Magnetic disk drive and method of controlling the same
View Patent ↗Embodiments of the present invention provide a magnetic disk drive, in which a disturbance component contained in an output signal from a rotational vibration detector, can be appropriately suppressed irrespective of frequency of the component, and a method of controlling the drive. According to one embodiment, in a magnetic disk drive having a rotational vibration detector for detecting rotational vibration of a drive housing, a main control circuit performs a head moving step of driving a voice coil motor to move a magnetic head on a magnetic disk, a frequency estimation step of estimating a frequency of each disturbance component contained in an output signal from the rotational vibration detector after moving the magnetic head, and a suppressor setting step of setting a notch filter for suppressing the disturbance component based on the estimated frequency.
1. A method of controlling a magnetic disk drive comprising a magnetic disk, a magnetic head, a support mechanism that supports the magnetic head on the magnetic disk and is rotatable about a rotation axis fixed outside the magnetic disk, a head actuator that rotatably drives the support mechanism to move the magnetic head in an approximately radial direction of the magnetic disk, and a rotational vibration detector that detects rotational vibration of a drive housing about the rotation axis, wherein an output signal from the rotational vibration detector is used for controlling the head actuator, wherein the method comprises:
a head moving step of driving the head actuator to move the magnetic head on the magnetic disk,
a frequency estimation step of estimating a frequency of each disturbance component contained in the output signal from the rotational vibration detector after moving the magnetic head,
a convergence determination step of determining the convergence of the estimated frequency, and
a suppressor setting step of setting a disturbance suppressor for suppressing the disturbance component based on the estimated frequency.
2. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
the convergence determination step of determining the convergence of the estimated frequency includes performing calculation of an absolute value of dB and comparing the absolute value of dB to a threshold value.
3. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
the disturbance suppressor is configured by a digital filter, and
the suppressor setting step includes setting a parameter included in a transfer function of the digital filter according to the estimated frequency.
4. The method of controlling a magnetic disk drive according to claim 3 , characterized in that:
the parameter is determined for each frequency such that the digital filter suppresses a signal component in a predetermined frequency band including the relevant frequency.
5. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
the frequency estimation step includes changing a mode between a mode where an estimated value is approximated to a frequency of a relatively large disturbance component in the disturbance components contained in the output signal from the rotational vibration detector, and a mode where the estimated value is allowed to match with the frequency of the relevant large disturbance component.
6. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
the head moving step is repeated until the frequency of the disturbance component is estimated in the frequency estimation step.
7. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
when the output signal from the rotational vibration detector contains a plurality of disturbance components being different in frequency, aiming at the output signal from the rotational vibration detector, the head moving step, the frequency estimation step, and the suppressor setting step are performed, so that a first disturbance suppressor is set so as to suppress a first disturbance component, and then
aiming at an output signal from the first disturbance suppressor, the head moving step, the frequency estimation step, and the suppressor setting step are performed, so that a second disturbance suppressor is set so as to suppress a second disturbance component.
8. The method of controlling a magnetic disk drive according to claim 1 , characterized in that:
the rotational vibration detector is installed on the device housing, or a substrate attached to the device housing.
9. A magnetic disk drive, comprising:
a magnetic disk,
a magnetic head,
a support mechanism that supports the magnetic head on the magnetic disk, and is rotatable about a rotation axis fixed outside the magnetic disk,
a head actuator that rotatably drives the support mechanism to move the magnetic head in an approximately radial direction of the magnetic disk,
a rotational vibration detector that detects rotational vibration of a drive housing about the rotation axis,
an apparatus configured to drive the head actuator to move the magnetic head on the magnetic disk,
an apparatus configured to estimate a frequency of each disturbance component contained in an output signal from the rotational vibration detector after moving the magnetic head, and
an apparatus configured to set a disturbance suppressor for suppressing the disturbance component based on the estimated frequency;
wherein an output signal from the disturbance suppressor is used for controlling the head actuator;
wherein the apparatus configured to estimate a frequency of each disturbance component compares an absolute value of dB to a threshold value, and thereby determines whether the estimated frequency is converged or not.
10. The magnetic disk drive according to claim 9 , characterized in that:
the disturbance suppressor is configured by a digital filter, and
the apparatus configured to set a disturbance suppressor is configured to set a parameter included in a transfer function of the digital filter according to the estimated frequency.
11. The magnetic disk drive according to claim 10 , characterized in that:
the parameter is determined for each frequency such that the digital filter suppresses a signal component in a predetermined frequency band including the relevant frequency.
12. The magnetic disk drive according to claim 9 , characterized in that:
the apparatus configured to estimate the frequency is configured to change a mode between a mode where an estimated value is approximated to a frequency of a relatively large disturbance component in the disturbance components contained in the output signal from the rotational vibration detector, and a mode where the estimated value is allowed to match with the frequency of the relevant large disturbance component.
13. The magnetic disk drive according to claim 9 , characterized in that:
apparatus configured to move the head is configured to repeat movement until the frequency of the disturbance component is estimated in the frequency estimation step.
14. The magnetic disk drive according to claim 9 , characterized in that:
the rotational vibration detector is installed on the device housing, or on a substrate attached to the device housing.