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US 9,177,581 B2Granted
Head position demodulation method and magnetic disk device
AssigneeKabushiki Kaisha Toshiba
InventorTomoyoshi Yamada
Life of this patent
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Abstract
According to one embodiment, at demodulation of an A-phase burst pattern and a B-phase burst pattern arranged in a down-track direction so as to be different from each other in phase in a cross-track direction, the demodulated position of a magnetic head is calculated based on a sin component and a cos component in the A-phase burst pattern and a sin component and a cos component in the B-phase burst pattern.
Claims18
A head position demodulation method comprising:
- at demodulation of an A-phase burst pattern and a B-phase burst pattern arranged in a down-track direction so as to be different in phase in a cross-track direction, calculating a demodulated position of a magnetic head based on a sin component and a cos component of the A-phase burst pattern and a sin component and a cost component of the B-phase burst pattern,
- wherein, assuming that phase differences in the A-phase burst pattern and the B-phase burst pattern in the down-track direction are designated as Δφa and Δφb, respectively, when absolute values of Δφa and Δφb are equal, a cos component of a readback signal in the A-phase burst pattern is designated as cA and a sin component of the same as sA, a cos component of a readback signal in the B-phase burst pattern is designated as cB and a sin component of the same as sB, and sgn=+1 if Δφa/Δφb≧0 and −1 if Δφa/Δφb<0, the demodulated position of the magnetic head is calculated using coefficients ca, sa, cb, and sb based on N and Q calculated as:
- N=cA·ca−sA·sa+cB·cb−sB·sb·sgn
- Q=cA·sa+sA·ca+cB·sb+sB·cb·sgn.
1 more element
A magnetic disk device, comprising:
- a magnetic head;
- a magnetic disk in which an A-phase burst pattern and a B-phase burst pattern different from each other in phase in a cross-track direction are recorded;
- and
- a control unit that, at demodulation of the A-phase burst pattern and the B-phase burst pattern, calculates the demodulated position of the magnetic head based on a sin component and a cos component in the A-phase burst pattern and a sin component and a cos component in the B-phase burst pattern, wherein, assuming that phase differences in the A-phase burst pattern and the B-phase burst pattern in the down-track direction are designated as Δφa and Δφb, respectively, when absolute values of Δφa and Δφb are equal, a cos component of a readback signal in the A-phase burst pattern is designated as cA and a sin component of the same as sA, a cos component of a readback signal in the B-phase burst pattern is designated as cB and a sin component of the same as sB, and sgn=+1 if Δφa/Δφb≧0 and −1 if Δφa/Δφb<0, the control unit calculates the demodulated position of the magnetic head using coefficients ca, sa, cb, and sb based on N and Q calculated as:
- N=cA·ca−sA·sa+cB·cb−sB·sb·sgn
- Q=cA·sa+sA·ca+cB·sb+sB·cb·sgn.
3 more elements
Dependencies are inferred from the claim text.