Center frequency adjustment for a notch filter
AssigneeInternational Business Machines Corporation
InventorMasashi Kisaka
Life of this patent
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Abstract
Disclosed is a data storage device, a servo control method, and a program to reduce effects of a resonance frequency of an actuator or the like without reduction in servo control performance. A band-pass filter comprising a first all pass filter (APF) and a second adder, a second APF, and a multiplier are used to detect how much a current resonance frequency of the actuator deviates from a set value of a center frequency of the first APF, and based on a result of the detection, the center frequency of the first APF is properly adjusted. The adjustment of the center frequency of first APF enables a center frequency of a notch filter comprising the first APF and a first adder to be automatically approximated to a current resonance frequency of the actuator.
Claims11
A data storage device comprising:
- an actuator for supporting and moving a head for reading and writing data with respect to a recording medium;
- a servo control unit for feeding back a position error signal obtained by scanning the recording medium by the head to control an operation of the actuator;
- a notch filter for reducing a gain of a preset center frequency component from a servo signal transmitted from the servo control unit;
- deviation detecting means for detecting deviation of a resonance frequency of the actuator from a center frequency set in the notch filter;
- wherein the deviation detecting means comprises:
- a band-pass filter for passing a center frequency component corresponding to the resonance frequency from the servo signal transmitted from the servo control unit;
- a phase shifter for receiving a signal containing the resonance frequency as an input, and for shifting a phase at the resonance frequency of the signal by a predetermined amount;
- and
- a multiplier for multiplying the signal passed through the band-pass filter by the signal passed through the phase shifter;
- and
- changing means for changing a set value of the center frequency set in the notch filter based on a result of the deviation detection by the deviation detecting means.
A servo control method comprising:
- extracting a resonance frequency of a structure contained in a servo signal;
- detecting deviation of the resonance frequency from a center frequency set in a notch filter;
- and
- shifting the center frequency of the notch filter to the resonance frequency side;
- and
- wherein the servo signal is passed through a band-pass filter.
A computer program comprising:
- a means of extracting a resonance frequency of a structure contained in a servo signal;
- a means of detecting deviation of the resonance frequency from a center frequency set in a notch filter;
- and
- a means of shifting the center frequency of the notch filter to the resonance frequency side;
- and
- wherein the means of extracting the resonance frequency of the structure contained in the servo signal passes the servo signal through a band-pass filter.
Dependencies are inferred from the claim text.