Grounding of shielded cables in a plug and receptacle electrical connector

Cable wires to be interconnected by a plug and receptacle connector are received within the end portion of each connector part, the cables themselves being conventionally connected to a pin and socket contacts. The contacts are received within insulative inserts which, in turn, are mounted within metal shell members. A portion of the cable shields outwardly of the insulative inserts are located on the outer end portion of a connector part metal shell surrounding the inserts. A metal ring is placed over the individual cable shields and formed in place mechanically securing and electrically connecting the cable shields to the metal cylinder and thus to the connector part.

The present invention relates generally to the grounding of shielded cables 
in a plug and receptacle electrical connector, and, more particularly, to 
such a cable termination means at the connector to prevent pollution from 
external radio frequency and electromagnetic energy. 
BACKGROUND OF THE DISCLOSURE 
Electrical connectors having plug and receptacle parts which can be mated 
together for interconnecting cable wires by pins and sockets are 
well-known and have been found to be a highly reliable form of 
establishing releasable electrical connections under a great variety of 
environments. The cable wires are typically enclosed by a shield such as a 
metal braid for grounding at the cable ends to prevent radio frequency and 
electromagnetic energy in the surroundings from interfering with the 
equipment to which the cables connect. Also, such shields are useful in 
preventing cross-interference with other cables. 
There has been considerable concern expressed about the possibility of 
nuclear explosions generating an electrical pulse (EMP) of such magnitude 
as to destroy communications and wipe out data bases in computers, for 
example, over a relatively large geographical area. Such a problem not 
only has severe consequences for the public generally, but also would be 
devastating on military electronics. Shielding of sensitive electronic 
circuits, components, and cables by enclosing them within a conductive 
member that would conduct such EMP energy to the ground can be effective, 
if properly handled. However, any gap that may exist in the conductive 
path to ground could result in destruction of the protective circuitry 
and, therefore, to be fully effective such grounding protection must exist 
not only on the cables themselves but also at any connector. 
SUMMARY 
The cable wires to be interconnected by a plug and receptacle connector are 
received within the end portion of each connector part, the cables 
themselves being connected to pin or socket contacts, as the case may be, 
in a conventional manner. The pin and socket contacts are received within 
insulative inserts which, in turn, are mounted within metal shell members. 
The termination means described herein contemplates removing a portion of 
the cable shields outwardly of the insulative inserts and locating the 
shield portions on the outer end portion of a connector part metal 
cylinder which surrounds the inserts. A metal ring is then placed over the 
individual cable shields that are located on the metal cylinder end 
portions and it is formed in place securing and electrically connecting 
the cable shields to the metal cylinder and thus the connector part. 
The entire set of cable wires forming the cable itself typically has a 
single flexible shield enclosing each of the individual cable wires and 
for termination by the means described herein it is peeled back even 
farther than the individual cable shields terminated as already described. 
A metal ring of such dimensions as to permit receipt between the overall 
shield and the individual cables is received within the overall shield and 
the connector backshell is received onto the connector part over the 
individual termination ring and over the overall shield termination. The 
backshell is then secured in place making full contact with the individual 
shields as well as the overall cable shield and the connector parts. 
Application of a relatively large magnetic field pulse causes the 
backshell to form about the enclosed part.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Turning now to the drawing and especially FIG. 1, one half of a plug and 
receptacle connector, namely a receptacle, with which the present 
invention can be advantageously employed is identified generally as at 10. 
The connector part is seen to include as a major part, a hollow generally 
cylindrical metal shell 11 within which pin or socket contacts may be 
located to establish connection in a known manner upon mating of the 
connector parts. That is, another connector part (plug) releasably fits 
with the receptacle 10 to connect paired sets of cable wires. The shell 11 
and an integrally related mounting plate 12 are typically constructed of a 
high-quality aluminum plated with a suitable metal or alloy to prevent 
oxidation or corrosion. 
Referring now also to FIG. 3, the cylindrical shell 11 has, on the side of 
the mounting plate 12 at which the cable wires are to be inserted into the 
connector, one or more flanges 13 and 14 extending outwardly of the shell 
and circumferentially about the shell and which, in a way that will be 
described, serve as an anchoring and connection means to the cylindrical 
metal backshell 15. 
The cable identified generally as at 16 includes a plurality of cable wires 
17 each one of which includes its own shield 18. Typically, the cable wire 
shields are braided wire which not only is conductive so as to serve as an 
electromagnetic energy shield, but also is sufficiently flexible to permit 
desired bending of cable 16. Moreover, over the entire set of cable wires 
17 with their individual shields, there is a further conductive shield 19. 
Preliminary to terminating the various cable shields, the overall cable 
shield 19 is peeled back onto the cable itself a substantial distance from 
the end of the cable wires (FIGS. 1 and 3). Also, at this time an annular 
metal termination ring 20 is slid onto the end of the cable and located 
over the shield 19 and underneath the peeled back portion thereof. 
Next, the outer end portion of each of the individual cable wire shields 18 
are stripped off a given length from the ends of the cable wires and 
formed to extend angularly outwardly from the cables as individual 
conductors (FIG. 3). Each of these stripped-off cable shields 18 are 
received over and onto an outer end portion of the connector part shell 
11. An appropriately dimensioned metal ring 21 is received over the ends 
of the stripped-off cable shields 18 and onto the end portion of the shell 
11. The ring 21 is then deformed radially inwardly onto the shell 11 
thereby physically and electrically securing the cable shields to the 
shell 11. Preferably, the ring 21 is formed about the cable shields 
through the application of a relatively large magnetic field which not 
only presses the ring material tightly against the shields, but also 
deforms the ring downwardly between adjacent cable shields into contact 
with the receptacle shell as at 22 (FIGS. 1 and 2). 
An elongated metal cylinder or backshell 15 is then received onto the cable 
and located over flanges 13 and 14 as well as adjacent parts of the cable 
and termination means already described (FIG. 1). Finally, further 
deformation such as by a magnetic field secures the backshell 15 to the 
flanges 13 and 14 as well as establishing mechanical and electrical 
contact with the overall cable shield 19. 
The cable wires forming the cable has a single flexible shield enclosing 
all of the wires which is peeled back farther than the individual cable 
shields terminated as already described. A further metal ring is received 
within the overall shield and the connector backshell is received onto the 
connector part over the individual termination ring and over the overall 
shield termination. The backshell is then secured in place making full 
contact with the individual shields as well as the overall cable shield 
and the connector parts. 
In use of the described shielding means both the overall shield 19 for a 
multi-wire cable and the individual cable wire shields 18 are mechanically 
and electrically connected to the connector part shell (e.g., receptacle). 
Interference signals induced in the outermost shield 19 are interconnected 
to the connector part 10 via the backshell 15 and then grounded through 
the mounting plate 12. Any interference signals that may have been picked 
up by the individual shields 18 are directly fed to the connector part 
shell 11 closely adjacent the point where the shields leave the cable 
wires and then to ground. The backshell completely encloses the cable wire 
end of the connector part thereby preventing interference signals being 
induced in the cable wire and portions from which the shield 18 has been 
stripped.