Patent Document ID: 20090154313
Application ID: 12333554
Patent Flag: 0

Claim One:
1. An optical disc apparatus for recording or reading information to or from an optical disc by irradiating the disc with laser light, said optical disc apparatus comprising: an optical detection module to produce an electrical output signal corresponding to the amount of light reflected from the optical disc; a servo error signal creation module to create a servo error signal from the output signal from the optical detection module; a feedback control module to create a drive signal for driving a servo actuator based on the servo error signal and to provide feedback control; a disc rotation module to rotate the optical disc; an addition module to add a compensation signal to a given signal within a servo loop, said compensating signal acting to compensate for periodical external disturbances entered to a servo system of the optical disc apparatus; a storage module to store an output signal from the addition module for an interval of time corresponding to at least one rotation of the optical disc; and an iterative learning control module to provide control of iterative learning control; wherein said iterative learning control module modifies filter characteristics set to said feedback control module to given filter characteristics providing increased gains; wherein outputting of the iterative learning control is started after a lapse of the period of at least one rotation after the modification of the filter characteristics; and wherein the filter characteristics set to said feedback control module are modified to steady-state servo characteristics after a lapse of a given time since the start of the outputting of the iterative learning control.