Patent ID: 7850357

Claim:
An optical guide bar comprising: a light exit portion for outputting light; light incident portions, on which light is incident, formed on both ends of the light exit portion; and a reflective portion facing the light exit portion and including a prism pattern that reflects light transmitted through the light incident portions towards the light exit portion, wherein the reflective portion has a shape, which is determined in consideration of an effective light emission width of the light incident portion, so that an intensity of the light irradiated from the light incident portions and incident on the reflective portion is substantially equal at all portions of the reflective portion, wherein, when it is assumed that a direction of an optical axis of the exit light is a y direction, a direction perpendicular to the optical axis is an x direction, a distance from the center portion of the reflective portion to a light incident portion in the x direction is L, and a distance from the center portion of the reflective portion to an end portion of the light exit portion in the y direction is h 0 , the shape of the reflective portion can be represented as y = f ⁡ ( x ) = ( x 2 - L 2 ) [ - ( h 0 L 2 ) + ∑ n = 1 ⁢ ( a n ⁢ x 2 ⁢ n ) ] , where n denotes an integer and a n is a coefficient of a polynomial expression.