International Business Machines Corporation

Martin R Green

John Jeffrey Stephenson

Michael Charles Stich

Mark David Hagen

Randolph B Heineke

Todd Barry Anderson

Lawrence P Segar

William J Hunt

Mark E Bofferding

Joseph M Humel

In a disk storage device dedicated servo system, a reference track is written in the outer guardband of the servo surface and each of the data surfaces. Supplemental position error signal (PES) values are obtained from the difference of servo and data surface samples at a plurality of locations around the disk and stored for access during read/write operations. The supplemental PES values are combined with the dedicated surface PES values to yield a composite PES that more accurately follows the data track centerline of the disk surface being addressed. The supplemental PES values are also periodically updated. To provide a more accurate correction of the composite PES, two consecutive supplemental values are used and an interpolation is calculated to provide a continuously changing supplemental PES value for modification of each sector actuator drive pulse between the two current supplemental PES values. Provision is also made in the apparatus to make the correction technique tolerant of tangential skew that may make tracks unreadable because of early or late timing through the provision of sequences of alternative early and later sample sector sequences.

Disk drive servo control

A transducer head skew arrangement used in a multiple disk drive data storage system is provided. The disk drive unit includes a plurality of magnetic disk surfaces mounted for simultaneous rotation about an axis. A first sequence of servo information tracks are arrayed on a dedicated servo disk surface. At least one servo reference track is written on each data disk surface for storing servo reference information. The servo reference track is written on a first data disk surface aligned with a predefined servo information track on the dedicated servo disk surface. Then servo reference tracks are sequentially written on each successive consecutive data disk surface progressively offset radially from the last written servo reference track. A plurality of data information tracks for storing data are disposed at predetermined positions relative to the servo reference track on each the data disk surface. A servo transducer head is mounted for movement in a radial direction across the first dedicated servo information for reading servo information; and a plurality of data transducer heads are mounted for movement with the servo transducer head in a radial direction across the disk surfaces for reading the servo reference tracks and for reading and/or writing data to the data information tracks. The distance moved by transducer heads for a cylinder switch is the same distance moved for each head switch, so that track-to-track seek time is minimized without requiring any additional time delay for each head switch. An overall data transfer rate increases for every data transfer accessing more than one data cylinder.

Transducer head skew arrangement for disk drive system

Disclosed is a method for performing a seek operation in a disk drive using current in the saturation mode to accelerate and decelerate the actuator arm. In a first embodiment, several measurements are made during the acceleration portion of the seek to estimate the deceleration available in saturation mode. In a second embodiment, the point at which the current is switched from acceleration current to deceleration current is adjusted based upon the position where the actuator arm comes within a desired amount of the velocity of a velocity profile assuming worst case conditions.

Method and apparatus for performing a seek

Growing community of inventors

Rochester, MN, United States of America

Martin R Green