Reducing seek time of tracking actuator with pulsed excitation in optical disk

The latency time, which is the residual vibration of a fine actuator and track eccentricity, has been the aim for direct pull-in in optical disk systems. Modified velocity profiles of the coarse actuator and control inputs of the fine actuator have been proposed for the minimum residual vibration. Generally, there exists eccentricity due to mismatch of the disk center and the axis of a spindle motor. So, if a fine actuator is locked to the coarse actuator, another latency time must be need because of the track eccentricity. The track eccentricity can be estimated as the rotation type of the spindle motor changes from CLV to CAV. In this paper, the fine actuator is excited with the same velocity of the track and the track pull-in is executed without any latency