DIFFUSION SHEET, TRANSMISSION SCREEN HAVING THE SAME, DIFFUSION SHEET MOLD MAKING METHOD AND DIFFUSION SHEET PRODUCING METHOD

摘要

On a diffusion sheet (101), a plurality of substantially trapezoidal prismatic unit lenses (11) are arranged so that their longer axes are parallel to each other and so that planes corresponding to longer bottom sides (112) in the substantially trapezoidal cut surfaces of the unit lenses (11) all lie on a light incidence plane. Further, a groove between adjacent unit lenses (11) is formed with a light absorbing section (12) for absorbing and/or blocking the outside light coming in from the light going-out side. In such diffusion sheet (101), the light incident on each unit lens (11) from the light going-out side is totally reflected on a plane corresponding to the lateral side (111) in the substantially trapezoidal cut surface normal to the longer axis of each unit lens (11) and goes out from the light going- out side. In this case, in each unit lens (11), the distance (h) between both bottom sides (112, 113) in the substantially trapezoidal cut surface is from 120% to 400% of the length (p) of the longer bottom side (112) (h/p = 1.20 - 4.00).