Syquest Technology, Inc.

Ben Alaimo

Robert F Couse

Disclosed is a servo control apparatus for controlling a servo means that positions a recording head over a disk-shaped data storage medium. If the disk-shaped data storage medium is improperly mounted on a disk drive causing wobble of the disk as it turns, then the problem of runout occurs so that each of the tracks of data on the disk do not pass directly under the head throughout the whole rotation of the disk. The present invention provides a reference track near the outside circumference of the disk on which reference data is stored in a plurality of bursts spaced around the reference track. The servo control apparatus detects the reference data for each of the bursts and calculates the position of the centerline of the reference track with respect to the head for each of the bursts. From this calculation for 8 bursts spaced around the reference track, a computer means generates a runout factor which is used to control the servo means to position the head compensating for runout for each of the data tracks on the disk.

Servo control apparatus for a disk drive

Servo control apparatus including a recording head to read first and second servo data bytes stored across a track on opposite sides of a track centerline, a servo demodulator to count the first and second bytes and produce a resultant count representing any offset of the head relative to the centerline, a head positioner to move the head, and a microcomputer which controls the head positioner to position the head in response to the resultant count. The invention is implemented digitally, is simple and inherently compensates for expansion or contraction of the track to accurately center the head.

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Campbell, CA, United States of America

Ben Alaimo