Rotation detector

摘要

A rotation detector resists magnetic disturbances from sources near the detector. The rotation detector includes a rotor on which iron magnetic path changing pieces are fixed at predetermined intervals. A first bias magnet and a first magneto-resistive element for detecting the flux of the first bias magnet oppose the magnetic path changing pieces. A magnetic guide plate is located to guide disturbing magnetic flux in predetermined directions. The disturbing magnetic flux thus fails to adversely affect the first magneto-resistive element.