Maxtor Corporation

Toan Q Doan

Hai Thanh Ho

Bruce A Liikanen

The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW_RRO) values for each sector of each track at the drive level. The STW_RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW_RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Disk drive with compensation values calculated using a non-causal impulse response

The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW.sub.-- RRO) values for each sector of each track at the drive level. The STW.sub.-- RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW.sub.-- RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Efficient drive-level estimation of written-in servo position error

A servo sector allocation scheme for a disk based data storage system is disclosed that realizes an increased servo sampling rate without an associated increase in overhead. The scheme involves increasing the number of servo sectors on a subset (preferable one) of the disk surfaces in the disk drive while reducing the number on all remaining disk surfaces. A master servo feedback signal is then derived from the highly populated surface(s) and a slave servo feedback signal is derived from the surface that is being accessed. The master and slave servo feedback signals are then combined to form a single position error signal that is used to control the positioning of an appropriate transducer.

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West Lafayette, CO, United States of America

Toan Q Doan