Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
2000-08-31
2002-04-30
Dinkins, Anthony (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C361S816000, C361S818000
Reexamination Certificate
active
06380482
ABSTRACT:
TECHNICAL FIELD
This invention relates to interconnection of electronic systems and, in particular, to the shielding of such interconnections.
BACKGROUND OF THE INVENTION
In the prior art, communications switching systems such as circuit switching systems and data switching systems have a problem with the installation and subsequent need to increase capacity of small systems. For example, telecommunication switching system (circuit-switching) manufacturers face an economic hurdle to install a system that can handle twenty telephones but can grow to one hundred telephones. The initial system that is installed to handle twenty telephones is extremely cost-sensitive to the addition of such things as external connectors for the later attachment of cables for an additional system cabinet that will provide more telephones at a later point in time. The prior art has resolved this problem as illustrated in
FIGS. 1-3
. The initial system that is installed is switching system
101
which can handle a maximum number of telephones. Switching system
101
is mounted in a rack or a cabinet. When the capacity of switching system
101
has been exceeded, the architecture of switching system
101
allows printed circuit extender
103
to be plugged into the back plane of switching system
101
so as to extend the back plane. Printed circuit extender
103
then plugs into switching system
102
that will add the additional capacity to handle more telephones. Printed circuit extender
103
plugs directly into the back plane via a slot that would normally be utilized for a printed circuit board. Hence, switching system
101
does not have to have an external connector permanently wired to the printed circuit board that allows a cable to transfer the signals from the back plane to switching system
102
. In addition, it is difficult to maintain the proper electrical characteristics when going from a back plane to a cable composed of wires without utilizing additional drivers that add greatly to the initial cost of the system. At present within the prior art, printed circuit extender
103
is simply positioned through opening
301
of
FIG. 3
in switching system
101
and a similar opening in switching system
102
. Since printed circuit extender
103
is a printed circuit board which is not adequately shielded against the radiation of electromagnetic interference (EMI), the portion of printed circuit extender
103
that is exposed as illustrated by distance
104
in
FIG. 1
can radiate electromagnetic energy causing interference. In addition, EMI can also radiate from opening
301
from switching system
101
and similarly from switching system
102
. Adding to this problem is the fact that distance
104
can vary due to mounting considerations in the field. Note, that whereas switching systems
101
and
102
are illustrated as being mounted side by side which is often the case for telecommunication systems, switching system
102
can be mounted on a rack directly below switching system
101
in a rack which is often the case for packet switching systems. Printed circuit extender
103
then would extend in the vertical direction.
To resolve these problems what is needed is a method of shielding printed circuit extender
103
utilizing an apparatus that is light and whose length is adjustable.
SUMMARY OF THE INVENTION
The foregoing problems are solved and a technical advance is achieved by an adjustable sleeve that provides electromagnetic interference (EMI) shielding, is lightweight, and is adjustable in its length. The electromagnetic compatibility sleeve is formed by attaching electromagnetic foil shields on one or both sides of an insulating material that is accordion-in-structure in a first embodiment so that its length is flexible. Advantageously, the insulating material can be a very high resistivity and magnetically lossy ferrite material to prevent eddy currents on the inner surface from causing magnetic fields within the insulating material. In a second embodiment, the sleeve is made up of telescoping sections so that the length is flexible. This flexible sleeve is attached to systems by the utilization of a mounting bracket, one for each system. Advantageously, the electromagnetic sleeve confines the radiation from a printed circuit extender to within the sleeve and prevents radiation from exiting the systems through enclosure openings by the utilization of the mounting brackets.
These and other features and advantages of the invention will become apparent from the following description of the illustrated embodiments of the invention considered together with the drawing.
REFERENCES:
patent: 3350497 (1967-10-01), Weaver, Jr. et al.
patent: 3562402 (1971-02-01), Dwyer
patent: 4115656 (1978-09-01), Aitel
patent: 6201704 (2001-03-01), Poplawski et al.
Norte David A.
Yoon Woong K.
Avaya Technology Corp.
Dinkins Anthony
Moran John C.
Oliva Carmelo
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