DLC-Head Offset Compensation While Writing
AssigneeLSI Corporation
InventorsJeffrey Grundvig, Richard Rauschmayer
Life of this patent
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Abstract
In described embodiments, effects of frequency and phase error introduced at the outer diameter or inner diameter of the disk when a read head is used to maintain timing lock while the write head is used to write new data might be eliminated with a simple compensation circuit. Compensation circuits, modules or methods receive as input information i) write head radial position (e.g., from a wedge number that indicates the circumferential position of the heads), and ii) read head and write head relative physical offset. The timing error is measured by the system and might be automatically adjusted by the appropriate amount in order to reduce or to eliminate the differential head error when a write event (as opposed to a read event) is activated
Claims20
A method of timing compensation when writing data during a write action to a hard disk of a hard disk drive, the method comprising:
- reading, by a read head, tracking data from the hard disk;
- generating timing control information for the read head from the tracking data, the timing control information employed to control a timing loop of the read head and a write head of the hard disk drive;
- determining a timing error profile corresponding to a current center slip of the hard disk based on i) a write head radial position, ii) a read and write head relative physical offset, and iii) the timing control information;
- generating the timing error profile based on the write head radial position, the relative physical offset, and the current timing information of the timing loop;
- and
- adjusting the timing control information for the read head based on the timing error profile.
Apparatus for timing compensation when writing data during a write action to a hard disk of a hard disk drive, the apparatus comprising:
- a read head configured to read tracking data from the hard disk;
- a media controller having a timing loop controller and an offset compensation processor,
- wherein the timing loop controller configured to generate timing control information for the read head from the tracking data, the timing control information employed to control a timing loop of the read head and a write head of the hard disk drive;
- wherein the offset compensation processor configured to determine a timing error profile corresponding to a current center slip of the hard disk based on i) a write head radial position, ii) a read and write head relative physical offset, and iii) the timing control information;
- wherein the offset compensation processor generates the timing error profile based on the write head radial position, the relative physical offset, and the current timing information of the timing loop;
- and
- wherein the timing loop controller adjusts the timing control information for the read head based on the timing error profile.
A machine-readable storage medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method for timing compensation when writing data to a hard disk of a hard disk drive, comprising the steps of:
- reading, by a read head, tracking data from the hard disk;
- generating timing control information for the read head from the tracking data, the timing control information employed to control a timing loop of the read head and a write head of the hard disk drive;
- determining a timing error profile corresponding to a current center slip of the hard disk based on i) a write head radial position, ii) a read and write head relative physical offset, and iii) the timing control information;
- generating the timing error profile based on the write head radial position, the relative physical offset, and the current timing information of the timing loop;
- and
- adjusting the timing control information for the read head based on the timing error profile.
Dependencies are inferred from the claim text.