Patent ID: 6574068
Filing Date: 2003-06-03
Classification: G11B

Abstract:
In a disc drive which uses a transducing head to store and retrieve data to and from a plurality of concentric tracks defined on a rotatable disc surface, a method for positioning the head adjacent a selected track, comprising steps of:(a) providing the disc surface with first, second, third and fourth radially staggered burst patterns each having a burst width, wherein the first and second burst patterns are arranged such that the edges from each of the first and second burst patterns are substantially collinear to form a first null, wherein the third and fourth burst patterns are arranged such that the edges from each of the third and fourth burst patterns substantially collinear to form a second null, and wherein the third and fourth burst patterns are radially offset from the first and second bursts by one half of a burst width; (b) defining a first combined burst signal PS1 as a difference between a magnitude of a burst signal transduced from the first burst pattern and a magnitude of a burst signal transduced from-the second burst pattern; (c) defining a second combined burst signal PS2 as a difference between a magnitude of a burst signal transduced from the third burst pattern and a magnitude of a burst signal transduced from the fourth burst pattern; (d) combining respective at least third order polynomial functions of PS1 and PS2 to provide a continuous position error signal with substantially linear slope between the first and second nulls; and (e) applying current to a motor coupled to the head to position the head in relation to a magnitude of the position error signal.