FOCUS SERVO SYSTEM AND FOCUS SERVO METHOD

PROBLEM TO BE SOLVED: To provide an optical disk focus servo system and an optical disk focus servo method by which precise focus servo is carried out in optical disk focus servo. SOLUTION: In servo loop design, a maximum gain is made to be 60 dB like a conventional manner, and a gain and a phase margin are set to be large. Since focus servo deflection of 12 dB remains as it is, focus servo deflection after pull-in of focus is stored in a memory with the angular position of an optical disk and slide stage positional information, data stored in the memory is synchronized with the angular position and the slide position of the optical disk after pull-in again of focus. Then, an optical pickup driving means controls the whole optical pickup in a focusing direction to control the focus servo deflection to be small. As the result of this, precise focus servo capable of attenuating a basic wave frequency component of ≥72 dB is carried out. COPYRIGHT: (C)2007,JPO&INPIT