Inductor devices – With electric and/or magnetic shielding means
Reexamination Certificate
1999-08-05
2001-01-16
Gellner, Michael L. (Department: 2832)
Inductor devices
With electric and/or magnetic shielding means
C336S192000, C336S198000
Reexamination Certificate
active
06175295
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transformer and an inductor which are used in a switching regulator, and more particularly to those using a split-type bobbin.
2. Discussion of the Background
It is conventionally known that, in various transformers and inductors for switching power supplies, leakage flux to the outside occurs during the operation of the transformer and the inductor. To shield this leakage flux, a method is generally taken in which a copper plate shield ring is provided on side surfaces of the transformer via outer peripheral portions of a core, as shown in FIG.
6
. In addition, as shown in Japanese Utility Model Registration No. 2518250 and Japanese Utility Model Registration No. 2518241, methods are disclosed in which a shielding effect similar to that of the aforementioned copper plate shield ring is obtained by forming a shield coil making use of a wire without using the copper plate shield ring.
With the above-described conventional transformer and inductor, the following problems were encountered.
Although the manufacture of the transformers and inductors is generally automated, in the manufacturing method for providing the copper plate shield ring on the side surfaces of the transformer and the inductor as shown in
FIG. 6
, the fitting and soldering in a manual operation are still the mainstream, and the number of manufacturing steps is large, and the simplification of the process and automation are hampered.
Although a method has been proposed in which, in
FIG. 7
, instead of the copper plate shield ring a chamber is provided around a bobbin upper collar portion
70
, and a shield coil
74
is formed by a wire. In this structure, a winding start and a winding end of the shield coil are connected to a terminal
71
embedded in the bobbin upper collar portion
70
so as to form a short-circuited ring. Accordingly, soldering processing of the terminal
71
is required, and in order to complete the transformer, two times of soldering processing including that for opposite-side bobbin terminals
79
is performed. Accordingly, the number of manufacturing steps increased, which is not desirable.
In
FIG. 8
, on the other hand, a shield coil
84
in the form of a short-circuited ring is formed by a wire, and after the core and the bobbin are combined, the shield coil
84
is fitted in two shield-coil receiving portions
81
formed in a bobbin upper collar portion
80
. Hence, there is a problem in the stability of the shield coil
84
, and the step of fabricating the shield coil is separately required, which is not desirable.
In the above-described structure of the shield coil using the wire, the direction of leakage flux which can be shielded is only the vertical direction of the transformer and the inductor, and an effect is not obtained with respect to the leakage flux on the overall side surfaces of the core outer legs.
SUMMARY OF THE INVENTION
In view of the above-described problems, an object of the present invention is to provide an inductance device which permits simplification or automation of the process of forming a shield coil using a wire and which is provided with a shielding effect.
Namely, in accordance with the present invention, the above object is attained by providing an inductance device having a bobbin having at least two chambers divided by a collar and a terminal embedded in the bobbin, wherein a coil is wound around the chambers and a ferrite core is mounted, in that the bobbin includes a chamber having a center hole for receiving the center leg of the core and two outer holes for each receiving the outer leg of the ferrite core in a bottom portion of the bobbin, and that a shield coil having a portion which is wound around the chamber via an upper collar of the bobbin is formed in a direction perpendicular to other bobbin chambers, a winding start and a winding end of the shield coil being connected to the bobbin terminal and being thereby short-circuited, or short-circuited to a substrate surface when the inductance device is mounted on a printed circuit board. In addition, since this shield coil has a possibility of coming into contact with a primary coil and a secondary coil wound around the other chambers in conjunction with the tendency toward a compact transformer, the shield coil can be formed with a safer structure by using a three-layered insulated wire for the purpose of satisfying the safety standards for transformers.
REFERENCES:
patent: 4900879 (1990-02-01), Buck et al.
patent: 5898354 (1999-04-01), Lee
patent: 6002319 (1999-12-01), Honma
patent: 0 825 623 (1998-02-01), None
patent: 0 901 136 (1999-03-01), None
patent: 2518241 (1996-09-01), None
patent: 2518250 (1996-09-01), None
Gellner Michael L.
Nguyen Tuyen
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
LandOfFree
Inductance device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inductance device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inductance device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520453