Inductor devices – Core forms casing
Reexamination Certificate
2000-08-21
2002-12-24
Donovan, Lincoln (Department: 2832)
Inductor devices
Core forms casing
C336S200000, C336S183000
Reexamination Certificate
active
06498553
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminated type inductor, more particularly, to a laminated type inductor used as a noise filter, and other suitable devices.
2. Description of the Related Art
Generally, when a laminated type inductor is used as a noise filter for a high-frequency signal line, low permeability material is used for a magnetic-substance layer. However, the laminated type inductor made of low permeability material has a problem in that it is easy to generate a link in the waveform of the high-frequency signal.
As a countermeasure, a conventional laminated type inductor
1
is shown in FIG.
5
. The laminated type inductor
1
is constructed such that a high permeability coil section
2
including magnetic-substance layers made of high permeability materials, and a low permeability coil section
3
including magnetic-substance layers made of low permeability materials are laminated and integrally fired. Coil conductors
4
-
6
in the high permeability coil section
2
and coil conductors
7
-
9
in the low permeability coil section
3
are electrically connected in series through via holes (not illustrated) to define a spiral coil L. One end (coil conductor
9
) of the spiral coil L is connected to an external electrode
11
. The other end (coil conductor
4
) thereof is connected to an external electrode
12
.
Moreover, a laminated type inductor
21
is also shown in
FIG. 6. A
laminated type inductor
21
is constructed such that a high permeability coil section
22
including magnetic-substance layers made of high permeability materials, a low permeability coil section
23
including magnetic-substance layers made of low permeability materials, and an intermediate section
24
made of a non-magnetic material which is disposed between the coil sections
23
and
24
are laminated and integrally fired. Coil conductors
25
-
28
arranged in the high permeability coil section
22
and coil conductors
29
-
32
arranged in the low permeability coil section
23
are electrically connected in series through via holes (not illustrated) to define a spiral coil L.
In the conventional laminated type inductors
1
and
21
, when the magnetic field H
1
generated in the high permeability coil sections
2
and
22
and the magnetic field H
2
generated in the low permeability coil sections
3
and
23
cause mutual interference, the noise suppressing effect is insufficient. To prevent the mutual interference of the magnetic fields H
1
and H
2
, the laminated type inductor
1
shown in
FIG. 5
has a large distance D between the coil conductors
4
-
6
of the high permeability coil section
2
, and the coil conductors
7
-
9
of the low permeability coil section
3
. However, as the distance D increases, the size of the laminated type inductor
1
also increases.
On the other hand, in the laminated type inductor
21
shown in
FIG. 6
the intermediate section
24
is located between the high permeability coil section
22
and the low permeability coil section
233
gv
to prevent the mutual interference of magnetic fields H
1
and H
2
. However, it is technically difficult to accomplish integrally baking both the magnetic material for the coil sections
22
and
23
, and the dielectric material for the intermediate section
24
, because the physical structure and the rate of heat-shrinking of both are substantially different. Thus, controlling the manufacturing processes is complicated.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a small-sized laminated inductor with a substantially simplified baking process.
According to preferred embodiments of the present invention, a laminated type inductor including a low permeability coil section in which magnetic layers made of a relatively low permeability material and coil conductors are laminated, and a high permeability coil section in which magnetic layers made of a relatively high permeability material and coil conductors are laminated, the low permeability coil section and the high permeability coil section are laminated such that the coil conductors of the low permeability coil section and the coil conductors of the high permeability coil section are electrically connected in series to define a spiral coil, and the winding direction of the coil conductors in the low permeability coil section and the winding direction of the coil conductors in the high permeability coil section are opposite to each other.
When the low permeability coil section and the high permeability coil section are bonded together, since both of them are made of magnetic materials without using a different material, bonding reliability is substantially improved.
Moreover, since the winding direction of the coil conductors in the low permeability coil section and the winding direction of the coil conductors in the high permeability coil section are arranged in the opposite direction, mutual interference of the magnetic field produced in the low permeability coil section and the magnetic field produced in the high permeability coil section is prevented.
Other features, elements, characteristics and advantages of the present invention will become apparent from the following description of preferred embodiments thereof with reference to the attached drawings.
REFERENCES:
patent: 5157576 (1992-10-01), Takaya et al.
patent: 2-82007 (1990-06-01), None
patent: 6-50311 (1994-07-01), None
patent: 9-7835 (1997-01-01), None
Tanaka Tadashi
Tokuda Hiromichi
Donovan Lincoln
Nguyen Tuyen T.
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