1979-02-21
1980-06-17
Gonzales, John
350117, 354155, 354219, G03B 1324
Patent
active
042081157
ABSTRACT:
A focusing screen of a viewfinder system for a photographic camera is designed as a liquid crystal cell having two transparent bodies which lie opposite one another with plane surfaces at a short distance from each other, these plane surfaces carrying electrodes. By applying a current to the electrodes, or by cutting off such current, the character of the focusing screen is changed, providing a single multi-purpose screen and obviating the need to change the screen when focusing for a different type of photography. The liquid crystal screen may be used in conjunction with or may be formed as part of a field lens or a Fresnel lens forming part of the viewfinder system. Various arrangements of the electrodes for changing the character of the screen over only part of the area thereof, rather than the entire area thereof, are disclosed.
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Gonzales John
Rollei-Werke Franke & Heidecke
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