Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-06-02
2001-10-02
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06297930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a magnetic head for floppy disc drive.
2. Background of Related Art
In general, since a FDD (floppy disc drive) is installed within a personal computer, the magnetic head of the FDD is likely to generate a reading error due to an electromagnetic noise from a CTR, a switching source and such. Then, in order to avoid such a reading error, it is a general countermeasure to shield the magnetic head with a magnetic material having a high permeability such as permalloy or ferrite (hereinafter referred this general magnetic head to as “conventional example 1”).
Now, recently in a note-type of personal computer (note personal computer) and such low-profile FDD having half-inch thickness is used. In this type, it has been difficult to shield the magnetic head with the material having a high permeability such as permalloy or ferrite. As a countermeasure to that, there is what is disclosed in the patent laid-open No. Hei 7-235013 (hereinafter referred to as “conventional example 2”).
The magnetic head
1
of the conventional example 2 comprises roughly, as shown in
FIG. 5
, a front chip core
2
having a read/write gap G
1
and an erasing gap G
2
, a first slider
4
a
and a second slider
4
b
which are made of a non-magnetic material (not shown) and form the front core
3
while being formed in unit with the front chip core
2
across the front chip core
2
, each side of which slides (upper in
FIG. 5
) on a magnet recording medium (not shown), a back yoke
5
which is made of a magnetic material having a high permeability such as permalloy or ferrite and contacts to the other side of the front core
3
and a read/write core
6
and an erasing coil
7
later mentioned respectively.
The back yoke
5
comprises a hollow square pillar-like outer body
8
whose tip end contacts to the afore-mentioned front core
3
, a block body
40
comprising a bottom portion
9
formed at the proximal side of the outer body
8
and similarly shaped three leg portions
10
a
,
10
b
and
10
c
(hereinafter referred to as “the first, second and third leg portion” viewing from right to left direction in
FIG. 5
) which stand upright on the bottom portion
9
in juxtaposing manner, each tip ends of which contacts to the afore-mentioned front chip core
2
to form a closed magnetic circuit (not shown) together with the front chip core
2
and afore-mentioned bottom portion
9
.
The outer body
8
is of approximately a hollow square pillar shape formed by connecting two opposing short side portions (hereinafter referred to as “first short side portion
8
11
” positioned right below in FIG.
5
and “second short side portion
8
12
” positioned left upper in
FIG. 5
) and two opposing long side portions (hereinafter referred to as “first long side portion
8
21
” right upper in FIG.
5
and “second long side portion
8
22
” left below in FIG.
5
), and between the first short side portion
8
11
and the first leg portion
10
a
and between the second short side portion
8
12
and the third leg portion
10
c
, a window
11
for a lead wire is formed. From the window
11
for lead wire, a lead
6
a
of the read/write coil
6
and a lead
7
a
of the erasing coil
7
are drawn out and connected to outer connecting terminals of a not shown FPC (flexible printed circuit board) etc.
The first and third leg portions
10
a
and
10
c
are inserted in the afore-mentioned read/write coil
6
and the erasing coil
7
.
In the magnetic head
1
of this conventional example 2, the back yoke
5
is made of magnetic material having a high permeability such as Mn—Zn ferrite, the outer body
8
and the bottom portion
9
function as a magnetic shield. And, in this case, since the back yoke
5
provided on the magnetic head
1
functions as a magnetic shield, a problem of the difficulty of the magnetic shielding generated in the case where the magnetic shield is carried out in a low profile FDD in the conventional example 1 is planned to be improved.
Now, in the conventional example 2, although that is the type in which the coils are of lead wire, it is thinkable, in place of the coil to be used in the conventional example 2, to use a bobbin type of coil with terminals (hereinafter referred to as “bobbin coil with terminals”) which is formed in such a manner as, as a coil, a bobbin made of a high heat resistance resin such as LPC and metal terminals are molded in a unit and with such bobbin wirings are coupled. In this case, in order to accommodate a terminal stand for the bobbin coil with terminals, the outer body is necessary to make large, for that reason, it has been difficult to miniaturize the magnetic head.
Further, in the back yoke
5
of the conventional example 2, as well as in manufacturing a ceramic, it is formed by molding a powder of Mn—Zn ferrite and such and a binder to a given shape with a mold, then is adapted to be sintered at a high temperature while burning out the binder and solidifying the powder simultaneously. Accordingly, if the leg portions (
10
a
,
10
b
and
10
c
) are made slimmer, there is anxiety that the leg portions are suffered from being bent or generating any crack. For that reason, in the conventional example 2, it has been difficult to make the leg portions slimmer which is led to miniaturize the apparatus as a whole.
Against such problem as bending or generating of crack on the leg portions is generated after sintering, there is one magnetic head in which the leg portions are made slimmer by a post-machining after sintering. Such an example is illustrated in Japanese patent laid-open publication No. Hei 10-40525 (hereinafter referred to as “conventional example 3).
The magnetic head
1
of the conventional example 3 comprises, as shown in
FIGS. 6 and 7
, a front core
3
which consists of a slider
4
and a front chip core
2
to be inserted in a hole
12
formed in the slider
4
and a back yoke
5
made of magnetic material having high permeability which is manufactured showing as follows.
The back yoke
5
is different, compared with the one of the conventional example 2, in that it has no window
11
for the lead on the bottom portion
9
, that on the second long side portion
8
22
the first, second and third projections
13
a
,
13
b
and
13
c
which extend to the first, second and third leg portions
10
a
,
10
b
and
10
c
respectively are formed and that the first and second short side portions
8
11
and
8
12
are provided with cut outs
14
respectively.
And, in this back yoke
5
is, at the time of being powder-molding and sintered, as shown in a dotted line
15
in
FIG. 6
, the first, second and third leg portions
10
a
,
10
b
and
10
c
are connected to the outer body
8
(the first, second and third projections
13
a
,
13
b
and
13
c
), and by a post-machining such as cutting for grooving, the portions circled with the dotted line
15
in
FIG. 6
are removed to separate the first, second and third leg portions
10
a
,
10
b
and
10
c
into a given width (thickness). Due to this cutting for grooving, the cut out
14
is formed on the first and second short side portions
8
11
and
8
12
. Through the cut out
14
, the lead
6
a
of the read/write coil
6
and the lead
7
a
of the erasing coil
7
are drawn out.
In the magnetic head
1
of the conventional example 3, the first, second and third leg portions
10
a
,
10
b
and
10
c
are, at the time of molding and sintering, connected to the outer body
8
and which prevent the leg portions
10
a
,
10
b
and
10
c
from being bent and being suffered from generating cracks.
However, in the above mentioned magnetic head
1
of the conventional example 3, when machining the first, second and third leg portions
10
a
,
10
b
and
10
c
into the given thickness, simultaneously on the outer body
8
the cut out
14
is formed, which happens to cause to bring about easily entering of outer noises through this cut out
14
.
Further, since the magnetic head
1
of the conventional example 3 is not provided with the bobbin coil with termi
Egawa Motoji
Kawashima Satoshi
Klimowicz William
Minebea Co. Ltd.
Oliff & Berridg,e PLC
Tianjie Chen
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