Electrical connectors – Contact comprising cutter – Insulation cutter
Reexamination Certificate
2000-11-10
2001-12-04
Sircus, Brian (Department: 2839)
Electrical connectors
Contact comprising cutter
Insulation cutter
C439S941000
Reexamination Certificate
active
06325660
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electrical communications connectors and, more particularly, to a patch plug having reduced crosstalk between adjacent transmission paths.
BACKGROUND OF THE INVENTION
One type of plug used to terminate cordage (ie., multi-wire cabling) is the 110-type patch plug, manufactured by Avaya Communications of Basking Ridge, N.J. One end of the 110-type patch plug permanently terminates a multi-wire cable, while the other end mates removably to the insulation displacement contacts (IDCs) of a 110-type connecting block, which is also manufactured by Avaya Communications. 110-type patch plugs are often used in voice and data transmission applications. In such transmissions, a balanced signal transmission path is formed by each pair of conductors, called the TIP conductor and the RING conductor. A typical 8-wire cable can therefore support four different voice or data signal transmission paths.
A 110-type patch plug has one or more pairs of contacts (typically 1, 2, 3, or 4 pairs) that form the electrical connections between the conductors of a multi-wire cable and the IDCs of a 110-type connecting block. One end (i.e., the mating end) of each patch-plug contact is a blade that engages a split-beam contact of the 110-type connecting block. The other end (ie., the cable end) of each patch-plug contact has a split-beam contact (e.g., an IDC) that terminates one of the cable conductors. The blades are sequenced in a liner alternating fashion between TIP and RING conductors in order to be aligned with the split-beam contacts of a 110-type connecting block.
One common type of conventional multi-wire cabling used for telecommunications applications has one or more twisted pairs of copper wires, where each twisted pair carries the TIP and RING signals for one balanced transmission path. In order to reduce crosstalk between these transmission paths, a different twist rate is used for each different twisted pair within such cordage. A twist rate may be characterized in terms of the number of times the wires of a twisted pair circle one another over a particular length of cordage, e.g., in terms of revolutions per foot.
Near-end crosstalk (NEXT) refers to unwanted signals induced in one transmission path due to signals that are transmitted over one or more other transmission paths appearing at the end nearest to where the transmitted signals are injected. Near-end crosstalk often occurs when the wires, contacts, and/or other conductors that form the various transmission paths are in close proximity to one another. The twist rates for cordage for telecommunications applications is typically carefully selected and strictly maintained within the cordage to limit such near-end crosstalk.
Prior art patch plugs have a volume within which the twisted pairs and ultimately the individual wires are distributed from a multi-wire cable to the IDCs of a 110-type patch plug and a contact base. Lack of control over twist rates within the volume may lead to near-end crosstalk. Moreover, lack of control over routing paths within the volume may result in the levels of such crosstalk varying significantly from one patch plug/cordage assembly to another, due to variations in those routing paths from assembly to assembly. The resulting electrical/transmission performance variability may be intolerable for certain high-performance, high-speed telecommunications systems. There have been, and are, numerous arrangements for alleviating the crosstalk problem, the examples of which are shown in the aforementioned Baker et al. patents and in the Lin application. These arrangements are directed primarily to the reduction of NEXT where the connector is used to terminate cordage having two or more twisted pairs, and, for the most part, feature wire guide channels through which different twisted pairs are routed to, for example, the insulation displacement contacts (IDCs) of the connector. It has been found that closer management of the routing of the individual twisted pairs, both at the transition from the cable to the wire guide troughs and within the connector between the transition and the IDCs than is currently available, is needed to reduce near end crosstalk (NEXT) even further.
SUMMARY OF THE INVENTION
The present invention is an improved plug of the 110-type patch plug of the VISIPATCH® type for interconnecting at least four twisted pairs of wires in a cordage or cable that is designed to reduce NEXT among the pairs of wires by means of an improved wire management scheme. In a VISIPATCH® plug, the connector ends of the contact blades in the contact base face toward the cable entrance end of the plug.
In greater detail, the plug of the invention comprises a substantially hollow wire guide body portion having an input end for receiving the twisted pairs of wires in the cable and an output end having a contact base having IDCs for receiving each of the several wires of the twisted pairs in a standard horizontal array. An insert member comprises a crosstail, one end of which is insertable into the cable jacket for segregating each twisted pair in a discrete walled channel. The insert has a substantially fan shape within the body of the plug and upper and lower pair guide portions. The upper guide portion has first and second substantially parallel channels defined by the crosstail, which are separated by a wall portion and which function as separated guides for first and second twisted pairs. The insert has an output end which, when the insert is positioned in the plug body, is immediately adjacent to the IDCs at the output end thereof. Thus the first and second twisted pairs are constrained and separated from each other from within the cable jacket to their connection to the IDCs and their twist rates are maintained throughout. The lower guide portion has third and fourth channels which are defined by the crosstail but which, following the fan like shape of the insert, fan out away from each other to create a large horizontal separation from each other leading to the IDCs. Thus, the third and fourth twisted pairs are separated from each other horizontally and from the first and second pairs both horizontally and vertically. Each of the channels at the output end has a necked down portion which serves to maintain the two wires of the twisted pairs within the channel in a vertical (one on top of the other) orientation. This helps to prevent any bellying, untwisting, or separation of the wires of the pair. A cap member for the housing fits thereover, enclosing the insert within the housing and holding it in place. A crimpable metallic ring functions as a strain relief member. The ring is fitted over the cable jacket portion that surrounds the crosstail and, when crimped, affixes that portion of the cable jacket to the crosstail and, hence, the insert. This arrangement prevents movement of the plug relative to the cable when subjected to externally applied forces, such as, most often, tension, thereby supplying strain relief.
The plug of the invention manages each twisted pair over the complete distance from within the cable to the IDCs, maintaining their pair twists and creates and maintains both vertical and horizontal separation among the several pairs to minimize crosstalk.
REFERENCES:
patent: 6250951 (2000-05-01), Milner et al.
Diaz Zoila A.
Filus Wayne Scott
Konyak Michael John
Lin Chen-Chieh
Million Troy Paul
Avay Technology Corp.
Nasri Javaid
Sircus Brian
Thomas Kayden Horstemeyer & Risley LLP
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