being recorded through the elliptical convex mirror.
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patent: 3740469 (1973-06-01), Herndon
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patent: 4246603 (1981-01-01), Wolff
patent: 4421486 (1983-12-01), Baldwin
patent: 4464029 (1984-08-01), Jaulmes
patent: 4656506 (1987-04-01), Ritchey
patent: 373638 (1964-01-01), None
Adams Russell
Fuller Rodney
Iwata Hiroo
Knobbe Martens Olson & Bear LLP
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