Determining repeatable runout cancellation information using PES information generated during self servo-writing operations
View Patent ↗Disclosed is a method for generating a repeatable runout (RRO) compensation value set for a circular track on a magnetic medium on a surface of a disk in a disk drive. The magnetic medium has a plurality of previously written spiral servo tracks for providing position information during a self servo-writing operation. In the method, servo burst patterns are written at a plurality of radial locations on the magnetic data storage surface during circular tracking operations using the spiral servo tracks, and respective position error signals generated during the circular tracking operations are stored. The servo burst patterns at the plurality of radial locations define a circular data track. The RRO compensation value set for the circular data track may be generated based on the respective stored position error signals generated during the circular tracking operations for writing the servo burst patterns at the plurality of radial locations.
1. A method for generating a repeatable runout (RRO) compensation value set for a circular data track on a magnetic medium on a surface of a disk in a disk drive, wherein the magnetic medium has a plurality of previously-written spiral servo tracks for providing position information during a circular tracking operation, the method comprising:
writing servo burst patterns at a first radial location on the magnetic data storage surface during a circular tracking operation using the spiral servo tracks, and storing first position error signals generated, using the spiral servo tracks, during the circular tracking operation for writing the servo burst patterns at the first radial location,
writing servo burst patterns at a second radial location on the magnetic data storage surface during a circular tracking operation using the spiral servo tracks, and storing second position error signals generated, using the spiral servo tracks, during the circular tracking operation for writing the servo burst patterns at the second radial location,
writing servo burst patterns at a third radial location on the magnetic data storage surface during a circular tracking operation using the spiral servo tracks, and storing third position error signals generated, using the spiral servo tracks, during the circular tracking operation for writing the servo burst patterns at the third radial location,
writing servo burst patterns at a fourth radial location on the magnetic data storage surface during a circular tracking operation using the spiral servo tracks, and storing fourth position error signals generated, using the spiral servo tracks, during the circular tracking operation for writing the servo burst patterns at the fourth radial location, and
generating the RRO compensation value set for a circular data track, defined by the servo burst patterns at the first, second, third and fourth radial locations, based on the stored first, second, third and fourth position error signals.
2. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 1 , further comprising using the RRO compensation value set during a track following operation along the circular data track.
3. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 1 , wherein the servo burst patterns at the first, second, third and fourth radial locations form a plurality of embedded servo sectors for providing position information during track following along the circular data track.
4. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 3 , further comprising:
track following along the circular data track using the RRO compensation value set and determining a position error signal for each servo sector of the circular data track; and
determining an improved RRO compensation value for each servo sector based on at least one position error signal determined while track following along the circular data track.
5. A method for generating a repeatable runout (RRO) compensation value set for a circular data track on a magnetic medium on a surface of a disk in a disk drive, wherein the magnetic medium has a plurality of previously-written spiral servo tracks for providing position information during a circular tracking operation, the method comprising:
writing servo burst patterns at a plurality of radial locations on the magnetic data storage surface during circular tracking operations using the spiral servo tracks, and storing respective position error signals generated, using the spiral servo tracks, during the circular tracking operations for writing the servo burst patterns at the plurality of radial locations, wherein the servo burst patterns at the plurality of radial locations define the circular data track; and
generating the RRO compensation value set for the circular data track based on the respective stored position error signals generated during the circular tracking operations for writing the servo burst patterns at the plurality of radial locations.
6. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 5 , further comprising using the RRO compensation value set during a track following operation along the circular data track.
7. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 5 , wherein the servo burst patterns at the plurality of radial locations form a plurality of embedded servo sectors for providing position information during track following along the circular data track.
8. A method for generating a repeatable runout (RRO) compensation value set as defined in claim 7 , further comprising:
track following along the circular data track using the RRO compensation value set and determining a position error signal for each servo sector of the circular data track; and
determining an improved RRO compensation value for each servo sector based on at least one position error signal determined while track following along the circular data track.