| 摘要 |
A rear projection screen has a lens sheet or optical sheet which have an optical function such as light condensation, light diffusion. The lens sheet or the optical sheet has at least two diffusion layers (diffusion portions) which are spaced from each other in a light transmitting direction as a whole. It is preferable to provide one of the diffusion layers on the surface on the light entering side of the lens sheet or the optical sheet which is provided at the position nearest to the light source and the other diffusion layer on the surface on the light exiting side of the lens sheet or the optical sheet which is provided at the position nearest to the observation side. Further, it is preferable that, among the two diffusion layers, the one near the light source side has a smaller light diffusion degree than the one near the observation side. Further, it is preferable to add different (in refractive index or in average particle diameter) diffusion agents to the diffusion layer near the light source side and the diffusion layer near the observation side.
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