An object of the present invention is to provide a light guide device which can emit light rays of high directivity with high efficiency irrespective of incident angles, and a light source device using the light guide device which can provide light rays of high directivity with high efficiency ...http://www.google.se/patents/US5799126?utm_source=gb-gplus-sharePatent US5799126 - Light guide device, light source device, and liquid crystal display device 
