Wire-wound chip inductor

Details Wire-wound chip inductor Wire-wound chip inductor

1998-10-01

2001-06-19

Mai, Anh (Department: 2832)

Inductor devices

Winding formed of plural coils

Coil supports or spacers

C336S096000, C336S090000

Reexamination Certificate

active

06249203

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wire-wound chip inductor, and more particularly, to a wire-wound chip inductor in which a magnetic plate for increasing inductance is attached to a member for holding a wire.
2. Description of the Related Art
FIGS. 7 and 8
show a first example of a conventional wire-wound chip inductor.
A wire-wound chip inductor
1
shown in
FIGS. 7 and 8
comprises a wire holding member
6
having a core portion
3
with a wire
2
wound therearound, and flange portions
4
and
5
projecting from both ends of the core portion
3
in the axial direction, and a magnetic plate
7
attached to the wire holding member
6
to connect the flange portions
4
and
5
thereto.
The above elements of the wire-wound chip inductor
1
have respective widths extending in the same direction, which direction intersects the axial direction of the core portion
3
. Specifically, the outer periphery of the wire
2
has a width W
1
, the core portion
3
has a width W
2
, the flange portions
4
and
5
have a width W
3
, and the magnetic plate
7
has a width W
4
, as shown in
FIGS. 7 and 8
.
The width W
2
of the core portion
3
, the width W
3
of the flange portions
4
and
5
, and the width W
4
of the magnetic plate
7
are equal to each other. Therefore, the width W
1
of the outer form of the wire
2
is larger than these widths W
2
, W
3
, and W
4
.
FIGS. 9 and 10
show a second example of a conventional wire-wound chip inductor.
Similarly to the conventional wire-wound chip inductor
1
described above, a wire-wound chip inductor
11
shown in
FIGS. 9 and 10
comprises a wire
12
, a core portion
13
, flange portions
14
and
15
, a wire holding member
16
, and a magnetic plate
17
. The outer periphery of the wire
12
has a width W
1
, the core portion
13
has a width W
2
, the flange portions
14
and
15
have a width W
3
, and the magnetic plate
17
has a width W
4
.
While the width W
3
of the flange portions
14
and
15
and the width W
4
of the magnetic plate
17
are equal to each other in the wire-wound chip inductor
11
, the width W
2
of the core portion
13
is smaller than the width W
3
of the flange portions
14
and
15
, which is different from the wire-wound chip inductor
1
described above. Therefore, the width W
1
of the outer periphery of the wire
12
can be made smaller than the width W
3
of the flange portions
14
and
15
and the width W
4
of the magnetic plate
17
.
In the wire-wound chip inductor
1
shown in
FIGS. 7 and 8
, as mentioned above, the width W
2
of the core portion
3
, the width W
3
of the flange portions
4
and
5
, and the width W
4
of the magnetic plate
7
are equal. Therefore, the widths W
2
to W
4
define the outer periphery of the entire wire-wound chip inductor
1
. In other words, the width W
2
of the core portion
3
is equal to the outermost width of the wire-wound chip inductor
1
. When the width W
2
of the core portion
3
is large enough to be equal to the outermost width of the wire-wound chip inductor
1
, however, the length of one turn of the wire
2
increases, and a relatively large amount of stray capacitance thereby arises between adjacent portions of the wire
2
. This deteriorates the characteristics at high frequencies.
Moreover, since the width W
1
of the outer periphery of the wire
2
is larger than the width W
3
of the flange portions
4
and
5
or the width W
4
of the magnetic plate
7
, when the wire-wound chip inductor
1
is handled via a chuck or the like in mounting or in other situations, the wire
2
is prone to be scratched. For this reason, an insulating coating on the wire
2
may be undesirably stripped or the wire
2
may be broken.
On the other hand, according to the wire-wound chip inductor
11
shown in
FIGS. 9 and 10
, since the width W
2
of the core portion
13
is smaller than the width W
3
of the flange portions
14
and
15
, namely, the outermost width of the wire-wound chip inductor
11
, as mentioned above, the stray capacitance between adjacent portions of wire can be reduced. In addition, since the width W
1
of the outer periphery of the wire
12
can be made smaller than the width W
3
of the flange portions
14
and
15
or the width W
4
of the magnetic plate
17
, it is possible to solve the problem of the wire
12
being scratched during handling of the wire-wound chip inductor
11
.
In the wire-wound chip inductor
11
, however, since the width W
2
of the core portion
13
is smaller than the width W
3
of the flange portions
14
and
15
, the process of forming the wire holding member
16
including the core portion
13
and the flange portions
14
and
15
is complicated, which increases the manufacturing cost.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, the preferred embodiments of the present invention provide a wire-wound chip inductor that is constructed to avoid damage to the wire, stray capacitance and increased manufacturing costs experienced with conventional inductors.
According to a preferred embodiment of the present invention, there is provided a wire-wound chip inductor including a wire holding member having a core portion with a wire wound therearound and flange portions extending from both ends of the core portion in an axial direction, and a magnetic plate attached to the wire holding member to connect the flange portions, wherein an outer periphery of the wire, the core portion, the flange portions, and the magnetic plate have respective widths measured in a common direction.
In order to solve the problems experienced by conventional devices as described above, the widths of the elements of the wire-wound chip inductor have the following relationships.
More specifically, the width of the core portion and the width of the flange portions are substantially equal to each other, and the width of the magnetic plate is larger than the widths of the core portion and the flange portions.
Preferably, the width of the magnetic plate is larger than the width of the outer periphery of the wire.
Also, it is preferred that the magnetic plate has a pair of side wall portions extending from both widthwise ends thereof so as to sandwich the flange portions. More preferably, the pair of side wall portions extend such that they cover the wire.
Further objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the attached drawings.


REFERENCES:
patent: 4586016 (1986-04-01), Rilly et al.
patent: 4595901 (1986-06-01), Yahagi
patent: 5764126 (1998-06-01), Kanetaka et al.
patent: 5831505 (1997-09-01), Yamaguchi et al.
patent: 5844459 (1997-09-01), Larsen

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