WO1996037016A1

WO1996037016A1 - Modular jack for high speed data transmission

Info

Publication number: WO1996037016A1
Application number: PCT/IB1996/000448
Authority: WO
Inventors: Dobrosav Nicolitch; Alain Dupuis
Original assignee: The Whitaker Corporation
Priority date: 1995-05-16
Filing date: 1996-05-14
Publication date: 1996-11-21
Also published as: FR2734418A1

Abstract

A modular jack (10) for high speed digital signal transmission comprises two sets of terminals (77, 75) stamped and formed from two sheets of strip metal and mounted in overlapping relationship on a connector housing member (24). The terminals comprise a mating portion (16) interconnected to an IDC connection portion (18) via a linking portion (22). Extending from the linking portion (22) are capacitor portions (20) that overlap with capacitor portions of another terminal to form capacitance coupling therebetween for eliminating cross talk between differential pairs. The integral stamped and formed capacitor portions with the mating portions and connection portions, enables production of a cost-effective modular jack for high speed data transmission such as category 5.

Description

MODULAR JACK FOR HIGH SPEED DATA TRANSMISSION

This invention relates to connectors provided with means for reducing cross-talk, to enable high speed data transmission.

There is an increase in demand for cable and connection systems to transmit digital signals at high speeds. As frequency increases, emission of "noise" increases, and this is a particular problem for closely positioned conductors which are subject to what is called cross-talk. Beyond a certain transmission frequency, cross-talk becomes unacceptably intense and thus limits the speed of data transmission. In cables, one of the ways of reducing cross-talk is by twisting pairs of conductors, where one conductor of the pair is for transmitting a positive signal, and the other conductor for transmitting a negative signal of equal intensity and timing as the positive signal. This is called a differential pair due to the nature of the opposed signals in the pair. Due to the twisting about each other, magnetic and electrical fields emitted from each of the cables cancel each other out and thus noise emitted from the pair is very low. Such pairs can thus be placed within a cable and positioned closely together whilst nevertheless transmit high speed electrical signals.

One of the problems however occurs at the connection end, where the conductors are connected to terminals within the connector. Terminals of connectors are often positioned in juxtaposed parallel relationships, and exhibit more cross-talk than between conductors of the cable. One way of reducing cross-talk effects is shown in European Patent Publication No. 583 111 where conductor pairs of a connector are crossed-over, thus behaving in a similar manner to that of a twisted cable. Crossing-over of contacts in connectors is also shown in US Patent 5,186,647. The latter shows cross-talk reduction in a modular jack, which is a standardized connector widely used in telecommunications and computer data -2-

interconnection systems. Standardized modular jacks and corresponding plugs for connection thereto, were initially designed and used for low speed data transmission systems, and are thus not necessarily the most effective connection systems for use with high speed data transmission. Due to their widespread use however, there is a need to improve the data transmission speed capabilities of modular plug and jack connectors whilst respecting the standardized interface requirements. Another means of reducing cross-talk is by judicious capacitive or inductive coupling between conductors of the connector as shown in US Patent 5,326,284. In the latter, the connector (modular jack) is positioned on a printed circuit board (PCB) having circuit traces thereon that are arranged in such a manner to couple the conductors by means of inductances and capacitances. The purpose of the coupling is to neutralize cross-talk present in the line by further coupling of the conductors to an opposite signal of equal intensity (a differential signal) . Furthermore, the capacitances and inductances can be adjusted to match the impedance of the connector with that of the cable to reduce reflection of signals. Provision of a PCB however requires an extra component and increases the cost of the connector assembly. Furthermore, the volume of the connector is also increased.

It would be desirable to have an interconnection system that is not only cost-effective, but also compact and that is for high speed data transmission, the connector thus having reduced cross-talk and controlled impedance. It would also be desirable to provide the latter aspects in a standardized modular jack connector.

It is an object of this invention to provide a compact and cost-effective connector for high speed signal transmission. It is an object of this invention to provide a standardized modular jack capable of high speed data transmission.

It is a further object of this invention to provide a compact and cost-effective means for reducing cross-talk in a connector for differential signal transmission, and that can be impedance matched with a cable connection thereto. Objects of this invention have been achieved by providing a connector comprising an insulative housing and a plurality of contacts mounted therein, the contacts having a wire connection portion and a mating portion for contact with terminals of a complementary connector, the contacts further comprising capacitor portions for capacitive coupling between contacts. In an advantageous embodiment, a first plurality of contacts are stamped and formed from a first sheet of metal, and a second plurality of contacts are stamped and formed from a second sheet of metal, the sheets being mounted in overlapping relationship whereby the contacts form a standardized modular jack, and the plate portions for capacitive coupling are in overlapping relationship. The overlapping relationship of the sheet metal allows crossing-over of the contacts for capacitive coupling between contacts that are not adjacent to each other. Also in an advantageous embodiment, connection sections of the terminals are integrally connected to the contacts and stamped from the two sheets of metal. In the latter, the connection sections are insulation displacement contacts (IDCs) and have arcuate slots for connection to insulated conducting wires inserted in cavities of a rotatable actuator that can be rotated to force the wire into the IDC slots.

A cost-effective and compact design is thus achieved due to the integral stamping and forming of contact and connection sections from two sheets of metal, whereby the capacitance sections and connection sections are substantially planar. Furthermore, capacitance plate portions can be easily trimmed to the desired overlapping length for accurate balancing of the capacitive and inductive coupling, by simple changes in the stamping dies.

Other advantageous aspects of the invention will be apparent from the claims, and the following description.

An embodiment will now be described by way of example, with reference to figures, whereby;

Figure 1 is a simplified electrical schema of a capacitive coupling arrangement that can be achieved with this invention;

Figures 2a and 2b are schematic examples of respective signals transmitted along a differential pair;

Figure 3 is an isometric exploded view of a connector according to this invention;

Figure 4 is an exploded isometric view of an internal assembly of the connector of Figure 3 showing terminals and housing parts between which the terminals are assembled; Figure 5 is an isometric view of part of the connector of Figure 3 showing a first plurality of terminals mounted to a housing base member;

Figure 6 is a view similar to that of Figure 5 but with a second plurality of terminals mounted to the housing member;

Figure 7 is a plan view of the stamped layout of a first or second plurality of terminals;

Figure 8 is an isometric view of a first member of a wire stuffer; Figure 9 is an isometric view of a second member of a wire stuffer; and

Figure 10 is a plan view of overlapping first and second pluralities of terminals to illustrate their capacitor portions. Referring first to Figure 1, eight conductors are represented by the lines numbered 1-8 of a conductor are shown. These eight conductors belong to four differential pairs A, B, C and D respectively. Signals are transmitted by the conductor pairs in a differential manner whereby one conductor of a pair carries positive voltage signals as illustrated in the Figure 2A by the signals S, and the other conductor of the pair carries a signal of equal intensity and timing, but with a negative voltage with -5-

respect to the other conductor. In a twisted pair cable, as the differential pairs are twisted about each other, emission of electromagnetic noise from each of the wires of the pair cancel each other out thus allowing high speed data transmission.

At the connector, however, the contact sections are generally positioned in a juxtaposed manner, an example of which is illustrated in Figure 1 by the contacts 1-8. Due to this juxtaposed positioning of the conductors, there is unbalanced cross-talk. As an example to explain this more clearly, consider the cross-talk between conductor 3 and the differential pair A (conductors 1,2). Conductor 3 is positioned closer to conductor 2 than to conductor 1, and therefore the noise influence of conductor 2 on conductor 3 is greater than that of conductor 1 on conductor 3. By placing a capacitance C13 between conductors 1 and 3, some of the energy of a signal being transmitted along conductor 1 is capacitively fed into conductor 3, and if the capacitance C13 is correctly dimensioned, the additional coupled signal will cancel out the noise from conductor 2 because of their opposed potential differences. The influence of the differential pair B (conductors 4,5) on conductor 3 has a similar effect, which is balanced by the capacitance C53 between conductors 3 and 5. With a similar reasoning, positioning of capacitive coupling C46 between conductors 4 and 6 and C86 between conductors 6 and 8 balances the influence of pairs B and C respectively on conductor 6. Cross-talk is thus substantially reduced between differential pairs A and D, C and D, and B and D. The differential pairs A, B and C are spaced further apart from each other, and are therefore less effected by cross-talk, in particular because the magnetic and electrical fields generated by conductors reduce in-strength proportionally to the square of the distance (generally speaking) .

Referring to Figures 3, and 6 a modular jack connector 10 is shown comprising an insulative housing 12 and a plurality of stamped and formed terminals 14 that are numbered 1-8 corresponding to the layout of Figure 1. Each of the contacts 14 has a mating portion 16, a connection portion 18 and a capacitor portion 20 connected to the mating portion via a linking portion 22 that integrally extends between the mating and connection portions.

The housing 12 comprises a first insulative housing member 24 having cavities 26 for receiving connection portions of the terminals 14, the first housing member further comprising slots 28 for receiving and guiding the mating portions 16 of the terminals. The housing 12 further comprises a second base member 30 mountable to the first housing member 24 thereby sandwiching the contacts 14 therebetween. The second housing member 30 comprises an opening 32 for receiving a modular plug therethrough for connection to the terminal mating portions 16. The second housing member 30 further comprises slots 34 for receiving free ends of the mating portions 16 for lateral guidance thereof. The first housing member 24 comprises cylindrical cavities 36 for receiving cylindrical wire stuffers 38 therein, the second housing member also comprising cylindrical cavities 40 for receiving second wire stuffers 42 therethrough.

Referring to Figures 8 and 9, the first wire stuffer 38 comprises a pair of wire receiving holes 44 that are aligned to a pair of wire receiving holes 46 of the second wire stuffer 42 when assembled theretogether. The first wire stuffer 38 has a recess 48 in its periphery that receives an extension 50 of the second wire stuffer 42 for rotatably locking the two together. The first wire stuffer further comprises a recess 52 extending from a wire receiving face 54, where the groove 52 is for receiving a tool, such as the head of a screwdriver.

Referring to Figure 3, the terminals 14 and housing members 24,30 forms an internal assembly 31 that is mounted to cover-parts 56,57 that enclose and secure the internal assembly 31 therein. The cover parts and internal assembly are securely fixable to a panel or wall mount adaptor and face plate structure 58 for mounting and providing access of the terminals 14 at the face of a wall or a panel. The face plate and mounting structure 58 can further be provided with a resiliently biasable sliding door 60 that covers an opening 62. The opening 62 provides access to the terminals for mating to a complementary modular plug connector.

Referring mainly to Figure 6, the mating portions 16 of the terminals 14 are comprised of thin strips cut from sheet metal and bent into a V-shape characteristic of conventional modular jack mating portions, where the mating portion comprises a linear section 70 extending to a free end 72, the linear section 70 being obliquely positioned in a complementary connector receiving passageway 74 and resiliently biasable against contacts of the complementary connector.

Referring to Figures 4, 7 and 10, a first set 75 of the terminals (1,5,6,7) are stamped and formed from a common strip of sheet metal 76 having the planar layout as shown in Figure 7. A second set of terminals 77 (see Figure 10) are also stamped and formed from a single strip of sheet metal with the same planar layout as that of Figure 7 but flipped-over by 180° as shown in Figure 10. The latter allows the same cutting die shape to be used for manufacturing both sets of terminals, although there is a difference in the forming of the V-shape mating portions 16 as they need to project from the plane in the same direction, rather than in opposing directions as would be the case if the terminals were produced from exactly the same die.

During the manufacturing process, the sets of terminals can be maintained attached to a lead frame 80 by cutaway portions 82 extending to the connection sections 18 for supporting the terminals 14 prior to their assembly to the first housing member 24 as shown in Figure 5, where the respective cavities 26 receive the connection portions 18 therein. Once assembled to the first housing member, the terminals can then be sheared away from the lead frame 80. The latter is enabled by provision of recesses 84 at the periphery of the first housing member 24, positioned below the cut-away portions 82 of the terminals.

Once the second set of terminals 77 has been assembled to the first housing member 24, a piece of dielectric foil 86 is positioned over the capacitor and linking portions 20, 22. The first set 75 of terminals can then be positioned thereover, whereby the mating portions 18 enter into different cavities 26 of the first housing member, but portions of the capacitor portions 20 overlap as shown in Figure 10. In the same manner as with the second set of terminals 77, the connection portions 18 are sheared away from the lead frame at the linking portions 82. The second housing member 30 can then be assembled to the first housing member 24 to securely retain and enclose the terminals 14 therebetween.

The first and second wire stuffers 38,42 are then mounted into their respective cavities 36,40 of the housing members 24,30. The extensions 50 of the second wire stuffers 42 extend through arcuate slots 90 in the connection portions 18 for engagement with the corresponding recesses 48 of the first wire stuffers 38.

The connection sections 18 of the terminals (see Figure 6) also comprise arcuate IDC slots 92 that have enlarged wire receiving portions 94 and narrow contact portions 96 for cutting through an outer insulation layer of a conducting wire for contacting the inner conducting strands thereof. There are a pair of arcuate IDC slots 92 where their enlarged portions 94 are aligned with the wire receiving holes 44,46 (see Figures 8 and 9) of the actuation members 38,42 respectively when in the disconnected position. Conducting wires can thus be inserted through the cavities 44,50 of the actuation members which is then rotated, by means of a screwdriver engaging slot 52, to force the conducting wires into the narrow portion 96 of the IDC slots for connection to the terminals. As the conducting wires are supported in holes 44,46 positioned on either side of the terminal connection portion 18, the wire can be effectively and reliably inserted into the IDC slots of the terminals.

The planar design of the connection portions 18, capacitor portions 20 and linking portions 22 enables cost-effective manufacture thereof by edge-stamping, from only two strips of sheet metal. Furthermore, a compact assembly is also provided allowing two different conducting wires to be connected to each terminal. The rotatable actuation members allow easy disconnection and reconnection of wires with a simple conventional tool such as a screwdriver.

Referring to Figure 10, the capacitor C13 between terminals 1 and 3 is formed by the overlap of capacitor portion 20 of terminal 1 with the capacitor portion 20 of terminal 3 separated therefrom by the dielectric 86 as shown in Figure 6. A free end 98 of the capacitor portion 20 of the terminal l, and a free end 100 of the capacitor portion 20 of the terminal 3 can be trimmed to the desired length for a greater or smaller overlap of the capacitor portions in order to vary the capacitance C13. The position of the free ends 98,100 can be very easily trimmed by small modifications of the stamping die such that tuning of the capacitance C13 is easily done. The latter is also important for use of the connector 10 with different applications having different data transmission speeds, which will require different capacitances for optimal functioning. To form the capacitance C53 between terminals 3 and 5, the terminal 3 is provided with a capacitor portion 20 overlapping a capacitor portion 20 of the terminal 5 which is merely a continuation of the linking portion 22 of the terminal 5. In a similar manner, capacitances C48 and C86 are provided by overlapping of capacitor portions of terminal 6 with capacitor portions of terminals 4 and 8 respectively. As can be seen in Figure 10, terminals 1,5,6 and 7 are essentially mirror- image overlaps of terminals 8,4,3 and 2 respectively.

Advantageously therefore, a modular jack for high speed data transmission is provided in a cost-effective and compact manner, due to the integral forming of capacitor portions with the mating and connection portions of the terminals. Furthermore, the capacitances can be tuned in a simple manner by trimming the length of their ends. The production of two sets of terminals with similar (but reversely overlapping) terminal sets that are easily assembled in a few steps to the housing and are compactly mounted together, provides for a cost-effective and compact assembly. An advantageous actuation means for rotational stuffing of conducting wires into the terminal arcuate IDC slots enables rapid and easy connection and disconnection to the terminals. Supporting of conducting wires by actuation members on either side of the IDC slots also ensures a reliable and effective connection therebetween.

Claims

1. A connector (10) comprising an insulative housing (12) and a plurality of juxtaposed stamped and formed terminals (14) , each having a conductor connection portion (18) and a mating portion (16) for contact with terminals of a complementary connector, characterized in that the terminals further comprise stamped and formed capacitor portions (20) extending from the mating portions (16) via linking portions (22), some of the terminals (1,5,6,7) of a first set (75) having their capacitor portions in overlapping relationship with capacitor portions of other terminals (2,3,4,8) of a second set (77) for capacitive coupling therebetween.

2. The connector (10) of claim 1 characterized in that the connector has a standardised modular jack interface for mating with a modular plug.

3. The connector of claims 1 or 2 characterized in that the capacitor portions (20) are integrally formed with the mating portions (16) .

4. The connector of any preceding claim characterized in that the first set (75) of terminals, and the second set

(77) of terminals are each formed from a single strip of sheet metal.

5. The connector of claim 4 characterized in that the terminals comprise cut-away portions (82) for linking the terminals of the sets (75,77) to respective lead frames (80) prior to assembly to a first housing member (24) .

6. The connector of claim 5 characterized in that the insulative housing (12) comprises a first insulative housing member (24) having cavities (26) for receiving the terminals (14) therein for positioning and support thereof, the first housing member comprising peripheral recesses (84) for positioning of the cut-away portions (82) therethrough such that they can be sheared during the manufacturing process.

7. The connector of any preceding claim characterized in that the capacitor portions (20) of the first and second sets (75,77) of terminals are substantially planar and parallel to each other, the first and second sets (75,77) being mounted in close relationship one on top of the other.

8. The connector of claim 7 characterized in that a dielectric foil (86) is positioned between the capacitor portions (20) of the first and second sets (75,77) .

9. The connector of any preceding claim characterized in that some of the capacitor portions (20) comprise free ends (98,100) that can be trimmed to a desired length for tuning the capacitance between overlapping capacitor portions.

10. The connector of any preceding claim characterized in that the connection portions (18) are substantially planar and comprise arcuate insulation displacement contact (IDC) slots (94,92) for rotational stuffing of conducting wires therein.

11. The connector of claim 10 characterized in that the housing (12) comprises first and second wire stuffers (38,42) rotatably mountable in housing members (24,30) on either side of the IDC slots (94,92) for stuffing conducting wires in the IDC slots, the first and second wire stuffers (38,42) comprising interengaging recesses (48) and extensions (50) for rotational locking together thereof.

12. The connector of any preceding claim characterized in that the capacitor and connection portions (20,18) of the first and second sets (75,77) of terminals are substantially mirror-image layouts of each other.