Transformer and electrical device using the same

Details Transformer and electrical device using the same Transformer and electrical device using the same

2001-07-25

2003-05-06

Mai, Anh (Department: 2832)

Inductor devices

Coil or coil turn supports or spacers

Printed circuit-type coil

C336S223000, C336S232000

Reexamination Certificate

active

06559750

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to transformers and electrical devices using the same. In particular, the present invention relates to a transformer to be used for a switching power supply device and to an electrical device using the transformer.
2. Description of the Related Art
FIG. 10
is an exploded perspective view of a known thin transformer. In
FIG. 10
, a transformer
1
includes flat coils
2
,
3
, and
4
which are formed by winding wires in spirals and which coaxially overlap each other with doughnut-shaped insulative sheets
5
and
6
therebetween, and core members
7
and
8
sandwiching the flat coils
2
,
3
, and
4
and the insulative sheets
5
and
6
. The flat coils
2
,
3
, and
4
coaxially overlapping each other are individually provided with holes for passing a magnetic core-leg formed in central parts of the flat coils
2
,
3
, and
4
. The core members
7
and
8
are each provided with a magnetic core-leg.
FIG. 11A
is a plan view of the flat coil
3
of the transformer
1
.
FIG. 11B
is a sectional view along line A—A of the flat coil
3
shown in FIG.
11
A. In
FIG. 11A
, the flat coil
3
is formed with a wire
3
a
wound in a spiral. An inner end
3
b
of the wire
3
a
is drawn to the outside over the other part of the wire
3
a
. An outer end
3
c
of the wire
3
c
is drawn to the outside in the same winding direction.
The thickness of the overall flat coil
3
thus formed is substantially the same as the diameter of the wire
3
a
. However, the thickness of the flat coil
3
is at least twice the diameter of the wire
3
a
in a portion of the flat coil
3
over which the inner end
3
b
of the wire
3
a
is drawn to the outside. The flat coils
2
and
4
each have the same configuration as the flat coil
3
shown in
FIGS. 11A and 11B
.
The transformer I shown in
FIG. 10
includes the flat coils
2
,
3
, and
4
overlapping each other, each having the thickness twice the diameter of the wire
3
a
, whereby the thickness of the flat coils
2
,
3
, and
4
becomes six times the diameter of the wire
3
a
. Since the transformer
1
also includes the insulative sheets
5
and
6
each having a given thickness, there is a problem in that the thickness of the transformer
1
is increased.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a transformer which can be reduced in thickness and an electrical device using the transformer.
To the end, according to an aspect of the present invention, a transformer comprises a plurality of flat coils overlapping each other, each formed by winding a wire in a spiral. Respective inner ends of the wires forming at least two of the plurality of flat coils are drawn out through a hole for passing a magnetic core-leg and over one of the plurality of flat coils. The respective inner ends are disposed on the same surface of the one of the plurality of flat coils.
The inner ends of the other two of the plurality of flat coils may be connected to each other.
In the transformer according to the present invention, respective outer ends of the wires forming two of the plurality of flat coils may be connected to each other.
The wire forming at least one of the plurality of flat coils may be a three-layer insulated wire.
The wire may be a self-welding-type three-layer insulted wire.
An electrical device according to the present invention is provided which comprises the transformer described above.
The transformer according to the present invention can be reduced in thickness by arranging the same as described above.
The electrical device according to the present invention can be reduced in thickness and in size.


REFERENCES:
patent: 5631822 (1997-05-01), Silberkleit et al.
patent: 6211767 (2001-04-01), Jitaru
patent: 05006829 (1993-01-01), None

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