| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive controller for pickup head accomplishing a controllability which has been difficult conventionally in an information recorder required to be of a high speed and high density. SOLUTION: The controller is arranged to estimate and compensate for the disturbance/speed of a state observing unit by connecting a reverse system of second resonance characteristics in series. With regard to the frequency characteristics, a steep phase lead variation is provided such that the phase intersects 0 deg. in the vicinity of the resonance point of a control object when the low frequency phase is -90 deg. or above and has an abrupt phase advance so as to abruptly advance by +90 deg. or more in front of a second resonance point.
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