Coil

Details Coil Coil

2003-05-27

2004-08-10

Mai, Anh (Department: 2832)

Inductor devices

Coil or coil turn supports or spacers

Printed circuit-type coil

C336S223000, C336S232000, C336S206000

Reexamination Certificate

active

06774757

ABSTRACT:

This invention relates to a coil that may be used, for example, as a component of a transformer or as a choke.
BACKGROUND OF THE INVENTION
The applicant of the present application filed U.S. patent application Ser. No. 10/006,478 on Dec. 6, 2001, entitled “High-Frequency Large Current Handling Transformer”, which was published on Jun. 13, 2002 under US-2002-0070836-A1. The transformer disclosed in the U.S. application includes coil sheets or planar coil members
1
,
2
,
3
,
4
,
5
and
6
of metal, e.g. copper, as shown in FIG.
1
. The metallic coil sheets
1
,
2
,
3
,
4
,
5
and
6
are formed in a rectangular shape with windows
1
a
,
2
a
,
3
a
,
4
a
,
5
a
and
6
a
in their center portions. One side of each coil sheet is cut to form a slit
1
b
,
2
b
,
3
b
,
4
b
,
5
b
,
6
b
therein. Tabs
1
c
and
1
d
extend outward from the portions facing across the slit
1
b
. Similarly, tabs
2
c
and
2
d
,
3
c
and
3
d
,
4
c
and
4
d
,
5
c
and
5
d
, and
6
c
and
6
d
extend outward from the portions of the respective sheet coils
2
,
3
,
4
,
5
and
6
facing each other across the slits
2
b
,
3
b
,
4
b
,
5
b
and
6
b
. The tabs
1
c
,
2
c
,
3
c
,
4
c
,
5
c
and
6
c
provide winding start terminals, while the tabs
1
d
,
2
d
,
3
d
,
4
d
,
5
d
and
6
d
provide winding end terminals. The coil sheets
1
,
2
and
3
are stacked, with the tabs
1
d
and
2
c
interconnected and with the tabs
2
d
and
3
c
interconnected, to thereby provide a primary winding of the transformer. Similarly, the coil sheets
4
,
5
and
6
are stacked, with the tabs
4
c
,
5
c
and
6
c
interconnected and with the tabs
4
d
,
5
d
and
6
d
interconnected, to thereby provide a secondary winding. Insulating sheets
9
,
10
,
11
and
14
are disposed in such a manner that each coil sheets
1
,
2
and
3
are sandwiched between two of the insulating sheets. An insulating sheet
17
is disposed on the stack of the coil sheets
4
,
5
and
6
so as to sandwich them between the insulating sheets
17
and
14
. The insulating sheets
9
,
10
,
11
,
14
and
17
have center windows
9
a
,
10
a
,
11
a
,
14
a
and
17
a
, respectively. Two core halves of, for example, ferrite,
18
and
19
are used. The core halves
18
and
19
have center legs
18
a
and
19
a
, respectively, with grooves
18
b
and
18
c
, and
19
b
and
19
c
located on opposite sides of the respective legs
18
a
and
19
a
. Outward of the grooves
18
b
and
18
c
are outer legs
18
d
and
18
e
, respectively, and outward of the grooves
19
b
and
19
c
are outer legs
19
d
and
19
e
, respectively. The core halves
18
and
19
are combined in such a manner that the center legs
18
a
and
19
a
can be placed to extend through the center windows
1
a
-
6
a
in the coil sheets
1
-
6
and the center windows
9
a
-
14
a
and
17
a
in the insulating sheets
9
-
14
and
17
.
In manufacturing this transformer, work for stacking the metallic coil sheets and the insulating sheets alternately is necessary, which increases the cost of the transformer. Furthermore, with this arrangement, the metallic coil sheets are exposed to air and, therefore, may be oxidized and rust after long use. In addition, in order to fulfill safety standards for transformers, it must be so arranged that a sufficient creepage distance can be kept even when the insulating sheets
9
,
10
,
11
,
14
and
17
are displaced more or less with respect to is the metallic coil sheets. For that purpose, larger insulating sheets must be used, which makes transformers larger in size.
An object of the present invention is to provide a coil that requires fewer steps in manufacturing it, is hardly oxidized and is small in size.
SUMMARY OF THE INVENTION
A coil according to one embodiment of the present invention includes a coil section having a plurality of metallic coil sheets. The coil sheets are planar and each have a window in the center portion thereof. A slit is formed in each coil sheet, which extends from a location on the periphery of the window through the sheet to the outer periphery of the sheet. Connection terminals are formed on the sheet at locations facing each other across the slit. The coil sheets are stacked, and adjacent coil sheets are electrically connected with each other by the connection terminals. A core is disposed within the windows in the coil sheets. Each of the metallic coil sheets is individually coated completely with an insulating coating before the metallic coil sheets are stacked.
With the above-described arrangement, since each of the metallic coil sheet of the coil is individually pre-coated with an insulating coating, there is no need for placing an insulating sheet between adjacent coil sheets when the metallic coils sheets are stacked, which can reduce the manufacturing steps, which, in turn, can reduce the manufacturing cost. Furthermore, by covering the entire surface of each of the metallic coil sheets with an insulating coating, the metallic coil sheets are hardly oxidized and rusted. In addition, since each of the metallic sheets is individually pre-coated with an insulating coating, there is no need to take care to keep that insulating sheets are not displaced relative to the metallic coil sheets when the metallic coil sheets are stacked. Accordingly, it is not necessary to take such displacement into account when setting a creepage distance, and, therefore, the creepage distance can be set small. Then, the size of transformers can be reduced.
A plurality of coil sections may be used. The core is disposed to extend through the windows in the metallic coil sheets of the coil sections, so that the plural coil sections are inductively coupled with each other. This arrangement provides a transformer which can be manufactured at a low cost and hardly rust, and is small in size.
The insulating coatings may be formed by applying an insulative resin directly over the metallic coil sheet. Alternatively, an insulating film may be bonded to the metallic coil sheet to cover part of or the entirety of the surface of the metallic coil sheet before stacking the metallic coil sheets. The insulating resin may be used as an adhesive to bond the pre-formed insulating film to the metallic coil sheet.


REFERENCES:
patent: 5559487 (1996-09-01), Butcher et al.
patent: 6087922 (2000-07-01), Smith
patent: 6211767 (2001-04-01), Jitaru
patent: 0 608 127 (1994-07-01), None
patent: 0 767 473 (1997-04-01), None
patent: 2 369 251 (2002-05-01), None
patent: 2 373 640 (2002-09-01), None
Yamanobe et al [US2003/005276A1], Coil for Electrical and Electronic Equipment as Well as Process for Production Thereof, Mar. 2003.

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