| 摘要 |
PROBLEM TO BE SOLVED: To provide a light diffusion sheet, and to provide a projection screen using the sheet. SOLUTION: A plurality of unit lenses formed in a one-dimensional or two-dimensional direction is provided with an entire reflection part in which part of incident light entirely reflects on the inner face, a highly refractive index is formed of a material having a prescribed refractive index N1, and a lowly refractive index filled with a material having a prescribed refractive index N2 is formed between the adjacent unit lenses. Further, the cross sectional shape of the unit lens is substantially trapezoidal, a lower bottom of the trapezoid is an incident part, oblique sides are the entire reflection part, and an upper bottom is an emission part. When the oblique side making the entire reflection part makes an angle making a normal of the emission partθ,θis constituted to have specific relation of N1 and N2, the cross sectional shape of the lowly refractive index sandwiched by the adjacent unit lenses is substantially triangular, the edge of the emission part is a curved shape having prescribed curvature or substantially trapezoidal, and the upper bottom of the incident part has a shape in parallel or tilted to the lower bottom. COPYRIGHT: (C)2005,JPO&NCIPI
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