1988-03-28
1989-03-28
Adams, Russell E.
354402, 3541951, G03B 300
Patent
active
048168599
ABSTRACT:
A zoom lens focusing apparatus for a camera includes a zoom ring for adjusting a zoom lens section of the camera to different magnifications by moving a movable lens assembly therein forward and backward. A cam mechanism couples the zoom ring to the movable lens assembly, so that a change in the focal length of the zoom lens section caused by rotation of the zoom ring, is a logarithmic function of the angle of rotation of the zoom ring. A master lens section of the camera also has a movable lens assembly therein which is movable forward and backward by a driving device. The position of the zoom ring is detected while the movable lens of the zoom lens section moves backward or forward, and a sampling pulse generating circuit produces a pulse corresponding to the position of the zoom ring. A voltage which changes corresponding to the distance of the subject from the camera is applied to a charge-and-discharge circuit and the output thereof is held in a sample and hold circuit. The driving device is driven by the output held to drive the movable lens assembly of the master lens section to thereby attain focusing.
REFERENCES:
patent: 4697891 (1987-10-01), Kawai
patent: 4705380 (1987-11-01), Yamamoto et al.
patent: 4728980 (1988-03-01), Nakamura et al.
patent: 4748509 (1988-05-01), Otake et al.
Fujimori Tomoo
Kitahara Hidehiko
Maruyama Takashi
Ootsuki Katsuhiko
Soya Akihiko
Adams Russell E.
Chinon Kabushiki Kaisha
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