EP0789939B1

EP0789939B1 - Electrical plug conector

Info

Publication number: EP0789939B1
Application number: EP95932408A
Authority: EP
Inventors: Jess B. Ferrill; Kevin Hudson Snead
Original assignee: Whitaker LLC
Current assignee: Whitaker LLC
Priority date: 1994-10-31
Filing date: 1995-09-08
Publication date: 1999-06-23
Anticipated expiration: 2015-09-08
Also published as: CN1171172A; ES2135088T3; AU688593B2; JP4070805B2; CN1312601A; CN1161864C; CN1076891C; AU3546195A; DE69510464T2; DE69510464D1; WO1996013878A1; EP0789939A1; JPH10508146A; KR970707607A

Description

This invention is directed to the enhancement of an electrical connector such as a modular plug, by use of a load bar insert to improve performance through a reduction in crosstalk. A current standard or performance level used today is identified as Category 5 products where operating frequencies may be 100 MHZ or higher. While the invention has diverse application for the preparation and alignment of wires to be terminated within a connector, it has particular utility with the loading of modular plugs which often must be terminated in the field by technicians, or in a small factory operations manually. A first approach introduced several years ago was the use of a wire organizer, where the discrete wires were first loaded into such wire organizer to align and position the wires for eventual entry into the connector. However, problems still persisted with the use of such organizers, as free ends of the wireless still had to be directed to an assigned passageway in the connector, and stubbing of the ends could result.

In order to overcome these problems and to facilitate handling of a plurality of discrete wire conductors, methods were developed for bonding a plurality of conductors to form a unitary ribbon type cable. EP-A-0315763 discloses a bonding method which includes the use of a first fixture for aligning the ends of a plurality of conductors, and a bonding device for applying heat and pressure to bond the conductors to an intermediate foil strip. EP-A-0226779 discloses another method wherein a plurality of conductors is received by a positioning die and fed through the die to be held firmly against a carrier film. The film and the conductors pass through a heating zone wherein high temperatures cause the conductors and the carrier film to fuse. FR-A-2266430 also discloses a method for bonding a plurality of conductors to a carrier film.

Each of these references teaches that the plurality of conductors should be bonded to a separate carrier film or substrate. The carrier film adds to material expense and is not required for electrical performance. It is an advantage of the invention that a ribbon type cable is produced without using carrier film.

The invention includes an electrical connector housing with the features of claim 1. To bond and align the plurality of discrete insulation jacketed conductors for the connector a method is included. The method comprises the steps of:

a) aligning said plural conductors in side-by-side fashion on a first fixture, where said fixture includes a plurality of heating elements, with each heating element arranged to the contact the insulation jackets of an adjacent pair of said conductors,

b) by aligning a second fixture of comparable design and function in sandwich fashion to the opposite sides of said insulation jacketed conductors, and

c) applying electrical current to said heating elements to effect a localized melting and bonding of the insulation jackets of adjacent conductors to one another, thereby forming a ribbon type cable for ease of handling termination.

To enhance the performance of the connector, a load bar insert is provided down stream of the bonded wire ends. The load bar insert is characterized by having an upper surface and a lower surface to space or separate selected pairs of the conductors. Within the limits of the connector or plug housing, the insert or spacing maximizes the separation of the selected pairs and arranges them in plural planes before being realigned upstream into a common plane for bonding and terminating at the conductor terminating end. The load bar insert includes grooves in the upper and lower surfaces of the insert.

The invention will now be described by example with reference to the accompanying drawings in which:

FIGURE 1 is an exploded perspective view of an electrical connector, such as a modular plug, for example, illustrating the use of a performance enhancing load bar insert.

FIGURES 2 to 4 are transverse sectional views illustrating the sequence for bonding discrete wires to form a uniform ribbon cable according to this invention.

FIGURES 5 and 6 are lateral sectional views corresponding to the sequences illustrated in Figures 2 and 3, respectively.

FIGURE 7 is a lateral sectional view of the assembled modular plug illustrated in Figure 1.

FIGURE 8 is a sectional view taken through line 8-8 of Figure 7.

FIGURE 9 is a perspective view of the load bar insert of Figure 1, illustrating a pre-loading condition thereof, with the discrete conductors poised for lacing therein.

FIGURE 10 is a sectional view of a prior art cable, taken along line 10-10 of Figure 1, showing plural conductors prior to a planar arrangement thereof for entry into the load bar insert of Figure 9.

FIGURE 11 is a sectional view of a preferred load bar insert of this invention, taken along line 11-11 of Figure 1.

FIGURE 12 is a sectional view, taken along line 12-12 of Figure 1, showing the realigned conductors in a planar relationship for entry into a modular plug, for example, prior to termination therein.

Figure 1 illustrates a prime example of how the invention can simplify the loading and termination of a modular plug. A typical electrical connector 10, as shown in Figure 1, comprises an insulating housing 12 formed with an open end 14 for receiving a multi-wire electrical cable 16, a terminating end 18 communicating with a row of cable wire receiving passageways. The passageways further communicate with an internal cavity 20 opening into end 14. By way of further understanding, the multi-wire electrical cable 16 is characterized as twisted pair cable, where preferably selected pairs of wires are twisted together. That is, a typical cable for an 8-position modular plug will reveal four twisted pairs of insulated wires. By way of further example, under specification TIA/EIA-568A, a preferred pairing arrangement of conductors or wires for the modular plug terminal numbers is as follows: 1-2, 3-6, 4-5, and 7-8.

As noted previously, this invention has utility in the loading of fine wires to electrical connectors, with the assistance of a loading bar insert or wire organizer, as hereinafter explained. Nevertheless, the approach lies in the use of this invention with a loading bar insert 22, and illustrated in Figure 1 and later Figures. The further discussion insofar as it relates to the bonding procedure, will be directed to the load bar insert of Figures 1 and 7. This insert, molded or formed of a rod or shaped body, includes upper and

lower surfaces

24, 26, respectively, a back 28, and a tapered or divergent forward surface 30 directed to the cable receiving passageway 32 underlying the conductor terminating blades or terminals 23, see Figure 7. Along the respective upper and

lower surfaces

24, 26, are pairs of slots or

grooves

34, 36, respectively, into which selected pairs of wires 38 are laced or received. To carry on with the pairing arrangement above, pairs 3-6 and 7-8 are seated within upper slots 34, while the remaining two pairs are seated within lower slots 36. Note further that the upper slot containing pair 3-6 includes an end divider 40, to separate and align the wires into their numerically assigned position for termination.

Once the selected pairs are positioned within the insert, the discrete, insulated wires 1 to 8 are positioned between a sandwich like bench fixture 44 illustrated in Figures 2 to 6, a preferred practice in bonding the discrete wires. In any case, the pair of fixtures may each comprise a planar body 46 having plural, parallel resistance heating elements 48 arranged along the mating surfaces 50. As best seen in Figures 5 and 6, the opposite surface 52 includes means 54 for supplying electric current to the heating elements 48 to effect heating thereof. The heating elements 48 are positioned to lie between adjacent side-by-side wires, and to the outside thereof, see Figure 3. In the illustrations of Figures 2 to 4, if the number of wires is "n", the number of heating elements is "n + 1". With the respective fixtures positioned in a compressive relationship to the discrete wires, note the direction arrows of Figure 3, electrical current may be applied to the heating elements 48 by means 54 to effect melting and bonding of the insulated wires into a unitary ribbon cable at the end thereof. That is, the respective fixtures 44 are brought together to trap and locate the discrete wires exactly on the preferred 1.016 mm (≙ 0.040") centerlines, where the heating elements 48, such as nichrome heating wires, are also spaced on 1.016 mm (≙ 0.040") distances. By this arrangement, including the outermost heating elements, the heating elements act as miniature "V" blocks. With the fixtures separated, note the direction arrows of Figure 4, it will be seen that the wires are bonded, and that a scalloped profile 55 is revealed. Thereafter, the bonded wires are trimmed laterally through the scalloped profile to present a unitary member for insertion and termination within the modular plug. This profile offers a further advantage to the insertion and termination procedure, as hereinafter explained. Another advantage in the use of this type of fixture is the rather quick cool down of the system which allows for a rapid turnaround in repeating the operation with a new and different set of wires.

Figures 7 and 8 illustrate an inserted and preterminated unitary member in a modular plug, where the bonded wires are positioned under the plural terminating blades 23. The passageways 32 into which the bonded wires are received are typically a series of circular communicating sections, where the upper and lower surfaces are scalloped 60, and the sections are separated by two spaced apart opposing ribs 62. With a conventional discrete wire insertion, where the wire is not precisely aligned with the passageway, stubbing can occur. However, with the present invention, where the bonded web between adjacent wires has been modified by the newly impressed profile 55, stubbing problems are greatly minimized. Also, by reshaping or changing the wire profile, it is now possible to use larger diameter wires than heretofore possible. That is, the molded impressions from the scalloped profile 55 create clearances which ease the insertion process and even allow the use of wires exceeding 1.016 mm (≙ 0.040") diameter, for example.

In accordance with a preferred procedure for practicing this invention, a fixture was prepared using a printed circuit board with nine SST wire loops arranged on 1.016 mm (≙ 0.040") centerlines, the same spacing as the insulated wires, in parallel fashion. With a pair of such fixtures arranged in sandwich fashion to eight insulated wires, a current of 7 to 10 amperes at from 5 to 2 seconds was applied to the SST wire loops to effecting bonding of the insulated wires. After trimming, the bonded wires were readily inserted into a modular plug.

Alternate procedures are available to effect bonding of the wire ends. For example, while the wires are positioned in side-by-side fashion in a suitable fixture, an adhesive or tape may be applied to such ends to present a unitary ribbon cable at least at the end thereof. However, these alternate approaches do not offer the advantage of reshaping the wire ends as will be found in the heat bonding procedure.

Turning now to the load bar insert before continuing with a description of this feature, some brief background may be helpful. As known in the art, the multi-wire electrical cable 16, shown in section in Figure 10, is characterized as twisted pair cable, where preferably selected pairs of wires 38 are twisted together. That is, a typical cable for an 8-position modular plug will reveal four twisted pairs of insulated wires. By way of further example, under specification TIA/EIA-568A, a preferred pairing arrangement of conductors or wires for the modular plug terminal numbers are as follows: 1-2, 3-6, 4-5, and 7-8. This will be discussed in more detail hereinafter. Nevertheless, it should be noted that under prior art practices it was believed that in the preparation and termination of the wires in a modular plug, the "1/2 inch untwist" rule had to be followed. That is, the twisted pairs had to remain twisted except for about 1/2 inch that is about 12.7 mm of the end of each of wire to effect termination. It was discovered that such rule for modular connectors can be violated by the practice of the optional feature hereof without suffering an increase in Near End Crosstalk (NEXT). A critical factor is that the physical separation of the interfering pairs (primarily the 3-6 pair which is split around the 4-5 pair in the center of the plug) is more important than maintaining a tight twist. Crosstalk is inversely proportional to the distance between the interfering wires.

Continuing with the remaining Figures, Figure 9 illustrates a load bar insert 22, adapted to be slidable received through opening 14 within the housing 10. This insert, formed from a dielectric material, was described above. Note by providing for the upper and lower slots, separation of the wires is maximized within the housing 10. Further, by providing for the forward or diverging surface 30, the respective wire pairs along the upper surface 24 are in multiple planes before returning to a single plane, as shown in Figure 12. These factors contribute significantly to the improved performance of the plug, since crosstalk is reduced by increasing the wire separation distance.

With the embodiment of the invention illustrated in the several Figures, it will be seen that after the wires engage the insert 22,64, the respective wires, in the desired sequence, converge from their respective planes to a common plane for termination. It was discovered that insertion of a unitary braid of side-by-side wires could more easily be inserted into the passageways of a connector housing than a number of discrete wires. This recognition resulted in the wire bonding technique described above.

There is an obvious advantage that can be attributed to the combination of the wire bonding procedure and the performance enhancing feature.

According to the wire bonding procedure described earlier, the wires after bonding are relatively fixed to one another. Since the wires are fixed in position at the respective ends, the wires will not resile into a common plane as would be expected with only one fixed end. Thus, the wires when bonded, such as described above, may be readily inserted into the connector as discussed above.

Claims

An electrical connector (10) of the plug assembly type for mating with a receptacle connector, where a plurality of conductors (38) are terminated therein for electrical engagement with corresponding contacts in said receptacle type connector (10), said electrical connector (10) comprising a dielectric housing (10) having a conductor receiving end (14), a conductor terminating end (18) and a passageway (20) communicating internally between said respective ends, characterized in that:
a spacing insert (22) is disposed in said passageway (20) to receive said plurality of conductors (28) and to position same in a manner to improve the crosstalk performance of the electrical connector (10), said insert (22) having an upper surface (24) and a lower surface (26) with plural grooves (34,36) arranged along said surfaces (24,26) to receive selected pairs of said conductors (38).
The electrical connector according to claim 1 wherein said insert (22) includes a tapered wall (30) facing said conductor terminating end (18), whereby said selected wires (38) of conductors along said upper surface are directed toward and between the selected pairs of conductors (38) along said lower surface (26).
The electrical connector according to one of claims 1 or 2 wherein the free ends (1-8) of said conductors (38) are arranged in a parallel manner in a common plane and bonded at said conductor terminating end.
The electrical connector according to claim 3 wherein the conductors (38) are discrete, parallel, insulated wires and a unitary ribbon cable has been formed at the end of said wires by using a wire bonding fixture for bonding the free ends of said conductors at said conductor terminating end, said fixture comprising a pair of essentially planar, dielectric members for compressively engaging said wires, heating elements arranged in parallel fashion along opposing major surfaces of said planar members, where the number of said wires is "n", and the heating elements are at least "n + 1" and that the heating elements being arranged to contact the insulation of two adjacent wires.
The electrical connector according to claim 3, wherein the conductors are discrete insulation jacketed conductors (38) aligned and bonded at the end thereof to form a ribbon type cable for ease of handling and termination wherein :

a) said plural conductors (38) have been aligned in side-by-side fashion on a first fixture (150), where said fixture includes a plurality of heating elements (48), with each heating element (48) arranged to contact the insulation jackets of an adjacent pair of said conductors (38),

b) a second fixture (50) of comparable design and function has been aligned in sandwich fashion to be opposite sides of said insulation jacketed conductors (38), and

c) electrical current has been applied to said heating elements (48) to effect a localized melting and bonding of the insulation jackets of adjacent conductors (38) to one another.
The electrical connector according to claim 5, wherein melting has changed said insulation jacketed conductors (38) from an initially circular cross-section into an irregular cross-section.