Magnetic recording drive dynamics during seeking and parking

A novel magnetic characterization technique has been developed to monitor head-disk spacings at high bandwidths during seeking, parking and during operational vibration and shock. This technique relies upon measurements of the magnetic amplitude of a constant frequency pattern written on every second track and on the readout of the graycode and servo bursts during seeking or parking. Magnetic data obtained during the crossing of thousands of magnetic tracks is analyzed with two subsequent envelope calculations. With well designed inductive and magnetoresistive head drives in normal seeking modes, head-disk spacing variations are within ±5 nm. Large head-disk spacing fluctuations are detected when using hard crash stops and parking at velocities in excess of 0.5 m/sec