Dynamic magnetic information storage or retrieval – Record copying – Contact transfer
Reexamination Certificate
2001-10-23
2004-06-08
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
Record copying
Contact transfer
C360S066000, C361S149000
Reexamination Certificate
active
06747823
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for controlling magnetic recording in a magnetic recording medium, and a control device for magnetic recording, which can be used in particular with magnetic transfer technology for recording magnetization in perpendicular to the recording surface of the magnetic recording medium (the so-called perpendicular magnetic recording medium).
BACKGROUND OF THE INVENTION
A first example of a conventional magnetic transfer technology will be explained with reference to FIG.
15
(
a
) through FIG.
16
(
b
), which explain the principle of magnetic transfer technology which performs magnetic transfer onto the recording surface of a magnetic recording medium. FIG.
15
(
a
) is a cross-sectional view for explaining the initial magnetization of the so-called longitudinal magnetic recording medium, in which the magnetization thereof is parallel to the recording surface thereof. FIG.
15
(
b
) is another cross-sectional view for explaining the transfer magnetization of the longitudinal magnetic recording medium.
As shown in FIG.
15
(
a
), a magnetic recording disc
2
is positioned, as a longitudinal magnetic recording medium on a rotatable spindle stage
6
. A ring head
3
, including a magnet
3
a
and yokes
3
b
, is positioned at a position spaced apart for a distance Di in the upward direction from the recording surface of the magnetic recording disc
2
. Further, a master disc
5
having a plurality of soft magnetic patterns
5
a
is placed above the recording surface of the magnetic recording disc
2
. The ring head
3
generates a magnetic field in parallel to the circumferential direction of the magnetic recording disc
2
(that is, the parallel direction X). The direction of the magnetic field applied in the initial magnetization process and the direction of the magnetic field applied in the transfer magnetization process are opposite to each other.
For recording onto the longitudinal magnetic recording medium, first the magnetic recording medium is magnetized, as shown in FIG.
15
(
a
), in one direction within the recording surface of the magnetic recording medium using the ring head
3
(initial magnetization). Then, as shown in FIG.
15
(
b
), the ring head
3
is made to approach the magnetic recording disc
2
from the distance Di to the distance Dp, and a magnetic field, in the direction opposite the initial magnetization, is applied to the master disc
5
and magnetic recording disc
2
, which are in close contact with each other.
The magnetic field generated by the ring head
3
cannot reverse the initial magnetization of the recording medium, since the magnetic field localizes to the soft magnetic patterns
5
a
with high magnetic permeability. However, the magnetic field generated by the ring head
3
causes a leakage magnetic field in the portions of the magnetic recording medium not facing to any soft magnetic layer, and the leakage magnetic field reverses the initial magnetization of the magnetic recording medium. In this way, the soft magnetic pattern
5
a
of the master disc
5
is recorded as a magnetization pattern, the direction thereof is opposite to the direction of the initial magnetization in the longitudinal direction (that is, the parallel direction X). Due to the principle explained above, it is necessary that the direction of the applied magnetic field applied in the initial magnetization process and the direction of the applied magnetic field applied in the transfer magnetization process for longitudinal magnetic recording media be opposite to each other.
FIG.
16
(
a
) is a cross-sectional view for explaining the initial magnetization of the so-called perpendicular magnetic recording medium, in which the magnetization thereof is perpendicular to (in the perpendicular direction Y of) the recording surface thereof. FIG.
16
(
b
) is another cross-sectional view for explaining the transfer magnetization of the perpendicular magnetic recording medium. In the method of magnetic transfer to the perpendicular magnetic recording media, the direction of the applied magnetic field merely changes from the foregoing parallel direction X to the perpendicular direction Y. The direction of the applied magnetic field applied in initial magnetization and the direction of the applied magnetic field applied in transfer magnetization are opposite to each other. Further, due to a principle similar to the principle of the method of magnetic transfer to the longitudinal magnetic recording medium, it is necessary that the directions of the applied magnetic fields applied in the initial magnetization process and in the transfer magnetization process be opposite to each other.
A second example of the conventional art is explained with reference to FIG.
17
(
a
) through FIG.
18
(
b
). FIG.
17
(
a
) is a cross-sectional view for explaining the process of initial magnetization of the magnetic recording disc
2
. FIG.
17
(
b
) is another cross-sectional view for explaining the process of initial magnetization of the magnetic recording disc
2
.
In FIG.
17
(
a
), two single-pole heads (permanent magnets)
1
are aligned in perpendicular to (in the perpendicular direction Y of) the magnetic recording disc
2
and positioned symmetrically with respect to the magnetic recording disc
2
. The magnetic recording disc
2
, vacuum-chucked to the spindle stage
6
, is inserted such that the surface of the magnetic recording disc
2
, on which magnetic transfer is performed, coincides with the symmetry plane
0
spaced apart for an equal distance D from each of the magnetic poles of the two single-pole heads
1
. The magnitude of the perpendicular component of the magnetic field created in the symmetry plane by the two single-pole heads
1
is several Oe, which is substantially small compared with the coercive force Hc of the magnetic recording media currently in use (around 3000 Oe). The distance D at this stage is from 5 to 10 cm.
In FIG.
17
(
b
), the pair of single-pole heads
1
which are spaced apart from the magnetic recording medium for the distance D in FIG.
17
(
a
) are made to approach the recording medium, while maintaining a symmetrical arrangement with respect to the symmetry plane at which the recording surface of the recording medium is positioned, until the distance to the recording medium is Di. Then, the entire surface of the magnetic recording disc
2
is magnetized in a single direction (perpendicular to the symmetry plane) by rotating the spindle stage
6
. At this stage, the distance Di is from 2 mm to 3 mm, and the magnitude of the perpendicular component (perpendicular to the recording surface) of the magnetic field applied to the magnetic recording disc
2
is from 5000 to 6000 Oe.
FIG.
18
(
a
) is a cross-sectional view for explaining the process of transfer magnetization of the magnetic recording medium
2
. FIG.
18
(
b
) is another cross-sectional view for explaining the process of transfer magnetization of the magnetic recording medium
2
. In FIG.
18
(
a
), the magnetic recording disc
2
vacuum-chucked to a spindle stage
6
is inserted between two ring heads
3
, such that the surface, on which magnetic transfer is performed, of the magnetic recording disc
2
coincides with the symmetry plane
0
which is spaced apart for an equal distance D from the gaps of the two symmetrically positioned ring heads (permanent magnets)
3
. Then, a master disc
5
is placed in close contact with the magnetic recording disc
2
. At this stage, since the magnitude of the perpendicular component or of the parallel component of the magnetic field created at the symmetry plane by the two ring heads
3
is several Oe, which is small compared with the coercive force Hc of the magnetic recording media currently in use (around 3000 Oe), magnetic transfer is not conducted yet. The distance D at this stage is in the range between 5 and 10 cm like that shown in FIG.
17
(
a
).
In FIG.
18
(
a
), the pair of ring heads
3
, spaced apart for the distance D from the magnetic recording medium, are made to approach the magn
Saito Akira
Sato Kiminori
Yonezawa Eiichi
Faber Alan T.
Fuji Electric & Co., Ltd.
Rossi & Associates
LandOfFree
Method of demagnetizing and transferring magnetization in a... 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 of demagnetizing and transferring magnetization in a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of demagnetizing and transferring magnetization in a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3351432