A display device including liquid crystal display panels, arrays of convergently transmissive elements for forming an erect and real image, and fresnel lenses for magnifying the image. The configured surface of the fresnel lens is arranged on the light incident side. The configured surface includes periodic...http://www.google.es/patents/US6211932?utm_source=gb-gplus-sharePatente US6211932 - Fresnel lens and liquid crystal display device
