Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-03-23
2004-09-28
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06798615
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to perpendicular magnetic recording heads, and more particularly relates to a perpendicular recording head having a main write pole and multiple return poles which reduce or eliminate the flux antenna effect caused by stray magnetic fields.
BACKGROUND INFORMATION
Perpendicular magnetic recording systems have been developed for use in computer hard disk drives. A typical perpendicular recording head includes a trailing main pole, a leading return pole magnetically coupled to the main pole, and an electrically conductive magnetizing coil surrounding the main pole. The bottom of the return pole has a surface area greatly exceeding the surface area of the tip of the main pole. Conventional perpendicular recording media typically include a hard magnetic recording upperlayer and a soft magnetic underlayer which provide a flux path from the trailing write pole to the leading return pole of the writer.
To write to the magnetic recording media, the recording head is separated from the magnetic recording media by a distance known as the flying height. The magnetic recording media is moved past the recording head so that the recording head follows the tracks of the magnetic recording media, with the magnetic recording media first passing under the return pole and then passing under the main pole. Current is passed through the coil to create magnetic flux within the main pole. The magnetic flux passes from the main pole tip, through the hard magnetic recording track, into the soft underlayer, and across to the return pole.
The closed magnetic flux path provided by the trailing pole, soft underlayer and return pole increases efficiency of such conventional systems. The soft underlayer also effectively doubles the recording layer thickness through the effect of magnetic imaging. Furthermore, the soft underlayer advantageously increases vertical field gradients in the recording media through the magnetic imaging effect.
However, a problem associated with the use of soft underlayers is that such layers cause extreme sensitivity of the perpendicular recording system to stray magnetic fields. For example, stray fields of approximately 5 œ, e.g., from a voice coil motor, may be sufficient to cause data instability and to initiate random erasing of previously written information. This problem resulting from stray magnetic fields is known as the flux antenna effect.
The present invention has been developed in view of the foregoing.
SUMMARY OF THE INVENTION
An aspect of the present invention is to provide a perpendicular magnetic recording head comprising a main write pole and multiple return poles. The return poles substantially eliminate the flux antenna effect during operation of the recording head.
Another aspect of the present invention is to provide a perpendicular magnetic recording system comprising a perpendicular magnetic recording medium including a hard magnetic recording layer and a soft magnetic underlayer, and a perpendicular magnetic recording head positionable over the medium. The recording head comprises a main write pole, and multiple return poles.
A further aspect of the present invention is to provide a method of making poles of a perpendicular magnetic recording head. The method includes the steps of depositing a first return pole layer, depositing a main write pole layer over at least a portion of the first return pole layer, and depositing a second return pole layer over at least a portion of at least one of the first return pole layer and main write pole layer.
These and other aspects of the present invention will be more apparent from the following description.
REFERENCES:
patent: 3940797 (1976-02-01), Brock et al.
patent: 4317148 (1982-02-01), Chi
patent: 4423450 (1983-12-01), Hamilton
patent: 4438471 (1984-03-01), Oshiki et al.
patent: 4541026 (1985-09-01), Bonin et al.
patent: 4546398 (1985-10-01), Toda et al.
patent: 4575777 (1986-03-01), Hosokawa
patent: 4613918 (1986-09-01), Kanai et al.
patent: 4635153 (1987-01-01), Shimamura et al.
patent: 4649449 (1987-03-01), Sawada et al.
patent: 4725909 (1988-02-01), Kawai
patent: 4731157 (1988-03-01), Lazzari
patent: 4799115 (1989-01-01), Rogers et al.
patent: 4974110 (1990-11-01), Kanamine et al.
patent: 5003423 (1991-03-01), Imamura et al.
patent: 5073836 (1991-12-01), Gill et al.
patent: RE35212 (1996-04-01), Barnes et al.
patent: 5726839 (1998-03-01), Shinohara et al.
patent: 5738927 (1998-04-01), Nakamura et al.
patent: 5920449 (1999-07-01), Tagawa
patent: 6072669 (2000-06-01), Indeck
patent: 6111724 (2000-08-01), Santini
patent: 6134089 (2000-10-01), Barr et al.
patent: 6172848 (2001-01-01), Santini
patent: 6201670 (2001-03-01), Chang et al.
patent: 6278591 (2001-08-01), Chang et al.
patent: 6282056 (2001-08-01), Feng et al.
patent: 6574072 (2003-06-01), Batra
patent: 6646827 (2003-11-01), Khizroev et al.
patent: 6667848 (2003-12-01), Khizroev et al.
patent: 6721131 (2004-04-01), Litvinov et al.
patent: 2002/0131203 (2002-09-01), Litvinov et al.
patent: 0326904 (1989-08-01), None
patent: 54128719 (1979-10-01), None
patent: 5504734 (1980-01-01), None
patent: 55055420 (1980-04-01), None
patent: 55080818 (1980-06-01), None
patent: 56087218 (1981-07-01), None
patent: 57033421 (1982-02-01), None
patent: 59195311 (1984-11-01), None
patent: 59231720 (1984-12-01), None
patent: 60059515 (1985-05-01), None
patent: 60124014 (1985-07-01), None
S.H. Charap et al., “Thermal Stability of Recorded Information at High Densities,”IEEE Transactions on Magnetics, vol. 33, No. 1, Jan. 1997.
S.K. Khizroev et al., “Recording Heads with Track Widths Suitable for 100 Gbit/in2Density,”IEEE Transactions on Magnetics, vol. 35, No. 5, Sep. 1999.
Kazuyuki Ise et al., “High Writing-Sensitivity Single-Pole Head with Cusp-Field Coils,”IEEE Transactions on Magnetics, vol. 36, No. 5, Sep. 2000.
Kazuhiro Ouchi, “Recent Advancements in Perpendicular Magnetic Recording,”IEEE Transactions on Magnetics, vol. 37, No. 4, Jul. 2001.
Crue Billy Wayne
Khizroev Sakhrat
Litvinov Dmitri
Cao Allen
Pietragallo Bosick & Gordon
Seagate Technology LLC
Towner, Esq. Alan G.
LandOfFree
Perpendicular recording head with return poles which reduce... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Perpendicular recording head with return poles which reduce..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Perpendicular recording head with return poles which reduce... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3238300