Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
1999-06-08
2001-07-17
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Coil
C360S236600
Reexamination Certificate
active
06262865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head provided in, for example, a magneto-optical disk device, and, more particularly, to a magnetic head which is thinner, which can be used to generate a magnetic field more efficiently, etc.
2. Description of the Related Art
FIG. 11
is a partial perspective view of a conventional magneto-optical recording magnetic head (or MO head).
FIG. 12
is an exploded perspective view of the core assembly of FIG.
11
.
The magnetic head
40
comprises a slider
41
and a core assembly
42
. The slider
41
is formed of a nonmagnetic ceramic material, such as calcium titanate (TiCaO
3
). The bottom surface of the slider
41
is the recording medium facing surface of the slider
41
. The top surface of the slider
41
is supported by a supporting member.
As shown in
FIG. 12
, a center core
43
of the core assembly
42
has a rectangular parallelepiped shape. Sides cores
44
and
44
are substantially L-shaped cores. One end of the center core
43
and one end of each of the side cores
44
are joined by nonmagnetic materials
45
and
45
at a magnetic gap G.
An electrically conductive coil
47
is wound on a bobbin
46
having a through hole
46
a
extending from the top surface to the bottom surface of the bobbin
46
. The center core
43
is inserted into the through hole
46
a
. A back core
48
is joined to the center core
43
and the side cores
44
and
44
, whereby the core assembly
42
is formed.
The magnetic head
40
of
FIG. 11
is a floating-type head. As shown in
FIG. 11
, a flexure
49
, being a thin leaf spring member, is bonded to the top surface
41
a
of the slider
41
. The magnetic head is rockably supported at one end of a gimbal through the flexure
49
.
As shown in
FIG. 12
, by winding the electrically conductive coil
47
on the bobbin
46
, and inserting the bobbin
46
with the electrically conductive coil
47
wound thereon onto the center core
43
, the coil
47
can be very easily installed on the center core
43
. However, this method of installing the coil
47
on the center core
43
gives rise to various problems. For example, a thin magnetic head cannot be produced, and it is difficult to increase the efficiency with which a magnetic field is generated.
As shown in
FIG. 12
, in order to install the electrically conductive coil
47
onto the center core
43
, the height h
1
of the bobbin
46
on which the coil
47
is wound needs to be at least equal to the length of the center core
43
received by the hole
46
a
. In addition, when the length, or the like, of the nonmagnetic materials
45
and
45
provided at one end of the center core
43
is considered, the center core
43
needs to be made long, making it difficult to make the entire magnetic head thin. When the coil
47
is formed of an electrically conductive wire, the number of windings and the winding method varies with heads, so that variations occur in the inductance or other wire properties. Further, in order to increase the efficiency with which the center core
43
supplies a magnetic field to a recording medium, the coil
47
needs to be brought as close as possible to the magnetic gap G. However, the structure of the conventional magnetic head makes it extremely difficult to bring the coil
47
close to the magnetic gap G.
FIG. 13
is a plan view of another conventional magnetic head, as seen from the side thereof opposing the recording medium.
Referring to
FIG. 13
, reference numeral
50
denotes a plate-shaped core formed of a magnetic material, like the center core
43
and the side cores
44
and
44
of FIG.
12
. The recording medium opposing surface of the core has a planar shape, with a coil
51
being directly formed spirally on the opposing surface. The thickness of the magnetic head depends only on the thickness of the core
50
and the thickness of the diametrical portion of the planar coil
51
. Therefore, this type of magnetic head is thinner than the magnetic head
40
of FIG.
11
. When an alternating current is supplied to the planar coil
51
of the magnetic head of
FIG. 13
, a magnetic field is generated from a center
52
of the planar coil
51
winding, so that a vertical magnetic field is supplied to a recording medium.
However, since this type of magnetic head does not have a protruding core at a portion thereof where a vertical magnetic field is generated, magnetic field lines generated from the winding center
52
cannot be concentrated, so that the strength of the vertical magnetic field supplied from the winding center
52
to the recording medium becomes very weak. When, in order to strengthen the vertical magnetic field, a large amount of electrical current is supplied to the planar coil
51
, heat is produced, so that this type of magnetic head is not a desirable type of magnetic head.
In the magnetic head of
FIG. 13
, the planar coil
51
is formed directly on the recording medium opposing surface of the plate-shaped core, making it difficult to form the recording medium opposing surface into a floating surface (ABS surface). In addition, when floating capability is reduced and the planar coil
51
is in an exposed state at the recording medium opposing surface cause, for example, dirt to move onto the magnetic head.
SUMMARY OF THE INVENTION
In order to overcome the above-described conventional problems, it is an object of the present invention to provide a magnetic head which, for example, is thin and which allows a magnetic field to be produced with greater efficiency.
To this end, according to one aspect of the present invention, there is provided a magnetic head, comprising:
a core protruding from a base towards a recording medium, the core being formed of a magnetic material;
a planar coil formed spirally on the base, with the core as center;
a cover provided on the planar coil such that an end surface of the protruding core is exposed and such that a surface of the cover is formed in a same plane as the end surface of the protruding core;
wherein an end, or a terminal, of the planar coil is exposed at a side portion of the base or the cover.
In a preferred form, the base may be formed of a magnetic material, and the base and the protruding core may be integrally formed.
According to another aspect of the present invention, there is provided a magnetic head comprising two cores protruding from a base towards a recording medium, the cores being formed of a magnetic material;
a planar coil formed spirally on the base, with the cores as centers;
a cover provided on the planar coil such that an end surface of each protruding core is exposed and such that a surface of the cover is formed in a same plane as the end surface of the protruding cores;
wherein the planar coil is formed around the two cores, with the sectional area of one of the cores being smaller than the sectional area of the other of the cores, and with the winding direction of the portion of the planar coil formed around the small sectional area core and the winding direction of the portion of the planar coil formed around the larger sectional area core being opposite each other.
In a preferred form, the planar coil may be a thin film coil. The thin film coil may be formed so as to have a single layer or a plurality of layers to increase the number of windings.
In another preferred form, the planar coil may be formed directly on the base. In still another preferred form, the planar coil may be formed directly on the back side of the cover.
According to still another aspect of the present invention, there is provided a magnetic head, comprising a core protruding from a base towards a recording medium, the core being formed of a magnetic material;
a planar coil formed spirally on the base, with the core as center;
a cover provided on the planar coil such that an end surface of the protruding core is exposed and such that a surface of the cover is formed in a same plane as the end surface of the protruding core;
wherein an end, or a terminal, of the planar coil is exposed at a side por
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Klimowicz William
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