Patent ID: 7973880

Claim:
An illumination device comprising: a light source; and a transparent substrate comprising a transparent substrate body into which light is introduced through at least one side; a transparent low refractive index layer that is disposed on the substrate body and has a lower refractive index than a refractive index of the substrate body; a transparent high refractive index layer that is disposed on the low refractive index layer and has a higher refractive index than the refractive index of the low refractive index layer; and wherein the low refractive index layer is provided continuously across substantially all of a major surface of the transparent substrate body, and wherein the low refractive index layer has a substantially uniform refractive index across the major surface of the transparent substrate body; wherein the light source is located opposite to the side of the substrate body of the transparent substrate, a reflector is provided on an opposite side of the substrate body from the surface on which the low refractive index layer is disposed, and a light emitting portion is provided on the reflector side of the substrate body and emits the light introduced into the substrate body to the reflector.