Head positioning control system for disk drives each formed by

Abstract

Disclosed is a head positioning control system for disk drives which enables fast access even when eccentricities of tracks defined with servo control information relative to the center of rotation are different among disks assembled after the servo control information is externally written on the respective disks. The head positioning control system is adapted to a disk drive comprising a plurality of disks each having a record surface on which servo control information indicating positions in a radial direction on a disk is recorded, and heads associated with the plurality of disk record surfaces and designed to detect information stored on the plurality of disk record surfaces. The servo control information includes position information in the radial direction on each disk record surface and defines servo-control circular trajectories. In addition to known components, the head positioning control system includes an eccentric information memory for storing eccentric information concerning eccentricities of servo-control circular trajectories on disk record surfaces relative to the center of rotation, and an optimal processing unit that when object disk record surfaces are changed according to an instructed target address, executes processing, which requires the shortest time for accessing a target address, on the basis of eccentric information.