Birch, Stewart, Kolasch & Birch
Zoom lens focusing apparatus
 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. 
Chinon Kabushiki Kaisha
G
G02B
inventional
Tomoo Akihiko Hidehiko Katsuhiko Takashi Osamu
Fujimori Soya Kitahara Ootsuki Maruyama Watanabe