# Patent

## Title
Communications connectors with self-compensating insulation displacement contacts

## Abstract

Communications connectors are disclosed that include a housing having an upper end and a lower end, the upper end of the housing including a plurality of slits that define a plurality of pillars. First and second pairs of tip and ring insulation displacement contacts (IDCs) are mounted in the housing. Each of the IDCs has an upper end that has a first slot, a lower end that has a second slot and an intermediate portion between the upper end and the lower end, the lower end being offset from the upper end. The first slot of each IDC is aligned with a respective one of the slits. The housing further includes through slots that are separated by dividers, where each of the through slots is sized to receive the upper end of a respective one of the IDCs, and each slit of the plurality of slits exposes inner edges of the first slot of a respective one of the IDCs.

## Background
RELATED APPLICATIONS
This application claims priority as a continuation of U.S. patent application Ser. No. 11/734,887, filed Apr. 13, 2007, now U.S. Pat. No. 7,503,798, which in turn claims priority as a continuation-in-part application of U.S. patent application Ser. No. 11/154,836, filed Jun. 16, 2005, now U.S. Pat. No. 7,223,115, which in turn claims priority from U.S. Provisional Patent Application Ser. No. 60/687,112, filed Jun. 3, 2005, the disclosures of each of which are hereby incorporated by reference herein in their entireties.


FIELD OF THE INVENTION
The present invention relates generally to communications connectors and, more specifically, to cross connect systems.
BACKGROUND OF THE INVENTION
In an electrical communications system, it is sometimes advantageous to transmit information signals (e.g., video, audio, data) over a pair of conductors (hereinafter a “conductor pair” or a “differential pair” or simply a “pair”) rather than a single conductor. The signals transmitted on each conductor of the differential pair have equal magnitudes, but opposite phases, and the information signal is embedded as the voltage difference between the signals carried on the two conductors. This transmission technique is generally referred to as “balanced” transmission. When signals are transmitted over a conductor such as a copper wire in a communications cable, electrical noise from external sources such as lightning, computer equipment, radio stations, etc. may be picked up by the conductor, degrading the quality of the signal carried by the conductor. With balanced transmission techniques, each conductor in a differential pair often picks up approximately the same amount of noise from these external sources. Because approximately an equal amount of noise is added to the signals carried by both conductors of the differential pair, the information signal is typically not disturbed, as the information signal is extracted by taking the difference of the signals carried on the two conductors of the differential pair; thus the noise signal is cancelled out by the subtraction process.
Many communications systems include a plurality of differential pairs. For example, high speed communications systems that are used to connect computers and/or other processing devices to local area networks and/or to external networks such as the Internet typically include four differential pairs. In such systems, the conductors of the multiple differential pairs are usually bundled together within a cable, and thus necessarily extend in the same direction for some distance. Unfortunately, when multiple differential pairs are bunched closely together, another type of noise referred to as “crosstalk” may arise.
“Crosstalk” refers to signal energy from a conductor of one differential pair that is picked up by a conductor of another differential pair in the communications system. Typically, a variety of techniques are used to reduce crosstalk in communications systems such as, for example, tightly twisting the paired conductors (which are typically insulated copper wires) in a cable, whereby different pairs are twisted at different rates that are not harmonically related, so that each conductor in the cable picks up approximately equal amounts of signal energy from the two conductors of each of the other differential pairs included in the cable. If this condition can be maintained, then the crosstalk noise may be significantly reduced, as the conductors of each differential pair carry equal magnitude, but opposite phase signals such that the crosstalk added by the two conductors of a differential pair onto the other conductors in the cable tends to cancel out. While such twisting of the conductors and/or various other known techniques may substantially reduce crosstalk in cables, most communications systems include both cables and communications connectors that interconnect the cables and/or connect the cables to computer hardware. Unfortunately, the communications connector configurations that were adopted years ago generally did not maintain the conductors of each differential pair a uniform distance from the conductors of the other differential pairs in the connector hardware. Moreover, in order to maintain backward compatibility with connector hardware that is already in place, the connector configurations have, for the most part, not been changed. As a result, many current connector designs generally introduce some amount of crosstalk.
In particular, in many conventional connectors, for backward compatibility purposes, the conductive elements of a first differential pair in the connector are not equidistant from the conductive elements that carry the signals of a second differential pair. Consequently, when the conductive elements of the first pair are excited differentially (i.e., when a differential information signal is transmitted over the first differential pair ), a first amount of signal energy is coupled (capacitively and/or inductively) from a first conductive element of the first differential pair onto a first conductive element of the second differential pair and a second, lesser, amount of signal energy is coupled (capacitively and inductively) from a second conductive element of the first differential pair onto the first conductive element of the second differential pair. As such, the signals induced from the first and second conductive elements of the first differential pair onto the first conductive element of the second differential pair do not completely cancel each other out, and what is known as a differential-to-differential crosstalk signal is induced on the second differential pair. This differential-to-differential crosstalk includes both near-end crosstalk (NEXT), which is the crosstalk measured at an input location corresponding to a source at the same location, and far-end crosstalk (FEXT), which is the crosstalk measured at the output location corresponding to a source at the input location. NEXT and FEXT each comprise an undesirable signal that interferes with the information signal. In many connector systems, a plurality of differential pairs will be provided, and differential-to-differential crosstalk may be induced between various of these differential pairs.
A second type of crosstalk, referred to as differential-to-common mode crosstalk, may also be generated as a result of, among other things, the conventional connector configurations. Differential-to-common mode crosstalk arises where the first and second conductors of a differential pair, when excited differentially, couple unequal amounts of energy on both conductors of another differential pair where the two conductors of the victim differential pair are treated as the equivalent of a single conductor. This crosstalk is an undesirable signal that may, for example, negatively effect the overall channel performance of the communications system.
Cross-connect wiring systems such as, for example, 110-style and other similar cross-connect wiring systems are well known and are often seen in wiring closets terminating a large number of incoming and outgoing wiring systems. Cross-connect wiring systems commonly include index strips mounted on terminal block panels which seat individual wires from cables. A plurality of 110-style punch-down wire connecting blocks are mounted on each index strip, and each connecting block may be subsequently interconnected with either interconnect wires or patch cord connectors encompassing one or more pairs. A 110-style wire connecting block has a dielectric housing containing a plurality of double-ended slotted beam insulation displacement contacts (IDCs) that typically connect at one end with a plurality of wires seated on the index strip and with interconnect wires or flat beam contact portions of a patch cord connector at the opposite end.
Two types of 110-style connecting blocks are most common. The first type is a connecting block in which the IDCs are generally aligned with one another in a single row (see, e.g., U.S. Pat. No. 5,733,140 to Baker, III et al., the disclosure of which is hereby incorporated herein in its entirety). The second type is a connecting block in which the IDCs are arranged in two rows and are staggered relative to each other (see, e.g., GP6 Plus Connecting Block, available from Panduit Corp., Tinley Park, Ill.). In either case, the IDCs are arranged in pairs within the connecting block, with the pairs sequenced from left to right, with each pair consisting of a positive polarized IDC designated as the “TIP” and a negatively polarized IDC designated as the “RING.”
The staggered arrangement results in lower differential-to-differential crosstalk levels in situations in which interconnect wires (rather than patch cord connectors) are used. In such situations, the aligned type 110-style connecting block relies on physical separation of its IDCs or compensation in an interconnecting patch cord connector to minimize unwanted crosstalk, while the staggered arrangement, which can have IDCs that are closer together, combats differential-to-differential crosstalk by locating each IDC in one pair approximately equidistant from the two IDCs in the adjacent pair nearest to it; thus, the crosstalk experienced by the two IDCs in the adjacent pair is essentially the same, with the result that its differential-to-differential crosstalk is largely canceled.
These techniques for combating crosstalk have been largely successful in deploying 110-style connecting blocks in channels supporting signal transmission frequencies under 250 MHz. However, increased signal transmission frequencies and stricter crosstalk requirements have identified an additional problem: namely, differential-to-common mode crosstalk. This problem is discussed at some length in co-pending and co-assigned U.S. patent application Ser. No. 11/044,088, filed Mar. 25, 2005, the disclosure of which is hereby incorporated herein in its entirety. In addition, differential-to-differential crosstalk levels generally increase with increasing frequency, and conventional 110-style cross connect systems may not provide adequate differential-to-differential crosstalk cancellation at frequencies above 250 MHz.
SUMMARY OF THE INVENTION
Pursuant to embodiments of the present invention, communications connector are provided. These connectors include a housing having an upper end and a lower end. The upper end of the housing includes a plurality of slits that define a plurality of pillars. First through fourth pairs of tip and ring insulation displacement contacts (IDCs) mounted in the housing. Each of the IDCs is substantially planar, and each IDC has an upper end that has a first slot, a lower end that has a second slot and an intermediate portion between the upper end and the lower end, the lower end being offset from the upper end. The first slot of each IDC is aligned with a respective one of the slits. The housing further includes through slots that are separated by dividers, where each of the through slots is sized to receive the upper end of a respective one of the IDCs, and each slit of the plurality of slits exposes opposed edges of the first slot of a respective one of the IDCs.
In some embodiments, the communication connector is mounted on a terminal block such that the first slot and the second slot of each IDC are on a first side of the terminal block. In some embodiments, the tip IDCs may be aligned in a first row within the housing and the ring IDCs may be aligned in a second row within the housing. The intermediate portion of each IDC may be received by the lower end of the housing. At least portions of the lower end of each of the IDCs may extend outside the housing through one or more openings in the lower end of the housing.
In some embodiments, the IDCs of each pair of IDCs may cross over each other. Moreover, the upper end of a first IDC of the first pair of IDCs may be substantially equidistant from the upper ends of both IDCs of the second pair of IDCs and may be substantially equidistant from the upper ends of both IDCs of the third pair of IDCs. The first slot and the second slot of each IDC may also be generally parallel and non-collinear.
Pursuant to further embodiments of the present invention, communications connectors are provided that include a dielectric housing that includes a first row of through slots and a second row of through slots. The housing further includes a plurality of dividers that separate respective ones of the through slots in the first row from corresponding through slots in the second row. At least four pairs of substantially planar tip and ring IDCs are mounted in the housing such that each IDC is at least partly received within a respective one of the through slots, with the tip IDCs received within the through slots in the first row of through slots and the ring IDCs received within the through slots in the second row of through slots. Each of the IDCs has an upper end that has a first wire receiving slot and a lower end that has a second wire receiving slot, the first wire receiving slot and the second wire receiving slot of each IDC being generally parallel and non-collinear. An upper end of the housing includes a plurality of slits that define a plurality of pillars, where each slit of the plurality of slits exposes inner edges of the first wire receiving slot of a respective one of the IDCs.
In some embodiments of these connectors, the upper end of a first IDC of the first pair of IDCs may be substantially equidistant from the upper ends of both IDCs of the second pair of IDCs. The first IDC of each of the pairs of IDCs may also cross over the second IDC of its respective pair of IDCs. The upper and lower ends of the IDCs of the first pair of IDCs and the upper and lower ends of the IDCs of the second pair of IDCs may also be located to self-compensate for crosstalk between the IDCs of the first and second pairs of IDCs.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a perspective view of a cross-connect system employing a connector according to embodiments of the present invention.
FIG. 2 is an exploded perspective view of a connecting block employed in the cross-connect system illustrated in FIG. 1.
FIG. 3 is a front partial section view of the connecting block of FIG. 2.
FIG. 4 is an enlarged front view of an exemplary IDC of the connecting block of FIG. 2.
FIG. 5 is a front view of the arrangement of IDCs in the connecting block of FIG. 2.
FIG. 6 is a top view of the IDCs of FIG. 5, that only shows the top end of each IDC.
FIG. 7 is a bottom view of the IDCs of FIG. 5, that only shows the bottom end of each IDC.
FIG. 8 is a perspective view of the conductive elements of a conventional plug and the connecting block of FIG. 2;
FIG. 9 is a perspective view of the conductive elements of a plug and a connecting block according to certain embodiments of the present invention;
FIG. 10 is an exploded perspective view of the plug of FIG. 9;
FIG. 11 is an end view of the plug contacts of the plug of FIG. 9;



DETAILED DESCRIPTION
The present invention will be described more particularly hereinafter with reference to the accompanying drawings. The invention is not intended to be limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the invention to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Well-known functions or constructions may not be described in detail for brevity and/or clarity.
As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Where used, the terms “attached”, “connected”, “interconnected”, “contacting”, “mounted” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise.
Communications connectors according to embodiments of the present invention will now be described with respect to FIGS. 1-11. In FIGS. 1-11, concepts according to embodiments of the present invention are implemented in a 110-style cross-connect wiring system. It will also be appreciated that the concepts discussed herein are applicable to other types of communications connectors such as, for example, a number of cross-connect systems that are known in the art that are not compatible with 110-style cross-connect wiring systems.
FIG. 1 depicts a 110-style cross-connect communications system 10, which is a well-known type of communications system that is often used in wiring closets that terminate a large number of incoming and outgoing wiring systems. The communications system 10 comprises field-wired cable termination apparatus that is used to organize and administer cable and wiring installations. The communications system 10 would most typically be located in the equipment room and may provide termination and cross-connection of network interface equipment, switching equipment, processor equipment, and backbone (riser or campus) wiring. The cross-connect communications system 10 is typically located in a telecommunications closet and may provide termination and cross-connection of horizontal (to the work area) and backbone wiring. Cross-connects can provide efficient and convenient routing and rerouting of common equipment circuits to various parts of a building or campus.
As shown in FIG. 1, the communications system 10 has connector ports 15 arranged in horizontal rows. Each row of connector ports 15 comprises a conductor seating array 14 that is commonly referred to as an “index strip.” Conductors (i.e., wires) 16 are placed between the connector ports 15. As is also shown in FIG. 1, once the conductors 16 are in place, connecting blocks 22 are placed over the index strips 14. Each connecting block 22 may include a plurality of double-ended slotted beam insulation displacement contacts (IDCs), which are not visible in FIG. 1. Each IDC may make mechanical and electrical connection to a wire and, in particular, to a wire that is surrounded by dielectric insulation. A first end of each IDC may include a pair of opposing contact fingers that strip insulation from a wire that is pressed between the contact fingers so that an electrical contact is made between the wire and the IDC. The other end of each IDC may be similarly constructed, and may likewise make mechanical and electrical connection to a wire.
As is shown in FIG. 1, a first end of each IDC in connecting block 22 forms an electrical contact with a respective one of the conductors (wires) 16 mounted in the index strip 14. The second end of each IDC may likewise make an electrical connection with a cross-connect wire (not shown). More commonly, however, as shown in FIG. 1, instead of connecting to a wire, the second end of each IDC receives a blade of a patch plug 28. The patch plug is part of a patch cord that includes a plurality of differential pairs and a plug 28 on at least one end that is used to electrically connect each differential pair to a corresponding pair of IDCs in the connecting block 22.
FIG. 1 shows four horizontal rows of six connecting blocks 22 each that are mounted on top of four index strips 14 (only a portion of one of the index strips 14 is visible in FIG. 1) in a typical terminal block 12. The spaces between the index strips 14 become troughs, typically for cable or cross-connect wire routing. The conductors 16 are routed through the cable troughs and other cabling organizing structure to their appropriate termination ports in the index strips 14.
An exemplary connecting block 22 may include a main housing 40, two locking members 48 and eight IDCs 24a-24h. These components are described below with respect to FIGS. 2-7.
FIG. 4 illustrates an exemplary IDC, IDC 24a, of the connecting block 22. IDCs are a known type of wire connection terminal. In general, a wire connection terminal refers to an electrical contact that receives a wire or a plug blade, or some other type of electrical contact, at one end thereof (or at both ends in the case of a double-slotted IDC). The IDC 24a is generally planar and formed of a conductive material, such as, for example, a phosphor bronze alloy. The IDC 24a includes a lower end 30 with prongs 30a, 30b that define an open-ended slot 31 for receiving a mating conductor, an upper end 32 with prongs 32a, 32b that define an open-ended slot 33 for receiving another mating conductor, and a transitional area 34. Each of the slots 31, 33 may be interrupted by a small brace 36 that provides rigidity to the prongs of the IDC 24a during manufacturing, but which splits during “punch-down” of conductors into the slots 31, 33. The lower and upper ends 30, 32 are offset from each other such that the slots 31, 33 are generally parallel and non-collinear. The offset distance “j” between the slots 31, 33 in the lower and upper ends 30, 32 may, for example, be between about 0.080 and 0.150 inches.
Referring now to FIGS. 2 and 3, the main housing 40, which may, for example, be formed of a dielectric material such as polycarbonate, has flanges 41 which may serve to align the connecting block 22 over the index strip 14 with which it mates. The main housing 40 includes through slots 42 separated by dividers 43, each of the slots 42 being sized to receive the upper end 32 of an IDC 24a-24h. The upper end of the main housing 40 has multiple pillars 44 that are defined by slits 46. The slits 46 expose the inner edges of the open-ended slots 33 of the IDC upper ends 32. The main housing 40 also includes apertures 50 on each side. As shown in FIG. 2, the locking members 48 are mounted to the sides of the main housing 40. The locking members 48 include locking projections 52 that are received in the apertures 50 in the main housing 40.
As is illustrated in FIG. 3, the connecting block 22 can be assembled as follows. The IDCs 24a-24h are inserted into the slots 42 in the main housing 40 from the lower end thereof. The upper ends 32 of the IDCs 24a-24h fit within the slots 42, with the slots 33 of the upper ends 32 of the IDCs 24a-24h being exposed by the slits 46 in the main housing 40. Recesses 35a of the IDCs 24a-24h engage the lower ends of respective dividers 43 of the main housing 40. Once the IDCs 24a-24h are in place, the locking members 48 are inserted into the apertures 50 such that the arcuate surfaces of the locking projections 52 engage the recesses 35b of the IDCs 24a-24h. The locking members 48 are then secured via ultrasonic welding, adhesive bonding, snap-fit latching, or some other suitable attachment technique. The interaction between the recesses 35a, 35b, the lower ends of the dividers 43, and the locking projections can anchor the IDCs 24a-24h in place and prevent twisting or rocking of the IDCs 24a-24h relative to the main housing 40 during wire punch-down.
As can be seen in FIGS. 3 and 5, once in the main housing 40, the IDCs 24a-24h are arranged in two substantially planar rows, with IDCs 24a-24d in one row and IDCs 24e-24h in a second row. As can be seen in FIG. 6 (which only depicts the upper half of each IDC) because of the “jogs” in the IDCs (i.e., the offset between the upper and lower ends 32, 30 of the IDCs), the upper ends 32 of the IDCs 24a-24d in one row are staggered from the upper ends 32 of the IDCs 24e-24h in the other row. Likewise, as can be seen in FIG. 7 (which only depicts the lower half of each IDC), the lower ends 30 of the IDCs 24a-24d are staggered from the lower ends 30 of the IDCs 24e-24h. In the embodiment of connecting block 22 shown in FIGS. 2-3 and 5, the transitional area 34 of the IDCs in opposing rows are aligned (e.g., the transition area 34 of IDC 24a is directly across from the transition area 34 of IDC 24e). In other embodiments, the transition areas 34 of opposing IDCs may be staggered.
The IDCs 24a-24h can be divided into TIP-RING IDC pairs as set forth in Table 1 below, where by convention, the TIP is the positively polarized terminal and the RING is the negatively polarized terminal. Each of the RINGS of the IDC pairs are in one row, and each of the TIPS of the IDC pairs are in the other row.











TABLE 1







IDC
Pair #
Type




















24a
1
TIP



24b
2
TIP



24c
3
TIP



24d
4
TIP



24e
1
RING



24f
2
RING



24g
3
RING



24h
4
RING










As is shown in FIG. 5, the length of each IDC 24a-24h may be a distance “k.” In an exemplary embodiment of the present invention, “k” may be about 800 mils. In the exemplary embodiment shown in FIG. 5, the distance “j” between adjacent slots of the IDCs of an IDC pair may be about 96 mils. In the exemplary embodiment shown in FIG. 5, the distance “l” between the slots of adjacent IDCs in a row of IDCs may be about 260 mils. The first and second rows of IDCs may be separated by about 70 mils.
As is best seen in FIG. 5, the resulting arrangement of the IDCs 24a-24h is one in which the IDCs of each pair “cross-over” each other. Also, in this embodiment the distance between (a) the upper end of the IDC of one pair and the IDCs of an adjacent pair and (b) the lower end of the other IDC of the pair and the lower ends of the IDCs of the adjacent pair are generally the same. As a result, the TIP of each pair and the RING of each pair are in close proximity to the IDCs of adjacent pairs for generally the same signal length and at generally the same distance. For example, as seen in FIG. 6, the upper end 32 of the RING of pair 1 (IDC 24e) is closer to the upper ends 32 of the TIP and RING of pair 2 (IDCs 24b, 24f) than is the upper end 32 of the TIP of pair 1 (IDC 24a). However, as can be seen in FIG. 7, the lower end 30 of the TIP of pair 1 (IDC 24a) is closer to the lower ends 30 of the TIP and RING of pair 2 (IDCs 24b, 24f) than is the lower end of the RING of pair 1 (IDC 24e). This pattern holds for all of the pairs of IDCs in the connecting block 22, and continues along the entire array of connecting blocks mounted on the index strip 14; in each instance, the exposure (based on signal length and proximity) of each IDC to the members of neighboring pairs of IDCs is generally the same.
As a consequence of this configuration, the IDCs can self-compensate for differential-to-common mode crosstalk. The opposite proximities on the upper and lower ends of the TIP and RING IDCs of one pair to the adjacent pair can compensate the capacitive crosstalk generated between the pairs. The presence of the crossover in the signal-carrying path defined by the IDCs can compensate for the inductive crosstalk generated between the pairs. At the same time the arrangement of the IDCs at the upper end 32 and the lower end 30 enables the IDCs to self-compensate for differential-to-differential crosstalk by locating each IDC in one pair approximately equidistant from the two IDCs in the adjacent pair nearest to it. Because both the differential-to-common mode crosstalk as well as the differential-to-differential crosstalk between pairs are compensated, the connecting block 22 can provide improved crosstalk performance, particularly at elevated frequency levels.
In a number of cross-connect systems, the electrical performance of the system may be optimized when the connecting blocks 22 are terminated with punch down wires. When the connecting block 22 is instead terminated using patch plugs 28, the electrical performance of the connecting block 22 may degrade. As a result, in some systems, it is necessary to impose more restrictive cable length restrictions or other restrictions on the cross-connect system to ensure that the performance of the cross-connect system complies with applicable standards when some or all of the connecting blocks 22 are terminated using patch plugs 28 as opposed to punch down wires.
FIG. 8 is a perspective view of the IDCs 24a-24h of a connecting block 22 mating with the contacts 124a-124h of a conventional mating patch plug 110. In FIG. 8, the main housing 40 of the connecting block 22 and the main housing 120 of the patch plug 110 are omitted to more clearly illustrate the configuration of the mating conductive elements. Unfortunately, in the configuration of FIG. 8, the level of differential-to-differential crosstalk self-compensation provided by the staggered arrangement of the plug contacts 124a-124h may be insufficient. In particular, as shown in FIG. 8, each plug contact 124a-124h includes a respective IDC region 126a-126h and a blade region 128a-128h. As the IDC regions 126a-126d of plug contacts 124a-124d are aligned in a first (lower) row, and the IDC regions 126e-126h of plug contacts 124e-124h are aligned in a second (upper) row, the differential-to-differential coupling between two adjacent pairs of the plug contacts 124a-124h in the IDC regions 126a-126h may be, to a large extent, self-compensated—i.e., the coupling between a plug contact of the disturbing pair and the like plug contact in the adjacent disturbed pair (e.g. ring 1-ring 2 or 126e-126f) and the coupling between the same plug contact in the disturbing pair and its unlike plug contact in the adjacent disturbed pair (e.g. ring 1-tip 2 or 126e-126b) are roughly of the same order of magnitude. However, the differential-to-differential crosstalk between adjacent pairs in the blade region 128a-128h of the plug contacts 124a-124h may be largely uncompensated, as the coupling between a plug contact in the disturbing pair and its unlike plug contact in the adjacent disturbed pair (e.g. ring 1-tip 2 or 128e-128b) may be significantly larger in the blade region than the coupling between the same plug contact of the disturbing pair and the like plug contact in the adjacent disturbed pair (e.g. ring 1-ring 2 or 128e-128f). The prior art plug contacts 124a-124h may also be inherently unbalanced as far as the differential-to-common mode crosstalk between two adjacent pairs due to the sizable difference in the physical proximities of the tip and ring of the disturbing pair to the adjacent disturbed pair (e.g. ring 1 is much closer to pair 2 than tip 1).
Pursuant to further embodiments of the present invention, self-compensating cross-connect systems are provided that include balanced plugs so as to have low differential-to-differential and low differential-to-common mode crosstalk when patch plugs are used in the cross-connect system. As a result, the additional cable length restrictions that may be necessary with conventional cross-connect systems when such systems are used in conjunction with patch plugs may be reduced or eliminated.
FIG. 9 depicts a connecting block 222 and a patch plug 210 of a cross-connect system 200 according to such further embodiments of the present invention. As with FIG. 8, in FIG. 9 the main housing 240 of the connecting block 222 and the main housing 220 of the patch plug 210 are omitted to more clearly illustrate the configuration of the mating conductive elements. FIG. 11 is an end view of the plug contacts of FIG. 9.
As shown in FIG. 9, the IDCs 224a-224h that are included in the connecting block 222 may be identical in design and configuration to the IDCs 24a-24h discussed above. As such, further discussion of IDCs 224a-224h will be omitted. The plug 210 includes eight plug contacts 224a-224h. Each plug contact includes a respective IDC region 226a-226h and a respective blade region 228a-228h. In addition, each plug contact 224a-224h includes a respective cross-over segment 227a-227h (only crossover segments 227e-227h are labeled in FIG. 9 as crossover segments 227a-227d are mostly obscured by crossover segments 227e-227h, respectively). As discussed below, these cross-over segments 227a-227h may be configured to provide self-compensating plug contacts.
In particular, as shown in FIG. 9, the cross-over segments 227a-227h may be used to reverse the respective positions of the respective IDC regions 226a-226h on each pair of plug contacts 224a-224h. For example, referring to FIG. 8 and focusing on the plug contacts 124a (tip 1) and 124e (ring 1) which form pair 1, it can be seen that in the conventional design, the IDC region 126e of contact 124e (ring 1) is closer to the plug contacts 124b, 124f of pair 2 than is the IDC region 126a of contact 124a (tip 1). In contrast, as shown in FIG. 9, in the plug 210 according to embodiments of the present invention, the IDC region 226e of contact 224e (ring 1) is further from the plug contacts 224b, 224f of pair 2 than is the IDC region 226a of contact 224a (tip 1). By reversing the respective positions of the IDC regions of the plug contacts of each pair of plug contacts it may be possible to provide a self-compensating plug that compensates in the IDC regions for differential-to-common mode crosstalk that is generated in the blade regions of the plug contacts. Moreover, as shown in FIG. 9, the crossover segments 227a-227h may be configured to provide coupling of opposite polarity to the differential-to-differential crosstalk generated in the plug blades, as the coupling between a plug contact in the disturbing pair and its like plug contact in the adjacent disturbed pair (e.g. ring 1-ring 2 or 227e-227f) may be significantly larger in the crossover segment region than the coupling between the same plug contact of the disturbing pair and the unlike plug contact in the adjacent disturbed pair (e.g. ring 1-tip 2 or 227e-227b). Thus it may be possible to configure the crossover segments 227a-227h of the plug contacts 224a-224h to provide a self-compensating plug that compensates in the crossover segments 227a-227h for differential-to-differential crosstalk that is generated in the blade regions 228a-228h of the plug contacts 224a-224h. 
FIG. 10 is a perspective view of the patch plug 210 of FIG. 9. The patch plug 210 may be part of a patch cord that includes a cable (not shown) and the patch plug 210. The cable may comprise four differential pairs of conductors that are twisted together in a manner to reduce crosstalk as is known to those of skill in the art. The cable may also include a separator that separates at least one of the twisted differential pairs from another of the twisted differential pairs, and a jacket which encloses the differential pairs and the separator. A core twist may be applied to the twisted differential pairs.
The patch plug 210 may include a dielectric housing 220. The dielectric housing may be formed of two pieces which snap together and capture plug contacts 224a-224h. The housing may be molded from a polycarbonate resin or other suitable material. The housing may include slots or other structure that is configured to receive and hold plug contacts 224a-224h in place. The plug contacts 224a-224h may be factory-installed and firmly embedded in the housing. Each conductor of the four differential pairs in the cord terminates into a respective one of the IDCs provided at the respective IDC regions 226a-226h of the plug contacts 224a-224h. The conductors of the differential pairs are connected so that the differential pair relationship in the cable is maintained in the plug. The housing 220 may also include other conventional features such as a strain relief mechanism, a retainment latch, alignment flanges and the like which are known to those of skill in the art and thus will not be discussed further herein.
In the particular embodiment of the patch plug 210 of FIGS. 9-10, the improved differential-to-differential and differential-to-common mode crosstalk performance is provided by designing the plug contacts of each differential pair to cross over each other via the respective cross-over segments 227a-227h, with each crossover segment confined to the same plane as the respective IDC portion. It will be appreciated, however, in light of the present disclosure that, in other embodiments, the cross-over segments 227a-227h may be implemented in numerous different ways and with a wide variety of different shapes and/or configurations that would provide opposite polarity coupling relative to the differential to differential crosstalk generated in the plug blades.
Those skilled in this art will appreciate that connecting blocks, IDCs, patch plugs and plug contacts according to embodiments of the present invention may take other forms. For example, the components of the connecting block and plug housings may be replaced with a wide variety of different housing shapes and/or configurations. The number of pairs of IDCs and/or plug contacts may differ from the four pairs illustrated herein. Likewise, the IDCs and/or plug contacts may be unevenly spaced. The IDCs may, for example, lack the brace 36 in the slots that receive conductors. Also, the IDCs may lack the engagement recesses or may include some other structure (perhaps a tooth or nub) that engages a portion of the mounting substrate to anchor the IDCs. Also, IDCs as described above may be employed in connecting blocks of the “aligned” type or “staggered” type having no pair crossovers discussed above or in another arrangement. Furthermore, the upper sections 32 and the lower sections 30 of the IDCs may be physically separated form each other and mounted to a printed wiring board in arrays similar to FIGS. 6 and 7, with plated through-holes and traces on the board completing the connections between them. Likewise, the plug contacts could also be implemented using printed circuit boards to effect the crossover. Such printed circuit board implementations would still be considered to comprise “plug contacts” as that term is used herein.
In some embodiments of the present invention, the connecting block 22 may also include one or more parasitic conductive loops as disclosed and described in detail in co-pending U.S. patent application Ser. No. 11/369,457, filed on Mar. 7, 2006, the contents of which are incorporated by reference herein as if set forth in its entirety.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.

## Claims

1. A communications connector, comprising:
a housing having an upper end and a lower end, the upper end of the housing including a plurality of slits that define a plurality of pillars;
a first pair of tip and ring insulation displacement contacts (IDCs) mounted in the housing;
a second pair of tip and ring IDCs mounted in the housing;
a third pair of tip and ring IDCs mounted in the housing;
a fourth pair of tip and ring IDCs mounted in the housing;
wherein each of the IDCs is substantially planar;
wherein each of the IDCs has an upper end that has a first slot, a lower end that has a second slot and an intermediate portion between the upper end and the lower end, the lower end being offset from the upper end;
wherein the first slot of each IDC is aligned with a respective one of the slits; and
wherein the housing further includes through slots that are separated by dividers, where each of the through slots is sized to receive the upper end of a respective one of the IDCs, and wherein each slit of the plurality of slits exposes opposed edges of the first slot of a respective one of the IDCs.

2. The communications connector of claim 1, wherein the communication connector is mounted on a terminal block such that the first slot and the second slot of each IDC are on a first side of the terminal block.

3. The communications connector of claim 1, wherein the tip IDCs are aligned in a first row within the housing and the ring IDCs are aligned in a second row within the housing.

4. The communications connector of claim 3, wherein the intermediate portion of each IDC is received by the lower end of the housing.

5. The communications connector of claim 4, wherein at least portions of the lower end of each of the IDCs extend outside the housing through one or more openings in the lower end of the housing.

6. The communications connector of claim 5, wherein the IDCs of each pair of IDCs cross over each other.

7. The communications connector of claim 1, wherein the upper end of a first IDC of the first pair of IDCs is substantially equidistant from the upper ends of both IDCs of the second pair of IDCs and is substantially equidistant from the upper ends of both IDCs of the third pair of IDCs.

8. The communications connector of claim 3, wherein the first slot and the second slot of each IDC are generally parallel and non-collinear.

9. A communications connector, comprising:
a dielectric housing that includes a first row of through slots and a second row of through slots, and a plurality of dividers that separate respective ones of the through slots in the first row from corresponding through slots in the second row;
at least four pairs of substantially planar tip and ring insulation displacement contact (IDCs) mounted in the housing, wherein each IDC is at least partly received within a respective one of the through slots, with the tip IDCs received within the through slots in the first row of through slots and the ring IDCs received within the through slots in the second row of through slots;
wherein each of the IDCs has an upper end that has a first wire receiving slot and a lower end that has a second wire receiving slot, the first wire receiving slot and the second wire receiving slot of each IDC being generally parallel and non-collinear;
wherein an upper end of the housing including a plurality of slits that define a plurality of pillars; and
wherein each slit of the plurality of slits exposes inner edges of the first wire receiving slot of a respective one of the IDCs.

10. The connector block of claim 9, wherein the upper end of a first IDC of the first pair of IDCs is substantially equidistant from the upper ends of both IDCs of the second pair of IDCs.

11. The connector block of claim 10, wherein the first IDC of each of the pairs of IDCs crosses over the second IDC of its respective pair of IDCs.

12. The-connector block of claim 11, wherein the upper and lower ends of the IDCs of the first pair of IDCs and the upper and lower ends of the IDCs of the second pair of IDCs are located to self-compensate for crosstalk between the IDCs of the first and second pairs of IDCs.