Patent ID: 7616858

Claim:
A light guiding plate being made of a transparent thermoplastic resin and having a first main surface, a second main surface opposed to the first main surface, a first side wall, a second side wall, a third side wall opposed to the first side wall and a fourth side wall opposed to the second side wall, wherein the surface portion of the first main surface is provided with convex portions and/or concave portions, the light guiding plate has a longitudinal-direction length, which is a length from the first side wall to the third side wall, of 40 mm to 130 mm, at least an 80% region of the light guiding plate has a thickness of 0.1 mm to 0.55 mm, the light guiding plate has a flatness of 200 μm or less, the thermoplastic resin has a Q value of 0.5 cm 3 ·second −1 or more, and the thermoplastic resin is an aromatic polycarbonate resin having a viscosity average molecular weight of 1.0×10 4 to 1.5×10 4 .