Claims
- 1. A method for improving read error rates in a disc drive employing repeatable run-out compensation for writing but not for reading, comprising steps of:(a) implementing a repeatable run-out compensation system that compensates for repeatable run-out during write operations but not during read operations; and (b) after implementing the repeatable run-out compensation system, performing reader-to-writer offset calibration.
- 2. The method of claim 1 further comprising a step (c), prior to step (a), of performing reader-to-writer offset calibration, and wherein performing step (b) comprises performing additional reader-to-writer offset calibration after implementing the repeatable run-out compensation system to account for changes in reader-to-writer offset resulting from implementation of the repeatable run-out compensation system.
- 3. The method of claim 1 wherein performing step (b) comprises:(b)(i) experimentally determining read error rates for a given data track across a range of reader-to-writer offset values; and (b)(ii) determining an optimum reader-to-writer offset based on the experimentally determined read error rates.
- 4. The method of claim 3 wherein determining step (b)(ii) comprises:(b)(ii)(A) generating a curve representing read error rates as a function of reader-to-writer offset; and (b)(ii)(B) determining the optimum reader-to-writer offset based on the shape of the curve.
- 5. The method of claim 1 wherein performing step (b) comprises performing reader-to-writer offset calibration at each track of a disc surface.
- 6. The method of claim 1 wherein performing step (b) comprises performing reader-to-writer offset calibration at fewer than all of the tracks of a disc surface and interpolating the reader-to-writer offset at tracks lying between the calibrated tracks.
- 7. A disc drive comprising:a disc adapted to store data and including a servo track adapted to store servo information used to indicate the position of a head relative to the servo track; a head having a writer adapted to write data to the disc and a reader adapted to read data from the disc; an actuator adapted to position the head relative to a surface of the disc in response to a servo control signal; a repeatable run-out compensation circuit adapted to compensate for repeatable run-out of the servo track during write operations but not during read operations; and a servo controller adapted to generate a servo control signal based in part on a reader-to-writer offset that is calibrated while the compensation circuit is operational.
- 8. The disc drive of claim 7 wherein the disc includes a plurality of servo tracks, wherein the reader-to-writer offset is calibrated for each of the plurality of servo tracks and wherein the servo controller is adapted to generate a servo control signal based in part on the reader-to-writer offset corresponding to the servo track that the head is being positioned over.
- 9. The disc drive of claim 7 wherein the disc includes a plurality of servo tracks, wherein an actual reader-to-writer offset is calibrated for fewer than all of the plurality of servo tracks, wherein interpolated reader-to-writer offsets are interpolated for tracks lying between the calibrated tracks and wherein the servo controller is adapted to generate a servo control signal based in part on the actual or interpolated reader-to-writer offset corresponding to the servo track that the head is being positioned over.
- 10. A disc drive comprising:a repeatable run-out compensation circuit adapted to compensate for repeatable run-out of a servo track on a disc surface during write operations but not during read operations; and means for calibrating a reader-to-writer offset of a data head while the compensation circuit is operational.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Patent Application No. 60/121,026 entitled “READ ERROR RATES WHEN USING WRITE ZAP AND NO READ ZAP,” filed on Feb. 22, 1999.
The following U.S. patent applications, assigned to the same assignee as the present invention, are related to the present application:
U.S. patent application Ser. No. 09/106,443 entitled “COMPENSATION FOR REPEATABLE RUN-OUT ERROR,” filed on Jun. 29, 1998 now U.S. Pat. No. 6,069,764.
U.S. patent application Ser. No. 09/370,823 entitled “COMPENSATION FOR REPEATABLE RUNOUT ERROR,” filed on Aug. 9, 1999.
U.S. patent application Ser. No. 09/394,160 entitled “MULTI-RATE SERVO DISC DRIVE WITH MULTI-RATE WRITTEN-IN REPEATABLE RUN-OUT COMPENSATION,” filed on Sep. 13, 1999.
U.S. patent application Ser. No. 09/394,756 entitled “CONCENTRIC SPACING OF VIRTUAL DATA TRACKS USING RUN-OUT COMPENSATION,” filed on Sep. 13, 1999, now U.S. Pat. No. 6,392,834.
US Referenced Citations (9)
Provisional Applications (1)
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Number |
Date |
Country |
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60/121026 |
Feb 1999 |
US |