| 摘要 |
PURPOSE:To erase a magnetic disk in DC at high speed by simultaneously permitting a DC to flow into all magnetic heads and switching a spindle motor to a high speed rotation at the time of the DC erasing. CONSTITUTION:The title device is provided with a whole head DC erasing means to cause a DC to flow simultaneously into all magnetic heads 4 and 5, a rotation number switching means 13 to switch the number of the rotations of a spindle motor 2 to a high speed rotation at the time of the magnetic disk DC erasing and a DC erasing gate signal generating means 11 to execute the DC erasing of a magnetic disk 1 by one circumference regardless of an index signal. Consequently, the DC erasing time of the magnetic disk 1 is mode constant regardless of the number of the magnetic heads 4 and 5, rotation awaiting time is eliminated, the revolution of the spindle motor is switched to high speed and the DC erasing time is shortened. Thus, the magnetic disk DC erasing, which is the pre-treatment to write the servo pattern to the magnetic disk, can be executed at high speed. |
