Patent ID: 8783932

Claim:
A planar light source device comprising: a first light source for emitting a first light ray which has a punctate spatial luminance distribution when the first light ray is emitted; a second light source for emitting a second light ray; a first spatial luminance distribution conversion portion for receiving the first light ray, changing the first light ray from the punctate spatial luminance distribution to a linear spatial luminance distribution, and then exiting the first light ray; a second spatial luminance distribution conversion portion for receiving the first light ray having the linear spatial luminance distribution and the second light ray, changing a spatial luminance distribution of the received first light ray and a spatial luminance distribution of the received second light ray to a planar spatial luminance distribution, and then exiting the first light ray and the second light ray as planar light; and an optical element disposed on an optical path from a light emitting surface of the first light source to a light incidence face of the second light source where the first light ray enters, the optical element spreading a divergence angle of the first light ray in the slow-axis direction on the optical path; wherein: the first light ray is a laser light; the second light ray has a divergence angle larger than the divergence angle of the first light ray when the first light ray is emitted from the first light source; and a slow-axis direction of the first light ray entering the second spatial luminance distribution conversion portion is parallel to an outgoing direction of the planar light.