Optical apparatus including diaphragm device

Details Optical apparatus including diaphragm device Optical apparatus including diaphragm device

1992-07-08

1994-01-11

Perkey, W. B.

G03B 700

Patent

active

052786056

ABSTRACT:
An optical apparatus having a diaphragm device includes an optical system having a focal length which can be varied, a detecting circuit for detecting the focal length of the optical system, the diaphragm device having an amount of opening which can be varied by means of a motor serving as a drive source, a fixed opening being formed in the diaphragm device, a decision circuit for determining the amount of stopping-down for the diaphragm device, and a control circuit for controlling the amount of driving of the motor of the diaphragm device on the basis of a detection result provided by the detecting circuit and the amount of stopping-down determined by the decision circuit. The control circuit causes the diaphragm device to perform preliminary diaphragm driving from an initial state on the basis of the detection result provided by the detecting circuit, and also to perform stopping-down driving after the preliminary diaphragm driving on the basis of the amount of stopping-down. If the detecting circuit detects a specific focal length, the preliminary diaphragm driving is performed until the diaphragm device forms an opening which is reduced with respect to the fixed opening of the diaphragm device.

REFERENCES:
patent: 4159864 (1979-07-01), Yasukuni et al.
patent: 4245901 (1981-01-01), Karikawa et al.
patent: 4299459 (1981-11-01), Mizokami
patent: 4423937 (1984-01-01), Suzuki et al.
patent: 4478502 (1984-10-01), Nakai
patent: 4696560 (1987-09-01), Ogihara et al.
patent: 4857952 (1989-08-01), Fukushima et al.
patent: 4998129 (1991-03-01), Watanabe et al.

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