Fitzopatrick, Cella, Harper & Scinto
Power focus device in a camera
 A power focus device in a camera has a manually rotatively operated focus ring, a lens driving drive source for driving a focusing lens, and a pulse generating device operatively associated with the rotation of the focus ring to generate a pulse signal conforming to the amount of rotation of the focus ring. A focus ring rotation direction detecting device detects the direction of rotation of the focus ring from the pulse signal, a focus ring rotation amount detecting device detects the amount of rotation of the focus ring from the pulse signal, and a drive direction setting device sets the direction of drive of the lens driving drive source on the basis of the result of the detection in the focus ring rotation direction detecting device. A drive amount setting device memorizes the result of the detection in the focus ring rotation amount detecting device and sets the memorized value as the amount of drive of the lens driving drive source. A drive source control device control the lens driving drive source in accordance with the direction of drive set in the drive direction setting device and the amount of drive set in the drive amount setting device. A reversing device immediately reverses the lens driving drive source, changes the setting in the drive direction setting device, returns the drive amount setting device to its initial state, and immediately reverses the lens driving drive source when the focus ring has been rotatively operated in a direction to drive the lens driving drive source in a second direction when the lens driving drive source is being driven in a first direction. 
Canon Kabushiki Kaisha
G G
G03B G02B
inventional inventional
Kazuhiko Ryuichi
Arakawa Kobayashi