Identification and cancellation of cage frequency in a hard disc drive
US6785073B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 2001 |
| Grant date | Aug 31, 2004 |
| Priority date | — |
| Expiry date | Feb 17, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/5582
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Written-in runout due to vibration of the cage of a spindle motor of a disc drive is detected by identifying an initial cage frequency value of the motor. A written-in magnitude of successive servo burst closures, D(nc), is read over a plurality of tracks, and a maximum servo burst closure D(ncp) is identified from the plurality of read servo bursts. A magnitude of the cage frequency at a servo sector n0 is calculated based on a difference between the read magnitudes of the servo burst closures at servo sectors nc and nc+1, and a phase of the cage frequency is calculated based on the magnitude of the written-in cage frequency at servo sector n0. The profile, in the form of cage frequency, maximum servo burst closure magnitude, and initial phase, is stored in a memory or table for each of a plurality of radial zones of tracks. The profile is combined with a position error signal and applied to the controller in a feed forward scheme to adjust the position of the head based on the written-in runout.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.