Automatic focus control for camera - has variable angle mirror to reflect received light from subject to photocell

摘要

An automatic focus control for a camera has a measuring beam of light directed at the subject (6) with the reflected beam picked up by a rotating mirror (5) of fset from the axis of the beam. The mirror reflects light to a photocell (2). The angle of the mirror is taken as a measure of the spacing of the subject. A feedback control with phase shift register and flip-flop switching circuits provides a rapid determination of the angle of the mirror corresponding to max. signal, and hence the distance setting. The circuit is designed to reach the setting rapidly without hunting.