Western Digital Technologies, Inc.

Masao Miyamura

Jie Yu

David D Nguyen

David Dung Tien Nguyen

Jinsheng Bill Jang

Teddy T C Chen

A method for detecting a servo address mark (SAM) of a servo sector of a disk of a disk drive during a servo field sync-up operation is disclosed. The method includes: detecting a start of a preamble; opening a SAM search window to detect the SAM; and continuing to detect the presence of the preamble during a SAM search time period. Further, the method discloses that: if the preamble is detected, the SAM search window is continued; and if the preamble is not detected, and the SAM is not detected, the SAM search window is closed.

Detecting a servo address mark (SAM) in a servo field sync-up operation

A disk drive comprising a moveable head, a disk, and a servo controller to control track following operations is disclosed. The disk includes a plurality of tracks in which a substantial majority of the tracks include a plurality of servo sectors utilized in track following operations. The servo controller implements a program during power-up to: calculate servo position correction values using a set of servo position correction coefficients that have been pre-selected for the disk drive based upon the class of disk drive in which the set of servo position correction coefficients have been coded into the program; store the servo position correction values in a pre-determined servo position correction look-up table in memory; and utilize the pre-determined servo bursts correction look-up table to track follow on a reserved track of the disk.

Providing pre-determined servo position correction values for use during disk drive initialization

A perpendicular media recording (PMR) servo track writer (STW) system and method for writing servo sectors onto a disk is disclosed. The servo writer includes a head positioner to position a head of a head disk assembly (HDA) relative to a disk, wherein the head writes servo sectors onto the disk with a perpendicular flux. The servo writer includes a controller to control the head positioner such that the head writes servo sectors onto the disk from one of an inner diameter (ID) or an outer diameter (OD) of the disk to a middle diameter (MD) of the disk, respectively, followed by writing servo sectors between the other of the OD or the ID of the disk to the MD of the disk, respectively.

System and method for writing servo sectors in a perpendicular media recording environment

A method is disclosed for improving servo performance in a disk drive having a plurality of concentric tracks. Each track has a plurality of first-type servo sectors and a plurality of second-type servo sectors. In the method, track identification information and track position information are read from a first-type servo sector. A track number and a transducer position are estimated for a second-type servo sector. Track position information is read from the immediately following second-type servo sector. An odd/even property from the second-type servo sector is compared with an odd/even property for the estimated track number. The odd/even property of the estimated track number is conditionally adjusted such that the odd/even property of the estimated track number matches the odd/even property from the second-type servo sector. A position error signal is determined using the adjusted track number and the track position information read from the second-type servo sector.

Method for improving servo performance in a disk drive having tracks with mini servo wedges

A method is disclosed for improving head position determination in a disk drive having a transducer head and a rotating disk with a plurality of embedded servo wedges for defining a plurality of concentric data tracks. Each servo wedge has a plurality of servo bursts for providing radial track position information. In the method, the servo bursts within a servo wedge are read and a burst amplitude is determined for each servo burst. The burst amplitudes are compared to determine a radial servo position zone. A fine radial head position within the radial servo position zone is determined based on a ratio having a numerator consisting of an algebraic sum and difference of the burst amplitudes and a denominator consisting of an algebraic difference between a largest burst amplitude and a smallest burst amplitude.

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Diamond Bar, CA, United States of America

Masao Miyamura