Inductor devices – Coil or coil turn supports or spacers – Coil on a preformed support or mount
Reexamination Certificate
2002-03-15
2004-05-11
Mai, Anh (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Coil on a preformed support or mount
C336S205000, C336S198000
Reexamination Certificate
active
06734777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transformer, and more particularly to a transformer with good insulation.
2. Description of the Related Art
Generally, because the secondary side of a transformer has a high voltage, it is generally necessary to insulate the secondary winding to prevent the electric elements or users from being harmed by high voltage. However, there are many shortcomings to several conventional method of insulating the secondary winding.
A conventional transformer, as shown in
FIG. 1
a
, is composed of a bobbin
10
a
, a core structure and an insulating shell
30
. The core structure comprises two E type cores
50
which are coupled together by being inserted into the two ends of the bobbin
10
a
respectively. The bobbin has a primary side
20
a
and a secondary side
20
b
. The primary side
20
a
is provided with a primary winding (not shown) and the secondary side
20
b
is provided with a secondary winding (not shown). The primary side
20
a
is separated from the secondary side
20
b
by a first separating flange
25
. In addition, the primary winding is electrically coupled to at least one of the primary pins
21
, and the second winding is electrically coupled to at least one of the secondary pins
22
. The secondary side
20
b
further comprises a plurality of secondary flanges
27
for producing several dividing voltages. Namely, the primary winding and the secondary winding are formed along the same axis of one bobbin. Moreover, the transformer further comprises an insulating shell
30
to insulate the secondary winding from outside. The insulating shell
30
encloses the whole bobbin
10
a.
However, in the conventional transformer shown in
FIG. 1
a
, because only the first flange
25
is used to insulate the secondary winding from the primary winding, the primary winding is not completely insulated from the secondary winding. The creepage distance between the primary winding and the secondary winding may be not enough when the primary winding and the secondary winding are formed at the primary side
20
a
and the secondary side respectively, due to poor design or error in the production process, for example, the first flange
25
is too low or the secondary winding is wound too thick. In this case, the high voltage at the secondary winding may be short-circuited to the primary winding, thereby decreasing the efficiency of the transformer.
Another conventional method is to insulate the secondary winding by using an insulating glue. In
FIG. 1
b
, a conventional transformer with an insulating glue is comprised of a bobbin
10
b
, a core structure and a container
60
. The core structure comprises two E type cores
50
which are coupled together by being inserted into the two ends of the bobbin
10
a
respectively. The bobbin
100
has a primary side
20
a
and a secondary side
20
b
. The primary side
20
a
is provided with a primary winding (not shown) and the secondary side
20
b
is provided with a secondary winding (not shown). The primary side
20
a
is separated from the secondary side
20
b
by a first separating flange
25
. In addition, the primary winding is electrically coupled to a least one of the primary pins
21
, and the second winding is electrically coupled to a least one of the secondary pins
22
. The secondary side
20
b
further comprises a plurality of second flanges
27
to produce several dividing voltages. Namely, the primary winding and the secondary winding are along the same axis direction of one bobbin. The transformer further comprises a container
60
to hold the secondary winding from the environment. The container
60
is used to include the bobbin
10
b
and the core structure. The insulating glue is added into the container
60
to insulate the secondary winding from environment.
However, the transformer shown in
FIG. 1
b
not only has the problem about creepage distance, but it is also difficult to implement the transformer in the Surface Mount Device (SMD) type. Instead, the transformer must be implemented in stitch type because the bobbin
10
b
must be placed in the container
60
. However, it is very difficult to control the potting height to cover the bobbin
10
b
but still expose the pins
21
and
22
because the pins
21
and
22
in the transformer of the SMD type and the lower surface of the bobbin
100
are almost in the same plane. Furthermore, the insulating glue must be added in a vacuum environment to prevent bubbles from being formed when the insulating glue is added into the container
60
.
In view of this, it is desirable to develop a novel transformer to solve the problems mentioned above.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a transformer wherein the high voltage side (secondary side) is insulated completely. The transformer of the present invention comprises a bobbin, an insulating shell and a core structure. The surface of the bobbin is provided with a plurality of flanges, a plurality of secondary side pins and secondary winding. The flanges are formed on the surface of the bobbin to form a plurality of slots on the surface of the bobbin. A conductive wire is wound on those slots to form the secondary winding. The secondary winding is electrically coupled to the pins.
The insulating shell is comprised of an upper insulating cover and a lower insulating cover, wherein the upper insulating cover covers the top surface of the bobbin and the lower insulating cover covers the bottom surface of the bobbin. Namely, the secondary winding and surface thereof are enclosed by the upper insulating cover and the lower insulating cover. Consequently, the secondary winding of the bobbin is completely electrical insulated from the environment. Moreover, another conductive wire is wound on the insulating shell to server as the primary winding and electrically coupled to the primary pins.
The upper insulating cover further comprises a top extending board, and the lower insulating cover further comprises a bottom extending board. The top extending board and the bottom extending board extend beyond the secondary pins. Alternatively, the top extending board and the bottom extending board enclose the secondary pins exactly.
REFERENCES:
patent: 4510478 (1985-04-01), Finkbeiner
patent: 4916424 (1990-04-01), Kijima
patent: 6078240 (2000-06-01), Huang
patent: 6344786 (2002-02-01), Chin
Chou Heng-Cheng
Huang Ren-Jye
Wu Chen-Feng
Yeh Ming
Birch & Stewart Kolasch & Birch, LLP
Delta Electronics , Inc.
Mai Anh
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