Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2000-09-18
2002-11-12
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S223000, C336S232000
Reexamination Certificate
active
06480087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminated inductor array-having a plurality of inductors.
2. Description of the Related Art
A conventional laminated inductor array of the type shown in
FIG. 9
is known. The laminated inductor array
1
includes magnetic sheets
2
on the surface of which coil conductors
3
a
-
6
e
are provided. The coil conductors
3
a
-
3
e
are electrically connected in series through via holes
12
provided in the magnetic sheets
12
to constitute a spiral inductor L
1
. Similarly, coil conductors
4
a
-
4
e
,
5
a
-
5
e
, and
6
a
-
6
e
are electrically connected in series through via holes
12
provided in the magnetic sheets
12
to constitute spiral inductors L
2
, L
3
, and L
4
, respectively.
The magnetic sheets
2
are stacked on each other in order as shown in
FIG. 9
, and after magnetic cover sheets (not illustrated) having no conductor provided thereon, have been disposed on the top and bottom surfaces of the stacked magnetic sheets
2
, they are integrally sintered to form a laminated body
15
as shown in FIG.
10
. On the front and back surfaces of the laminated body
15
, external electrodes
21
a
-
24
a
and
21
b
-
24
b
of the inductors L
1
-L
4
are provided, respectively.
In the laminated inductor array
1
having the above-described construction, to provide a small-sized inductor array, when the inductors L
1
-L
4
are disposed close to each other inside the laminated body
15
, the magnetic path of each of the inductors L
1
-L
4
interferes with one another, and the mutual magnetic coupling between the inductors L
1
-L
4
becomes too large to disregard the coupling. As a result, the inductors L
1
-L
4
inside the laminated body
15
often have different values of inductance.
Generally, the spiral inductors L
1
and L
4
located adjacent the left and right end surfaces of the laminated body
15
have less inductance, because the magnetic paths are narrowed at the end surfaces. In particular, as in the spiral inductor L
4
, when the number of the coil conductors
6
b
,
6
c
, and
6
d
on the left side in
FIG. 11
is three and the number of the coil conductors
6
a
,
6
b
,
6
d
, and
6
e
on the right side in
FIG. 11
is four, on the side of the end surface of the laminated body
15
where the number of the coil conductors is greater, the inductance is less than where the number of coil conductors is fewer, as explained in the following and the inductances become different between the inductors L
1
and L
4
. That is, in each of the inductors L
1
-L
4
, the greater the number of the coil conductors, the larger the potential inductance is, and when the effective area of the magnetic path of coil conductors of a greater number as in the inductor L
4
is reduced, the inductance is further decreased.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a laminated inductor array including a plurality of inductors provided in a laminated body and which inductors have minimal variations in the inductance values thereof.
A laminated inductor array according to a preferred embodiment of the present invention includes a laminated body including a plurality of magnetic layers and a plurality of coil conductors provided thereon, a plurality of spiral inductors defined by the coil conductors which are electrically connected to one another and which are aligned in the laminated body, and external electrodes provided on the surfaces of the laminated body and connected to a lead-out end portion of each of the spiral inductors. In the laminated inductor array, in the direction of alignment of the spiral inductors, the number of the coil conductors on an end of the spiral inductor located at one end portion of the laminated body is equal to the number of coil conductors on an end of the spiral inductor located at the other end portion of the laminated body.
Further, a laminated inductor array according to another preferred embodiment of the present invention is constructed such that, in the direction of alignment of spiral inductors, at least a pattern of the coil conductor of the spiral inductor located at one end portion of the laminated body is symmetric about a central line with respect to a pattern of the coil conductor of the spiral inductor located at the other end portion of the laminated body.
Furthermore, a laminated inductor array according another preferred embodiment of the present invention is constructed such that, in the direction of alignment of spiral inductors, one lead-out portion of the respective spiral inductors located at one end portion and the other end portion of the laminated body respectively is led out from the middle of the respective spiral inductors.
Generally, the effective area of the magnetic path of two spiral inductors located at the end portions of a laminated body are reduced on the side of the end surfaces of the laminated body. However, because the number of the coil conductors on the end surface of a spiral conductor located at one end portion of a laminated body is equal to the number of the coil conductors on the end surface of a spiral conductor located at the other end portion of the laminated body, the decreased inductance value of the two spiral inductors located at the end portions of the laminated body is substantially equal and the inductance value of both inductors is therefore substantially equal.
Other features, elements, characteristics and advantages of preferred embodiments of the present invention will become apparent from the following detailed description of preferred embodiments thereof with reference to the attached drawings.
REFERENCES:
patent: 5578981 (1996-11-01), Tokuda
patent: 6191667 (2001-02-01), Takenaka et al.
patent: 11016738 (1999-01-01), None
patent: 11016760 (1999-01-01), None
Nishii Motoi
Nishinaga Yoshihiro
Oiwa Naotaka
Takeuchi Hiroyuki
Keating & Bennett LLP
Mai Anh
Murata Manufacturing Co. Ltd.
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