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:
Jan. 16, 2001
Filed:
Jul. 27, 1998
Isamu Tomita, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A magnetic disk drive capable of specifying even the type of a medium defect with a small number of read/write operations is disclosed. A read signal is sampled. A defect detector,of a read channel IC includes a (1+D) calculation circuit,for adding the current and preceding sample values or the absolute values thereof. The two types of sums of the current and preceding samples are compared with a lower reference value and an upper reference value preset in comparators,, respectively. A portion where the sum of the sample values exceeds the upper reference value is detected as a medium defect due to thermal asperity, a portion where the sum of the absolute values of the sample values is lower than the lower reference value is detected as a medium defect due to a missing, signal and a portion where the sum of the absolute values of the sample values exceeds the upper reference value as a medium effect due to an extra, signal thereby generating a defect detection signal DD. Three types of defects can thus be detected with a single read operation.