Patent ID: 7215501

Claim:
A disk device comprising: a head for reading a plurality of servo information which have a series of servo information numbers and are recorded on a disk; a phase learning means for learning a phase error amount which is a phase difference between a sawtooth waveform indicating variations in the servo information number that is read by the head and a sinusoidal wave indicating variations in the amount of eccentricity of the disk; a subtraction means for detecting a positional error of the head on the basis of a target position of the head that is supplied from the outside, and the current position of the head; a sinusoidal wave generation means for generating an eccentricity sync sinusoidal wave having the phase error amount learned by the phase learning means, at a frequency synchronized with a rotation frequency of the disk; an eccentricity control amount calculation means for calculating a weight factor on the basis of the eccentricity sync sinusoidal wave and the positional error of the head, and multiplying the eccentricity sync sinusoidal wave by the weight factor to obtain an eccentricity control amount; a positioning control means for controlling positioning of the head on the basis of the positional error of the head and the eccentricity control amount; and an eccentricity control amount initial learning means for previously storing the phase error amount learned by the phase learning means, and a weight factor of each of plural areas into which the disk is concentrically divided; wherein, during a settling operation, said eccentricity control amount calculation means reads a phase error amount and a weight factor corresponding to the target position of the head from the eccentricity control amount initial learning means, and calculates an eccentricity control amount using the phase error amount and the weight factor which have been read out.