An illuminated display device includes a housing having front and rear openings with which to register outer transparent face plates and superimposed inner thermoplastic translucent sheets having inwardly convex, relatively thin thermoformed logos projecting inwardly. The logos are preferably hemispheres...http://www.google.es/patents/US3978599?utm_source=gb-gplus-sharePatente US3978599 - Illuminated display device
