Automatic focussing mechanism for camera - uses long base rangefinder and two signal generators which control rangefinder mirror movement and taking lens drive

摘要

A camera automatic focussing unit uses a long base rangefinder principle, one mirror being fixed and the other movable on an axis. The system uses two drive mechanisms one to drive the rangefinder mirror (2) and the second to drive the camera's taking lens. The system also contains two signal generators for determining the subject distance and transferring the information to the lens. The first signal generator operates the rangefinder and confirms correct focus when both the fixed (1) and movable (2) mirrors receive equal proportions of light (9a, 9b) reflected from the subject into the light receiving network (11a, 11b).