US Patent 8109666 Light guiding member and linear light source apparatus using same

A light guide member of the present invention is made of a light transmitting material. The light guide includes a light emitting surface 13, which extends in direction x and includes a lens surface 31 for converging light in direction y. The light guide also includes a light incident surface 11 provided at one of the ends spaced from each other in the direction x. The light emitting surface 13 includes a transitional region 13a adjacent to the light incident surface 11, where the transitional region includes the lens surface 31 and a round pillar surface 32. In the transitional region 13a, the lens surface 31 becomes less dominant in area as proceeding in the direction x toward the light incident surface 11.