Patent ID: 8052315
Filing Date: 2011-11-08
Classification: G02B

Abstract:
1. A planar illumination device comprising: a first light source and a second light source which are arranged at predetermined intervals; a light guide plate which is arranged between the first light source and the second light source and has: guide reflection plates which are arranged on a light exit surface side of the light guide plate and on a rear surface side of the light guide plate with respect to each of the first and second light incident surfaces of the light guide plate and which guide the light emitted from the first and second light sources to the first and second light incident surfaces, respectively, wherein a cross section on a plane perpendicular to the side, of the rear surface of the light guide plate has a curved line in which a distance from the light exit surface to the rear surface of the light guide plate along a direction normal to the light exit surface increases with a shift from the first light incident surface and the second light incident surface to a center of the light guide plate, an inclined angle relative to the light exit surface reduces with a shift from the first light incident surface or the second light incident surface to the center, and the inclined angle relative to the light exit surface is zero degrees at the center, wherein the first and second light sources have respective light emitting surfaces longer in length in a second direction substantially orthogonal to the light exit surface than effective cross sections of the first and second light incident surfaces obtained by projecting the first and second light incident surfaces of the light guide plate onto an orthogonal plane substantially orthogonal to the first direction and which are arranged such that the light emitting surfaces are inclined at a predetermined angle relative to the orthogonal plane and the light emitting surfaces are located toward the first and second light incident surfaces of the light guide plate, respectively, wherein the guide reflection plates include a first guide reflection plate attached to an end portion of the light exit surface of the light guide plate and a second guide reflection plate which is attached to an end portion of the inclined surface of the light guide plate and has an extension portion extending from an edge of the inclined surface to an outside of the inclined surface, and wherein the light emitted from the first and second light emitting surfaces of the first and second light sources are allowed to enter the first and second light incident surfaces of the light guide plate, converted into the planar light, and emitted as the planar light from the light exit surface.