Patent ID: 7483234
Filing Date: 2009-01-27
Classification: G11B

Abstract:
1. A control device of a storage apparatus having a head which is provided with a reading element and a recording element, is provided with a heater which varies a protrusion value by thermal expansion caused by electric power distribution and heating, and accesses data by flying over a rotating recording medium, the control device comprising a write clearance control unit which performs write heat upon recording by electric power distribution to the heater according to a predetermined base heater control value; a read clearance control unit which performs read heat upon reproduction by electric power distribution to the heater according to a control value which is obtained by adding the predetermined base heater control value to an adjustment heater control value; an amplitude measurement unit which repeats, upon desired correction, a process of attaining a write heat state by the write clearance control unit in the state in which the head is positioned to an arbitrary measurement track so as to perform recording in a data region of the measurement track, then switching the state to a read heat state by the read clearance control unit so as to reproduce a predetermined region of the measurement track, and detecting an amplitude of a read signal; a variance calculation unit which calculates a variance from a plurality of amplitude measurement values measured by the amplitude measurement unit; a contact determination unit which performs recording in a data region of the measurement track while sequentially increasing the base heater control value by the write clearance control unit when the variance is less than a threshold value, then performs reproduction of a predetermined region of the measurement track by switching the state to the read heat state by the read clearance control unit, repeats a measurement process by the amplitude measurement unit which detects the amplitude of the read signal, and determines that the head is in contact with the medium when the variance exceeds the threshold value; and a write clearance calculation unit which calculates a clearance of the head upon write heat from the increased amount of the base heater control value upon contact determination by the contact determination unit.