Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-03-16
2001-09-04
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S321000
Reexamination Certificate
active
06285531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head to be used in such as a magnetic disc unit, in particular, a magnetic head which uses a magneto-resistance effect head as a reproducing head.
2. Description of the Related Art
Accompanying recent high densification of magnetic recording density, a magnetic head utilizing magneto-resistance effect (referred to as MR element hereinafter) in which an electric resistance of a certain kind of magnetic thin film or a magnetic multi-layer film varies according to an external magnetic field is gathering attention as a reproducing head in a high recording density system. An MR head has a magneto-resistance effect element (MR element) in which an magneto-resistance effect film is used.
In a conventional magnetic disc unit, recording/reproducing operation is executed by levitating a magnetic head from a recording medium on a disc. Accompanying increase of a magnetic recording density, there is a tendency of lowering the levitation height of a magnetic head and a method of reading out information by gliding at a position more close to the medium is being tried.
However, when the recording density becomes 10 Gbpsi (Gbits/inch
2
) or more, due to spacing loss through levitation of a magnetic head, it becomes difficult to get an enough S/N ratio of the magnetic head, or, due to contact between the magnetic head and the recording medium, possible damage be ignored. Therefore, such a recording/reproducing method as that, by devising a structure of a contact type magnetic head, actively makes contact with the recording medium is being tried.
In a magnetic head utilizing an MR element too, the contact method is expected as a technology capable of responding to high recording density. However, if an MR element is disposed directly on an air bearing surface, there is a risk of the MR element being worn out. If the MR element is worn out, width in a length (depth) direction varies creating fluctuation in head output, further there is a possibility that the MR film itself disappears. For this, use of a so-called yoke type MR head in which, to an MR element disposed inside a head, a signal magnetic field is led by a magnetic yoke consisting of a pair of magnetic cores disposed oppositely through a magnetic gap, is being investigated.
FIG. 23
is a perspective view showing an outline structure of a conventional yoke type MR head and a relative position relationship between the yoke type MR head and a recording medium. In the figure, numeral
1
shows a magnetic yoke consisting of a pair of magnetic cores. On the side of an air bearing surface of the magnetic yoke
1
, a magnetic gap film
2
is interposed. An MR film
3
is disposed in such a manner that the MR film
3
is respectively magnetically coupled with a pair of magnetic cores constituting the magnetic yoke
1
. Though not shown in the figure, the magnetic yoke
1
is insulated from the MR film
3
. In the figure, numeral
4
is a pair of leads for supplying a sense current to the MR film
3
.
The magnetic yoke
1
can be used as a magnetic pole of a recording head. Therefore, it is being investigated to form a recording coil
5
, which supplies a recording magnetic flux to the magnetic yoke
1
, on the rear portion of the magnetic yoke
1
. Such a yoke type magnetic head can be used as a magnetic recording/reproducing separation type head.
In the yoke type MR head above described, the MR film
3
is an electromagnetic conversion portion and concurrently serves as a part of a magnetic circuit. In order to get a large output, it is required for magnetic resistance of the magnetic circuit as a whole to be reduced. In particular, the magnetic resistance is large at the MR film
3
and a neighboring area thereof. To transmit effectively a signal magnetic flux, which is led through the magnetic yoke
1
, to the MR film
3
, gap design between the magnetic yoke
1
and the MR film
3
becomes important. Primarily, to a degree an electric insulation can be secured, the yoke
1
and the MR film
3
are designed to be disposed as close as possible.
A yoke type MR head is expected as a head structure capable of responding to a contact recording/reproducing method. Further, it is expected as a head structure capable of easily responding to a magnetic recording/reproducing separation type head which concurrently uses a recording
However, according to the investigation of the present inventors, as shown in
FIG. 23
, when the MR film
3
and the recording coil
5
are formed in the same plane, there is a concern that a magnetic field generated by an electric current flowing the recording coil
5
affects badly the MR film
3
. This is considered to be a source of noise. Further, accompanying the high densification of the recording density, there is a risk of flowing in of a signal magnetic flux (shown in
FIG. 23
with dotted lines) on the MR film
3
from a neighboring track T′ as well as a recording track T to be traced. This is also considered to be a source of noise.
As shown in
FIG. 24
, there is also being discussed of a structure in which the magnetic yoke
1
is separated into a magnetic yoke
1
A for a reproducing head and a magnetic yoke
1
B for a recording head. In such a case, there is a concern of flowing in of a recording magnetic flux to a magnetic gap film
2
A of the magnetic yoke
1
A for a reproducing head from a magnetic gap film
2
B of the magnetic yoke
1
B for a recording head. This is also considered to be a source of noise. Besides, when a signal magnetic flux flows into a magnetic gap film
2
B of a magnetic yoke
1
B for a recording head from a magnetic gap film
2
A of a magnetic yoke
1
A for a reproducing head, there is a concern of recording fringe occurrence.
Thus, according to the investigation of the present inventors, in a magnetic head utilizing a magnetic yoke, there is a concern that a magnetic field, which occurs at the recording coil in the reproducing MR head, or a magnetic flux, which flows in from a neighboring track or the recording magnetic gap film, become sources of noise. Thereby, it is considered to cause a problem of inviting a deterioration of the reproducing sensitivity and the like. Besides, in a recording head, there is a concern that the magnetic flux flowing in from the reproducing magnetic gap film causes to occur the recording fringe.
SUMMARY OF THE INVENTION
Therefore, an objective of the present invention is to provide a magnetic head which enables to suppress decrease of reproducing sensitivity of a reproducing MR head due to noise occurrence and occurrence of recording fringe in a recording head, in particular, to provide a magnetic recording/reproducing separation type head which can suppress at the same time decrease of the reproducing sensitivity as well as the recording fringe.
A first magnetic head of the present invention comprises a pair of magnetic cores having an air bearing surface, a magnetic gap film interposed between the pair of magnetic cores on the side of the air bearing surface, at least one element selected from a magneto-resistance effect element in which a signal magnetic flux is led from a recording medium through a pair of magnetic cores and a recording coil which supplies a recording magnetic flux to the recording medium, and a ferromagnetic layer which is disposed on an extension of the film plane of the magnetic gap film and has a film plane having a perpendicular direction component with respect to the film plane of the magnetic gap film.
A second magnetic head of the present invention comprises at least pair of magnetic cores having an air bearing surface, a magnetic gap film interposed between the pair of magnetic cores on the side of the air bearing surface, a magneto-resistance effect element in which a signal magnetic flux is led from the recording medium through the pair of magnetic cores, wherein the magneto-resistance effect element is disposed along one main surface of the pair of magnetic cores, and a recording coil supplying a recording magnetic
Hori Akio
Ohsawa Yuichi
Sahashi Masashi
Yoda Hiroaki
Yoshikawa Masatoshi
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Renner Craig A.
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