A backlighted display system includes a liquid crystal display, a flat light guide behind the display, and light emitting diodes (LED's). The light guide is a molded slab of clear polycarbonate material with two planes depressed into its rear surface. Four segmented bordering surfaces are approximately...http://www.google.com.au/patents/US4630895?utm_source=gb-gplus-sharePatent US4630895 - LCD lightguide
