| 摘要 |
PROBLEM TO BE SOLVED: To obscure the moire which occurs when two sheets of a Fresnel lens plate and a lenticular plate are superposed on each other by setting the ratio of the pitch of the lenticular plate and the pitch of the Fresnel lens plate so as to be in a range of specific values. SOLUTION: The size at which the moire is invisible of the rear surface projection type screen of the constitution consisting of the lenticular plate on an observation side and the Fresnel lens plate on a projection side is assumed to be about 1 mm and the pitch ratio of both of the lenticular plate and the Fresnel lens plate at which the size of the moire is about 1 mm or below is determined. The range of the conventional pitch ratio at which the moire is invisible exists near 1.4, 2.4 and 3.4, but when the pitch ratio of the Fresnel lens plate is set at a range of 1.57 to 1.62 or 1/1.57 to 1/1.62 when the pitch ratio of the lenticular plate is set at 1, the size of the moire, at which the moire is obscure even if the size is not within the range of the conventional pitch ratios, may be reduced to <=1 mm.
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