| 摘要 |
A folded, magnifying, front projection arrangement for video displays includes a video image source, such as a flat panel display unit out of the user's field of view, projects its image onto a concave mirror also out of the user's field of view. The video image source is maintained off-axis with respect to the optic axis of the concave mirror and at a distance from the concave mirror between one and two times the distance from the concave mirror to its principal focal surface, which would be the principal focal plane if the concave mirror were a spherical or a parabolic mirror. The concave mirror, in turn, reflects and focuses the light from the video image source onto a projection screen, within the user's field of view, resulting in a magnified image. The distortion of the projected image that would otherwise result from off axis projection is compensated for by maintaining the plane of the video image source at a non-perpendicular angle to the optic axis of the mirror. As a result, the image formed on the projection screen is undistorted and in focus across its full width and breadth. Since the projection screen is not an active element, a small aperture, or hole, can easily be cut through it so that a video camera, for capturing the image of the viewer of the screen, may be positioned behind it. The image resulting from such camera placement provides good eye contact to a remote party viewing the image.
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