| 摘要 |
PROBLEM TO BE SOLVED: To provide a Fresnel lens sheet, transmissive screen and back projection display device in which a projected video is hardly distorted even in the environment where a humidity change may occur. SOLUTION: In the Fresnel lens sheet, unit total-reflection Fresnel lenses each including an incidence plane and a total reflection plane for totally reflecting and deflecting part or the whole of video light incident from the incidence plane to a desired direction are arrayed on a light incident side. The horizontal length L<SB>1</SB>(mm) of the Fresnel lens sheet, thickness T<SB>1</SB>(mm) of the Fresnel lens sheet and a maximum value A<SB>1</SB>(%) of the elongation rate of the Fresnel lens sheet in humidity absorption satisfies a relation of A<SB>1</SB>≤0.6T<SB>1</SB>/L<SB>1</SB>. Further, the Fresnel lens sheet is composed of a Fresnel lens formation sheet on which the Fresnel lenses are formed and an auxiliary sheet to be stuck on the light emission plane side thereof, thereby improving the efficiency in releasing from a metal die in manufacture of the Fresnel lens sheet. COPYRIGHT: (C)2004,JPO&NCIPI
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