Patent ID: 8613531

Claim:
A light emitting device comprising: a substrate; a light emitting element provided on the substrate; and a light guiding member comprising: a light incoming surface where light emitted from the light emitting element enters; a launching surface from which light entering the light guiding member through the light incoming surface is launched; wherein the light guiding member is configured such that a portion of the light emitted by the light emitting element is reflected or refracted so as to illuminate an area on a side of the substrate opposite to the light emitting element; the launching surface comprises a curved surface and a side launching surface; a center of curvature of the curved surface is provided at a position opposite to the light emitting element; the curved surface is configured such that a portion of the light emitted by the light emitting member, entering the light guiding member through the light incoming surface, and reaching the curved surface without otherwise being refracted or reflected, is totally reflected by the curved surface; the curved surface is configured such that light emitted from the light emitting element and totally reflected by the curved surface is directed toward the side launching surface; the side launching surface is configured as a slope that is tilted so as to become closer to an optical axis of the light emitting device as a slope location becomes further away from the substrate and has a curved form that swells out in a direction departing from the optical axis, such that light totally reflected by the curved surface and incident on the side launching surface is refracted in a direction toward a plane defined by a surface of the substrate, such that an angle between the refracted light and an optical axis of the light emitting device is less than an angle between the refracted light and a direction perpendicular to the optical axis of the light emitting device; and a circular groove is formed in the light guiding member at the surface opposite to the curved surface around the optical axis of the light emitting device such that light totally reflected by the curved surface and further totally reflected by the side launching surface is reflected toward the side launching surface and launched through the side launching surface.