Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2003-12-31
2004-10-26
Tupper, R. S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S125330, C360S317000
Reexamination Certificate
active
06809899
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electromagnetic transducers for information storage and retrieval systems, such as disk or tape drives.
FIG. 1
is a schematic top view of a disk drive storage system
20
, including a spinning disk
22
coated with a media layer
23
and a transducer
25
held by an arm
28
for storing and retrieving information on the media. Such a drive system
20
may have another transducer for storing and retrieving information on another media layer on an opposite side of the disk
22
, and may have additional disks and associated transducers, not shown. The transducer
25
may be attached to a slider that is held near a free end of the arm
28
by a gimbal structure. The transducer
25
writes and reads data on multiple concentric tracks of the disk
22
such as track
30
. To instead write and read data on another track
31
that is near a center
33
of the disk
22
, the arm is driven by an actuator, not shown, to move the transducer toward the center
33
. By sweeping the arm
28
over the surface of the disk
22
, as shown by arrow
35
, the transducer
25
can access the multiple data tracks. The orientation of the transducer, however, is skewed relative to tracks such as
30
and
31
disposed near outer and inner radiuses of the media layer.
Current commercially available disk drives store data in domains having magnetizations that are substantially parallel to tracks such as tracks
30
and
31
, which is sometimes called longitudinal recording. It has been predicted that such longitudinal magnetic storage will become unstable at normal operating conditions when the domains reach a minimal size, termed the superparamagnetic limit. In order to store the data at higher density, the drive system
20
may instead be designed to store data in domains that are substantially perpendicular to the disk
22
surface, which may be termed perpendicular recording.
FIG. 2
is a schematic side view of a prior art system for perpendicular recording, including a transducer
50
positioned in close proximity to a surface
55
of a disk
52
that is moving relative to the transducer in the direction of arrow
58
. The disk has a media layer
60
that has an easy axis of magnetization that is substantially perpendicular to the disk
22
surface. The disk also has a low-coercivity, high-permeability (“soft magnetic”) underlayer
62
that provides a path for magnetic flux, allowing the flux
64
written by the transducer to be directed substantially perpendicular to the disk surface. The transducer
50
includes a write pole
66
and a return pole
68
that are magnetically coupled by a magnetic layer
70
in the transducer and by the underlayer
60
to form a magnetic circuit, with the write pole
66
communicating a more concentrated flux
64
through the media
62
than the return pole
68
, for magnetizing the media adjacent the write pole.
FIG. 3
illustrates a prior art pattern of magnetization
70
of such a write pole
66
for a track such as track
30
where the transducer is skewed relative to the track. The write pole has a conventional rectangular area facing the media, which is reflected in the most recent magnetization
72
. Prior magnetizations written to the media, such as magnetization
71
, have edge effects or side writing
75
from the skew that may lead to errors in reading data.
SUMMARY OF THE INVENTION
In accordance with the present invention, write poles having a leading edge that is smaller than a trailing edge are disclosed, which can reduce erroneous writing for perpendicular recording systems. The write poles may have a trapezoidal shape when viewed from a direction of an associated media. The write poles may be incorporated in heads that also contain read elements such as magnetoresistive sensors, and may be employed with information storage systems such as disk drives.
REFERENCES:
patent: 4423450 (1983-12-01), Hamilton
patent: 4751598 (1988-06-01), Hamilton
patent: 4843507 (1989-06-01), Schewe et al.
patent: 4860139 (1989-08-01), Hamilton
patent: 4873599 (1989-10-01), Sueoka
patent: 4970615 (1990-11-01), Gau
patent: 4970616 (1990-11-01), Ramaswamy
patent: 5126232 (1992-06-01), Gau
patent: 5137750 (1992-08-01), Amin et al.
patent: 5453315 (1995-09-01), Hamilton et al.
patent: 5557488 (1996-09-01), Hamilton et al.
patent: 5615069 (1997-03-01), Slade et al.
patent: 5687046 (1997-11-01), Mathews
patent: 5737826 (1998-04-01), Slade et al.
patent: 5949625 (1999-09-01), Sato et al.
patent: 5995341 (1999-11-01), Tanaka et al.
patent: 5999380 (1999-12-01), Slade et al.
patent: 6054023 (2000-04-01), Chang et al.
patent: 6069775 (2000-05-01), Chang et al.
patent: 6163442 (2000-12-01), Gill et al.
patent: 6504675 (2003-01-01), Shukh et al.
patent: 6513228 (2003-02-01), Khizroev et al.
patent: 6687085 (2004-02-01), Minor et al.
patent: 6693768 (2004-02-01), Crue et al.
patent: 6697221 (2004-02-01), Sato et al.
patent: 6710973 (2004-03-01), Okada et al.
patent: 6721131 (2004-04-01), Litvinov et al.
U.S. Provisional application No. 60/175,860, Batra, filed Jan. 12, 2000.
U.S. Provisional application No. 60/206,872, Shukh et al., filed May 24, 2000.
IEEE Transactions on Magnetics article entitled “Off-Track Performance of Thin Film Single Pole Head For Perpendicular Double-Layered Media”, by H. Yamada et al., vol. 34, No. 4, Jul. 1998, pp. 1468-1470.
Chen Yingjian
Hiner Hugh Craig
Liu Francis
Shi Xizeng
Sin Kyusik
Lauer Mark
Silicon Edge Law Group LLP
Tupper R. S.
Western Digital (Fremont) Inc.
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