Patent ID: 9708847
Date: 2017-07-18
CPC Classifications: B29C,B29D,B29K,B29L,E06B,F21S,G02B

Claim:
1. A daylighting sheet that is arranged in an opening portion of a building and transmits light from an outdoor side to an indoor side, wherein the daylighting sheet is formed by stacking a plurality of layers, the layers include: light deflection portions that are formed between the light transmission portions and filled with a material whose refractive index is lower than that of the light transmission portions, and wherein on a cross section in a thickness direction, assuming that an angle formed by a line connecting a position at the top side that is closest to the base material layer and a position at the top side that is opposite to the position closest to the base material layer, together with a normal to a layer surface of the base material layer is γ, and that an angle formed by a side of the portion upward that is farthest from the base material layer together with the normal is β, the angle β is no less than the angle γ and no more than 40°, assuming that an angle formed by a side of the portion downward that is closest to the base material layer together with the normal is η, the angle η is no less than the angle β, assuming that distance of the side forming the angle n in the thickness direction is J, a pitch of the light transmission portion is P, and an angle formed by a bottom side of the light transmission portion in a position where the daylighting sheet is arranged in the opening portion of the building, together with the normal is α, the refractive index of the light transmission portion is n, and the formula J=Ptan(π/2−2α−arcsin(1/n)) is satisfied, 0.7S≦J≦0.9S.