Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2005-01-25
2005-01-25
To, Doris H. (Department: 2655)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S044360, C708S309000, C708S311000, C360S078090
Reexamination Certificate
active
06847598
ABSTRACT:
The present invention implements a servo system which can support changes of the higher resonance frequencies of the actuator with a simple configuration at low cost. The servo system comprises a head3which at least reads a disk1,a carriage5which drives the head3to the track position of the disk1,a detection circuit9which detects a positional error with respect to the track from the read output of the head, and the servo control unit11which controls the carriage such that the head follows up the track according to the positional error, wherein the servo control unit11further comprises a digital filter for increasing gain so that the open loop characteristic of the tracking servo system by the servo control unit has a gain higher than the open loop gain of the phase cross-over frequency f6in a frequency area which is higher than the phase cross-over frequency f6but lower than the higher resonance frequency f9of the carriage and where the gain does not becomes OdB or more at a frequency where phase is (−180+360×N)°. Since gain is increased, phase margin is increased.
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Patel Gautam R.
To Doris H.
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