Adaptive fly height for error recovery in a disc drive

• US 6,760,174 B2
• Filed: 01/25/2002
• Issued: 07/06/2004
• Est. Priority Date: 08/06/2001
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Forehand, Monty A.
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): Figueroa, Natalia
• Application Number:
  US10/057,271
• Publication Number:
  US 20030026018A1
• Time in Patent Office: 893 Days
• Field of Search: 360/31.25, 360/53.46, 360/75, 360/77.04, 360/78.08, 360/77.07, 360/97.01, 360/97.02, 360/69, 360/39, 360/71, 360/135, 360/78.04
• US Class Current: 360/53
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: G11B 21/21 with provision for maintaining desired spacing of head from record carrier, e.g. fluid-dynamic spacing, slider
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106
• CPC Class Codes: G11B 5/4833 Structure of the arm assembly, e.g. load beams, flexures, parts of the arm adapted for controlling vertical force on the head G11B5/484 takes precedence
• CPC Class Codes: G11B 5/58 with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following spacing means incorporated in the head structure G11B5/187, G11B5/255, G11B5/3106
• CPC Class Codes: G11B 5/6005 Specially adapted for spacing from a rotating disc using a fluid cushion

Abstract

A method of recovering data from a data sector through adaptive fly height to improve reliability of a disc drive is disclosed. Encountering a data error in a data sector initializes an error recovery routine that increases a fly height of the read/write head for asperity encounters, or decreases the fly height of the read/write head for low amplitude read signal encounters. In the case of asperity encounters, when the increased fly height fails data recovery, the read/write head is positioned off track, then lowered to burnish the asperity and the data sector is re-read.

Claims

1. A method comprising:

encountering a data error while reading data from a data sector of a disc with a read/write head of a data storage device;

categorizing the data error as an asperity; and

raising a fly height of the read/write head in response to the asperity on the disc to re-read the data from the data sector.

2. A device comprising a data transducing head adjacent a data sector of a medium and a control circuit which, upon categorizing as an asperity a data error encountered while reading data from the data sector, raises the fly height of the head and directs the head to re-read the data from the data sector at the raised fly height.