Patent ID: 7102846
Filing Date: 2006-09-05
Classification: G11B

Abstract:
1. A magnetic tape drive for reading and/or writing data with respect to a magnetic tape media, said magnetic tape media having prerecorded servo information in a plurality of separate servo bands comprising at least one pattern of detectable transitions positioned longitudinally along a magnetic tape media, at least one of which detectable transitions is non-parallel to another detectable transition in said pattern, said patterns comprising at least one gap between said non-parallel detectable transitions; and said separate servo bands positioned laterally across said magnetic tape media, at least one of said patterns of a separate said servo band having variations in said gap of said pattern with respect to at least one of said patterns of another of said separate servo bands; comprising: a magnetic tape head and read and/or write channel for reading and/or writing data on said magnetic tape media; a drive mechanism for moving said magnetic tape media longitudinally with respect to said magnetic tape head; an actuator for positioning said magnetic tape head laterally with respect to said magnetic tape media; at least one servo transducer narrower than the lateral width of said separate servo bands, for sensing said detectable transitions from at least one of said plurality of separate servo bands; a servo detector for detecting the timing of said detectable transitions as sensed by said at least one servo transducer to determine the lateral track position of said at least one servo transducer with respect to said lateral width of said separate servo bands; a decoder for determining, from said detected timing of said detectable transitions, said variations in said gap of said pattern with respect to at least one of said patterns of another of said separate servo bands, and determining from said determination of variations, which of said at least one of said separate servo bands is being sensed by said at least one servo transducer; and a servo control for operating said actuator to position said magnetic tape head laterally with respect to said magnetic tape media in accordance with said detection of said servo detector and said servo band determination of said decoder; wherein said detectable transitions of a pattern are written in a first burst of at least one of said detectable transitions in a first azimuthal orientation, a second burst of at least one of said detectable transitions in a second azimuthal orientation, a third burst of at least one of said detectable transitions in said first azimuthal orientation, and a fourth burst of at least one of said detectable transitions in said second azimuthal orientation, and first gaps separating said first and said second bursts and separating said third and said fourth bursts, and second gaps separating said second and said third bursts and separating a sequentially adjacent said pattern; and wherein said variations in said gap of said patterns of said separate servo bands comprises an expanded one of a set of said first gaps and/or a set of said second gaps and narrowed one of a set of said first gaps and/or a set of said second gaps; and wherein said servo detector detects said timing to determine the lateral track position of said at least one servo transducer from said detectable transitions of said first and said second said bursts, and from said detectable transitions of said first and said third said bursts; and wherein said decoder determines which of said at least one of said separate servo bands is being sensed by said at least one servo transducer, from said variations in said sets of first gaps and/or said sets of second gaps of said pattern with respect to at least one of said patterns of another of said separate servo bands.