Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-06-26
2001-04-17
Heinz, A. J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06219213
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head for recording and/or reproducing a magnetic signal onto/from a magnetic recording medium and in particular to a magnetic head of yoke type having a magnetic circuit block.
2. Description of the Prior Art
Recently, in the magnetic recording medium such as a hard disc tends to increase its capacity, while increasing its recording density per unit surface. In such a situation, development of a magnetic head for recording and reproducing onto/from the recording medium having a large capacity.
Recently, as a magnetic head for such a magnetic recording medium having a large capacity, there has been used a magnetic head using a magnetoresistance effect element as a magneto-sensitive block (hereinafter, referred to as an MR head). As an MR head, there is a yoke type MR head as schematically shown in
FIG. 1
including yokes
102
A,
102
B, and
102
C and having a magnetoresistance effect element
100
and a non-magnetic body
101
. This yoke type MR head is constructed in such a manner that the magnetoresistance effect element
100
serving as a magneto-sensitive block will not slide along a magnetic recording medium, which enables to obtain an excellent durability. That is, in this yoke type MR head, the magnetoresistance effect element
100
serving as the magneto-sensitive block will not be brought into contact with the magnetic recording medium which may wear the magnetoresistance effect element
100
.
In this yoke type MR head, the yoke
102
A is arranged so as to oppose to the yoke
102
B through the non-magnetic body
102
, forming a magnetic gap. Through this magnetic gap, signal magnetic field from the magnetic recording medium is taken in. Moreover, in this yoke type MR head, the magnetic field take in causes a flow of magnetic flux through the magnetoresistance effect element
100
and yokes
102
A,
102
B, and
102
C, so as to constitute a magnetic circuit.
At this moment, in the magnetoresistance effect element
100
, its magnetization direction is changed by the magnetic flux flowing through the magnetic circuit, which in turn brings about a change of resistance value. In this yoke type head, a signal magnetic field is sensed by detecting the resistance change of the magnetoresistance effect element
100
. That is, this magnetoresistance effect element
100
does not detect a signal magnetic field directly but detects a magnetic field take in by the yokes
102
A,
102
B, and
102
C.
In the aforementioned yoke type MR head, the magnetoresistance effect element
100
is arranged between the yoke
102
B and the yoke
102
C. That is, in this yoke type MR head, a magnetic gap is formed between the yoke
102
B and the yoke
102
C which form the magnetic circuit, and the magnetoresistance effect element
100
is arranged in this magnetic gap.
When the magnetoresistance effect element
100
is formed in the magnetic gap between the yoke
102
B and the yoke
102
C, there will arise a large magnetic resistance at the bonding portion between the magnetoresistance effect element
100
and the yoke
102
B and the at the bonding portion between the magnetoresistance effect element
100
and the yoke
102
C. Accordingly, in the aforementioned yoke type MR head, the magnetic flux flowing through the magnetic circuit is reduced, which lowers the detection sensitivity of the magnetoresistance effect element
100
.
That is, in a conventional magnetic head, even if the magnetoresistance effect element
100
is used to cope with a high density recording, it is impossible to obtain a sufficient recording/reproduction characteristic. Thus, conventionally there has been no magnetic head which has a reduced size of magnetic circuit for a high density recording and has a sufficient recording/reproduction characteristic.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a magnetic head having a magnetic circuit of a reduced size to cope with a high density recording and having a sufficiently preferable recording/reproduction characteristic.
In order to achieve the aforementioned object, the magnetic head according to the present invention includes: a magnetic circuit block having at least partially a non-magnetic body through which magnetic bodies are opposed to each other, so as to constitute a magnetic path; and a magnetic tunnel element attached on the magnetic circuit block and including a first magnetic layer and a second magnetic layer which are layered via an insulation layer. This magnetic head is characterized in that a magnetic field from a magnetic recording medium is induced in the magnetic circuit block and the induced magnetic field changes a relative angle of magnetization of the first magnetic layer and/or the second magnetic layer with respect to the other magnetic layer.
In the magnetic head according to the aforementioned configuration having the aforementioned configuration, a magnetic field generated from a magnetic recording medium is induced to the magnetic circuit block. The magnetic circuit block is magnetized in a predetermined direction, applying a magnetic field to the magnetic tunnel element. Thus, in the magnetic tunnel element, the first magnetic layer and/or the second magnetic layer is magnetized in a predetermined direction, so as to have a predetermined relative angle between the magnetization of the first magnetic layer and that of the second magnetic layer. In this magnetic tunnel element, according to the relative angle of magnetization of the first magnetic layer with respect to the second magnetic layer, a tunnel current flowing between the first magnetic layer and the second magnetic layer changes its resistance value. Consequently, the magnetic head can detect the magnetic field from the magnetic recording medium by detecting the resistance value change of the tunnel current flowing between the first magnetic layer and the second magnetic layer.
REFERENCES:
patent: 5463516 (1995-10-01), Valet
patent: 5729410 (1998-03-01), Fontana
patent: 6137652 (2000-10-01), Ezaki
Goto Kazuo
Kumagai Seiji
Heinz A. J.
Sonnenschein Nath & Rosenthal
Sony Corporation
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