Magnetoresistance-effect magnetic head

Details Magnetoresistance-effect magnetic head Magnetoresistance-effect magnetic head

2001-10-19

2004-01-13

Miller, Brian E. (Department: 2652)

Dynamic magnetic information storage or retrieval

Head

Magnetoresistive reproducing head

C360S319000

Reexamination Certificate

active

06678126

ABSTRACT:

RELATED APPLICATION DATA
The present application claims priority to Japanese Application(s) No(s). P2000-326120 filed Oct. 25, 2000, which application(s) is/are incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetoresistance-effect magnetic head that utilizes magnetoresistance effect to read signals magnetically recorded on a magnetic recording medium.
2. Description of the Related Art
Recording/reproducing apparatuses using a magnetic tape as a recording medium, such as a video tape recorder and a digital data recorder, are known. In such a recording/reproducing apparatus, the magnetic head writes and reads magnetic signals on and from the magnetic tape running in the apparatus, while kept in contact with the magnetic tape.
Recording/reproducing apparatuses of this type, which use a magnetic type have been modified, reducing the wavelength of signals to record data at high-density. To accomplish high-density recording, it is attempted to incorporate a magnetoresistance-effect magnetic head (hereinafter referred to as “MR head”) into recording/reproducing apparatuses that use a magnetic tape. This is because the magnetoresistance-effect magnetic head can reproduce signals with high efficiency.
The MR head has hitherto been used as a data-reproducing head, mainly in hard disc drives. The MR head for use as a data-reproducing head in a hard disc drive has a magnetoresistance-effect element (hereinafter referred to as “MR element”) that has magnetoresistance effect. The MR element is exposed at that surface of the MR head, which opposes the magnetic disc used as a recording medium in the disc drive. Thus exposed, the MR element can detect the signal magnetic field emanating from the magnetic disc.
The MR head is used as a data-reproducing head in recording/reproducing apparatuses using magnetic tape, too. In such a recording/reproducing apparatus, the MR head contacts the tape running while the MR head recording data on, or reproducing data from, the tape. The MR element of the MR head is exposed to the recording medium, i.e., the tape. As the tape runs, sliding on the MR element, the MR element gradually wears, changing the characteristics of the MR head gradually. Additionally, the operating reliability of the MR head decreases due to the noise made as the tape runs in sliding contact with the MR element. In view of this it is desired that an MR head for use in recording/reproducing apparatuses using magnetic tape should have an MR element that is not exposed to the magnetic tape, i.e., the recording medium.
A so-called “flux-guiding MR head” has been proposed as an MR head having an MR element not exposed to the recording medium. The flux-guiding MR head has a flux-guiding element that is made of, for example, soft magnetic thin film. The flux-guiding element is arranged, with its one end exposed to the recording medium. The flux-guiding element can therefore guide the signal magnetic field emanating from the recording medium, to the MR element.
FIG. 1
shows an example of a flux-guiding MR head
100
. As shown in
FIG. 1
, the flux-guiding MR head
100
comprises a pair of magnetic shield layers
101
and
102
, an MR element
104
, and a flux-guiding element
105
. The magnetic shield layers
101
and
102
are spaced apart. The layer
102
is positioned above the layer
101
, providing a gap
103
between the layers
101
and
102
. The MR element
104
and the flux-guiding element
105
are arranged in the gap
103
. The flux-guiding element
105
has one end positioned near the surface
100
a
of the MR head
100
, which faces the recording medium. Thus, this end of the flux-guiding element
105
is exposed at the surface
100
a
and opposes the recording medium. The MR element
104
is positioned at a longer distance from the surface
100
a
than the flux-guiding element
105
and is not exposed at the surface
100
a.
In the flux-guiding MR head
100
, the flux-guiding element
105
guides the signal magnetic field emanating from the magnetic recording medium, to the MR element
104
. The resistance of the MR element
104
varies in accordance with the signal magnetic field guided to the MR element
104
. The change in the resistance of the MR element
104
is detected as a voltage change, whereby a magnetic signal is read from the magnetic recording medium. As described above, the MR element
104
is not exposed at the surface
100
a
that faces the recording medium and does not contact the recording medium. The MR element
104
never wear or make noise while the recording medium, i.e., tape, is running. Hence, the MR head
100
can read the magnetic signal from the recording medium, without degrading the operating reliability.
In the flux-guiding MR head
100
of the structure described above, it is desired that the distance between the MR element
104
and the flux-guiding element
105
be as short as possible. The shorter the distance, the more efficiently the signal magnetic field can be transmitted from the flux-guiding element
105
to the MR element
104
. The hither the field-transmitting efficiency, the greater the magnitude of the output. If the MR element
104
and the flux-guiding element
105
contact, however, a part of the sense current to be supplied to the MR element
104
will flow to the flux-guiding element
105
. To prevent the sense current from flowing to the flux-guiding element
105
, it is necessary to space the MR element
104
and the flux-guiding element
105
apart from each other by a very short distance in the flux-guiding MR head
100
that has the structure specified above.
A gap is provided between the MR element
104
and the flux-guiding element
105
in a specific manner. As
FIG. 2
shows, an electrically insulating film
106
is formed, covering the MR element
104
, before the flux-guiding element
105
is formed. Once the flux-guiding element
105
is formed, that part of the film
106
, which is deposited on one side of the MR element
104
lies between the MR element
104
and the flux-guiding element
105
, spacing the MR element
104
from the flux-guiding element
105
. The gap between the elements
104
and
105
is therefore determined by the thickness of that part of the electrically insulating film
106
.
Here arises a problem. It is extremely difficult to control the thickness of the insulating film
106
deposited on said side of the MR element
104
, with high precision of nanometer order. In the flux-guiding MR head
100
of the structure described above, the operating efficiency of the MR element
104
will sharply decrease even if the distance between the MR element
104
and the flux-guiding element
105
changes a little. In view of this it is considered very difficult to manufacture, in a high yield, flux-guiding MR heads that can generates outputs of large magnitude.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing. An object of the invention is to provide a flux-guiding MR head in which the distance between the magnetoresistance-effect element and the flux-guiding element can be controlled with high precision and which can therefore generate a large output.
A magnetoresistance-effect element and a flux-guiding element can be spaced apart from each other by forming an electrically insulating film between them. It is relatively easy to control the thickness of the insulating film, as measured in the direction of depositing the insulating film. Hence, the distance between the magnetoresistance-effect element and the flux-guiding element can be controlled with high precision, only if the elements are formed at different levels, one overlapping the other.
In a magnetoresistance-effect magnetic head of the structure described above, the efficiency of transmitting a signal magnetic field from the flux-guiding element to the magnetoresistance-effect element greatly depends not only on the distance between these elements, but also on the distance for which the element

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