Hitachi Global Storage Technologies Netherlands B.v.

Maxtor Corporation

Adrian E Cerda

Amir Hossein Chaghajerdi

Bryan Rowan

Pushkar Hingwe

Yu Sun

Lloyd E Levy

Jingbo Yu

Pang L Tan

A magnetic recording disk drive has compensation for both mechanical disturbances and electrical disturbances. The disk drive's servo control system includes mechanical disturbance (MD) feedforward compensation and electrical disturbance (ED) feedforward compensation, of which either or both can be selectively enabled and disabled. In the operation of the disk drive, it is first determined that there is some disturbance that is causing track misregistration (TMR). The system is then tested to determine if the ED is greater than an ED threshold by measuring an averaged ED sensor signal. If ED is greater than the ED threshold, the system is then tested for a reduction in TMR by selectively turning MD compensation and ED compensation on and off, and determining changes in the position error signal (PES). Depending on the test results from the PES measurements, one or both of MD compensation and ED compensation is left on, and maintained on until the TMR falls below the predetermined threshold.

Magnetic recording disk drive with switchable compensation for mechanical and electrical disturbances

A method for compensating for a disturbance in power from a power supply, wherein the disturbance without the compensating would otherwise affect a positioning apparatus coupled to the power supply. The method comprises receiving the disturbance in power from the power supply, deriving a compensation for the disturbance in the power, and transmitting the compensation to a control system for the positioning apparatus.

Power disturbance compensation

A method and apparatus for providing a temporary utility zone in a disk drive. A disk surface has a write head associated therewith. The write head is used to write spiral servo information and a propagation state indicator onto the disk surface. The spiral servo information and propagation state indicator are used to perform a self-servo write operation on the disk surface.

Method and apparatus for performing a spiral self-servo write operation in a disk drive using an auto detection scheme

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San Jose, CA, United States of America

Adrian E Cerda