CA2134697C - Connector for unshielded twisted wire pair cables - Google Patents

Abstract

Disclosed is an electrical connector for multi-wire cables. A first section of the connector includes a portion for mating with another connector. Asecond section of the connector includes conductors in an essentially side-by-side alignment to produce crosstalk having a polarity opposite to that of the mating section.

Description

21346~7 CONNECTOR FOR UNSHIELDED TWISTED WIRE PAIR CABLES
Back~round of the L.~..Lo..
This invention relates to electrical com~eclol~.
Connectors of the type known as mini~tllre ribbon style or telco 5 connectors are typically used to provide electrical contact between cables including a plurality of unshielded twisted wire pairs. Such c~ nnect rs usually comprise aninsulative housing which includes two rows of contacts. One end of the contacts provides either a male or female mating section for electrical connection with another conne~;~ol. The opposite ends of the contacts are formed into in~ul~til)n 10 displacement contacts which pierce the insulation of the twisted wire pairs to provide electrical contact thereto. The wire pairs are ~tt~chçd so that each wire in a pair is coupled to a dirrt;lci.lt row of the array of contacts, and so that the wires rest in an essenti~lly horizontal direction (i.e., parallel to the contacts). (See, e.g., U.S. Pat.
No. 4,350,404-) It has also been suggested in some connector structures to have cable wire attached to in~ul~til~n displacement contacts in a vertical direction (i.e., perpendicular to the contacts). (See, e.g., U.S. Patent No. 4,066,316.) Standards for crosstalk in connectors are becoming increasingly stringent. For example, in category 5 of the proposed EIA/TIA TSB40 Standard, it20 is required that a 25 pair ribbon cable connector exhibit near-end crosstalk which is less than 40 dB at 100 MHz using the standard power sum ..~ea~u~cll-ent. However, the miting section of the typical connector by itself does not meet this requi~.,...ent.
Thus, reducing crosstaL~ in other portions of the conne,-lo~ is not sufficient to provide a connector which conro..ns to this new ~,ro~ n-e standard.
25 Summary of the Invention The invention is an electrical connector compricing an insulative housing and a plurality of conductive members mounted therein. In one section, one end of each member is adapted for mating with another connec~or and in a second section an opposite end is adapted for providing electrical contact. The second 30 section of the c-)nnector includes conductors formed in side-by-side ~ nment to provide crosstaL~c of a polarity which is opposite to that produced by the first section.
Brief Description of the Drawin~
These and other features of the invention are delinçated in detail in the following description. In the drawing:

~1~46~97 FIG. 1 is a top plan view, partly cut away, of a connector in accordance with an embodiment of the invention;
FIG. 2 is a cross-sectional view of the connector along line 2-2 of FM. l;
FIG. 3 is an end view of a portion of the connector of FIG. l;
FIG. 4 is a view of a portion of the COnlle~;101 along lines 4-4 of FIG. 2;
FM. 5 is a view of a portion of the connector along lines 5-5 of FIG. 2;
FIG. 6 is a top plan view, partly cut away, of a connector in accordance with a further embodiment of the invention;
FIG. 7 is a cross-section~l view of the co~ ol taken along line 7-7 of FM. 4;
FIG. 8 is an end view of a portion of the connector of FIG. 4;
FIG. 9 is a cross-sectional view of a connector in accordance with a still further embodiment of the invention; and FIG. 10 is a cross-sectional view along line 10-10 of FIG. 9.
It will be appreciated that, for purposes of illustration, these figures are not n~ress~rily drawn to scale.
Detailed Description As illustrated in FIGS. 1-3, the connector, 10, in accordance with one 20 embodiment, includes an ins~ ting housing, 11, typically made of plastic. Mounted within the housing is an array of conductive members, e.g., 12, 13, 70 and 71. The conductive members are typically mounted within the housing in two rows. Each conductive member, e.g., 12, in~hl(les two opposite end portions. One end portion, e.g., 14, of each conductive member is shaped so as to form a mating section which 25 is adapted for receiving and electrically contacting a similar plug-type connector (e.g., FIGS. 6-8). The opposi~ end portions, e.g., 15, are shaped to form in~ tiQn displ~rement contacts for electrically contacting wires, e.g., 16, from a cable, 17, which typically includes a plurality of twisted wire pairs. The conductive members are arranged so that opposite members, e.g., 12 and 13, in different rows contact the 30 wires (16 and 18) of the hvisted pairs (see FIG. 3).
It will be noted in this embodiment that the conductive members (e.g., 12 and 13) are bent inward so that the vertical distance, _, between the two rows of con-1uctive elements at the contact portions (e.g., 15) is less than the vertical t~nce~ S, at the mating portions (e.g., 14). Typically, _ will be less than one-half 35 of S. This configuration is advantageous for reasons to be discussed.

~134697 _ -- 3 --Also mounted within the housing, 11, adj~cent to the contact portions (e.g, 15) of the conductive elements (e.g., 12 and 13) is a mandrel, 20, as shown in FIGS. 1 and 2. (The mandrel has been omitted from the view of FIG. 3 for purposes of illustrating the placement of the contact portions of the conductive elem~nt~.) The 5 mandrel, 20, is made of an inml~ting m~tçri~l such as plastic, and is typically rect~ng~ r in cross section, but could be a variety of shapes. The mandrel extends essenti~lly the full length of the com~ or and, desirably, includes a pair of slots 21 and 22 to accommodate the contact portions (e.g., 15) of both rows of the conductive elern~nt~ (e.g., 12 and 13). The top, bottom and left-hand surfaces of the mandrel as 10 viewed in FIG. 2 may also include grooves, e.g., 23, for positioning wires from each contact portion.
The width, w, and other (limen~ions of the mandrel, 20, play an important part in reducing the crosstaL~ of the connector. It is known that the mating sections of the conductive elements will produce a certain amount of crosstaL~ in the 15 form of an induced voltage with one polarity, hereinafter referred to as "positive"
crosstaLIc. However, the wires, e.g., 16 and 18, coupled to the contact portions are aligned side-by-side on the surface of the mandrel, 20, for a certain pre~let~,....in~l length (w+x+y+z). This alignment will produce a crosstalk in the form of inducedvoltage of the opposite polarity to that of the mating section crosstalk ("negative"
20 crosstaLI~). This change in polarity of crosstaLk is due to the fact that the wire pairs will all be aligned side-by-side in a single plane over the mandrel (e.g., pair 16, 18 is in the same plane as pair 72, 73 in FIG. 4), while the pairs of conductive members coupled to each wire pair (e.g., pair 12, 13 CQ~ f~1 to 16, 18 and pair 70, 71 connected to 72, 73) will be in essenti~lly parallel planes having a dirr."~ t 25 olienkt~ion in the mating section of the connector (e.g., as shown in FIG. 5).
For each section of the connector, the inductive crosstaL~, X~ (in volts), ~w~en any two pairs of conductors can be calculated according to the expression:
X~ = / [M"~ - Mad + Mbd--Mb~

30 where I is the current in one pair of c-~n-luctors and M a~c ~ M ad, M bd, M bc are the mutual inductances from one conductor to another (i.e., ~sl-ming con-luctors a and b in one pair have current, I, applied thereto and conductors c and _ in the other pair have an inrluce~ voltage).

213~697 The mutual in~nct~nce terms, M~y (in nH), can be applu~d,nated according to the expression:

Mxy =SL ln 1 +~¦1 + 1 -~1 +r2 +r (2) r r S where L is the conductor length in the section (in inches) and r is the ~ t~nce from con~nctor x to conductor y divided by the con~nctor length (L).
For each section of the conneclor, the c~r~itive crosstaLIc, Xc (in volts), between any two pairs of conductors may be calculated according to the e~ ,ssion:

Xc = d /dt (z) (Ccm ) (3) 10 where V is the voltage on one pair of conductors, Cm is the mutual c~p~cit~n~e betw~ conductor pairs, and Z is the impedance terrnin~ting both the near-end andthe far-end of the idle pair.
The capacitance value (Cm) is a function of the conductor shapes, spacingS and lengths as well as the dielectric constants of the materials ~ulluunding lS the conductors. Formulas are available for simple geometries (see, e.g., Charles S.
WaLker, C~r~cit~nre, ~n(lnct~nce and Crosst~L~c Analysis, (Artech House, 1990), pp. 66-71.
The near end crosstaLlc in~1nce~l in an idle pair of con-1nctors in any section by another pair of con~nctors is the sum of the inductive and cap~citive20 crosst~Llc. The total near-end crosstaLlc in an idle pair in a section is c~ ul~te~ by the standard power sum method.
The.~;fole, each section of the connector will exhibit a dirr~ . t amount of crosstaL~ The value of the crosstaLk in the mandrel secdon will be negative when calculated according to the above. By choosing applùpliate values for the 25 dimensions (w, x, y) of the mandrel and for the wire length section (z), the crosst~Lk in this section can be made to nearly cancel out the positive crosstaLk of the conductive members.
The applupliate ~limen~ions may also be dete.-nilled empirically by measuring the crosstaLk for various ~lim~n5ion~.

213~697 Typically, the crosstalk in the conductive members was 39.5 dB
between adjacent pairs at 100 MHz, while the crosstalk of the mandrel section was 40 dB of opposite polarity.
An ap~ iate choice of the ~limen~ion~ w, x, y and z, will Ih~,lefolG
S tend to cancel out the crosstalk produced by the conductive members. Ren~ling the conductive members to place the members vertically closer together at the contact portions (making _ less than S in FIG. 2) is advantageous in reducing crosstalk of the conductive members and thereby minimi~ing the predet~ ....in~1 distance required for side-by-side alignment of the wires. This is especially i~ ,w ~lt where the 10 contributions in crosstalk by con~ cto pairs beyond pairs adjacent to the idle pair contribute signifi~ntly to overall crosstalk. In a typical example, the distance _ would be ~ illlately 1.75 cm in accordance with the equations above. In general, distances in the range 1.0-2.0 cm should be useful.
A hood element, 30, snaps onto the housing, 11, to secure the mandrel, 15 20, in the housing and to provide a colllp~lllent for the twisted wire pairs 31. The wire pairs exit the hood where they are formed into one or more cables 17. The hood element is also, typically, made of plastic.
FIGS. 6-8 show an alternative embodiment of the invention. Again, an insulative housing, 40, includes two rows of conductive elements, e.g., 41 and 42, 20 mounted therein. As before, each conductive element inrludes a mating portion, 43, at one end and an insulation displacement contact portion, 44, at the opposite end.
One distinction here is that the mating portions form a plug connector which can fit, for example, into the receptacle connector of FIGS. 1-5. However, this embodiment can also be formed into a receptacle conneclo- by a~pl~liately shaping the mating 25 portions as in FIGS. 1-2.
A further ~ tinction lies in the fact that the spacing S' between mating portions of the dirÇ~ t rows is essentially equal to the spacing d' between the contact portions of the two rows.
In this emb~iment, the mandrel, 50, includes two parts, 51 and 52, with 30 nnd~ ting surfaces which are complementary so that the parts fit together while allowing a meandering path for the wires, e.g., 60 and 61, from the twisted pair cable (not shown). One wire, e.g., 60, from each pair is conne~;t~d to a conductive member, e.g., 42, in the bottom row, and the other wire, e.g., 61, from the pair is connected to a conductive member, e.g., 41, in the top row. (See also FIG. 8 where 35 the mandrel has been removed for purposes of illustration.) 213~697 As in the previous embodiment, the wires will extend for a predetermined length in a side-by-side alignment dçterminP~I by e~pe~ ellt or c~ tPd from the equations above in order to co..~-n~te for the crosstalk gellel ~led by the mating portion of the conductive members. In -this embodiment, 5 the predete~ led length is established by the path length of the llnd~ ting surfaces of the two parts 51 and 52. In a particular example, the path length is apl)luAin~ately 3.3 cm, but in general would range from 2.5-4.0 cm. The contact portions, e.g., 44, of the conductive members, e.g., 41 and 42, have appl.J~ tely the same vertical spacing as the mating portions, e.g., 43 (i.e., S'=d') to allow for the bending of the 10 wires (60, 61) between cont~ct~. This spacing is made possible by the increased path length of the wires over the mandrel surface.
As before, a hood (not shown) snaps onto the housing in order to hold the mandrel and the twisted wire pairs.
While the invention has been described for cables inclu(ling twisted wire 15 pairs, it is also advantageous for any cable inch1-1ing bql~nced wire pairs. Also, while the wires are preferably perpendicular to the conductive members to produce a short connection, the invention may also be used where the wires are oriented atother angles, including the case where the wires are parallel to the conductive members at the point of contact.
While the invention is optimized by keeping the wires in side-by-side ~lignment over the mandrel surface, some mic~lignment or staggering of the wirescould still result in s~-ffi~i~P-nt negative crosstaL~c to be advantageous. In general, however, no wire should have a vertical distance (as viewed in FIG. 4) from any other wire which is greater than half the distance from the cen~lline of one pair to 25 the centerline of the ~dj~ent pair.
Further, the wires need not be equally spaced from each other as shown in FIG. 4. Rather, varying the distance between wires can produce a greater negative crosstalk. In general, it is advantageous to have a distance between wires in a pair (e.g., 16, 18) at least equal to one-half the ~ t~nce from the cen~ e of one pair 30 (16, 18) to the centerline of an adjacent pair (72, 73).
It will also be appreciated that the stub length of each wire (dimen~ion Z
of FIG. 2) can also be used to control the amount of negative crosstalk.
Finally, it should be understood that the invention in its broadest form is directed to providing a section of a connector which has a crosstaLk of a polarity 35 opposite to that of the mating portion of the connector. The use of a mandrel in that "compensation" section to keep the wires in side-by-side alignment is an advantageous embodiment of that principle. However, a similar effect could be produced as illustrated by the connector shown in FIGS. 9 and 10, where elementssimilar to FIGS. 1-5 are similarly numbered. Hence, while a mandrel, 20, is still used to connect the wires, e.g., 16, to their applopliate con-luctive members, e.g., 12, 5 the conductive members themselves, e.g., 12, 13, 70 and 71, are bent so that they are in side-by-side alignment for some predetermined fiist~n~e (w). In this example, the conductive members (e.g., 12 and 13) coupled to each wire pair are insert moldedinto se~ t; plastic members, 24 and 25, which plastic members are held together in the conntc~or housing 11. As illustrated in FIG. 10, the conductive members need10 not be in perfect side-by-side alignment to produce a suffi~ nt negative crosstalk as discussed regarding the previous embodiments. Alternatively, all the con(lllctive members could be molded into a single plastic member. It will also be appreciated that all the conductive members (12, 13, 70 and 71) could be deposited on a surface of a printed circuit board in place of the plastic members 24 and 25. In fact, the 15 mandrel, 20, and wires, e.g., 16, could be elimin~tecl entirely so that the invention provides a means of mounting a connector to a printed circuit board while the conductive members on the board have a specified length and spacing to essentially cancel the crosstaL~ produced by the mating sections as previously discussed.
Nevertheless, it will be understood that the term "conductors" in the 20 claims is intended to include conductive members (such as 12, 13), wires (such as 16, 18), and conductive members deposited on printed circuit boards within theirscope.
Various additional modifications will become appa~t to those skilled in the art. All such variations which basically rely on the teachings through which 25 the invention has advanced the art are plu~lly considered within the scope of the inventlon.

Claims (9)

Claims:

1. An electrical connector for contacting a cable including a plurality of wires comprising:
an insulative housing; and a plurality of conductive members mounted within the housing, one end of each member in a first section being adapted for mating with another connector and an opposite end of each member in a second section being adapted for providing electrical contacts to a wire, the second section including conductors positioned essentially in side-by-side alignment to provide crosstalk of a polarity which is opposite to that produced by the first section.

2. The connector according to claim 1 wherein the conductors are wires, and further comprising a mandrel in close proximity to one end of each member and having a surface of predetermined length on which each wire is laid so that each wire is in side-by-side alignment for the predetermined length.

3. The connector according to claim 2 wherein the conductive members are arranged in at least two rows.

4. The connector according to claim 3 wherein the distance between the contact ends of the members of the two rows is less than the distance between the mating ends of the members of the two rows.

5. The connector according to claim 3 wherein the distance between the contact ends of the members of the two rows is essentially equal to the distancebetween the mating ends of the members of the two rows.

6. The connector according to claim 2 wherein the mandrel comprises two parts, and the surface of predetermined length comprises an undulating surface of one of the parts which is adjacent to a complementary undulating surface of the other part.

7. The connector according to claim 2 further comprising a hood element mounted to the housing and enclosing the mandrel.

8. The connector according to claim 2 wherein the mandrel surface includes a plurality of grooves for aligning the wires with associated conductive members and maintaining spacing between the wires.

9. The connector according to claim 2 wherein the wires comprise a plurality of twisted wire pairs, and the spacing between wires in a pair is at least equal to one-half the distance between centerlines of adjacent pairs.