Patent ID: 9075171
Filing Date: 2015-07-07
Classification: G02B

Abstract:
1. A surface light source device comprising: a light source; and a light guide plate configured to introduce light emitted from the light source through a light incident surface to output the light to an outside through a light exit surface, wherein the light source is provided at a position facing the light incident surface of the light guide plate, the light guide plate includes a light introduction part configured to trap the light that is emitted from the light source and incident through the light incident surface, and includes a light guide plate body that is provided so as to be continuously joined to the light introduction part, a thickness of the light guide plate body being smaller than a maximum thickness of the light introduction part, the trapped light being output to the outside through the light exit surface by a light exit part, the light introduction part includes an inclined surface in at least one of a surface on a light exit side of the light guide plate and an opposite surface thereof, the inclined surface being inclined from a surface in a portion having a thickness larger than the thickness of the light guide plate body toward an end of a surface of the light guide plate body, and the light guide plate body includes a directivity conversion pattern in a region located between the light introduction part and an effective lighting region of the light guide plate body in at least one of the surface on the light exit side of the light guide plate and the opposite surface thereof, the directivity conversion pattern converting a directivity direction of the light passing from the light introduction part to the effective lighting region such that an angle formed by the directivity direction of the light and a direction perpendicular to the light incident surface decreases when viewed from a direction perpendicular to the light exit surface.