Patent ID: 6714493
Filing Date: 2004-03-30
Classification: G11B

Abstract:
An optical disk apparatus comprising:a light irradiator operable to converge a light beam and irradiate an information carrier with the converged light beam; a moving means operable to move a converging point of the light beam in a direction substantially perpendicular to a surface of the information carrier; and a focusing controller operable to control the moving means to place the converging point of the light beam at a predetermined position, wherein the focusing controller includes: a converging state detector operable to generate a detection signal corresponding to a converging state of the light beam on the information carrier; a focusing driving means operable to generate a driving signal for driving the moving means based on the detection signal; an integrator operable to integrate an absolute value of a signal corresponding to the driving signal over a predetermined time period; and an abnormal state detector operable to detect an abnormal state of the moving means based on an output of the integrator, the abnormal state being caused by a disturbance due to a higher degree component of waver of the optical disk.