Camera having a liquid crystal focusing screen

Details Camera having a liquid crystal focusing screen Camera having a liquid crystal focusing screen

1992-08-18

1994-07-26

Perkey, W. B.

354200, 354219, G03B 1302

Patent

active

053330315

ABSTRACT:
A diffusion degree of a focusing screen is changed by applying voltage to the focusing screen since the focusing screen comprises liquid crystal material whose molecules are penetrated onto a polymer network. The diffusion degree is changed according to the selected exposure mode. Brightness of an object, measured through the focusing screen, is corrected on the basis of applied voltage, an open aperture value and an exit pupil length of a photo-taking lens. Furthermore, the applied voltage, namely, the diffusion degree is changed according to the object brightness.

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patent: 4208115 (1980-06-01), Proske
patent: 4435047 (1984-03-01), Fergason
patent: 4441798 (1984-04-01), Watanabe et al.
patent: 4494853 (1985-01-01), Watanabe
patent: 4534639 (1985-08-01), Konishi et al.
patent: 4977424 (1990-12-01), Mukai et al.

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