Shielded electrical connectors

An RF screened plug-in connector comprises a plug (14, FIG. 2A) and a socket connector device (44) that includes a socket (15) and a circuit board (16). The plug is on the end of a screened cable (3), the screen of which is internally connected to a conductive surface (9) of the plug. The socket has a body (18) which is open to provide access to conductive tracks (17) on the circuit board (16). The body has an internal conductive surface portion (21a) which is pressed into intimate contact with a conductive surface portion (9a) on the plug, by virtue of the reaction between resilient contact fingers (12) on the plug pressing on the tracks (17) on the board. The socket body (18) is held in contact with the board (16) by latches (20, FIG. 2C) which also have conductive surfaces and which contact a conductive layer (42) on the underside of the board.

BACKGROUND OF THE INVENTION 
This invention relates to shielded electrical connectors. 
Shielding, or screening, to reduce RF interference is an increasing 
requirement in data equipment. Shielding of connectors is most commonly 
provided by means of inter-fitting metal casings as exemplified by 
EP0112713. EP0112648 shows an alternative design of a shielded connector 
in which a one-piece metallic casing is provided with two hinge portions 
so that it can be hinged to form an enclosure surrounding the conductors 
contained within the electrical connector. A disadvantage of these 
shielded connectors is that any imperfections in the fitting together of 
the metallic casings could create slot antennae, which may actually emit 
interference. 
An attempt to circumvent this problem is disclosed in EP0090539, in which a 
two-part casing is provided with a stepped peripheral flange. The flange 
produces a more closely inter-fitting casing with less tendency to produce 
slot antennae. The casing is formed of an insulating material, plated with 
conductive material on the inside surfaces thereof. 
The present invention seeks to provide an improved shielded electrical 
connector having none of the disadvantages associated with inter-fitting 
shielding casings. 
SUMMARY OF THE INVENTION 
In accordance with one embodiment of the present invention, a connector 
system with two mating connector devices is provided, which effectively 
connects shieldings of the connector devices. One of the connector devices 
has resilient contacts for engaging contacts on the other connector 
device. The force of the resilient contacts presses conductive surfaces of 
the two devices into intimate engagement. The connector devices may be 
connectors or circuit boards with multiple contacts. 
The novel features of the invention are set forth with particularity in the 
appended claims. The invention will be best understood from the following 
description when read in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a shielded plug connector device or plug 14 that includes a 
housing 1 having an opening 2 that receives an inserted end of a cable 3. 
The cable includes at least one wire 6, an insulating sheath 5 around the 
wires, and a metallic braided screen 4 around the sheath. Prior to 
insertion of the cable end, the screen and sheath are cut back to expose 
the wires 6. The sheath 5 is cut back further than the screen 4 to allow 
the screen to be folded back over the end of the sheath as shown at 7. 
The plug housing 1 includes a resilient integral strain-relieving part 8 
that presses against the inserted cable to retain it in the plug housing. 
The left hand portion of the housing 1 has a continuous 
electrically-conductive coating 9 which may be applied by a plating 
process on a plastic housing portion. This conductive surface 9, which 
covers the inside of the strain relieving part 8, provides an 
electrically-conductive path between the folded-over end 7 of the screen 
and the exterior of the plug housing 1. 
The extreme ends of the cable wires 6 enter a blind bore in the right hand 
portion of the plug housing where each wire is engaged by tangs 10 of an 
insulation-piercing contact that pierces insulation of the wire to contact 
a conductor in the wire. Each contact 11 includes a resilient contact 
finger 12 that is integral with the tangs 10 and which normally projects 
from the outer surface of the plug. 
The right hand portion of the plug housing 1 is left unplated (except 
possibly at its extreme end) in order to prevent short-circuiting of the 
contact 11 The housing includes a separate insert 13 of insulating 
material in which the contact 11 is mounted. 
FIGS. 2A, 2B and 2C show the first component or plug 14 cooperating with a 
second component or connector device 44 which includes a socket 15 and a 
printed circuit board 16, which are all part of a connector system 46 that 
includes the plug. The socket 15 is shown in side sectional views in FIGS. 
2A and 2B and in an end sectional view in FIG. 2C. In FIG. 2A, the plug is 
shown at the start of insertion in the socket, and in FIG. 2B the plug is 
shown fully inserted. 
The socket 15 is adapted to be mounted on a printed circuit board. 16 
provided with contacts in the form of conductive traces 17. As is most 
evident from FIG. 2C, the socket comprises an insulative housing or body 
18 of substantially U-shaped section (the right side of the enclosure of 
FIGS. 2A and 2B can be closed). The socket can be attached to the board by 
inserting vertical sides of the socket body through corresponding slots 19 
in the board. Latches 20 of the lower ends of the socket body sides retain 
the socket in its fully inserted position relative to the board. The 
socket and circuit board together form an enclosure 48 for receiving the 
plug. (The right side of the enclosure of FIGS. 2A and 2B can be closed). 
The socket body 18 is open at the bottom. Traces 17 on the board are 
exposed so that when the plug 14 is inserted as shown in FIGS. 2A and 2B, 
contact fingers 12 of contacts 11 of the plug make resilient contact with 
the conductive traces 17. 
The socket body 18 is coated internally and externally e.g. by plating, to 
provide a continuous electrically-conducting surface 21 which makes direct 
contact with the conductive surface 9 on the inserted plug. This provides 
a continuous conductive path between the screen of the cable 3, the 
exterior conductive surface 9 of the plug 14, and the interior conductive 
surface 21a of the socket 15. The resilient contact fingers 12 of the plug 
press in a downward direction against the conductive traces 17 of the 
circuit board. The downward pressing of the resilient contacts 12 results 
in a reactive upward force on the plug housing 1. This results in the 
upper conductive surface portion 9a of the plug housing being pressed 
against the conductive lower internal surface portion 21a of the socket 
housing or body. Such reactive forces are created because the contacts 12 
press in only one direction against the mating traces or contacts 17. The 
conductive coating on the exterior of the body 18 is continued over the 
latches 20 which, in turn, are pressed into engagement with a screening 
conductive layer 42 on the underside of the board 16. 
In an alternative construction to that shown, the entire socket 15 may be 
made of electrically conductive material. Similarly the housing 1 of the 
plug may be made of solid conductive material (except for insert 13, whose 
front may be coated with metal). 
FIGS. 3A, 3B and 3C show a unitary shielded component or plug device 22 for 
mounting on a printed circuit board component 23, FIGS. 3A and 3B being 
diagrammatic side views and FIG. 3C an end elevation view. 
The plug or plug device 22 is an assembly that comprises a housing 24 of 
plated insulating material similar to the housing 1 of the plug in FIGS. 
1, 2A, 2B and 2C. A cable end 25 of a flat cable, is received in the plug 
assembly housing 24 and retained therein by a strain-relieving housing 
part 26 (FIG. 3A) in the same way as described in relation to FIG. 1. The 
part 26 is coated with a conductive layer contiguous with a layer on the 
exterior of the housing so that, as described above, there is a continuous 
screening path between the folded back end of the screen 27 on the cable 
and the exterior of the housing. As described above, the conductive 
coating on the exterior of the housing is interrupted in the region of 
resilient contact fingers 28. 
The plug 22 is arranged to be slid over the edge of the printed circuit 
board component or board 23 so that the contact fingers 28 can mate with 
conductive tracks 29 on the board as shown in FIGS. 3B and 3C. 
Alternatively, the arrangement can be regarded as one in which the printed 
circuit board is received in the plug. 
The plug housing 24 is provided with downwardly-extending arms 30 (FIG. 3C) 
which engage in slots 50 in the board 23. The arms 30 terminate in feet 
plug portions 31 which are pressed upwardly against the bottom of the 
board 23 by the resilient force exerted by the contact fingers 28. The 
contact fingers are mounted on another plug portion 54 of the plug 
housing. The upper surfaces of the feet portions 31 are conductively 
coated by plating or the like as shown at 32, which coating is contiguous 
with the coating on the exterior of the housing 24. The upward pressure 
exerted on the feet portions or feet 31 causes the coating 32 to be forced 
into conductive engagement with a screening layer 33 on the underside of 
the board 23. In this way a continuous conductive path is formed from the 
screen of the cable 25 through the coating on the housing 24 to the screen 
coating 33 on the printed circuit board. 
FIGS. 4A and 4B are side sectional views of a double plug and socket 
connection of the kind used in the type of variable interconnection 
referred to as "patching". 
A double socket housing 34 is made of metal or coated with a conductive 
layer to form a conductive surface 35. The housing is provided with guides 
36 to receive in parallel relationship plugs 37 and 38 inserted from 
opposite ends and in inverted relationship. FIG. 4A shows the plugs at the 
beginning of their insertion while FIG. 4B shows the plugs in their final 
or fully inserted position. 
First plug 37 is a component of the type described in FIGS. 1, 2A, 2B and 
2C. It is provided with a housing part 52 with an external conductive 
coating connected to the screen of its cable 39, the coating being 
interrupted in the vicinity of one or more resilient contact fingers 40. 
Second plug 38 is of similar design to first plug 37 except that the 
resilient contact fingers 40 are replaced by one or more fixed contacts 
41. The second plug 38 and double socket housing 34 form a second 
connector device or component that mates with the first component or plug 
37. 
When the two plugs are fully inserted as shown in FIG. 4B, the contact 
fingers 40 resiliently engage corresponding fixed contacts 41 on the other 
plug. At the same time, this resilient engagement produces a reaction 
tending to press the two plugs apart and forcing their non-contact sides 
into close contact with conductive surface portions of the housing 34. 
This not only results in the plugs being held firmly in the housing, but 
also results in the conductive or screening layers 52, 53 on the exteriors 
of the plugs making good contact with the screening layer 35 on the double 
socket housing. 
Thus, the invention provides connector systems wherein one or more contacts 
on a first connector component or device engage corresponding contacts on 
a second connector component or device, wherein good contact is made 
between RF screening material on the mating devices in a low cost and 
reliable construction. The two connector devices have housings with 
RF-shielding or screening conductive surfaces, and their mating contacts 
include a set of contacts with resilient fingers. The force of the 
resilient fingers on one connector device pressing in a first direction 
against contacts on the other device, presses a conductive surface of the 
first device in a second direction against a conductive surface of the 
other device. A cable with a screen around its wires, has its screen 
connected to a housing conductive surface by a conductive surface on a 
strain-relieving integral part of the housing. 
Although particular embodiments of the invention have been described and 
illustrated herein, it is recognized that modifications and variations may 
readily occur to those skilled in the art, and consequently, it is 
intended that the claims be interpreted to cover such modifications and 
equivalents.