Encoder for detecting forward and reverse rotations for use in photographic camera

摘要

The encoder includes a rotatable shaft (A), at least two disks (59a,b) provided to rotate with it. Each disk is formed with a respective set light modulating pattern, and a respective photo-coupler is associated with each disk to detect the respective light modulating pattern. The angular relationship between the disks is selected to provide, on its rotation, output signals from the photocouplers which have a set phase difference enabling detection of the direction of rotation of the rotatable shaft. The angular relationship between the disks is selected to provide the output signals with a set phase difference of a quarter phase. The disks are formed with the same light modulating pattern e.g. as light transmitting slots (S) arranged at constant angular intervals in non-transmitting surface of the disc.