Abstract: An overhead projector comprises a housing having a top comprising a Fresnel lens and a writing plate overlying the Fresnel lens. A light source in the housing directs light up through the Fresnel lens and writing plate. A support arm projecting up from the rear of the housing supports an objective lens and a deflection mirror in position to project light from the writing plate onto a wall or screen. A liquid crystal indicating or display device overlies the writing plate and is spaced from the writing plate to provide an air flow space between the writing plate and the liquid crystal indicating device. A fan or blower in the projector housing draws air through the air flow space between the liquid crystal indicating device and the writing plate to cool the liquid crystal indicating device and also produces air flow in the projector housing to cool the light source and other components in the housing. The projector may also have a computer and keyboard for controlling the liquid crystal indicating device.

Abstract: An overhead projector comprises a housing the upper side of which is closed by a transparent writing plate under which there is a Fresnel lens. A lamp in the housing is provided with a cold light reflector and a condenser lens for directing light upwardly through the Fresnel lens and writing plate. A projection head mounted above the writing plate on a support arm extending up from the rear side of the housing and comprising an objective lens and a deflection mirror directs the light received from the lamp through the Fresnel lens and writing plate onto a projection screen. A liquid crystal display in a frame hingedly mounted on the rear side of the housing can be swung between an operative position overlying, but spaced from the writing plate and an idle position up against the support arm where it is held by a magnet.