Patent ID: 6972918
Filing Date: 2005-12-06
Classification: G11B

Abstract:
1. A magnetic disk system comprising: a first motor for revolving a magnetic disk; a magnetic head for reading information out of a memory track on the magnetic disk; a second motor for shifting the magnetic head over said disk; a second motor drive circuit including a transistor for controlling a current to be made to flow to the coil of the second motor, for shifting the magnetic head by controlling the gate voltage of said transistor in accordance with a current command value; a control circuit capable of generating a current command value for the second motor drive circuit in time of power supply interruption; and a booster circuit capable of boosting a voltage resulting from the rectification of a back electromotive force generated in the coil of said first motor, wherein said control circuit, in time of power supply interruption and in a state in which said transistor is turned off, detects the shifting speed of the head on the basis of a back electromotive force generated in the coil of said second motor, generates the current command value which is to serve as a speed target, and supplies the current command value to said second motor drive circuit, and wherein said second motor drive circuit operates on a voltage boosted by said booster circuit, and in time of power supply interruption controls the current flowing to the coil of said second motor in accordance with the current command value from said control circuit to shift said magnetic head to a prescribed standby position.