Automatic focus adjustment device capable of accurately driving

Details Automatic focus adjustment device capable of accurately driving Automatic focus adjustment device capable of accurately driving

1995-09-01

1998-02-10

Blankenship, Howard B.

Photography

Having variable focal length of camera objective

Power zoom

396 77, 396 86, 396 81, 396 82, 318640, 318652, G03B 310, G03B 300, G03B 1336

Patent

active

057179611

ABSTRACT:
An automatic focus adjustment device which accurately performs end point detection of the range of movement of a photographic lens to smoothly drive the photographic lens completely to a focus position. The automatic focus adjustment device includes a defocus amount detection device to detect a position deviation of the image position of a subject formed by the photographic lens from an image forming plane. An actuation amount necessary to drive the photographic lens by the detected defocus amount is calculated. An actual actuation amount decision device decides whether the actual actuation amount output to drive the lens is within a permissible range predetermined for the drive. A first lens displacement decision device decides whether the lens position changes during a predetermined first time period, and a second lens displacement decision device decides whether the lens position changes during a predetermined second time period when the actual actuation amount decision device decides that the actual actuation amount is outside the permissible range. The actual actuation amount setting device sets the actuation amount used to drive the lens according to the decisions by the first and second lens displacement decision devices.

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