Patent ID: 8419264
Filing Date: 2013-04-16
Classification: G02B

Abstract:
1. A planar lighting device comprising: a light source that emits light; and a light guide plate disposed opposite said light source in which light emitted from said light source enters and is emitted therefrom as planar light, wherein: said light guide plate comprises a flat light exit plane that emits said planar light, a light entrance plane that is formed opposite said light source and includes one side of said light exit plane, an end plane that includes the opposite side to said one side of said light exit plane, and a rear plane formed on the side opposite said light exit plane; said rear plane comprises a first rear plane that is joined with said end plane and is smoothly inclined to said light exit plane so that the distance from said light exit plane increases as the distance from said end plane increases, and a second rear plane that is joined with said first rear plane, is joined with said light entrance plane and is smoothly inclined to said light exit plane so that the distance from said light exit plane increases as the distance from said light entrance plane increases; said first rear plane and said second rear plane are joined so as to form a joining line where the distance from said joining line to said light entrance plane is shorter than the distance from said joining line to said end plane, and the distance between said light exit plane and said rear plane is greatest at said joining line; said light guide plate is formed so that a part on the side of said first rear plane closer to said joining line and a part on the side of said second rear plane closer to said joining line each have a curved shape with an arbitrary point on a plane that passes through said joining line and is orthogonal to said light exit plane as its center; said light guide plate satisfies the inequality R said light guide plate includes a plurality of scattering particles in its interior.