Patent ID: 8837009

Claim:
A rod-shaped light guiding member that guides light in a longitudinal direction thereof, the light guiding member comprising: an input surface being an end face of the light guiding member, the input surface being a surface on which light is inputted; an output surface in a periphery of the light guiding member, the output surface having a belt-like shape, extending in the longitudinal direction, and being a surface from which light is emitted; and a counter surface in the periphery of the light guiding member, the counter surface being opposite the output surface, wherein the output surface has a belt-like diffusing portion extending in the longitudinal direction, the diffusing portion being configured to diffuse light emitted from the output surface, the counter surface has a belt-like reflective portion extending in the longitudinal direction, the reflective portion being configured to reflect light toward the output surface, a width of the diffusing portion in a direction orthogonal to the longitudinal direction is smaller than a width of the reflective portion in the direction orthogonal to the longitudinal direction, the diffusing portion has a plurality of ridges extending in the longitudinal direction and arranged in the direction orthogonal to the longitudinal direction, and the plurality of ridges each have a round cross-sectional shape orthogonal to the longitudinal direction.