Patent ID: 6937429
Filing Date: 2005-08-30
Classification: G11B

Abstract:
1. A magnetic disk storage apparatus comprising: a first motor for rotating a magnetic disk; a magnetic head for reading information from storage tracks on the magnetic disk rotated by the first motor; a second motor for moving the magnetic head over the magnetic disk; a second motor driving control circuit for controlling a movement of the magnetic head by controlling drive currents of the second motor; a back electromotive force detecting circuit; a brake control circuit; and a retract control circuit, wherein the brake control circuit includes a first comparator; and a second comparator, wherein a first threshold voltage corresponds to a first preset speed of the magnetic head in a first direction being inward of the magnetic disk, and a second threshold voltage corresponds to a second preset speed of the magnetic head in a second direction being outward of the magnetic disk, wherein the first threshold voltage is inputted to a first input terminal of the first comparator, the second threshold voltage is inputted to a second input terminal of the second comparator, and a first back electromotive force of the second motor is inputted to a third input terminal of the first comparator and a fourth input terminal of the second comparator, wherein the first comparator compares the first threshold voltage with the first back electromotive force, and the second comparator compares the second threshold voltage with the first back electromotive force, wherein the back electromotive force detecting circuit detects the first back electromotive force, and the brake control circuit judges a movement speed of the magnetic head based on comparison results of the first comparator and the second comparator when a first power supply to the magnetic disk storage apparatus is stopped, wherein if the first comparator determines that the first back electromotive force detected when the first power supply to the magnetic disk storage apparatus is stopped is greater than the first threshold voltage, the brake control circuit judges the movement speed being greater than the first preset speed and the brake control circuit brakes the second motor, wherein if the second comparator determines that the first back electromotive force detected when the first power supply to the magnetic disk storage apparatus is stopped is greater than the second threshold voltage, the brake control circuit determines the movement speed being greater than the second preset speed and the brake control circuit brakes the second motor, wherein the retract control circuit is adapted to drive the second motor to move the magnetic head to a retract position after the brake control circuit braking the second motor when the first power supply to the magnetic disk storage apparatus is stopped, wherein when a predetermined time elapses after the first power supply to the magnetic disk storage apparatus is stopped, the brake control circuit judges the movement speed of the magnetic head based on comparison results of the first comparator and the second comparator.