Patent ID: 6021013
Filing Date: 2000-02-01
Classification: G11B

Abstract:
A servo control system for positioning a magnetic head adjacent a surface of a moving magnetic storage medium for reading a servo pattern recorded in at least one track on the storage medium surface, the system comprising:a head assembly having at least one servo read head for reading the servo pattern on the storage medium in a transducing direction and generating a read head signal representative of the servo pattern;a servo decoder that receives the read head signal and decodes it to generate a position signal that indicates the position of the read head relative to the servo pattern;a translation assembly that is activated to position the head assembly relative to the storage medium;a servo controller that activates the translation assembly in accordance with the position signal, wherein:the servo decoder including means for generating a substantially speed invariant position signal that is based on a ratio of time intervals between a plurality of predetermined pairs of magnetic flux transitions in the servo pattern, and means for detecting errors in the substantially speed invariant position signal by means of pattern recognition of the read head signal, such that the servo decoder correlates the read head signal with predetermined patterns recorded on the storage medium and, if the signal does not correlate within an error limit, then the servo decoder indicates an error condition.