The present invention relates to multi-port telecommunication connector panels, specifically to measures for minimizing or preventing inter-port and intra-port crosstalk, and to measures for otherwise enhancing the performance of such connector panels.
Due to advancements in telecommunications and data transmissions speeds over balanced, twisted-pair cables, the connectors (such as jacks, plugs, patch panels, cross connects, etc.) are now a critical impediment to high performance data transmission at higher frequencies. Performance characteristics, particularly crosstalk and return loss, degrade beyond acceptable levels at higher frequencies. This degradation is particularly true for system operation at category 6 and category 6A levels.
When an electric signal is carried on a signal line that is in close proximity to another signal line or lines carrying a signal or signals, such as in the case of adjacent pins of contacts in the connector, energy from one signal line can be coupled into adjacent signal lines by the electric field generated by the potential between the two signal lines and the magnetic field generated as a result of the changing electrical fields. This coupling, whether capacitive or inductive, is called crosstalk.
Crosstalk is a noise signal that degenerates the signal-to-noise margin or ratio (S/N) of the system. In telecommunication systems, reduced S/N margins result in greater error rates in the information conveyed on the signal line. The S/N margin must satisfy set performance criteria for the system category involved.
Crosstalk problems could be overcome by increasing the spacing between the signal lines, or by shielding the individual signal lines. In many cases, the wiring is preexisting and standards define the geometries and pin definitions for connectors, making the necessary changes to such systems cost-prohibitive. In the specific case of communication systems using balanced, twisted-pair wiring, standards defining connector geometries and pin out definitions are in effect, but were created prior to the need for high speed data communications.
These standards have created a large base of wiring and connectors and a need for connectors capable of meeting the requirements of high speed communications, while maintaining compatibility with the original connectors. The standard connector geometries and pin outs are such that a great deal of crosstalk occurs at higher signal frequencies.
Numerous connector constructions have been developed to address crosstalk problems. Minimizing near end cross talk between the signal lines of an individual connector typically involves counteracting a noise signal in a line by inducing in that line a signal equal to and opposite to the noise signal such that the induced noise signal is effectively cancelled by the induced correction signal. Examples of such connectors are disclosed in U.S. Pat. Nos. 5,432,484, 5,673,009 and 6,796,847, the subject matter of each of which is herein incorporated by reference. Alien crosstalk between the conductors of adjacent connectors has been addressed by applying separate dedicated shielding components around individual connectors. See, e.g., patent application publication No. US 2009/0098777.
As used in this application, the terms “top”, “bottom”, “side”, “front”, “rear” and the like are intended to facilitate the description of the electrical connector panel and parts thereof. Such terms are merely illustrative of the connector panel and its parts, and are not intended to limit the connector panel and its parts to any specific orientation.
The invention utilizes electrically conductive housing portions and barriers that separate and serve to isolate adjacent ports and adjacent sets of insulation displacement contacts associated with different ports. As used herein to describe such housing portions and barriers, the term “electrically conductive” means containing conductive materials or elements that impart at least partial local conductivity substantially throughout such housing portions and barriers.
From one perspective, the invention is embodied in a telecommunications connector assembly comprising an electrically conductive housing defining at least one port having a plug receiving cavity. A set of jack contacts in the port is adapted to mate with respective contacts of an inserted connector plug, and is electrically connected to a set of insulation displacement contacts. The jack contacts are substantially surrounded by and electrically insulated from the housing. An electrically conductive isolation barrier is adjacent the set of insulation displacement contacts and is electrically connected to the housing. Thus, the isolation barrier would separate the sets of insulation displacement contacts of adjacent ports. The isolation barrier may be integrally formed with the housing.
From another perspective, the invention is embodied in a multi-port telecommunications panel comprising a mounting circuit board, a plurality of sets of insulation displacement contacts on the circuit board, and a plurality of sets of jack contacts on the circuit board. Each set of jack contacts is electrically connected to a respective set of insulation displacement contacts and is adapted to mate with respective contacts of an inserted connector plug. An electrically conductive housing, which is electrically insulated from the jack contacts, substantially surrounds and separates the sets of jack contacts to define a plurality of ports, each port having a plug receiving cavity aligned with a respective set of jack contacts. An electrically conductive isolation barrier is disposed between each pair of adjacent sets of insulation displacement contacts. Each isolation barrier is electrically connected to the front housing. The isolation barriers may be integrally formed with the housing. The jack contacts and the insulation displacement contacts may extend from opposite sides of the circuit board, or from the same side of the circuit board.
From yet another perspective, the invention is embodied in a multi-port telecommunications panel comprising a mounting circuit board having opposed front and rear faces; a plurality of sets of insulation displacement contacts extending from the rear face of the mounting circuit board; a plurality of sets of jack contacts extending from the front face of the mounting circuit board; and an electrically conductive front housing at the front face of the mounting circuit board substantially surrounding the sets of jack contacts individually and collectively to define a plurality of ports, each with a plug receiving cavity aligned with a respective set of jack contacts. Each set of jack contacts is electrically connected to a respective set of insulation displacement contacts and is adapted to mate with respective contacts of an inserted connector plug. The front housing is electrically insulated from the jack contacts and has an isolation barrier associated with each pair of adjacent sets of insulation displacement contacts. Each isolation barrier extends rearward beyond the mounting circuit board between the adjacent sets of insulation displacement contacts.
Each set of jack contacts preferably is supported in a module having an electrically insulating frame. Preferably, adjacent insulation displacement contacts of adjacent sets of insulation displacement contacts are offset. And adjacent insulation displacement contacts of each set preferably are offset.
Each isolation barrier preferably comprises a pair of spaced substantially parallel plates occupying the region between the adjacent sets of insulation displacement contacts. The plates preferably are paddle-shaped and are substantially congruent. Each isolation barrier preferably passes through a respective slot in the mounting circuit board. Each slot preferably is at an edge of the mounting circuit board. The front housing and the isolation barriers preferably are made of a conductive thermoplastic resin.
An electrically insulating rear housing covers the rear face of the mounting circuit board and flanks the insulation displacement contacts. The rear housing has an opening aligned with each slot in the mounting circuit board, through which opening an isolation barrier extends. The rear housing is secured to the front housing by fasteners, such as screws, thus sandwiching the mounting circuit board therebetween.
If the front housing does not completely cover the front of the mounting circuit board, an electrically insulating shroud can be provided that surrounds the front housing and covers the remainder of the front of the mounting circuit board. The shroud is secured to the rear housing, preferably by snap tabs that project from the shroud and engage mating shoulders on the rear housing.
The mounting circuit board has electrically conductive traces that connect the jack contacts to their respective insulation displacement contacts. The mounting circuit board preferably includes a ground plane for each port adjacent its electrically conductive traces for optimizing common mode impedance.
A preferred embodiment of the disclosed invention, which includes the best mode for carrying out the invention, is described in detail below, purely by way of example, with reference to the accompanying drawing, in which:
Referring to
A front (nose) housing 32, preferably molded of a conductive thermoplastic material, covers the contact modules 24. The material for the front housing 32 preferably is a stainless steel fiber filled thermoplastic resin. A preferred example of such material is a thermoplastic marketed under the name FARADEX by SABIC Innovative Plastics of Pittsfield, Mass. Alternatively, front housing 32 could be completely metallic. Front housing 32 has six port openings 25 into respective plug receiving cavities 27, each aligned with the jack contacts of a respective contact module 24. Two mounting slots 23 above each port opening accommodate a port identification label. Front housing 32 also has hooks 41 at one end, and a tab with a screw hole 43 at the opposite end, that facilitate mounting the connector panel 20 in a common metal support panel (see
A rear housing 34, molded of an insulating thermoplastic material, covers the rear face 30 of the circuit board and has portions 35 that extend rearward and flank the IDCs 28. Fasteners, preferably in the form of screws 38, pass through holes 40 in rear housing 34 and holes 42 in circuit board 22, to threadably engage blind holes 44 in the back of front housing 32. An insulating molded plastic shroud 36 surrounds front housing 32 and covers the remainder of the front face 26 of the circuit board. Shroud 36 has resilient snap tabs 37 that mate with recesses 39 in rear housing 34. Shroud 36 could be eliminated if the front housing 32 were broad enough to cover the entire circuit board 22.
The screws 38, which secure the front and rear housings together, force the sandwiched mounting circuit board 22 into position against front housing 32 to take up tolerances. Referring to
Front housing 32 has interlocking features that ensure proper alignment with contact modules 24, thus ensuring proper mechanical functioning of the contact system. Referring to
Front housing 32 also has four isolation barriers 72 cantilevered from its elongated walls 74. Isolation barriers 72 extend rearward through edge slots 76 in mounting circuit board 22, through aligned openings 78 in rear housing 34, and between adjacent sets of IDCs 28. Each isolation barrier 72 comprises a pair of spaced, congruent paddle-shaped plates 73 separated by an air gap 75. Referring to
The electrically conductive nature of front housing 32 is inherent in all of its parts. Thus, intermediate walls 64 shield the contacts of adjacent contact modules from one another, minimizing alien crosstalk at the ports. Further, the face and the surrounding walls 62, 74 of front housing 32 shield the contacts of all ports from extraneous electromagnetic interference. In addition, the isolation barriers 72 between the sets of IDCs provide improved crosstalk isolation. A solid barrier would function to provide some improvement (reduction) in the level of alien crosstalk (as compared to no barrier) because of the solid barrier's shielding effect, but it would still result in secondary capacitive coupling between adjacent IDCs. Split isolation barriers with an intermediate air gap 75 between plates 73 are preferred because they provide better crosstalk isolation by further reducing the coupling and, therefore, alien crosstalk.
Several structures electrically insulate the jack contacts 29 of each contact module 24 from the conductive front housing 32. Referring to
Details of the spring-biased compensation circuit board and contact arrangement are disclosed in the aforementioned application Ser. No. 12/314,613. Crosstalk compensation typically is applied to the connectors at one or more of three locations in the manner described in application Ser. No. 12/314,613, namely: (1) near the distal ends of the jack contacts through the spring-mounted compensation circuit board 96, (2) at the jack contact mounting locations through the mounting circuit board 22, and (3) at the IDC locations through the mounting circuit board 22. Compensation can be applied at other locations as would be understood by those skilled in the art.
Compensation elements and related traces are present in all layers of the circuit board 22. The compensation elements are in the form of plates 102. The sizes and relative positions of the compensation plates provide appropriate capacitive and inductive coupling for cancellation of crosstalk induced in other portions of the electrical connector panel.
The preferred embodiment of the invention illustrated and described herein is merely an example. It will be understood by those skilled in the art that other embodiments incorporating various changes and modifications also are considered to be within the scope of the invention, which is defined in the appended claims. For example, and without limitation, the electrically conductive front housing may be formed separately from the electrically conductive isolation barriers, with provision made for the barriers and the front housing to become electrically connected when the connector panel is assembled. The isolation barriers, whether integral with or separate from the front housing, could extend around, rather than through the mounting circuit board. For a front-access connector panel, in which the insulation displacement contacts and the jack contacts are on the same (front) face of the mounting circuit board, the isolation barriers would be fully disposed in front of the mounting circuit board. The number of ports can be fewer or greater than the six ports of the preferred embodiment; and the number of jack contacts per set can be fewer or greater than the eight jack contacts per set of the preferred embodiment.
This application claims the benefit of Provisional Application Ser. No. 61/193,654, filed Dec. 12, 2008. This application also is related to application Ser. No. 12/285,428 of Shadi A. AbuGhazaleh and Douglas P. O'Connor, filed Oct. 3, 2008, and entitled Crosstalk Prevention Cover (published under No. US 2009/0098777), and application Ser. No. 12/314,613 of Shadi AbuGhazaleh, Joseph E. Dupuis, Naved S. Khan, Christopher W. Gribble and Douglas P. O'Connor, filed Dec. 12, 2008, and entitled Electrical Connector with Separate Contact Mounting and Compensation Boards. The subject matter of each of the aforementioned three applications is herein incorporated by reference in its entirety.
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