| 摘要 |
PURPOSE:To prevent the damages of a magnetic disk and a magnetic head, by providing a single notch in the moving body such as the magnetic body and discriminating a pattern by the output which is obtained by said notch through a plurality of detecting elements. CONSTITUTION:The single notch 6 is formed at the peripheral part of the magnetic disk 1 so as to form the specified pattern. A plurality of the detecting elements 7 and 8 are provided in parallel at the peripheral part of the magnetic disk 1, with a specified interval being provided. When the magnetic disk 1 is rotated in the normal direction shown by the arrow or in the reverse direction, the notch 6 passes in the order of said detecting elements from 7 to 8 or from 8 to 7. In this constitution, the number of rotation of said moving body can be detected only when the movement in the normal direction is performed, the magnetic head is not contacted with the surface of the magnetic medium of the magnetic disk, and the damages do not occur on both the disk and the head. |
