Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Reexamination Certificate
2000-03-02
2002-03-19
Tso, Edward H. (Department: 2838)
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
Reexamination Certificate
active
06359766
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the connection of network devices and more particularly relates to an apparatus for properly grounding network cabling prior to connection to a network device.
BACKGROUND OF THE INVENTION
In the past few years, local area networks (LANs) have gone from being an experimental technology to becoming a key business tool used by companies worldwide. A LAN is a high-speed communications system designed to link computers and other data processing devices together within a small geographic area such a workgroup, department, or a single floor of a multistory building. Several LANs can also be interconnected within a building or campus of buildings to extend connectivity.
Local area networking is a shared access technology. Shared access means that all of the devices attached to the LAN share a single communications medium, usually a coaxial, twisted pair, or fiber optic cable. The physical connection to the network is made by putting a network interface card (NIC) inside of the device to be attached, then connecting the cable to the device via a standardized connector.
The most widely-used LAN technology today is Ethernet. Ethernet networks are typically configured in either a star or bus topology. Coaxial cable was the original LAN medium and is typically used in the bus topology. In this configuration, the coaxial cable forms a single bus to which all stations are attached. This topology is rarely used in new LAN installations today because it is relatively difficult to accommodate adding new users or moving existing users from one location to another. It is also difficult to troubleshoot problems on a bus LAN unless it is very small.
Today, a star topology LAN is typically employed. In a star topology, each device is connected to a central wiring concentrator, or hub, by an individual length of twisted pair cable. The cable is connected to the device's network interface card (NIC) at one end and to a port on the hub at the other. The hubs are typically placed in wiring closets centrally located in a building.
As a result of the relatively long lengths of network cabling and circuitous routing often employed in LAN configurations, network cabling is often susceptible to buildups of electrical potential. If these buildups of electrical potential are not properly discharged, electrostatic discharge events can occur upon connection of the network cabling to network devices (e.g., network adapter cards, and hubs). The excess charge is then grounded through the networking device. If the excess charge is sufficient, damage to the electrical components of the networking device can occur. Also, the tighter circuit geometries incorporated within semiconductors used within today's networking devices has increased the susceptibility of such devices to electric discharge.
Networking devices can incorporate discharge protection circuits to mitigate the problem of electric discharge upon connection to network cabling. But, today's competitive environment has driven the price of networking devices to all-time lows, so manufacturers are often forced to make design tradeoffs in order to produce a low cost product. The addition of discharge protection circuits to a typical networking device can significantly increase the production costs of the device, thus the majority of such devices do not incorporate discharge protection circuits.
Thus, there is a need for an apparatus to provide proper grounding of network cabling prior to connection to a network device. The apparatus should be small, quick, easy to use, and cost effective. The apparatus should be independent from the network device. Finally, the apparatus should support industry standard network cable connectors, and provide a relatively large discharge capability.
These and other objects, features and advantages of the present invention will be further described and more readily apparent from the summary, detailed description and preferred embodiments, the drawing and the claims which follow.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for grounding shielded and unshielded twisted pair cabling prior to connection to a network device, such as a network interface card (NIC) or a network hub, preventing electrostatic discharge (ESD) damage to the network device. In one embodiment, a cable connector receiver is mounted on an edge of a printed circuit board. A user inserts a cable connector attached to the end of each potentially charged twisted pair cable into the cable connector receiver. A current limiting device (also mounted on the printed circuit board) coupled to the cable connector receiver discharges any excess electric potential present on the twisted pair cable. In a preferred embodiment, the current limiting device includes a resistor attached to each twisted pair signal line of the cable via the cable connector. A ground connector joins the current limiting device to an electrical ground, thus providing an electrical discharge path to the electrical ground for any excess electric potential present on the cable. After any electric potential present on the cable has been successfully discharged, the user removes the cable from the apparatus and inserts the discharged cable into the network device.
The present invention offers several advantages over the currently implemented solution of installing protection circuits onto the actual networking device. The apparatus is external to and independent from the networking device, enabling use with the ever-increasing number of networking devices that do not incorporate any ESD protection circuits. Also, the apparatus can discharge built up electric discharge potentials with a much larger KV rating than can networking devices with onboard protection circuits. Finally, the apparatus can be implemented within a standalone unit, within a grounding wrist strap, or within the networked device itself.
REFERENCES:
patent: 4580186 (1986-04-01), Parker et al.
patent: 5675486 (1997-10-01), Chang
patent: 5886431 (1999-03-01), Rutigliano
Youngman Todd Jason
Zuroski Patrick James
International Business Machines - Corporation
Nock James R.
Tso Edward H.
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