CA2464834A1 - Connector - Google Patents

Description

TITLE OF THE INVENTION
CONNECTOR
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 provides an exploded view of a connector in accordance with an illustrative embodiment of the present invention;
Figure 2 provides a raised front perspective view of a support structure with flexible PCB attached in accordance with an illustrative embodiment of the present invention;
Figures 3A and 3B provide top and bottom side views of a flexible PCB in accordance with an illustrative embodiment of the present invention;
Figure 3C is a sectional view along 3C in Figure 3A;
Figure 4 provides a schematic view of a plug and compensating network in accordance with an illustrative embodiment of the present invention;
Figure 5 provides a raised front perspective view of a flexible PCB in accordance with an illustrative embodiment of the present invention;
Figure 6 provides a raised front perspective view of a support structure with a PCB attached in accordance with an alternative illustrative embodiment of the present invention;
Figure 7 provides a side perspective view {from below) of a contact assembly and compensating network in accordance with a second alternative illustrative embodiment of the present invention; and

2 Figure 8 provides a raised rear perspective view of a connector in accordance with a third illustrative embodiment of the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
Referring now to Figure 1, an illustrative embodiment of a connector, generally referred to using the reference numeral 10, will now be described.
Connectors as in 10 are typically modular and designed for snapping into a panel 12 provided with one or more cut away connector receptacles as in 14 therein, or alternatively for mounting directly on printed circuit boards or the like (not shown) as part of a larger circuit assembly. The connector 10 serves as receptacles for a cable plug which terminates a telecommunications cable (both not shown), for example those conforming to the well known and ubiquitous RJ-45 standard. The cable plug is inserted into a plug opening 16 located in a forward part 18 of the connector 10.
Illustratively, the connector 10 is comprised of a two part housing comprised of the forward part 18 and a rearward part 20 both manufactured from a suitable rigid non-conducting material such as plastic. A series of contact elements 21 comprised of contact strips 22 are disposed within the housing and enclosed therein when the forward part 18 is assembled to the rearward part 20. The series of contact strips 22 are illustratively etched on a first surface 24 of a Printed Circuit Board (PCB) 26 manufactured from a non-conductive (dielectric) and illustratively flexible material such as polymide, Kapton~, etc., and coated with a conductive material such as copper or aluminium to form a contact assembly. As known in the art, lithographic techniques can be used to selectively remove a surface layer of conductive material from a PCB leaving conductive traces supporked by a non-conductive substrate. The exposed series of contact strips 22 are typically covered in a conductive material having high oxidation potential, such as gold.
As will now be apparent to those of ordinary skill in the art, as a cable plug

3 (not shown) is inserted into the plug opening 16, each of the contacts within the cable plug will press against a complementary one of the series of contact strips 22. Given the flexible nature of the PCB 26, the series of contact strips 22 will tend to deflect away from the cable plug. In order to ensure that good contact is maintained between the contacts disposed within the plug and the series of contact strips 22, a rigid support structure 28, for example manufactured from a non-conductive material such as plastic, is provided around which the PCB 26 is wrapped. A series of non-conductive supporting blades with limited flexibility as in 30 are mounted at a first end 32 to the support structure 28, each of the blades as in 30 positioned under one of the series of contact strips 22. The blades 30 provide an independent countering force tending to bias the series of contact strips 22 towards the contacts of the cable plug and thereby ensuring a reliable contact when the cable plug is inserted into the assembly 10. Additionally, to improve the flexibility of the series of contact strips 22 relative to one another, the material between adjacent contact strips 22 is removed during fabrication of the PCB 26.
Referring now to Figure 2, each of the series of contact strips 22 is in contact with a particular Insulation Displacement Connector (IDC) terminal as in 34.
As is known in the art, when a small gauge insulated wire as in 36 is inserted between the bifurcated conductive blades 38, 40 of an IDC terminal 34, an incision is made in the insulation 42 of the wire 36 allowing the conductive blades 38, 40 to come into contact with the conductor 44 of the wire 36.
Note that, although the present illustrative embodiment discloses the use of IDC terminals, alternatively the IDC terminals could be replaced with other types of terminals, for example rigid contact pins, thereby allowing the connector 10 to be soldered directly to a PCB or the like (not shown).
Referring now to Figure 3A and Figure 3B, a contact assembly 45 will now be described. The series of contact strips 22 are interconnected with the contact pads 46 for the IDC terminals (34 in Figure 2) via a series of traces 48 etched

4 onto the first surface 24 and a second surface 50 of the PCB 26. Additionally, a compensating network 52 comprised of a series of selectively interconnected compensating elements 54 is provided for. Referring now to Figure 3C, each compensating element 54 is comprised of a first contact plate provided by the contact strip 22 etched into the first surface 24 of the PCB

and a second contact plate 56 which is etched onto the second surface 50 of the PCB 26. As will now be understood by a person of ordinary skill in the art, the combination of the dielectric material of the PCB 26 sandwiched between the contact strip 22 and the contact plate 56 provides for a capacitive compensating element 54. One great advantage of this construction is that the compensating elements as in 54 are located at the point of contact between the connector 10 and plug (not shown) which in turn greatly improves the high frequency behaviour of the compensating network 56.
As is known in the art, elements such as connectors 10, cables and plugs (both not shown) introduce parasitic reactances thereby causing unbalanced behaviour in regards to cross talk, noise immunity, etc. which adversely affect the performance of a the communications system which these elements form part of. Additionally, adjacent conductors are coupled to one another to some degree and in this manner cross-talk is introduced into the communications signals. The compensating network 52 introduces reactances which compensate for these parasitic reactances, thereby improving performance, especially at high frequencies, in terms of reduced cross talk, reduced noise, etc.. As known in the art, such compensation networks can be formed by combinations of compensating elements 54 including, for example, one or more capacitive elements.
Note that although the present illustrative embodiment describes a flexible PCB 26 having two conductive layers separated by a dielectric substrate, a person of ordinary skill in the art will understand that a multilayer PCB, wherein a plurality of conductive layers are separated by a plurality of dielectric substrates, could also be used.

In connectors, cables and plug assemblies according to the RJ-45 specifications, eight (8) conductors are arranged in pairs which are twisted together to form the twisted pairs widely used in telecommunications systems.

5 Referring now to Figure 4, an RJ-45 plug can be modelled as a series of contacts as in 58 terminating a series of conductors 60 and between which a series of parasitic capacitances as in 62 have been introduced. When the plug is inserted into the connector the series of contacts as in 58 come into contact with the contact strips as in 22 which also form the first contact plates of the capacitive compensating elements 54. As discussed hereinabove, the compensating elements 54 are arranged as a compensating network 52 which is designed in a manner to compensate for, or balance, adverse effects which would otherwise be introduced by the parasitic capacitances 62. In this regard, and still referring to Figure 4, the series of capacitive compensating elements designated 54~ are compensating for the differential parasitic capacitances 62. Additionally, a second series capacitive compensating elements (designated 542) can optionally be added to compensate for the common mode noise signal generated by the combination of the parasitic capacitances 62 and the capacitive compensating elements 54~.
Referring now to Figure 5 in addition to Figure 2, during assembly the PCB 26 is formed to fit the support structure 28. Referring to Figure 6, however, in an alternative construction of the support structure 28, a similar connector 10 can be assembled without significantly bending the PCB 26. This would allow the use, for example, of more rigid PCB constructions, for example those manufactured from thin sheets of FR4 epoxy laminate. The PCB 26 of Figure

6 also has the advantage that the interconnecting traces (not shown) between the series of contacts 22 and the iDC terminals as in 34 are somewhat shortened.
Referring to Figure 7, in a second alternative embodiment, the non-conductive supporting blades as in 30 of Figure 1 could be replaced by a series of metal tines 64. The tines 64 could be used to support the PCB 26 of Figures 3A and 3B with provision of a suitable dielectric between the tines 64 and the PCB
26.
Alternatively, the compensating elements 54 can be formed directly on the tines 64, for example using a suitable non-conductive adhesive (not shown).
In this regard, the tines 64 provide the first contact plate of the capacitive compensating elements 54, with provision of a suitable dielectric between the second contact plates 56 and the tines 64 (for example, a strip of dielectric material disposes between the surface of the tines 64 and second contact plate 56. The second contact plates 56 of the compensating elements 54 are interconnected with the first contact plates formed by the tines 64, illustratively using a series of small gauge wires as in 66, in order to form a compensating network.
Referring now to Figure 8, the use of a flexible PCB 26 also allows for variations in the manner in which the IDC terminals as in 34 are arranged without any significant modifications to the PCB 26. This allows, for example, for improved termination of the cable 68, for example by reducing the amount the individual wires 36 of the twisted pairs must be unwound prior to insertion of the wires 36 between the bifurcated conductive blades 38, 40 of the IDC
terminals 34. Improvement of the interconnection between cable 68 and connector 10 in turn provides for improved performance.
Although the present invention has been described hereinabove by way of illustrative embodiments thereof, these embodiments can be modified at will without departing from the spirit and nature of the subject invention.

Claims (8)

WHAT IS CLAIMED IS:

1. A compensating connector, the connector adapted for receiving a cable plug having a plurality of terminal contacts, the connector comprising:

a plurality of contact strips; each of said contact strips adapted to contact with one of said terminal contacts; and a compensating network comprised of a plurality of compensating elements;

wherein one of said contact strips acts as a first contact plate for each of said compensating elements.

2. The connector of claim 1, wherein said connector is adapted for mounting on a printed circuit board.

3. The connector of claim 1, wherein said connector is adapted for mounting to a cable.

4. A contact assembly for a compensating connector, the assembly comprising:

a plurality of contact strips arranged on a substrate; and at least one compensating elements;

wherein said substrate is fabricated from a dielectric material and wherein one of said contact strips acts as a first contact plate for each of said compensating elements, a second contact plate of each of said compensating elements being selectively interconnected with one of said contact strips, said compensating elements compensating for parasitic reactances.

5. The contact assembly of claim 4, wherein said dielectric material is flexible.

6. The contact assembly of claim 4, wherein said substrate is a multilayer substrate.

7. The contact assembly of claim 4, wherein said at least one compensating elements are capacitive.

8. A compensating network for use in a compensating connector, the connector adapted for receiving a cable plug, the network comprising:
a first series of compensating elements compensating for differential parasitic capacitances introduced by the cable plug; and a second series of compensating elements compensating for common mode noise signals generated by said differential parasitic capacitances and said first series of compensating elements.