| 摘要 |
PURPOSE:To completely prevent the destructive accident of a magnetic head due to the magnetic attraction between the magnetic head and a magnetic disk, by detecting the magnetic attraction between the magnetic disk and magnetic head and controlling and stopping the actuation of a spindle motor when the magnetic attraction occurs between the magnetic disk and magnetic head. CONSTITUTION:In case magnetic attraction occurs between a magnetic disk 11 and magnetic head 12, the starting torque of a spindle motor 1 becomes larger than normal one, since the magnetic attraction between the magnetic disk 11 and magnetic head 12 is added to statical frictional force. When the magnetic attraction occurs, the spindle motor 1 cannot be started, because the electric current supplied to the driving winding 2 of the spindle motor 1 from an electric current limiting circuit 8 at the time of starting is set to the normally required minimum. Therefore, a main control circuit 10 cannot get a start signal 100 from a rotation detecting circuit 7 and starts to monitor the set time of a timer 9. When the start signal 100 cannot be obtained even when a preset maximum time has passed, the main control circuit 10 stops the output of a start signal 200 outputted to an output driver 5. |
