Optical: systems and elements – Projection screen – With reflector or additional screen
Reexamination Certificate
2000-10-23
2001-11-27
Mahoney, Christopher (Department: 2851)
Optical: systems and elements
Projection screen
With reflector or additional screen
C359S443000, C359S460000
Reexamination Certificate
active
06324000
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rear projection visualization systems and in particular to a construction which minimizes the visual seam between adjacent screens of a rear projection visualization system.
2. Description of the Prior Art
In numerous industries, rear projection visualization systems have become important visualization and design tools. In such systems, the image is projected from the rear side of a translucent screen, relative to the location of the viewer. This allows the viewer to move as needed in front of the screen without interfering with the projected image and without interfering with the viewer's perception of the projected image. In some situations, more than one screen may be used to display a large melded image because such a single screen would be too large to manufacture in one piece. Other applications, such as screens for more immersive virtual reality systems, require multiple adjacent screens as the images are melded together from multiple projectors to create the desired effects. These systems exhibit enhanced immersiveness when the screens are at angles relative to one another, completely or partially surrounding the viewer.
When melded multiple images are back projected onto two adjacent screens, particularly when those screens are at angles relative to one another, a dark, finite width, “visual seam” is created between the two screens. The darkness in the visual seam is caused by the frames supporting the screens. These frames prevent light, from the projectors, from reaching into the space where the screens meet. The melded images which cross over the two screens are thus interrupted by a dark visual seam which runs the height of the screens. In some constructions, the ends of the screens are bent or radiused around the frames and the frames prevent projected light from entering into these radiuses.
Generally illustrative prior art systems include U.S. Pat. Nos. 5,103,339; 5,400,178; and 5,206,760.
A multi-panel framing system is disclosed in U.S. Pat. No. 5,103,339. The edges of the screens are compressed and fastened between brackets in the front and rear of the screens. While holding the multiple screens securely together, portions of the brackets are visible in the front of the screens leaving a visual seam between the screens.
An alternative approach to join multiple screens and minimize the visual seam is disclosed in U.S. Pat. No. 5,400,178. Here multiple screen panels are adjoined in a lattice framework where the square lattice of screens is installed in an outer frame. While the disclosed structure may minimize the visual seam, it can only be used for a uniformly flat screen. Some applications, such as those for virtual reality systems, require adjacent screens to be angled at less than 180° from each other.
A further alternative approach is disclosed in U.S. Pat. No. 5,206,760 where multiple screens are adjoined with a transparent bracket. The bracket is H-shaped and decreases the missing information in the dark visual seam area by using the bracket as a lens. Similarly to U. S. Pat. No. 5,400,178 described above, this approach can also only be used with screens angled 180° next to each other.
In view of the foregoing limitations and shortcomings of the prior art devices, as well as other disadvantages not specifically mentioned above, it should be apparent that there still exists a need in the art for a construction that minimizes the visual seam between adjacent screens.
It is therefore a primary object of this invention to fulfill that need by providing a construction which reduces the average perceived width of the visual seam between two screens which are at an angle less than 180° relative to each other and to have the visual seam illuminated by channeling light from the projector through a translucent material into the seam.
SUMMARY OF THE INVENTION
Briefly described, these and other objects are accomplished allowing the present invention to provide a multi-screen rear projection visualization system in which the screens are attached to each other in such a way as to reduce the average width of the visual seam.
To achieve the desired results, two screens (supported by frames) are oriented between 0° and 180°, relative to one another, and one of the screens is positioned so as to be offset and in front of the other screen at the location where edges of the screens are adjacent. The offset position of the screens allows the illuminated portion of the forward screen to be visible to the viewer while at least partially obscuring the non-illuminated portion of the other. As a result, the average width of the dark visual seam as seen from all viewing angles is reduced.
In an alternative embodiment, one or both of the frames could be made of a transparent material and formed with a step in the frame which would further permit illumination of portions of the screen immediately adjacent the frame. In a further embodiment, reflective material is secured to the frame, ahead of the step, redirecting additional light into the corner of the adjacent screens.
Accordingly, one aspect the invention is a screen assembly for a rear projection visualization system comprising, a first screen including a translucent sheet supported along a left upright edge by a first frame member, a second screen including a translucent sheet supported along a right upright edge by a second frame member, said first and second screens being adjacent to one another and defining an angle therebetween of less than 180°. The left upright edge of the first screen and the right upright edge of the second screen defining a corner, one of said left and right upright edges being located in an offset position relative to the other of the left and right edges whereby the offset position reduces an average width of a visual seam in the corner when compared with the left and right upright edges being in a non-offset position.
In another aspect, the invention is an improvement in a rear projection visualization system including a computer system for generating image signals coupled to a plurality of projections respectively positioned to back project images onto a plurality of screens. The improvement comprises the screens being adjacent to and defining a corner angle therebetween of less than 180°, a first one of said screens being located in an offset position in front of a front side of a second one of said screens whereby an average width of a visual seam perceivable in a corner between said screens is reduced.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.
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Cruz Magda
Fakespace Systems, Inc.
Harness & Dickey & Pierce P.L.C.
Mahoney Christopher
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