| 摘要 |
PURPOSE:To perform desired positional control certainly and effectively by a single kind, by a method wherein magnetic scale information of necessary arbitrary resolving power is made writable and this written positional information is read and detected. CONSTITUTION:A magnetic material having high coercive force is applied to the upper circumferential surface having a predetermined radius of a rotary disc 20 and a magnetic head 10 is arranged at the position opposed to the magnetic material coated surface. A magnetic recording scale is made writable on the upper circumferential surface having the predetermined radius on the rotary disc 20 at a predetermined pitch by a magnetic head 10. At the time of control, the magnetic recording scale (positional information) previously recorded is read by the magnetic head 10 to perform desired positional control. At this time, not only desired magnetic recording scale positional information is written but also positional information necessary for the magnetic recording scale is written as the positional information on the rotary disc 20 to make it possible to also detect a specified position.
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