Patent ID: 7771104

Claim:
A planar lighting device comprising: a light guide plate including: a light exit plane being flat and rectangular, for emitting planar light; four light entrance planes, each for admitting light traveling parallel to said light exit plane, and each being formed along each of four sides of said light exit plane; and a pair of rear planes being formed on a side opposite from said light exit plane and inclined such that a thickness of said light guide plate in a direction perpendicular to said light exit plane grows thicker with an increasing distance from each of a pair of opposite light entrance planes in said four light entrance planes and joining each other in a middle between said pair of opposite light entrance planes; and four light sources, each for emitting each of said four light entrance planes and for admitting the emitted light through said four light entrance planes, and each being disposed opposite each of said four light entrance planes of said light guide plate, wherein each of said four light sources has LED chips and a support for supporting said LED chips, and wherein said LED chips of each of said four light sources are arrayed on a plane of said support facing each of said four light entrance planes in a longitudinal direction of each of said four light entrance planes.