Method of self-testing magneto-resistive heads for instability in a disk drive
US6373647B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1999 |
| Grant date | Apr 16, 2002 |
| Priority date | — |
| Expiry date | Nov 12, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2005/0008
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An MR head self-testing method is provided to test for instability in MR heads incorporated with a hard disk drive. A first method is carried out with the disk rotating and includes positioning the MR head over a rotating magnetic storage disk and controlling the MR head to read from erased data fields defined on the disk. This read signal is filtered and conditioned according to preprogrammed filter coefficients contained in an FIR filter to provide an exaggerated read error signal. The exaggerated read error signal is provided to a digital comparator and counter circuit for detecting and counting voltage baseline jumps that exceed preprogrammed positive and/or negative threshold values. The counted positive and negative voltage baseline jumps, which are indicative of MR head instability, are provided to an error diagnostic register for analysis. If the error diagnostic register contains single polarity voltage baseline jumps, the voltage baseline jumps may be caused by thermal asperities on the disk. If the error diagnostic register contains both positive and negative voltage baseline jumps, the voltage baseline jumps may be caused by MR head instability. A second method is carri…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.