| 摘要 |
PURPOSE:To obtain a diffusing function without spoiling the function of a prism piece by laminating a diffusing layer on a transparent layer provided with a prism group which has total reflecting surfaces. CONSTITUTION:The transparent layer 10-1 where many prism pieces 1 each consisting of a total reflecting surface 1A and an incidence surface 1B is provided on a light source side (X), the diffusing layer 10-2 where a diffusing material (e.g. SiO2) is dispersed is provided on an observation side (Y); and the layers 10-1 and 10-2 are integrated. The layer 10-2 can be provided with a lenticular lens surface 1E which extends vertically and light absorbing layers 31 can be provided to valley parts of the surface 1E. In this constitution, light incident on prism pieces 1 from the side X is diverged at a specific angle and reflected by the surface 1A, and its reflected light is fixed in a prescribed direction in the layer 10-1 and then diffused by the layer 10-2. Therefore, a decrease in the quantity of front light on the side Y is eliminated.
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