A light guiding member guides diffusion light using as a central axis a substantial center of the diffusion light emitted from a light source, and comprises a tapered rod and a pipe. The tapered rod comprises an incident end face, an emissive end face having an area larger than that of the incident end...http://www.google.fr/patents/US7195386?utm_source=gb-gplus-shareBrevet US7195386 - Light guiding member, illumination apparatus, and projector
Light guiding member, illumination apparatus, and projector
