U.S. patent number 3,912,354 [Application Number 05/447,768] was granted by the patent office on 1975-10-14 for ground connector for shielded cable.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to Donald S. Campbell, Edward A. Stephan.
United States Patent |
3,912,354 |
Campbell , et al. |
October 14, 1975 |
Ground connector for shielded cable
Abstract
A connector for use in making permanent electrical contact
between selected wire-conductors of a shielded flat cable and the
conductive shield comprises a series of insulationpiercing
bifurcate spring compression reserve contact elements held under
conductive spring tension in a conductive support which is retained
in conductive contact with said shield by a surrounding frame.
Inventors: |
Campbell; Donald S. (St. Paul,
MN), Stephan; Edward A. (St. Paul, MN) |
Assignee: |
Minnesota Mining and Manufacturing
Company (St. Paul, MN)
|
Family
ID: |
23777670 |
Appl.
No.: |
05/447,768 |
Filed: |
March 4, 1974 |
Current U.S.
Class: |
439/404;
439/607.01 |
Current CPC
Class: |
H01R
12/675 (20130101) |
Current International
Class: |
H01R 013/38 () |
Field of
Search: |
;339/14,17,18,19,95,97-99,143,222,DIG.3 ;174/36,88R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Attorney, Agent or Firm: Alexander, Sell, Steldt &
DeLaHunt
Claims
I claim:
1. A ground plane connector for making permanent conductive
electrical contact between the ground plane and selected
wire-conductors of a longitudinally ribbed shielded flat cable,
comprising: a contact carrier having electrically conductive
contact element supporting pockets communicating physically and
conductively with an electrically conductive surface; at least one
resilient bifurcate electrically conductive flat plate contact
element fitting within and making conductive contact with a said
contact element supporting pocket and extending from the contact
element supporting pocket beyond said conductive surface in
position for making connection with a corresponding
wire-conductor,; a cover fitting over said electrically conductive
surface of said carrier, grooved to receive the said contact
elements and having transverse ridges extending from adjacent the
grooves for assuring alignment of said ribbed cable; and means for
aligning said cover on said contact carrier and for maintaining the
two in forceful contact with a cable section placed
therebetween.
2. Connector of claim 1 wherein said contact carrier is an assembly
of two substantially identical plastic bodies with adjacent faces
channeled to provide said element-supporting pockets and with all
surfaces having a conductive metal surface coating.
3. Connector of claim 2 wherein said contact elements include a
generally J-shaped stem fitting within said element-supporting
pocket and making spring contact with said metal coating.
4. Connector of claim 1 including a recessed body member for
supporting said contact carrier and having serrated outer end
surfaces, and wherein said cover is provided with depending ends
having cooperatively serrated inner surfaces.
Description
This invention relates to electrical connectors and has particular
reference to connectors useful in providing contact between the
shield and one or more of the wire-conductors of a multi-conductor
shielded flat cable.
Flat cables are much used in the wiring of printed circuit and
other complicated electrical and electronic systems. Such cables
may contain a large number, upwards of fifty or more, small
wire-conductors of circular cross-section per inch of width. In
order to minimize cross-talk and other forms of interference, it is
found advantageous to include in the cable structure a conductive
shielding layer and to ground selected wires thereto. In some
instances one wire of each pair of wires may be thus connected.
Connection by stripping and soldering has been practiced but is a
delicate and time-consuming operation.
The present invention provides a connector with which any desired
number of the wire-conductors of a shielded flat cable may be
effectively and permanently connected with the shield in a single
simple operation involving only the exposing of the shield and the
pressure assembly of a three-part connector about the exposed
section. Removal of the outer insulating layer covering the shield
is easily accomplished by careful hand cutting and stripping, or
more conveniently by controlled mechanical abrasion. Assembly of
the connector involves merely positioning the three parts against
the surfaces of the cable and then forcing them together with a
suitable hand- or power-operated press. Low resistance contact
between wires and shield is obtained immediately and is thereafter
maintained under all normal conditions of use.
In the drawing,
FIG. 1 is a view in perspective showing a connector of the
invention mounted on a section of shielded flat cable,
FIG. 2 is a partial view in cross-section and on an enlarged scale
taken approximately at line 2--2 of FIG. 1,
FIG. 3 is a top plan view, and FIG. 4 a section taken approximately
at line 4--4 thereof, of the body member of the connector,
FIG. 5 is a bottom plan view, and FIG. 6 a section taken
approximately at line 6--6 thereof, of the cover member,
FIG. 7 is a top plan view, FIG. 8 a section taken approximately at
line 8--8 thereof, and FIG. 9 a similar section with a contact
element inserted, of the assembled contact carrier member, and
FIG. 10 is an elevation taken approximately at line 10--10 of FIG.
7 showing an inner face of one segment of the two-part contact
carrier member.
The connector 11 of FIGS. 1 and 2, shown applied to a cable 12, is
composed of three major components, namely a recessed body 30, a
ribbed and grooved cover 50, and a contact carrier 70 containing
one or more bifurcate contact elements 90.
The cable 12 contains a plurality of parallel small wires 13 within
a strip of insulating material 14 which is ridged at the upper
surface above each wire, forming ridges 15. A flat expanded copper
shield or ground plane 16 is embedded in the lower portion of the
insulation and parallel to the wires 13. The insulation is first
removed from the lower surface of the ground plane along a
transverse strip equal to or slightly wider than the width of the
connector, and the edges are notched adjacent to the outermost
wires as shown at notches 17 in FIG. 1 to provide a close fit
within the connector assembly.
The body 30 is of one piece construction and comprises extended
sides 31, 32, inset ends 33, 34 and bottom 39, defining a recess
40, and a central end projection 35. The outer faces of the ends
are serrated to provide teeth 36, 37 for meshing with cooperating
teeth on the cover. The projection 35 has a wedge-shaped upper end
38 for ease of insertion into a corresponding groove in the
cover.
The cover 50 has a flat upper surface 51, and depending ends 52, 53
having serrated inner faces 54, 55. The two ends 53 are spaced
apart to provide an opening 56 for receiving the projection 35,
thus assuring proper endwise alignment during assembly. The inner
surface of the cover is recessed to provide a shallow recess 57 and
a series of deeper recesses or grooves 58, and the surface forming
the bottom of the recess 57 is provided with parallel transverse
ridges 59 at each side of each groove thereby defining
wire-aligning channels across the inner surface of the cover.
The contact carrier 70 is assembled of two identical halves 71, 72
fitted and held together by cooperating pegs 73 and apertures 74 at
the contacting surface. Each piece is channeled to provide a deep
channel 75 and a shallow channel 76 corresponding to the position
of each of the deep grooves 58 of cover 50. Each piece also carries
a transverse ridge 77 between each two adjacent shallow channels.
The entire surface of each piece is plated with a very thin
conductive metal coating.
The spring compression reserve contact elements 90 have a widened
bifurcate portion 91 and a narrow J-shaped stem portion 92. The
latter fits tightly within the pocket formed by the channels 75;
the base of the bifurcate portion fits within the pocket formed by
the channels 76. The wire-contacting tines 78 extend outwardly
above the surface of the carrier 70.
Contact elements may be inserted in the desired pockets prior to
assembly of the connector, or may be inserted uniformly in all
positions during manufacture, with selective elements then being
withdrawn prior to assembly if desired. The J-shaped stem makes
effective electrical contact with the plated surface of the carrier
70 within the channels 75.
The carrier, with contact elements in the desired locations, is
placed within the frame 30 and the whole is placed beneath the
cable 12 at the uncovered and notched area. The cover is then
pressed over and against the assembly, thereby forcing the contact
elements through the ground plane and insulation and into spring
compression reserve contact with the corresponding wires. The
serrated edges of the cover mesh with those of the body and hold
the entire assembly firmly together, the resiliency of the
components being sufficient to permit the required deflection under
the forces applied in applying the connector.
The contact element 90 makes excellent electrical contact with the
wire-conductor but its contact with the ground plane 16 is
uncertain and is subject to deterioration with subsequent movement
of the cable or connector. However, the plated upper surface of the
contact carrier 70 is held in fully effective contact with the
ground plane and also makes full contact with the stem of the
contact element, so that a fully satisfactory grounding of the
selected wires is achieved.
A typical connector of the invention, for use in conjunction with a
flat cable containing 34 wires of 28 or 30 gauge and an expanded
copper shield in pvc insulation, is two inches in length, one-half
inch wide, and one-fourth inch thick in external dimensions. The
body, cover, and contact carrier are molded of glass filled
polyester injection molding polymer. The two halves of the contact
carrier are plated prior to assembly using a bright tin plate over
a copper flask. The contact elements are of ten mil beryllium
copper, heat treated to spring temper and plated with gold over
nickel.
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