Correlation of sectored servo position information

• US 5,117,408 A
• Filed: 09/29/1989
• Issued: 05/26/1992
• Est. Priority Date: 09/29/1989
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Goss, Lloyd C., Weispfenning, Gerald L.
• Primary Examiner(s): Psitos, Aristotelis
• Assistant Examiner(s): Garland, Steven R.
• Application Number:
  US07/415,500
• Time in Patent Office: 970 Days
• Field of Search: 369/77.02-77.05, 369/77.07-77.11, 369/78.04-78.14, 369/135, 364/32, 364/33, 364/41, 364/43, 364/44.32, 364/44.34, 364/44.28
• US Class Current: 360/78.14
• CPC Class Codes: G11B 5/5556 with track following after a "seek"

Abstract

Transducer position is determined relative to a disk in a data storage system. Track identification information is read from a disk in the data storage system to provide a coarse position signal identifying a track that the transducer is positioned over. Position error samples are read from a disk in the data storage system to provide a fine position signal representing transducer position error within a track that the transducer is positioned over. Then, the coarse position signal and the fine position signal are correlated so they correspond to the same track on the disk.

Claims

1. A method of determining transducer position relative to a disk in a data storage system, comprising:

reading track identification information from a disk in the data storage system to provide a coarse position signal identifying a track that the transducer is positioned over;

reading position error samples from a disk in the data storage system to provide a fine position signal representing transducer position error within a track that the transducer is positioned over; and

correlating the coarse position signal and the fine position signal so the coarse position signal and the fine position signal correspond to the same track on the disk, the step of correlating comprising;

determining whether the transducer has moved between tracks after reading the track identification information and before reading the position error samples; and

adjusting the coarse position signal to reflect proper track identification information when the transducer has moved.

2. The method of claim 1 wherein the step of determining whether the transducer has moved further comprises:

determining a first sign bit corresponding to a first position error sample;

determining a second sign bit corresponding to a second position error sample;

determining a least significant bit of the track identification information; and

determining whether the transducer has moved between tracks based on the first sign bit, the second sign bit and the least significant bit of the track identification information.

3. The method of claim 2 wherein the step of adjusting the coarse position signal further comprises:

determining a correction number to be added to the coarse position signal, the correction number having a value based on the value of the first sign bit, the second sign bit and the least significant bit of the track identification information; and

combining the coarse position signal with the correction number to reflect the proper track identification information.

4. An apparatus for determining transducer position relative to a disk in a data storage system, comprising:

track reading means for reading track identification information from a disk in the data storage system to provide a coarse position signal identifying a track that the transducer is positioned over;

position error reading means for reading position error samples from a disk in the data storage system to provide a fine position signal representing transducer position error within a track that the transducer is positioned over; and

correlating means for correlating the coarse position signal and the fine position signal so the coarse position signal and the fine position signal correspond to the same track on the disk, the correlating means comprising;

boundary crossing means for determining whether the transducer has moved between tracks after reading the track identification information and before reading the position error samples; and

correction means for correcting the coarse position signal to reflect proper track identification information when the transducer has moved.

5. The apparatus of claim 4 wherein the boundary crossing means further comprises:

first sign bit detection means for detecting a first sign bit corresponding to a first position error sample;

second sign bit detection means for detecting a second sign bit corresponding to a second position error sample;

least significant bit detection means for detecting a least significant bit of the track identification information; and

first combination means for combining the first sign bit, the second sign bit and the least significant bit of the track identification information to determine whether the transducer has moved between tracks.

6. The apparatus of claim 5 wherein the correction means further comprises:

correction number determining means for determining a correction number having a value determined by the combination of the first sign bit, the second sign bit and the least significant bit of the track identification information; and

second combination means for combining the correction number with the coarse position signal to reflect the proper track identification information.