Stepping motor and magnetic disc reproducing apparatus using the same

摘要

A stepping motor for use in a magnetic disc reproducing apparatus for causing radial scanning movement of a magnetic head relative to a magnetic disc having many picture information recorded on concentric tracks, comprises a casing, a rotor, stator coils to which current is supplied according to a sequence of phase cycles, and a rotor positions detector which includes two electrically-connected contactors mounted on the rotor, and an annular conductor pattern and an arcuate conductor pattern provided in the casing to make continuous and temporary contact with the respective contactors. The arcuate conductor pattern covers a range corresponding to an angle through which the rotor rotates in a predetermined one cycle among the phase cycles of current supply to the coils.