Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge
Reexamination Certificate
2001-03-15
2003-12-16
Patel, Rajnikant B. (Department: 2838)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
C361S727000
Reexamination Certificate
active
06665166
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to electronic equipment and, in particular, to systems and methods utilizing modules that are configured for providing controlled dissipation of electrostatic charges.
2. Description of the Related Art
As is known, electronic equipment is particularly vulnerable to electrostatic discharge (ESD). More specifically, an ESD event may physically damage an associated electronic component(s) or, otherwise, cause improper operation of the component(s) due to magnetic and electric fields resulting from such an event. Typically an “ESD event” is a reference to the transfer of charge as two objects become close enough for current to flow therebetween. The electrical and magnetic fields are the result of the current that flows during the discharge. When the fields couple into electrical circuits they may cause damage or disruption as a result of the discharge event.
Electronic equipment, such as “always-on” equipment, that supports hot-plugging and/or swapping of modules is particularly vulnerable to ESD. Even relatively small ESD events can couple enough energy through an open slot of such equipment to disrupt operating circuitry. For instance, when a particular module is removed from a chassis, for example, a resulting gap in shielding formed by the module-chassis assembly may enable magnetic and/or electric fields to enter the equipment. These magnetic and/or electric fields can potentially couple to electrical circuits housed within the equipment.
Insertion of a module within a chassis also may cause an ESD event. For instance, when a module is handled without proper ESD precautions, a build-up of charge may be exhibited by the module. This may result in an ESD event as the module approaches and/or engages the chassis. Oftentimes, an ESD event may be influenced by the physical configuration of the module and its respective chassis. In particular, many module/chassis configurations provide metal-to-metal first contact points (areas) where the module and chassis first engage each other during hot-plugging and/or swapping. These contact points may promote ESD events that are typically one to two orders of magnitude greater than an ESD discharge facilitated by an operator's finger, for example. Moreover, since the equipment typically is operational during such hot-plugging and/or swapping, relatively small uncontrolled ESD events can cause operational errors in the equipment.
SUMMARY OF THE INVENTION
Briefly described, the present invention relates to protection of electronic devices that are vulnerable to electrostatic discharge. In this regard, embodiments of the present invention may be construed as providing enhanced electrostatic discharge protection systems. In a preferred embodiment, the system includes a module configured to be received by an enclosure. The module incorporates an electronic component, such as a memory device, processor, and/or circuit assembly, for example, that is configured to electrically communicate with at least a portion of the enclosure when the module is received by the enclosure. The module also includes a first contact portion that is arranged to contact the enclosure as the module is received by the enclosure. Preferably, the first contact portion is formed, at least partially, of a dissipative material. So configured, when the first contact portion engages the enclosure, the electrostatic charge of the module is discharged at a controlled rate by the dissipative material and at least partially dissipated as heat.
Other embodiments of the invention may be construed as providing methods for enhancing electrostatic discharge protection in an electrical system. Typically, such a system includes an enclosure that is configured to engage and disengage a module while electrical power is applied to the system. In a preferred embodiment, the method includes the steps of: (1) providing a module configured to form an electrical path between the module and the enclosure, the module having a dissipative material electrically disposing along, at least a portion of, the electrical path; (2) electrically engaging the enclosure with the module to form the electrical path between the module and the enclosure; and (3) dissipating, at least partially, an electrostatic charge of the module as heat. Preferably, the resistive electrical path is formed between the module and the enclosure while maintaining the physical distance required to prevent arcing.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
REFERENCES:
patent: 4439809 (1984-03-01), Weight et al.
patent: 4791524 (1988-12-01), Teigen et al.
patent: 4849944 (1989-07-01), Matsushita
patent: 6097604 (2000-08-01), Hunter et al.
Anson Jon C.
Bari Mohammad M.
Gysling Peter
Oldfield Barry J.
Pommerenke David J.
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