Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
1999-06-04
2002-06-04
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235000
Reexamination Certificate
active
06400530
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a complex magnetic head and a method for manufacturing a magnetic head core of a complex magnetic head and, more particularly, to a complex magnetic head for use in a floppy disk drive (hereinafter referred to as FDD) in which a high recording density head core (hereinafter referred to as a first head core) and a low recording density head core (hereinafter referred to as a second head core) are combined in a unitary structure and a method for manufacturing a complex magnetic head core.
The magnetic head for use in an FDD includes a complex magnetic head in which two head cores of different recording densities are combined into a unitary structure. This is because there are two types of floppy disc (hereinafter referred to as FD) as a recording medium, i. e., a high density FDD of 120 Mbytes and a low density FDD of less than 2 Mbytes and different head cores are needed for writing and reading these two different types of FD with a common FDD unit.
FIG. 15
illustrates a complex magnetic head disclosed in Japanese Patent Laid-Open No. 63-103468, in which reference numeral
1
is a complex magnetic head,
2
is a first head core,
21
is a first RIW core,
22
is a first R/W gap,
23
is a first erase core and
24
is a first erase gap. Reference numeral
3
is a second head core,
31
is a second R/W core,
32
is a second R/W gap,
33
is a second erase core and
34
is a second erase gap. Reference numeral
4
is a slider.
In order to manufacture the complex magnetic head
1
, the first head core
2
and the second head core
3
are separately prepared. Then, the first head core
2
and the second head core
3
are bonded together with the slider
4
interposed therebetween. At this time, the first head core
2
, the second head core
3
and the slider
4
are bonded together with an appropriate positioning so that the first R/W gap
22
, the first erase gap
24
and the like have appropriate gap depths (not shown).
One example of a method for preparing a head core will now be described.
FIGS. 16
a
to
16
e
are views explaining the manufacturing method for the head core disclosed in Japanese Patent Laid-Open No. 3-263602. The head core manufactured by this method is different from the first head core
2
or the second head core
3
shown in
FIG. 15
in terms of configuration but is substantially the same in terms of its function. In the figures, reference numeral
40
is a first core material,
41
is a first magnetic base plate provided with first gap grooves
41
a and
42
is a non-magnetic base plate. Also, reference numeral
43
is a second core material,
44
is a second magnetic base plate provided with second gap grooves
44
a
and coil grooves
44
b
. Reference numeral
45
is a chip-shaped head core prepared by this process.
First, the first core material
40
of
FIG. 16
a
and the second core material
43
of
FIG. 16
b
are joined with their first gap grooves
41
a
and the second gap grooves
44
a
positioned in aligned opposition with each other so that a series of holes is formed between the first and second core materials
40
and
43
as shown in
FIG. 16
c
. These holes defined by the first and the second gap grooves
41
a
and
44
a
are then filled with a fused glass material (not shown). As illustrated in
FIG. 16
c
, the assembly is cut along dot-and-dash lines into the configuration illustrated in
FIG. 16
d
, which then is sliced along dot-and-dash lines shown in
FIG. 16
d
to obtain a head core
45
shown in
FIG. 16
e.
When the head core is to be manufactured by the above-described conventional process shown in
FIGS. 16
a
to
16
e
, a displacement can be easily generated between the first gap grooves
41
a
and the second gap grooves
44
a
when the first core material
40
and the second core material
43
are bonded and the track surfaces of the head core manufactured are often out of alignment. This misalignment may not cause any problem for the second head core for the low density FDD which has a track width of 125 &mgr;m, but can significantly affect the recording and reproducing operation of the high density FDD which has a track width of 8 &mgr;m. That is, when the first head core
2
is manufactured by the conventional process illustrated in
FIG. 16
, many of head cores manufactured have the above-mentioned fatal track misalignment, resulting in a low yield.
Upon manufacturing the complex magnetic head
1
shown in
FIG. 15
, the first head core
2
, the second head core
3
and the slider
4
are to be bonded to each other with an appropriate positioning so that the first R/W gap
22
, the first erase gap
24
and the like have appropriate gap depths (not shown), so that the fine positional adjustments which are complicated and difficult must be achieved, lowering the productivity of the magnetic head.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a complex magnetic head free from the above-discussed problems of the conventional design.
Another object of the present invention is to provide a complex magnetic head in which no track surface displacement are generated.
Another object of the present invention is to provide a complex magnetic head in which gap depth of the head core can be easily controlled.
A further object of the present invention is to provide a method for manufacturing a magnetic head core of a complex magnetic head free from the above-discussed problems of the conventional technique.
With the above objects in view, the present invention resides in a method for manufacturing a magnetic head core of a complex magnetic head, comprising the steps of binding a first core material of a U-shaped cross section and a second core material of a flat plate shape to form a tubular core material having two bonded portions between the first and second core materials. Then, a plurality of grooves are formed in the tubular core material across one of the bonded portions to form a plurality of track surfaces. The grooves are then filled with a fused glass material, and the other of the bonded portions is removed to form a substantially U-shaped core block having a plurality of track surfaces separated by the glass-filled grooves. The U-shaped core block is then sliced along each of the grooves to obtain a plurality of magnetic head cores.
The step of filling the grooves with the glass material may include the step of forming a chromium layer on surfaces of the plurality of grooves before filling the grooves with the glass material to expedite the fusion of the glass material. The chromium layer may have a thickness of from 50 &mgr;m to 300 &mgr;m.
The glass material may be a powder glass to expedite the fusion of the glass material or may be in a ladder shape and may be applied with the track surfaces received within its openings.
The step of filling the grooves with the glass material includes the step of placing a head support member on a side surface of the core materials and binding the head support member with the core materials by the fusion of a glass material, and wherein the step of cutting the U-shaped core block along each of the grooves into a plurality of magnetic head cores includes the step of cutting the head support member upon the cutting of the U-shaped core block to provide a head support for the head core.
A complex magnetic head of the present invention comprises a planar base reference plate for providing a reference position, a first head core provided at its side portion with a first support portion positioned with respect to the reference plate and having provided at its leg portion with a first space portion, a first coil portion accommodated within the first space portion, a second head core provided at its side portion with a second support portion positioned with respect to the reference plate and having provided at its leg portion with a second space portion, a second coil portion accommodated within the second space portion, and a holder disposed between the first head core and the second head core, havin
Handa Seiichi
Hibara Tatsunori
Ishii Hiromasa
Kasuga Yoshio
Kouhashi Masao
Birch Stewart Kolasch & Birch
Klimowicz William
Mitsubishi Denki K.K.
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