Patent ID: 8714770

Claim:
A lighting device comprising: an elongated flat substrate; a plurality of semiconductor light sources arranged on the flat substrate at a predetermined interval in a longitudinal direction of the flat substrate; a lens plate disposed to face the semiconductor light sources, the lens plate including a lens-light-incident surface and a lens-light-emitting surface, light emitted by the semiconductor light sources being incident into the lens-light-incident surface, and the lens-light-emitting surface having a lens thickness defined between the lens-light-incident surface and the lens-light-emitting surface; a base frame engaging with the lens plate so that the flat substrate is disposed between the lens plate and the base frame; a first lens section located on one of the lens-light-incident surface and the lens-light-emitting surface and configured to distribute the light emitted by the semiconductor light sources in the longitudinal direction; and a second lens section located on the other one of the lens-light-incident surface and the lens-light-emitting surface and configured to distribute the light emitted by the semiconductor light sources in a width direction which is orthogonal to the longitudinal direction, the second lens section including a concave portion formed in the width direction which is orthogonal to the longitudinal direction, wherein the first lens section includes a curvature surface unit including a plurality of convex section curvature surfaces having different curvature radii and formed adjacent in the longitudinal direction, each of the convex section curvature surfaces being disposed inside a projected area of a respective one of the semiconductor light sources in the longitudinal direction.