Patent ID: 7292401
Filing Date: 2007-11-06
Classification: G11B

Abstract:
1. A head-disk tester for determining head-disk contact (HDC) comprising: a rotatable magnetic recording disk having no recorded magnetic transitions; an air-bearing slider maintained near the surface of the disk when the disk is rotating; a magnetoresistive (MR) read head on the slider, the MR read head providing, at a frequency less than about 3 MHz, an MR signal having a first amplitude with HDC and a second amplitude without HDC; a fly-height actuator for changing the spacing between the read head and the disk surface; a filter for detecting the amplitude of the MR signal from the read head at a frequency less than about 3 MHz; and a Schmitt trigger connected to the output of the filter for providing a high output when the filter output is above a threshold, said threshold representing said second MR signal amplitude plus a predetermined percentage of the difference between said first and second MR signal amplitudes.