Patent ID: 7771102
Filing Date: 2010-08-10
Classification: G02B

Abstract:
1. A planar lighting device comprising: a light guide plate including a light exit plane being flat for emitting planar light, a pair of light entrance planes, each for admitting light traveling parallel to said light exit plane, and each being formed along each of a pair of opposite sides of said light exit plane, and rear planes 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 said pair of light entrance planes and joining each other in a middle between said pair of light entrance planes, and a pair of light sources, each for emitting the light to each of said pair of light entrance planes and for admitting the emitted light through each of said pair of light entrance planes, and each being disposed opposite each of said pair of light entrance planes of said light guide plate, wherein each of said pair of light sources has LED chips and a support for supporting said LED chips, wherein said LED chips of each of said pair of light sources are arrayed on a plane of said support facing each of said pair of light entrance planes at a varying array density in a longitudinal direction of each of said pair of light entrance planes, and wherein said varying array density of said LED chips is highest in a position opposite a central portion of each light entrance plane in the longitudinal direction thereof and decreases with an increasing distance from said central portion to form an illuminance distribution of the light emitted through said light exit plane into a bell-curve distribution where illuminance gradually increases toward a central portion of said light exit plane in the longitudinal direction of each light entrance plane and is highest in the central portion of said light exit plane in the longitudinal direction.