System, method and apparatus for determining track pitch in a hard disk drive to satisfy the requirements of both off-track capacity and adjacent track erasure
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsShanlin Duan, Zhen Jin, Jane Jie Zhang, Kezhao Zhang
Life of this patent
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Abstract
Track pitch in a hard disk drive is selected to satisfy the requirements of both off-track capacity (OTC) and adjacent track interference (ATI). The invention separately measures the track pitch requirements for OTC and ATI. The track pitch for the drive is set with the larger of the OTC and ATI track pitches. The OTC track pitch is measured with a 747 curve, and the ATI track pitch is measured by the positions of adjacent tracks at which the on-track error rate is not worse than a given value after the targeted number of adjacent track writes in the ATI requirement.
Claims16
A method of determining track pitch in a hard disk drive, comprising:
- (a) measuring an off-track capacity (OTC) track pitch of a magnetic media disk to ensure sufficient soft error rate (SER) at off-track locations;
- (b) measuring an adjacent track interference (ATI) track pitch of the magnetic media disk to ensure sufficient on-track SER after adjacent tracks are written multiple times;
- (c) defining a final track pitch for the hard disk drive as a larger one of the OTC track pitch and the ATI track pitch.
A method of determining track pitch in a hard disk drive, comprising:
- (a) providing a hard disk drive;
- (b) measuring a 747 curve and determining an off-track capacity (OTC) track pitch of the hard disk drive;
- (c) measuring an adjacent track interference (ATI) track pitch with a plurality of adjacent track writes;
- (d) fitting a logarithmic function to the ATI track pitch and data from the number of adjacent track writes;
- (e) calculating ATI track pitch for a desired number of adjacent track writes using a fitted function;
- and then
- (e) selecting a final track pitch from a greater of the OTC and ATI track pitches;
- and
- the 747 curve is a plot of OTC versus squeeze track pitch (SQTP), and an intersection of the 747 curve and a value of 15% of a SQTP line is defined as a demo track pitch.
A method of determining track pitch in a hard disk drive, comprising:
- (a) providing a hard disk drive;
- (b) measuring a 747 curve and determining an off-track capacity (OTC) track pitch of the hard disk drive;
- (c) measuring an adjacent track interference (ATI) track pitch with a plurality of adjacent track writes by measuring positions of adjacent tracks at which an on-track error rate is not worse than a given value after a targeted number of adjacent track writes in an ATI requirement;
- (d) fitting a logarithmic function to the ATI track pitch and data from the number of adjacent track writes;
- (e) calculating ATI track pitch for a desired number of adjacent track writes using a fitted function;
- and then
- (e) selecting a final track pitch from a greater of the OTC and ATI track pitches;
- and
- an error rate degradation is less than about 0.7 for an original error rate of about −5, and both the OTC and ATI track pitches are derived from operations of the hard disk drive.
Dependencies are inferred from the claim text.