Patent ID: 8345186
Filing Date: 2013-01-01
Classification: G02B

Abstract:
1. An illumination device including: a spot-shaped light source; a light guide arranged to diffuse and surface-emit light from the light source; and a substrate arranged to fixedly dispose the light source and the light guide thereon; wherein the spot-shaped light source is arranged to face an edge surface of the light guide; a light flux emitted from the spot-shaped light source: (I) enters the light guide at a critical angle of θ, and (ii) spreads radially inside the light guide at the critical angle of θ, such that a first area and a second area are defined in a light-guiding section of the light guide; the first area is included in the light flux to spread radially inside the light guide at the critical angle of θ and the first area is a light path of the light emitted from the spot-shaped light source; the second area is arranged outside of the light flux and is positioned such that it is not a light path of the light emitted from the spot-shaped light source; in the first area, a first portion of a back side of the light guide is spaced away from and is not in contact with the substrate; in the second area, a second portion of the back side of the light guide is in contact with the substrate; the substrate is connected with the second area of the light-guiding section of the light guide so as to fix the light guide on the substrate; a light-emitting surface of the light guide is parallel to the second portion of the back side in a direction extending from the spot-shaped light source to the light-emitting surface in a plan view; the first area is oblique with respect to the light-emitting surface; and the illumination device further includes a plurality of the spot-shaped light sources and a plurality of the light guides, respective pairs of the plurality of the spot-shaped light sources and the plurality of the light guides are arranged such that light-emitting sections of the plurality of the light guides are arranged on top of light-guiding sections of an adjacent one of the plurality of the light guides.