The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 24, 2001
Filed:
May. 18, 1999
Donald Ray Gillis, San Jose, CA (US);
Richard Mark Kroeker, Morgan Hill, CA (US);
Mike Suk, Milpitas, CA (US);
Reinhard Ferdinand Wolter, Saratoga, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and apparatus for monitoring the quality of the readback signal of data written on a magnetic recording disk in a disk drive and for limiting data loss due to physical damage at a slider/disk interface. The amplitude of a read signal is continuously monitored in the read channel, either by directly measuring the read signal amplitude or by monitoring the amplification level of the automatic gain control (AGC) circuit in the read channel which is inversely proportional to the read signal amplitude. If the amplitude of the monitored read signal decreases below a chosen level, the location of the data on the disk track is flagged as possibly damaged. The data is rewritten at the same location and then reread to see if full recovery of the degraded data is possible. If the amplitude read signal of the rewritten data is greater than a chosen level, the disk track is judged to be usable and normal operation continues. If the amplitude of the rewritten data read signal is less than the chosen level, permanent damage of the location on the data track is assumed and the data is rewritten at a new location on the magnetic recording disk.