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:
Nov. 25, 1997
Filed:
Oct. 10, 1995
John J Kardash, Gilroy, CA (US);
Quantum Corporation, Milpitas, CA (US);
Abstract
A hysteresis circuit for providing hysteresis for a degree of noise immunity when detecting zero-crossings of a hard disk drive. A comparator is used to detect the zero-crossings associated with one of the windings of the disk drive's spindle motor. When a zero-crossing is detected, the hysteresis circuit introduces a hysteresis voltage to one of the inputs to the comparator. A positive hysteresis voltage is applied when the slope of the back emf signal corresponding to the motor winding is negative. Conversely, a negative hysteresis voltage is applied when the back emf signal has a positive slope. The slope of the back emf signal is determined by a logic combination of the commutation signals used to commutate the spindle motor.