Flat cable connector with grounding clip

An electrical connector for terminating shielded flat multi-conductor cable. The connector includes a housing having a metal connector shell. A conductive spring clip is provided which contacts the metallic shielding of the cable and the metal shell of the connector housing. The conductive spring clip provides shielding for the cable at its terminated end.

FIELD OF THE INVENTION 
The present invention relates generally to an electrical cable connector 
providing a direct conductive path between the shield of an electrical 
cable and the shell of the connector and more particularly to a shield 
link between the cable and the connector which reduces electromagnetic and 
radio frequency interferences. 
BACKGROUND OF THE INVENTION 
In the electronic interconnection field, it is well-known that signal 
transmission through electrical cable may be adversely affected by 
electromagnetic and radio frequency interferences (EMI and RFI). 
Electrical cable, especially that formed in a flat array, known as ribbon 
cable, typically includes a metallic shield over the length thereof which 
provides a conductive path to drain such external interferences, thus 
reducing its adverse impact on signal transmission. While effectively 
providing a shield from EMI and RFI along the cable length, upon 
termination of the cable with an appropriate electrical connector, the 
shield is striped back at one end to expose the conductors for 
termination. Thus at the interconnections, the cable may not be adequately 
shielded. 
Techniques are known which provide shielding of the cable and the connector 
at the points of interconnection. These techniques include surrounding the 
electrical connector with a metal housing, commonly referred to as a 
back-shell, and connecting the housing to the shield of the cable. Thus, 
the back shell will be at the same electrical potential as the cable 
shield. Since the back shell surrounds the connector, the point of 
interconnection will be shielded by the back shell. Often, the front face 
of the connector itself is housed in a metal shell which is used as ground 
for the contacts which extend therethrough. Thus it becomes desirous to 
connect the metal shell of the connector to the metal back shell to assure 
complete shielding. 
In order to assure complete continuity between the shield of the cable and 
the shell of the connector, each contact point must be reliably 
maintained. Shielded connectors known presently in the art, provide a 
metallic spring clip which is inserted between the cable shield and the 
back shell. The spring clip maintains electrical contact between the 
shield and the back shell. A second similar spring clip is also used 
between the back shell and the shell of the connector. 
As can be seen, this type of interconnection requires additional multiple 
ground connection interfaces, parts not normally required for transmission 
of electrical signals. Further, the parts should be designed to close 
tolerances to assure proper functioning. The back shell, being part of the 
conductive shielding part, would be constructed of highly conductive 
metal. It is apparent that shielding consideration significantly increases 
the cost of cable interconnection. The use of less costly materials, such 
as plastic or low-conductivity metal for back shells can not be 
implemented without compromising on shielding capabilities. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide shielding from 
electromagnetic and radio frequency interferences for a signal cable 
connector. 
It is a further object to provide a conductive element in an electrical 
cable connector which provides electrical continuity between the shield of 
a signal cable and the conductive shell of the connector. 
The present invention contemplates providing a conductive element which 
spans the connector housing and provides for electrical continuity between 
the cable shield and the shell of the connector. The conductive element 
serves as an EMI and RFI drain from the cable shield and the backshell. 
In a preferred embodiment of the present invention, an electrical connector 
for flat signal cable is shown. The connector includes an insulative 
housing for supporting the cable and a plurality of contacts for 
electrical engagement with the cable conductors. The housing is supported 
in a conductive shell. A conductive element is further provided which has 
a first extent for engagement with the cable shield and a second extent in 
engagement with the conductive shell of the connector. Thus, an electrical 
path is established between the shield of the cable and the shell of the 
connector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A length of cable assembly 10 is shown in FIG. 1 which comprises plural 
transversely spaced electrical conductors 12 which are aligned in a flat 
array and surrounded in an insulative casing 13 to form a flat cable 14. 
As illustrated herein the cable 14 is a 50-conductor cable, however cables 
having other numbers of conductors may also be employed. An outer 
insulative jacket 16, typically formed of flexible vinyl or other suitable 
plastic surrounds the flat cable 14. Positioned between jacket 16 and flat 
cable 14 on each side thereof is a metallic shield 18. Shield 18 is formed 
of a layer of thinly formed metal such as aluminum and extends on either 
side of flat cable 14 along the length of cable assembly 10. In FIG. 1 for 
illustrative purposes, metallic shield 18 is shown extending beyond a 
trimmed transverse edge 19 of cable jacket 16, however in practice as will 
be described in detail hereinbelow, each metal shield 18 is trimmed along 
edge 19. 
Referring now to FIG. 2, cable assembly 10 is shown terminated in an 
electrical connector 20. Electrical connector 20 is a conventional flat 
cable connector having an insulative housing 22 which supports therein a 
plurality of electrical contacts 24 for connection to the conductors 12 of 
flat cable 14. Connector 20 may be of the type shown and described in U.S. 
Pat. No. 4,437,723 issued Mar. 20, 1984, and assigned to the assignee of 
the present invention. Connector 20 shown by way of the preferred 
embodiment is of the `D` connector variety having a front connection face 
26, which surrounds the extending portions of contacts 24. The extending 
contacts 24 are arranged in 3 successive rows of 17, 16 and 17 contacts 
each. Surrounding the front face 26 of connector 20 is a metal connector 
shell 28 formed in a `D` configuration. Connector shell 28 facilitates 
interconnection of connector 20 and provides shield continuity from cable 
assembly 10 as will be described in detail hereinafter. The metal 
connector shell 28 is also used for ground connection as a drain for RFI 
or EMI. Thus, when connected to the shield 18 of cable assembly 10, cable 
noise or other interference will be drained to ground. The termination of 
flat cable 14 to connector 20 may be accomplished in a manner which is 
conventional in the art. A strain relief device 29, also known in the art, 
secures the flat cable 14 to connector 20. 
As set forth hereinabove, it is desirous to maintain electrical continuity 
between the metallic shield 18 (FIG. 1) of cable assembly 10 and the metal 
connector shell 28. A pair of conductive spring clips 30 are provided 
which are disposed to surround the stripped extent of flat cable 14 and 
provide electrical continuity between shreld 18 and connector shell 28. 
Shown in detail in FIG. 3, spring clip 30 is substantially a flat, formed 
metallic member preferably made of copper alloy or other highly conductive 
material. Clip 30 has a first end portion 32 which includes a plurality of 
parallel extending fingers 34, which upon assembly bear against and 
contact opposed lateral surfaces 27 (FIG. 2) of metal connector shell 28. 
Plural fingers 34 are provided so that plural separate parallel paths of 
electrical contact can be established between the clip 30 and metal 
connector shell 28 (FIG. 2). Plural parallel electrical paths are desired 
as the resulting impedance will be significantly less than would be with a 
single path of contact. 
The spring clip 30 includes a bent and formed central portion 36 which is 
adapted to accommodate connector 20 in assembled condition as shown in 
FIG. 4. The opposite end 38 of clip 30 includes a shield engaging end 
portion 39. The end portion 39 is inserted into the cable jacket 16 (not 
shown) between the jacket 16 and shield 18 making intimate electrical and 
mechanical contact with shield 18. The end portion 39 is progressively 
inserted into jacket 16 with upturned protrusions 40, serving as stop 
surfaces to engage the end 19 of jacket 16 to prevent further insertion. 
End portion 39 also includes a pair of oppositely directed lances 41 which 
are struck up from a central location of end portion 39. Lances 41, which 
are transversely aligned with protrusions 40, provide for electrical 
engagement with the metal back shell as will be described in greater 
detail hereinbelow. 
Referring again to FIG. 2, a back shell 50 is shown. Back shell 50 is an 
outer housing which encloses and supports connector 20 and the terminated 
extent of cable assembly 10. In the present embodiment back shell 50 is a 
metallic member comprising a pair of mating halves 50a and 50b. Each half 
has a front face 52 (FIG. 4) which provides access to the front face 26 of 
connector 20. Upon assembly, the back shell 50 supports and secures the 
fingers 34 of spring clip 30 in intimate contact against metal connector 
shell 28, establishing electrical contact therebetween. A rear portion 54 
of each half 50a and 50b confines therebetween the extending portion 39 of 
cable assembly 10 and secures end 38 of spring clip 30 in contact with 
shield 18. The mating halves 50a and 50b may be suitably secured as is 
conventional in the art, for example by the use of self-tapping screws 59 
placed on either side thereof. 
In the present illustrative embodiment back shell 50 is formed of a 
conductive metal. When fully assembled (FIG. 4) the lances 41 of spring 
clip 30 (FIG. 3) will contact the undersurface of each half 50a and 50b. 
Electrical continuity will be established between the spring clip 30 and 
metal back shell 50. As the front face 52 of back shell 50 (FIG. 4) is in 
intimate contact with the metal connector shell 28 of connector 20, 
electrical contact will also be established therebetween. Thus an 
electrical shielding path will be provided between the shield 18 of cable 
assembly 10 and the metal shell 28 of connector 20 through metal back 
shell 50. However, the present invention provides a direct path from the 
shield 18 to the metal connector shell 28 without need to place the back 
shell 50 in the conductive path. As above described, the spring clip 30 
provides such direct electrical connection between shield 18 and metal 
shell 28. Thus, shielding for EMI and RFI may still be maintained where 
the back shell is formed of a non-conductive material such as plastic. 
Various other modifications to the foregoing disclosed embodiment will be 
evident to those skilled in the art. Thus, the particularly described 
preferred embodiment is intended to be illustrative and not limited 
thereto. The true scope of the invention is set forth in the following 
claims.