Dynamic magnetic information storage or retrieval – Head – Gap spacer
Reexamination Certificate
2000-06-22
2002-11-05
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Gap spacer
Reexamination Certificate
active
06477002
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head used in a magnetic recording and reproducing apparatus such as a hard disk device and a magnetic tape device and having effects in high density recording, its manufacturing method, and a magnetic recording and reproducing apparatus mounting such thin film magnetic head.
2. Description of the Related Art
Hitherto, in a magnetic recording and reproducing apparatus, using an inductive type recording head, signals are recorded in a magnetic recording medium such as magnetic tape or magnetic disk, and the signals recorded in the magnetic recording medium are detected by using a magneto-resistive type (MR type) reproducing head.
In a magnetic recording and reproducing apparatus where high-density recording is required, the recording head and reproducing head are separately composed in order to optimize the recording efficiency and reproducing capacity. For example, in a hard disk device, a so-called thin film magnetic head integrally forming the inductive type recording head and MR type reproducing head or GMR type reproducing head as shown in FIG.
15
and
FIG. 16
is used.
A conventional thin film magnetic head is explained by referring to the drawings.
FIG. 15
is a front schematic view showing an air bearing surface (ABS) of a conventional thin film magnetic head with a recording medium, and
FIG. 16
is a top view of the conventional thin film magnetic head.
As shown in
FIG. 15
, a recording head
150
of this thin film magnetic head is composed of an upper magnetic core
151
, a recording gap
152
, a lower magnetic core
153
disposed adjacent the recording gap
152
, and a coil winding
164
(see FIG.
16
). The lower magnetic core
153
is also called a common shield because it has also a shielding function for the reproducing head. Herein, the width
154
of the portion confronting the common shield of the upper magnetic core
151
defines the mechanical recording track width.
A reproducing head
159
is composed of the common shield
153
and a lower magnetic shield
157
which are disposed adjacent a reproducing gap
158
, and an MR element
156
disposed between the shields
153
and
157
.
FIG. 17
shows a state of the recording magnetic field generated around the recording gap
152
, and a recording track width
171
is formed by the recording magnetic field. Due to the recording magnetic field leaking at both ends of the recording gap
152
, a recording region
171
where information is recorded on a magnetic recording medium spreads wider than the mechanical track width
172
of the magnetic core
151
. The region
173
in the recording magnetic field spreading wider than the mechanical track width is called a recording fringe. As mentioned above, the recording track width
171
is composed of the recording fringes
173
formed at both sides of the recording gap
152
, and a normal recording region
172
. On the other hand, the reproducing track width
155
(see
FIG. 15
) is generally formed smaller than the recording track width
171
in order to maintain an off-track margin.
The magnetic field strength of recording fringe
173
is weaker than that of the normal recording region
172
, and is different in the demagnetization field components in the recording medium as compared with the normal recording region
172
, and therefore the recording phases are different, and the noise components are larger.
An example of calculation of recording magnetic field occurring around the recording gap
152
in the composition in
FIG. 17
is shown in FIG.
18
. Herein, the x-direction is the gap width direction, the y-direction is the gap length direction, and the z-direction shows the intensity of the recording magnetic field. The swell of the recording magnetic field due to recording fringe is shown in parts
181
and
182
in the diagram.
In a conventional magnetic head, it has been attempted to join the butt ends of the recording gap in order to reduce the recording fringe in the width direction of the recording gap. For example, in a head for VTR, in order to eliminate butt end deviation, a trimming method wherein magnetic cores of the vicinity of the gap
191
are trimmed in shape
192
has been proposed as shown in
FIG. 19
(for example, Micro-Machining of Magnetic Metal Film Using Electro-discharge Technique. Y. Honma, International Conference of Micromechanics for Information, PP.318, 1997).
In the thin film magnetic head for HDD, a shape is proposed as shown in
FIG. 20
, in which a protrusion
203
is formed on a common shield
202
having a greater width than an upper magnetic core
201
by trimming. (For example, see Kiyono, “Effects of writing magnetic pole trimming in merge type MR head,” Lectures at 22nd Meeting of Japan Society of Applied Magnetism, p. 202, 1998.)
Generally, penetration distance of the magnetic field leaking from the recording gap is equal to or less than the ½ height of the gap width. Therefore, if attempted to reduce the fringe by a technique of joining the butt ends of the recording gap, the recording fringe in the recording magnetic field shown in
FIG. 17
expanded by the portion of gap width at maximum. Therefore, in order to record at higher density, it was required to reduce the recording track width further and curtail the recording fringe amount substantially at the same time.
SUMMARY OF THE INVENTION
The invention therefore provides a thin film magnetic head constituted by integrally forming an inductive recording head composed of a common shield serving commonly as upper magnetic core and lower magnetic core disposed adjacent a recording gap, and a coil winding, and a reproducing head composed of MR elements disposed between the common shield and lower magnetic shield, and the both magnetic shields, in which a shunt member made of a soft magnetic material is provided near the recording gap of the recording head.
This configuration presents a thin film magnetic head capable of suppressing leak magnetic field generated at the recording gap, decreasing the recording fringe substantially, narrowing the track in the recording head, and enhancing the recording track density, and a method of manufacturing the same.
REFERENCES:
patent: 5621595 (1997-04-01), Cohen
patent: 5959813 (1999-09-01), Watanabe et al.
patent: 6178065 (2001-01-01), Terunuma et al.
patent: 2-272731 (1990-11-01), None
Davis David
Dolan Jennifer M
McDermott & Will & Emery
LandOfFree
Thin film magnetic head for high density recording, a method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin film magnetic head for high density recording, a method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head for high density recording, a method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2968397