A transparent rear-projection screen is described where the side facing the projectors has a lens surface for parallelling of the light, and where the front side has vertical upright forerunning lenses to upread the light in a horizontal plane, and where between these lenses there are grooves with a...http://www.google.fr/patents/US4993806?utm_source=gb-gplus-shareBrevet US4993806 - Rear-projection screen
