Electrical connectors – With circuit component or comprising connector which fully... – Termination circuit
Reexamination Certificate
1999-02-05
2001-07-31
Bradley, Paula (Department: 2833)
Electrical connectors
With circuit component or comprising connector which fully...
Termination circuit
Reexamination Certificate
active
06267626
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates generally to connectors, whether single conductor or multiple conductor, and whether intended for use as single connector items, e.g. for making a separable connection to a piece of electronic apparatus, or as a part or parts of a multiple-part line connector assembly, e.g. male and female interconnecting plug and socket items, and particularly thermoelectric devices such as the couple probes, thermistors, and RTD's particularly hand-held such devices, which may be connected by a link such as a cable.
More specifically, the invention relates to connectors, which provide for suppression of radiated and/or conducted electromagnetic emissions, which would be detrimental to proper use of apparatus in which the connector is included. In particular the invention is applicable to fields of use wherein there is necessity for including an electrical or electronic circuit or device having a relatively low signal level, which might be adversely affected by such stray emissions, for example thermocouple sensor circuits.
SUMMARY OF THE INVENTION
It is known that electrical signals carried by connectors, or adjacent apparatus, may be subject to electromagnetic interference as the result of induced signals picked up from the electromagnetic radiation of adjacent electrical equipment. Such interference results from the leads, to the connector or within the connector, acting as an antenna, which senses stray electromagnetic radiation.
Various efforts have been made to avoid or suppress the result of such interference, but such efforts have been found to be inconvenient and/or expensive to implement or both. For example, it has been found in the past that interference from stray signals can be avoided by encapsulating leads in sheaths of RFI (radio frequency interference shielding) material, or by determining the strength of nearby stray signal fields and then moving all such nearby sources to a physical distance from the leads that has been calculated to prevent possibility of undesired signals being picked up by electromagnetic induction, It can be seen, readily, that such preventive methods and techniques are indeed costly and inconvenient. Other attempts to reduce or avoid interference from stray signals have involved the use of ferrite cores. Hitherto such uses have in some cases required additional circuit elements, such as insertion of a jumper cable having a permanently included ferrite core, in series with the main conductors in the circuit. Again, it is known to use ferrite beads mounted conveniently on circuit boards or molded into connectors used with computer monitors.
It is established practice, in industries that make use of thermocouple sensors to couple the sensor into a related electrical circuit by means of an electrical connector. When for example thermocouples are connected to instruments such as panel meters, controllers and transmitters, the input signal from the sensor or transducer usually travels substantial distances along fine gauge electrically conductive wire leads. The length and nature of such leads and the environment in which they must function often create conditions that favour occurrence of stray emissions. In many cases, the leads or signal wires from a sensor or thermocouple are first attached, for convenience, to an electrical connector, for coupling to an instrument or the like. As soon as the conductors of the connector are electrically coupled to the circuit, stray EMI emissions may be conducted into the circuit. Of particular importance are thermocouple connectors, which are particularly susceptible because of the long lead conductive path of the conductors themselves and the high input impedance of the instrumentation.
The term ‘ferrite’ as commonly understood in the electronics field, denotes a particulate material having one or more oxides of iron in particulate form in a carrier. This usage of the term ‘ferrite’ is to be distinguished from the usual dictionary definition, which is a generic name for a number of oxides of iron. In this specification, the term ‘ferrite’ is to be understood as including within its scope any suitable material having an absorption and/or shielding effect as concerns electromagnetic waves which may be emitted at or adjacent to a zone of completion of an electrical circuit, Known ferrite elements consist of ferrite material sintered into a convenient shape. Other known ‘ferrite’ materials for the suppression of electromagnetic interference are nickel-zinc compositions and manganese-zinc materials, of different compositions to permit selection of an optimum type for a given application; pressed parts, components, and powders are known.
OBJECTS OF THE INVENTION
Accordingly it is an object of this invention to provide means associated with an electrical connector that is capable of filtering stray signals, which may be induced in the lead or leads of a connector.
It is another object of this invention to provide apparatus which eliminates the effects of undesired stray signals in circuits which include a connector or connectors, that is uncomplicated in design, and that is relatively simple and inexpensive to produce.
it is still another object of this invention to provide means associated with an electrical connector, for eliminating the effects of undesired stray signals in the circuit or circuits in which the connector is included, that is easily adaptable to single lead or multi-lead connectors.
Another and further object of this invention is to provide means associated with an electrical connector for eliminating the effects of undesired stray signals in its circuit or circuits, that can be manufactured easily in various configurations to accommodate differing circuit requirements.
And yet another and further objective of this invention is to provide means in an electrical connector, for the elimination of the effects of undesired stray signals in its circuit or circuits, which can be readily changed and substituted in the connector by other such means of a different rating or effectiveness according to requirement.
It has been found that so-called ‘soft’ ferrite elements, as they are known in this art, when properly included in an electrical circuit, act as an electromagnetic ‘sponge’ to absorb and dissipate the unwanted electromagnetic wave energy of the conductor or conductors with which the ferrite element is associated.
REFERENCES:
patent: 4847730 (1989-07-01), Konno et al.
patent: 5213522 (1993-05-01), Kojima
patent: 5219305 (1993-06-01), Kawaguchi et al.
patent: 5246387 (1993-09-01), Liebich et al.
patent: 5370555 (1994-12-01), Smoravek
patent: 5413504 (1995-05-01), Kloecker et al.
patent: 5492482 (1996-02-01), Lockman et al.
patent: 5551893 (1996-09-01), Johnson
patent: 5842888 (1998-12-01), Belopolsky
patent: 6045406 (2000-04-01), Cortes
Hollander Milton Bernard
McKinley William Earl
Stewart Russell
Bradley Paula
Drucker William A.
Omega Engineering Inc.
Ta Tho D.
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