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:
Dec. 28, 1999
Filed:
Sep. 30, 1997
Seagate Technology, Inc., , US;
Abstract
A method and apparatus for detecting and measuring head-disc interference, in a disc drive, for the purpose of taking preventative and corrective measures, to prevent disastrous head crashes and permanent data loss, is disclosed. The method and apparatus detect and measure the frequency modulation (FM) of a read back signal generated by longitudinal head oscillation, as a result of head-disc interference. The longitudinal head oscillation can be ascribed to the non-linear response of the air bearing supporting the head on the disk surface. The response exhibits a vibration frequency in the head in the 100 to 250 kHz range. The more severe the interference contact is, the higher the vibration amplitude which then leads to read signal frequency modulation (FM). A method and apparatus is described to detect the FM modulation and thereby to detect the severity of the head disk interference for proximity recording. A pre-written pattern on the disk can be read back to monitor for FM, and a modulation index, .beta., is generated by observing the resulting signal. By demodulating the modulated read back signal, the severity of the interference can be determined. This method can be applied as a diagnostic tool at a manufacturing test station, in a laboratory test setup, or in a disk drive using the disk drive's own read/write channel electronics, without the need for an external sensor.