Adding a conductive polymer or similar material to the leading edge of connectors can add an RC time constant to bring both host and peripheral devices to the same potential to protect expensive, critical equipment without causing an ESD event.
Posted by Robert Miller under Electronics & Gadgets
Patent # 7404724.
BACKGROUND OF THE INVENTION
Electrical connectors are used in a wide variety of applications. Some connectors simply transmit power (e.g., from a power source to an appropriate appliance) or signal lines to printed circuit boards, other electronic devices or to other complementary connectors. Other connectors transmit both power and signal lines through the connector interface.
Some electrical connectors also employ various types of shell structures, ground structures or the like to protect or to electrically interact with the transmission lines and their terminals within the connectors. For instance, some connectors are provided with shell structures to protect against electrostatic discharges (ESD) which are generated when the connector comes into contact with another conductive body which may be a complementary mating connector. In essence, the ESD shell is used to dissipate static charges. Connectors also may have shell structures to protect against electromagnetic interference (EMI). In essence, the EMI shell protects the electrical circuitry from externally generated radiated emissions as well as preventing electromagnetic interference from radiating outwardly of the connector. Such shell configurations can work well, especially once a connector is engaged with its complementary connector. Unfortunately, however, in connectors where shells from complementary connectors initially come into contact with each other when their connectors are engaged, it is observed that ESD may continue to damage components in one or both of the connecting devices.
Accordingly, what is needed is an improved connector configuration.
SUMMARY OF THE INVENTION
The present invention provides a method for reducing ESD damage to devices, which have separate grounds, when they are connected to one another. The charge on the first and second device grounds are equalized when the devices are connected to one another before connecting their signal lines together; but when the grounds are equalized, the transfer of charge between them is sufficiently slowed down so as to avoid harming components within the device receiving the extra charge. In one embodiment, a connector for connection with a complementary connector is provided with an inhibited shell. The inhibited shell is mounted to the connector body for connection with a shell on a complementary connector. The inhibited shell is configured (e.g., with a conductive polymer having a desired resistance) to sufficiently slow down the detrimental transfer of charge between the separate grounds on the connected devices while at the same time allowing them to equalize with one another.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.