Overhead projector

Details Overhead projector Overhead projector

1985-04-15

1987-03-24

Haroian, Harry N.

Optics: image projectors

Miscellaneous

353DIG5, 353DIG3, 353DIG4, 353 23, 353 65, G03B 2100

Patent

active

046521011

ABSTRACT:
In an overhead projector comprising a writing plate, and under this arranged Fresnel lens, a light source and an objective carried by a carrying arm, the problem to be solved is to overcome the disadvantages of the state of the art and to provide a possibility for a lecturer to make information retrieved from an electronic information source, for example, a computer or an electronic game, accessible to a large viewer and listener circle. The invention solves this problem thereby, that between the Fresnel lens and the writing plate there are arranged a layer of liquid crystals which are aligned in an electric field and transparent electrodes on both sides thereof, whereby two of the plates or films traversed by the light beam have light polarizing properties.

REFERENCES:
patent: 3576364 (1971-04-01), Zanoni
patent: 3844650 (1974-10-01), Nicholson
patent: 3922667 (1975-11-01), Veda

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