抄録
A control system which improves playability of optical disk drives is proposed. The system estimates the state variables such as a sensor-less disturbance observer and feeds them back to the controller. This approach improved control performance toward the defects on the optical disk by the feedback control of the estimated velocity. Furthermore, the influence of an acceleration disturbance to act on the drive and the influence of acceleration caused by physical distortion of the optical disk are suppressed by the feedback control of the estimated disturbance. It is proved that, by applying this control system to the tracking servo system of CD players, the control errors against the acceleration disturbance and the radial run-out of the disk were eliminated and that, as a result, abnormal sound skips never occurred on the defective disks. This control system is one of the key technology toward the realization of the high density optical disk drives.
