Abstract:
An insulation displacement contact terminal block for providing electrical contact with a bundle of twisted pair wires having at least two differentially driven wire-pairs, a first wire-pair diverging from a second wire-pair at a diverging point of the bundle, and a first wire of each wire-pair untwisting from a second wire of that wire-pair at an untwisting point, the terminal block comprising a first contact-pair and a second contact-pair. The first contact-pair comprising first and second insulation displacement contacts for electrical connection with respective first and second wires of the first wire-pair. The second contact-pair comprising first and second insulation displacement contacts for electrical connection with respective first and second wires of the second wire-pair. The first and second insulation displacement contacts of each contact-pair are substantially equidistant from the untwisting point and are proximate to the untwisting point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Provisional Patent Application No(s). 2011905432 filed in Australia on Dec. 23, 2011, the entire contents of which are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to electrical connectors. In particular, the present disclosure relates to electrical connectors used for balanced pair communications. 
     BACKGROUND 
     Electrical connectors such as modular plugs and jacks are commonly used as components in balanced twisted pair communications cabling reticulation networks. Applications include computer local area networks (LAN&#39;s) and telecommunications networks, where such connectors are typically used to connect terminal devices such as computers and telephone equipment to the building structured cabling system horizontal cabling. 
     One common type of modular connector used for such applications is the RJ45. International standards such as EIA-568-C.2 and ISO 11801 define the performance requirements for connectors used for balanced pair applications, and in particular for RJ45 connectors. The standards specify various levels of performance by category (e.g. Category 5e, 6 and 6A in particular). These requirements include high frequency transmission performance benchmarks, defined in terms of parameters such as near-end crosstalk (NEXT) and return loss (RL). 
     Crosstalk may be defined as unwanted signal coupling between one communications circuit and another adjacent circuit. It represents a form of interference between adjacent circuits and hence has a deleterious effect on circuit operation. The close physical spacing and layout of the conductors inside a balanced pair connector such as the RJ45 and the standardized requirements for cable pair leg assignments imply that undesirably high levels of crosstalk will be induced onto the circuits passing through the connector unless special measures are taken in the design of the connector to counteract it. When designing balanced pair connectors, a great deal of design effort is required to reduce the amount of crosstalk arising within the mated connector to a level which complies with the relevant standards requirements. 
     In order for an RJ45 connector to comply with the performance requirements of the international standards, the connector design must incorporate crosstalk compensation techniques. This is because an uncompensated jack, when mated with a plug, exhibits crosstalk characteristics which far exceed the limits imposed by the standards. In order to achieve standards compliance, a connector must not only compensate for crosstalk which arises within the jack, but also the very significant amount of crosstalk which arises in the plug. Since crosstalk increases with frequency, this becomes more important at the higher performance categories (e.g. Cat 6 and Cat 6A) because of the progressively higher frequencies involved and the more stringent standards requirements. Performance requirements are specified to 100 MHz for Cat 5e, to 250 MHz for Cat 6 and to 500 MHz for Cat 6A connectors. Thus any technique which reduces the amount of crosstalk which arises in the jack is considered very worthwhile, because it reduces the amount of crosstalk compensation required. 
     With early design connectors relatively simple capacitive crosstalk compensation measures were employed, and these were sufficient to achieve compliance with the performance requirements of the relevant standards at that time. As technology has advanced, however, computer network speeds have increased exponentially and the connector performance requirements have been commensurately tightened in the standards so as to reflect the more onerous network speed requirements. This has made it progressively more and more difficult to design a standards-compliant connector. Thus any aspect of connector design which improves a connector&#39;s transmission performance, or makes it easier for the installer to terminate or install is very worthwhile. 
     The purpose of an electric circuit is to contain a signal and guide it from the source to the receiver. At high frequencies, circuits act like transmission lines. All transmission lines have a property known as characteristic impedance. When signals travel along the transmission line, reflections are generated at points along the circuit where the circuit impedance differs from the line characteristic impedance. Reflections are undesirable on communications circuits because they represent a source of signal loss. On some types of circuits they can also cause interference back at the signal source. The return loss of a circuit provides a measure of the degree of impedance mismatch caused by such circuit impedance deviations or discontinuities. Due to its inherently unsymmetrical physical construction, a mated RJ45 connector represents a significant impedance mismatch when used at high frequencies in balanced pair circuits. 
     It is an object of the present disclosure to at least overcome some of the crosstalk and return loss problems associated with prior art electrical connectors. 
     SUMMARY 
     In a first aspect of the disclosure there is provided an insulation displacement contact terminal block for providing electrical contact with a bundle of twisted pair wires having at least two differentially driven wire-pairs, a first wire-pair diverging from a second wire-pair at a diverging point of the bundle, and a first wire of each wire-pair untwisting from a second wire of that wire-pair at an untwisting point, the terminal block comprising:
         a) a first contact-pair comprising first and second insulation displacement contacts for electrical connection with respective first and second wires of the first wire-pair,   b) a second contact-pair comprising first and second insulation displacement contacts for electrical connection with respective first and second wires of the second wire-pair,       

     wherein the first and second insulation displacement contacts of each contact-pair are substantially equidistant from the untwisting point and are proximate to the untwisting point so as to minimise crosstalk between the wire pairs, and wherein the first and second insulation displacement contacts of each contact-pair are substantially adjacent to each other and the first and second contact pairs are sufficiently remote from each other so as to minimise cross-talk between the wire-pairs and provide minimum degradation of return loss of the circuit defined by each wire-pair. 
     According to a second aspect of the disclosure there is provided an electrical jack comprising at least one insulation displacement contact terminal block according to the first aspect of the disclosure. 
     According to a third aspect of the disclosure there is provided a jack module comprising at least two electrical jacks according to the second aspect of the disclosure. 
     According to a fourth aspect of the disclosure which comprises at least one jack module which is adapted to be received and retained within a jack module housing adapted to be rack mounted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given herein below for illustration only, and thus does not limit the present disclosure, wherein: 
         FIG. 1  is a perspective view of a single insulation displacement contact terminal block according to a first embodiment of the first aspect of the disclosure. 
         FIG. 2  is a rear view of an RJ45 jack assembly according to a second aspect of the disclosure which incorporates an insulation displacement contact terminal block (hereafter “IDC terminal block”) according to a second embodiment of the first aspect of the disclosure, where the RJ45 jack assembly is depicted engaging four wire pairs of a four pair cable. 
         FIG. 3  is a rear view of an IDC terminal block according to the second embodiment of the first aspect of the disclosure depicted in  FIG. 2 , in which the angles of certain structural elements have been selected to provide the geometrical features which allow for the implementation of crosstalk reduction and optimisation of return loss. 
         FIG. 4  is a perspective view of the RJ45 jack assembly of the second aspect of the disclosure showing the IDC terminal block configuration. 
         FIG. 5  is a perspective view of the RJ45 jack assembly of the second aspect of the invention showing the IDC terminal block configuration and includes the wire connections. 
         FIG. 6  is a rear view of the RJ45 jack assembly of the second aspect of the disclosure in which four wire pairs have been removed. 
         FIG. 7  is a perspective view the RJ45 jack assembly of the second aspect of the disclosure showing the front view of the RJ45 jack housing and the receiving portion of the jack. The view also shows some of the conductive fingers which make electrical contact with an RJ45 plug electrical contacts. 
         FIG. 8  is a cutaway side view of an RJ45 plug mated with the RJ45 jack assembly of the second aspect of the disclosure in which the internal structure of the jack assembly is shown. 
         FIG. 9  is a perspective view of the RJ45 jack assembly of the second aspect of the disclosure shown in  FIG. 7  in which the front housing of the jack assembly has been removed. 
         FIG. 10  is a perspective view of a prior art modular patch panel assembly. 
         FIG. 11  is a perspective view of a modular patch panel assembly according to a fourth aspect of the disclosure, which comprises 4 IDC terminal block modules according to a third aspect of the disclosure, where each IDC terminal block module contains six RJ54 jacks according to the second aspect of the disclosure which in turn are comprised of a plurality of the IDC terminal blocks according to the first aspect of the disclosure. 
         FIG. 12  is a perspective view of a prior art modular patch panel assembly depicting 4 prior art IDC terminal block modules each containing six prior art IDC terminal block jacks integrally formed to make up the module. One module is shown with wires connected. 
         FIG. 13  is a perspective rear view of a patch panel according to the fourth aspect of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
       FIG. 1  shows a single IDC terminal block  15 . The IDC terminal block  15  is not connected to a jack housing in this drawing and it features a mount  11  upon which are mounted two pairs of Insulation Displacement Connectors (IDC&#39;s)  10 , each for connecting a single wire from a twisted wire pair. There is also a protruding portion  30  of the IDC terminal block  15  which is located centrally between contacts  10  and is shaped so as to facilitate splitting apart the twisted wire pair as the wire pair is inserted into the IDC terminal block  15 . 
       FIG. 2  depicts the rear of a RJ45 jack that is comprised of a IDC terminal block  25  contained within a first jack housing  46 . In this diagram the IDC terminal block  25  is integrally formed and features 4 pairs of IDC&#39;s  10  mounted on a mount  11 . In alternate embodiments (not shown), two IDC terminal blocks  15  could be utilised in place of a single IDC terminal block  25 . What is important is the configuration and location of each IDC pair that is located in an IDC terminal block and not how many are present on any one mount  11 . Each IDC  10  has an electrically conductive part which comprises two mutually opposed cutters  13  which the wire  16  is forced between to cut through the wire insulation and form an electrical connection between the wire  16  and the IDC  10 . Mount  11  provides the means to support the IDC&#39;s  10  in the locations described below. According to the disclosure, IDC&#39;s  10  within a pair of IDC&#39;s are placed as close together as possible and where pairs of IDCs  10  are placed as far apart as possible on the mount  11 . 
     Continuing to refer to  FIG. 2 , wires  16  are derived from bundles of twisted pair wires  18  which are enclosed in an insulated jacket forming a cable (not shown). Each pair of wires  16  that forms a twisted wire pair  18  is matched with a pair of IDC&#39;s  10 . Twisted wire pairs diverge from each other at a point of divergence  20  of the bundle. Each wire  16  of a twisted wire pair  18  diverges from its mate at an untwisting point  22 . Each of the wires  16  is received into its respective receiving part of the IDC  10  where its insulation is cut and electrical contact is made. The lengths of wire  16  comprising a pair are essentially the same from the point of untwisting  22  to the point of contact with its respective electrically contacted IDC  10 . Keeping the pairs of wires the same length assists with minimising return loss degradation. 
     In order to keep the wire pair lengths from the point of untwisting  22  to the point of contact  10  essentially the same, each IDC  10  of an IDC pair is to be positioned as close to the other as possible. This further contributes to the reduction of crosstalk. This is achieved by having the cutters  13  of the IDC&#39;s  10  arranged such that they are parallel and the planes of the cutters  13  in a pair of IDCs  10 , subtend an angle of substantially greater than 0 degrees to the centre line. This allows for the cutters  13  and hence the IDCs  10  to be mounted in close proximity to each other, such that the perpendicular distance between them is less than the width of the flat side of the IDC. This is best shown in  FIG. 3  which is a rear view of IDC terminal block  25 . Angle  12  is approximately 35 degrees and is the angle that the cutters  13  are subtended so that the distance between them  14  is shorter than  17 . 
     Further, each pair of IDCs  10  are mounted such that the planes containing the faces of a first pair and second pair of IDCs  10  are substantially orthogonal and spaced far apart, such that the spacing between any of the pairs of IDCs  10  exceeds the spacing between any two IDCs  10  forming a pair of IDCs  10 .  FIG. 3 . depicts this arrangement and further, indicated that the pairs of IDCs  10  on each side of the axis of symmetry  23  are closer to each other than they are to the IDC&#39;s  10  on the opposite side of the axis of symmetry  23 . 
       FIG. 3  also demonstrates also shows the mirrored V shaped arrangement of IDCs  10  on the mount  11 . Firstly the IDC pairs are arranged in a mirror image such that straight lines, drawn through the centres of each pair of adjacent IDCs cutters  13 , intersect to form a V shape  21  which is mirrored on the other side of the IDC terminal block  25 , across the axis of symmetry  23 . Angle  40  is approximately 150 degrees. 
     The arrangements described above minimise the amount of sheath which needs to be removed from the cable in order for it to be terminated. 
     The outer dimensions of IDC terminal blocks  15  and  25  are of standard shapes and sizes so they can be installed in standard jacks already available in the market place. Each pair of IDCs  10  (for each pair of wires  16  of a twisted wire pair  18 ) is positioned so as to maximise the distance between them within the confines of the standard outer dimension of the jack. 
       FIG. 4  shows a perspective view of an RJ45 jack  50  according to a second aspect of the disclosure which includes IDC terminal block  25  attached to the first jack housing  46  and second jack housing  48  of an RJ45 jack. The first jack housing  46  houses the IDC terminal block  25  and provides a means to connect the second jack housing  48 . 
       FIG. 5  shows a perspective view of an RJ45 jack with wires  16  inserted into the IDCs. Each wire is electrically connected to its respective IDC  10 . A cable  60  contains a plurality of twisted pair wires  18  which diverge from a divergence point  22 . The geometry of the IDC terminal block  25 , as explained above in reference to  FIG. 3 , allows for minimal untwisting of the wire pairs and also minimises the length of wire pair to wire pair divergence. 
       FIG. 7  shows a front perspective view of an RJ45 jack  50  electrical connector which consists of first and second jack housings  46  and  48  which define a socket  55  that accepts an RJ45 plug  56 . The first and second housing can be integrally formed into one housing (not shown) in an alternative embodiment. The top of the RJ45 jack  50  is fitted with a clip  52 , the purpose of which is to facilitate fixing the RJ45 jack  50  into a patch panel chassis (not shown) or wall plate (not shown) wherein the clip  52  is specially shaped to facilitate easy insertion and removal from a wall plate or patch panel chassis by inserting and applying pressure with a flat blade screwdriver as depicted in  FIG. 13 . 
       FIG. 9  shows the RJ45 jack  50  without the housings, exposing the crosstalk compensation PCBs  60  and  62 . The function of the PCBs is to effect interconnection of the input terminal pairs (not shown) to the respective output terminal pairs (not shown). The first PCB  60  is interconnected to a second PCB  62  orthogonally via PCB interconnection means  61 , to conserve space within the RJ45 jack&#39;s  50  second housing  48 . PCBs  60  and  62  contain a plurality of pairs of signal conductors (not shown) including interdigital capacitors, which are routed appropriately to compensate for and counteract crosstalk. The interdigital capacitors are comprised of suitably dimensioned and shaped PCB track conductors (not shown) connected to the circuit (not shown) on PCB  60  at locations on the PCB  60  which are in close proximity to spring contacts  54  mounted in dielectric block  56 . Spring contacts  54  are shaped and positioned to make contact with an RJ45 plug (not shown) and shaped and positioned to minimise crosstalk Further a plurality of output terminal pairs (not shown) are connected to second PCB  62 . PCB interconnection means  61  connect the conductive path pairs on the first PCB  60  to the respective conductive path pairs on the second PCB  62 , effected by means of interconnection conductors  63 , formed so as to hold the two PCB assemblies  60  and  62  in place at right angles with the interconnection conductors  63  spaced far apart so as to minimise crosstalk. The second PCB  62  is connected electrically to IDC&#39;s  10  which are mounted at the rear of the RJ45 Jack  50  and which are terminated on the PCB  62  at a set of respective IDC termination locations  64 , as well as PCB interconnection means  61  for connection to first PCB  60 . Second PCB  62  also comprise a first set of return loss compensation arrays (not shown) effected by means of suitably placed interdigital capacitors, comprised of suitably dimensioned and shaped PCB track conductors (not shown) connected to the pairs of signal conductors at a location on the PCB which is in close proximity to the IDC termination locations  64 . 
       FIG. 10  shows a prior art patch panel module  70  which includes prior art DC terminal blocks  72 . The prior art IDC terminal blocks  72  include IDCs grouped in pairs  74  The lines joining the centres of each IDC lie on a straight line compared to the conformation of the IDC terminal block  25  in which said lines form a V shape. This prior art patch panel  70  comprises a single module which contains six RJ45 sockets  55  (not shown). 
       FIG. 11  shows the rear perspective view of an embodiment of a patch panel  90  according to a third and fourth aspect of the disclosure. Patch panel  90  is a modular patch panel assembly according a fourth aspect of the disclosure which comprises four patch panel modules  100  which are themselves according to a third aspect of the disclosure. The patch panel arrangement comprises a steel patch panel frame  150  a plurality of modular connector inserts (not shown), a steel cable manager frame  160 , wherein the steel patch panel frame  150  is designed to removably accommodate the plurality of patch panel module  100 . Patch panel  90  is fitted with flanges  152  to permit mounting on a 19″ rack (not shown). The steel cable manager frame  160  is mounted by way of cable manager supports  162  and  164 . The steel cable manager frame  160  is designed to occupy minimum volume when packed, for easy screwless assembly in the field, and to snap and lock into place on the back of the patch panel  150  once assembled. The V shaped arrangement of IDCs on the rear of each patch panel module  100  can be contrasted with those on the rear of prior art patch panel  70  of  FIG. 12 . The steel patch panel frame  150  may accommodate up to twenty-four RJ style connector ports  50 , horizontally disposed. It may be fitted with an optional facia attachment (not shown) which may be used for port designation purposes and is designed to improve cosmetic appearance. 
     It will be apparent to persons skilled in the art that various modifications may be made in details of design and construction of the disclosure, without departing from the scope or ambit of the present disclosure. In particular whilst the disclosure has been described by reference to a RJ45 electrical connector it is not limited to such an application.