Proximity detection method for magnetic head and recording medium

Abstract

Touchdown is detected between an R/W head and disk by determining the variance in the frequency domain of a baseline position error signal (PES) and a PES measured after incrementally increasing the DFH control signal. To quantify the variance in the frequency domain, a discrete Fourier transform of the baseline PES and of each PES produced for a given DFH control signal is used. A band-limited PES variance is used to improve touchdown detection, but is not a requirement of this method.

1 . A method for determining a touchdown dynamic fly height (DFH) power setting for a read/write head, comprising:
 detecting touchdown using a plurality of different methods;   for each of the different methods, recording a DFH power setting when touchdown is detected; and   selecting a DFH power setting that is the lowest of the recorded DFH power settings as the touchdown DFH power setting.   
     
     
         2 . The method according to  claim 1 , wherein, in one of the different methods, touchdown is detected based on variances in position error signals in the frequency domain.