SERVO CONTROL SYSTEM USING SERVO PATTERN TIME OF FLIGHT FOR READ/WRITE HEAD POSITIONING IN A MAGNETIC RECORDING SYSTEM

摘要

Abstract of the DisclosureAn improved servo control system for data trackfollowing of the read/write head in a magnetic recordingsystem uses a pattern of segments of servo informationslanted across the data tracks. The time of flight ofthe servo segment from occurrence of a reference pulseuntil the peak servo signal is read by the head is anindication of the position of the head in a directionperpendicular to the desired track. This time is comparedwith the known time of flight if the head were preciselyover the centerline of the desired track and the timedifference is used to generate a control signal toposition the head over the track centerline. In anembodiment where each segment is slanted across only onetrack, the reference pulse is the beginning of the servosignal and the time measurement is the number of fixedfrequency magnetic transitions read by the head in theservo segment. When the system is used in flexible diskdrives, the servo segments are written in one of the datasectors on the flexible disk by the user's disk drive.