System, method, and apparatus for in-situ stray magnetic field measurement
US7227711B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 2004 |
| Grant date | Jun 5, 2007 |
| Priority date | — |
| Expiry date | Aug 30, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B33/1493
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A hard disk drive (HDD) detects and measures external stray magnetic fields with existing HDD components. After detecting a strong external magnetic field, read and write operations of the HDD are suspended, and/or other proper corrective actions are taken to minimize loss of data. To measure the stray magnetic field, the magnetic head reader is used as a field sensor. The resistance of the reader changes in the presence of the field, such as with the preamp in the HDD. The resistance also changes with temperature. If the temperature inside the HDD is measured, the resistance change due to temperature is normalized. Even without being able to measure the HDD temperature, the stray magnetic field can be measured with a top head and a bottom head in the HDD. The temperature sensitivity of the reader is thereby cancelled out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.