METHOD FOR RETRYING OFF-TRACK READ TO DATA OFF-TRACK WRITE, PARTICULARLY FOR READING DATA OFF-TRACK WRITTEN IN PROCESS THAT HEAD IS SHAKEN RIGHT AND LEFT BY UNSTABLE SETTLING OR INSTANTANEOUS SHOCK

摘要

PURPOSE: A method for retrying off-track read to data off-track write, particularly for reading data written off-track in a process that head is shaken right and left by unstable settling or an instantaneous shock is provided to read data written off-track by controlling a head so as to proceed with the locus of a sine wave shape in direction of a track center line. CONSTITUTION: A head is on a track having data written off-track(100). The data are read while the head becomes off from the track as much as the maximum track amount in one direction from a servo sector prior to two sectors from a data sector having an error(102), and the head becomes off from the track as much as the maximum track amount in direction opposite to the one direction from a servo sector immediately before the data sector having the error(104). If an read error is generated, the data are read while the head becomes off from the track as much as the maximum track amount in direction opposite to the one direction from the servo sector prior to two sectors from the data sector having the error(106-108), and the head becomes off from the track as much as the maximum track amount in the one direction from the servo sector immediately before the data sector having the error(110).