Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1999-02-03
2001-06-05
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S050510, C361S678000, C361S690000, C361S816000, C361S818000
Reexamination Certificate
active
06242691
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to packaging for electronic devices which enables the devices to operate, and be operated, in severe environmental service conditions. More particularly, the invention pertains to such packaging which not only enhances operability in severe environmental service conditions but is stackable and modular so as to promote relatively easy field configuration, upgrading or reconfiguration based on user requirements.
BACKGROUND OF THE INVENTION
The ability of electronic equipment to survive and to be usable in severe environmental conditions is an attribute which has been recognized for many applications. Such severe environmental conditions include rain, desert heat, dust or noisy electromagnetic conditions. Other types of severe environmental conditions include mechanical vibrations generated by moving vehicles or intentionally induced, extreme electromagnetic interference.
Known housings or cases usually are intended to be rigid and mechanically resistant to deformation. The rigidity of the case is used to protect an internal instrument.
Beyond a need to protect the equipment from the environmental conditions, there is a need to be able to provide electrical signals to and to obtain or read electrical signals from the equipment. The subject electrical signals may well be provided by other adjacent equipment or transmitted to such adjacent equipment. Hence, it has also been recognized that merely protecting the equipment is often sufficient only for shipping purposes.
To use the equipment while at the same time continuing to protect it from the severe environmental conditions requires that it be possible to couple connectors to the equipment, though enclosed in protective packaging, reconfigure, replace, update or provide maintenance to the equipment. Further, one piece of electrical equipment is often advantageously located adjacent to another, different, piece of electrical equipment. Hence, it would be desirable to be able to stack or interchange packaged equipment.
Known protective systems require external cables to interconnect instruments. Such cables can, unfortunately, be lost or misplaced at times.
Thus, there continues to be a need for packaging which enables electronic equipment to survive in severe environmental conditions. Preferably such packaging will be user-friendly from the point of view of configuring packaged equipment for operation and subsequently using the equipment not withstanding the severe environmental conditions. Finally, it would be preferable if the packaging exhibited a standardized, modular, stackable aspect ratio to facilitate transportability.
SUMMARY OF THE INVENTION
In accordance with the invention, lightweight packaging for electronic equipment enables that equipment to be used in severe environmental conditions. The packaging is multi-layered and modular.
An expanded foam body or block has cavities for various component mountings and air ducts. The expanded foam body includes an outer EMI screen or bag.
The entire assembly is enclosed within a deformable plastic case. The flexible outside case provides environmental protection from dust, water, and other contaminates; and deforms when dropped to absorb shock.
The case includes front and rear covers as well as air filters, EMI filters, fans, etc. In one aspect, conductive frame-like members surround various openings of the EMI bag. In another aspect, flexible EMI joints/gaskets are located between an inner EMI coating on the case and the internal equipment. The internal equipment is thereby permitted some degree of movement without causing damage to the EMI shielding.
In a packaging method, an electrical unit is mounted in a foam carrier. The foam carrier is wrapped with an EMI conductive bag. The assembly is then enclosed in a weather proof plastic case. Alternately, the EMI conductive bag or shield can be attached to the interior of the plastic case.
In yet another aspect, where a deformable or flexible outer case is used, shock and vibration protection can be provided using an internal structural cage. The structural cage may be made from metal or composite materials. It serves a dual function, by surrounding and protecting the electrical components and also providing strength to the outside flexible case.
The structural cage can be squeezed into the outside case, preloading the foam and giving both shape and structure to the outside case. The structural cage in one aspect, can be separated from the outside case by foam. The cage, combined with the preloaded foam, provides the rigidity to stack cases one on top of another.
Traditional electronic/electrical assemblies, such as standard 19 inch rack mounted equipment, or card cages can be mounted to the internal structural cage located in the foam body components then plug into the card cage for easy removal or replacement. The housing assembly is universal, allowing “19 inch rack equipment” or many varieties of components to be plugged into the card cage using conventional means. Easy access is provided for repair and replacement.
A system can be composed of several cases, each containing a variety of pieces of equipment. An integral, spring loaded, floating electrical connector in each case provides connections between cases.
The connector uses removable pins. The cable for each component is made with pins to fit the connector. To replace a component, the component cable is also replaced by snapping the pins in or out of the floating connector.
The advantage of the inventive packaging becomes apparent since it is easy to replace or reconfigure an entire system without mechanical redesign. The floating connector is spring loaded to retract itself into the case side wall where it is protected from damage. Mating of the connector is accomplished with a spring loaded cross bar to engage the connection between cases, the operator would push in on the cross bar, extending the connector out the opposite side and into the adjacent case.
The shock and vibration isolation foam is non-conductive. Hence, there is no concern for shorting electrical components against the foam. The foam material can be optimized for shock and vibration properties since it does not serve the dual function of EMI protection. Since the foam is optimized for shock and vibration, the quantity of foam can be minimized, further reducing weight.
A conductive bag is placed around the outside of the foam to provide EMI protection. The bag is located between the outside case and the foam and is protected from the weather. To ensure continued EMI performance over time, the bag joints can be sandwiched between conductive metal frames. This method of attachment provides a gas tight seal and prevents performance deterioration over time.
Thus, a ruggedized modular packaging system for instruments not only provides EMI shielding on a modular basis, but that shielding extends between coupled modules. Built-in spring loaded connectors make inter-module connections quicker and without extra cables which can get lost.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.
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Balsley John M.
Janssen Michael
McSorley Lauren J.
Reese Kenneth C.
Wilson Mark A.
Katz Eric R.
Lockheed Martin Corporation
Reichard Dean A.
Walkenhorst W. David
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