| 摘要 |
PURPOSE:To project light beams so that the center beam is nearly parallel to the normal of a screen, by using a linear Fresnel lens which has deviation between the optical center and the center of size for light convergence. CONSTITUTION:This screen is made of a light-transmissive base plate which has a linear Fresnel lens shape 12 on the incidence side; and the lens center 13 deviates from the center 14 of the size of the base plate and is about one third from the bottom of the base plate. Therefore, when this transmission type projection screen is used, the projected light beams of incident light beams 16, 17, and 18 which are incident in such a way that the center beam 17 is incident to above a center 14 upward slantingly are refracted in nearly horizontal directions and guided effectively to the position of an observer. |
