U.S. patent number 3,871,737 [Application Number 05/476,612] was granted by the patent office on 1975-03-18 for socket contact with conductive elastomer contacting surface.
This patent grant is currently assigned to Bunker Ramo Corporation. Invention is credited to Norman Richard Anderson, Robert Francis Dorrell.
United States Patent |
3,871,737 |
Dorrell , et al. |
March 18, 1975 |
SOCKET CONTACT WITH CONDUCTIVE ELASTOMER CONTACTING SURFACE
Abstract
This invention relates to a socket contact which provides a
layer of conductive elastomer material along at least one wall of
the socket hole. A contact in which a complete electrical circuit
is established only when the pin and socket are fully mated may be
provided by utilizing a conductive elastomer material which is
conductive only when placed under compression.
Inventors: |
Dorrell; Robert Francis (Des
Plaines, IL), Anderson; Norman Richard (Cicero, IL) |
Assignee: |
Bunker Ramo Corporation (Oak
Brook, IL)
|
Family
ID: |
26984178 |
Appl.
No.: |
05/476,612 |
Filed: |
June 5, 1974 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
323867 |
Jan 15, 1973 |
|
|
|
|
Current U.S.
Class: |
439/88; 439/86;
439/188 |
Current CPC
Class: |
H01R
13/2414 (20130101); H01R 13/187 (20130101) |
Current International
Class: |
H01R
13/22 (20060101); H01R 13/15 (20060101); H01R
13/24 (20060101); H01R 13/187 (20060101); H01r
013/12 () |
Field of
Search: |
;339/147,255,256,278,DIG.3 ;338/99,100,114 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Attorney, Agent or Firm: Lesser; Norton Arbuckle; Frederick
M.
Parent Case Text
This is a continuation of application Ser. No. 323,867, filed Jan.
15, 1973, abandoned.
Claims
What is claimed is:
1. A socket contact for use in an electrical connector adapted to
receive a metal pin, said pin having a peripheral surface and a
transverse forward end surface for establishing an electrical
connection between said pin and contact comprising:
a metallic contact body having an elongated hole formed therein
with an elongated axis, said hole extending from one end of said
body and defined by an axially extending peripheral surface
portion, a rear metal surface on said body at a position spaced in
one direction from said one end of said body to define a rear axial
end of said hole;
an axially extending layer of conductive elastomer material
positioned in said hole with said layer of elastomer material
having a peripheral surface extending axially of said hole and
engaging said peripheral surface portion of said hole throughout
the axial extent of the peripheral surface of said layer of
elastomer material;
a rear surface on said layer of elastomer material engaged with the
rear metal surface defining the rear axial end of said hole;
and
a forward surface on said layer of conductive elastomer material
spaced from the one end of said body and transverse to the axis of
said pin and hole with the forward surface of said layer of
elastomer material terminating the peripheral surface of said layer
and having an area corresponding to the area of said transverse
forward end surface of said pin and placing said layer of elastomer
material under the axial pressure of said pin between the rear
axial end of said hole and said transverse forward end surface to
establish said electrical connection as a low resistance electrical
path through the transverse forward end surface of said pin and the
forward surface of said layer of elastomer material transverse to
the axis of said pin without deformation of either said pin or
socket contact in response to the insertion of said pin in said
hole to engage said layer of elastomer material under said axial
pressure.
2. A contact as claimed in claim 1 wherein said layer of conductive
elastomer material has an annular portion integrally formed on said
layer of elastomer material engaging the peripheral surface portion
of said hole with said annular portion extending toward the one end
of said body and defining an axially extending recess for receiving
and engaging the peripheral surface of said pin.
Description
This invention relates to socket contacts for electrical connectors
and, more particularly, to a socket contact having a conductive
elastomer contacting surface.
BACKGROUND OF INVENTION
Electrical connectors normally consist of a male element having one
or more projecting pin contacts and a female element having a like
number of socket contacts. These socket contacts have a
pin-receiving hole in their forward face. Some sort of a metallic
spring member is normally either mounted in the hole in engagement
with the walls thereof or is formed from the walls of the contact
member itself. These springs serve to perform the dual function of
physically retaining a pin in the socket and providing good
electrical contact between the pin and socket, the springs also
serve to compensate for any slight misalignment of a pin with its
sockets.
While the springs presently utilized in socket contacts adequately
perform the required functions, they do suffer from certain
shortcomings. First, these springs normally engage the pin at a
point or, at best, over a relatively small area, thus providing a
relatively high contact resistance. The relatively small area of
physical contact also creates high bearing forces thereby
generating excessive wear and galling on thin electro-deposited
precious metals normally applied on contact surfaces. With repeated
use, or as a result of pin misalignment, these springs may also
become bent and distorted resulting in potential spurious open
circuit conditions. Finally, the forming and/or inserting of the
springs is one of the more difficult and expensive operations
involved in making a socket contact. It would, therefore, be
preferable if a simpler, less expensive, more reliable, technique
could be developed for providing physical and electrical contact
with a pin inserted in the socket contact. Such a technique should
be adapted for providing contact over as large an area of the pin
as possible while not creating a critical pin alignment
condition.
Another problem with existing electrical connectors is that
electrical connection is normally effected as soon as the pin comes
into contact with the spring element in the socket even though the
two connector elements have not been fully mated. Where live lines
are being connected, current may start flowing when only a point
contact has been established resulting in arcing and/or potential
burn-out damage to the contacts. In these situations, electrical
contact should not be established until the connector elements are
fully, or at least substantially, mated. While connectors having
this capability do exist, they are generally relatively complicated
and expensive. A simple, inexpensive technique for preventing
electrical circuit from being established through a connector until
its elements have been fully mated is thus required.
SUMMARY OF THE INVENTION
In accordance with the above, this invention provides a socket
contact for an electrical connector which contact has a metallic
contact body with a forward face having an elongated hole formed
therein, the hole extending from the forward face. In place of the
springs of the prior art, this invention provides a layer of
conductive elastomer material which is positioned in the hole along
at least one wall thereof. Where the layer of elastomer material is
positioned only along the rear wall of the hole and the material is
of the type which is conductive only when placed under compression,
a circuit is completed through the socket contact only when the
connected elements are fully mated.
The foregoing and other objects, features and advantages of the
invention will be apparent from the following more particular
description of preferred embodiments of the invention as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut-away side view of a socket contact of a preferred
embodiment of the invention with a mating pin positioned
therein.
FIG. 2 is a cut-away side view of an alternative embodiment of the
invention.
DETAILED DESCRIPTION
Referring now to FIG. 1, it is seen that a socket contact 10 having
a metallic body 11 is provided which contact has a wire crimp
pocket 12 formed in its rear end and a pin-receiving hole 14 in its
forward face. A flange 16 is provided on the contact for use in
retaining the contact in a connector. It should be noted that
pocket 12 and flange 16 do not form part of the present invention.
Thus, any suitable means for permitting the connecting of a wire or
other current carrying element to the contact may be utilized in
place of pocket 12 and flange 16 may be replaced by any other
suitable contact retention element or may be eliminated
completely.
The cross-sectional shape of hole 14 may be circular, square, or
any other desired shape with the peripheral surface 17 of the hole
14 extending from one end 17a of said body 11. The shape of the
hole 14 depending on the cross-section of the metal pin or male
contact 18 with which socket contact 10 is to be mated. Pin 18 has
a peripheral surface 19 and a radial or transverse forward end
surface 19a. The cross-section of hole 14 is slightly larger than
that of the pin and the leading edge of the hole is tapered so as
to permit easy insertion of the pin, and to permit the socket to
accept slightly misaligned pins. Along the rear transverse surface
or wall 20 of hole 14 is a layer 22 of a conductive elastomer
material. Layer 22 may, for example, be an electrically conductive
silicone elastomer or other known conductive elastomer which is
normally conductive. However, for certain applications it is
preferable that layer 22 be of a material such as Pressex,
manufactured by Essex International, which material conducts
electrical current only when compressed. Where Pressex or a similar
conductive elastomer is utilized for the layer 22, an electrical
circuit is not established between socket 10 and pin 18 until the
pin has been fully (or at least substantially) inserted into the
socket, compressing layer 22 to render it conductive under the
axial pressure of said pin against layer 22 and the hole rear metal
surface 19a defining the rear axial end of the hole. Thus,
electrical contact over the entire contacting area is established
before the electrical circuit is completed, preventing possible
arcing or burn-out where live circuits are being connected.
Layer 22 may be rammed into hole 14 and held in by friction, may be
molded to the wall 20, or may be otherwise secured in the hole.
However, regardless of how the elastomer is placed in the hole, the
operation is relatively simple and inexpensive. Further, the
conductive elastomer is not subject to deformation or other
permanent distortion as the result of use, pin misalignment, or
other factors and, covering the entire rear wall of hole 14, the
conductive elastomer makes contact with the pin over a relatively
large area. Thus, the socket of this invention is adapted for
making reliable, relatively low resistance electrical contact with
an inserted pin even after repeated use, and possible misuse, of
the socket.
FIG. 2 shows an alternative embodiment of the invention which
differs from the embodiment shown in FIG. 1 only in that hole 14
has a conductive elastomer layer 24 positioned therein which layer
covers both the rear wall and the side walls of the hole. The space
26 between the side-wall layers of conductive elastomer is
substantially less than the cross-section of pin 18, so that the
elastomer on the side walls is also deformed when a pin is
inserted. This assures good electrical contact between the pin and
the conductive elastomer over substantially the entire length of
the pin which is in hole 14. If a Pressex-type conductive elastomer
is utilized with the embodiment of the invention shown in FIG. 2,
the opening 26 will have to be made quite small so as to assure
adequate pressure on the conductive elastomer along the side walls
to render the elastomer conductive. The portion of the conductive
elastomer layer near the front of the hole 14 is tapered slightly
for ease of pin insertion and to reduce the tolerances on pin
alignment.
An improved socket contact has thus been provided. While the
invention has been particularly shown and described above with
reference to preferred embodiments thereof, it will be understood
by those skilled in the art that the foregoing and other changes in
form and detail may be made therein without departing from the
spirit and scope of the invention.
* * * * *