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Adaptive Stress to Map a Defect

IP.com Disclosure Number: IPCOM000015771D
Original Publication Date: 2002-Mar-14
Included in the Prior Art Database: 2003-Jun-21

Publishing Venue

IBM

Abstract

Disclosed is a method to map a defect properly in Hard Disk Drive (HDD) when manufacturing. To detect a defect on a disk efficiently in short time, it is used a special read operation with some stresses. These stresses are data pattern frequency (without a randomizer), restricted ECC, disabled amplitude gain control, restricted decoding and so on. As a result, a repeated error sector is mapped as a defect. However there is different sensitivity to the stress between reading heads. Then that makes different defect detectability by the heads. Therefore it is able to minimize defect escape and too much detection by adapting those stresses to each head characteristic. Because the adaptive stress can uniform the defect detectability. For each head, 1. Measure head amplitude using the fastest cyclic pattern and the slowest cyclic pattern.