High-speed focus pull-in controllers for adaptively responding to disk surface vibration of an optical disk device and focus control methods thereof

摘要

Upper and lower limit values of disk surface vibration are detected and stored per a predetermined time while a signal is reproduced from an optical disk device and, if focus on the disk deviates from a focus allowable range initially set, a focus repull-in operation is performed with reference to the upper and lower limit surface vibration values stored previously.