Patent ID: 7893643
Filing Date: 2011-02-22
Classification: G11B

Abstract:
1. A method for reducing jitter associated with a disk drive motor assembly wherein the disk drive motor assembly includes a rotor having a plurality of pair poles and a stator, the method comprising: detecting, for a single rotation of the rotor, a plurality of zero cross signals; determining rotation data for each of the detected plurality of zero cross signals; collecting a set of rotation data over a plurality of rotations for each of the detected plurality of zero cross signals; averaging separately each set of rotation data for each of the detected plurality of zero cross signals forming a plurality of set averages; averaging the plurality of set averages creating an overall average; ascertaining pair pole asymmetry for each zero cross signal by comparing the plurality of set averages to the overall average; and reducing jitter by removing pair pole asymmetry from each of the plurality of zero cross signals.