Extracting repeatable phase error from a spindle motor back EMF signal to generate a servo write clock
AssigneeWestern Digital Technologies, Inc.
InventorMark R. McCornack
Life of this patent
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Abstract
A method of writing servo data onto a disk is disclosed. A spindle motor spins the disk, and a back electromotive force (BEMF) signal is measured from the spindle motor. A repeatable phase error (RPE) is extracted from the BEMF signal to generate an adjusted BEMF signal. A servo write clock is synchronized in response to the adjusted BEMF signal, and the servo data is written to the disk using the servo write clock. In one embodiment, the servo data comprises spiral seed patterns that are processed to write concentric servo sectors to the disk.
Claims20
A method of writing servo data onto a disk, the method comprising:
- spinning the disk with a spindle motor;
- measuring a back electromotive force (BEMF) signal from the spindle motor;
- extracting a repeatable phase error (RPE) from the BEMF signal to generate an adjusted BEMF signal;
- synchronizing a servo write clock in response to the adjusted BEMF signal;
- and
- writing the servo data to the disk using the servo write clock.
A servo data writer for writing servo data onto a disk, the servo data writer comprising:
- a spindle motor for spinning the disk;
- a back electromotive force (BEMF) detector operable to detect a BEMF signal from the spindle motor;
- timing circuitry operable to extract a repeatable phase error (RPE) from the BEMF signal to generate an adjusted BEMF signal, and synchronize a servo write clock in response to the adjusted BEMF signal;
- and
- write circuitry operable to write the servo data to the disk using the servo write clock.
Dependencies are inferred from the claim text.