Method to detect junction induced signal instability from...

Details Method to detect junction induced signal instability from... Method to detect junction induced signal instability from...

2001-04-26

2002-12-03

Lefkowitz, Edward (Department: 2862)

Electricity: measuring and testing

Magnetic

Magnetic information storage element testing

Reexamination Certificate

active

06489762

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a method for measuring different characteristics of a magneto-resistive head for a hard disk drive.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. There have been developed magnetic heads that have a write element for magnetizing the disks and a separate read element for sensing the magnetic fields of the disks. The read element is typically constructed from a magneto-resistive material. The magneto-resistive material has a resistance that varies with the magnetic fields of the disk. Heads with magneto-resistive read elements are commonly referred to as magneto-resistive (MR) heads.
FIG. 1
shows an MR head
1
which has an abut junction design. This type of MR head has a pair of permanent magnets
2
located on either side of a sensor element
3
. The permanent magnets provide a hard bias field that stabilize the sensor element
3
.
Magnetic heads are typically tested before being assembled into disk drives. Errors in the manufacturing processes may create instabilities in the biasing junction. The stability of the heads are typically tested to screen for defective parts. Stability factors such as amplitude covarian and base line popping noise are tested by loading a head onto a test stand and performing test routines. The test routines include the steps of writing a signal on a track and then reading the signal with the magneto-resistive read element of the head. The signal is typically read when the read element is aligned with the center of the track. Such a procedure does not test for junction effects and is generally not effective in determining an instability of the head.
BRIEF SUMMARY OF THE INVENTION
One embodiment of the present invention is a method for measuring a characteristic of a magnetic head of a hard disk drive. The method includes the step of writing a signal onto a track of a disk. The track has left and right track edges. The magnetic head is moved to align junction areas of the head with the track edges. The characteristic is then measured. These steps may be repeated to align various junction areas with track edges and to measure various characteristics of the head.


REFERENCES:
patent: 4813782 (1989-03-01), Yagi et al.
patent: 5055969 (1991-10-01), Putnam
patent: 5122915 (1992-06-01), Klein et al.
patent: 5233482 (1993-08-01), Galbraith et al.
patent: 5301080 (1994-04-01), Ottesen et al.
patent: 5309295 (1994-05-01), Bailey et al.
patent: 5327303 (1994-07-01), Smith
patent: 5335121 (1994-08-01), Bombeeck
patent: 5367409 (1994-11-01), Ottesen et al.
patent: 5388127 (1995-02-01), Scarpa
patent: 5422764 (1995-06-01), Mcllvanie
patent: 5426542 (1995-06-01), Smith
patent: 5430592 (1995-07-01), Yoda
patent: 5475488 (1995-12-01), Fukuzawa et al.
patent: 5497111 (1996-03-01), Cunningham
patent: 5499161 (1996-03-01), Hosseinzadeh et al.
patent: 5557399 (1996-09-01), de Groot
patent: 5566101 (1996-10-01), Kodra
patent: 5583720 (1996-12-01), Ishida et al.
patent: 5590154 (1996-12-01), Forni et al.
patent: 5729410 (1998-03-01), Fontana, Jr. et al.
patent: 5737837 (1998-04-01), Inaba
patent: 5757582 (1998-05-01), White et al.
patent: 5760982 (1998-06-01), Stein
patent: 5781133 (1998-07-01), Tsang
patent: 5822143 (1998-10-01), Cloke et al.
patent: 5844920 (1998-12-01), Zook et al.
patent: 5862007 (1999-01-01), Pham et al.
patent: 5898532 (1999-04-01), Du et al.
patent: 5914594 (1999-06-01), Mian
patent: 5926348 (1999-07-01), Shouji et al.
patent: 5961658 (1999-10-01), Reed et al.
patent: 6078473 (2000-06-01), Crane et al.
patent: 6118624 (2000-09-01), Fukuzawa et al.
patent: 6181532 (2001-01-01), Dovek et al.

Affiliated with

Also associated with

Rating

Method to detect junction induced signal instability from... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method to detect junction induced signal instability from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method to detect junction induced signal instability from... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2945305