Patent ID: 7274529
Filing Date: 2007-09-25
Classification: G11B

Abstract:
1. A data recording disk drive comprising a data disk having a plurality of data tracks; a multiphase spindle motor having a winding for each phase and connected to the disk for rotating the disk; a transducer for writing data to or reading data from the data tracks on the disk; a carrier supporting the transducer; a ramp for holding the carrier off the disk when the disk drive is not operating; a voice coil motor (VCM) actuator that generates a back electromotive force (EMF) voltage when it is moving, the actuator connected to the carrier for moving the carrier generally radially across the disk in a track seek from one data track to another data track and for moving the carrier to the ramp; a dynamic braking circuit coupled to the actuator for braking the actuator only when the VCM back EMF voltage is less than a predetermined threshold when power to the spindle motor is removed; an adaptive brake controller coupled to the actuator for braking the actuator only when the VCM back EMF voltage is greater than said threshold when power to the spindle motor is removed, the adaptive brake controller being responsive to the length of the track seek at the time of spindle motor power removal; and a rectifier circuit for converting back electromotive force from the spindle motor to current for the actuator to retract the carrier to the ramp when power to the spindle motor is removed and after the actuator has been dynamically or adaptively braked.