Patent ID: 7489467

Claim:
A method of measuring track widths in a hard disk drive, the method comprising: calculating a plurality of estimation values based on differences in intensity between a plurality first measurement signals produced in relation to a head of the hard disk drive based on a plurality of burst signals stored in servo sectors of a track when the head moves along the track on a first side of a center of the track, and a plurality of second measurement signals produced in relation to the head of the hard disk drive based on the plurality of burst signals when the head moves along the track on a second side of the center of the track opposite the first side; normalizing the plurality of estimation values; and, detecting excessive variation in the track widths of the hard disk drive based on the normalized estimation values, wherein the plurality of burst signals comprises first through fourth burst signals, and the plurality of first and second measurement signals produced in relation to the plurality of burst signals comprises respective first through fourth measurement signals corresponding to the first through fourth burst signals; and the calculating of the predetermined estimation values comprises: determining whether the track is an odd numbered track or an even numbered track, if the track is an odd numbered track, calculating a first value “Neg” as an absolute value of a difference between an intensity of the second measurement signal and an intensity of the fourth measurement signal, as read by the head when moving along the first side of the track, and calculating a second value “Pos” as an absolute value of a difference between an intensity of the first measurement signal and an intensity of the fourth measurement signal, as read by the head when moving along the second side of the track; and if the track is an even numbered track, calculating the first value “Neg” as an absolute value of a difference between an intensity of the first measurement signal and an intensity of the third measurement signal, as read by the head when moving along the first side of the track, and calculating the second value “Pos” as an absolute value of a difference between an intensity of the second measurement signal and an intensity of the third measurement signal, as read by the head when moving along the second side of the track, the first and second values being included within the plurality of estimation values.