Seagate Technology Incorporated

Khalil B Dizaji

Reed David Hanson

Hai Thanh Ho

Michael Edward Baum

Brent Jay Harmer

Christopher Thomas Settje

Rodney Brittner

Joseph Wach

Jianbo He

The present invention reduces the time required for coefficient convergence and thus improves time-to-ready. To that end, the present invention provides an initial learn&#x2014;preferably non-zero&#x2014;coefficient. The initial learn coefficient is based on a translation of timing information to position information. One aspect of the present invention uses address marks of a disc then translates them to phase position information. The present invention measures the times between address marks of adjacent servo sectors. Variations between those times is related is related to disc runout, particularly disc eccentricity. Also, the servo sectors are used to identify at which phase the maximum amplitude (or magnitude) of the timing variations occur. This phase information and maximum amplitude are used as variables in determining the initial learn coefficient. The present invention also utilizes a plant model to predetermine a variable. This variable is used in conjunction with the phase and maximum amplitude variables to determine the initial learn coefficient. Other aspects of the present invention use approximations or statistical values to determine the initial learn coefficient. For example, the maximum amplitude can be based on a clearance between an inner diameter of a disc and a spindle. The phase can be based on a value within a range of phases. The plant model can be changed to include assumptions, approximations or other factors.

Initial learn of adaptive feedforward coefficients

A disc drive has transducers supported by an actuator to fly proximate data tracks on surfaces of rotating information storage discs. Each of the discs is partitioned into concentric regions. A control system arranges the deposition of data in write operations to the tracks on the disc surfaces, as data is written to the discs, such that the data is sequentially organized both on the tracks and within each of the regions. The control system writes data from a track adjacent a first region boundary in a first direction to a second region boundary until all tracks in a region are full. The control system executes a head switch between adjacent surfaces of the discs. The write sequence is repeated in each adjacent region until all regions are full. The resulting trapezoidal serpentine pattern of actuator movement and head switches is repeated until all of the write operations are complete.

Apparatus and method for writing data to an information storage disc

Method and apparatus for more accurate track following. Control circuitry rotates a data storage surface containing thousands of annular tracks. A 'measured' subset of the tracks is selected so as to be interspersed with an 'unmeasured' subset. The calibration profile is derived based on position error signals each obtained by reading from the measured subset and not from the unmeasured subset. Data from the unmeasured subset of tracks is ignored, in generating and/or updating the profile.

Efficient feedforward compensation for repeatable runout in a disc drive

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Louisville, CO, United States of America

Khalil B Dizaji