FEED-FORWARD COMPENSATION OF CAGE FREQUENCY USING A REFERENCE HEAD IN A SERVO-WRITER

摘要

-34- FEED-FORWARD COMPENSATION OF CAGE FREQUENCY USING A REFERENCE HEAD IN A SERVO-WRITER Abstract of the Disclosure A system, modules, means, and computer readable media for and a method ofcompensating disturbances that cause track shape irregularities on a disc in a disc driveduring a disc servo-writing process performed by a servo-writer are disclosed. Thedisturbances substantially attributable to a nonrepeatable runout (NRRO) are present duringthe servo-writing process. A substantial component of the NRRO is a cage frequencygenerated by a spindle motor mechanism in the disc drive. A reference cage frequency isdetermined during a servo-writing process by using a position sensor. Then a feed-forwardinput signal is determined based at least on the reference cage frequency during the servo-writing process. In addition, the feed-forward input signal is feed-forwardly transmitted tothe servo-writer. In the servo-writer, the feed-forward input signal is utilized to substantiallyreject disturbances that cause the track shape irregularities while the servo-writing headelectrically connected to the servo-writer is writing servo patterns on a user track during theservo-writing process.Figure 8