| 摘要 |
PURPOSE:To decrease the transient response of a head positioning servo by subtracting an external disturbance cancelling signal and a speed signal from the driving current signal of a servo motor, integrating the result and adding the external cancelling signal being the result of subtracting the speed signal from a speed estimating signal obtained in this way. CONSTITUTION:A current detector 2 detects the driving current J1 of the servo motor 9 and a speed detector 3 detects the speed signal U0 of the motor 9 from the signal of a disk face written with a bit of position information. When any external disturbance exists, a difference is caused between the signal U0 and the speed estimating signal U1, the external disturbance cancelling signal F is caused in the output of an error amplifier 6 and the signal is fed to a power amplifier 1 via an adder 7. A speed signal the inverse of U0 produced from the polarity inverting circuit 8 eliminates the current signal component against the dynamic friction proportional to the speed in existence in the correction current detection signal J2 fed to an integrating device 5 to eliminate the effect of the dynamic friction onto the response of the signal F. Thus, the transient response of the head positioning servo mechanism is decreased.
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