Magnetoresistive head including earth members

Details Magnetoresistive head including earth members Magnetoresistive head including earth members

2001-09-20

2003-12-30

Evans, Jefferson (Department: 2652)

Dynamic magnetic information storage or retrieval

Head

Magnetoresistive reproducing head

Reexamination Certificate

active

06671137

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a magnetoresistive head having a pair of shield layers disposed so as to sandwich a magnetoresistive film, and a multi-channel type magnetic head having a plurality of the magnetoresistive heads.
FIG. 6
shows a related magnetoresistive head
100
(hereinafter called as an MR head
100
). The MR head
100
is provided with a magnetoresistive element
101
(hereinafter called an MR element
101
) as a magnetic sensor element. The MR element
101
is configured by a magnetoresistive film
102
(hereinafter called an MR film
102
) which changes its resistance value with respect to a sense current in accordance with the change of magnetizing direction and a pair of electrodes
103
for supplying a sense current to the MR film
102
.
The MR head
100
is further provided with an upper shield layer
104
and a lower shield layer
105
which are disposed so as to sandwich the MR element
101
from the upper and lower direction, respectively. The upper shield layer
104
and the lower shield layer
105
sandwich the MR element through non-magnetic insulation films
106
. The non-magnetic insulation films
106
prevent a current flowing into the MR film
102
from being shunt and flowing into the upper shield layer
104
and the lower shield layer
105
.
Further, the MR head
100
includes an inductive head
107
as a recording element. In the inductive head
107
, an upper pole layer
109
is formed on the upper shield layer
104
through a gap film
108
. A coil portion
111
covered by an insulation film
110
is formed at a portion surrounded by the upper shield layer
104
and the upper pole layer
109
. That is, in the inductive head
107
, the upper shield layer
104
and the upper pole layer
109
constitute a magnetic core, whereby recording magnetic field is generated between the upper shield layer
104
and the upper pole layer
109
which are abutted to each other through the gap film
108
.
In the MR head
100
thus configured, the MR element
101
detects magnetic field generated from a magnetic recording medium to thereby reproduce information recorded on the magnetic recording medium. In the MR film
102
, the magnetizing direction changes by the magnetic field generated from the magnetic recording medium, so that a resistance value thereof with respect to the sense current is changed. In the MR head
100
, since the sense current is supplied so as to be constant, the change of the resistance value of the MR film
102
can be detected as the voltage change with respect to the sense current.
However, the MR head
100
can detect smaller magnetic field as compared with the case where the reproduction is performed by using the inductive head
107
, and the MR film
102
can be formed quite thinly by the thin film technique. Thus, a magnetic recording medium on which information is recorded at a high density can be reproduced by using the MR head. Accordingly, the MR heads
100
have been frequently employed in the hard disc driving apparatuses of computer apparatuses and so partially contribute to the high-density recording of the hard disc driving apparatuses.
In recent years, the MR heads
100
have been applied not only to the hard disc driving apparatuses but also to apparatuses for recording/reproducing a tape-shaped magnetic recording medium. In the latter case, information recorded on the tape-shaped magnetic recording medium is reproduced by using the MR head
100
. Thus, high-density recording can be promoted in the tape-shaped magnetic recording medium like the hard disc driving apparatus.
However, when the MR head
100
is applied to the recording/reproducing apparatus for a tape-shaped magnetic recording medium, the tape-shaped magnetic recording medium slides on and scrapes against the MR head
100
at a high speed to thereby cause static electricity, so that the MR film
102
is charged with static electricity. Since the MR element
101
is sandwiched between the upper shield layer
104
and the lower shield layer
105
through the non-magnetic insulation film
106
, the static electricity discharges due to voltage differences caused between the MR film
102
and the upper shield layer
104
and/or the lower shield layer
105
, whereby the MR element may be broken. When the MR element
101
is broken, the MR head can not be used any more.
In this manner, the MR head
100
has a problem that electrostatic breakage is likely occurred between the MR film
102
and the upper shield layer
104
and/or the lower shield layer
105
. In particular, this problem becomes more remarkable when the MR head
100
is used for a tape-shaped magnetic recording medium.
SUMMARY OF THE INVENTION
It is therefore an object of the invention is to provide an MR head which can surely prevent the occurrence of electrostatic breakage between an MR element and shield layers.
In order to achieve the above object, according to the present invention, there is provided a magnetoresistive head, comprising:
a first shield layer;
a first non-magnetic layer, formed on the first shield layer;
a magnetoresistive element, including a magnetoresistive film and an electrode portion both formed on the first non-magnetic layer;
a second non-magnetic layer, formed on the magnetoresistive element;
a second shield layer, formed on the second non-magnetic layer;
a non-magnetic metal layer, for electrically connecting the first shield layer and the second shield layer;
a first earth member, electrically connected to the electrode portion of the magnetoresistive element;
a second earth member, electrically connected to the first shield layer and the second shield layer; and
a third earth member, electrically connected to the first earth member and the second earth member.
In this configuration, since the first and the second earth members are coupled to the common third earth member, the electric potential of the magnetoresistive element and the shield layers are always made identical. Therefore, occurrence of the electrostatic breakage can be prevented so that recording and reproduction can be performed stably and reliably.
Preferably, the first, the second and the third earth members are made of a material having a higher resistance value than an entire resistance value of the magnetoresistive element.
In this configuration, a sense current supplied to the magnetoresistive film can be prevented from being shunt into the earth members.


REFERENCES:
patent: 5375022 (1994-12-01), Gill et al.
patent: 5465186 (1995-11-01), Bajorek et al.
patent: 5539598 (1996-07-01), Denison et al.
patent: 5805390 (1998-09-01), Takeura
patent: 5978181 (1999-11-01), Niijima et al.
patent: 6246553 (2001-06-01), Biskeborn
patent: 6288880 (2001-09-01), Hughbanks et al.
patent: 6415500 (2002-07-01), Han et al.
patent: 6470566 (2002-10-01), Hsiao et al.

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