Patent ID: 6826007
Filing Date: 2004-11-30
Classification: G11B

Abstract:
A disk drive comprising:(a) a disk comprising a plurality of tracks; (b) an actuator arm; (c) a head connected to a distal end of the actuator arm; (d) a voice coil motor comprising a voice coil, the voice coil motor for rotating the actuator arm about a pivot to actuate the head radially over the disk; and (e) a velocity extraction circuit for extracting a velocity of the actuator arm from a back EMF voltage across the voice coil, the velocity extraction circuit comprising an integrator for integrating a first voltage representing a current flowing through the voice coil during a first time interval to generate a first integration and for integrating a second voltage across the voice coil during a second time interval to generate a second integration, wherein: a polarity of the first voltage is opposite a polarity of the second voltage; and the velocity of the actuator arm is computed by summing the first and second integrations.