Method and apparatus for error recovery for unstable magnetorestrictive heads

• US 5,661,614 A
• Filed: 02/06/1995
• Issued: 08/26/1997
• Est. Priority Date: 05/31/1994
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Eaton, Robert Eugene, Hirko, Richard George, Wallash, Albert John
• Primary Examiner(s): Psitos, Aristotelis M.
• Assistant Examiner(s): WAMSLEY, PATRICK G
• Application Number:
  US08/384,309
• Time in Patent Office: 932 Days
• Field of Search: 360/27, 360/31, 360/53, 360/66, 360/77.06, 360/113, 324/76.83, 324/522, 324/537, 338/32 R
• US Class Current: 360/66
• CPC Class Codes: G11B 19/04 Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions
• CPC Class Codes: G11B 2005/0008 Magnetic conditionning of heads, e.g. biasing
• CPC Class Codes: G11B 2005/0016 of magnetoresistive transducers
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
• CPC Class Codes: G11B 5/09 Digital recording
• CPC Class Codes: G11B 5/455 Arrangements for functional testing of heads; Measuring arrangements for heads
• CPC Class Codes: G11B 5/465 Arrangements for demagnetisation of heads

Abstract

A method and apparatus is disclosed for recovering data with unstable low amplitude magnetorestrictive heads. After an error in data recovery is detected a technique is invoked that changes the bias current through the magnetoresistive head to the reverse direction in a predetermined manner. The method includes reversing the bias current direction, returning the bias current to its normal state and reading the data from the storage medium. Alternatively, the method includes reversing the bias current direction and reading the data when the bias current direction is reversed.

Claims

1. A method of recovering data from a magnetic storage device including magnetic medium for storing data and a magnetoresistive head for reading the data, and including a means for providing a bias current to the magnetoresistive head, the bias current being utilized to provide a signal that allows for the reading of the data, the method including the steps of:

(a) reversing the bias current direction through the magnetoresistive head for a predetermined time period;

(b) returning the bias current to a normal state;

(c) attempting to read the data from the medium;

(d) repeating steps (a-c) a first predetermined number of times when the data cannot be read;

(e) reversing the bias current through the magnetoresistive head when the first predetermined number of times is completed;

(f) attempting to read the data from the medium;

(g) returning the bias current to the normal state;

(h) determining if a second predetermined number of times has been reached when the data cannot be read;

(i) repeating steps (e) (f) and (g) until the second predetermined number of times has been reached; and

(j) returning to step (a) a desired number of times.