| 摘要 |
PURPOSE:To suppress an influence of a demagnetization and to obtain a rotation detector which expects an increase in its output even in a long wavelength range by alternately providing magnetizing parts and unmagnetizing parts on an Almite vertically magnetized film to be written with magnetic information. CONSTITUTION:A pulse signal for detecting the rotating speed of a capstan shaft 1 is written in a magnetic recording part 3. Magnetized parts 6 and unmagnetized parts 7 are sequentially alternately provided along a circumferential direction at a predetermined interval on the part 3. Accordingly, the part 7 is provided between the parts 6 and 6, and influence of a reverse magnetic field from the part 6 adjacent to the part 6 is suppressed by the part 7. Accordingly, its demagnetizing operation is suppressed, its output is remarkably improved, and an output can be enhanced even in a long wavelength range. |
