| 摘要 |
<p>A transparent rear-projection screen assembly consists of a rearmost Fresnel lens sheet (7a), an intermediate screen (7b) having on its front and rear sides parallel vertical rows of convex lenses (9, 10) and having vertical ridges (11) with their tops covered by light-impermeable materials (12), and a foremost screen (7c). To the rear side of the Fresnel lens sheet red, green and blue pictures are projected from projectors (1, 2, 3). The rear side of the foremost screen has parallel convex lenses (71) the focal points (76) of which are located in the front side of the foremost screen. The front side of the foremost screen (7c) is composed of parallel ridges (72) separated by deep recesses (74) of triangular cross section so that the thickness of each ridge (72) gradually decreases towards its top (73). The flanks of each ridge (72) are covered with a light-impenetrable material (75) while the top (73) of the ridge is not covered to allow light to pass therethrough. The dimensions of the ridges (72), the recesses (74) and so on are determined relative to each other so as to prevent decrease of contrast due to light rays which are transmitted through the front side into the foremost screen and reflected back to the outside after internal reflection.</p> |
