Western Digital Technologies, Inc.

Western Digital Corporation

Terry C Dawson

Robert P Ryan

Ashok K Desai

Raffi Codilian

Jenghung Chen

John R Agness

Hemant Melkote

Steven Nemshick

Carl R Messenger

A disk drive is disclosed including a disk having a plurality of tracks, wherein each track comprises a plurality of embedded servo sectors. A head connected to a distal end of an actuator arm is rotated about a pivot by a voice coil motor (VCM) in order to actuate the head radially over the disk. The actuator arm is unloaded onto a ramp by seeking the head to a track near an outer diameter of the disk in response to the embedded servo sectors, switching to a velocity control mode to unload the actuator arm onto the ramp at a controlled unload velocity in response to a back electromotive force voltage generated by the VCM, and ramping a velocity command so that the velocity of the actuator arm when contacting the ramp is less than half the maximum unload velocity while traveling along the ramp.

Disk drive seeking to OD track and then ramping velocity to implement fast unload

A disk drive is discloses comprising a disk, a head connected to a distal end of an actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot in order to actuate the head radially over the disk. If when a power failure occurs the radial location of the head is less than a predetermined distance from the outer diameter of the disk, the VCM is controlled to move the head toward the inner diameter of the disk and stopping the head before it reaches the inner diameter of the disk. The VCM is then controlled to move the head toward the outer diameter of the disk until the actuator arm unloads onto a ramp.

Disk drive employing momentum based unload during power failure

A disk drive employs a method of operating a spindle motor to respond to a spin-down command to reduce the time required for subsequently responding to a spin-up command. After receiving the spin-down command, and while the rotor continues to spin in the forward-spin direction, a state machine is set to and maintained in a first predetermined register state such that a controlled rotor-stopping operation is performed. At the end of the controlled rotor-stopping operation, the rotor angle is within the range of a peaked forward direction waveform for a second predetermined register state of the state machine.

Disk drive employing method of spinning down its spindle motor to reduce the time required for subsequently spinning it up

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San Diego, CA, United States of America

Terry C Dawson