Overhead projector

Details Overhead projector Overhead projector

1988-03-29

1989-11-21

Haroian, Harry N.

Optics: image projectors

Temperature control

Blower

353122, 353119, 353DIG5, G03B 2100

Patent

active

048825999

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. In this case, the liquid crystal indicating device is slidable or swingable between a position overlying the writing plate and a position and a position overlying the keyboard.

REFERENCES:
patent: 2529664 (1950-11-01), Roysher
patent: 2944461 (1960-07-01), Howell
patent: 3250175 (1966-05-01), Braun
patent: 4294524 (1981-10-01), Stolov
patent: 4368963 (1983-01-01), Stolov
patent: 4453810 (1984-06-01), Curiel
patent: 4563067 (1986-01-01), Ozeki
patent: 4652101 (1987-03-01), Grunwald

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