METHOD FOR DETECTING ABSOLUTE POSITION BY USE OF ENCODER, AND ENCODER

摘要

A code plate (1) is attached to the shaft of an object to be detected. The rotation of this plate is detected to generate one-turn signals and increment signals representing a fraction of rotation, formed by equally dividing one turn. The absolute position is measured by use of an ecoder having a counter (15) which counts the incremental signals. The counter (15) is cleared by the first one-turn signal (Z) generated after the encoder starts to operate. After the counter (15) is cleared, it counts up incremental signals with the rotation of the shaft of the object. However, the counter (15) is not cleared by the one-turn signals other than the first one. In this way, the counter (15) provides a value corresponding to the distance between the position where a one-turn signal is received and the position to be measured.