| 摘要 |
<p>Distortion Correction for an Overhead Projector System An overhead projector (27) which projects a distortion-free image onto a vertical screen (32) at an oblique angle above the horizontal plane. In a first embodiment of the invention, a projection lens (28) and mirror (33) are displaced from the center of a transparency stage (30) in the direction of projection and a thin, linear, incrementally-grooved prismatic sheet is positioned parallel to the stage (30) and between the stage (30) and a lighting means (40) to redirect light transmitted through the stage (30) and the transparency to the projection lens (28). In a second embodiment of the invention, the grooved prism (38) is formed as an integral part of the lighting means (40).</p> |
