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:
Sep. 20, 2011
Filed:
Mar. 24, 2009
Hiroto Kikuchi, Nagano, JP;
Hiroto Kikuchi, Nagano, JP;
Fuji Electric Device Technology Co., Ltd, Tokyo, JP;
Abstract
A defect inspection method and device for a perpendicular magnetic recording medium that has discrete recording tracks and grooves between recording tracks, including DC demagnetizing the perpendicular magnetic recording medium, detecting a reproduced signal from the perpendicular magnetic recording medium after the DC demagnetizing, removing output fluctuation components caused by the grooves from the reproduced signal using a filter with a prescribed cutoff frequency and separating a peak output of the reproduced signal, comparing the peak output with a prescribed reference signal, and identifying a location where the peak output exceeds the reference signal as a defect location. The method further includes performing an envelope-detection on the reproduced signal, detecting a pre-format region in the perpendicular magnetic recording medium using the envelope-detection result, masking the detected pre-format region, and detecting the defect location in a region outside the masked pre-format region in the perpendicular magnetic recording medium.