METHOD FOR ECCENTRIC CONTROL OF MAGNETIC DISC, RECORD MEDIUM WITH RECORDED DATA ON THIS METHOD, AND MAGNETIC DISC COMPRISING THIS METHOD

摘要

A method for eccentric control of the magnetic disc of a magnetic disc drive which enables the high−speed calculation of the manipulated variable of a magnetic head, the suppression of a deterioration in control performance due to a control delay with a long calculation time, and the realization of a stable control performance even when a variation in positional error of the magnetic head from a target position is large such as in the seek or settling of the magnetic head. Upon the start−up of the magnetic disc drive, a phase relation between the number of servo information recorded in the magnetic disc (15) and the eccentricity of the magnetic disc is learned. Upon the positioning of the magnetic head, a signal resulting from the multiplication of either of a sine wave or cosine wave with a correction of a phase delay amount according to the rotation frequency of the magnetic disc by a weighting coefficient is fed forward as an eccentric controlled variable to compensate for an eccentricity.