| 摘要 |
PROBLEM TO BE SOLVED: To provide a light guide plate which controls an emission angle of an incident light beam and make sunlight reach a back of a room with a terrace in winter as a roof material of the terrace.SOLUTION: A prism surface 3 is arranged on at least one side of a transparent resin plate 2, wherein the prism surface 3 has a structure formed by sequentially arranging unit prisms 3a, each of which is a triangular prism having a triangle cross section in a width direction, side by side. One base angle α of the triangle cross section of the unit prism 3a for structuring the prism surface 3 is 3-9°, and another base angle β is 60-90°. |
