| 摘要 |
PURPOSE:To obtain a clear image with high contrast even in a bright room, by providing a transparent plate on which many minute faces are formed, on the surface, and forming an opaque layer having a nonreflective surface, on the minute face which does not cross an optical path of a diffusion layer going to a position for observing a projected image, among said minute faces. CONSTITUTION:In an example in which a minute face is formed in one side only of a transparent plate 1, and a diffusion surface 4 is formed in one side of the transparent plate 1, projected light from a projecting device passes through the minute face 3 and diffused by the diffusion surface 4 as indicated with a one point chain line, and this diffused light passes through the minute face 3 again and emitted from a screen, and goes to a position for observing a projected image. On the other hand, the greater part of external light from the peripheral environment is shielded by an opaque layer 2 and does not reach the diffusion surface 4. That is to say, the greater part of a light beam passing through the transparent plate 1 is occupied by projected light from the projecting device and its diffused light. In such a way, a black level of the projected image which is formed on the diffusion surface 4 is kept low even in case it is used in a bright environment, and a distinct image with high contrast is obtained.
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