Patent ID: 8220975

Claim:
A plate-shaped lens member, configured to have concentric annular prisms each including an inner annular surface divided from a light-entrance surface of a TIR lens and an outer annular surface divided from a light-reflection surface of the TIR lens in which the light-entrance surface has a concave shape provided at a lower portion of the TIR lens and the light-reflection surface has a convex shape positioned outside of the light-entrance surface, the plate-shaped lens member comprising: a light source-facing surface having a concave shape and disposed to face a light source; and a light-exit surface opposite to the light source-facing surface, the concentric annular prisms each including the inner annular surface and the outer annular surface that is positioned outside of the inner annular surface to form each of the prisms, the concentric annular prisms provided on the light source-facing surface, wherein in divided portions of the light-reflection surface of the TIR lens, the divided portions positioned away from a central axis of the TIR lens are allocated to the outer annular surfaces of the concentric annular prisms that are positioned adjacent to a central axis of the plate-shaped lens member, the central axis of the plate-shaped lens member corresponding to a central axis of the light source-facing surface, and the light source-facing surface having a Fresnel lens surface fresnel-ized from the TIR lens, the Fresnel lens surface comprising the concentric annular prisms centered on the central axis, and each of the concentric annular prisms including the inner annular surface and the outer annular surface, the inner annular surface positioned closer to the central axis than the outer annular surface, and in each of the concentric annular prisms, the outer annular surface being a total-internal-reflection surface that totally internally reflects on the outer annular surface light received through the inner annular surface.