Patent ID: 7948579
Filing Date: 2011-05-24
Classification: G02B

Abstract:
1. A planar lighting device using a laser light source, comprising: an optical fiber, of which one end is optically coupled to the laser light source, for propagating, from the one end to another end, a laser light emitted from the laser light source; and a light-guiding plate including a light-guiding section in which a plurality of right prisms of a same shape for extracting the laser light by contacting the optical fiber are arranged parallel to each other in a same direction at equal intervals, and also including a planar section for diffusing the laser light extracted from the light-guiding section and emitting the diffused laser light from one main surface, wherein the optical fiber being bent more than twice to form a plurality of straight line portions arranged in a parallel configuration with respect to each other and with an interval being formed between any two straight lines portions of the plurality of straight line portions, each interval being unequal in width with respect to any other interval, the optical fiber and the light-guiding plate being positioned such that the laser light is extracted at equal intervals from each of the plurality of straight line portions, and the optical fiber is formed such that, of the intervals between any two adjacent straight line portions of the plurality of straight line portions, an interval on a one end side of the optical fiber is widest of the plurality of intervals, and an interval on the other end side of the optical fiber is the narrowest of the plurality of intervals, wherein the intervals become narrower when moving from the one end side of the optical fiber to the other end side of the optical fiber.