Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1999-11-30
2001-06-26
Tso, Edward H. (Department: 2838)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
Reexamination Certificate
active
06252162
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of power filters used for chassis that house various electronic components. In particular, the invention relates to a laminated filter apparatus and method that provides an efficient and convenient means to reduce electromagnetic interference.
BACKGROUND OF THE INVENTION
Electronic devices for high-speed telecommunication and networking applications are typically housed in a metal chassis. Power is typically routed to the chassis by input power cables that are connected to a circuit board located along the backside of the chassis. This circuit board is commonly referred to as a backplane circuit board. The input power cables may, however, introduce unwanted noise and other transients into the chassis. Moreover, electromagnetic emissions generated within the chassis may exit the chassis and may propagate along the input power cables outside of the chassis.
To overcome these problems, a power line filter (i.e., electromagnetic interference/radio frequency interference filter) is typically mounted within the chassis to provide filtered power to the chassis. These filters are typically housed in a relatively large metal box-like housing having input terminals or lugs which extend through a side wall, and output cables that extend through the opposite side wall. Standard electrical capacitors are mounted within the box-like housing. The input terminals are operatively connected to one end of the capacitors, and the output cables are operatively connected to the other end of the capacitors.
Although the input terminals of a conventional filter may extend outside of the chassis, the box-like housing of the filter is typically positioned within the chassis near the top of the chassis. The input power cables to the chassis are typically attached directly to the input terminals of the filter. The output cables leading from the filter are then attached to a backplane circuit board to supply filtered power to the electronic components mounted within the chassis.
There are several disadvantages to these conventional power filters including their relatively large size. Electronic chassis typically have strict dimensional requirements, and the large size of conventional filters greatly reduces the amount space in the chassis that could otherwise be used for other various electronic functions. In addition, despite their large size, conventional filters typically are not very efficient in that they do not optimum filtering over a high frequency range with low impedance.
Moreover, mounting the housing of conventional filters within the chassis blocks the airflow through the chassis, which may result in the overheating of the various electronic components within the chassis. Also, mounting conventional filters within the chassis and routing their output cables to the backplane circuit board is a labor intensive and time consuming process that increases the installation time. Finally, there are typically high costs associated with the manufacture of conventional filters due to the number of parts required to construct the filter, and the complexity of the parts.
Accordingly, it would be desirable to have a laminated filter apparatus that overcomes the disadvantages described above, and to provide a simple and cost effective laminated filter for reducing electromagnetic interference.
SUMMARY OF THE INVENTION
One aspect of the invention provides a laminated filter apparatus for reducing electromagnetic interference including a first conductor having a first side and a second side. The laminated filter apparatus also includes a second conductor having a first side and a second side. The first insulative member is positioned between the first conductor and the second conductor. The first insulative member contacts the second side of the first conductor and the first side of the second conductor. A second insulative member includes a first side and a second side. The second side of the second insulative member contacts the first side of the first conductor. A third insulative member includes a first side and a second side. The first side of the third insulative member contacts the second side of the second conductor. A third conductor contacts the first side of the second insulative member and the second side of the third insulative member. The first, second, and third conductors each may preferably be planar members and each may be generally parallel to one another. The first, second, and third conductors each may preferably be comprised of metal. The first, second, and third insulative members each may preferably be planar members and each may be generally parallel to one another. The first, second, and third insulative members each may preferably be comprised of dielectric material. The third conductor may preferably include a surface for contacting with a chassis. The chassis may preferably be comprised of metal. An input terminal may preferably be operatively connected to the first conductor and may extend outward perpendicular from the first conductor. Similarly, an input terminal may preferably be operatively connected to the second conductor, and may extend outward perpendicular from the second conductor. The first conductor may preferably include a flange portion for connection to a circuit board disposed within a chassis. The flange portion may preferably extend outward perpendicular from the first conductor. Similarly, the second conductor may preferably include a flange portion for connection to a circuit board disposed within a chassis. The flange portion may preferably extend outward perpendicular from the second conductor. A first output cable may preferably extend from the first conductor and a second output cable may preferably extend from the second conductor. The first and second output cables may preferably be operatively connected to a fan assembly mounted within a chassis. At least the third conductor may preferably include a plurality of fasteners openings formed therein to allow the first, second, and third conductors and the first, second, and third insulative members to be secured to a chassis.
Another aspect of the invention provides a system for reducing electromagnetic interference. A first conductor having a first side and a second side and a second conductor having a first side and a second side are provided. A first insulative member is positioned between the first conductor and the second conductor and contacts the second side of the first conductor and the first side of the second conductor. A second insulative member includes a first side and a second side. The second side of the second insulative member contacts the first side of the first conductor. A third insulative member includes a first side and a second side. The first side of the third insulative member conductor contacts the second side of the second conductor. A third conductor contacts the first side of the second insulative member and the second side of the third insulative member. The third conductor includes a contact surface that contacts a chassis. The first and second conductors are each mounted to a circuit board disposed within the chassis to provide power to the circuit board. The first and second conductors each include at least one input terminal to allow a power cable to be attached to the at least one input terminal.
Another aspect of the invention provides a method of reducing electromagnetic interference. A first conductor having a first side and a second side is provided. A second conductor having a first side and a second side is also provided. A first insulative member is positioned between the first conductor and the second conductor. The first insulative member contacts the second side of the first conductor and the first side of the second conductor. A second insulative member includes a first side and a second side. The second side of the second insulative member contacts the first side of the first conductor. A third insulative member includes a first side and a second side. The first side of the third insulative
Blaszczyk Marion
Borke John B.
Greco Gerald A.
Greives Dane L.
Stamos William L.
3Com Corporation
Baniak Pine & Gannon
Tso Edward H.
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