Twin track vertical magnetic recording servo control method and apparatus with offset voltage compensation

摘要

This invention utilizes a sectored servo control having dual servo tracks recorded in the servo sector. In addition, the servo sector track portions have been recorded with two 180 DEG flux reversals in each track's polarity. The tracks are generally recorded with DC recording current to set a uniform magnetic polarity. The current is switched twice, i.e., from positive and negative and back again or vice versa for each servo track within the servo sector interval. This permits separation of the sensor, amplifier and servo signal offset voltages from the main servo signal itself. Two samples of the servo control voltage are taken during the servo sector interval and the polarity reversal of the servo track is necessary to allow separation of the offset voltages from a variety of sources from the off track or servo error signal.