GB2344470A - reduced crosstalk modular jack socket - Google Patents

Abstract

A modular jack socket (10) for high speed signal transmission has an insulative housing (12) and a plurality of terminals (44)which may be stitched or overmoulded to a base wall (16) of the housing. The terminals (14) have PCB connection portions (36) arranged in two separated rows, the terminals being positioned in a single row substantially only at their contact portions (38).The PCB connection portions (36) are closer to the mating face of the socket than the contact points of the contact portions (38). The contact portions of the terminals are bent rearwardly from the PCB connection portions (36) towards a housing rear face (22) such that the overall length of the contacts is reduced. The short contact length and separation into two rows reduces crosstalk while enabling provision of a simple, compact and cost-effective connector. Apertures (50) in the housing (fig.10 not shown) may allow access to tools for bending the contacts.

Description

REDUCED CROSSTALK MODULAR JACK This invention relates to a modular jack connector for high speed signal communication.

Modular jack connectors, also known as RJ 45 connectors, are widely used in the communications industry for plugging data communication equipment to a network (for example telephone, facsimile, computing g equipment and the like). In order to support the high signal transfer rate of data communication equipment, it is known to provide means for reducing or balancing crosstalk between terminals of the modular jack. For example it is known to cross over conductors of signal pairs in the modular jack, as shown in US 5,186,647, or to provide the connector on a PCB with crosstalk cancellation circuits, as shown in US 5,299,956, or to provide lateral extensions in the contacts for capacitive coupling between selected terminals as shown in US 5,547,405. The implementation of these means however increases the manufacturing cost of such connectors.

It would be desirable to provide a modular jack connector that is particularly cost-effective to produce yet reduces crosstalk to enable the reliable transfer of high speed electrical It would be further advantageous to provide such connector in a particularly compact form for mounting directly on a printed circuit board.

Objects of this invention have been achieved by providing the modular jack connector according to claim 1. Disclosed herein is a modular jack receptacle connector for receiving a modular plug, the connector comprising an insulative housing and a plurality of terminals each having printed circuit board (PCB) connection portions for connection to a PCB and contact portions for biasing against complementary contacts of the modular plug, the insulative housing having a base wall, side walls, and a top wall spaced from and opposed to the base wall thereby forming a cavity portion for receiving the mating plug therein through a mating face of the connector, the top wall comprising latching shoulders for latching of the modular plug thereto, wherein the terminals extend through the base wall from an inner side bounding the cavity portion to an outer side mountable against the PCB and are bent rearwardly such that the PCB connection portions are closer to the connector mating face than the contact portions, and wherein some of the PCB connection portions are arranged closer to the mating face than others. The arrangement of the PCB connection portions in different rows increases the separation between terminals of different signal pairs, whereby the terminals are positioned closer together substantially only at their contact portions to reduce crosstalk. The overall length of each terminal is reduced to a minimum by positioning the PCB connection portions closer to the connector mating face and rearwardly bending the contact portions therefrom.

The length of the signal path and associated crosstalk \ effect is thus reduced. In addition, such., construction is particularly cost-effective to produce. Furthermore, such construction is also very compact as the terminals may be supported by the base wall only, the remaining walls serving to provide the guide and retention functions for the mating modular plug.

The PCB connection portion of the terminals may be in the form of pin terminals for reception in complementary holes of the PCB, the pin connection sections extending substantially in linear alignment with a portion of an intermediate section extending through the base wall. Each terminal intermediate section comprises a bent portion extending from a straight portion arranged in the connector base wall.

Very short terminals are thus provided and in addition only the contact portions proximate free ends of the terminals are arranged substantially or approximately in a row for contacting the complementary terminals of the modular plug. In view of the short contact portions arranged relatively close together, crosstalk is significantly reduced. The terminals may be stamped and formed from sheet metal and overmoulded by the housing.

Alternatively, the contacts may be stitched into the housing and bent within the cavity portion. The top wall may comprise an opening, the opening receiving part of the modular plug latch and enabling provision of a compact housing that is simple to manufacture, for example by injection moulding.

Embodiments of this invention will now be described by way of example with reference to the accompanying drawings, in which; Figure 1 is a perspective view of modular jack according to this invention; Figure 2 is a plan view towards a mating face of the connector; Figure 3 is a cross-sectional view through lines 33 of figure 2; Figure 4 is a view in the direction of arrow 4 of figure 2; Figure 5 is a simplified schema of an alternative foot print of the PCB connection portions of the connector; Figure 6 is a simplified schema of the arrangement of signal lines of a connector according to this invention, with additional crosstalk balancing means; Figure 7 is a perspective view of another embodiment of this invention; Figure 8 is a plan view towards the mating face of the connector of figure 7 ; Figure 9 is a cross-sectional view through line 9-9 of figure 8 ; Figure 10 is a plan view towards the mounting face of the connector of figure 7.

Referring to the figures, a modular jack connector 10 comprises a housing 12 and a plurality of terminals 14. The housing 12 is injection moulded from a plastic material, and the terminals 14 are stamped and formed from sheet metal, although they could also be formed from a strip of wire.

The housing 12 has a base wall 16, opposed side walls 18, and a top wall 20 opposed to the base wall 16.

The base, side and top walls define a plug receiving cavity 24 extending into the husing from a mating face 26 to a rear face 22 that extend in planes generally orthogonal to the base and side walls. A complementary modular plug is recevable in the cavity 24 in a plugging direction (P) for connection to the terminals 14.

An opening 28 is provided in the top wall 20 and defines (at least partially) latching shoulders 30 for engaging complementary latching shoulders of a locking member of the modular plug in order to retain the modular plug in the fully coupled position. The opening 28 receives therethrough a portion of the resilient locking member of the modular plug. The opening 28 not only renders the connector particularly compact, but also facilitates the moulding of the latching shoulders 30.

The housing base wall 16 has an outer face 34 for mounting against a printed circuit board (PCB), the housing further comprising board lock studs 37 projecting from and below the outer face 34 of the base wall 16 for assisting in locating and securing the connector to the PCB. In the embodiment of figure 1-4, the housing rear face 22 is open, similar to the mating face 26, for a compact arrangement with low material usage, and small retention shoulders 23 are provided for limiting insertion of the modular plug in the plug receiving cavity 24. A rear wall 25 closing or partially closing the rear face may also be provided, as shown in figures 7-10 In this embodiment, there are eight terminals 14 which have been numbered 1-8, as shown in figure 5 or figure 6. The eight terminals correspond to four signal pairs which are defined as the pairs: 1 and 2; 4 and 5; 7 and 8; and 3 and 6.

If the signal lines are arranged in a juxtaposed \ arrangement in a single row, crosstalk unbalance occurs because, for example, the signal line 4 is closer to the signal line 3 of the pair 3,6, than it is to the signal line 6. The same applies to signal line 5 vis à vis the pair 3,6. Unbalance also occurs between pair 1,2 and the pair 3,6. Similarly, unbalance occurs between the pair 3,6 and 7,8.

As shown in figures 4,6 and 10, by separating conductors 1-8 into two rows such that even signal lines 2,4,6,8 are in a first row and odd signal lines 1, 3,5,7 are in a second row, the electromagnetic coupling between signal lines 3 and 4 is reduced and between lines 3 and 5 is increased. As shown in figures 4 and 10, the coupling between lines 3 and 5 may, in fact, be larger than the coupling between lines 3 and 4 as the distance between signal lines 3 and 5 is less than the distance between signal lines 3 and 4. The latter has some compensating effect for crosstalk occurring in the connector and/or plug where the signal lines 3 and 4 are closer than the signal lines 3 and 5. By symmetry, the same applies with respect to the other signal line 6 of the pair 3,6 with respect to the pair 4,5.

Separation of the signal lines into two (or more) rows also reduces the effects of crosstalk between the signal pairs 1,2 and 3,6 or 4,5 and also between the signal pairs 7, 8 and 3,6 or 4,5.

In order to reduce crosstalk, other arrangements could be contemplated, for example, as shown in figure 5 where the signal pair 3,6 is positioned in a second row and the remaining signal lines are in a first row, the signal pair 3,6 thus being spaced from the remaining pairs to reduce crosstalk therebetween.

The terminals 14 each comprise connection portions 36 for connection to a PCB, and contact portions 38 for resiliently biasing against complementary terminals of the modular plug. The contact portions 38 are provided proximate free ends 40 of the terminals directed towards the rear face 22 of the housing. The contact portions 38 are interconnected to the mounting portions 36 via intermediate portions 42 that comprise a rearwardly bent or angled section 44 and a substantially straight section 46. The intermediate portions 42 are secured to the housing by extension through the base wall 16, whereby the terminals 14 may either be stitched into through cavities of the base wall 16 or, alternatively, be overmoulded by the housing. The straight section 46 of the intermediate portion 42 is secure within the housing base wall 16, and the bent section 44 is positioned within the plug receiving cavity 24, as shown in figure 1, or at the base wall inner face 33, as shown in figures 7 and 9.

The terminals 14 may thus be initially assembled or overmoulded as substantially straight pieces to the connector housing and subsequently bent into their final free standing positions shown in figures 1 and 3, by a tool entering the plug receiving cavity 24 from the mating face 26. Alternatively, the terminals 14 may be first bent and then overmoulded by the housing.

The contact portions 38 are in a juxtaposed arrangement forming a single row for contacting the juxtaposed single row arrangement of contacts of a standard modular plug. It is conceivable to arrange adjacent contact portions 38 in a slightly staggered arrangement, or extending at slightly different angles with respect to adjacent contacts, as shown in figures 7 and 9, although once the modular plug is made to the connector, the contact portions will assume roughly similar positions. The arrangement of the contact portions 38 generates some unbalanced crosstalk, particularly at high signal transmission speeds (100 MHz). The length along which signal lines extend close to each other is limited to the contact portions proximate the ends 40, thereby reducing crosstalk.

Crosstalk is further reduced by providing the terminals as short as practically possible. This is achieved by arrangement of the terminal free ends 40 towards the rear face 22 and connection portion 36 towards the mating face 26, in conjunction with separating the PCB connection portions 36 into at least two rows with respect to the mating face 26. The contact portions in the embodiments of figures 1-4 and 6 thus extend close to each other (or converge together) substantially only at their contact portions, whereby the remainder of the terminals separate apart or diverge.

If the arrangement of figure 5 is adopted, signal lines of the terminal pairs 1,2 and 4,5 and 7,8 respectively extend parallel or substantially parallel for their whole length, whereas the signal lines 3,6 have connection portions that are separated such that substantially only the contact portions of contact 3 and 6 are positioned in close spacing to the row of other contact portions.

In the embodiment of figures 1-4, and as best seen in figure 4, the close positioning of signal lines 3, 5 and 4,6, relative to the positioning between 3, 4 and 5,6, even provides some compensatory crosstalk to balance the crosstalk occurring at the contact portions.

The provision of contact portions 38 bent rearwardly from substantially straight connection portions 36 and straight intermediate section 46 enables the contacts to be as short as possible, which reduces the signal path and consequently the crosstalk between signal lines. The latter arrangement also enables provision of a particularly simple, cost-effective and compact modular jack. The terminal connection portions 36 are preferably pin shaped, extending straight from and aligned with the intermediate section 46 lodged within the housing base wall 16, although it is also conceivable to bend the contact portions 36 into surface mount legs for soldering on circuit traces of a PCB. It would also be conceivable to mount the connector on supports other than printed circuit boards, where for example the connection portion 36 plug into, or are welded to, or are soldered to, complementary conductors of such device. As best seen in figure 1 and 3, the terminals of a first row 48 and terminals of the second row 46 each have contact portions that are bent or that extend at an obtuse angle a with respect to the intermediate portion straight sections 46 thereof.

Adjacent intermediate portions 42 of the terminals and connection portions 36 in the embodiments of figures 1-4 or 7-10 are thus staggered such that the odd signal lines 1,3,5,7 are separated from the even signal lines 2,4,6,8 in the plugging direction (P).

If further crosstalk compensation is desired, it is possible to position capacitive elements (C) between signal lines 3 and 5 (see figure 6), and/or signal lines 4 and 6, for example by positioning capacitive elements between the connection portions 36 or intermediate portions 42 of the terminals 14. This could be simply implemented by soldering, or otherwise interconnecting, a capacitive element between the terminals corresponding to signal lines 3,5, or 4,6 below the outer face 34 of the base wall 16 or lodged within a groove or cavity within the base wall 16. Alternatively, the \ capacitive element could be integrally mQulded within the base wall. The separation of the terminals 3 and 5 from 4 and 6 in the plugging direction (P) facilitates the insertion of a capacitive element between the lines 3 and 5 and/or 4 and 6.

As indicated in figure 2, the terminal intermediate portions 42 may be provided with protrusions or barbs 50 for securely retaining the terminals to the base wall.

The embodiment of figures 7-10 is manufactured by overmoulding the terminals 14 with the insulative housing 12. In this embodiment, the rearwardly angled section 44 of the intermediate terminal section 42 is bent almost at 90 with respect to the section 46 extending through the base wall 16, the terminals subsequently overmoulded by the housing 12, and then bent upwards into the cavity 24 to such an extent that they recede at an angle in the cavity 24 as best seen in figures 7 and 9 for resiliently biasing against complementary terminals of a modular plug. Cavities 50, 52 are provided through the housing base 16 for receiving pin-shaped tools therethrough that bend the terminal contact portions 38 upwardly away from the base wall 16 after the moulding process. During the moulding process, the contact portions 38 and rearwardly angled portions 44 of the intermediate section are received in grooves 54 extending on the inner surface 33 of the base wall 16. The overmoulding of the terminals 14 with the rearwardly bent sections 44 thereof lying within the grooves 54 of the base wall 16 facilitates overmoulding thereof, in particular reducing the complexity of capturing the terminals within the die. As can be seen in the embodiment of figures 7-10, the angles a, a'of the first and second rows of terminals, are slightly different as the rearwardly angled sections 44 are bent from the mounting sections 46 extending through the base wall 16 substantially at/or approximate the inner face 33 of the grooves 54.

Claims (12)

1. A modular jack receptacle connector for receiving a modular plug, comprising an insulative housing having a cavity for receiving the modular plug through a mating face of the connector, and a top wall having latching shoulders for latching of the modular plug thereto, and a plurality of terminals having connection portions, contact portions for biasing against complementary contacts of the modular plug, and intermediate portions extending therebetween, wherein the contact intermediate portions extend through the base wall from an inner side bounding the plug receiving cavity to an outer side and are bent rearwardly such that the connection portions are closer to the connector mating face than the contact portions, and wherein some of the connection portions are arranged closer to the mating face than others.

2. The modular jack of claim 1 wherein the contact portions are provided proximate free ends of the terminals, the free ends being directed towards a rear face of the connector opposed to the mating face.

3. The modular jack oS claim 1 or 2 including eight terminals arranged substantially in a juxtaposed order of successive terminals respectively corresponding to four signal pairs.

4. The modular jack of any one of the preceding claims wherein the connection portions of the terminals are arranged in at least two rows that are spaced apart in the plugging'direction of the modular plug.

5. The modular jack of any one of the preceding claims wherein each of the terminal intermediate portions comprises a straight section lodged within the base wall and a rearwardly bent portion (44) extending therefrom and positioned within the plug receiving cavity.

6. The modular jack of any one of the preceding claims wherein the terminal contact portions extend at an obtuse angle with respect to the connection portions.

7. The modular jack of any one of the preceding claims wherein the top wall comprises a through opening defining the latching shoulders.

8. The modular jack of any one of the preceding claims wherein a rear face of the connector opposed to the mating face comprises an opening extending therethrough in the plugging direction of the modular plug of similar dimensions to the modular plug receiving opening of the mating face.

9. The modular jack of any one of the preceding claims wherein the terminal connection portion relating to a first signal line of each pair of signal lines is positioned in a first row, and one connection portion relating to a second signal line of each said pair of signal lines is arranged in at least a second row spaced from the first row in the plugging direction of the modular plug.

10. The modular jack of any one of the preceding claims wherein a capacitive element is provided between the connection portions or intermediate portions of terminals corresponding to signal lines or of different pairs of signal lines.

11. The modular jack of any one of the preceding claims 1-8 wherein the connection portion of at least one pair of signal lines is separated in the plugging direction of the modular plug from the connection portions of the remaining signal lines.

12. A modular jack receptacle connector constructed and arranged substantially as hereinbefore described with reference to Figures 1 to 6 or 7 to 10 of the accompanying drawings.