Electrical connectors – With stress relieving means for conductor to terminal joint – Conductor gripped by or entirely within connector housing
Reexamination Certificate
2000-05-26
2001-06-26
Ta, Tho D. (Department: 2833)
Electrical connectors
With stress relieving means for conductor to terminal joint
Conductor gripped by or entirely within connector housing
C439S418000, C439S934000, C439S344000, C174S027000
Reexamination Certificate
active
06250951
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a wire spacer for placement in a cable having four twisted wire pairs enclosed in a flexible insulating sheath to prevent the wire pairs from becoming intertwined when the sheath with the twisted wire pairs therein or the twisted wire pairs without the sheath are radially compressed by a connector strain relief. More particularly, the present invention relates to an electrical connector and a cable having the wire spacer, and to certain forms of the wire spacer.
BACKGROUND OF THE INVENTION
Due to advancements made in telecommunications and data transmissions speeds over unshielded twisted wire pair cables, the connectors (such as jacks and plugs) have become critical impediments to high performance data transmission at high frequencies. Some performance characteristics, particularly due to near end crosstalk, degrade beyond acceptable levels at the higher frequencies, particularly for category 5 and category 6 environments.
When electrical signals are carried on a signal line or wire which is in close proximity to another signal line or other signal lines, energy from one signal can be coupled onto adjacent signal lines by means of the electric field generated by the potential between the two signal lines and the magnetic field generated as a result of the changing electric fields. This coupling, whether capacitive or inductive is called crosstalk, when the coupling occurs between two or more signal lines.
Crosstalk is a noise signal and degrades the signal-to-noise margin (s
) of a system. In communications systems, reduced s
margin results in greater error rates in the information conveyed on the signal lines.
One way to overcome this crosstalk problem is to increase the spacing between the signal lines. Another method that can be used is to shield the individual signal lines. However, in many cases, the wiring is pre-existing and standards define geometries and pin definitions for connectors making the necessary changes to such systems cost prohibitive. In this specific situation of communications systems, using unshielded twisted pair wiring cables is the only practical alternative.
Performance requirements for conductive pathways are set forth in ANSI/TIA/EIA-568-A, (commercial building telecommunications cabling standard). In category 6 draft-addendum in that standard, the minimum acceptable performance values are 54 dB at 100 MHz, 48 dB at 200 MHz and 46 dB at 250 MHz.
Crosstalk generated at the connection between cables and the connectors, particularly plug connectors has become a significant problem. A very significant problem involves the deformation of the cable by the connector strain relief.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrical connector for communications systems, a wire spacer for an electrical connector or a cable for connection to a communications systems electrical connector which will reduce or not induce crosstalk in the system.
Another object of the present invention is to provide an electrical connector, wire spacer, or cable with reduced crosstalk, but without providing shielding and without changing the standardized form of the connector or the cable.
A further object of the present invention is to provide an electrical connector, wire spacer and cable with reduced crosstalk which is simple and inexpensive to manufacture and to install.
Yet another object of the present invention is to provide an electrical connector for communications systems, a wire spacer for an electrical connector or a cable for connection to a communications systems electrical connector with greater mechanical strain relief by increasing the interference between the cable and the connector strain relief for resisting axial forces at the cable-strain relief interface.
The foregoing objects are basically obtained by an electrical connector comprising a connector body, a cable strain relief and a wire spacer. The connector body has a cable cavity at a cable connection end of the connector body. The strain relief is coupled to the connector body adjacent the cable connection end, and extends into the cable cavity. The wire spacer is mounted in the cable cavity adjacent the strain relief, and has a central core and four radially outwardly projecting flanges. The flanges are angularly spaced from one another by angles of substantial 90 degrees.
The foregoing objects also obtained by a wire spacer for separating twisted wire pairs of cable extending into an electrical connector strain relief. The wire spacer has a central core extending along a longitudinal axis and four flanges extending radially relative to the longitudinal axis from the central core. The flanges are angularly spaced from one another by angles of substantially 90 degrees. Each of the flanges tapers in a direction from its free end towards the central core.
The foregoing objects are additionally obtained by an electrical cable for electrical communications systems comprising four twisted pairs extending along a longitudinal axis, a flexible inflating sheath surrounding at least a longitudinal portion of the four twisted wire pairs, and a wire spacer extending axially relative to the sheath. The twisted pairs extend from at least one longitudinal end of the sheath. The wire spacer is adjacent one sheath longitudinal end. The spacer is significantly shorter than the sheath along the longitudinal axis, and includes an axially extending central core and four angular spaced flanges extending radially outwardly from the central core to define four separate chambers. Each of the chambers receives one of the twisted wire pairs to maintain separation between the pairs even when the twisted wire pairs are radially compressed.
By forming the connector, wire spacer and cable in this manner, the flanges of the wire spacer maintain the separation between the four pairs of twisted wires even when the cable is radially compressed by the strain relief of a connector. Without the wire spacer, the twisted wire pairs would be intertwined at the strain relief causing substantial crosstalk between the various wires at this point. The increased crosstalk would degrade system performance beyond acceptable levels, particularly for category 6 installations.
Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.
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Dupuis Joseph E.
Miller Alan C.
Milner John J.
Mortensen Karl E.
'Hubbell Incorporated
Bicks Mark S.
Ta Tho D.
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