Patent ID: 8457455
Filing Date: 2013-06-04
Classification: G02B

Abstract:
1. A light guide comprising: a core made of a material having translucency; and a clad made of a material having an index of refraction different from an index of refraction of the core and surrounding a periphery of the core, wherein a light incident surface and a light exit surface, which are end faces of the core and the clad, are formed as inclined surfaces so that an orthogonal projection to a plane orthogonal to an extending direction of the light guide has a rectangular shape and being inclined at a predetermined angle in a direction of moving away from the end face; wherein a light applied from a light source being introduced into the core by being reflected at the light incident surface and a light transmitted through the core being exit to outside by being reflected at the light exit surface; wherein at least one of the light incident surface or the light exit surface of the core is arranged while shifted in parallel without changing respective inclined angles so that the inclined surface is divided into a plurality of inclined flat surfaces parallel in a longitudinal direction of the rectangular shape in the orthogonal projection and the plurality of inclined flat surfaces closer to the light source are positioned in a direction of moving away from the end face to be in a shape extending in the direction of moving away from the end face in a stepwise manner as a whole; and wherein the plurality of inclined flat surfaces are discontinuously arranged with each other via other flat surfaces having a different inclined angle.