Disk level servo write
AssigneeMobile Storage Technology Inc.
InventorsNoureddine Kermiche, Bruce D. Emo, John P. Squires
Life of this patent
Estimating the term…
Abstract
A method for assembling and operating a fixed media hard disk drive using a disk or a stack of disks on which servo information is pre-written off the drive spindle. The disks are subsequently mounted on the drive spindle and a set of rotationally concentric “virtual tracks” for seeking and following in terms of said pre-written servo tracks are defined. The use of the concentric virtual tracks assures minimal actuator motion during drive operation and increases acceptable offtrack tolerances. The off-spindle, pre-writing of the servo information increases the efficiency of the assembly operation and reduces the clean room burden.
Claims6
A method for assembling and operating a fixed media hard disk drive using disks on which servo information is pre-written while off the drive spindle of said hard disk drive, which disks are subsequently mounted on said drive spindle and on which are then defined a set of rotationally concentric “virtual tracks” for seeking and following in terms of said pre-written servo tracks comprising:
- providing a fixed media hard disk;
- mounting said disk in a servo track writing assembly dedicated to the writing of servo tracks;
- writing said servo tracks on said disk;
- transferring said servo-written disk to a disk drive assembly comprising a spindle, a read/write head, a head actuator assembly, and a runout compensator;
- mounting said disk on said spindle of said drive assembly;
- closing said disk drive assembly and mounting it on a PCB;
- testing said disk drive assembly;
- defining, during said testing process, a set of virtual tracks on said disk in terms of intersections between said pre-written servo tracks and circular paths of said read/write head, said intersections being obtained by means of a process comprising:
- choosing a set of n different radial positions on said disk;
- locking onto the written servo track at one of said radial positions;
- turning on the runout compensator;
- obtaining a position error signal with runout compensation included as a sum of harmonics multiplied by harmonic coefficients k1 and k2;
- choosing a transition rate, ε, to provide a smooth and stable transition from the physical track domain to the virtual track domain;
- recording harmonic coefficients k1 and k2;
- defining the position error signal for the virtual track in the virtual track domain;
- repeating the previous six steps for each of the remaining radial positions;
- creating a table in which all other virtual tracks are defined;
- storing said table as a non-volatile memory array;
- transitioning the disk drive to the virtual domain.
A fixed media hard disk drive using disks on which servo information has been pre-written off the drive spindle and on which virtual tracks are defined, comprising:
- a drive spindle;
- a read/write head;
- a head actuator assembly;
- a runout compensator
- a disk mounted on said drive spindle on which has been pre-written a set of servo tracks and on which is now defined a set of rotationally concentric “virtual tracks;”
- an array stored in non-volatile flash memory defining said “virtual tracks” in terms of said pre-written physical servo tracks, said virtual tracks being circular tracks defined by an array of intersections of said read/write head with servo positions on said pre-written tracks and said array of intersections being obtained by an analysis of the harmonic runout components of the pre-written servo tracks using said runout compensator;
- a printed circuit board on which the drive assembly is mounted.
Dependencies are inferred from the claim text.