Disclosed is a slide projection apparatus convertible for projection of an image either onto a remote surface or onto a screen built into the housing of the apparatus. A door, for selectively blocking the projection path, is coupled with a projection lens supported on a carrier. The lens is alternatively...http://www.google.es/patents/US4030821?utm_source=gb-gplus-sharePatente US4030821 - Rear screen projector with remote projection capability
Rear screen projector with remote projection capability
