Information
-
Patent Grant
-
6249203
-
Patent Number
6,249,203
-
Date Filed
Thursday, October 1, 199825 years ago
-
Date Issued
Tuesday, June 19, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
A wire-wound chip inductor includes 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 the axial direction, and a magnetic plate attached to the wire holding member to connect the flange portions. 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 form of the wire, and the magnetic plate has a pair of side wall portions extending from both widthwise ends thereof so as to sandwich the flange portions.
Description
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.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a perspective view separately showing a wire holding member and a magnetic plate of a wire-wound chip inductor according to a first preferred embodiment of the present invention;
FIG. 2
is a cross-sectional view of a wire-wound chip inductor including the wire holding member and the magnetic plate shown in
FIG. 1
;
FIG. 3
is a perspective view separately showing a wire holding member and a magnetic plate of a wire-wound chip inductor according to a second preferred embodiment of the present invention;
FIG. 4
is a cross-sectional view of a wire-wound chip inductor including the wire holding member and the magnetic plate shown in
FIG. 3
;
FIG. 5
is a perspective view separately showing a wire holding member and a magnetic plate of a wire-wound chip inductor according to a third preferred embodiment of the present invention;
FIG. 6
is a cross-sectional view of a wire-wound chip inductor including the wire holding member and the magnetic plate shown in
FIG. 5
;
FIG. 7
is a perspective view separately showing a wire holding member and a magnetic plate of a first example of a conventional wire-wound chip inductor;
FIG. 8
is a cross-sectional view of a first example of a conventional wire-wound chip inductor including the wire holding member and the magnetic plate shown in
FIG. 7
;
FIG. 9
is a perspective view separately showing a wire holding member and a magnetic plate of a second example of a conventional wire-wound chip inductor; and
FIG. 10
is a cross-sectional view of a second example of a wire-wound chip inductor including the wire holding member and the magnetic plate shown in FIG.
9
.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIGS. 1 and 2
show a wire-wound chip inductor according to a first preferred embodiment of the present invention.
Similar to the conventional wire-wound chip inductors
1
and
11
described with reference to
FIGS. 7
to
10
, a wire-wound chip inductor
21
shown in
FIGS. 1 and 2
comprises a wire holding member
26
having a core portion
23
with a wire
22
wound therearound, and flange portions
24
and
25
projecting from both ends of the core portion
23
in the axial direction, and a magnetic plate
27
attached to the wire holding member
26
to connect the flange portions
24
and
25
.
While the wire holding member
26
of
FIG. 1
is preferably made of an electrical insulating material such as a resin, the wire holding member
26
may also be made of a magnetic material in order to further increase the inductance. The magnetic plate
27
is constructed to form a closed magnetic path in the wire-wound chip inductor
21
to thereby yield a significantly larger inductance. The magnetic plate
27
is preferably made of a magnetic material such as ferrite, and fixed to the flange portions
24
and
25
via, for example, a thermosetting adhesive. At the lower ends of the flange portions
24
and
25
, for example, terminal electrodes, which are not shown, are provided to function as terminals in mounting the wire-wound chip inductor
21
on a circuit substrate while connecting ends of the wire
22
thereto.
The elements of the wire-wound chip inductor
21
have respective widths that are measured in the same direction, which direction intersects the axial direction of the core portion
23
. That is, the outer periphery of the wire
22
has a width W
1
, the core portion
23
has a width W
2
, the flange portions
24
and
25
have a width W
3
, and the magnetic plate
27
has a width W
4
.
Regarding these widths W
1
to W
4
in the wire-wound chip inductor
21
, the width W
2
of the core portion
23
and the width W
3
of the flange portions
24
and
25
are preferably substantially equal, and the width W
4
of the magnetic plate
27
is larger than the width W
2
of the core portion
23
and the width W
3
of the flange portions
24
and
25
. Preferably, the width W
4
of the magnetic plate
27
is larger than the width W
1
of the outer periphery of the wire
22
.
The magnetic plate
27
extends downwardly from both widthwise ends thereof to form a pair of side wall portions
28
and
29
which are arranged so as to sandwich the flange portions
24
and
25
.
According to such a wire-wound chip inductor
21
, the width W
4
of the magnetic plate
27
defines an outer periphery of the entire wire-wound chip inductor
21
. Since the width W
2
of the core portion
23
is smaller than that of the outer periphery of the wire-wound chip inductor
21
, it is possible to reduce the stray capacitance generated between adjacent portions of the wire
22
.
As mentioned above, while the width W
2
of the core portion
23
is made small, it is set to be substantially equal to the width W
3
of the flange portions
24
and
25
. Therefore, the process of forming the wire holding portion
26
is not complicated.
Since the width W
4
of the magnetic plate
27
is larger than the width W
1
of the outer periphery of the wire
22
, the magnetic plate
27
protects the wire
22
.
As mentioned above, the width W
4
of the magnetic plate
27
defines the outer periphery of the entire wire-wound chip inductor
21
. Therefore, when the width W
4
of the magnetic plate
27
is set to be substantially equal to the width W
4
of the magnetic plate
7
or
17
in the conventional wire-wound chip inductor
1
or
11
, the advantages mentioned above can be obtained without specially changing the external dimensions of the entire wire-wound chip inductor
21
.
In this preferred embodiment, the side wall portions
28
and
29
of the magnetic plate
27
extend to sandwich the flange portions
24
and
25
. Therefore, the decrease in inductance, which is caused by reducing the width W
2
of the core portion
23
as mentioned above, is compensated for and prevented by the side wall portions
28
and
29
.
FIGS. 3 and 4
show a wire-wound chip inductor according to a second preferred embodiment of the present invention.
A wire-wound chip inductor
31
of the second preferred embodiment includes a wire holding member
36
having a wire
32
, a core portion
33
with the wire
32
wound therearound, and flange portions
34
and
35
, and a magnetic plate
37
attached to the wire holding member
36
, in a similar manner to the wire-wound chip inductor
21
according to the above-described first preferred embodiment.
The outer periphery of the wire
32
has a width W
1
, the core portion
33
has a width W
2
, the flange portions
34
and
35
have a width W
3
, and the magnetic plate
37
has a width W
4
. Regarding these widths W
1
to W
4
, similar to the wire-wound chip inductor
21
of the first preferred embodiment, the width W
2
of the core portion
33
and the width W
3
of the flange portions
34
and
35
are preferably substantially equal, and the width W
4
of the magnetic plate
37
is preferably larger than the width W
2
of the core portion
33
and the width W
3
of the flange portions
34
and
35
. The width W
4
of the magnetic plate
37
is also preferably larger than the width W
1
of the outer periphery of the wire
32
.
Therefore, the wire-wound chip inductor
31
of the second preferred embodiment provides advantages that are substantially similar to those achieved by the wire-wound chip inductor
21
of the first preferred embodiment.
The structure of the wire-wound chip inductor
31
according to the second preferred embodiment is characterized in that a pair of side wall portions
38
and
39
for sandwiching the flange portions
34
and
35
extend from both widthwise ends of the magnetic plate
37
to positions such that they completely cover the wire
32
at three sides thereof. This structure makes it possible to further improve the function of the magnetic plate
37
for protecting the wire
32
, and the function of the side wall portions
38
and
39
for compensating for the decrease in inductance due to the reduction in the width W
2
of the core portion
33
.
Although not shown, the lower surface of the magnetic plate
37
may have a recess for receiving the upper surfaces of the flange portions
34
and
35
to accurately position the magnetic plate
37
and the wire holding member
36
. This also applies to the first preferred embodiment mentioned above.
FIGS. 5 and 6
show a wire-wound chip inductor according to a third preferred embodiment of the present invention.
A wire-wound chip inductor
41
of the third preferred embodiment includes a wire holding member
46
having a wire
42
, a core portion
43
with the wire
42
wound therearound, and flange portions
44
and
45
, and a magnetic plate
47
attached to the wire holding member
46
, in a manner similar to the wire-wound chip inductor
21
of the first preferred embodiment or the wire-wound chip inductor
31
of the second preferred embodiment mentioned above.
The outer periphery of the wire
42
has a width W
1
, the core portion
43
has a width W
2
, the flange portions
44
and
45
have a width W
3
, and the magnetic plate
47
has a width W
4
. Regarding these widths W
1
to W
4
, similar to the wire-wound chip inductor
21
of the first preferred embodiment or the wire-wound chip inductor
31
of the second preferred embodiment, the width W
2
of the core portion
43
and the width W
3
of the flange portions
44
and
45
are preferably substantially equal, and the width W
4
of the magnetic plate
47
is preferably larger than the width W
2
of the core portion
43
and the width W
3
of the flange portions
44
and
45
. The width W
4
of the magnetic plate
47
is also preferably larger than the width W
1
of the outer periphery of the wire
42
.
Therefore, the wire-wound chip inductor
41
of the third preferred embodiment provides advantages that are substantially similar to the advantages achieved by the wire-wound chip inductor
21
of the first preferred embodiment.
The structure of the wire-wound chip inductor
41
according to the third preferred embodiment is characterized in that the magnetic plate
47
does not have side wall portions like the side wall portions
28
and
29
shown in FIG.
1
and has a flat plate configuration. The magnetic plate
47
thus shaped like a flat plate also protects the wire
42
.
The lower surface of the magnetic plate
47
has a recess
48
for receiving the upper surfaces of the flange portions
44
and
45
to accurately position the magnetic plate
47
and the wire holding member
46
.
While the present invention has been described with reference to the illustrated embodiments, it is to be understood that the invention is not limited to the disclosed preferred embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
For example, while the illustrated core portions
23
,
33
, and
43
have a substantially rectangular cross section, the core portions may have a cross section of other shapes, such as a circle and an ellipse.
The magnetic plate
27
,
37
, or
47
may be placed on both sides of the wire holding member
26
,
36
, or
46
instead of being placed on only one side thereof.
As mentioned above, according to preferred embodiments of the present invention, the width of the core portion in the wire holding member and the width of the flange portions are substantially equal to each other, and the width of the magnetic plate, which is attached to the core portion to link the flange portions, is larger than the widths of the core portion and the flange portions. Therefore, the width of the magnetic plate defines the outer periphery of the entire wire-wound chip inductor, and the width of the core portion is smaller than that of the outer periphery of the wire-wound chip inductor. This makes it possible to reduce the stray capacitance generated between adjacent portions of the wire, and to thereby improve the high-frequency characteristics of the wire-wound chip inductor.
As mentioned above, since the width of the flange portions is substantially equal to the width of the core portion while the width of the core portion is reduced, the process for forming the wire holding member is not complicated. This avoids increases in the manufacturing cost of the wire holding member and the wire-wound chip inductor.
In preferred embodiments of the present invention, when the width of the magnetic plate is larger than the width of the outer periphery of the wire, the magnetic plate protects the wire. Therefore, it is possible to prevent the wire-wound chip inductor from being seriously damaged due to the stripping of an insulating coating on the wire or the breaking of the wire.
When the magnetic plate has a pair of side wall portions extending from both widthwise ends thereof so as to sandwich the flange portions, the decrease in inductance due to the reduction in width of the core portion can be advantageously compensated for by these side wall portions.
When the aforesaid pair of side wall portions extend to such positions so as to cover the wire, it is possible to further improve the function of the magnetic plate for protecting the wire, and to further improve the function of the side wall portions for compensating for the decrease in inductance due to the reduction in width of the core portion.
Claims
- 1. A wire-wound chip inductor, comprising:a wire holding member having a core portion with a wire wound therearound, and flange portions extending from both ends of said core portion, the wire holding member including the core portion and the flange portion all being formed completely of magnetic material, and the wire holding member being a single unitary member; and a magnetic plate attached to said wire holding member to connect said flange portions; wherein an outer periphery of said wire wound around said core portion, said core portion, said flange portions, and said magnetic plate have respective widths measured in a direction perpendicular to a longitudinal axis of the wire-wound chip inductor, the width of said core portion and the width of said flange portions are substantially equal to each other, and the width of said magnetic plate is larger than the widths of said core portion and said flange portion.
- 2. A wire-wound chip inductor according to claim 1, wherein the width of said magnetic plate is larger than the width of the outer periphery of said wire wound around said core portion.
- 3. A wire-wound chip inductor according to claim 1, wherein said magnetic plate has a pair of side wall portions extending from ends thereof so as to sandwich said flange portions.
- 4. A wire-wound chip inductor according to claim 3, wherein said pair of side wall portions extend such that said side wall portions of said magnetic plate partially cover said wire on said wire holding member at two opposite side surfaces thereof.
- 5. A wire-wound chip inductor according to claim 3, wherein said pair of side wall portions extend such that said side wall portions of said magnetic plate completely cover said wire on said wire holding member at two opposite side surfaces thereof.
- 6. A wire-wound chip inductor according to claim 3, wherein the width of said magnetic plate defines an outer periphery of the wire-wound chip inductor.
- 7. A wire-wound chip inductor according to claim 1, wherein the magnetic plate has a substantially U-shaped configuration.
- 8. A wire-wound chip inductor according to claim 7, wherein a portion of said wire holding member fits within said U-shaped configuration of said magnetic plate.
- 9. A wire-wound chip inductor according to claim 1, wherein an upper interior surface of said magnetic plate includes a recess for receiving an upper surface of the wire holding member.
- 10. A wire chip inductor, comprising:a wire holding member having a unitary core portion that is completely magnetic with a wire wound around only the completely magnetic unitary core portion, and flange portions extending from both ends of said core portion; and a magnetic plate attached to said wire holding member to connect said flange portions; wherein the magnetic plate partially surrounds the wire holding member on at least two sides of said wire holding member and an outer periphery of the magnetic plate alone defines an outer periphery of the wire-wound chip inductor.
- 11. A wire-wound chip inductor according to claim 10, wherein the magnetic plate has a substantially U-shaped configuration.
- 12. A wire-wound chip inductor according to claim 11, wherein a portion of said wire holding member fits within said U-shaped configuration of said magnetic plate.
- 13. A wire-wound chip inductor according to claim 10, wherein an upper interior surface of said magnetic plate includes a recess for receiving an upper surface of the wire holding member.
- 14. A wire-wound chip inductor according to claim 10, wherein an outer periphery of said wire wound around said core portion, said core portion, said flange portion, and said magnetic plate have respective widths measured in a direction perpendicular to a longitudinal axis of the wire-wound inductor, the width of said core portion and the width of said flange portions are substantially equal to each other, and the width of said magnetic plate is larger than the widths of said core portion and said flange portions.
- 15. A wire-wound chip inductor according to claim 14, wherein the width of said magnetic plate is larger than the width of the outer periphery of said wire wound around said core portion.
- 16. A wire-wound chip inductor according to claim 10, wherein said magnetic plate has a pair of side wall portions extending from ends thereof so as to sandwich said flange portions.
- 17. A wire-wound chip inductor according to claim 16, wherein said pair of side wall portions extend such that said side wall portions of said magnetic plate partially cover said wire on said wire holding member at two opposite side surfaces thereof.
- 18. A wire-wound chip inductor according to claim 16, wherein said pair of side wall portions extend such that said side wall portions of said magnetic plate completely cover said wire on said wire holding member at two opposite side surfaces thereof.
- 19. A wire chip inductor, comprising:a wire holding member having a unitary core portion that is completely magnetic with a wire wound around only the completely magnetic unitary core portion, and flange portions extending from both ends of said core portion; and a magnetic plate attached to said wire holding member to connect said flange portions; wherein the magnetic plate has a substantially U-shaped configuration and a portion of said wire holding member fits within said U-shaped configuration of said magnetic plate.
- 20. A wire-wound chip inductor according to claim 19, wherein an outer periphery of said wire wound around said core portion, said core portion, said flange portion, and said magnetic plate have respective widths measured in a direction perpendicular to a longitudinal axis of the wire-wound inductor, the width of said core portion and the width of said flange portions are substantially equal to each other, and the width of said magnetic plate is larger than the widths of said core portion and said flange portions.
- 21. A wire-wound chip inductor according to claim 19, wherein said magnetic plate has a pair of side wall portions extending from ends thereof so as to sandwich said flange portions.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 9-272333 |
Oct 1997 |
JP |
|
US Referenced Citations (5)
