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Disk drive measuring reader/writer gap by measuring fractional clock cycle over disk radius

  • US 9,013,818 B1
  • Filed: 12/20/2013
  • Issued: 04/21/2015
  • Est. Priority Date: 12/06/2013
  • Status: Active Grant
First Claim
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1. A disk drive comprising:

  • a disk;

    a head actuated radially over the disk, wherein the head comprises a read element separated from a write element by a reader/writer gap; and

    control circuitry configured to;

    synchronize a disk-locked clock to a rotation of the disk, wherein;

    the disk-locked clock comprises a plurality of clock cycles; and

    the reader/writer gap spans a first number of the clock cycles comprising an integer of the clock cycles plus a fraction of one of the clock cycles;

    measure the fraction of one of the clock cycles when the head is positioned at a first plurality of radial locations across the disk; and

    estimate a second plurality of radial locations where the fraction substantially equals a full one of the clock cycles.

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