Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1999-09-13
2001-09-04
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C361S800000, C361S752000, C361S796000, C361S797000
Reexamination Certificate
active
06284970
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to electronic equipment systems and, more specifically, to an electromagnetic interference (EMI) cover for an electronics module, a method of manufacturing an EMI cover and an electronic equipment chassis employing the same.
BACKGROUND OF THE INVENTION
Electronic equipment in the telecommunications and other industries is generally designed based upon a modular format. The modular subassemblies that combine to make up an electronic assembly are generally housed in a chassis that has multiple racks with modular compartments.
The modular design provides several advantages including reliability, ease of maintenance and economic savings. For example, if a module in the electronic assembly malfunctions, a service technician can remove and replace the malfunctioning module without taking the system employing the module out of service. If necessary, the malfunctioning module can then be repaired at a service location by specialized technicians familiar with that type of module. This permits field maintenance to be carried out by less skilled personnel and also results in a more reliable system.
The type of chassis used to accommodate the modules varies depending on the environment where the equipment is located. One type of chassis commonly used in the telecommunications business has a series of modules installed adjacent to one another. This type of chassis is commonly employed, for example, to house rectifier modules that combine to make up a rectifier assembly.
Regardless of the type of electronic equipment the chassis assembly accommodates, the chassis is used to provide the framework to deliver electrical power to or from the modules and provide for electrical connectivity between modules. Because of the type of electrical components that have to be used in rectifiers or converters, power supply modules are generally of the type that will generate electromagnetic emissions that can cause interference with other nearby electronic devices. For this reason, the various regulatory agencies will generally specify a maximum level of EMI emission that a power system is permitted to radiate. Because of this, one of the major concerns of manufacturers and users of telecommunications power systems is the level of EMI emission of such a system.
One method of controlling radiated EMI emissions in a modular electronic assembly is the establishment of low impedance connections to provide a common voltage potential between a chassis and the various modules housed in the chassis. By providing a common ground voltage potential, the radiated EMI generated by differing voltages is reduced.
One prior art method of providing a common grounding voltage between each conductive case in a chassis is to couple each module to the chassis with a separate wire. This approach, however, exhibits characteristic impedances that are too high to be effective for efficient EMI control. Another conventional method employs a conductive, compliant gasketing material. However the use of gasketing materials adds to both materials and labor costs and are therefore undesirable. Another EMI control method is to provide for a direct contact between the chassis and the module cases and between cases of adjacent modules. However, even in situations where a common voltage potential can be established between module cases and the chassis or between adjacent module cases by direct contact, the degree of design tolerance necessary to provide for a direct connection common path for the modular case to the chassis or between adjacent module cases generally increases the total manufacturing cost and decreases reliability.
Accordingly, what is needed in the art is a device that is employable in an electronic equipment chassis that can establish a common voltage potential between the electronic modules and the chassis housing the modules to provide an assured grounding connection that reduces EMI emissions to an acceptable level.
SUMMARY OF THE INVENTION
To address the above discussed deficiencies of the prior art, the present invention provides an electromagnetic interference (EMI) module cover for use in an electronic module that is configured to house electrical components capable of generating such EMI emissions. In one embodiment, a conductive sidepanel has a resilient cantilever member formed therefrom with a fixed end that is integrally formed with the sidepanel and a movable end that is free of a module coupler. This configuration allows the resilient cantilever member to flex as the module is installed in a chassis. The resilient cantilever member has a boss that is formed proximate the movable free end. The boss extends outward from the sidepanel a distance sufficient to provide a conductive path between the conductive sidepanel and an adjacent conductive surface when the module is installed in the chassis.
Thus, in a broad scope, the present invention provides an EMI module cover that provides a positive contact to assure a conductive path between the electronic module and the chassis in which it resides. This positive contact equalizes voltage potentials between the module and the chassis and, thereby, reduces EMI emissions.
One embodiment of the present invention provides that the EMI module cover have a sidepanel with a plurality of resilient cantilever members. An aspect of this embodiment provides for at least one of the resilient cantilever members to have an asymmetrical orientation to at least one other of the resilient cantilever members. Another embodiment provides for an EMI module cover having a sidepanel with two resilient cantilever members that are located on opposing ends of the sidepanel.
In one useful embodiment of an EMI module cover, the invention provides for that the resilient cantilever member be formed within the perimeter of the sidepanel. This feature assures contact between the boss on the cantilever member and an adjacent conductive sidepanel by reducing the possibility of interference from fasteners or other protuberances along the edges of the module.
In yet another embodiment, the sidepanel of the EMI module cover has a cantilever member with a fixed end that is integrally formed from the sidepanel and a movable end with a module coupler. In this embodiment, the module coupler on the movable end is used to interconnect with another panel in forming an exterior cover or housing for the module. When the module coupler is engaged by a cooperating panel, the cantilever member is fixed and is no longer resilient.
In yet another embodiment of the invention, an electronics module is configured to be received within a frame of an electronics chassis. This module has an electrical components housing with interlocking opposing sidewalls, at least one of which is an EMI module cover of the type described above. Another aspect of the invention provide for an electronics equipment chassis, consisting of a frame and an electronics module configured to be received within the frame, where the module has an EMI cover with a conductive sidepanel as described above.
The present invention also provides for a method of manufacturing an EMI module cover for use on an electronics module configured to house electrical components capable of EMI emissions. The method, in one embodiment, comprises forming a conductive sidepanel having a resilient cantilever member integrally formed therefrom. The resilient cantilever member is formed with its movable end free from a module coupler, so that the resilient cantilever member can flex as the module is installed in a chassis and provide conductive contact with the chassis after installation. Proximate the movable end, a boss is formed that extends outward from the sidepanel a sufficient distance so that a conductive path between the conductive sidepanel and an adjacent conductive surface is provided.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the inventi
Buskmiller Michael R.
Byrne Vincent M.
Fontana Edward C.
Kolides Dan
Mandelcorn Yehoshua
Lucent Technologies - Inc.
Ngo Hung V
Reichard Dean A.
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