Patent ID: 7869156

Claim:
A disk device, comprising: a head for at least reading information of a disk; an actuator for moving said head to a desired position on said disk; a correction table for storing correction signals acquired from a filter function in time units, that is created from the measured frequency characteristics of a position control system of said head and repetition frequency of the rotation of said disk, and the measured position error component synchronizing rotation of said disk; and a control unit for calculating a position error between a target position and a current position based on the position signals from said head and controlling said head position based on said position error and said correction signal, wherein said correction table stores said generated correction signal RRO by the filter function in time unit F(x) defined by the following Expression (13), where RPE is an average waveform of said position error signal, RRO is a correction signal, Ns is a number of servo sectors of one rotation of a track of said disk, and a(m)+jb(m) is said frequency characteristics, that is m times of the rotation frequency of said disk: ⁢ R ⁢ ⁢ R ⁢ ⁢ O ⁡ ( q ) = ∑ k = 0 N s - 1 ⁢ ⁢ R ⁢ ⁢ P ⁢ ⁢ E ⁡ ( k ) ⁢ F ⁡ ( k - q ) ⁢ ⁢ F ⁡ ( x ) = ∑ m = 1 N s / 2 - 1 ⁢ { a ⁡ ( m ) ⁢ cos ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ mx / N s ) - b ⁡ ( m ) ⁢ sin ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ mx / N s ) } ⁢ ( 2 / N s ) . ( 13 )