Dynamic magnetic information storage or retrieval – General recording or reproducing – Recording-or erasing-prevention
Reexamination Certificate
2007-06-05
2007-06-05
Wellington, Andrea (Department: 2627)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Recording-or erasing-prevention
C360S031000
Reexamination Certificate
active
10977678
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.
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Che Xiaodong
Hsiao Wen-Chien (David)
Luo Yansheng
Sui Xiaoyu
Bracewell & Giuliani LLP
Davidson Dan I
Hitachi Global Storage Technologies - Netherlands B.V.
Wellington Andrea
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