Abstract: A head position control method performs virtual circular control which does not follow up the eccentricity of a disk, and implements high precision virtual circular control, even if the servo signals of an area demodulation method are used. The method performs virtual circular control by demodulating position signals in the area demodulation method and calculates the demodulation position with the velocity offset correction of 2-phase servo signals by using both the head velocity V of the virtual circular orbit reference and the relative velocity &Dgr;V of the virtual circular orbit and the position signal.

Abstract: Disclosed herein is a calibration method for a two-stage actuator control system. The calibration method includes the steps of inserting a sinusoidal disturbance dv(k) into a control input uv(k) to a main actuator, comparing uv(k) and uv(k)+dv(k) to obtain an open-loop gain, and setting the reciprocal of the open-loop gain in a gain compensator for the main actuator. The calibration method further includes the steps of adding a sinusoidal disturbance dp(k) to an input to a subactuator, and comparing the sinusoidal disturbance dp(k) with an output y(k) from the two-stage actuator to obtain a disturbance input-displacement gain. A design nominal value is divided by the disturbance input-displacement gain to obtain a compensation gain, which is then set in a gain compensator for the subactuator.

Abstract: Position information PosN and PosQ are compared and position information Pos1 and Pos2 in which influences of an error of a position sensitivity gain appear oppositely are calculated. Subsequently, a weight gain G1=M and a weight gain G2=(1−M) are obtained from the position information Pos1. A multiplication value obtained by multiplying the third position information Pos1 by the weight gain G1 and a multiplication value obtained by multiplying the fourth position information Pos2 by the weight gain G2 are added and synthesized, thereby calculating a decoded position.

Abstract: A resonance-frequency measuring method is used for measuring a resonance frequency of an information recording/reproducing device reproducing information recorded on a medium by driving a mechanism unit. The resonance-frequency measuring method comprises the measuring step of applying sine-wave oscillations at different frequencies one by one to the mechanism unit, and counting the number of times information reproduced upon application of each of the sine-wave oscillations differs from information indicating an aimed location, and the resonance-frequency determining step of determining the resonance frequency according to the number of times counted in the measuring step.

Abstract: A disk device includes a head part, an actuator part for moving the head part to an objective position, and a control part for controlling the actuator part, wherein the control part makes the actuator part shift to a reverse direction of the movement direction of the head part before a settling action of the head part starts being implemented.

Abstract: This invention relates to a disk drive and a method of writing data to the disk drive. In a disk drive including a write head, a read head and a positioning unit of a head which includes a write element and a read element, the present invention provides the disk drive with a position error measuring unit for measuring the amount of a position error of the write element and the read element; and a write/read control unit for obtaining an offset amount of the head in accordance with the amount of the position error of the head, setting the offset amount to the positioning unit so as to offset the head, and effecting data write/read operation. When format write operation is executed, only an ID portion is offset in the same direction as the direction of the position error so measured in accordance with the measured amount of the position error, and is written.