Patent ID: 8310780
Filing Date: 2012-11-13
Classification: G11B

Abstract:
1. A method, comprising: providing a servo write head having a first write gap and a second write gap spaced apart and an induction coil configured to generate respective magnetic fields proximate to said first and said second write gaps when a current is applied to said coil by a bipolar servo write driver, said bipolar servo write driver configured to generate both negative and positive polarity currents; generating a varying current signal using said bipolar servo write driver; moving a magnetic storage medium past said first and said second gaps in a direction from said first write gap toward said second write gap; said varying current signal includes a non-write phase, a preamble phase, a servo mark write phase and a closing phase; said varying current at an initial current level during said non-write phase; said preamble phase comprising an abrupt change in current from said initial current level to a first current level and a first current ramp from said first current level to a second current level; said servo mark write phase comprising current pulses between third and fourth current levels to write servo marks; said closing phase comprising a second current ramp from said second current level to said first current level and an abrupt change in current from said first current level to said initial current level; and wherein servo marks are written only during said servo mark write phase.